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

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@La₂Ti₂O_7-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.