Boosted photocatalytic degradation of Rhodamine B pollutants with Z-scheme CdS/AgBr-rGO nanocomposite

Abstract

High-efficiency photocatalytic degradation of a harmful organic pollutant, i.e., Rhodamine B (RhB), was achieved using an rGO-mediated CdS/AgBr (CdS/AgBr-rGO) photocatalyst composed of AgBr, CdS and reduced graphene oxide (rGO). The batch experiments demonstrated that the first-order kinetic constants of as-synthesized photocatalyst prepared CdS/AgBr-rGO with a mass ratio of 10:1:0.005 was 0.051 min−1. The value was 1.96 and 5.67 times higher than those of CdS and AgBr alone for RhB degradation, respectively. Using benzoquinone (BZQ), isopropyl alcohol (ISA) and ethylenediamine tetraacetic acid disodium salt (Na2-EDTA) as scavengers, the results of quenching experiment indicated that O2−, OH and h+ are the dominant reactive species for RhB decomposition. The electrochemical analysis demonstrated that CdS and AgBr formed a Z-scheme photocatalytic system via rGO at the interface of the two semiconductors acting as a solid electron shuttle where the photogenerated electron-hole pairs were efficiently separated through electron transfer. Furthermore, the photostability of CdS/AgBr-rGO heterojunction photocatalysts was investigated over four successive runs.