Effective Charge Separation in a Dual-Single-Atom Photocatalyst for Sacrificial Agent-Free H₂ Evolution

Abstract

The challenge of achieving efficient photocatalytic H2 production from water splitting without sacrificial agents remains a significant hurdle. Herein, we demonstrate that the dual doping of Cu/Co single atoms on Li-reduced blue TiO2 (Cu–Co SA/BTO) can effectively modulate the charge separation of photogenerated carriers during photocatalytic pure water splitting. Remarkably, the H2 evolution rate of Cu–Co SA/BTO achieves a remarkable value of 1238.15 μmol·g–1·h–1, surpassing that of BTO by 11 times. Particularly, femtosecond transient absorption spectroscopy (fs-TA) and differential charge densities reveal that the efficient electron–hole separation originates from the doping of Cu/Co dual-single atoms. The doping of Cu single atoms boosts electron transfer from the TiO2 conduction band to Cu atoms, while the doping of Co single atoms facilitates photogenerated hole migration to Co single atoms from TiO2. This work establishes a promising photocatalyst design strategy for achieving highly efficient H2 evolution through pure water splitting, marking a significant step toward sustainable and green energy production.