Accelerated Water Oxidation Kinetics Triggered by Supramolecular Porphyrin Nanosheet for Robust Visible-Light-Driven CO 2 Reduction

Water oxidation is one of the most challenging steps in CO photoreduction, but its influence on CO photoreduction is still poorly understood. Herein, the concept of accelerating the water oxidation kinetics to promote the CO photoreduction is realized by incorporating supramolecular porphyrin nanosheets (NS) into the C N catalyst. As a prototype, porphyrin-C N based van der Waals heterojunctions with efficient charge separation are elaborately designed, in which the porphyrin and C N NS serve as the water oxidation booster and CO reduction center, respectively. Theoretical calculations and relevant experiments demonstrate that the added porphyrin NS reverses the rate-limiting step in the water oxidation while reducing its energy barrier, thus resulting in faster reaction kinetics. Therefore, the optimal sample shows excellent performance in visible-light-driven CO reduction with a maximum CO evolution rate of 16.8 µmol g h , which is 6.8 times that of the C N NS and reaches the current state of the art for C N -based materials in CO photoreduction. Overall, this work throws light that accelerating water oxidation kinetics can effectively improve the CO photoreduction efficiency.