Improved charge carrier dynamics of WS2 nanostructures by the way of CdS@WS2 heterostructures for use in water splitting and water purification

Abstract

Heterostructures consisting of tungsten disulfide (WS₂) and cadmium sulfide (CdS) have shown longer emission decay life time and significantly quenched fluorescence emission in comparison to pure materials (WS₂ and CdS). CdS@WS₂ heterostructures also show a significant enhancement in light absorption across the entire visible spectrum with a change in the slope of the absorption edge pertaining to WS₂ nanostructures in the heterostructures. This leads to higher number of charge carriers, improved charge separation as well as charge migration from the material surface to the back contact. In photoelectrochemical water splitting, the heterostructures exhibited a twentyfold increase in photocurrent density (0.15 mA cm⁻²) at 1.23 V vs. RHE in comparison to pristine sulfides. The heterostructures also showed a good reduction ratio of >83% in 120 minutes [Cr(VI) to Cr(III)] in a mixture of Cr(VI)/Ni(II) ions and RhB. Hence, CdS@WS₂ heterostructures with improved charge carrier dynamics can find several applications as photocatalysts.