Preparation of SnO2 Nanoparticles with Addition of Co Ions for Photocatalytic Activity of Brilliant Green Dye Degradation

Pure and cobalt (Co)-doped tin oxide (SnO2) nanoparticles were prepared by using a simple co-precipitation method, and the effect of doping on structural, morphological and optical properties was studied. X-ray diffraction revealed a cassiterite tetragonal SnO2 structure with the space group of P42/mnm and without crystalline phases for the samples-doped with higher concentrations. The average crystalline size was found to be between 26.4 nm and 23.1 nm. Fourier-transform infrared spectra depicted the presence of O–H, C–H and Sn–OH absorption bands. It was observed from ultraviolet–visible spectra that the optical band gap values were decreased from 3.69 eV for pure SnO2 to 3.47 eV for 7% Co-doped SnO2. The photolumenescene emission spectra showed that the defect- and emissions-related peaks and the intensity of the peaks decreased with increasing Co concentrations. The presence of tin, oxygen and Co species were found from energy dispersive x-ray spectra. The photocatalytic activities of pure and Co-doped SnO2 nanoparticles were investigated by studying the photodecomposition of brilliant green dye, an organic pollutant. The 7% Co-doped SnO2 had higher photocatalytic activity compared to the pure SnO2, and a maximum degradation efficiency of 91% has been obtained under visible light irradiation.