Oxygen Vacancies Defective La2Ti2O7 Nanosheets Enhanced Photocatalytic Activity of Hydrogen Evolution under Visible Light Irradiation

Abstract

A novel and efficient technique has been designed for the creation of oxygen vacancies on La2Ti2O7 (LTO) nanosheets. This is achieved via a controlled solid-state reaction between NaBH4 and LTO nanosheets. Transmission electron microscopy (TEM) analyses expose that these processed LTO specimens possess a unique crystalline core/amorphous shell structure, represented as La2Ti2O7@La2Ti2O7-x. According to X-ray photoelectron spectroscopy (XPS) observations, there is a notable correlation between the reaction time, temperature, and the concentration of oxygen vacancies. The concentration of these vacancies tends to increase along with the reaction time and temperature. Concurrently, UV-Visible spectra and photocatalytic tests reveal a significant impact of oxygen vacancies on the LTO surface on both light absorption and photocatalytic functionality. Most notably, the LTO nanosheets with engineered oxygen vacancies have demonstrated an exceptional photocatalytic capacity for hydrogen production under visible light. The maximal activity recorded was an impressive 149 μmol g−1 h−1, which is noticeably superior to the performance of the pristine La2Ti2O7.