High-efficiency electro-Fenton process based on in-situ grown CoFeCe-LDH@CFs free-standing cathodes: Correlation of cerium and oxygen vacancies with H2O2

Electro-Fenton is one of the promising clean and renewable technologies for refractory pollutants control. Herein, a ternary metal-layered double hydroxide (CoFeCe-LDH) nanoparticle in situ growth on carbon felt (CF) was prepared to fabricate heterogeneous electro-Fenton (HEF) cathode via one-pot hydrothermal strategy. The optimal CoFeCe-LDH@CF cathode demonstrated high oxygen reduction activity, low resistance and efficient degradation of DOX over a wide pH range (pH = 1–9). On one hand, the introduction of Ce resulted in the generation of plenty of oxygen vacancies (Oα) on the electrode surface. On the other hand, the coexistence of Co2+/Co3+, Fe2+/Fe3+ and Ce3+/Ce4+ redox pairs significantly enhanced interfacial electron transfer and promoted the generation and decomposition of in situ H2O2, which in turn boosted the production of reactive radicals (OH, O2− and 1O2). The Estimation Program Interface (EPI) certificated that intermediates resulted from DOX degradation in the system were relatively low in toxicity to typical aquatic organisms. Meanwhile, the effect experiments of various ions, types of wastewater and pollutants were carried out in the CoFeCe-LDH@CFs-HEF system and all showed excellent pollutant degradation, proving that the developed cathode had special applicability and reusability. Thus, this paper gave a global contribution to develop the high-performance cathode by exploring the synergistic effects of trimetals in LDH and proposed a reliable strategy for enhanced degradation of contaminant by HEF system.