A three-dimensional gas diffusion electrode without external aeration for producing H2O2 and eliminating amoxicillin using electro-Fenton process

A novel gas diffusion electrode (GDE) device is proposed that can generate hydrogen peroxide (H2O2) efficiently and consume less energy than conventional GDE devices. By optimizing the mass fraction of PTFE (40%) and CB loading (0.4 mL cm−2), the three-dimensional nickel foam composite electrode (CB/PTFE/NF) was endowed with a stable solid-liquid-gas three-phase interface. CB/PTFE/NF was used as the cathode to efficiently generate H2O2 without external aeration using the natural air flow and evolution of oxygen at the mixed metal oxide (MMO) anode as the oxygen sources. After running for 150 min under optimal conditions, the H2O2 accumulation was 398 mg L−1, the yield of H2O2 reached 3.17 mg h−1 cm−2, and the current efficiency and energy consumption were 70% and 9.7 kWh kg−1, respectively. The electrode had a good stability, and the H2O2 production could still reach 385 mg L−1 after 10 cycles. Based upon the proposed GDE device, the electro-Fenton degradation of amoxicillin (AMX) was investigated. When the Fe2+ concentration was 0.3 mM and the initial concentration of AMX was 50 mg L−1, the removal efficiency was 100% after 30 min. The active species that played a major role in the degradation of AMX was the hydroxyl radical. [Display omitted] •A novel type of floating air diffusion electrode device was designed.•The oxygen source came from the air flow and the evolution of oxygen at the anode.•The 3D structure of nickel foam was conducive to the generation of H2O2.•Hydroxyl radicals were the main active species involved in the removal of AMX.•The floating CB/PTFE/NF showed superior stability after 10 cycles.