Three-dimensional nickel foam electrode for efficient electro-Fenton in a novel reactor

One of the bottlenecks often encountered in electro-Fenton technology is its low ability to produce hydrogen peroxide (H₂O₂). Thus, the hunt of suitable electrodes and reactor are a must to be tackled in order to improve the efficiency of the system. In this study, three-dimensional nickel foam was selected as cathode for in situ generating H₂O₂ efficiently and graphite was the control group in an enhanced oxygen mass transfer reactor. The micro-structure and electrochemical performance of electrodes were tested by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electro-chemical impedance spectroscopy (EIS) and Tafel polarization techniques, respectively. The concentration of H₂O₂ produced by nickel foam cathode was 780.63 μmol/L and the removal efficiency of rhodamine B (RhB) was reached to 92.5% in 60 min. SEM and Tafel results showed that both nickel foam and graphite electrodes were porous structure cathodes. Moreover, CV and EIS experimental results indicated nickel foam electrode was controlled by charge transfer process while had a better transfer than graphite electrode. Electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was ·OH, accounting for RhB degradation in electro-Fenton progress. Therefore, in terms of pollutant degradation in the electro-Fenton process, nickel foam electrode together with novel reactor was a promising technique.