Simultaneously accelerating the regeneration of FeII and the selectivity of 2e-oxygen reduction over sulfide iron-based carbon aerogel in electro-Fenton system

The regeneration of surface FeII and the electro-formation of H2O2 play crucial roles for determining the degradation efficiency of heterogeneous electro-Fenton process. The sulfide iron-based carbon aerogel was synthesized directly as cathode. The main composition of iron compounds were Fe3O4 and FeS center dot FeS2, which were embedded in the matrix of carbon aerogels. Most of sulfur was evenly distributed on carbon, favoring the formation of -COOH groups. The nature of existed sulfur were investigated by temperature-programmed reaction spectroscopy respectively under the CO2 and air. The S-doping promoted the regeneration of Fe-II and improved the selectivity of 2e(-) oxygen reduction with iron-based carbon materials. As high as 99 % removal of dimethyl phthalate and 3-chlorophenol were obtained in 240 min. Meanwhile, the EPR results demonstrated that HO center dot was formed by on site decomposing H2O2 with FeSCA, which exhibited high stability with low Fe leaching (< 2 ppm) and high recyclability even in acidic medium.