Fabrication of gold nanodots decorated on 2D tungsten sulfide (Au-WS₂) photoanode for simultaneous oxidation of phenol and arsenic (III) from industrial wastewater

Two dimensional (2D) photoelectrocatalysts with a tunable band gap and a large surface area have emerged in recent years for advanced oxidation processes that remove toxic compounds from wastewater. In this study, ultra-thin 2D tungsten sulfide (2D WS₂) photoelectrocatalysts have been fabricated using organosulfur sources, and the resulting 2D WS₂ has high chemical stability and visible light band edges. Additionally, citrate stabilized Au nanodots were successfully incorporated into the 2D WS₂ nanosheets in order to reduces the charge carrier recombination. The morphology, composition, chemical state, and optical properties of the Au-WS₂ photoanodes have been systematically investigated. An Au-WS₂ photoanode is successfully assembled in a photoelectrochemical cell (PEC) for removing phenol and oxidizing toxic As(III) into non-toxic As(V) under visible light. The studies show that the Au-WS₂ photoanode had an oxidation efficiency of 99% for phenol and 95% for As(III) under visible light illumination. Furthermore, X-ray photoelectron spectroscopy (XPS) and theoretical analyses were used to investigate the oxidation pathways of phenol and As(III). A reachability study was carried out to demonstrate that mixed synthetic wastewater containing phenol and arsenite could be used for extended periods in a practical manner. In this study, Au-WS₂ photoanodes were demonstrated to be highly effective in enhancing environmental remediation using advanced oxidation methods.