Synthesis, structural and optical properties of Mn Doped ZnO with its photocatalytic activity

Abstract

Metal oxides have emerged as one of the most interesting materials under the Green banner due to its potent catalytic properties. Especially, the II-VI metal oxides are gaining considerable attention in optoelectronics and in rectifying environmental issues due to their ability to produce charge carriers when accelerated with sufficient amount of energy. Zinc oxide and MnXZn(1-X)O were synthesized by co-precipitation method. We present a study of effect of doping on the structural, optical and photocatalytic properties of ZnO. The mean particle size was found to decrease from 20 nm to 11 nm and band gap (Eg) increased from 3.25 eV to 3.68 eV with the increase of doping concentration. This increase in Eg might be ascribed to the alteration of electronic arrangement of ZnO nanoparticles on doping with Mn ions. Photocatalytic reduction was conducted in a home-built reactor assembly and degradation of Cr(VI) to Cr(III) under the presence of UV LED was characterized. In the current work, 15 mol % of Mn doped ZnO (Mn0.15Zn0.85O) nanoparticles showed the better UV response as compared to the other samples. The strong UV response is due to the more 3d orbitals in the valence band owing to an excess amount of Mn dopants in ZnO nanoparticles. The increase in doping concentration of Mn accelerated the photo catalysis. This result indicates that the concentration of Mn is important in controlling the UV response of the samples. The obtained results reveal that both ZnO and MnXZn(1-X)O are promising materials as photo catalysts.