Enhanced catalytic degradation by using RGO-Ce/WO3 nanosheets modified CF as electro-Fenton cathode: Influence factors, reaction mechanism and pathways

Development of an efficient cathode in advanced oxidation process is an important challenge. In this work, we synthesized a low-cost, high-catalytic-active and stable reduced graphene oxide (RGO)-Ce/WO3 nanosheets (RCW) to modify carbon felt (CF) as cathode to degrade ciprofloxacin (CIP) in electro-Fenton process. Compared to traditional heterogeneous electro-Fenton process, carbon black was substituted by RGO and poly tetra fluoroethylene was avoided to be used as binder. We found that RCW/CF cathode reached about 100% degradation efficiency of CIP after 1 h and 98.55% mineralization degree after 8 h. Meanwhile, it had a very high current density, about 2.5 times that of CF. RCW/CF cathode produced more O-center dot(2)-, H2O2 and (OH)-O-center dot via one electron reduction process (O-2 -> O-center dot(2)--> H2O2). The modified cathode kept a stable performance for high CIP degradation efficiency during 5 cycles. The introduction of RGO could promote electron transfer, and the adding of Ce into the WO3 lattice provided superior conditions for the adsorption and activation of oxygen molecules, thus promoting the formation of active oxygen species on the surface of RCW. This novel RCW/CF composite is an efficient and promising electrode for removal of CIP in the wastewater.