Construction of ZnCdS Quantum-Dot-Modified CeO2 (0D–2D) Heterojunction for Enhancing Photocatalytic CO2 Reduction and Mechanism Insight

It is important to improve the separation ability of photogenerated electrons and the adsorption capacity of carbon dioxide (CO2) for efficient photoreduction of CO2. Here, we synthesized ZnCdS quantum dots (ZCS-QDs) and cerium dioxide nanosheets (CeO2) using the solvothermal method and calcination method. We combined CeO2 and ZCS-QDs to effectively enhance the charge separation efficiency, and the lifetime of photogenerated electrons was increased 4.5 times. The CO evolution rate of the optimized composite (ZCS-QDs/CeO2) was up to 495.8 μmol g−1 h−1, and it had 100% product selectivity. In addition, the stability remained high after five cycles. The CO2 adsorption capacity of the catalyst surface was observed by in situ FTIR. The test results showed that improving CO2 capture ability and promoting photogenic electron separation had positive effects on enhancing photoreduction of CO2. This study provides a reference for constructing a zero-dimensional–two-dimensional (0D–2D) heterojunction and explores potential CO2 reduction reaction mechanisms.