Electronic and nanostructure engineering of bifunctional MoS2 towards exceptional visible-light photocatalytic CO2 reduction and pollutant degradation

With recently increasing environmental issues and foreseeable energy crisis, it is desirable to design cheap, efficient, and visible-light responsive nano-photocatalyst for CO2 conversion and pollutant degradation. Herein, we report a flower-like of MoS2-based hybrid photocatalyst with high efficiency through nanostructure and electronic structure engineering. Nanostructure control is used to fabricate MoS2 in to flower-like nanosheets (NSs) with large surface active area. Then MoS2 is coupled with conduction-band edge matched tin dioxide (SnO2) and decorated with Ag nanoparticles for suitable work function to create a unique cascade band alignment electronic structure to facilitate photoexcited charge transfer. It is shown that the amount-optimized nanocomposite of SnO2/Ag/MoS2 exhibits exceptional visible-light photocatalytic activities for conversion of carbon dioxide (CO2) to methane (CH4), approximately one order of magnitude enhancement than original MoS2 with the apparent quantum efficiency 2.38% at 420 nm. Similarly, the optimized sample also shows high activities for 2,4-diclorophenol, Methylene-Blue, Rhodamine-B and Methyl-Orange degradation as compared to pure MoS2. It is clearly demonstrated through combination of hydroxyl radical evaluation, photoelectrochemical and electrochemical impedance, that the enhanced photoactivities are attributed to the increased specific surface area, optimized band alignment for charge transfer and suppressed recombination. Our current work provides feasible routes for further research.