Preparation of Ti3+ self-doped TiO2 nanoparticles and their visible light photocatalytic activity

Abstract

Ti3+ self-doped TiO2 nanoparticles were synthesized by hydrothermal treatment of a gel precursor obtained using TiH2 as the Ti source and H2O2 as oxidant. The effects of different states of gel and hydrothermal treatment time on the properties of the samples were studied. The structure, crystallinity, morphology, and optical properties of the nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microcopy, and UV-visible diffuse reflectance spectroscopy. The chemical states of Ti and O were confirmed by X-ray photoelectron spectroscopy and electron spin resonance spectroscopy. Methylene blue (MB) solutions were used as simulated wastewater to evaluate the visible-light photocatalytic activity of the samples. The samples exhibited strong absorption in the visible light region compared with pure TiO2 and an excellent performance in the photocatalytic degradation of MB. When yellow gel was used as the precursor, the sample obtained after hydrothermal treatment at 160 °C for 24 h exhibited the best visible light photocatalytic activity with a reaction rate constant of 0.0439 min−1, 18.3 times that of pure TiO2. The samples also showed excellent cyclic stability of the photocatalytic activity.