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

Abstract

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 μmol 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.