Molecular-level insight into photocatalytic CO2 reduction with H2O over Au nanoparticles by interband transitions
Wenchao Shangguan, Qing Liu, Ying Wang, Ning Sun, Yu Liu, Rui Zhao, Yingxuan Li, Chuanyi Wang, Jincai Zhao
Abstract
Abstract Achieving CO 2 reduction with H 2 O on metal photocatalysts and understanding the corresponding mechanisms at the molecular level are challenging. Herein, we report that quantum-sized Au nanoparticles can photocatalytically reduce CO 2 to CO with the help of H 2 O by electron-hole pairs mainly originating from interband transitions. Notably, the Au photocatalyst shows a CO production rate of 4.73 mmol g −1 h −1 (~100% selectivity), ~2.5 times the rate during CO 2 reduction with H 2 under the same experimental conditions, under low-intensity irradiation at 420 nm. Theoretical and experimental studies reveal that the increased activity is induced by surface Au–O species formed from H 2 O decomposition, which synchronously optimizes the rate-determining steps in the CO 2 reduction and H 2 O oxidation reactions, lowers the energy barriers for the *CO desorption and *OOH formation, and facilitates CO and O 2 production. Our findings provide an in-depth mechanistic understanding for designing active metal photocatalysts for efficient CO 2 reduction with H 2 O.