Air-driven carbon diffusion electrodes for in situ H2O2 generation and water remediation

Abstract

This study optimized and applied a carbon cloth-supported gas diffusion electrode (GDE) for the efficient electrogeneration of hydrogen peroxide (H2O2) in acidic media using oxygen reduction reaction (ORR). The optimized conditions applied included a catalytic layer loading of 15 mg cm-2 and 20%wt poly(tetrafluoroethylene) (PTFE), which resulted in the production of 1,406 mg L− 1H2O2 at 50 mA cm-2, with a current efficiency of 33.2% and energy consumption of 163.8 kJ kg-1. Atmospheric air proved to be an effective sustainable O2(g) source, as its application yielded 1,044 mg L-1 of H2O2, with a 9% current efficiency reduction compared to ultrapure O2(g). The electrochemical system was successfully applied for the effective degradation of sulfamethoxazole (SFX) via Electro-Fenton (EF) and Photo-Electro-Fenton (PEF) processes, where complete SFX removal was achieved within 20 and 15 min of electrolysis, respectively. The PEF process exhibited higher mineralization (55.9%) compared to EF (22.1%), and this was primarily attributed to UVA-enhanced Fe2+ regeneration. The results of this study highlighted the potential of the optimized GDE for application toward sustainable in situ H2O2 production and emerging pollutant treatment using atmospheric air as a precursor source of O2(g).