FeOOH-Catalyzed Heterogeneous Electro-Fenton System upon Anthraquinone@Graphene Nanohybrid Cathode in a Divided Electrolytic Cell: Catholyte-Regulated Catalytic Oxidation Performance and Mechanism

Abstract

The aim of the present work was to illuminate the catholyte-regulated$\$ncatalytic oxidation performance and mechanism of the FeOOH-catalyzed$\$nheterogeneous electro-Fenton (Hetero-EF) system operating in a divided$\$nelectrolytic cell. Depending on pH evolution with electrolysis time, the$\$neffect of the catholyte type on the H2O2 yield and current efficiency$\$nwas investigated on an anthraquinone@electrochemically reduced grapheme$\$noxide nanohybrid cathode. Based on the physicochemical characterization$\$nof the supported FeOOH nanoparticles, it was found that the Hetero-EF$\$nsystem exhibits the synchronous role of coupled adsorption and$\$nelectrocatalytic oxidation for rhodamine B (RhB) degradation, with a$\$nhigher apparent rate constant in MgSO4 catholyte and a higher$\$nmineralization rate in Na2SO4 catholyte. The catholyte-regulated$\$ncatalytic oxidation mechanism was proposed according to radical$\$nscavenging experiments. In MgSO4 catholyte, the Hetero-EF process$\$nfollows a classic Haber-Weiss mechanism mediated by the dissolved iron$\$nions and surface iron species to generate center dot OH, while in Na2SO4$\$ncatholyte, the catalytic decomposition of H2O2 by surface iron species$\$nand the deactivation of Fe-III-OH center dot H2O2 complex to form HO2$\$ncenter dot(O-2(center dot-)), center dot OH and ferryl species ( Fe-IV =$\$nO). X-ray photoelectron spectroscopy and electrochemical impedance$\$nspectroscopy measurements revealed the desirable stability of Hetero-EF$\$nsystem after multiple reutilizations. (C) The Author(s) 2015. Published$\$nby ECS. All rights reserved.