Effect of adsorption on photocatalytic activity for rhodamine B degradation of copper-doped tungsten disulfide

Abstract

In this study, the Cu-doped WS₂ materials were synthesized by a simple solid-state calcination of mixture of tungstic acid, thiourea and copper (II) acetate monohydrate in Ar gas at 650 ^oC for 1h, and denoted as xCu-WS₂, where x is atomic percentage ratios of Cu/W (x= 1, 3, 5%) and weigh ratio of tungstic acid/thiourea is constant (1:5). The obtained products were characterized by X-ray diffraction, infrared, energy-dispersive X-ray spectroscopy, scan electron microscopy and UV-Vis diffuse reflectance spectroscopy. The photocatalytic performance of the samples was assessed through photodegradation of rhodamine B (RhB). Interestingly, there is a synergistic relationship between adsorption and photocatalysis, in which, a higher relative adsorption might give a better photocatalytic results due to reactive species reacting with absorbed organic matter on the catalyst surface rather than in the bulk of solution. The photodegradation of RhB over the 1Cu-WS₂ catalyst was enhanced significantly with the highest efficiency up to 95.35% at pH 8 for 6 hours of visible light irradiation, which is attributed to the high adsorption of RhB cationic dye on the material surface. The photocatalytic mechanism was discussed as well.