Design Ag-doped ZnO heterostructure photocatalyst with sulfurized graphitic C₃N₄ showing enhanced photocatalytic activity

Highly efficient Ag-doped ZnO (Ag-ZnO)/sulfurized graphitic C₃N₄ heterostructure photocatalyst was synthesized in a two-step hydrothermal route. Initially, Ag (1–9%) was doped into ZnO nanostructure and checked photocatalytic properties. 7% Ag-doped ZnO (7Ag-ZnO) NPs shown best photocatalytic methylene blue (MB) dye degradation under visible radiation, so, it was selected for forming composite with S-g-C₃N₄. In 1st step, S-g-C₃N₄ was synthesized by calcinating. In the 2nd step, 7Ag-ZnO/S-g-C₃N₄ heterostructure photocatalyst was formed by in situ formation of 7Ag-ZnO NPs in the presence of different contents of S-g-C₃N₄ (3.5–75 wt%) through hydrothermal route. As a result of 7Ag-ZnO/S-g-C₃N₄ heterostructure, a large number of catalytic active sites were generated for photocatalytic degradation. Interestingly, the 7% Ag-ZnO nanoparticles (NPs) with 25% S-g-C₃N₄ exhibited 97% MB degraded within 40 min, which was degraded up to 57% by 7Ag-ZnO alone. Moreover, the photo corrosion of ZnO NPs was inhibited by doping with Ag and coupling with S-g-C₃N₄.