FeOCl Nanoparticles Loaded onto Oxygen-Enriched Carbon Nanotubes and Nickel-Foam-Based Cathodes for the Electro-Fenton Degradation of Pollutants

Electrochemical advanced oxidation processes (EAOPs) are a class of promising technologies for wastewater remediation. The challenge of EAOPs is the in situ generation and activation of hydrogen peroxide (H2O2) to evolve reactive oxygen species (ROS) simultaneously with low energy consumption and high performances. In this work, we designed an EAOP system, coupling FeOCl nanoparticles on oxygen-enriched carbon nanotubes (O-CNTs) and a nickel foam (FeOCl/O-CNTs/NF) cathode for electro-Fenton (EF) reactions and an IrO2/Ti anode for anodic oxidation (AO) simultaneously. Specifically, the defects and oxygen functional groups on O-CNTs introduced by a modified Hummers’ method could induce the charge redistribution of O-CNTs for outstanding two-electron oxygen-reduction-reaction performances (H2O2 selectivity of 73%) and provide more anchoring sites for the loading of active cocatalyst nanoparticles. Thus, abundant FeOCl nanoparticles were successfully loaded onto O-CNTs. Such a FeOCl/O-CNTs/NF cathode exhibited a high H2O2 production rate of 95 mmol gcat–1 h–1 because of the improved exposure of catalytic active sites supported on nickel foam to attain a large specific surface area. •OH was generated from H2O2 via both heterogeneous and homogeneous EF processes induced by the FeOCl/O-CNTs/NF cathode and leached ferrous ions accordingly. Sulfamethoxazole (SMX) was completely removed within 30 min at a low specific energy consumption of 0.024 kWh g–1 SMX–1. Thus, the simultaneous FeOCl/O-CNTs/NF-based EF system and AO provide an efficient and cost-effective technology for organic contaminant remediation.