Indium and cerium co-doped mesoporous TiO2 nanocomposites with enhanced visible light photocatalytic activity

Abstract Indium and cerium co-doped mesoporous TiO 2 nanocomposites with different weight percentage were synthesized by sol–gel route using Pluronic P123 as the structure directing template. The synthesized materials were characterized by X-ray powder diffraction, high resolution transmission electron microscopy, scanning electron microscope with energy dispersive X-ray spectroscopy, N 2 adsorption–desorption studies, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy and electron paramagnetic resonance spectroscopy. Indium and cerium co-doped on TiO 2 nanocomposites shifted the light absorption band-edge position to visible region and showed high surface area with large pore diameter. The optimum loading of In 2 O 3 and CeO 2 on TiO 2 was 0.2 wt%. Ce 4+ is good electron scavengers, which easily trapped the exited electrons and transferred the electrons to the adsorbed O 2 molecules to produce O 2 −• . Hence the electron–hole recombination was efficiently suppressed, which was revealed by the photoluminescence spectroscopy. The large number of structural defects by the substitution of In 3+ for Ti 4+ enhanced the surface Bronsted acidity and the adsorption of cationic methylene blue. Consequently, In 2 O 3 /CeO 2 -TiO 2 exhibited promising photocatalytic activity in the degradation of methylene blue under visible light irradiation due to the formation of large number of O 2 −• and • OH radicals.