Novel Type-II Heterojunction Binary Composite (CdS/AgI) with Outstanding Visible Light-Driven Photocatalytic Performances toward Methyl Orange and Tetracycline Hydrochloride

In this study, an effective type-II heterojunction CdS/AgIbinarycomposite was constructed by an in situ precipitationapproach. To validate the successful formation of heterojunction betweenAgI and CdS photocatalysts, the synthesized binary composites werecharacterized by various analytical techniques. UV-vis diffuse-reflectancespectroscopy (UV-vis DRS) revealed that heterojunction formationled to a red shift in the absorbance spectra of the CdS/AgI binarycomposite. The optimized 20AgI/CdS binary composite showed a leastintense photoluminescence (PL) peak indicating highly improved chargecarrier (e(-)/h(+) pairs) separation efficiency.The photocatalytic efficiency of the synthesized materials was assessedbased on the degradation of methyl orange (MO) and tetracycline hydrochloride(TCH) in the presence of visible light. Compared to bare photocatalystsand other binary composites, the 20AgI/CdS binary composite showedthe highest photocatalytic degradation performances. Additionally,the trapping studies showed that superoxide radical anion (O-2 (center dot-)) was the most dominant active speciesinvolved in photodegradation processes. Based on the results of activespecies trapping studies, a mechanism was proposed to describe theformation of type-II heterojunctions for CdS/AgI binary composite.Overall, the synthesized binary composite has tremendous promise forenvironmental remediation due to its straightforward synthesis approachand excellent photocatalytic efficacy.