Negative impact of surface Ti3+ defects on the photocatalytic hydrogen evolution activity of SrTiO3.

Defects play an important and in many cases dominant role in the physical and chemical properties of many oxide materials. In this work, we show that the surface Ti³⁺ defects in SrTiO₃ (STO), characterized by electron paramagnetic resonance and X-ray photoelectron spectroscopy, directly impact the photocatalytic activity of STO. O₂ species are found to absorb preferentially on Ti³⁺ defect sites. Hydrogen evolution under ambient air diminishes with the increase in the concentration of surface Ti³⁺ . This is explained by the over-accumulation of Pt cocatalysts on the site of surface Ti³⁺ defects after the removal of adsorbed O₂. [ABSTRACT FROM AUTHOR]