Efficient and stable heterogeneous electro-Fenton system using iron oxides embedded in Cu, N co-doped hollow porous carbon as functional electrocatalyst

Heterogeneous electro-Fenton reaction, constituted by Fenton chemistry and electrochemical synthesis of H2O2, exhibits the powerful ability for wastewater treatment by virtue of the continuous production of strong oxidizing (OH)-O-center dot radical. However, the slow reduction of Fe(III) to Fe(II) of Fenton phase hinders the continuous and effective (OH)-O-center dot generation. Strengthening the interfacial electron transfer from conductive carbon support to Fenton phase is a feasible strategy to promote Fe(II) regeneration, which can be achieved by chemical modifications of the carbon support with N and Cu doping. In this study, we constructed a functional electrocatalyst constituted by Cu, N co-doped hollow porous carbon with embedded iron oxide nanoparticles (FeOx/CuNxHPC) by carbonizing Cu doped iron metal-organic frameworks NH2-MIL-88B(Fe). The electro-Fenton system of FeOx/CuNxHPC exhibited almost 100% removal efficiency of phenol (50 ppm) within 90 min at the pH of 4, 6, 8 and 10 at a potential of - 0.6 V vs SCE. Particularly, at pH 6, the phenol mineralization efficiency reached 81.6% within 180 min. Moreover, FeOx/CuNxHPC exhibited outstanding stability and reusability after consecutive ten tests of electron-Fenton reactions. Such enhanced electro-Fenton performance of FeOx/CuNxHPC could be ascribed to the facilitated surface Fe(II) regeneration, which greatly promoted in-situ decomposition of H2O2 into (OH)-O-center dot. By virtue of the excellent electro-Fenton performance and the facile preparation, this kind of iron-based metal-organic frameworks derived functional catalysts was proposed as the suitable cathodic material for the efficient and stable heterogeneous electro-Fenton catalysis.