Tandem ZnCo-porphyrin metal-organic frameworks for enhanced photoreduction of CO2

A bimetallic ZnCo-porphyrin metal-organic framework (ZnCo-BMOF) nanosheet was developed for efficient photoreduction of CO2 to CO. The ZnCo-BMOF nanosheet comprises photosensitizers (Zn porphyrin) and catalysts (Co porphyrin) providing a molecular platform to enable fast electron transfer from photosensitizers (PSs) to atomically dispersed catalytic Co sites. Under visible light illumination, the ZnCo-BMOF nanosheet can efficiently reduce CO2 to CO with a yield of 778 mu mol g(-1) in 6 h, which is 2.8-fold higher than those of its counterparts (Zn-MOF/Co-MOF = physically mixed Zn-MOF and Co-MOF), owing to the improvement of charge transfer capacity and longer lifetime of the photogenerated electron-hole pairs. Density functional theory calculation results reveal that atomically dispersed cobalt sites serve as efficient active sites, which favors accepting electrons from the Zn porphyrin.