A sustainable and metal-free advanced oxidation process for efficient water purification by electrified reduced graphene oxide membrane

The bigger pictureApproximately a quarter of the global population is undergoing a crisis of "extreme water scarcity," and by 2025, up to 3.5 billion individuals are expected to face water shortages. This critical issue highlights the importance of providing access to clean water and sanitation, as outlined in the United Nations Sustainable Development Goal 6. Herein, we develop a sustainable and metal-free advanced oxidation process by an electrified reduced graphene oxide (rGO) membrane used as the cathode in the flow-through electrochemical membrane system, which demonstrates efficient degradation of a broader range of water contaminants and long-term stability even in various real water matrices. This study unravels the sustainable water decontamination mechanism of the electrified rGO membrane at the cathode, paving the way toward the application of cheap carbonaceous catalysts for effective and sustainable water purification and decontamination.Highlights•A sustainable and metal-free AOP process based on electrified rGO membrane is proposed•Excellent pollutant removal and long-term stability are demonstrated•Catalytic performance of membrane is explained both theoretically and experimentallySummaryThe catalyst efficiency-stability trade-off still remains the major challenge for advanced oxidation processes (AOPs). To overcome this challenge, herein, we develop a sustainable and metal-free AOP by an electrified reduced graphene oxide (rGO) membrane in the flow-through electrochemical membrane system, demonstrating efficient degradation of a broader range of water contaminants (>90%), significant reduction of the effluent toxicity (harmless effluent) via the electrochemical activation of peroxymonosulfate (PMS), and long-term stability (>50 h) even in various real water matrices. The external electric field maintains the morphology of rGO and promotes the redox cycle between C–O and C=O groups of rGO at the cathode, with the electrochemical regenerated C–O groups providing sustainable active sites for the formation of rGO-PMS∗, ensuring the long-term stability of the electrified rGO membrane. This work paves the way toward the application of cheap carbonaceous catalysts for effective and sustainable water purification and decontamination.Graphical abstract