Synthesis and photocatalytic activity of Ni doped SnO2 nanoparticles for removal of toxic industrial dyes

Metal oxide semiconducting material like SnO2 has novel features like wide band gap (3.6 eV) and large exciton binding energy (130 meV) which ensure its promising optoelectronic applications. In the present work, we have carried out a detailed study on the above materials i.e. SnO2 and Sn1-xNixO2 which were synthesized using sol-gel method with stannous chloride, nickel nitrate hexahydrate, ammonium hydroxide and isopropyl alcohol as the starting materials. Ostudy confirms that SnO2 and Ni-SnO2 samples are of tetragonal structure with crystal size 32 nm and 28 nm respectively as estimated from Scherrer formula. The optical band gap of pure tin oxide is found to be 3.73 eV from UV-Vis absorption measurements which shifts to 3.70 eV for Ni-SnO2. The PL spectra show several emission bands at 418 nm, 437 nm, 463 nm, 487 nm and 530 nm in the visible region. These bands are ascribed to the defect emissions arising due to oxygen vacancies. With Ni doping, the intensity of these bands increases which may be due to the increase in the density of the above defects. The photocatalytic degradation of Congo red (CR) dye was studied by irradiating UV-Vis light source and found the degradation efficiency of 83% for Ni-SnO2 sample which was 74% for the pristine sample. Ni doping helps to enhance the light absorp-tion ability of SnO2 leading to better degradation efficiency. (C) 2022 Elsevier Ltd. All rights reserved.