Publication Date:
2016-05-25
Description:
The enhanced photocatalytic performance of various MoS 2 -based nanomaterials has recently been observed, but the role of monolayer MoS 2 is still not well elucidated at the electronic level. Herein, focusing on a model system, hybrid MoS 2 /SnO 2 nanocomposite, we first present a theoretical elucidation of the dual role of monolayer MoS 2 as a sensitizer and a co-catalyst by performing density functional theory calculations. It is demonstrated that a type-II, staggered, band alignment of ∼0.49 eV exists between monolayer MoS 2 and SnO 2 with the latter possessing the higher electron affinity, or work function, leading to the robust separation of photoexcited charge carriers between the two constituents. Under irradiation, the electrons are excited from Mo 4 d orbitals to SnO 2 , thus enhancing the reduction activity of latter, indicating that the monolayer MoS 2 is an effective sensitizer. Moreover, the Mo atoms, which are catalytically inert in isolated monolayer MoS 2 , turn into catalytic active sites, making the monolayer MoS 2 to be a highly active co-catalyst in the composite. The dual role of monolayer MoS 2 is expected to arise in other MoS 2 -semiconductor nanocomposites. The calculated absorption spectra can be rationalized by available experimental results. These findings provide theoretical evidence supporting the experimental reports and pave the way for developing highly efficient MoS 2 -based photocatalysts.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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