Overpotential regulation of vanadium-doped chitosan carbon aerogel cathode promotes heterogeneous electro-Fenton degradation efficiency

This work aimed at exploring the effect of optimal overpotential discrepancy between two-electron oxygen reduction reaction (OP2eORR) and metal reduction reaction (OPMRR) of the cathode on electro-Fenton (EF) system performance, and proposing strategy to eliminate overpotential discrepancy. Therefore, series of vanadium-doped chitosan carbon aerogel (xCCA-V) cathodes were fabricated by controlling graphitization degree. With carbonized temperature of 900 °C, the OP2eORR of the 900CCA-V was −0.5 V vs. SCE, the same with the OP for vanadium reduction reaction (OPVRR). This identical OP of the 900CCA-V endowed excellent EF performance, with ciprofloxacin removal of 98.1%, and TOC removal significantly increased by 41.8% compared with Ferrum-doped CCA (900CCA-Fe). Density functional theory calculation revealed efficient active sites for H2O2 adsorption on the 900CCA-V surface. Degradation pathways of ciprofloxacin and intermediates toxicity were determined. This work provides inspiration for developing strategy for overpotential regulation and design novel and efficient cathodes for enhancing EF performance.