Photocatalytic H2O-to-H2O2 synchronized oxidation of an organic pollutant by carbon dot/g-C3N4 composites. (20th December 2022)

• Record Type: Journal Article
• Authors: Hsu, Je-Wei; Wei, Ling-Wei; Chen, Chiaying; Wang, H. Paul
• Is Part Of: Journal of cleaner production. Volume 380:Part 2(2022)
• Publication Date: 2022-12-20
• Subjects: Photocatalysis -- Graphitic carbon nitride -- Carbon dots -- Advance oxidation processes -- Hydrogen peroxide; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2022.134918
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Photocatalytic oxidation of organic pollutants using the solar energy is environmentally and economically attractive for developing an energy sustainable organic wastewater treatment process. Here, we employed the impregnation-thermal method to prepare novel carbon dot (CD) dispersed graphitic carbon nitride (g-C3 N4 ) (GCN)/pyromellitic dianhydride (PDI) (CD/GCN/PDI) composites for photocatalytic H2 O-to-H2 O2 and on-site oxidation of organic pollutants in contaminated or waste water. After a 5-h visible-light irradiation, 252 μM of H2 O2 can be yielded by the CD/GCN/PDI composites. The CD, serving as an electron reservoir, dispersed on the GCN/PDI composite (i.e., CD0.003 /GCN/PDI) facilitates the separation of photo-excited electrons to promote the two-electron reduction O2 -to-H2 O2 (O2 →˙O2 − →H2 O2 ). Most importantly, it also on-site activates H2 O2 to form ·OH radicals (H2 O2 →·OH) to enhance oxidation of organic pollutants (e.g., methylene blue and bisphenol A). The ·OH, ∙O2 −, and photogenerated h + account for 4–5%, 14–18%, and 20–25% oxidation of organic pollutants under visible-light irradiation for 3 h, respectively. The CD0.003 /GCN/PDI composite was also tested for photocatalytic oxidation of the organic pollutant under visible-light irradiation for at least 12 h to demonstrate its photostability and reusability. This visible-light photocatalytic H2 O-to-H2 O2 for the enhanced oxidation of organic pollutants by the low-cost and metal-free CD/GCN/PDI composites using solar energy was developed to demonstrate the feasibility of an energy self-sufficient organic wastewater treatment process. Graphical abstract: Photocatalytic H2 O-to-H2 O2 synchronized oxidation of an organic pollutant (R) by the CD/GCN/PDI composites. The CD, serving as an electron reservoir, dispersed on the GCN/PDI composite (i.e., CD0.003 /GCN/PDI) facilitates the separation of photo-excited electrons to increase the two-electron reduction O2 -to-H2 O2 (O2 →˙O2 − →H2 O2 ). Most importantly, it also on-site activates H2 O2 to form ·OH radicals (H2 O2 →·OH) to enhance oxidation of organic pollutants (e.g., methylene blue and bisphenol A). Other on-site activated highly reactive species such as ∙O2 − and photogenerated h + also contribute to oxidation of organic pollutants in wastewater. Image 1 Highlights: The novel CD/GCN/PDI can retard charge recombination for a high yield of H2 O2 . The CD/GCN/PDI can induce highly reactive species to enhance organic pollutant oxidation. The solar-driven H2 O-to-H2 O2 by CD/GCN/PDI shows energy self-sufficient water clean-up.