Highly efficient sunlight-driven photodegradation of industrial dyes by Ni-, Cu-, and Zn-doped MgO nanopowders

This study provides the first ever investigation of the influence of nickel, copper, and zinc additives upon magnesium oxide powders when synthesized via sol–gel autocombustion. In order to assess the resulting properties of the samples affected by the addition of Ni, Cu, and Zn ions, a number of investigative techniques were employed, among which were X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet (UV)–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, and vibrating sample magnetometry (VSM). From XRD results, it was apparent that when Ni, Cu, and Zn ions are added to MgO, cubic solid solutions of NiMgO, CuMgO, and ZnMgO are created. UV-DRS analysis showed significantly improved absorption levels in the samples that were optimally modified compared to the pure sample across UV, visible, and infrared spectral observations. Analysis of the photocatalytic activity exhibited by the synthesized samples was performed by considering the decomposition under sunlight of rhodamine B, methylene blue, methyl orange, and methyl red. The degradation under sunlight for these organic dyes was shown to be superior to that of pure MgO, achieving a range of 91%–95% in just 150 min.