Fabrication of graphene@graphite-based gas diffusion electrode for improving H^sub 2^O^sub 2^ generation in Electro-Fenton process

A typical graphene@graphite-based gas diffusion electrode (G-GDE) with high conductivity and remarkable electrocatalytic activity was prepared for the electro-Fenton (E-Fenton) system in order to achieve an efficient degradation for organic pollutants. The G-GDE was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and nitrogen adsorption-desorption analysis. Continuous on-situ generation of H2O2 through an oxygen reduction reaction (ORR) was achieved at the non-metallic G-GDE cathode. Rhodamine B (RhB) was used as a model organic pollutant to evaluate the performance of the E-Fenton system with G-GDE cathode. The effects of pH, Fe2+ concentration were investigated. After 60 mm, the removal rate reached 98% with G-GDE in the optimal condition, which was higher than that with traditional graphite-based gas diffusion cathode (GDE) and graphite sheet cathode (GE), and the energy consumption with G-GDE was only 84% of that with GDE under the same condition. The calculated electron transfer number (n) of the ORR with G-GDE was 2.1-2.2 in the selected potential range using rotating disk electrode. The results demonstrated that the addition of graphene could enhance the ORR activity by virtues of improving electrochemical conductivity and porous structure. Moreover, excellent corrosion resistance and reuse ability were also presented for the G-GDE electrode. So the G-GDE can be used as a low-cost and efficient cathode material for degradation of organic wastewater in E-Fenton system.