Protonated graphitic carbon nitride/polypyrrole/reduced graphene oxide composites as efficient visible light driven photocatalysts for dye degradation and E. coli disinfection

• Published in: Journal of alloys and compounds 2021-08, Vol.873, p.159750, Article 159750
• Main Authors: Liu, Shiben, Jiang, Xiaohui, Waterhouse, Geoffrey I.N., Zhang, Zhi-Ming, Yu, Liang-min
• Format: Article
• Language: English
• Subjects: Accumulation; Carbon nitride; Composite materials; Conduction bands; Deactivation; Degradation; Disinfection; Dyes; E coli; Efficiency; Electrons; Graphene; Heterojunctions; P-n junctions; Photocatalysis; Photocatalysts; Photodegradation; Polypyrrole; Polypyrroles; Protonated-C3N4; Reduce graphene oxide; Valence band
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159750

A novel ternary PPy/P-C3N4/r-GO visible light-driven photocatalyst was fabricated via chemical polymerization of pyrrole in the presence of protonated-C3N4/reduced graphene oxide (P-C3N4/r-GO). The resulting PPy/P-C3N4/r-GO composite showed excellent photocatalytic performance under visible light for brilliant red dye (X3B) degradation and E. coli inactivation. An X3B degradation efficiency of 98% was achieved in 60 min, and an E. coli removal efficiency of 100% achieved in 90 min. Moreover, PPy/P-C3N4/r-GO displayed good recycling performance, with 90% efficiency retained over 5×3B photodegradation cycles. A plausible photocatalytic mechanism for the PPy/P-C3N4/r-GO composites was proposed, where p-n heterojunctions formed between P-C3N4 and PPy effective separate charges (photoexcited electrons accumulating in the conduction band of P-C3N4, holes accumulating in the valence band of PPy), with r-GO acting as an electron acceptor and trap. The valence band holes in P-C3N4 directly oxidize X3B, whereas conduction band electrons react with O2 to generate reactive oxygen species (superoxide and hydroxide radicals) which also degrade X3B and can inactivate E. coli. This work thus introduces an efficient metal-free ternary photocatalyst system for environmental applications. [Display omitted] •PPy/P-C3N4/r-GO composites were prepared by polymerizing pyrrole on P-C3N4/r-GO.•The composites displayed outstanding photocatalytic activity and stability under visible light.•100% degradation of brilliant red dye and inactivation of E. coli occurred in 90 min.••O2− and •OH generation underpinned the excellent performance of PPy/P-C3N4/r-GO.