Thermal decomposition in-situ preparation of gray rutile TiO2-x/Al2O3 composite and its enhanced visible-light-driven photocatalytic properties

Abstract

A gray TiO2-x/Al2O3 hetero-structure photocatalyst with enhanced visible-light-driven photocatalytic properties was firstly in-situ prepared by the thermal decomposition of Al2TiO5 from a facile embedded sintering technique. The photocatalysts were characterized by X-ray diffraction, N2 adsorption-desorption, field emission scanning electron microscopy, UV–vis diffuse reflectance spectra and electron spin resonance (ESR) tests. Compared with reduced TiO2 (TiO2-x), the gray TiO2-x/Al2O3 samples with different molar ratios displayed higher photocatalytic activity in methylene blue (MB) decomposition under visible light irradiation. The first-order rate constant of K = 0.0104min−1 for the gray TiO2-x/Al2O3 sample with 1:1 M ratio is about 2.42 times greater than that of dark blue TiO2-x. The excellent photocatalytic performance of TiO2-x/Al2O3 was attributed to Ti–O–Al heterojunction and appropriate bulk Ti3+ ions. Notably, the degradation rate of TiO2-x/Al2O3 sample with 1:1 M ratio for MB decomposition reached 86.74% within 180 min under visible light illumination and still remained 80.1% after three cycles, which shows a good application potential in water treatment.