Study of the effect of oxygen vacancy content on the photocatalytic activity of TIO2 nanoparticles

"TiO2 is one of the most popular metal oxide semiconductors utilized for advanced oxidation processes (AOPs), including in photocatalysis. As the photocatalytic behavior of a metal oxide is known to be controlled by oxygen vacancies (VO), we prepared TiO2 nanoparticles (NPs) of different VO contents through thermally stimulated NaBH4 reduction of commercial TiO2 NPs Degussa P25, to study the effect of the degree of reduction (i.e., the concentration of VO) on their photocatalytic performance, qualitatively. The reduced TiO2 NPs were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS) to understand the effect of NaBH4 reduction on their structural and optical properties. N2 adsorption-desorption isotherms of the samples were studied to analyze their texture parameters. Z-potential analysis was applied to estimate the surface potential of the nanostructures. The reduced and unreduced TiO2 NPs were tested for photocatalytic degradation of methylene blue (MB), a model cationic organic dye. The results obtained in this study indicate that by increasing the amount of NaBH4 in the reaction mixture, we can increase the VO concentration in the nanostructures"