ALBERT

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): Ayoub H. Jaafar, N.T. Kemp〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reports on the first optically tunable graphene oxide memristor device. Modulation of resistive switching memory by light opens the route to new optoelectronic devices that can be switched optically and read electronically. Applications include integrated circuits with memory elements switchable by light and optically reconfigurable and tunable synaptic circuits for neuromorphic computing and brain-inspired, artificial intelligence systems. In this report, planar and vertical structured optical resistive switching memristors based on graphene oxide are reported. The device is switchable by either optical or electronic means, or by a combination of both. In addition the devices exhibit a unique wavelength dependence that produces reversible and irreversible properties depending on whether the irradiation is long or short wavelength light, respectively. For long wavelength light, the reversible photoconductance effect permits short-term dynamic modulation of the resistive switching properties of the light, which has application as short-term memory in neuromorphic computing. In contrast, short wavelength light induces both the reversible photoconductance effect and an irreversible change in the memristance due to reduction of the graphene oxide. This has important application in the fabrication of cloned neural networks with factory defined weights, enabling the fast replication of artificial intelligent chips with pre-trained information.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306943-fx1.jpg" width="485" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): C.M. Ramos-Castillo, M.E. Cifuentes-Quintal, E. Martínez-Guerra, R. de Coss〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Energy gap engineering in graphene nanostructures is one of the most important topics towards development of graphene-based electronics. In this work, based on the density functional theory, the role of the edge magnetism on the size dependence of Kohn-Sham gap and fundamental energy gap for 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msub〉〈mrow〉〈mtext〉C〈/mtext〉〈/mrow〉〈mrow〉〈mn〉6〈/mn〉〈mtext〉nn〈/mtext〉〈/mrow〉〈/msub〉〈msub〉〈mrow〉〈mtext〉H〈/mtext〉〈/mrow〉〈mrow〉〈mn〉6〈/mn〉〈mtext〉n〈/mtext〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mtext〉n〈/mtext〉〈mo linebreak="badbreak"〉=〈/mo〉〈mn〉2〈/mn〉〈mo linebreak="goodbreak" linebreakstyle="after"〉−〈/mo〉〈mn〉16〈/mn〉〈/mrow〉〈/math〉) hexagonal graphene quantum dots (GQDs) with zigzag edges is studied. We found a transition from a nonmagnetic to an antiferromagnetic state at a certain critical diameter (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mo〉∼〈/mo〉〈/mrow〉〈/math〉 3 nm), characterized by the opening of a Kohn-Sham gap as a consequence of the exchange interaction between localized edge states. Furthermore, the fundamental gap is obtained from the difference between the calculated vertical ionization and electron affinity energies. Such approximation includes relaxation in the exchange correlation potential when the electron is added to the system, which might be useful for GQDs transport properties interpretation. We found a scaling rule for the fundamental gap dependence on quantum dot size, providing a practical way to predict this property for large GQDs with zigzag edges, which currently in most demanding approaches, such as GW, is unfeasible.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306876-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): A-Young Kim, Ryanda Enggar Anugrah Ardhi, Guicheng Liu, Ji Young Kim, Hyun-Jin Shin, Dongjin Byun, Joong Kee Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A hierarchical hollow SnO/SnO〈sub〉2〈/sub〉 heterostructure anode surrounded by a dual carbon layer (DCL@SnO/SnO〈sub〉2〈/sub〉), inner (host) and outer carbon layers, was successfully designed 〈em〉via〈/em〉 a simple hydrothermal method with a single Sn precursor to achieving high-performance Li-ion batteries (LIBs) and Li-ion capacitors (LICs). The carbon nanotube (CNT)-based inner carbon host and an ultrathin outer amorphous carbon layer introduced at the SnO/SnO〈sub〉2〈/sub〉 heterostructure had good elasticity and high electrical properties to prevent volume change and ensure fast Li-ion transport during cycling, respectively. Meanwhile, the SnO/SnO〈sub〉2〈/sub〉 heterostructure comprising p-type SnO and n-type SnO〈sub〉2〈/sub〉 facilitated further fast interfacial Li-ion transfer within the p–n SnO/SnO〈sub〉2〈/sub〉 heterojunction anode 〈em〉via〈/em〉 the acceleration effect induced by the built-in electric field (BEF). The resulting half cells LIBs consisting DCL@SnO/SnO〈sub〉2〈/sub〉 anode shows a high reversible specific capacity of 902.1 mAh g〈sup〉−1〈/sup〉 after 500 cycles at a current density of 1400 mA g〈sup〉−1〈/sup〉. The specific capacity of 347.04 mAh g〈sup〉−1〈/sup〉 was still maintained even at a high current density of 10 000 mA g〈sup〉−1〈/sup〉. Moreover, the maximum energy and power density of 125 W kg〈sup〉−1〈/sup〉 and 200 Wh kg〈sup〉−1〈/sup〉, respectively, were achieved from the half cells LIC comprising DCL@SnO/SnO〈sub〉2〈/sub〉 anode (LIC-DCL@SnO/SnO〈sub〉2〈/sub〉).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A hierarchical hollow SnO/SnO〈sub〉2〈/sub〉 heterostructure anode surrounded by a dual carbon layer (DCL@SnO/SnO〈sub〉2〈/sub〉) is prepared by a simple hydrothermal method using a single Sn precursor. The CNT-based inner carbon host layer is equipped by a nanotail CNT to form a tadpole-like structure. The ultrathin elastic amorphous outer carbon layer buffers the cyclic volume change of the SnO/SnO〈sub〉2〈/sub〉 heterostructure, while its natural properties could realize the formation of thin, instead of thick, solid-electrolyte interphase (SEI) layer to enhance e〈sup〉−〈/sup〉/Li〈sup〉+〈/sup〉 reversibility and transport kinetics during charge charge–discharge cycles. The p–n heterojunction created from SnO/SnO〈sub〉2〈/sub〉 heterostructure facilitates the creation of the built-in electric field (BEF) to promote e〈sup〉−〈/sup〉/Li〈sup〉+〈/sup〉 transport rate during charge–discharge cycling and to maintain a reversible high capacity at a high current density.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306888-fx1.jpg" width="288" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): Chen Han, Xiaoguang Duan, Mingjie Zhang, Wenzhao Fu, Xuezhi Duan, Wenjie Ma, Shaomin Liu, Shaobin Wang, Xinggui Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanocarbon-catalyzed advanced oxidation processes for wastewater remediation are green and state-of-the-art methods, nevertheless, the origins of carbocatalysis remain unresolved. In this study, carbon nanotubes (CNTs) are employed as typical metal-free catalysts for catalytic peroxymonosulfate (PMS) activation and phenol oxidation. The surface chemistry and electronic properties of CNTs are deliberately tailored by liquid acid oxidation and subsequent thermal treatment. It is unveiled that the electron-rich carbon surface and carbonyl groups can affect organic adsorption capacity of the carbocatalysts and modulate persulfate activation in different catalytic manners. Furthermore, the relationship between the surface chemistry (oxygen functionality and electron density) and carbocatalysis is established, which is decisive to regulate the radical/nonradical pathways in the catalytic oxidation for water purification. This study provides new insights to carbon-catalyzed persulfate activation with manipulated reaction pathways and redox potentials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306839-fx1.jpg" width="260" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 152〈/p〉 〈p〉Author(s): Hongtao Guan, D.D.L. Chung〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of macroscale planar arrangement (planar coil, unidirectional and crossply arrangements, with a gap between tow segments) of continuous polyacrylonitrile-based carbon fiber (7.0-μm diameter) 12 K tow on the electromagnetic interference shielding effectiveness for normal-incident unpolarized plane wave is reported at frequencies ranging from 200 to 2000 MHz. The planar coil configuration, which favors magnetic interaction, has not been previously reported for shielding with any material. For all arrangements, the total shielding effectiveness (〈em〉SE〈/em〉〈sub〉T〈/sub〉) is dominated by the absorption loss (〈em〉SE〈/em〉〈sub〉A〈/sub〉), whether the fiber is nickel-coated or not. The nickel coating (0.25-μm thick) increases 〈em〉SE〈/em〉〈sub〉T〈/sub〉 from 2‒6 dB to 13–26 dB for the planar coil configuration, but has little effect for the crossply/unidirectional configuration. Both 〈em〉SE〈/em〉〈sub〉T〈/sub〉 and 〈em〉SE〈/em〉〈sub〉A〈/sub〉 are greatly increased by the nickel coating, which also reduces 〈em〉SE〈/em〉〈sub〉A〈/sub〉's frequency dependence and increases the absorption's fractional contribution to shielding, particularly for the planar coil configuration below 1000 MHz (from 53%‒78% to 83%–94%). The advantage of the crossply configuration over the unidirectional configuration is greater without the nickel coating. Increasing the tow size from 12 K to 24 K (with the gap decreased from 3.0 to 2.0 mm) raises 〈em〉SE〈/em〉〈sub〉A〈/sub〉 for planar coil and unidirectional arrangements. The results agree essentially with electromagnetic theory.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930661X-fx1.jpg" width="262" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 152〈/p〉 〈p〉Author(s): Shang-Fa Pan, Jiang-Long Yin, Xue-Lian Zhu, Xiao-Jing Guo, Ping Hu, Xi Yan, Wan-Zhong Lang, Ya-Jun Guo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, a variety of microporous carbon nanospheres (MCNs) were synthesized by the in-situ approach, and used as metal-free catalysts for direct propane dehydrogenation (DPDH). Pristine MCNs showed excellent catalytic performances for DPDH with initial propane conversion of 26% and propylene selectivity of 87%–88%. Phosphorus (P) modifications with different P sources put different effects on the catalytic performances of MCNs in DPDH, i.e., triethyl phosphate exhibited a positive, while (NH〈sub〉4〈/sub〉)〈sub〉2〈/sub〉HPO〈sub〉4〈/sub〉 and H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉 showed a negative effect on the catalytic performances for the in-situ doping carbon catalysts. The amount of surface oxygenic groups and the graphitization extent of carbon materials are two important factors influencing the catalytic performances of MCNs in DPDH. These results indicate that P modification is an effective way to adjust the catalytic performances of MCNs in DPDH. While, except the dopant itself, the interaction between the dopant and other materials during the synthesis process also influences the surface oxygenic groups and the graphitization degree of carbon materials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306827-fx1.jpg" width="260" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 152〈/p〉 〈p〉Author(s): Jing-Yang You, Xing-Yu Ma, Zhen Zhang, Kuan-Rong Hao, Qing-Bo Yan, Xian-Lei Sheng, Gang Su〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A structurally stable carbon allotrope with plentiful topological properties is predicted by means of first-principles calculations. This novel carbon allotrope possesses the simple space group C2/m, and contains simultaneously 〈em〉sp〈/em〉, 〈em〉sp〈/em〉〈sup〉2〈/sup〉 and 〈em〉sp〈/em〉〈sup〉3〈/sup〉 hybridized bonds in one structure, which is thus coined as carboneyane. The calculations on geometrical, vibrational, and electronic properties reveal that carboneyane, with good ductility and a much lower density 1.43 g/cm〈sup〉3〈/sup〉, is a topological metal with a pair of nodal lines traversing the whole Brillouin zone, such that they can only be annihilated in a pair when symmetry is preserved. The symmetry and topological protections of the nodal lines as well as the associated surface states are discussed. By comparing its x-ray diffraction pattern with experimental results, we find that three peaks of carboneyane meet with the detonation soot. On account of the fluffy structure, carboneyane is shown to have potential applications in areas of storage, adsorption and electrode materials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306360-fx1.jpg" width="314" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 152〈/p〉 〈p〉Author(s): Xinfeng Zhou, Zirui Jia, Ailing Feng, Xiaoxiao Wang, Jiajia Liu, Meng Zhang, Haijie Cao, Guanglei Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The novel three-dimensional (3D) co-doped carbon foam was fabricated via a facile hydrothermal and subsequent pyrolysis process using fish skin as carbon precursor. The fish-derived carbon foam (CFs) obtained at 650 °C (CFs-650) possesses large specific surface area of 1369.3 m〈sup〉2〈/sup〉/g with natural inherited micropore-dominate porosity. Moreover, the heteroatoms O and N in the fish skin are uniformly planted into the carbon frameworks, which is highly advantageous for the attenuation of microwave energy. The unique architecture endows the 3D carbon foam with impressive microwave absorbing property. Especially, the broadest bandwidth (RL  〈  −10 dB) of CFs-650 can be up to 8.6 GHz (9.4–18 GHz) at 3 mm with the minimum reflection loss (RL) of −33.5 dB. The optimal RL of CFs-650 is −52.6 dB at 15.8 GHz with the matching thickness of 2.6 mm. The mechanism of the microwave absorption of the carbon foam is attributed to electric conductive loss, interfacial polarization relaxation, multiple reflections and scattering. The low-cost and eco-friendly carbon foam has great potential for application of microwave absorption.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319306566-fx1.jpg" width="291" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon〈/p〉 〈p〉Author(s): Yushun Zhao, Chao Wang, Hong-Hui Wu, Jianyang Wu, Xiaodong He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hierarchical helical structures extensively exist in both natural and artificial systems and hold remarkable mechanical properties. Here, tensile mechanical properties of metahelix designed by twisting multiply twisted helical carbon nanotube ropes are investigated by coarse-grained molecular dynamic simulations. One-level metahelix are slightly mechanically strengthened with increasing twist angle 〈em〉α.〈/em〉 However, two-level ones are more sensitive to the twist operation angles 〈em〉α〈/em〉 and 〈em〉β〈/em〉, with maximum reduction in strength and Young's modulus by 64% and 87%, respectively. Three distinct failure modes are identified, although all metahelix show brittle failure under tension. For type I fracture mode, regardless the twist angle in metahelix, stress is uniformly distributed, resulting in simultaneous breakage of bonds at a cross-section. The type II and III failure modes are featured by stepwise localized failures, resulting from non-uniform stress distribution along each filament and identical cross-section of metahelix. This work provides molecular insights into optimal mechanical performance of CNT-based hierarchical helical yarns.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308954-fx1.jpg" width="87" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Balaram Thakur, Surakanti Srinivas Reddy, U.P. Deshpande, G. Amarendra, Sujay Chakravarty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The origin of magnetism in RF magnetron sputtered deposited carbon thin films is reported. Three different carbon thin films were deposited using RF magnetron sputtering of carbon target by Ar ions at RF power of 50 W, 100 W and 150 W, respectively. Microstructural characterization of films using Raman spectroscopy confirms the presence of graphitic crystallites in all three films and the crystallite edges are terminated with the sp〈sup〉3〈/sup〉 bonding. However, increasing RF power results in an increase in graphitic crystallite size as well as the sp〈sup〉2〈/sup〉/sp〈sup〉3〈/sup〉 hybridization ratio, while the average density of the films decreases. The observed magnetization (measured using SQUID-VSM) in all the three-carbon films has a contribution from both superparamagnetic (SPM) particles (due to the interaction between unpaired spins) and the paramagnetic term due to isolated unpaired spins distributed throughout the film. The origin of experimentally observed magnetization in the carbon thin films and their correlation with the change in density and sp〈sup〉2〈/sup〉/sp〈sup〉3〈/sup〉 hybridization ratio due to variation in RF power is discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308322-fx1.jpg" width="259" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Shizheng Wen, Shiwu Gao, ChiYung Yam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Our previous work demonstrated that graphene devices with monovacancy defects possess spin filtering effect which offers potential applications in spintronics. Here, using first-principles calculations, we further study the spin-dependent electron transport properties and spin filtering efficiency of graphene devices with double vacancies that are arrayed in parallel and serial connections. It is found that devices with vacancies in parallel connection follow classical Kirchhoff circuit law. Both spin-up and spin-down currents are amplified while spin filtering efficiency remains the same as compared to the monovacancy devices. In contrast, amplification of spin filtering efficiency is realized in devices with serially connected double vacancies. In addition, it is shown that the spin current can be flipped reversibly by nanomechanical deformation as we observed in devices with monovacancy. Our findings demonstrate the possibility to engineer the spin filtering effect for vacancy based spintronic devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Amplification of spin-filtering effect in serial and parallel spin circuits designed with two-atomic-vacancies in graphene.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308334-fx1.jpg" width="287" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Wenchao Jiang, Junqing Pan, Jing Wang, Jiaqi Cai, Xu Gang, Xiaoguang Liu, Yanzhi Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A coin-shaped porous carbon is produced by carbonization of Al-based metal-organic frameworks and followed by the removal of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 though dissolving in NaOH solution. The hierarchically porous carbon has a large surface area (1,508 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉) with suitable size of mesopores (6.35 nm). The material exhibits an increased specific capacitance of 323 F g〈sup〉−1〈/sup〉 at 1 mV s〈sup〉−1〈/sup〉. It also has excellent high current discharge performance and superior stability with 97.9% retention at an ultra-high current density of 100 A g〈sup〉−1〈/sup〉 during 15 × 10〈sup〉4〈/sup〉 cycles. The constructed symmetric solid supercapacitor shows an appreciably large capacitance of up to 117.2 F g〈sup〉−1〈/sup〉 at 0.2 A g〈sup〉−1〈/sup〉, corresponding to the high energy density of 36.5 W h kg〈sup〉−1〈/sup〉 within a voltage window of 1.5 V. In addition, it offers satisfied durability with 11.5% decay rate after 20,000 cycles. The carbon with improved electrochemical properties is most likely attributed to its special coin shape and hierarchically porous pores. It is a new potential strategy to configure unique structure porous carbon materials for power supercapacitors via metal-organic frameworks serving as precursors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308395-fx1.jpg" width="460" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Mengmeng Zhang, Wenjun Zhang, Naisheng Jiang, Don N. Futaba, Ming Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The amount and uniformity of carbon nanotubes (CNT) interfacial surface area are one of the key aspects limiting the usage of CNT in composite materials. We report a simple methodology to quantitatively determine the amount and uniformity of CNT interfacial surface area (i.e. level of space filling) using fractal dimension calculation based on scanning electron microscopy images. In this way, we clarified the relationship between the level of space filling of CNT interfacial surface area (fractal dimension) and the properties of rubber and plastic composites to directly relate the dispersion to the composite properties. Our results showed that the electrical conductivity and the tensile strength of composites increased exponentially and linearly with the increased level of space filling of CNT interfacial surface area, respectively within our experimental range. Importantly, these relationships were general, that is, independent of dispersion methods, CNT concentration, CNT types and kinds of matrix (such as rubber, plastic). Taken together, these results serve as a general map to increase the level of space filling of interfacial surface area through controlling various dispersion conditions during CNT dispersion, which is of great significance to the fabrication of CNT composites.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308140-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Jun Young Cheong, Lothar Benker, Jian Zhu, Doo-Young Youn, Haoqing Hou, Seema Agarwal, Il-Doo Kim, Andreas Greiner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the last two decades, nanostructured carbon materials have attracted significant attention, as they exhibit unusual physicochemical properties different from their bulk counterpart. Nevertheless, agglomeration and re-stacking of carbon nanostructures have always limited optimal performance, with larger loading amount. To solve this issue, porous and compressible carbon-based sponges have been researched, but most of the previously suggested carbon foams were either not very porous, synthesized at high temperature heat treatment, and/or not applicable for carbon nanoparticles. In this work, we have successfully fabricated ultra-porous (porosity about 98–99%), polyimide-carbon nanoparticle (PI–C) composites by combining Ketjen black nanoparticles with PI short fibers, by simple freeze-drying and subsequent heat treatments at low temperature (240 °C). Based on the analysis, it has been discovered that the fabricated PI-C sponges not only exhibit highly robust mechanical properties but also retain low thermal conductivity even in comparison with pristine PI sponges. This work provides a milestone in fabricating a number of C-electrospun polymeric sponges by freeze drying and subsequent heat treatments, which are expected to be utilized in various fields of research.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308188-fx1.jpg" width="282" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Zeyu Li, Xiao Liang, Qiuming Gao, Hang Zhang, Hong Xiao, Peng Xu, Tengfei Zhang, Zhengping Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel kind of non-precious metal nanohybrid FeNC-900 is synthesized by hard-template with pyrolysis method using Fe-doped ZIF-8 as the precursor. The FeNC-900 has a superstructure of Fe, N co-doped carbonaceous hollow spheres crosslinked by some self-grown carbon nanotubes. The Fe, N co-doped carbonaceous matrix provides the binary electrocatalytic active sites of Fe–N–C and N-doped carbon as the electrocatalytic active sites. And the microstructure of carbonaceous hollow spheres as well as the crosslinked carbon nanotubes not only lead to the large surface area exposing the electrocatalytic active sites but also benefit the transport of the electrons and electrolyte ions and the stability of the microstructure of the nanocomposite. Thus, FeNC-900 shows the comparable electrocatalyst activities with that of state-of-the-art commercial Pt/C for ORR and RuO〈sub〉2〈/sub〉 for OER respectively in both alkaline and acidic electrolytes due to the synergetic binary electrocatalytic active sites as well as the hierarchical porous texture. More importantly, the low ΔE (= E〈sub〉10 mA cm〈/sub〉〈sup〉−2〈/sup〉 - E〈sub〉-3 mA cm〈/sub〉〈sup〉−2〈/sup〉) of 0.691 and 0.784 V in 0.1 M KOH and 0.1 M HClO〈sub〉4〈/sub〉 electrolytes for FeNC-900, respectively, indicating its fascinating bifunctional electrocatalytic activities for ORR and OER in both alkaline and acidic electrolytes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308401-fx1.jpg" width="461" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Shoichi Matsuda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although numerous studies have been performed with the aim of mitigating the inherent challenges associated with Li metal negative electrodes, the commercialization of Li metal-based rechargeable batteries has not yet been realized because of safety concerns and poor cycling performance. The use of a 3D carbon-based matrix as a substrate material is an effective approach to addressing cycling issues associated deposition/dissolution of Li metal. The present study demonstrates that the electrical conductivity of the carbon nanofibers is an important factor determining the Li metal deposition behavior in such 3D matrices. A 3D matrix composed of highly conductive carbon fibers was found to simply function as a pathway for electron transfer, and the deposition of metallic Li preferentially proceeded at the outer surfaces of the matrix rather than the internal pores. In contrast, in the case of a 3D matrix composed of less conductive carbon fibers, Li metal deposition/dissolution occurred in the interior of the matrix, suppressing the undesired formation of dendritic Li. These results show that the proper control of fiber electrical conductivity is crucial for the practical utilization of carbon-based 3D matrices in Li metal-based rechargeable batteries.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307973-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yixuan Li, Anran Song, Wenting Qiu, Shen Gong, Di Wu, Zhu Xiao, Yanbin Jiang, Zhenghong Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two group of CNT/polydimethylsiloxane flexible films were spin coated by using two kinds of CNTs with different length and same aspect ratio. Results shows that the film conductivity decreases as the film thickness decreases, while the film thickness is less than 40 times of the CNT length. And the downward trend of two groups of films are different. Besides, CNT junctions with structure distortion were well observed experimentally. By introducing CNT structure distortion, film size effect and interface constraint effect into the percolation network model, Monte Carlo simulation results can well fit the experimental data. Simulation results show that the decrease in film conductivity is mainly due to the film size effect. And the interface constraint effect is more obverse for the film prepared by long tubes, which lead to a different downward trend between two groups of films. The influence of some important experimental parameters on the film conductivity are also obtained through calculation. All of these experiment and simulation results could benefit for design of flexible conductive films.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The electrical properties of flexible CNT/polydimethylsiloxane composite films with finite thickness strongly depend on the morphology of CNT networks formed during spin coating process.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308504-egi100L9ZCQCML.jpg" width="317" alt="Image 1009" title="Image 1009"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Hieu Trung Bui, Do Youb Kim, Young Yun Kim, Ngan Hong Le, Dong Wook Kim, Jungdon Suk, Yongku Kang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Free-standing and binder-free cathodes composed of macroporous carbon nanofiber (MCNF) were fabricated by electrospinning for use in a Li–O〈sub〉2〈/sub〉 battery. The use of cross-linked polystyrene colloids as templates enabled the as-prepared samples to have interconnected macropores along the MCNF interior with numerous surface openings. Additionally, Pt nanorods (PtNRs) were grown as catalysts on the MCNF surface (PtNR-MCNF) to enhance the performance of the Li–O〈sub〉2〈/sub〉 battery using the cathode. Owing to the open-pore structure of the cathodes, the Li–O〈sub〉2〈/sub〉 cells using the cathodes achieved a specific capacity of approximately 7000 mAh g〈sub〉c〈/sub〉〈sup〉−1〈/sup〉 and even more at a current density of 200 mA g〈sub〉c〈/sub〉〈sup〉−1〈/sup〉. In particular, the Li–O〈sub〉2〈/sub〉 cell using the PtNR-MCNF cathode exhibited higher electrochemical performance in terms of rate capability, energy efficiency, and cycle stability. This study demonstrates that the growth of PtNRs resulted in the formation of poorly crystalized Li〈sub〉2〈/sub〉O〈sub〉2〈/sub〉, which significantly reduced the overpotentials, both during the discharge and the charge. Additionally, it contributed to the considerably prolonged cycle life of the Li–O〈sub〉2〈/sub〉 cell using the PtNR-MCNF (468 cycles) compared to the cell using the MCNF cathode (272 cycles) with a limiting capacity of 1000 mAh g〈sub〉c〈/sub〉〈sup〉−1〈/sup〉 at a current density of 500 mA g〈sub〉c〈/sub〉〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308231-fx1.jpg" width="495" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Chengyong Zhong, Wenxia Zhang, Guangqian Ding, Junjie He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Searching for three-dimensional (3D) semiconducting carbon allotropes with proper bandgaps and excellent optoelectronic properties is always the chasing goal for the new emerging all-carbon optoelectronics. On the other side, 3D carbon materials have also been recognized as promising anode materials superior to commercialized graphite in Li-ion batteries (LIBs). Here, using first-principles calculations, we propose two novel 3D carbon allotropes through acetylenic linkages modification of two structurally intimately correlated 3D carbon structures — carbon kagome lattice (CKL) and interpenetrated graphene network (IGN). The modified CKL is a truly direct-gap semiconductor and possibly possesses the strongest optical transition coefficient amongst of all semiconducting carbon allotropes. The suitable bandgap and small effective masses also imply it can be a good electron transport material (ETM) for perovskite solar cells. As for the modified IGN, it is a topological nodal line semimetal and shows greatly enhanced specific capacity as anode materials in LIBs comparing to that of IGN. Our work not only find two new 3D carbon phases with fabulous physical and chemical properties for high-performance optoelectronics and Li-ion anode material, we also offer a fresh view to create various carbon structures with versatile properties.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308346-fx1.jpg" width="278" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Chun-Chieh Yen, Yu-Chen Chang, Hung-Chieh Tsai, Wei-Yen Woon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present the study on graphene growth on Cu substrate through low power capacitive coupled radio frequency (RF) plasma enhanced chemical vapor deposition. Fully-covered graphene was grown on Cu substrate through a plasma composed of various argon/methane/hydrogen gas ratio with a 50 W RF power source within a minute under a relatively low substrate temperature at 850 ∘C. The nucleation and growth dynamics is further investigated through processing and analysis of the images acquired through scanning electron microscopy, and interpreted with a modified Johnson-Mehl-Avrami-Kolmogorov model. The roles of hydrogen in limiting the nucleation density and stabilization of the graphene grain edges are discussed in light of the analysis, and a time dependent grain expansion rate in which the graphene grains grow fast at the early stage and saturated at later stage is implemented into the model to achieve good fitting of the coverage evolution.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308462-fx1.jpg" width="479" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Zhen Li, Junjie Wei, Jing Ren, Xiaomin Wu, Liang Wang, Dengyu Pan, Minghong Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon-based flexible fiber-based supercapacitors (FFSCs) are promising power sources for portable and wearable electronics, but their applications are limited by low energy density due to a lower specific capacitance of common carbon materials. We fabricated ternary all-carbon fiber electrodes (N-GQD/GH/CF) with improved electrochemical performance. In this structure, graphene hydrogel (GH) was grown on carbon fibers (CFs) to form a 3D interconnected porous network (GH/CF), and nitrogen-doped graphene quantum dots (N-GQDs) with high pseudocapacitive activity were electrodeposited into the GH/CF network. The ternary N-GQD/GH/CF hybrid electrode delivered a volumetric capacitance of 93.7 F cm〈sup〉−3〈/sup〉 at 20 mA cm〈sup〉−3〈/sup〉, which was around 7 times higher than that of the GH/CF, while the capacitance retention after 5000 cycles reached 87.9%, which was only a little lower than that of the GH/CF electrode (90.2%). It indicates the introduction of N-GQDs drastically improves the capacitance of the FFSCs without sacrificing the cycle stability. All-carbon asymmetric FFSCs were assembled using N-GQD/GH/CF as positive electrode and GH/CF as negative electrode. The assembled FFSCs exhibited a high energy density of 3.6 mW h cm〈sup〉−3〈/sup〉 at power density of 35.6 mW cm〈sup〉−3〈/sup〉 owing to the wider potential window (2 V) and the higher volumetric capacitance as well as excellent flexibility and cycling stability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308449-fx1.jpg" width="343" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): L.X. Zhang, Q. Chang, Z. Sun, J.J. Zhang, J.L. Qi, J.C. Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to the poor wettability of the AgCuTi alloy on the quartz fiber reinforced composite (QFSC), a reliable joining of the QFSC to itself or to other metals can be hardly achieved. In this study, vertically aligned carbon nanotube (VA-CNT) composed of multi-wall carbon nanotube (MWCNT) was synthesized on the QFSC surface by a plasma enhanced chemical vapor deposition method. As a result, the final contact angle decreased from 96.5° (without VA-CNT modification) down to 30.6° (with VA-CNT modification) at 870 °C with 10min holding duration. Besides, the reaction layers at the AgCuTi/QFSC interface transformed into continuous ones and the infiltration effects became more obvious after the VA-CNT modification. Finally, a possible mechanism how VA-CNT enhanced the wettability of the AgCuTi alloy on the QFSC surface was proposed. Defective sites on the MWCNT surface with a high chemical reactivity and the nanoscale capillary structure of the VA-CNT turned out to be the essential factors to promote the wetting process. This novel surface modification approach can offer new insights on addressing the wetting issues in composites preparation, brazing and soldering, etc..〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308474-egi10M98V1FM28.jpg" width="500" alt="Image 1098128" title="Image 1098128"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Ortal Lavi, Ortal Haik, Daniel Hirshberg, Yosef Talyosef, Ella Zinigard, Boris Markovsky, Yulia Vestfrid, Yuval Elias, Doron Aurbach, Daniela Kovacheva〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Round-shaped natural graphite is commonly used as anode material for rechargeable lithium-ion batteries. We report atypical electrochemical behavior of round-shaped graphite anodes in Li-ion batteries: an intriguing phenomenon whereby substantial progressive increase in capacity is observed over tens of cycles. To understand the reasons underlying this abnormal behavior, we investigated the surface and bulk structure properties using HRSEM, XRD and Raman spectroscopy. Graphite particles with tense structure undergo exfoliation and fracture due to multiple transformations in intercalation/deintercalation processes. The increased capacity may result from enhanced particle exfoliation, compared with non-rounded graphite, which is accompanied by appearance of graphene sheets and fracture.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307730-egi10D9D5F56ZN.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Ying Zhou, Kenny Jolley, Rhiannon Phillips, Roger Smith, Houzheng Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The diffusion of point defects after irradiation events in graphite is considered using high temperature molecular dynamics and adaptive kinetic Monte Carlo. The system is modelled with a ReaxFF potential model. It is shown that monovacancies can diffuse both within the graphite layers and also between layers to form stable divacancy and trivacancy structures. Interstitials can also combine, first forming interlayer strings which transform to ring structures. Separated ring structures can also combine to form mobile platelets which can be the seed for new layer formation. When a defective lattice contains a local mixture of vacancies and interstitials, both recombination and larger defect clusters can form. The Dienes defect, cannot easily occur by direct transformation as originally proposed, because of high energy barriers but is shown to occur as an intermediate step in interstitial-defect recombination process. At high temperature the graphite layers bend which has the effect of enhancing defect motion and changing the relative stability of monovacancy structures. The consequences of this are discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307857-fx1.jpg" width="237" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Peng Huang, Wei Qi, Xuan Yin, Junho Choi, Xinchun Chen, Jisen Tian, Jianxun Xu, Huaichao Wu, Jianbin Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrogenated amorphous carbon (a-C:H) is subjected to abnormal high friction in ambient air, and the possibility to retain an ultra-low friction state remains as a great challenge. Here, nanodiamond and graphene were used as solid lubricants to improve the tribological properties of two representative types of a-C:H films with 20 at.% and 40 at.% hydrogen contents, respectively. The results emphasize the exceptionally synergetic lubrication effect of nanodiamond + graphene composite with a mass ratio of 1:1 and a solution-processed concentration of 0.1 mg/mL. An ultra-low friction coefficient of ∼0.02 was achieved for a-C:H (20 at.% H) film, and more strikingly, a dramatic reduction in COF from 0.52 to 0.07 was realized in a-C:H (40 at.% H) film. Meanwhile, the wear rates of the counterparts in both cases are significantly reduced in the presence of nano-lubricants. The lubricity mechanisms are mainly based on the in-situ growth of nanostructured tribolayers. The roles of a-C:H film bonding characteristic and the tribo-induced structural evolution of nano-lubricants in the build-up of anti-friction and wear-resistant tribolayers are discussed. These findings can enrich the understanding of surface modification pathways to a-C:H films via low-dimensional nano-lubricants and help to develop more adaptive and robust solid carbon films.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308073-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Zhihao Zhang, Hannes C. Schniepp, Douglas H. Adamson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The characterization of graphene oxide (GO) is a critical component of any GO based investigation. In this review, we attempt to highlight both the consistencies and inconsistencies of current approaches. Reviewing all of the GO literature would be an impossible task, so recent articles in two research areas are sampled: GO as a dispersant and GO as an emulsion stabilizer. Our goal is to summarize the current state of GO characterization and advocate for the development of more standard approaches to characterization.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307961-fx1.jpg" width="406" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Jialiang Huang, Xuewen Zhao, Hongyang Huang, Zhengdong Wang, Jun Li, Zhihui Li, Xin Ji, Yonghong Cheng, Jinying Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphene is one of the most fantastic nanomaterials and has attracted much attention in various fields. The industrial applications are hindered since there is no effective path to produce scalable few layered graphene without functional groups. Here we report a simple effective green path, a soft ball-microsphere rolling transfer process, to produce bulk quantity of few layered graphene without functionalization. The as-produced graphene nanosheets have been demonstrated by height statistics to have 1–10 layers with average layers of 3.8 ± 1.9 and further confirmed by spectroscopic metrics. No functional groups or contamination have been introduced in the processes. No extra time-consuming purification processes are needed. About 70 mg graphene sheets were obtained from one 500 ml agate tank after process carried out at a speed of 100 rpm for 2 h. The exfoliation can be easily extended to industrial scale by using larger and more agate tanks without the sacrifice of yields.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308243-fx1.jpg" width="282" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Dingbo Chen, Junbo Yang, Jie Huang, Wei Bai, Jingjing Zhang, Zhaojian Zhang, Siyu Xu, Wanlin Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphene-based metasurfaces have emerged as promising photoelectric devices for dynamically controlling the polarization and wavefront of electromagnetic waves. A series of novel graphene-based metasurfaces consisting of split-ring resonators are proposed and researched. A dynamically tunable broadband converter of polarization states composed of periodically patterned graphene split-rings for linearly polarized waves is achieved in terahertz regime. By designing different geometrical parameters, the resonators indicate 2π of smooth phase modulation in a broadband frequency regime. Based on the phase profile design, a polarization beam splitter and a transmission-type focusing metasurface in a broadband frequency regime are both demonstrated successfully. Furthermore, the efficiency of these metasurfaces is dynamically tunable by modulating the gate voltage to change the Fermi energy (〈em〉E〈/em〉〈sub〉〈em〉f〈/em〉〈/sub〉) of graphene. This work may offer a potentially effective method to instruct the design of tunable polarization converter and wavefront-controlling devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308176-fx1.jpg" width="477" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Anne M. Arnold, Brian D. Holt, Caoxin Tang, Stefanie A. Sydlik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The application of functional graphenic materials (FGMs) in medicine has been limited due to insufficient knowledge of long–term degradation and cytocompatibility. Degradation studies that match the timeframe of clinical treatments are difficult to perform due to the limited timeframe in which 〈em〉in vitro〈/em〉 studies can be conducted and the short lifespan of 〈em〉in vivo〈/em〉 animal models. Here, we have designed an 〈em〉ex vivo〈/em〉 experimental approach, where the degradation of FGMs can be monitored indefinitely and sampled at any point during the degradation process. We used this approach to study the aqueous and enzymatic degradation of phosphate graphenes (PGs), which are promising materials for biodegradable bone implants. We found that PGs chemically degrade through cation elution and basal plane scission of polyphosphates, and degradation timeframes are dependent on cation identity. Further, PGs also undergo physical degradation indicated by reduction of particle size. The pathways and timeframes of physical degradation of PGs are different for aqueous and enzymatic conditions. PG degradation was related to structure, which according to kinetic studies of the synthesis, could be manipulated to tune degradation. Nevertheless, all PGs and the resulting degradation byproducts are cytocompatible, opening the door for long–term biomedical applications, such as synthetic bone graft implants.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308024-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yong He, Kaixiong Xiang, Yanfang Wang, Wei Zhou, Yirong Zhu, Li Xiao, Wenhao Chen, Xianhong Chen, Han Chen, Hua Cheng, Zhouguang Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is a great challenge to enhance the specific capacitance while without sacrificing the remarkable rate capability and long-term cycle durability of carbon materials for supercapacitors. Here we present a novel spherical and multi-shell hollow carbon material with tunable shell numbers and N-doping derived from a sequential synthetic route recombining hydrothermal nucleation, carbonization, and etching. The very special features, including uniform in shape and size, hollow structure, core/multi-shell architecture, hierarchical porous structures, and nitrogen doping, facilitated high specific surface area, abundant active sites, fast ion diffusions kinetics and good electrical conductivity. As a result, very superior electrochemical performance with an excellent combination of high specific capacitance (318.5 F g〈sup〉−1〈/sup〉), and outstanding rate capability (the capacity retention ratio was more than 80% when the current density was raised from 0.1 to 10 A g〈sup〉−1〈/sup〉), and very stable cycling (more than 94% capacity retention after 50000 cycles at 1 A g〈sup〉−1〈/sup〉) has been achieved. This hierarchical multi-shell strategy opens a new avenue for design of high performance electrode for next-generation energy storage devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A novel hollow carbon microsphere with controllable shell number and porous architecture has been prepared by a facile sequential synthetic route recombining hydrothermal nucleation, carbonization, and etching and exhibited superior electrochemical performance with an excellent combination of high specific capacitance, outstanding rate capability, and high cycling stability.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308206-fx1.jpg" width="339" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yiyuan Ma, Wenyu Yuan, Yuhang Bai, Heng Wu, Laifei Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poor cycling stability of various pseudocapacitive electrode materials has been a major obstacle facing in front of the development of supercapacitors. Herein, we for the first time bring the toughening mechanism into the design of pseudocapacitive electrode materials to enhance the cycling stability. A hybrid of two-dimensional (2D) NiCo-layered double hydroxides (LDHs) and zero-dimensional (0D) graphene quantum dots (GQDs), in which NiCo-LDHs provide high specific capacitance and GQDs serve as the toughening materials, is designed here. As a result, the GQDs/NiCo-LDH shows high specific capacitance of 2220 F g〈sup〉−1〈/sup〉 under a current density of 1 A g〈sup〉−1〈/sup〉, and the cycling stability is also significantly enhanced. The flexible all-solid-state GQDs/NiCo-LDH//AC supercapacitor delivers a high energy density of 50.84 W h kg〈sup〉−1〈/sup〉, power density of 8 kW kg〈sup〉−1〈/sup〉, and superior flexibility. This work proves that GQDs are promising materials to enhance the performance of pseudocapacitive materials, and provides some new insights for the designing of pseudocapacitive electrode materials.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The toughening design of pseudocapacitive materials via graphene quantum dots was reported for the first time to enhance the cycling stability for supercapacitors.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307882-fx1.jpg" width="336" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Wei Gong, Bunshi Fugetsu, Zhipeng Wang, Takayuki Ueki, Ichiro Sakata, Hironori Ogata, Fei Han, Mingda Li, Lei Su, Xueji Zhang, Mauricio Terrones, Morinobu Endo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work demonstrates a high-energy-density and flexible supercapacitor as a potential energy source for smart electronics devices. Cathode and anode are fiber-shaped electrodes with manganese oxide (MnO〈sub〉2〈/sub〉) being electrochemically inserted into densely interconnected carbon nanotube (CNT) networks as active domains, while carbon fibers (CF) serve as current collectors. The CNT/MnO〈sub〉2〈/sub〉 hybrids are built up as a co-axial shell with an optimized thickness of 1.44 μm surrounding CF. Specific volumetric capacitance is found as high as 527 F cm〈sup〉−3〈/sup〉 when a 1.0 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 aqueous solution is used as electrolyte; when a solid electrolyte (polyvinyl alcohol and lithium chloride, PVA/LiCl) is used, the specific volumetric capacitance is found as high as 492 F cm〈sup〉−3〈/sup〉. These values, to the best of our knowledge, are the highest values of the specific volumetric capacitance among all the MnO〈sub〉2〈/sub〉-based fiber-shaped electrodes reported in previous literature. An all-solid-state (PVA/LiCl) symmetric fiber-shaped supercapacitor cell is assembled and a volumetric energy density of 8.14 mWh cm〈sup〉−3〈/sup〉 which is high enough for driving a portable LED device, is obtained. Our fiber-shaped supercapacitor cell is safe, flexible, and capable of powering smart electronic devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The CNT/MnO〈sub〉2〈/sub〉 hybrid nanostructures are deposited on carbon fibers and the resultant CNT/MnO〈sub〉2〈/sub〉@CF electrodes displaying specific volumetric capacitances of 527 F cm〈sup〉−3〈/sup〉. An assembling symmetric flexible cell with the CNT/MnO〈sub〉2〈/sub〉@CF coaxial electrodes gives a volumetric energy density of 8.14 mWh cm〈sup〉−3〈/sup〉 which is high enough for powering a certain flexible and portable electronic system.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308012-fx1.jpg" width="269" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Chiashain Chuang, Masaaki Mineharu, Masahiro Matsunaga, Chieh-Wen Liu, Bi-Yi Wu, Gil-Ho Kim, Kenji Watanabe, Takashi Taniguchi, Chi-Te Liang, Nobuyuki Aoki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report fabrication and measurements of hexagonal boron nitride (〈em〉h〈/em〉-BN)/chemical vapor deposition (CVD) graphene/〈em〉h〈/em〉-BN heterostructure devices without using expensive, time-consuming electron-beam lithography and toxic carbon tetrafluoride or sulfur tetrafluoride etching. We use efficient transfer of 〈em〉h〈/em〉-BN/CVD graphene by polypropylene carbonate onto a pre-prepared metal contacts/〈em〉h〈/em〉-BN/SiO〈sub〉2〈/sub〉 substrate. In this case, CVD-graphene is suspended from the 〈em〉h〈/em〉-BN substrate which allows efficient gas annealing process for improving the device mobility. Interestingly, we find that the top 〈em〉h〈/em〉-BN capping layer could enhance the carrier interference effect in CVD graphene, a great advantage for low-cost graphene-based interference-type electronic devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉We report fabrication and measurements of hexagonal boron nitride (〈em〉h〈/em〉-BN)/chemical vapor deposition graphene (CVD)/〈em〉h〈/em〉-BN heterostructure devices without using expensive, time-consuming electron-beam lithography and toxic carbon tetrafluoride or sulfur tetrafluoride etching. We use efficient transfer of 〈em〉h〈/em〉-BN/CVD graphene by polypropylene carbonate onto a pre-prepared metal contacts/〈em〉h〈/em〉-BN/SiO〈sub〉2〈/sub〉 substrate. In this case, CVD-graphene is suspended from the 〈em〉h〈/em〉-BN substrate which allows efficient gas annealing process for improving the device mobility. Interestingly, we find that the top 〈em〉h〈/em〉-BN capping layer could enhance the carrier interference effect in CVD graphene, a great advantage for low-cost graphene-based interference-type electronic devices.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930750X-fx1.jpg" width="288" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Piaopiao Wei, Jian Shen, Kangbing Wu, Nianjun Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphene electrochemistry is dependent on the quality of produced graphene. Ultrasonic exfoliation of graphite in a solvent with aid of sodium salts is believed to be a convenient method to prepare high-quality graphene layers, although the effect of sodium salts on the yields of exfoliated graphene and electrochemistry of graphene have not been clearly clarified. Herein, different sodium salts (e.g., sodium citrate, sodium phosphate, and sodium pyrophosphate) with different anions are added during ultrasonic exfoliation of graphite in 〈em〉N〈/em〉-methyl-2-pyrrolidone (NMP). Sodium pyrophosphate improves the most efficiently the graphene yield and decreases the number of graphene layers, leading to the highest defect content. On these defect-rich graphene layers, the redox response of K〈sub〉3〈/sub〉[Fe(CN)〈sub〉6〈/sub〉] exhibits the fastest electron-transfer rate constant. Their active areas are also the largest, as revealed using rotating ring disk electrode and cyclic voltammetry. Moreover, the oxidation signals of biomolecules (e.g., dopamine, uric acid, xanthine, and hypoxanthine), phenolic pollutants (e.g., 4-chlorophenol and 4-nitrophenol), and toxic colorants (e.g., ponceau 4R and rhodamine B) are the mostly enhanced. This work proposes a novel way to synthesize defect-rich exfoliated 2D materials and further to construct universal interfaces for different electrochemical applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Defect-rich graphene was exfoliated ultrasonically with the assistance of sodium salts. Graphene exfoliated with different salt shows differences in yield, thickness, and defect level. The graphene layers exfoliated in the presence of sodium pyrophosphate exhibits the highest electrochemical activity towards redox probes and soluble targets, originating from the highest amount of defect and the reduced layer numbers.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307936-fx1.jpg" width="382" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Hyungjun Heo, Sangjun Lee, Sangin Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We experimentally demonstrated the broadband absorption enhancement of monolayer graphene embedded in the center of a dielectric cavity of the prism coupling configuration in the visible spectral range. The absorption peak is enhanced up to 86.1% at λ = 650 nm with a 3 dB bandwidth of 314 nm (from 542 nm to 856 nm). The absorption performance is the best experimental result for monolayer graphene in the visible range, to the best of knowledge. The improved absorption is attributed to enhanced light-graphene interaction via the cavity mode formed in the dielectric layer with the properly chosen graphene position. The proposed structure is suitable to a high-efficiency broadband photodetector based on monolayer graphene due to the simple fabrication process and the high fabrication tolerance.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307821-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Hanqing Xu, Jianbing Zang, Yungang Yuan, Pengfei Tian, Yanhui Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple route was developed to prepare graphene coating on mild steel balls (MS) by mechanical ball-milling. In order to facilitate the interface reaction, we introduce the Cr layer onto the MS surface (Cr/MS) through vacuum deposition. The graphene coatings were prepared by ball-milling on a buffer Cr/MS double-layered structure. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results indicated the graphene coatings were strongly bonded to the substrate with the help of Cr〈sub〉23〈/sub〉C〈sub〉6〈/sub〉. Raman mapping and STEM results showed that the graphene coating was continuous and homogeneous. The corrosion rate of graphene covered MS was only 0.016 mm year〈sup〉−1〈/sup〉, which was much less than that of MS (1.02 mm year〈sup〉−1〈/sup〉). The graphene coating can significantly improve the wear resistance, the coefficient of friction decreased from 0.225 to 0.18. The present study shed light on a promising strategy for the development of graphene coatings on MS.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307900-fx1.jpg" width="375" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Madhav P. Chavhan, Somenath Ganguly〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heteroatom doping in carbon structure enhances surface wettability, electrical conductivity, and electron-donor/acceptor properties that in turn, improves the electrochemical performance of carbon electrodes. In this article, in situ grown carbon film electrodes are obtained through electrospray of polymeric sol on carbon paper, followed by curing, and carbonization. The nitrogen functionality in these binder-free carbon film electrodes is successfully incorporated from melamine addition in resorcinol-formaldehyde sol. The film electrode shows a capacitance of 223 mF cm〈sup〉−2〈/sup〉 (446 F g〈sup〉−1〈/sup〉), and volumetric energy density of 15.2 mWh cm〈sup〉−3〈/sup〉 at 1 mA cm〈sup〉−2〈/sup〉 in a symmetric cell with 2 M KOH as electrolyte. Furthermore, these electrodes exhibit excellent cyclic stability even after 5000 charge-discharge cycles with almost complete capacitance retention at 5 mA cm〈sup〉−2〈/sup〉. The outstanding electrochemical performance of carbon film electrodes are due to the combined effect of following steps: (i) incorporation of nitrogen and oxygen in right amount, (ii) retention of the desired pore size distribution, and fraction of micropores through systematic balancing of resorcinol to melamine ratio in precursor sol, (iii) disintegration of sol by electrospray prior to deposition on carbon paper, that in turn produces a porous three-dimensional interconnected network of nanoparticulate film, and (iv) lyophilization of wet gel layer that retains the pore spaces during solvent removal.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307845-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): Yunbiao Zhao, Dong Han, Xu Wang, Zhaoyi Hu, Yi Chen, Yuhan Chen, Danqing Zhou, Yue Li, E.G. Fu, Ziqiang Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Direct synthesis of graphene with tunable layer number on semiconductor has proven challenging. Synthesis of layer-tunable graphene on catalytic metal surfaces, in particular Cu and Ni, has shown great success. The growth methods on metal layers involve an inevitable transfer procedure, which degrades and contaminates the graphene. Thus, direct synthesis of graphene on semiconductor is necessary and profound. Here, a facile synthesis approach for direct growth of graphene on Ge(110) subtrate via ion implantation was reported. Interestingly, the graphene growth during annealing is not self-limiting and the thickness of graphene can be precisely controlled by the carbon ion implanted fluence. Moreover, a detailed growth process upon segregation was investigated, and the results show graphene nucleation tends to occur near the Ge atomic step edges. Furthermore, the facile approach involving the ion implantation can be adopted to investigate the growth process on semiconductor and to control the number of graphene layers, thus promoting the practical application of graphene in nanoelectronics.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930716X-fx1.jpg" width="460" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Liangmin Ning, Shengyun Liao, Hui Li, Ruoyan Tong, Caiqiao Dong, Mingtao Zhang, Wen Gu, Xin Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A key challenge faced by the chemical industry is to develop some inexpensive and efficient catalysts with defined sites for selective hydrogenation. Herein, carbon-based materials with specific morphology (Bulks, Nanotubes and Nanosheets, respectively) confined Ni (0) and Ni-N〈sub〉x〈/sub〉 active sites have been synthesized by using one Nickel-organic framework (Ni-MOF) as the precursor in high-temperature treatments under argon atmosphere (designated as Ni (0)/Ni-N-CBK, Ni (0)/Ni–N-CNT and Ni (0)/Ni–N–CNS, respectively). Interestingly, the key to obtaining a specific morphology of the carbon-based materials is altering the amount of additional nitrogen source (dicyandiamide, DCDA). The catalytic performance towards α, β-unsaturated aldehyde hydrogenolysis demonstrates that the Ni (0)/Ni–N-CNT and Ni (0)/Ni–N–CNS possess superior selective hydrogenation activity and stability, which could be put down to the synergy effect of Ni (0) and single atomic Ni-N〈sub〉x〈/sub〉 species.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307924-fx1.jpg" width="388" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Deping Wang, Wenming Hu, Qian Ma, Xuefang Zhang, Xiaohong Xia, Hui Chen, Hongbo Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Graphene has attracted more attention as advanced electrodes for supercapacitors due to its unique geometry structure and outstanding physicochemical property. But its low specific capacitance, especially low volumetric capacitance, has greatly restricted the practical application of graphene electrode materials. Herein, we synthesized nitrogen-containing graphene networks by using 2, 3-diaminopyridine (O-DAP) as functional agent in a facile hydrothermal route. During the hydrothermal process, not only the pyrrolic-N, but also the pyrazine-N is produced in the graphene lattice at the edge/defect site of graphene because of the double –NH〈sub〉2〈/sub〉 in DAP reactant. Owing to the high nitrogen content (17.5 at%), special nitrogen configuration, and high density (1.66 g cm〈sup〉−3〈/sup〉), the N-containing graphene networks present high gravimetric capacitances up to 353 F g〈sup〉−1〈/sup〉 and high volumetric capacitances over 586 F cm〈sup〉−3〈/sup〉 in 1 M H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 electrolyte. More remarkably, the N-containing graphene electrodes exhibit exceptional rate capability with a capacitance retention of 80.6% at a high current density of 20 A g〈sup〉−1〈/sup〉 and good cycling stability of 91.5% retention after 5000 cycles in a symmetrical two-electrode configuration.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930778X-fx1.jpg" width="353" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yang Wang, Jingxiang Xu, Yusuke Ootani, Nobuki Ozawa, Koshi Adachi, Momoji Kubo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Diamond-like carbon (DLC) is one of the most promising solid lubricants for sliding against other materials, such as steel, alumina, and silicon carbide (SiC). During sliding, a DLC transfer film is usually formed on the counterpart surface, affording a low friction coefficient. It is well known that hydrogen in DLC strongly promotes the formation of the DLC transfer film. To further improve the lubricity of DLC, we investigate the formation mechanisms of the DLC transfer film on amorphous SiC and the influence of hydrogen on transfer film formation using reactive molecular dynamics simulations. In addition to the conventional transfer mechanism induced by surface adhesion, we herein propose the new transfer mechanism of “hydrocarbon-emission-induced transfer”. In the proposed transfer mechanism, hydrocarbon molecules are emitted from the DLC surface and subsequently adsorb on the counterpart surface during the continuous grinding of the sliding interface, ultimately generating the DLC transfer film. Furthermore, the addition of hydrogen atoms to DLC slightly increases the adhesion-induced transfer and greatly accelerates the “hydrocarbon-emission-induced transfer”, collaboratively contributing to substantial DLC transfer film formation. Thus, we suggest that the experimentally observed promotion of DLC transfer film formation by hydrogen is largely attributable to our proposed mechanism of “hydrocarbon-emission-induced transfer”.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307833-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Jing Zeng, Jingdong Huang, Jun Liu, Tian Xie, Chaoqun Peng, Yakun Lu, Peijie Lu, Ruizhi Zhang, Jie Min〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two-dimensional (2D) heterostructures composed of the single layer V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 and graphene achieve good chemical diffusion of Li〈sup〉+〈/sup〉, high conductivity and cycling stability. Hence, a simple and novel bottom-up approach has been proposed to build the true single layer V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoribbon/graphene heterostructures. The single layer V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoribbon, which has a thickness of 800 p.m. and are approximate 80 nm in wide, is combined with graphene as sandwich-like heterostructures through the layer-by-layer assembly method. The distinct heterostructures can effectively shorten the practical diffusion pathway for Li〈sup〉+〈/sup〉 and improve the electrical conductivity of the overall electrode. Therefore, the as-prepared ultrathin V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoribbon/graphene heterostructures exhibit excellent reversible capacity and stable cycling performance as a cathode material for lithium storage. Under the current density of 10 C, the electrode made from the ultrathin V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanoribbon/graphene heterostructures has an ultrahigh initial discharge capacity of 225 mAh g〈sup〉−1〈/sup〉 (with corresponding coulombic efficiency of 99.6%) and a superior capacity retention of 92.8% after 600 charge and discharge cycles. In all, rapid ion and electron diffusions, which are the kinetic demands of alternative electrode material for lithium storage, will be satisfied by our single layer heterostructures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930733X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yunyan Xue, Xu Guo, Hongfu Zhou, Jisheng Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrospun hard carbon nanofibers (CNFs) have been considered as promising anode materials for sodium-ion batteries (SIBs). The beads-on-string nanofibers have been frequently appeared as a universal phenomenon during electrospinning, but the influence of beads-on-string on Na-ion storage have never been investigated. Here, in order to clarify this issue, the electrospun polyimide-based CNFs with/without beads-on-string are designed by controlling the concentration of electrospinning solution, and their Na-ion storage properties are investigated as free-standing electrode and slurry-coating electrode, respectively. Generally, the discharge/charge curves of hard carbons consist of slope- and plateau-regions. When used as free-standing electrode, the beads-on-string can depress Na-ion storage behavior of plateau-region, but do not influence storage behavior of slope-region, and, interestingly, the plateau capacity increases with the decreasing of the beads-on-string, while the slope capacity is unaffected by the beads-on-string. When used as slurry-coating electrodes, the beads-on-string can hardly influence Na-ion storage behaviors of slope- and plateau-regions, and CNFs with/without beads-on-string display nearly similar slope and plateau capacities and rate-performance. Moreover, benefiting from the special micro-nanostructure, beads-on-string CNFs exhibit better high rate cycling stability than ones without beads as slurry-coating electrode. Therefore, these interesting phenomena will provide valuable inspiration for designing advanced electrospun CNFs electrode for SIBs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308000-fx1.jpg" width="241" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): E. Louis, E. San-Fabián, G. Chiappe, J.A. Vergés〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zigzag edges of neutral armchair–oriented Graphene Nano–Ribbons show states strongly localized at those edges. They behave as free radicals that can capture electrons during processing, increasing ribbon's stability. Thus, charging and its consequences should be investigated. Total energy calculations of finite ribbons using spin–polarized Density Functional Theory (DFT) show that ribbon's charging is feasible. Energies for Pariser-Parr-Pople (PPP) model Hamiltonian are compatible with DFT allowing the study of larger systems. Results for neutral ribbons indicate: i) the fundamental gap of spin–polarized (non–polarized) solutions is larger (smaller) than experimental data, ii) the ground state is spin–polarized, a characteristic still not observed experimentally. Total energy of GNRs decreases with the number of captured electrons reaching a minimum for a number that mainly depends on zigzag–edges size. The following changes with respect to neutral GNRs are noted: i) the ground state is not spin–polarized, ii) fundamental gap is in-between that of spin–polarized and non–polarized solutions of neutral ribbons, iii) while in neutral ribbons valence and conduction band onsets vs. the fundamental gap, linearly and symmetrically approach mid–gap with slope 0.5, charging induces Fermi level pinning, i.e., the slopes of the valence and conduction bands being about 0.1 and 0.9, in agreement with experiment.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930795X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Hurilechaoketu, Jin Wang, Chaojie Cui, Weizhong Qian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The development of supercapacitors with high energy density calls for multi-functional electrode materials without obvious drawbacks in capacitance performance and in device processing. The highly electroconductive mesoporous activated carbon fibers (MACFs) for 4 V supercapacitors in ionic liquids are proposed. Preparing by the controlled carbonization and activation of polyacrylonitrile-based fibers by CO〈sub〉2〈/sub〉 at high temperature, MACFs exhibit high special surface area (2404 m〈sup〉2〈/sup〉/g), large mesopore volume (2.3 cm〈sup〉3〈/sup〉/g), large packing density (0.25 g/cm〈sup〉3〈/sup〉), high electrical conductivity of 57–195 S/cm, good chemical stability at high voltage and low liquid intake ability. As tested in EMIMBF〈sub〉4〈/sub〉 electrolyte at 4 V, MACFs exhibit high capacitance (204 F/g at 0.5 A/g), high energy density (113 Wh/kg) and excellent capability of capacitance retention. Such excellent capacitance performance is also due to the one-dimensional structure of MACFs, with the long carbon in-plane length for electron transfer in axial direction and the short radial diffusion distance for ions of ionic liquids. To the best of our knowledge, the obtained MACFs are the first material combining all advantages of conventional electrode material (activated carbon) and new generation electrode materials (mainly carbon nanotubes and graphene) together, as well as minimizing their major drawbacks.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307869-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Adrien P. Gillard, Guillaume Couégnat, Sylvain Chupin, Gerard L. Vignoles〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉3D Carbon/Carbon composites have an important use in space propulsion and atmospheric re-entry of space objects. We propose a modeling approach for its non-linear mechanical and thermomechanical behavior based on the introduction of internal interfaces, under the form of cohesive and sliding zones located between the macro-constituents (bundles, matrix pockets). The interface model parameters have been identified from bundle push-out experiments at temperatures from ambient to 1000〈sup〉∘〈/sup〉C. The model allowed reproducing successfully a 45〈sup〉∘〈/sup〉 off-axis tensile test, only with initial damage and interface sliding. The sole incorporation of interface sliding as the only nonlinear phenomenon already allows to successfully reproduce the off-axis behavior. It is also correctly found that the material has a higher yield limit at high temperature, because its interfaces are closing due to thermal expansion of the bundles. The validity of the model does not encompass yet cases where progressive damage of the bundles occurs, as 〈em〉e.g.〈/em〉 in torsion tests.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307948-fx1.jpg" width="489" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 153〈/p〉 〈p〉Author(s): Jincang Su, Wenkang Li, Tengfei Duan, Bin Xiao, Xianyou Wang, Yong Pei, Xiao Cheng Zeng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Antimony has been regarded as a promising anode for Na-ion batteries (NIBs) owing to its high specific capacity and electrical conductivity, as well as low potential range. However, its practical application is largely hindered by the poor cyclability due to the acute pulverization. Herein, we propose a trilayer graphene/antimonene/graphene (G/Sb/G) heterostructure as a potential anode material for NIBs. The aim of this anode design is to markedly increase the surface active sites via modifying the two-dimensional morphology and to alleviate volume expansion by introducing the graphene buffer. Based on density functional theory calculations and 〈em〉ab initio〈/em〉 molecular dynamics simulations, the structural, electronic, mechanical properties, and the Na storage characteristics of the G/Sb/G heterostructure are systematically investigated. The results indicate that the G/Sb/G heterostructure exhibits superior thermodynamic stability, good electronic conductivity and ultrahigh stiffness. The trilayer G/Sb/G heterostructure can provide strong binding with sodium and low-migration barrier for sodium, endowing the anode with high specific capacity and good rate capability. More importantly, the coupling interaction between graphene and antimonene can greatly suppress the structural destruction of the antimonene layer during the sodiation process, offering excellent cyclability. Our findings suggest that the G/Sb/G heterostructure is a promising anode material for practical NIBs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Trilayer graphene/antimonene/graphene heterostructure with excellent structural stability and fast ion transportation can be a promising anode material for the practical application in sodium-ion batteries.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307407-egi10Q3KRS60C5.jpg" width="337" alt="Image 103605" title="Image 103605"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Meilan Pan, Jiong Wang, Ming Hua, Guandao Gao, Xin Wang, Jia Wei Chew〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous graphene represents promising electrocatalysts or substrates of composite electrocatalysts for various electrochemical reactions, and is well-established for renewable energy conversion and environmental remediation. Unfortunately, the lack of comprehensive understanding on the active sites of porous graphene hinders the further development of high-performance electrocatalysts. Herein, porous graphene was established for electrochemical filtration of wastewater, with results indicating that porous graphene exhibited excellent electrochemical activity in terms of high efficiency of oxidation or reduction of organic pollutants. It was experimentally and theoretically demonstrated that the –OH groups generated on the edge of porous graphene served as the active sites for the electrocatalytic reactions. The augmentation of –OH groups at the edges of graphene benefited the inner-sphere electron transfer of the electrocatalytic reactions, improving the electron transfer rates by nearly four times (from 0.034 s〈sup〉−1〈/sup〉 to 0.135 s〈sup〉−1〈/sup〉). Through providing these fundamental insights into the role of the active sites on the pores of porous graphene, this work furnishes future directives for the design of porous graphene-based electrocatalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308371-fx1.jpg" width="228" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Juan Xiong, Zhen Xiang, Jing Zhao, Lunzhou Yu, Erbiao Cui, Bowen Deng, Zhicheng Liu, Rui Liu, Wei Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉NiCo alloy nanoparticles/nanoporous carbon (NiCo/NPC) composites with multilayered structure were synthesized by in situ pyrolysis of the bimetallic NiCo-based metal-organic frameworks. Designable electromagnetic parameters accompanied with a low density, ultrathin thickness, wide absorption bandwidth and strong electromagnetic wave absorption were achieved in the NiCo/NPC composites. An optimum 〈em〉RL〈/em〉 (reflection loss) value of −51 dB at 17.9 GHz with an effective absorbing bandwidth (〈em〉RL〈/em〉  〈  −10 dB) of 4.5 GHz (from 13.5 GHz to 18 GHz) and a thickness of 1.5 mm was obtained for the nanocomposite annealed at 600 °C. The nanoporous carbon with layered structure derived from the NiCo-MOFs contributed to the favorable impedance matching, polarization and multiple attenuations. In addition, the enhanced electromagnetic absorption performance was benefitted from the synergistic effects of the magnetic and dielectric loss among NiCo NPs, graphitized carbon layers and NPC, which was generated from natural and exchange resonance as well as multi-relaxation. This work not only offers a promising way for the development of high-performance electromagnetic wave absorbers, but also provides a valid fabricating concept for the bimetallic NPs/NPC composites.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Layered NiCo alloy nanoparticles/nanoporous carbon composites exhibited an excellence electromagnetic absorption performance due to the synergistic effects of the magnetic and dielectric loss among NiCo NPs, graphitized carbon layer and NPC.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307894-fx1.jpg" width="292" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): So-Yeon Lee, Kyung-Tae Jang, Min-Woo Jeong, Sungtae Kim, Hwanyeol Park, Kuntae Kim, Gun-Do Lee, Miyoung Kim, Young-Chang Joo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An amorphous carbon hardmask was fabricated by DC sputtering to evaluate the etching characteristics for semiconductor microstructure patterning. The bonding structure of the carbon films deposited by sputtering was modified by the DC sputtering conditions and the deposition pressure. In the case of a low-pressure deposition process, an sp〈sup〉3〈/sup〉-bonding-rich amorphous carbon film was fabricated and had excellent etching resistance. On the other hand, during the high-pressure deposition process, an sp〈sup〉2〈/sup〉-bonding-rich amorphous carbon film was fabricated and had poor etching resistance. To understand the degradation process of the carbon hardmask induced by the penetration of fluorine ions into the film during dry etching, the phenomenon of fluorine penetration into the film and the interaction between fluorine and the carbon bonds were studied by density functional theory (DFT). Through the DFT calculations, it is unveiled that the energy barrier for the migration of a fluorine atom through the sp〈sup〉3〈/sup〉 bonding path is much larger than that of a fluorine atom through the sp〈sup〉2〈/sup〉 bonding path in amorphous carbon.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308103-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Zilong Zhao, Fred S. Cannon, Cesar Nieto-Delgado〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sustainable biomaterial binders developed from lignin plus collagen have offered effective binder systems for the fabrication of specialty graphites and graphite electrodes. To further chronicle collagen's synergistic effects and benefits, the authors appraised the formation and evolution of the chars pyrolyzed from lignin, collagen and their blends. Following pyrolysis in a vertical tube furnace at 1000 °C, the lignin-collagen blend yielded more char than did mere lignin or mere collagen. Elemental analysis indicated that along with the release of the oxygenated, nitrogenated, and hydrogen-containing gases, the collagen's presence facilitated carbon-enriched chars with more oxygenated polyaromatic structures. Collagen yielded an aryl (aromatic) carbon source in the aromatic condensation reactions, leading to the continuous cross-linking and growth of the lignin aromatic rings. Per Fourier-transform infrared spectroscopy (FTIR), during pyrolysis, collagen enhanced the hydrogen aromaticity index, and reduced the extent of aromatic substitution. The collagen presence facilitated more removal of functional groups, as indicated by bonded O–H stretching, symmetric CH〈sub〉3〈/sub〉 stretching in O–CH〈sub〉3〈/sub〉, and aliphatic C–H stretching. Scanning electron microscope (SEM) revealed that collagen served as a thermoplastic bio-binder that formed a thermally-fused framework with lignin. Thus, collagen induced significant differences in solidification behaviors and surface morphologies.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319308085-fx1.jpg" width="270" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Huicong Chang, Yi Jia, Lin Xiao, Honghui Chen, Kai Zhao, Yongsheng Chen, Yanfeng Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electro thermal papers have been widely applied in people's daily life. Compared to traditional metal alloy resistance heaters, three dimensional graphene/carbonized-PAN composite freestanding paper with lightweight, good flexibility and excellent electrothermal performance is presented. It retains intrinsic properties of graphene sheets in the bulk state, and exhibits fast electrothermal response under low operation voltage with robust mechanical property. The fastest specific heating rate could be up to 213 °C s〈sup〉−1〈/sup〉 V〈sup〉−1〈/sup〉, and the highest T〈sub〉s〈/sub〉 is 235 °C at low driving voltage just of 1.75 V, which far surpasses those of previous carbon-based film heaters, commercial nichrome wire, and Kanthal wire. These outstanding properties together with the advantage of facile and large-scale fabrication, make the composite paper with great potential applications in flexible electronics.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930805X-fx1.jpg" width="327" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Yun-Hua Cheng, Ji-Hai Liao, Yu-Jun Zhao, Jun Ni, Xiao-Bao Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Combining the extended cluster expansion method and the first-principles calculations, we have systematically investigated the structural stabilities of nitrogen doped C〈sub〉60〈/sub〉 fullerene. With the structural recognition, we have calculated all possible isomers of C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 (n = 1–4) to obtain their ground state structures using the first-principles method. For C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 (n = 5–9) heterofullerenes, we have estimated the energy by the extended cluster expansion method to screen the candidates efficiently, followed by first-principles confirmation for the low-lying structures. For C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 with more than 9 nitrogen atoms, we developed a classification method to select the candidates and successfully obtained the low-lying isomers. The most stable structures for C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 (n = 3–11) we obtained have lower energies compared to the structures in previous studies. Notably, we have found 26 low-lying structures of C〈sub〉48〈/sub〉N〈sub〉12〈/sub〉 azafullerenes, from their 11.6 billion isomers.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉We propose an energy prediction method to deal with the numerous nonequivalent structures, highly improving the structural screening efficiency. Firstly, we obtain the ground states of C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 for n = 2–4 and the interactive energies used for fitting in the ExCE method. Then the ExCE method is used to obtain the low-lying isomers of C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 for n = 5–9. On the basis of the investigations at 2-body substructures in the calculated azafullerenes, we propose a classification method to filter out the majority of the isomers with low stability, therefore we adopt ExCE method to predict the stability of the rested isomers and obtain the most stable isomers of C〈sub〉60-n〈/sub〉N〈sub〉n〈/sub〉 for n = 10–12. Apart from C〈sub〉58〈/sub〉N〈sub〉2〈/sub〉 and C〈sub〉48〈/sub〉N〈sub〉12〈/sub〉, all the most stable isomers we obtained have higher stabilities than those of the ones reported in literatures so far. It is found that azafullerenes will not be stable if there is any pentagonal ring with more than one heteroatom, or two nitrogen atoms are in ortho positions of hexagonal rings. For C〈sub〉48〈/sub〉N〈sub〉12〈/sub〉 heterofullerenes, we have obtained many structures with similar stabilities. Besides the ones predicted by Hultman and Manaa we have found other 24 low-lying isomers whose stabilities are between these two structures.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307791-fx1.jpg" width="261" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Rodrigo A. Bernal, Robert W. Carpick〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We visualize and quantify wear of ultrananocrystalline diamond (UNCD) nanoscale asperities in sliding contact using 〈em〉in-situ〈/em〉 transmission electron microscope (TEM) sliding experiments. By comparing high-resolution TEM images obtained before and after a series of sliding intervals and measuring the normal force, we quantify the evolution of the specific wear rate and visualize the morphological and crystal-structure changes as wear progresses. When two sharp UNCD asperities are slid against each other, the wear rate is initially as high as ∼0.4 mm〈sup〉3〈/sup〉/N·m, but decreases substantially after a few micrometers of sliding to 10〈sup〉−3〈/sup〉 – 10〈sup〉−2〈/sup〉 mm〈sup〉3〈/sup〉/N·m. This latter wear rate is much larger than that observed in macroscale, multiasperity low-humidity experiments (∼10〈sup〉−5〈/sup〉 mm〈sup〉3〈/sup〉/N·m). When a sharp UNCD asperity is slid against a UNCD flat, the wear rate is similarly high at the beginning, but decreases to slightly lower values, sometimes approaching ∼10〈sup〉−4〈/sup〉 mm〈sup〉3〈/sup〉/N·m. In both cases, generation of amorphous debris is evident, providing 〈em〉in-situ〈/em〉 confirmation of previous observations in both atomistic simulations and macroscale experiments. Gradual wear of grains and embedded crystallites in the amorphous debris are also observed. Our experiments suggest amorphization, gradual atomic-scale wear, and fracture all play a role in the nanoscale wear process of self-mated UNCD nanocontacts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307754-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Xu Zhang, Xiaoqun Wang, Fanbo Meng, Jiajun Chen, Shanyi Du〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High-efficiency microwave absorption epoxy nanocomposites filled with ultralow content of non-covalently modified reduced graphene oxides (rGO) are prepared via an in-situ polymerization method. Here, the porous and folded rGO nanosheets are successfully functionalized by strong π-π interaction between conjugated imidazole and graphene sheets. The combination of electron microscope and synchronous radiation X-ray small angle scattering (SAXS) techniques unambiguously illustrates that the non-covalently modified graphene nanosheets in the epoxy composites are well-dispersed and extensively winkle. Hence, compared with pristine rGO/epoxy composites, the composites containing the highly dispersed rGO demonstrate more ideal impedance matching and stronger microwave dissipation based on the experimental and simulated results. The composites remarkably achieve excellent microwave absorptions (minimum reflection loss of −65 dB, with a matching thickness of 1.8 mm), an extremely broad absorbing bandwidth of 7.48 GHz (RL 〈 −10 dB) and ultralow filler loading (1–2 wt%). Moreover, the composites possess high hydrophobicity, endowing them attractive functions of self-cleaning. This work provides a promising, facile and scalable approach for designing and fabricating graphene-based nanocomposites with hydrophobicity and excellent microwave absorption capacities.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307699-fx1.jpg" width="311" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Lei Chen, Zhe Chen, Xiaoyu Tang, Wenmeng Yan, Zhongrong Zhou, Linmao Qian, Seong H. Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although graphene is well known for super-lubricity of its basal plane, friction at its step edge is not well understood. In this study, friction of a single-layer graphene step edge was studied using atomic force microscopy (AFM) in vacuum and humid air conditions. At a 0.34 nm thick graphene step edge, friction varies drastically depending on whether it is exposed at the topmost surface or covered under other graphene layers. The friction response of the step edge buried under one layer of graphene can be fully explained with the topographic effect only; in contrast, the exposed step edge exhibits both topographic and chemical contributions to friction. Chemical characterizations suggest that the exposed graphene step edge is terminated with C–OH groups, which can interact with the AFM tip surface through hydrogen bonding interactions and thus increase friction. The chemical interactions at the exposed step edge significantly amplify the topographic effect. When the step edge is covered by more than one layer of graphene, friction is not sensitive to the 0.34 nm height change. This must be due to the stiffness of multilayer graphene and the height changes gradually at the step edge. These findings will advance fundamental knowledge of the frictional behaviors of graphene.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307742-fx1.jpg" width="430" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Xu Han, Futian Xu, Shuyong Duan, Haifei Zhan, Yuantong Gu, Guirong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon nanofibers (NFs) have been envisioned with broad promising applications, such as nanoscale actuators and energy storage medium. This work reports for the first-time super-elastic tensile characteristics of NFs constructed from a screw dislocation of carbon nanocones (NF–S). The NF–S exhibits three distinct elastic deformation stages under tensile, including an initial homogeneous deformation, delamination, and further stretch of covalent bonds. The delamination process endows the NF–S extraordinary tensile deformation capability, which is not accessible from its counterpart with a normal cup-stacked geometry. The failure of NF–S is governed by the inner edges of the nanocone due to the strain concentration, leading to a common failure force for NF–S with varying geometrical parameters. Strikingly, the delamination process is dominated by the inner radius and the apex angle of the nanocone. For a fixed apex angle, the yielding strain increases remarkably when the inner radius increases, which can exceed 1000%. It is also found that the screw dislocation allows the nanocones flattening and sliding during compression. This study provides a comprehensive understanding on the mechanical properties of NFs as constructed from carbon nanocones, which opens new avenues for novel applications, such as nanoscale actuators.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A screw dislocation endows the cup-stacked carbon nanofiber a super-elastic tensile characteristic, which provides intriguing properties that are beyond the reach of conventional carbon nanofibers.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307778-fx1.jpg" width="498" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Ning Wei, Shanchen Li, Yingyan Zhang, Jige Chen, Yang Chen, Junhua Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal rectification is of great importance in various thermal management and thermal logic applications, where heat flux runs preferentially in one direction over the opposite one. This phenomenon is mostly reported in previous simulations and experiments by introducing asymmetry shape-tailoring, defects and doping, etc. However, these approaches break the structure of the heat conductor. In this paper, we report thermal rectification induced by modulating the substrate stiffness on the supported graphene, which preserves structural integrity of graphene, making it reusable. Our results show that the heat flux prefers to flow toward the stiffer part of a substrate. The maximum thermal rectification factor can reach ∼48% by using the ideal substrate model prediction. Moreover, a wide range thermal rectification factor of 3.5%–22.7% can be achieved by using a sandwich model. These phenomena are explained by phonon vibration spectra and excitation simulations. Our results should be of great help for understanding the modulation of thermal rectification in supported material and shed light on the design of a new thermal logic gate and thermal management devices.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S000862231930781X-egi10CLPV3WD7S.jpg" width="247" alt="Image 1037" title="Image 1037"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Carbon, Volume 154〈/p〉 〈p〉Author(s): Dongdong Cheng, Yelin Zhao, Tong An, Xin Wang, Han Zhou, Tongxiang Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To enable the theoretically appealing Li–S electrochemistry in battery, the issues of the low conductivity and volume variation of the active materials as well as the intermediates diffusion need to be comprehensively addressed, which calls for rational structure design of multifunctional host material for sulfur. Herein, a novel strategy is proposed to construct 3D graphene-based N-doped porous carbon for Li–S batteries. In this strategy, interconnected macropore channels, abundant mesopores and highly accessible micropores are synergistically integrated into a conductive framework constructed by crumpled carbon sheets, and a high content of N-doping (∼18 at%) is simultaneously achieved. The obtained porous carbon possesses 3D conductive network, interconnected hierarchical porosities as well as large polarized specific surface, which endow the carbon matrix multifaceted structural merits for electrons/ions transfer, sulfur accommodation, and polysulfides immobilization. The obtained carbon sulfur composite exhibits a high reversible capacity of 1280 mA h g〈sup〉−1〈/sup〉 at 0.2C, remarkable rate capabilities up to 3C and a prolonged cycling life over 500 cycles at 1C, showing intriguing promise for constructing high energy density Li–S batteries. This strategy provides a new perspective to porosity engineering and surface chemistry modification of carbon-based sulfur hosts and also other electrochemical electrode material.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0008622319307870-fx1.jpg" width="249" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉