Bismuth sulfide particles were modified with Ag-AgCl nanoparticles to make a visible light active plasmonic photocatalyst. The powder x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), elemental mapping, nitrogen adsorption–desorption isotherms (BET-BJH), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS) techniques were served to analyze the morphological and structural properties. To evaluate the photocatalytic performance, Acid Blue 92 (AB92) azo dye was degraded in the aqueous solution under visible light irradiation. According to the results, 0.025 g of the photocatalyst powder was able to remove more than 98% of AB92 at 15 ppm concentration under neutral acidity, following pseudo first-order kinetics. Superoxide anion radicals (O2•−) were also recognized as the most key species promoting the photodegradation pathway. Also, the antibacterial activity of the materials was explored against E. coli and S. aureus pathogenic bacteria under irradiation and dark conditions. Using transmission electron microscopy (TEM) images of the treated cells, it was found that the plasmonic photocatalyst damaged the cell wall structure of both gram-positive and negative bacteria within 2 h significantly, which could be attributed to the efficient production of destructive superoxide anion radicals on the surface of Ag-AgCl/Bi2S3 particles under illumination.
