Phenol and Cr(vi) degradation with Mn ion doped ZnO under visible light photocatalysis

Abstract

Mn ion doped ZnO with different percentages of Mn content (Zn_0.9Mn_0.1O (1), Zn_0.8Mn_0.2O (2), Zn_0.7Mn_0.3O (3), and Zn_0.6Mn_0.4O (4)) was synthesized via a solution combustion method, with urea used as the fuel. The optical, morphological, and structural properties were studied using Raman, UV-DRS, SEM, TEM, XPS, and powder XRD techniques. The average crystallite sizes of Zn_1−xMn_xO (1, 2, 3, 4), which are around 30–60 nm, were confirmed via powder X-ray diffraction studies, whereas transmission electron microscopy studies confirmed the formation of a ZnO wurtzite crystal phase. Scanning electron microscopy indicated the spherical morphology of the samples. Raman spectroscopy studies confirmed a decrease in oxygen vacancies with increasing Mn content, whereas confirmation of the doping of Mn ions into the ZnO lattice was obtained using X-ray photoelectron spectroscopy. The band gap energies of samples were calculated using UV-DRS spectroscopy, whereas BET surface area measurements confirmed the surface area. The visible light activity of Zn_1−xMn_xO (1, 2, 3, 4) was identified through studies of phenol degradation and Cr(VI) reduction under visible light photocatalysis, which highlight that Zn_0.8Mn_0.2O (2) shows the best activity. Typical degradation profiles indicated that the simultaneous degradation of pollutants is more effective than the removal of individual pollutants.