Photocatalytic degradation of water pollutant dye by solid state synthesized Ni1-xLnxSb2O6 (Ln=Eu, Gd, Ho and Yb) nanocomposites

Nanostructured Ni1-xLnxSb2O6 (Ln = Eu, Gd, Ho and Yb) powders were synthesized via stoichiometric 1:2 Ni:Sb molar ratio by solid state reaction at 800 ºC for 8 h using Ni(NO3)2, Sb2O3, Eu2O3, Gd2O3 and Ho2O3 raw materials. The synthesized materials were characterized by X-ray diffraction (XRD) technique. Structural analyses were done by FullProf program employing profile matching with constant scale factor. The results showed that the patterns had a main orthorhombic NiSb2O6 crystal structure with P42/mbc space group. The morphologies of the synthesized materials were studied by field emission scanning electron microscope (FESEM) which showed that the synthesized samples had sponge morphology. Ultraviolet – Visible (UV-Vis) spectroscopy showed that the smallest direct optical band gap energies were in the ranges of 1.6 to 1.8 eV suggesting a high efficient photocatalytic activity. Photocatalytic performance of the synthesized nanomaterials was investigated for the degradation of pollutant Malachite Green (MG) in aqueous solution under visible light condition. It was found that the optimum conditions were 0.04 mL H2O2, 30 mg catalyst, and 35 min reaction time. It was found that the synthesized NiSb2O6 nanocatalyst had very good efficiency in aqueous solution under the optimized conditions at the presence of visible light irradiation. The degradation yield at the optimized conditions was 96 %. The optimum photocatalytic condition was used to study the performance of the other synthesized materials in the photocatalytic degradation process.