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

Modification of the surface properties of SrTiO(3) 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 SrTiO(3) by ethanol quenching, which results in enhanced UV, visible and infrared light absorption and photocatalytic performance. The SrTiO(3) 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 SrTiO(3) and ethanol led to the introduction of a high concentration of oxygen vacancies on the surface of the SrTiO(3) lattice. Consequently, to maintain the regional charge balance of SrTiO(3), Sr(2+) could be substituted for Ti(4+). Moreover, oxygen vacancies induced localized states into the band gap of the modified SrTiO(3) and acted as photoinduced charge traps, thus promoting the photocatalytic activity. The improved photocatalytic performance of the modified SrTiO(3) was demonstrated by using it for the decomposition of rhodamine B and production of H(2) from water under visible or solar light.