In Situ Formation of Leaf-Like Ag2S/CdS Heterojunction Photocatalyst Harnessing Vis–NIR Light for Photodegradation of Organic Pollutants

Abstract

The Ag2S/CdS composite photocatalyst with a leaf-like structure was synthesized by loading the Ag2S nanoparticles on the surface of the hydrothermally synthesized CdS particles. The UV–Vis–NIR absorption spectroscopy results reveal that the Ag2S/CdS composite photocatalyst exhibits a wide-spectrum response from ultraviolet (UV) to near-infrared (NIR), demonstrating its potential for effective utilization of solar energy. The scanning and transmission electron microscopic observations show that Ag2S nanoparticles with the size of about 20 nm are successfully embedded on the surface of leaf-like structure of CdS. Among the samples loaded with different molar percentages of Ag2S nanoparticles, the 5%-Ag2S/CdS composite photocatalyst exhibits a higher photocatalytic efficiency than the individually synthesized CdS and Ag2S for the degradation of Rhodamine B (RhB) and methyl orange (MO) under LED visible light irradiation. Furthermore, the 5%-Ag2S/CdS composite photocatalyst also exhibits a photocatalytic activity for the degradation of RhB under 850 and 940 nm monochromatic light irradiation. The results of the photocatalytic activity tests performed with various scavengers confirm that ·O2− plays a key role in the photodegradation of RhB. An enhanced photocatalytic performance of the Ag2S/CdS composite photocatalyst is directly attributed to the formation of a heterojunction between Ag2S and CdS. The developed composite photocatalyst can harness a greater share of the solar spectrum from visible to near infrared region and generate the photoinduced charge carriers more efficiently.