Application of Z–Scheme CdS- WO₃ Nanocomposite for Photodegradation of Ethylparaben under Irradiation with Visible Light: A Combined Experimental and Theoretical Study

The CdS (Formula presented.) WO₃ nanocomposite was successfully synthesized using the hydrothermal method. The catalytic capacity of CdS (Formula presented.) WO₃ nanocomposite was evaluated based on various parameters, such as pH, catalyst load, bicarbonate and persulfate concentrations. The ratios of CdS to WO₃ was also examined to acquire the photocatalytic performance in addition, the by–products and pathway were also studied. The findings showed that CdS (Formula presented.) WO₃ (ratio 3:7) produced better photodegradation performance in comparison to CdS (Formula presented.) WO₃ (ratio 1:1). Also, from the same investigation, the CdS (Formula presented.) WO₃ nanocomposite exhibited a slightly higher catalytic ability in the presence of 150 mg L^–1 S₂O₈ ^2– ions (at pH 3) than with bicarbonate ions. A 40% degradation was observed in the presence of 150 mg L^–1 S₂O₈ ^2– ions (at pH 3). Moreover, about 38% of adsorption was observed with bicarbonate ions. In this study, we systematically reveal the underlying mechanism of the improved photoactivity of CdS–WO₃ nanocomposite using a hybrid density functional theory calculation. The interfacial interaction led to the formation of a built–in internal electric field at the CdS–WO₃ interface to promote the separation of charge carriers, The theoretical results rationalise the experimental findings and offer a new understanding of the underlying mechanism of the photoactivity of CdS–WO₃ nanocomposite. The degradation pathway of Ethylparaben, which involved dealkylation of ethyl unit was proposed.