The Z-scheme transfer of photogenerated electron for CO2 photocatalytic reduction over g-ZnO/2H-MoS2 heterostructure

Effective separation of the photo-generated electrons and holes is critical to heighten the photocatalytic efficiency. For achieving this purpose, we design a Z-scheme g-ZnO/2H-MoS2 heterostructure to spatially separate the photogenerated carriers for promoting the reduction of CO2 on surface of the heterostructure through the calculation of density functional theory (DFT). The g-ZnO/2H-MoS2 heterostructure has a narrow band gap, which is beneficial to speed up the transport of carriers. Simultaneously, the designed heterostructure forms a built-in electric field between the layers to cause the band bending, which is very conducive to separate the photogenerated electrons on g-ZnO and the photogenerated holes on 2H-MoS2 and suppress their recombination effectively. Furthermore, the reaction mechanism of photocatalytic reduction of CO2 to CH4 on g-ZnO/2H-MoS2 is studied. The calculation results show that the Z-scheme charge transfer mechanism reduces the barrier of the potential energy control step compared with the pristine g-ZnO and 2H-MOS2. Our calculation lies a theoretical foundation for designing and developing much highly performed photocatalyst in the photocatalytic reduction of CO2.