Single-Electron-Trapped Oxygen Vacancy on Ultrathin WO3·0.33H2O {100} Facets Suppressing Backward Reaction for Promoted H2 Evolution in Pure Water Splitting.

Solar water splitting to produce hydrogen is a promising solution for global energy issues. One of the main bottlenecks in this technology is the spontaneous fast backward reaction (2H2 + O2 → H2O, Δ G < 0), limiting the solar energy conversion efficiency. How to suppress backward reaction is vitally important but rarely reported. Here we found that single-electron-trapped oxygen vacancy (Vo·) can suppress spontaneous backward reaction in pure water splitting. Taking WO3·0.33H2O catalyst as an example, ultrathin WO3·0.33H2O {100} facets with large amount of surface Vo· realized a continuous H2 evolution from pure water splitting with a productivity of 9.9 μmol/g·h without the assistance of any sacrifice agent and noble metal cocatalyst. Quantum chemical calculations revealed that the backward-reaction suppression ability of Vo· is attributed to the high concentration of localized electrons around Vo·, stimulating unidirectional simultaneous water dissociation into H and OH under light irradiation.