Harnessing Synergy in g-C3N4/ZnO/PPy Nanocomposite for Efficient Photocatalytic Degradation of Phenolic and Antibiotic Pollutants

The study introduces an innovative Z-scheme heterojunction g-C3N4/ZnO/PPy (GZP) nanocomposite synthesized through a three-step process: calcination, coprecipitation, and in situ polymerization of polypyrrole (PPy), with varied PPy concentrations (0.5%, 1%, 2%, 3%, and 4%). Extensive characterizations confirmed the successful integration and uniform dispersion of ZnO and PPy on the g-C3N4 matrix, enhancing surface interaction and structural stability. FTIR confirmed the successful incorporation of PPy and ZnO on the g-C3N4, while XRD and XPS provided insights into the crystalline structure and elemental composition. TEM and SEM revealed uniform dispersion of ZnO and PPy, ensuring optimal surface interaction. UV-DRS analysis showed enhanced visible light absorption, while PL spectra demonstrated effective suppression of charge carrier recombination, with EIS indicating reduced charge transfer resistance, thus promoting superior separation and transport of photogenerated carriers. Photocatalytic evaluations highlighted the remarkable efficiency of GZP1 achieving 97% degradation of Rose Bengal (RB) and 93% degradation of sulfamethoxazole (SMZ) at a low concentration of 10 mg/100 mL, with consistent performance over four cycles. Active species analysis identified holes (h(+)) and hydroxyl radicals ((OH)-O-center dot) as the key contributors to degradation. These results establish GZP as a promising photocatalyst with high reusability and efficiency, addressing critical water purification challenges.