Structural, optical and photocatalytic study of Sr2+ doped TiO2 nanoparticles

Abstract

Sr2+ doped TiO2; SrxTi1−x O2; x = 0.12, 0.16 & 0.20 mol % nanoparticles have been synthesized by hydrothermal method. The X-ray diffraction (XRD) data analysis confirms the formation of mixed anatase phase of strontium doped TiO2 nanoparticles. The crystallite size vary from 35.4 nm to 25.5 nm was estimated from the FWHM of (101) peak of TiO2 in X-ray diffraction spectra. The UV-Vis absorption spectroscopy was used to determine optical band gap energy and calculated values to be 2.96, 2.57 & 2.37 eV respectively. The formation of defect levels caused by oxygen vacancies were confirmed by Photoluminescence spectroscopy. The emission bands observed at 453, 464, 470, 483 and 494 nm in photoluminescence spectra could be arising from surface states appears in forbidden region of TiO2. The effect of doping on structural formation is verified by Fourier-transform-infrared spectroscopy. The photocatalytic degradation efficiency of synthesized nanoparticles against both dyes congo red and methyl orange (both used as model pollutant) was studied under visible light source of wavelength ranging 400-700 nm and found to increase with increase in dopant concentration. The increase in photocatalytic degradation activity of synthesized nanoparticles is attributed to decrease in photo induced charge carrier recombination rate arises from the decrease in energy band gap.