Enhanced Photocatalytic Activities of Ag[sub.2]WO[sub.4] Modified Ag[sub.6]Si[sub.2]O[sub.7] through a Comprehensive p-n Heterojunction S-Scheme Process

The S-scheme photocatalyst system has become increasingly popular in recent years for its ability to efficiently degrade various pollutants, including organic dyes, pesticides, and other harmful substances. This system uses two semiconductor photocatalysts with different bandgap energies, working together in a redox reaction to produce a highly reactive species capable of pollutant breakdown. Here, an S-scheme Ag[sub.2]WO[sub.4]/Ag[sub.6]Si[sub.2]O[sub.7] p-n heterojunction nanocomposite was successfully developed by a coprecipitation method. By decomposing Rhodamine B (RhB) under visible-light irradiation, the photocatalytic activities of Ag[sub.6]Si[sub.2]O[sub.7]/Ag[sub.2]WO[sub.4] showed enhanced photocatalytic degradation performance of organic dyes, especially at a 4% molar ratio of the Ag[sub.2]WO[sub.4]-modified Ag[sub.6]Si[sub.2]O[sub.7] sample, whose degradation rate was 23.7 and 4.65 times those of Ag[sub.2]WO[sub.4] and Ag[sub.6]Si[sub.2]O[sub.7], respectively. The physical and chemical properties of the samples were determined by identifying the physical structure, chemical element composition, and optical responsiveness. The optimum composite amongst the prepared materials was AgSW-4, achieving the maximum RhB degradation efficiency of 97.5%, which was higher by 60% and 20% than its counterparts Ag[sub.6]Si[sub.2]O[sub.7] and Ag[sub.2]WO[sub.4], respectively. These results showed that in the nanocomposite structure, Ag[sub.6]Si[sub.2]O[sub.7] was a p-type semiconductor and Ag[sub.2]WO[sub.4] was an n-type semiconductor. Based on the analysis data, a comprehensive p-n heterojunction S-scheme process was proposed to demonstrate the enhanced photocatalytic performance of the Ag[sub.6]Si[sub.2]O[sub.7]/Ag[sub.2]WO[sub.4] nanocomposite.