Graphitic carbon nitride embedded with graphene materials towards photocatalysis of bisphenol A: The role of graphene and mediation of superoxide and singlet oxygen. (September 2021)

• Record Type: Journal Article
• Authors: Chen, Yu-Hsin; Wang, Bo-Kai; Hou, Wen-Che
• Is Part Of: Chemosphere. Volume 278(2021)
• Publication Date: 2021-09
• Subjects: Photocatalysis -- Solar energy -- Water treatment -- Reactive oxygen species; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.130334
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Composite photocatalysts comprising graphitic carbon nitride (g-C3 N4 ) and graphene materials were synthesized and evaluated in the photocatalysis of bisphenol A (BPA) with a focus on elucidating the reaction mechanism. Embedding reduced graphene oxide (rGO) to g-C3 N4 significantly accelerated the photocatalysis rate of BPA by three folds under visible light irradiation at neutral pH. We showed that rGO synthesized in intimate contact with g-C3 N4 increased the surface areas and electrical conductivity of the g-C3 N4 composites and promoted the electron-hole pair separation. The BPA photodegradation mechanism involved selective oxidants as superoxide (O2 − ) and singlet oxygen ( 1 O2 ) that were formed through one-electron reduction of O2 and the unique oxidation of O2 − by photogenerated hole (h + ), respectively. The synthesized photocatalyst exhibited superior visible light photoreactivity to that of N-doped P25 TiO2, good photo-stability and reuse potential, and was operative in complex wastewater. rGO embedded g-C3 N4 achieved good photomineralization of BPA at 80% in 4 h compared to 40% of bare g-C3 N4 . This study sheds light on the photocatalysis mechanism of BPA with a metal-free, promising rGO/g-C3 N4 photocatalyst. Graphical abstract: g-C3 N4 embedded with reduced graphene oxide facilitates electron-hole separation and photogeneration of superoxide and singlet oxygen towards mineralization of BPA. Image 1 Highlights: rGO enhanced the photoreactivity of pure g-C3 N4 by promoting electrical conductivity and electron-hole separation. The mechanism involved O2 . − and 1 O2 that was formed through the oxidation of O2 − by h + . rGO/g-C3 N4 exhibited superior photoreactivity to that of visible light N-doped TiO2 . rGO/g-C3 N4 achieved 80% of BPA photomineralization at neutral pH compared to 40% of pure g-C3 N4 .