Electro-fenton degradation of rhodamine B based on a composite cathode of Cu2O nanocubes and carbon nanotubes

In this study, rhodamine B (RhB) in aqueous solution was effectively degraded by an electro-Fenton (E-Fenton) system with a novel oxygen-fed gas diffusion electrode. This electrode was prepared by combining Cu2O nanocubes and multiwall carbon nanotubes with poly tetrafluoroethylene (Cu2O/CNTs/PTFE). The resulting Cu2O nanocubes and Cu2O/CNTs/PTFE composite cathode were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The degradation of RhB in this E-Fenton system reached 80.2% and 89.3% in 120 min at neutral pH and pH 3, respectively. A pseudofirst-order kinetics was observed for the degradation of RhB in this E-Fenton system. We studied the factors affecting the degradation of RhB with Cu2O/CNTs/PTFE composite cathodes in detail, and detected hydrogen peroxide electro-generated through the reduction Of O-2 adsorbed on the cathode and copper ions produced by the slow leakage Of Cu2O nanocubes. Cyclic voltammetry (CV) experiments revealed that a two-electron reversible redox reaction happened on the Cu2O/ CNTs/PTFE cathode in this new E-Fenton system. More importantly, we found the Cu2O/CNTs/PTFE cathode was very stable and could be reused without catalytic activity decrease, suggesting its potential in the wastewater treatment.