Construction of a ZnInS/Au/CdS Tandem Heterojunction for Highly Efficient CO Photoreduction.

Photocatalytic CO reduction technology is of great importance to alleviate energy crisis and environmental pollution; however, it remains a serious challenge due to the fast recombination of carriers. In this study, we report a three-dimensional structure of a ZnInS/Au/CdS composite photocatalyst for the CO reduction reaction, where Au nanoparticles (NPs) are evenly anchored on the surface of ZnInS by photodeposition and Au NPs are wrapped around by CdS. In ZnInS/Au/CdS composite photocatalysts, Au NPs act as a bridge to construct a "semiconductor-metal-semiconductor" tandem electron transfer mechanism (ZnInS → Au → CdS) heterojunction, which greatly promotes the transfer of photogenerated electrons. It is worth noting that Au NPs, as a local surface plasmon resonance (LSPR) effect excited source to generate excited-state electrons, further improve the photoreduction CO activity. Under UV-vis light irradiation, the CO yield of ZnInS/Au/CdS can reach 63.07 μmol·g·h, which is higher than that of 6.37 μmol·g·h for pure ZnInS, 0.93 μmol·g·h for CdS, 8.9 μmol·g·h for ZnInS/CdS, 31.04 μmol·g·h for ZnInS/Au, and 5.37 μmol·g·h for CdS/Au. In addition, the ternary ZnInS/Au/CdS composite photocatalyst has good cyclic stability. This study broadens the idea of designing photocatalysts with good carrier separation efficiency.