Preparation of CdS-Ag2S nanocomposites by ultrasound-assisted UV photolysis treatment and its visible light photocatalysis activity

Abstract

Thiosulfate is a green leaching agent used in the hydrometallurgical process because it is both environmentally benign and can form the required soluble ion complexes. In this article, a novel method for the synthesis of CdS-Ag2S nanocomposites from a solution of relevant ion complexes via ultrasound-assisted ultraviolet (UV) photolysis was proposed. An analysis of the mechanism revealed that the complexes undergo a series of photochemical reactions. The CdS-Ag2S nanocomposites were synthesized by photochemical co-precipitation under UV-C irradiation. The microstructure, chemical composition, optical and electrochemical properties of the prepared nanocomposites were analyzed to verify the synthesis and investigate the product. The photodegradation of methyl orange (MO) under a xenon lamp was performed to determine the photocatalytic activity. Under visible light irradiation, the CdS-Ag2S nanocomposites undergo the electrons transition (from valence band to conduction band) to form photogenerated electron-hole pairs realizing the effective separation of carriers and finally promote the degradation of MO to water and carbon dioxide. The subsequent degradation efficiency of the CdS-Ag2S nanocomposites was found to be 87% after 90 min, and it was larger than 78% for pure CdS prepared via UV photolysis, indicating that the as-developed novel method can effectively fabricate CdS-Ag2S photocatalyst with superior performance.