Ru/In Dual-Single Atoms Modulated Charge Separation for Significantly Accelerated Photocatalytic H-2 Evolution in Pure Water

Photocatalytic hydrogen production is a prospective technology to solve the energy crisis and environmental problems. However, it is still challenging to produce hydrogen from photocatalytic water splitting on a large scale without a sacrificial agent and cocatalyst. Here, it is demonstrated that the dual doping of Ru/In single atoms on TiO2 (Ru-In SA/TiO2) can modulate the separation of photogenerated carriers during the photocatalytic splitting of pure water. Impressively, the H-2 evolution rate of Ru-In SA/TiO2 reaches 174.1 mu mol h(-1), which is 6, 18, and 53 times higher than those of the Ru single-atom decorated TiO2, In single-atom decorated TiO2, and pristine TiO2, respectively. More importantly, Ru-In SA/TiO2 outperforms most of the reported photocatalysts for photocatalytic water splitting in the absence of a sacrificial agent. Detailed investigations reveal that the decoration of Ru/In dual-single atoms leads to the remarkable increase of Ti3+ and enrichment of oxygen vacancies, which accelerate the charge separation. In particular, the femtosecond transient absorption spectroscopy suggests that the doping of Ru single atom promotes the transfer of photogenerated electrons from TiO2 into Ru, while the doping of In single atom enhances the transfer of photogenerated holes from the TiO2 valence band to In single atoms, as a result of an efficient electron-hole separation. This work not only provides an efficient photocatalyst for H-2 production through pure water splitting in the absence of a sacrificial agent, but also promotes fundamental research on catalyst design and modification.