Continuous Bulk FeCuC Aerogel with Ultradispersed Metal Nanoparticles: An Efficient 3D Heterogeneous Electro-Fenton Cathode over a Wide Range of pH 3–9

Novel iron–copper–carbon (FeCuC) aerogel was fabricated through a one-step process from metal-resin precursors and then activated with CO2 and N2 in environmentally friendly way. The activated FeCuC aerogel was applied in a heterogeneous electro-Fenton (EF) process and exhibited higher mineralization efficiency than homogeneous EF technology. High total organic carbon (TOC) removal of organic pollutants with activated FeCuC aerogel was achieved at a wide range of pH values (3–9). The chemical oxygen demand (COD) of real dyeing wastewater was below China’s discharge standard after 30 min of treatment, and the specific energy consumption was low (9.2 kW·h·kg–1COD–1), corresponding to a power consumption of only ∼0.34 kW·h per ton of wastewater. The enhanced mineralization efficiency of FeCuC aerogel was mostly attributable to ultradispersed metallic Fe–Cu nanoparticles embedded in 3D carbon matrix and the CO2–N2 treatment. The CO2 activation enhanced the accessibility of the aerogel’s pores, and the secondary N2 activation enlarged the porosity and regenerated the ultradispersed zerovalent iron (Fe0) with reductive carbon. Cu0 acted as a reduction promoter for interfacial electron transfer. Moreover, activated FeCuC aerogel presented low iron leaching (<0.1 ppm) in acidic solution and can be molded into different sizes with high flexibility. Thus, this material could be used as a low-cost cathode and efficient heterogeneous EF technology for actual wastewater treatment.