Enhanced photocatalytic activity of nitrogen and indium co-doped mesoporous TiO2 nanocomposites for the degradation of 2,4-dinitrophenol under visible light

Abstract

Mesoporous N/In2O3–TiO2 nanocomposite photocatalysts were synthesized by sol-gel route using Pluronic P123 as the structure directing template. The synthesized composite materials were successfully characterized by X-ray powder diffraction, high resolution transmission electron microscopy, N2 adsorption–desorption studies, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis spectroscopy, Fourier transform infrared spectroscopy and photoluminescence spectroscopy. The photocatalytic activities of all the synthesized catalysts were evaluated for the degradation of 2,4-dinitrophenol under visible light irradiation. The results demonstrated that the mesoporous N/In2O3–TiO2 showed higher efficiency than meso TiO2, N-TiO2 and In2O3–TiO2 under visible light irradiation and the optimum molar ratio of N and In to Ti is 0.3wt%. DRUV–vis revealed that the substitution of N− and In3+ dopants on TiO2 lattice shifted the light absorption to the longer wavelength and reduced the band gap energy. The enhanced •OH radicals formation during the photocatalytic reaction was revealed by photoluminescence spectra. The photoluminescence spectra of synthesized catalysts revealed that the efficient charge separation of photo induced charge carriers for 0.3wt% N/In2O3–TiO2 nanocomposite. The enhanced surface area, large pore volume and large pore diameter for 0.3wt% N/In2O3–TiO2 improved the photocatalytic efficiency. In3+ ions can easily trap and transfer the excited electrons to the adsorbed O2 molecules, hence efficiently extending the life time of electron–hole pair.