Designing and fabricating a CdS QDs/Bi₂MoO₆ monolayer S-scheme heterojunction for highly efficient photocatalytic...

Achieving efficient photocatalytic degradation of atmospheric volatile organic compounds (VOCs) under sun-light is still a significant challenge for environmental protection. The S-scheme heterojunction with its unique charge migration route, high charge separation rate and strong redox ability, has great potential. However, how to regulate interfacial charge transfer of the S-scheme heterojunction is of significant importance. Here, density functional theory (DFT) calculations were first conducted and predicted that an S-scheme heterojunction could be formed in the CdS quantum dots/Bi₂MoO₆ monolayer system. Subsequently, this novel heterojunction is constructed by in-situ hydrothermal synthesis of CdS quantum dots on monolayer Bi₂MoO₆. Under visible-light, this novel S-scheme system gives a high-efficiency photocatalytic degradation rate (6.04 × 10^-2 min^-1) towards C₂H₄, which is 30.3 times higher than that of pure CdS (1.99 × 10^-3 min^-1) and 41.7 times higher than pure Bi₂MoO₆ (1.45 × 10^-3 min^-1). Strong evidence for the S-scheme charge transfer path is provided by in-situ XPS, PL, TRPL and EPR.