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

Mn ion doped ZnO with different percentages of Mn content (Zn0.9Mn0.1O (1), Zn0.8Mn0.2O (2), Zn0.7Mn0.3O (3), and Zn0.6Mn0.4O (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 Zn1-xMnxO (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 Zn1-xMnxO (1, 2, 3, 4) was identified through studies of phenol degradation and Cr(VI) reduction under visible light photocatalysis, which highlight that Zn0.8Mn0.2O (2) shows the best activity. Typical degradation profiles indicated that the simultaneous degradation of pollutants is more effective than the removal of individual pollutants.