A facile synthesis of brown anatase TiO2 rich in oxygen vacancies and its visible light photocatalytic property

In this report, we present a facile approach for the synthesis of a brown TiO2 material rich in oxygen vacancies under atmospheric conditions with titanium tetrachloride, oxalic acid and anhydrous ethanol as raw materials. The samples were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance (UV–vis DRS), Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), High resolution transmission electron microscope (HRTEM), Fourier transform infrared (FTIR) and Raman. The visible light photocatalytic activity of the samples was evaluated by degrading of methylene blue solution. XRD and Raman results showed that the brown TiO2 was anatase TiO2. XPS and EPR indicated the presence of abundant oxygen vacancies in the brown TiO2. UV–vis DRS illustrated that the brown TiO2 had a strong absorption in the visible light region. The photocatalytic activity measurement indicated that the visible light photocatalytic performance of the brown TiO2 was excellent. The surface oxygen vacancies played a key role for the significant enhancement of the brown TiO2 photocatalytic performance.