Accelerated Water Oxidation Kinetics Triggered by Supramolecular Porphyrin Nanosheet for Robust Visible-Light-Driven...

Water oxidation is one of the most challenging steps in CO₂ photoreduction, but its influence on CO₂ photoreduction is still poorly understood. Herein, the concept of accelerating the water oxidation kinetics to promote the CO₂ photoreduction is realized by incorporating supramolecular porphyrin nanosheets (NS) into the C₃ N₄ catalyst. As a prototype, porphyrin-C₃ N₄ based van der Waals heterojunctions with efficient charge separation are elaborately designed, in which the porphyrin and C₃ N₄ NS serve as the water oxidation booster and CO₂ 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 CO₂ reduction with a maximum CO evolution rate of 16.8 µmol g^-1 h^-1 , which is 6.8 times that of the C₃ N₄ NS and reaches the current state of the art for C₃ N₄ -based materials in CO₂ photoreduction. Overall, this work throws light that accelerating water oxidation kinetics can effectively improve the CO₂ photoreduction efficiency.