Efficient sunlight-driven photocatalytic behavior of zinc sulfide nanorods towards Rose Bengal degradation

Abstract

In this study, zinc sulfide nanorods (ZSNRs) were successfully synthesized by the solvothermal route. The structural, morphological, elemental composition, chemical state, surface charge, particle size, optical and electrochemical characterizations using powder X-ray diffraction (P-XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, dynamic light scattering (DLS), UV–Vis spectroscopy, steady-state and time-resolved photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and Mott–Schottky (MS) confirmed that the prepared zinc sulfide (ZnS) exhibits hexagonal wurtzite structure, rod-like morphology, excellent optical absorption, fast charge carrier decay, surface charge transfer behavior, and flat band potential. The photocatalytic performance of prepared ZSNRs photocatalyst was tested by monitoring the degradation of Rose Bengal (RB) dye aqueous solution under direct sunlight irradiation. The effects of catalyst dosage and dye concentration were also considered for the effective degradation of RB dye. The optimum catalyst dosage and concentration of dye were found to be 0.02 mg/mL and 10 µM, respectively. A maximum of 93% photocatalytic degradation efficiency (DE%) was achieved at 60 min of direct sunlight irradiation. The standard deviation in photocatalytic performance is found to be ± 0.89%. From the reactive species trapping experiment, the photocatalyst performance of RB dye over ZSNRS mainly depends on the species of holes and hydroxyl radicals rather than electrons and superoxide radicals. A 0.72 ± 0.09 quantum yield for the photodegradation reaction of ZSNRs was noticed. To the best of our knowledge, the present work is the first study to utilize ZSNRs as a photocatalyst for the effective degradation of RB dye.