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

Indium and cerium co-doped mesoporous TiO2 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 TiO2 nanocomposites shifted the light absorption band-edge position to visible region and showed high surface area with large pore diameter. The optimum loading of In2O3 and CeO2 on TiO2 was 0.2 wt%. Ce4+ is good electron scavengers, which easily trapped the exited electrons and transferred the electrons to the adsorbed O-2 molecules to produce O-2(-center dot). 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 In3+ for Ti4+ enhanced the surface Bronsted acidity and the adsorption of cationic methylene blue. Consequently, In203/CeO2-TiO2 exhibited promising photocatalytic activity in the degradation of methylene blue under visible light irradiation due to the formation of large number of O-2(-center dot) and (OH)-O-center dot radicals. (C) 2015 Elsevier B.V. All rights reserved.