Z-scheme ZnIn2S4/CuxO heterostructure on flexible substrate for efficient photothermal catalytic CO2 reduction

The ZnIn 2 S 4 nanosheets were successfully synthesized on the surface of compacted stainless steel mesh using a simple solvothermal method, and further modified with Cu x O nanoparticles to form ZnIn 2 S 4 /Cu x O heterojunction photocatalyst via a wet chemistry approach. These photocatalysts were then utilized for photothermal catalytic CO 2 reduction under full spectrum solar light. The experimental results demonstrated that the deposition of the photocatalyst on the flexible substrate effectively prevented the aggregation of ZnIn 2 S 4 nanosheets. The incorporation of Cu x O nanoparticles enhanced the specific surface area of the photocatalyst, and created a Z-scheme heterojunction with ZnIn 2 S 4 to improve the utilization efficiency of photogenerated electrons. It was noteworthy that the dark red Cu x O exhibited a full spectrum response and excellent photothermal effect, thereby facilitating carrier migration and reducing CO 2 catalytic reaction barriers. Consequently, the optimized ZnIn 2 S 4 /Cu x O exhibited significantly enhanced CO 2 to CO yield of 1515.8 μmol m -2 h −1 and CH 4 yield of 1579.4 μmol m -2 h −1 , which was about 7.5 and 7.6 times higher than those achieved by pure ZnIn 2 S 4 , respectively. Furthermore, this study provided detailed insights into the mechanism of photocatalytic CO 2 reduction over composite material as well as valuable guidance for designing immobilized photocatalysts with high activity for CO 2 reduction.