Rapid photocatalytic degradation of selective organic dyes using metal oxide-metal sulphide and its inverted nanocomposites

Abstract

The chemical precipitation approach was employed to synthesize novel heterostructures, namely CeO2-ZnS and SnO2-ZnS, along with inverted nanocomposites ZnS-CeO2 and ZnS-SnO2. The nanocomposites were subjected to characterization using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis absorption spectra, and photoluminescence spectra. The TEM images demonstrated particles that were homogeneous, well-dispersed, and comparatively tiny with a sphere-like structure. This indicates successful synthesis and desirable morphological properties of the nanocomposites. The integration of varied nanoparticles within a heterostructure commonly gives rise to synergistic effects, imparting superior properties to the composite compared to the individual components. These nanocomposites tested for their photocatalytic degradation efficiency using Rose Bengal (RB) and Crystal Violet (CV) dyes under natural sunlight and they exhibited approximately 95 % degradation rate. The degradation results demonstrated a significant enhancement in the photocatalytic efficiency of ZnS-CeO2 and CeO2-ZnS nanocomposites. This improvement was attributed to the effective recombination suppression of photogenerated electron-hole pairs, leading to the generation of highly reactive free radicals. The first-order kinetic rate constant for CeO2-ZnS was determined to be 0.52 min−1 for CV and 0.53 min−1 for RB. The present research work has the potential to offer a novel approach to the construction of new heterojunction photocatalysts and to provide a more profound understanding of the treatment of textile organic dyes.