Synthesis and Characterization of ZnO-ZnS Nanoflowers for Enhanced Photocatalytic Performance : ZnS Decorated ZnO Nanoflowers

Abstract

ZnO nanoflowers were synthesized using simple wet chemical approach, upon which nanoscale ZnS was deposited through pseudo successive ionic layer adsorption and reaction (p-SILAR). The process was optimized by increasing the number of p-SILAR cycles. The average size of ZnO nanoflowers was determined using particle size analysis technique and was found to be 600 nm. The morphology of resultant ZnO-ZnS nanoflowers was analyzed using field emission scanning electron microscope (FESEM). Energy dispersive spectroscopy (EDS) not only confirmed the presence of zinc, oxygen, and sulphur as major elements, but it also showed a linear increase in sulphur percentage with increasing number of p-SILAR cycles, i.e. 4.76%, 5.21% and 7.64% corresponding to 4, 6 and 8 p-SILAR cycles. The uniform distribution of ZnS over ZnO nanoflowers was observed through elemental area mapping. The crystallinity and phase purity of ZnO-ZnS nanoflowers was characterized using X-ray powder diffraction (XRD) spectroscopy. Moreover, owing to the proficient ultraviolet (UV) light absorbing tendency of ZnO and ZnS, dye degradation test was performed to compare the photocatalytic performance of ZnO-ZnS nanoflowers. It was found that ZnO-ZnS nanoflowers prepared using 6 p-SILAR cycles produced a maximum of 91.5% degradation (~13% higher than ZnO) of congo red dye when exposed to UV light for 40 min.