Abstract
This study developed an innovative reduction-oxidation coupling process for treatment of refractory organic wastewater. We constructed a series of N5-coordinated transition metals (TMs) (TMs = Mn, Fe, Co, Ni, Cu) single-atom sites supported on nitrogen-rich carbon nitride (SA-TM-C3N5) for electrochemical generation of the surface-adsorbed hydrogen atom (H*) and hydroxyl radical (•OH). The SA-Co-C3N5 exhibited the highest activity for production of the H*-•OH redox pair, which effectively degraded refractory nitro-organic micropollutants via the parallel reduction-oxidation pathways. The SA-Co-C3N5-mediated electro-Fenton-like system showed high removal efficiency (99 %) and mineralization capacity (78 %) toward metronidazole (MNZ) with low energy consumption (0.019 kWh (g TOC)–1). The trifunctional properties of the H* have contributed to the reduction of nitro compounds, the 2e– ORR for H2O2 production and the Fenton-like catalysis for •OH generation. This work sheds lights on the development of advanced reduction-oxidation coupling process for green and sustainable water purification.
Published Version
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