Surface Water Loading on Titanium Dioxide Modulates Photocatalytic Water Splitting

Despite intense efforts during the past decades, most of the existing photocatalysts suffer from low solar energy conversion efficiency. Herein, we examine the photocatalytic mechanism of water splitting on Pt/TiO2 catalysts using in situ solid-state NMR and electron spin resonance (ESR) spectroscopy. The experimental results demonstrate that the formation of H2 and O2− and the subsequent oxidization of surface molecules by O2− all occur on the co-catalyst Pt. It is inevitable that in the absence of sacrifice reagent, the O2− would consume neighboring H2 to regenerate H2O in the traditional method. Accordingly, we propose a new strategy for the photolysis of pure water by controlling water loading on the surface of TiO2, which can hinder H2 to interact with O2− to regenerate H2O. The efficiency of the strategy can reach ∼560 μmol H2/g/h, and the overall solar energy conversion efficiency is determined to be ∼0.46%, while those of the traditional method are negligible.