Construction of a ZnIn2S4/Au/CdS Tandem Heterojunction for Highly Efficient CO2 Photoreduction

Photocatalytic CO2 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 ZnIn2S4/Au/CdS composite photocatalyst for the CO2 reduction reaction, where Au nanoparticles (NPs) are evenly anchored on the surface of ZnIn2S4 by photodeposition and Au NPs are wrapped around by CdS. In ZnIn2S4/Au/CdS composite photocatalysts, Au NPs act as a bridge to construct a "semiconductor-metal-semiconductor" tandem electron transfer mechanism (ZnIn2S4 → 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 CO2 activity. Under UV-vis light irradiation, the CO yield of ZnIn2S4/Au/CdS can reach 63.07 μmol·g-1·h-1, which is higher than that of 6.37 μmol·g-1·h-1 for pure ZnIn2S4, 0.93 μmol·g-1·h-1 for CdS, 8.9 μmol·g-1·h-1 for ZnIn2S4/CdS, 31.04 μmol·g-1·h-1 for ZnIn2S4/Au, and 5.37 μmol·g-1·h-1 for CdS/Au. In addition, the ternary ZnIn2S4/Au/CdS composite photocatalyst has good cyclic stability. This study broadens the idea of designing photocatalysts with good carrier separation efficiency.