Effect of band gap and particle size on photocatalytic degradation of NiSnO3 nanopowder for some conventional organic dyes

Abstract

The present article deals with the study of degradation of organic dyes: congo red (CR), methylene blue (MB) and rhodamin B (RB), using nickel stannate (NiSnO3) nanopowder as photocatalyst. Nanocrystals of NiSnO3 have been synthesized by co-precipitation method. The powder X-ray diffraction (XRD) data taken at room temperature confirms the formation of crystalline phase in NiSnO3. The average particle size, estimated from transmission electron microscopy (TEM) increases from ∼5.05 to ∼8.05 nm with an increase in sintering temperature from 250 to 400 °C. The band gap of the photocatalyst measured (de-ionized water used as eluent) employing Ultraviolet–Visible (UV–Vis) spectroscopy reduces from ∼3.38 to ∼2.90 eV for an identical rise in sintering temperature. The percentage degradation is maximum (∼94%) for CR dye. Among our studied samples, NiSnO3 photocatalyst sintered at 400 °C has the lowest band gap, and the largest average particle size. This shows the best photocatalytic performance. Degradation efficiency of CR dye in various pH ranges (the optimized pH value is ∼5.0) and cyclic stability of the catalyst were also examined. CR dye degradation is ∼92.3% after fifth cycle which is very close to ∼94% degradation of first cycle.