Efficient decontamination of textile industry wastewater using a photochemically stable n-n type CdSe/Ag3PO4 heterostructured nanohybrid containing metallic Ag as a mediator

Abstract

To address the environmental hazard posed by the discharge of textile industry wastewater, we combined n-type (CdSe) and n-type (Ag₃PO₄) visible-light-responsive semiconductors to produce a photochemically stable n-n type heterostructured nanohybrid comprising metallic Ag (CdSe/Ag/Ag₃PO₄, CAA) and employed this material as a catalyst for the decomposition of phenol and rhodamine B (RhB). The physicochemical properties of CAA and reference photocatalysts were investigated using instrumental techniques. Compared to individual Ag₃PO₄ and CdSe, CAA showed an elevated photocatalytic decomposition efficiency for both target pollutants, which was mainly attributed to increased charge separation efficiency and explained by the operation of the Z-scheme reaction mechanism. Moreover, we probed the effects of initial pollutant concentration, AgNO₃:NaH₂PO₄ molar ratio, and the CdSe:Ag₃PO₄ mass ratio of CAA on catalytic performance. Recycling tests revealed the high photochemical stability of CAA, which was ascribed to the prevention of Ag₃PO₄ photoreduction by electrons. Finally, a Z-scheme mechanism with vectorial charge transfer suggested for the visible-light-driven decomposition of pollutants over CAA nanohybrids was systematically discussed based on the results of scavenger tests and photoluminescence emission spectra analysis, and an explanation of the role of metallic Ag as a charge mediator was provided.

Keywords: Photochemical stability; Vectorial charge transfer; Water waste decomposition; Z-scheme mechanism; n–n Type hybrid.