Improved electrocatalytic performance of Fe/CeO2 bifunctional electrocatalyst by simultaneous H2O2 in-situ generation and activation

Heterogeneous Electron-Fenton (HEF) has been recognized as a prospective solution in tackling refractory organic contaminants. Nevertheless, the low production efficiency of H2O2 and external addition of H2O2 or Fe2+ limit its wide application. In this work, the bi-functional Fe/CeO2 composites were designed to achieve the simultaneous generation of H2O2 and center dot OH. The electro-catalysis experiments indicate Fe/CeO2 composites present 97% degradation efficiency for 17 mg/L phenol within 0.5 h and it still presented good degradation performance in high salinity condition. The H2O2 yield produced by Fe, CeO2, and Fe/CeO2 revealed that CeO2 and Fe/CeO2 have similar H2O2 productivity about 24 mg/L h-1, suggesting that H2O2 is mainly produced by CeO2. O2-TPD profiles, XPS and Raman spectra indicate that the relative amount of oxygen deficient region (Ov) and chemisorbed oxygen in Fe/CeO2 composites is higher than that in CeO2, which promote the adsorption of O2. Then the effective O2 adsorption can ensure the subsequent electrocatalysis of O2 to H2O2. The impedance measurement shows that Fe/CeO2 composite exhibits excellent conductivity, enabling the transporting of electron. EPR experiments and radical scavenging experiments disclosed that the primary reactive species was center dot OH, proving the in-situ activation of H2O2 to center dot OH by Fe/CeO2 composites. This work should offer new insights about the rational design of bi-functional catalyst towards simultaneous generation and activation H2O2 to center dot OH, thus improving electrocatalytic performance.