Experimental and theoretical investigations of Mn-N-co-doped TiO2 photocatalyst for visible light induced degradation of organic pollutants

Abstract

The present paper reports the experimental and theoretical investigations of Mn-N-co-doped TiO2 photocatalyst for degradation of organic pollutants. Mn-N-co-doped TiO2 photocatalyst was synthesized by using cavitation induced technique and the incorporation of dopant (Mn2+) ion in the lattice of N-doped TiO2 and was confirmed from X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray spectrometry (EDS), Fourier transform infrared (FTIR), Raman, UV–vis and Electron paramagnetic resonance (EPR) spectroscopy. The effect of Mn2+ ion on variation in structural, morphological and optical properties of catalyst was assessed. The photocatalytic response of the Mn-N-co-doped TiO2 catalyst was investigated at different wavelength regions (490 nm, 565 nm, and 660 nm) of the solar spectrum for the degradation of organophosphate pesticides quinalphos and 2- chlorophenol. The present study has highlighted the photocatalytic efficiency of the Mn-N-co-doped TiO2 photocatalyst. To understand the photocatalytic activity at the molecular level, the adsorption energies (ΔEad) of quinalphos and 2-chlorophenol with the N-doped TiO2 and Mn-N-co-doped TiO2 photoctalysts were calculated with density functional theory (DFT) using B3LYP (Becke’s 3-parameter exchange functional with Lee-Yang-Parr correlation energy) functional and 6-311 G(d,p)/LANL2DZ basis set. The obtained ΔEad values indicated the probable positions on the surface of photocatalysts where pesticide molecules could adsorb and degrade efficiently. The computational study can be used for comprehensing the mechanism of degradation of pollutant molecules in the presence of photocatalysts. Keywords: Mn-N-co-doped TiO2, Density functional theory (DFT), Photodegradation, Quinalphos, 2-chlorophenol