Sublimable xanthate-mediated solid-state synthesis of highly interspersed g-C3N4/Ag2S nanocomposites exhibiting efficient bactericidal effects both under dark and light conditions

Abstract

The synthesis of exotic nanocomposites (NCs) comprising of highly dispersed metal sulfides is challenging owing to the formation of crystalline sulfides in the conventional wet-impregnation method and sublimation characteristics of the sulfide precursors in the thermal decomposition method. Here, we employ silver amyl xanthate (Ag-Xn) precursor to demonstrate a scalable solid-state synthesis of highly interspersed metal sulfide/g-C3N4 NCs. Two strategies, namely, (i) a one-step thermal decomposition of a mixture containing intimately mixed melamine and Ag-Xn, and (ii) a two-step method in which Ag-Xn is intimately mixed with a pre-synthesized g-C3N4 followed by thermolysis, have been explored. The characterization studies revealed a high degree of amorphization of Ag2S due to its high interspersion in the g-C3N4 matrix. Among the two strategies, the two-step method has yielded higher metal loading than the one-step method and correspondingly higher efficacy in the photodegradation of methylene blue. The incorporation of Ag2S in g-C3N4 has effectively modified the density of states and minimized the electron-hole pair recombination in the optimal composition, and thereby enhanced the photocatalytic activity. The studies over Staphylococcus aureus and Escherichia coli have revealed that the two-step method NCs exhibit good bactericidal efficacy under dark and remarkable activity under visible light irradiation conditions.