A Cobalt Porphyrin Covalently Bonded by an Amide Linker to ZnIn ₂ S ₄ Nanosheets as a Solar-Driven Photocatalyst for the CO ₂ -to-CO Conversion

Developing efficient and stable photocatalysts for CO2 reduction under visible light remains a significant challenge in solar energy conversion. In this study, we report a rational design of an amide-bonded ZnIn2S4/CoTCPP nanocomposite by covalently coupling amino-functionalized ZnIn2S4 (ZIS) with a cobalt porphyrin (CoTCPP) molecular catalyst. The formation of an amide linkage at the semiconductor–molecular interface promotes effective charge transfer and suppresses charge recombination, thus significantly enhancing photocatalytic CO2 reduction. The optimized ZIS/CoTCPP-4 composite achieved a remarkable CO production rate of 2956.7 μmol·g–1·h–1 under solar-light irradiation, which was 32 times higher than that of pristine ZIS, representing one of the highest CO2-to-CO photoreduction performances reported for ZnIn2S4-based photocatalysts. Furthermore, the establishment of a type-II heterojunction between ZIS and CoTCPP helps facilitate spatial charge separation and directional charge transfer, thereby enhancing photocatalytic efficiency. This work highlights the critical role of interfacial engineering via an amide linkage in enhancing light absorption and charge migration, providing an inspiration for constructing high-efficiency chemical bonded photocatalysts for solar-driven CO2 conversion.