Photocatalytic Study of Mo/N co-doped Titanium Dioxide (TiO2) Nanoparticles Under Visible Light Irradiation

Abstract

Undoped TiO₂ and Mo/N co-doped TiO₂ nanoparticles have been fabricated by sol gel technique. The average particle size of nanoparticles was calculated from the line broadening of (101) peak of XRD pattern and further verified by High Resolution Transmission Electron Microscopy (HRTEM) are in good agreement. The decrease in particle size 28.5 to 15.0 nm was observed with increase of molybdenum concentration. The surface morphology of all samples was studied by Field Emission Scanning Electron Microscopy shows small agglomeration. The optical band gap energy was calculated using UV-visible absorption spectroscopy and found to decrease in increase of doping concentration.  The presence of defect levels caused by oxygen vacancies has been confirmed by Photoluminescence spectra. The emission bands observed at 453.9, 470.6, 485.7, 495.8 and 535 nm could be arising from surface states. The phase composition and elemental analysis of synthesized samples was estimated from Energy dispersive X-ray spectroscopy.  The effect of doping concentration on structural formation was studied by FTIR spectroscopy. The Photocatalytic activity of synthesized samples for degradation of Congo red (CR) and Methyl orange (MO) dyes as standard pollutants was investigated under visible light source. The increase in doping concentration causes enhance in photocatalytic activity of the synthesized nanoparticles which is attributed from the decrease in electron-hole pair recombination rates. The degradation efficiency against congo red dye is very high compared to methyl orange dye. These observations suggest that co-doped synthesized nanoparticles are suitable for complete degradation of congo red dye and are not able to degrade methyl orange dye.