Engineering Cu-Co Active Sites in CdIn2S4 for Selective CO2 Photoreduction to CH4

Single-metal doping in photocatalysts can lead to a trade-off between activity and product selectivity. Here, Cu-Co codoping was introduced into CdIn2S4 to regulate the electronic structure and surface reaction properties. The Cu-Co codoping modulates sulfur vacancy concentration, introduces impurity states, and generates surface active sites. These structural modifications broaden visible-light absorption and facilitate charge separation and transfer. The Cu-Co active sites enhance CO2 adsorption and promote the formation of bridging M-C-O-M intermediates, thereby directing CO2 reduction toward CH4 formation. With a selectivity of 99.55%, the optimized catalyst produces CH4 at a rate of 116.58 μmol·g-1·h-1 under visible-light irradiation.