Cu-coupled Fe/Fe3C covered with thin carbon as stable win-win catalysts to boost electro-Fenton reaction for brewing leachate treatment

The electro-Fenton oxidation is one of the powerful approaches for achieving the complete mineralization of organic pollutants in water. The key dilemma for efficient industrial application of electro-Fenton oxidation is the complicated post-processing of iron sludge, and the cost and risk associated with H2O2 transportation and storage. Herein, Cu-coupled Fe/Fe3C covered with carbon layer on carbon felt (Cu-Fe/Fe3C@C), engineered by a hydrothermal reaction followed by the consequent thermal-treatment in N2 atmosphere, as a self-supported integrated cathode were used for an onsite oxygen reduction reaction and a Fenton oxidation reaction. Experimental evidences demonstrate that, at the operating potential of -1.1 V, Fe3C can selectively catalyze O2 into H2O2 by 2e reduction pathways with assistance of metal Cu. Meanwhile, metal Fe and Cu incorporated into Cu-Fe/Fe3C@C simultaneously motivate the onsite Fenton oxidation arose by H2O2. Such a win-win catalyst presented high activity in the electro-Fenton process. In acidic environment, the efficient mineralization rate of methylene blue, nitrobenzene, phenol, and bisphenol A can reach more than 70% in 60 min, as well as the excellent stability and durability due to the protection of graphited carbon layer. Compared with tradition electrochemical degrade system, the prepared Cu-Fe/Fe3C@C electrode as cathode for practical refractory brewing leachate treatment reveal more efficient decolorization and mineralization, saving 14.3% of electricity.