Efficient decontamination and detoxification of phenols by photocatalytic CQDs@Ag3PO4: Re-insights into the targeted reduction and coupling processes of ·O2– and 1O2

Abstract

Understanding of 1O2 and ·O2– is still mostly restricted to the oxidation properties for open-ring degradation of pollutants. Here we treated the P-nitrophenol (PNP) with toxic and antioxidant nitro group as the targeted pollutant with the prepared carbon quantum dots-modified silver phosphate (CQDs@Ag3PO4) photocatalyst. Quenching experiments, electron paramagnetic resonance spectroscopy characterizations, probe experiments, and comparative tests on TOC removal have confirmed photoinduced holes (h+), singlet oxygen (1O2) and superoxide anion (·O2–) induced by photogenerated electrons and molecular oxygen are the primary reactive species involved in the aerobic system. Through targeted experiments in the Xanthine/XOD and NaClO/H2O2 systems HPLC-MS and Fukui Function, it reveals the targeted reduction of ·O2– and coupling role of 1O2 and their synergistic effect on decontamination and detoxification of PNP. Moreover, the replacement of ring-opening degradation with oligomerization by 1O2 induced follows a new carbon transfer pathway. Accordingly, four PNP elimination pathways were proposed, and the key intermediates had low toxicity predicted by T.E.S.T. software, including the oligomers via coupling reaction. Conclusively, this work provides a comprehensive view of 1O2 and ·O2– and proposes an efficient strategy for realizing pollutant control by manipulating reactive species with solar energy utilization.