Distribution and concentration of surface oxygen vacancy of TiO2 and its photocatalytic activity

Abstract

Oxygen vacancies in transition-metal oxides can facilitate photocatalysis activity critical for environmental remediation and solar energy conversion. Investigation of photocatalytic activity of TiO2 with different amounts of the oxygen vacancies can provide fundamental insights into the oxygen-vacancy-dependent reaction mechanisms. Here, the oxygen vacancies in TiO2 nanoparticles were investigated by the combination of transmission electron microscopy with electron energy loss spectra, x-ray near-edge structures, and x-ray absorption techniques. The results demonstrate that the oxygen vacancies mainly exist at the surface of TiO2 and the crystalline structure of TiO2 almost keeps no change during annealing under the different oxygen pressures at 500 °C. The exact quantity and distribution of the oxygen vacancies in TiO2 nanoparticles were obtained. The surface oxygen vacancies on TiO2 significantly enhance photocatalytic activity for Rhodamine B degradation and hydrogen generation. The formation of oxygen vacancies at the TiO2 surfaces is responsible for engineering the band gap of TiO2 and tailoring their electronic structures, and promoting light absorption and enhancement photocatalysis. This work could provide new insights into the understanding of the photocatalytic activity enhancement by the surface oxygen vacancies.