Modified silver phosphate nanocomposite as an effective visible-light-driven photocatalyst in the reduction of aqueous Cr(VI)

A simple precipitation technique was used to synthesize novel modified Ag3PO4 (AP) with Ag2S (AS) and reduced graphene oxide (G). XRD, FT-IR, Raman spectra, HR-TEM, XPS, UV-Vis, and PL, were used to investigate the physicochemical and optical properties of the as-prepared materials. The produced AS/G/AP nanocomposites exhibited a more visible-light response, diminished bandgap energy, and enhanced the charge separation rate. For the first time, the photocatalytic efficiency of modified Ag3PO4 nanocomposites was tested in aqueous Cr(VI) reduction under visible light illumination. After 45 min of irradiation and adapting the dose to 0.05 g/L, the optimized composite with 20 wt%AS (20-AS/G/AP) attained the maximum photo-reduction efficiency of 98.7% for Cr(VI) with a rate constant of 0.0734 min-1, which is almost 49 times higher than pure AP. The XPS analysis of the spent catalyst confirmed the distinctive Cr(III) peaks. Moreover, the photocatalyst showed notable reus-ability for four cycles without substantial activity loss. Finally, the photo-reduction mechanism of the catalyst was suggested.