Surface Water Loading on Titanium Dioxide Modulates Photocatalytic Water Splitting

Summary: 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.