Construction of a ZnIn 2 S 4 /Au/CdS Tandem Heterojunction for Highly Efficient CO 2 Photoreduction.

Photocatalytic CO 2 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 ZnIn 2 S 4 /Au/CdS composite photocatalyst for the CO 2 reduction reaction, where Au nanoparticles (NPs) are evenly anchored on the surface of ZnIn 2 S 4 by photodeposition and Au NPs are wrapped around by CdS. In ZnIn 2 S 4 /Au/CdS composite photocatalysts, Au NPs act as a bridge to construct a "semiconductor-metal-semiconductor" tandem electron transfer mechanism (ZnIn 2 S 4 → 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 2 activity. Under UV-vis light irradiation, the CO yield of ZnIn 2 S 4 /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 ZnIn 2 S 4 , 0.93 μmol·g -1 ·h -1 for CdS, 8.9 μmol·g -1 ·h -1 for ZnIn 2 S 4 /CdS, 31.04 μmol·g -1 ·h -1 for ZnIn 2 S 4 /Au, and 5.37 μmol·g -1 ·h -1 for CdS/Au. In addition, the ternary ZnIn 2 S 4 /Au/CdS composite photocatalyst has good cyclic stability. This study broadens the idea of designing photocatalysts with good carrier separation efficiency.