Photocatalytic reduction of CO2 to CO on CuS/Bi2S3: Construction of Z-type heterojunction to promote the directional transfer of photogenerated electrons

Enhancing the separation efficiency of photogenerated charge carriers and improving electron utilization are the primary challenges limiting the photocatalytic reduction performance. The utilization of heterojunctions to enhance the separation capability of photogenerated charge carriers, thereby increasing the product yield, is a common practice in the photocatalytic reduction of CO2. In this work, a composite material of CuS and Bi2S3 was synthesized via a one-step hydrothermal method, successfully constructing a Z-scheme heterojunction between the two materials. Under the influence of the heterojunction, CuS/Bi2S3 overcame the predicament of rapid recombination of photogenerated charge carriers caused by the narrow bandgap of semiconductor materials. Facilitating the accumulation of electrons at reaction sites on CuS allows for their rapid participation in reactions, leading to increased production of CO2 reduction products. The rate of CO generation from the photocatalytic conversion of CO2 using CuS/Bi2S3 was 108.57 μmol g−1h−1, representing an increase in the carbon monoxide yield by 2.78 times and 2.87 times compared to CuS and Bi2S3 respectively, and CH4 production of CuS/Bi2S3 also increased. This study offers a new understanding of the construction of heterojunctions between metal sulfides.