ALBERT

Description: Ce/ZnO crystallites along with bare ZnO were prepared by solution free mechanochemical method and characterized with powder XRD, SEM, EDX, XPS, UV–Visible and Photoluminescence (PL) spectra. The visible light photocatalytic performance of these materials was investigated for H2 evolution with the aqueous 10vol% methanol solution under one sun conditions using solar simulator. X-ray diffraction data suggests the hexagonal wurtzite structure for Ce/ZnO crystallites and the incorporation of Ce4+ ion in ZnO is supported by the shifting of XRD peaks to lower Bragg angles that indicate lattice expansion. With the increase of Ce content in ZnO, the crystallite size of Ce/ZnO decreases and the specific surface area increases. UV–Visible spectra propose the decrease in optical band gap of Ce incorporated ZnO with the increase of Ce content up to 3 mol. %. The XPS analysis supports the incorporation of Ce4+ in Ce/ZnO. The PL spectra propose that, with the insertion of Ce ions into ZnO, intensity of UV emission band decreases that reflects the low recombination rate of photogenerated charge carriers, which is responsible for higher photocatalytic H2 production. The extent of hydrogen production is affected by calcination temperature of Ce/ZnO. 2 mol. % Ce incorporated ZnO calcined at 600 °C produces43 μmolh−1 g−1 of hydrogen.

Description: Understanding the mechanism of CO2 reduction on iron is crucial for the design of more efficient and cheaper iron electrocatalyst for CO2 conversion. In the present study, we have employed spin-polarized density functional theory calculations within the generalized gradient approximation (DFT-GGA) to elucidate the mechanism of CO2 reduction into carbon monoxide and formic acid on the Fe (100) facet. We also sort to understand the transformations of the other isomers of adsorbed CO2 on iron as earlier mechanistic studies are centred on the transformations of the C2v geometry alone and not the other possible conformations i.e., flip-C2v and Cs modes. Two alternative reduction routes were considered i.e., the direct CO2 dissociation against the hydrogen-assisted CO2 transformation through formate and carboxylate into CO and formic acid. Our results show that CO2 in the C2v mode is the precursor to the formation of both products i.e., CO and formic acid. Both the formation and transformation of CO2 in the Cs and flip-C2v is challenging kinetically and thermodynamically compared to the C2v mode. The formic acid formation is favoured over CO via the reverse water gas shift reaction mechanism on Fe (100). Both formic acid formation and CO formation will proceed via the carboxylate intermediate since formate is a stable intermediate whose transformation into formic acid is challenging both kinetically and thermodynamically. Graphic abstract

Description: The electrochemical production of green and low-cost ammonia requests the development of high-performance electrocatalysts. In this work, the ampoule method was applied to modulate the surface of the zinc electrode by implanting defects and low-valent active sites. The N-doped ZnS electrocatalyst was thus generated by sulfurization with thiourea and applied for electrocatalytic nitrogen reduction reaction (ENRR). Given the rich sulfur vacancies and abundant Zn-N active sites on the surface, excellent catalytic activity and selectivity were obtained, with an NH3 yield rate of 2.42 × 10–10 mol s−1 cm−2 and a Faradaic efficiency of 7.92% at − 0.6 V vs. RHE in 0.1 M KOH solution. Moreover, the as-synthesized zinc electrode exhibits high stability after five recycling tests and a 24 h potentiostatic test. The comparison with Zn foil, non-doping ZnS/Zn and recent metal sulfide electrocatalysts further demonstrated advanced catalytic performance of N@ZnS/Zn for ENRR. By simple synthesis, S vacancies, and N-doping defects, this promising electrocatalyst would represent a good addition to the arena of transition-metal-based catalysts with superior performance in ENRR. Graphic abstract

Description: This study has investigated the effect of the incorporation of graphene foam (GF) into the matrix of a ternary transition-metals hydroxide containing nickel, cobalt, and manganese for optimal electrochemical performances as electrodes for supercapacitors applications. An adopted simple, low-cost co-precipitation synthesis method involved the loading a mass of the ternary metal hydroxides (NiCoMn-TH) onto various GF mass loading so as to find ints effect on the electrochemical properties of the hydroxides. Microstructural and chemical composition of the various composite materials were investigated by employing scanning/transmission electron microscopy (SEM/TEM), x-ray diffraction (XRD), Raman spectroscopy, and N2 physisorption analysis among others. Electrochemical performances of the NiCoMn-TH/200 mg GF composite material evaluated in a three-electrode system using 1 M KOH solution revealed a maximum specific capacity around 178.6 mAh g−1 compared to 76.2 mAh g−1 recorded for the NiCoMn-TH pristine material at a specific current of 1 A g−1. The best mass loading of GF nanomaterial (200 mg GF), was then utilised as a positive electrode material for the design of a novel hybrid device. An assembled hybrid NiCoMn-TH/200 mg GF//CSDAC device utilizing the NiCoMn-TH/200 mg GF and activated carbon derived from the cocoa shell (CSDAC) as a positive and negative electrode, respectively, demonstrated a sustaining specific capacity of 23.4 mAh g−1 at a specific current of 0.5 A g−1. The device also yielded sustaining a specific energy and power of about 22.32 Wh kg−1 and 439.7 W kg−1, respectively. After a cycling test of over 15,000 cycles, the device could prove a coulombic efficiency of ~ 99.9% and a capacity retention of around 80% within a potential range of 0.0–1.6 V at a specific current of 3 A g−1. These results have demonstrated the prodigious electrochemical potentials of the as-synthesized material and its capability to be utilized as an electrode for supercapacitor applications.

Description: There is one component that virtually any embedded wearable needs—a power source. This paper proposes an energy source, which contains no harmful substances, can be stored in a stand-by dry state for indefinite time period, is flexible and has tactile characteristics similar to that of textile. The main feature of this energy source is the separation of the electrolyte and the electrodes—the electrolyte is applied only when the battery needs to be activated. This makes storage time in a dry state virtually infinite. It expands their potential use to storage solutions and healthcare/health monitoring solutions, because the design of the battery allows it to be used as an active sensor, which generates electric current, when it detects liquid. We stress that this solution is suitable for specific applications only, outlined in the paper. The main components of the battery include aluminium anode, air cathode and the cotton shell. The design includes only textile-based materials, which ensure greater flexibility and better fusion with textile materials, where the battery is intended to be integrated. Besides that, results of the experiments with multi-cell battery prototype are presented.

Description: Physical and electrochemical properties of Pd catalysts combined with Ru and Mo on carbon support were investigated. To this end, Pd, Pd1.3Ru1.0, Pd3.2Ru1.3Mo1.0 and Pd1.5Ru0.8Mo1.0 were synthesized on Carbon Vulcan XC72 support by the method of thermal decomposition of polymeric precursors and then physically and electrochemically characterized. The highest reaction yields are obtained for Pd3.2Ru1.3Mo1.0/C and Pd1.5Ru0.8Mo1.0/C and, as demonstrated by thermal analysis, they also show the smallest metal/carbon ratio compared the other catalysts. XRD (X-ray Diffraction) and Raman analyses show the presence of PdO and RuO2 for the Pd/C and the Pd1.3Ru1.0/C catalysts, respectively, a fact not observed for the Pd3.2Ru1.3 Mo1.0 /C and the Pd1.5Ru0.8Mo1.0/C catalysts. The catalytic activities were tested for the ethanol oxidation in alkaline medium. Cyclic voltammetry (CV) shows Pd1.3Ru1.0/C exhibiting the highest peak of current density, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. From, chronoamperometry (CA), it is possible to observe the lowest rate of poisoning for the Pd1.3Ru1.0/C, followed by Pd3.2Ru1.3Mo1.0/C, Pd1.5Ru0.8Mo1.0/C and Pd/C. These results suggested that catalytic activity of the binary and the ternary catalysts are improved in comparison with Pd/C. The presence of RuO2 activated the bifunctional mechanism and improved the catalytic activity in the Pd1.3Ru1.0/C catalyst. The addition of Mo in the catalysts enhanced the catalytic activity by the intrinsic mechanism, suggesting a synergistic effect between metals. In summary, we suggest that it is possible to synthesize ternary PdRuMo catalysts supported on Carbon Vulcan XC72, resulting in materials with lower poisoning rates and lower costs than Pd/C. Graphic abstract

Description: The demand for natural insulation materials is increasing with special attention to the use of such materials for exploiting renewable energy. Natural insulation materials tremendously influence the sustainability development and energy efficiency enhancement in the buildings. Natural fibers from animal’s origin absorb great amount of moisture on exposed to the environment which significantly affects the performance and thermal insulation properties. The thermal degradation of such material strongly influences the accidental burning characteristics, an important selection criteria for building materials. In the present study, three different kind of natural insulation materials namely sheep wool, goat wool and horse mane have been characterized in terms of moisture absorption, thermal degradation and morphology using thermogravimetric analysis (TGA), differential scanning calorimetry techniques, and scanning electron microscopy, respectively. In addition, antibacterial behavioral study has been also carried out for untreated raw wool and treated wool (copper nitrate). These properties are vital for a holistic evaluation of the insulation material. Moisture absorption results indicate that the sheep wool and goat wool absorb less moisture content as compared to horse mane. Unlike this horse mane shows great stability than goat wool and sheep wool in the temperature range not exceeding 470 °C. TGA data indicate 50% mass loss (T50%) at 306 °C, 322 °C and 318 °C for sheep wool, goat wool and horse mane, respectively. In addition the tests show that the content of fire retardant elements like nitrogen and sulphur is more in horse mane as compared to sheep wool and goat wool. The treated wool samples showed excellent antibacterial properties as compared to untreated wool samples.

Description: This study reports the performance analysis of an organic dye-sensitized solar cell (DSSC), introducing MnO2 as an electron transport layer in TiO2/MnO2 bilayer assembly. The DSSCs have been fabricated using TiO2 and TiO2/MnO2 layer-by-layer architecture films onto fluorine-doped tin oxide (FTO) glass and sensitized with natural dye extracted from Malvaviscus penduliflorus flower in ethanol medium. The counter electrode was prepared to layer copper powder containing paste onto FTO's conductive side by the doctor's blade method. The optical, morphological, and structural properties of photoanodes were explored via ultraviolet–visible, field emission scanning electron microscopy, and X-ray diffraction analyses. Moreover, dye complexity and thermostability of dyes were characterized via Fourier-transform infrared spectroscopy and thermogravimetric analyses. The iodide/triiodide (i.e., I−/I3−) redox couple of electrolyte solution was employed as a charge transport medium between the electrodes. Finally, photoanode and counter electrode sandwiches were assembled to envisage the photovoltaic performance potential under simulated AM 1.5G solar illumination using 100 mW cm–2 light intensity. The as-fabricated DSSC comprising TiO2/MnO2 bilayer assembly exhibited 6.02 mA cm–2 short circuit current density (Jsc), 0.38 V open-circuit voltage (Voc), 40.38% fill factor, and 0.92% conversion efficiency, which is about 200% higher compared to the assembly devoid of MnO2 layer.

Description: Two of the important aspects for the successful utilization of phase change materials (PCMs) for thermal energy storage systems are compatibility with container materials and stability. Therefore, the present study is focused on testing the corrosion resistance and surface characteristics of metals in contact with PCMs and thermal behavior of PCMs with heating/cooling cycles. The PCM selection is made by targeting low temperature (

Description: Dye-sensitized solar cells (DSSCs) are under extensive research works due to their appealing features such as low production costs. The production costs and energy conversion efficiency of DSSCs is strongly influenced by the types of dyes used to harvest photons. Natural dyes extracted from different sources are emerged as a potential candidates to synthetic photosensitizers due to their merit properties including low cost, complete biodegradability, availability and less environmental concern. In order to improve the energy conversion efficiency of natural photosensitizers, blending of different dyes, co-pigmentation of dyes, acidifying of dyes and other approaches have been conducted by researchers, resulting in appreciable performance. This paper reviews the factors affecting the stability of anthocyanin pigments and also the solvents needed for efficient extraction of anthocyanins. Moreover, the potential application of anthocyanin dyes as photosensitizers for DSSC along with the work done over the years is covered.