Natural air diffusion electrode modified with metal-organic frameworks derived Fe doped porous carbon for sulfamethazine degradation by heterogeneous electro-Fenton

A novel and efficient heterogeneous electro-Fenton process has been developed, utilizing a modified natural air diffusion electrode (NADE) as a bifunctional cathode. This cathode is based on Fe-doped porous carbon (Fe-PC(800)), which is derived from metal-organic frameworks (MOFs). This cathode has the unique ability to simultaneously generate and activate H2O2 in-situ without the need for aeration. Fe-PC(800) synthesized at a pyrolysis temperature of 800 °C exhibited the optimal catalytic efficiency for sulfamethazine (SMT) degradation over a wide pH between 3~11, attributed to the production of Fe0 and Fe3C which improved electron transfer efficiency. The presence of Fe0 facilitated the regeneration of Fe2+ and thus increased the activity of the bifunctional cathode in the Hetero-EF process. The co-action mechanism of •OH and 1O2 was confirmed by the radical quenching and electron paramagnetic resonance (EPR) investigations. NADE modified with Fe-PC(800) demonstrated broad applicability towards diverse contaminants and exceptional stability in ten consecutive cycling experiments. This study shed light on the viability of a straightforward and economically viable cathode utilizing NADE without the need of aeration in a Hetero-EF system, offering novel perspectives on bifunctional electrode design and the activation mechanism involving in-situ production and catalysis of H2O2.