Ethanol-Quenching Introduced Oxygen Vacancies in Strontium Titanate Surface and the Enhanced Photocatalytic Activity

Modification of the surface properties of SrTiO₃ crystals by regulating the reaction environment in order to improve the photocatalytic activity has been widely studied. However, the development of a facile, effective, and universal method to improve the photocatalytic activity of these crystals remains an enormous challenge. We have developed a simple method to modify the surface environment of SrTiO₃ by ethanol quenching, which results in enhanced UV, visible and infrared light absorption and photocatalytic performance. The SrTiO₃ nanocrystals were preheated to 800 °C and immediately quenched by submersion in ethanol. X-ray diffraction patterns, electron paramagnetic resonance spectra, and X-ray photoelectron spectra indicated that upon rapid ethanol quenching, the interaction between hot SrTiO₃ and ethanol led to the introduction of a high concentration of oxygen vacancies on the surface of the SrTiO₃ lattice. Consequently, to maintain the regional charge balance of SrTiO₃, Sr²⁺ could be substituted for Ti⁴⁺. Moreover, oxygen vacancies induced localized states into the band gap of the modified SrTiO₃ and acted as photoinduced charge traps, thus promoting the photocatalytic activity. The improved photocatalytic performance of the modified SrTiO₃ was demonstrated by using it for the decomposition of rhodamine B and production of H₂ from water under visible or solar light.