DMSO- mediated solvothermal synthesis of S/AgX (X = Cl, Br) microstructures and study of their photocatalytic and biological activity

Abstract

Microstructures with different content of sulfur (S) and silver halides (AgX, X = Cl, Br) were obtained by DMSO-mediated solvothermal synthesis with using of two methods: 1) precipitation of S at room temperature and 2) precipitation of S with water. The XRD and Raman analysis has shown the presence of S and AgX phases. The SEM analysis have displayed that S/AgX microstructures are represented by agglomerates of S with irregular form with 25–50 µm in size, which are mostly covered by spherical particles of AgX with size range from 0.7 to 2 µm. These results were proved by TEM elemental mapping. TEM analysis also showed the presence of the dense micron-sized aggregates of particles from 5 to 100 nm with highly developed system of dense intergrain boundaries for S/AgCl sample, while S/AgBr sample was represented by large aggregates of crystalline particles and an amorphous matrix. Obtained microstructures exhibited low specific surface area. XPS revealed the presence of metallic silver on the surface of all samples due to partial photoreduction. Its content was much higher when sulfur was precipitated at laboratory temperature. According to TGA-DSC analysis the actual composition of the microstructures corresponds to the desired content. The samples with the highest content of AgX were able to degrade from 70 to 90 % of molecules of Orange II, after 180 min of visible light irradiation. Up to 5 cycles, almost similar photocatalytic activity could be retained for all the samples. The majority of the samples exhibited antimicrobial activity, namely they were active in suppression of the S. aureus ATCC 6538-P, E. coli ATCC 8739, C.albicans ATCC 10231, P.aeruginosa ATCC 9027, Erwinia amylovora, S. aureus ATCC BAA-39 and E. coli ATCC BAA-196 strains.