Selective catalytic two-electron O2 reduction for onsite efficient oxidation reaction in heterogeneous electro-Fenton process

The selective two-electron oxygen reduction reaction (ORR) for an onsite Fenton oxidation reaction over an integrated cathode is a promising method for environmental restoration. Here, an economic iron-copper-embedded carbon aerogel (FeCuC) exhibited high ORR activity (half-wave potential of −0.19   V vs SCE). The electron transfer number (n) over FeCuC was 2.9. Indeed, Fe@Fe 3 C promoted the ORR activity, while Cu enhanced the selectivity of the two-electron ORR. Meanwhile, the simultaneous incorporation of Fe and Cu simultaneously facilitated the sequential Fenton oxidation induced by H 2 O 2 . The individual rate constants for ORR and the oxidation reaction successfully revealed the fact that the efficient Fenton oxidation reaction again promotes again the 2-electron O 2 reduction pathway. The application of FeCuC as a cathode in the electro-Fenton (EF) process, involving both high ORR and high Fenton oxidation activities, exhibited efficient total organic carbon (TOC) removal (88–99%) in 240   min for dimethyl phthalate (DMP), imidacloprid (IMI), bisphenol A (BPA) and perfluorooctanoate (PFOA). Moreover, five types of sanitary sewage were successively treated to meet the national discharge standards (chemical oxygen demand (COD)   <   50   mg   L −1 ) with relatively low specific energy consumption (20–40   kW·h·(kg COD ) −1 ) using FeCuC in the heterogeneous EF process.