Functionalized MoS2 supported core-shell Ag@Au nanoclusters for managing electronic processes in photocatalysis

Metal nanoclusters (M_NCs) based on gold as core and silver as shell, abbreviated as Ag@Au_NCs, were electrostatically associated with functionalized semiconducting MoS₂ nanosheets, abbreviated as f-MoS₂. The realization of the Ag@Au_NCs/f-MoS₂ ensemble was manifested by UV–vis and photoluminescence titration assays, while its morphology was evidenced by high-angle annular dark-field STEM imaging coupled with EDX analyses. Photoinduced intra-ensemble charge-transfer phenomena were witnessed and attributed to the suppression and concomitant shift of Ag@Au_NC photoluminescence by incremental additions of f-MoS₂. The Ag@Au_NCs/f-MoS₂ was employed as RhB photodegradation catalyst for wastewater purification from organic pollutant dyes. The production of highly oxidant radicals from the photogenerated electron-hole pairs within Ag@Au_NCs/f-MoS₂ were found to be the main reactive species, while the holes left on Ag@Au_NCs attacked RhB, as evidenced by the disappearance of the characteristic absorption peak. The photocatalytic reaction by the ensemble followed fast kinetics as compared with bare Ag@Au_NCs or individual Au_NCs and Ag_NCs.