Fabrication of polypyrrole-sensitized Ag3PO4/g-C3N4 Z-scheme heterojunction for photocatalytic and antibacterial activity

Charge segregation is crucial for improving photocatalytic activity, and visible light-assisted photocatalysis is an intriguing perspective in the detoxification of environmental contaminants. In this study, a novel Z-scheme polypyrrole sensitized 2D-g-C3N4/Ag3PO4 n-n heterojunction was fabricated by hydrothermal and in situ chemical oxidative polymerization processes at an ambient temperature. The Ag3PO4/PPy/g-C3N4 nanocomposite exhibited superior effectiveness for the degradation of TCH under visible light irradiation (& lambda; & GE; 420 nm) and displayed 95% degradation in 45 min with a rate constant equal to 0.0782 min(-1). The photocatalytic activity of Ag3PO4/PPy/g-C3N4 under visible light irradiation was almost 4.5, 3.2, and 1.5 times as high as those of pure Ag3PO4 and g-C3N4 and binary nanocomposite g-C3N4/Ag3PO4, respectively. In addition, the catalytic activity of the nanocomposite in the reduction of 4-nitrophenol using NaBH4 as a reducing agent was evaluated. The results showed that Ag3PO4/PPy/g-C3N4 exhibited the best performance in the reduction of 4-nitrophenol (4-NP) and revealed 100% conversion into the corresponding amino derivatives in 5 min with a rate constant equal to 0.0127 min(-1). The catalysts also demonstrate excellent antibacterial activity against both Gram +ve and Gram -ve bacteria. The PPy present in the composite acts as an electron acceptor and donor due to its & pi;-& pi; conjugation, which accelerates the rate of electron transfer between Ag3PO4 and g-C3N4 and enhances the segregation of electron-hole pairs, and results in the marvelous photocatalytic activity of Ag3PO4/PPy/g-C3N4. Moreover, the catalyst shows excellent stability even after the use of five consecutive cycles and retained 90% activity without any alteration in its physical appearance.

Automated summary

In this study, a novel Z-scheme polypyrrole sensitized 2D-g-C3N4/Ag3PO4 n-n heterojunction was successfully fabricated, which exhibited superior photocatalytic activity for the degradation of TCH under visible light irradiation. The presence of PPy in the composite accelerated the rate of electron transfer between Ag3PO4 and g-C3N4, enhancing the segregation of electron-hole pairs and resulting in the excellent photocatalytic performance of Ag3PO4/PPy/g-C3N4. Moreover, the catalyst showed excellent antibacterial activity and stability.