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

Abstract

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 radical. However, the slow reduction of Fe(III) to Fe(II) of Fenton phase hinders the continuous and effective ·OH 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. 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.