Quenching-induced oxygen vacancy engineering boosts photocatalytic activities of CaTiO3

Abstract

Oxygen vacancies (VOs) play a pivotal role in promoting the photocatalytic activities of perovskite oxides. Herein, we proposed a simple and effective strategy of introducing both surface oxygen vacancies and bulk single electron trapped oxygen vacancies (SETOVs) into CaTiO3 by ethanol quenching. The purchased CaTiO3 was preheated at 800 °C and then the hot CaTiO3 was quenched in ethanol instantly. The ethanol-quenched QE-CaTiO3 delivers much improved photocatalytic activities towards both RhB degradation and hydrogen evolution under visible light irradiation by 6.5 and 65.2 times, respectively, in comparison with the pristine CaTiO3. Both the bulk SETOVs and surface VOs enhance light absorption, and the surface VOs serve as photocatalytic active sites. DFT calculations further reveal the narrowed band gap and accumulated charge density near the Fermi level in QE-CaTiO3, which help the visible light absorption, facilitate charge carriers generation and migration, and promote photocatalytic activities. Our findings provide an efficient and easily scalable approach to engineering oxygen vacancy defects in photocatalysts and other catalysts.