▎ 摘　　要

This paper reports for the first time the performance of pristine graphene - in the form of graphene monolayer (G(mono)), graphene multilayer (G(multi)) and graphene foam (G(foam)) - as cathode material in an electrochemical advanced oxidation process known as electro-Fenton (EF) for wastewater treatment. This study led to three major findings: (i) the electrogeneration of H2O2 was proven feasible with the three graphene materials at an optimal cathodic potential (E-cat) (-0.6 V vs Ag/AgC1) comparable to that obtained with other carbon-based cathodes such as graphite and carbon felt (C-felt); (ii) for all forms of graphene, the Fe2+ regeneration rate and the H2O2 production yield were sufficient to sustain the formation of (OH)-O-center dot through the Fenton reaction, leading to the degradation and mineralization of phenol, used as a model pollutant and; (iii) over the 3 graphene materials, Gfoam exhibited the highest H2O2 electrogeneration yield (4.25 mg-H2O2 L-1 cm(-3)), degradation rate (0.0081 min(-1)) and yield (78% after 3 h), mineralization rate (0.0818 h(-1)) and yield (50% after 8 h). The superiority of G(foam) was attributed to its high purity (1(2D)/I(G) = 1.58, C1s/O1s = 22), low interfacial charge-transfer resistance (R-ct) (1.6 Omega), high electroactive surface area (55.017 cm(2)) and three-dimensional (3D) porous structure (100-600 mu m pore diameter), allowing it to outcompete conventional 3D carbon-based cathode materials in terms of efficiency and energy requirements. These results open up the possibility to use pristine graphene in EF for the treatment of wastewater. (C) 2016 Elsevier Ltd. All rights reserved.