Magnetic grinding synthesis of copper sulfide-based photocatalytic composites for the degradation of organic dyes under visible light

We demonstrate a low-cost, simple-operation, and environmentally friendly magnetic grinding synthetic process to prepare nontoxic copper sulfide-based composites with photocatalytic activity. Using this efficient approach, CuS/ZnS and CuS/CdS composites were successfully synthesized from elemental powders without using any other additives or solvents. The formation of metal sulfides was confirmed using a series of characterizations. The photocatalytic activities of the as-prepared materials were evaluated by the degradation of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) dyes in the presence of hydrogen peroxide (H2O2), which served as an oxidant under visible irradiation. The degradation efficiencies of MB and RhB by CuS/ZnS and CuS/CdS composites were more than 95% in 30 min and the degradation efficiency of MO was more than 85% in 90 min. The photocatalytic activities of the CuS/ZnS and CuS/CdS composites were better than those of pure metal sulfides. In addition, the CuS/ZnS and CuS/CdS composites showed good stability toward photocatalytic degradation and their main reactive species for degrading organic dyes are photogenerated hydroxyl radical (OH). Reasonable photocatalytic reaction mechanisms are proposed to explain the photocatalytic processes of the CuS/ZnS and CuS/CdS composites.

Automated summary

We present a cost-effective, easy-to-operate, and environmentally friendly magnetic grinding synthesis process for producing non-toxic copper sulfide-based composites with photocatalytic activity. CuS/ZnS and CuS/CdS composites were successfully synthesized without the need for additives or solvents. The composites exhibited high photocatalytic activity in the degradation of dyes under visible irradiation, with degradation efficiencies exceeding 95% for methylene blue and rhodamine B, and over 85% for methyl orange. The CuS/ZnS and CuS/CdS composites demonstrated superior photocatalytic performance compared to pure metal sulfides, and showed good stability in the degradation of organic dyes. The main reactive species responsible for the degradation were identified as photogenerated hydroxyl radicals (OH). Reasonable photocatalytic reaction mechanisms were proposed to explain the processes involved in the CuS/ZnS and CuS/CdS composites' photocatalytic activity.