Ti3+ self-doped rutile/anatase/TiO2(B) mixed-crystal tri-phase heterojunctions as effective visible-light-driven photocatalysts

Abstract

Ti3+ self-doped rutile/anatase/TiO2(B) mixed-crystal tri-phase heterojunctions photocatalysts are fabricated via hydrothermal approach and mechanochemical process, followed by in-situ solid-state chemical reduction approach. The as-prepared samples are characterized by X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalysts are consisted by anatase/rutile TiO2 nanoparticles and 1D TiO2(B) single-crystalline nanorods, which form rutile/anatase/TiO2(B) tri-phase heterojunctions. The visible-light-driven photocatalytic degradation rates of methyl orange and phenol are up to ∼98 and 97%, which are 2.2 and 1.8 times higher than that of commercial Degussa P25, 2.3 and 2.2 times higher than that of pure TiO2(B) as well. The enhancement can be attributed to the synergistic effect of special nanostructure, tri-phase heterojunctions, oxygen vacancy and Ti3+ self-doping, which facilitates the absorption of visible light and the spatial separation of photo-generated charge carriers. This work provides a new perspective for designing high-active visible-light-driven photocatalyst in future. Keywords: TiO2, Visible-light-driven photocatalysis, Tri-phase heterojunction, Ti3+ self-doped, Pollutants degradation