Efficient Fe/CuFeO 2 /rGO nanocomposite catalyst for electro‐Fenton degradation of organic pollutant: Preparation, characterization and optimization

Facile synthesis of chitosan-derived maillard reaction productions coated CuFeO2 with abundant oxygen vacancies for higher Fenton-like catalytic performance

The two shortcomings of the Fenton-like catalyst delafossite-type oxide (CuFeO₂) lie in its spontaneous agglomeration and deactivation under neutral working pH. To remedy these drawbacks, novel Fenton-like catalyst chitosan-derived maillard reaction productions coated CuFeO₂ with abundant oxygen vacancies (OV-CuFeO₂@MRPs) was synthesized by hydrothermal method with no extra chemical reducing agent. The systemic characterization illustrated that richer oxygen vacancies and higher particles dispersion of OV-CuFeO₂@MRPs contributed to better Rhodamine B (RhB) degradation under neutral pH compared to pure CuFeO₂. Cooper antisite defects in OV-CuFeO₂@MRPs were evidenced by X-ray powder diffraction (XRD), fourier transform infrared spectrometer (FTIR), Raman spectra and energy dispersive X-ray spectrometer (EDX) linescan. To keep the charge balance, OV-CuFeO₂@MRPs should form rich oxygen vacancies, which was confirmed by X-ray photoelectron spectroscopy (XPS) and solid-state electron paramagnetic resonance spectrometer (solid-state EPR). Furthermore, the electrochemical impedance spectroscopy (EIS) analysis revealed that oxygen vacancies could improve the electron transfer. Scavenging experiments and electron spin resonance spectroscopy (ESR) analysis demonstrated that OH was main active radical during Fenton-like reaction, and the density functional theory (DFT) calculation verified that the oxygen vacancy could effectively adsorb H₂O₂ and elongate O-O bond of H₂O₂, thus promoting the activation of H₂O₂ into OH.

Graphene-Modified Composites and Electrodes and Their Potential Applications in the Electro-Fenton Process

In recent years, graphene-based materials have been identified as an emerging and promising new material in electro-Fenton, with the potential to form highly efficient metal-free catalysts that can be employed in the removal of contaminants from water, conserving precious water resources. In this review, the recent applications of graphene-based materials in electro-Fenton are described and discussed. Initially, homogenous and heterogenous electro-Fenton methods are briefly introduced, highlighting the importance of the generation of H2O2 from the two-electron reduction of dissolved oxygen and its catalysed decomposition to produce reactive and oxidising hydroxy radicals. Next, the promising applications of graphene-based electrodes in promoting this two-electron oxygen reduction reaction are considered and this is followed by an account of the various graphene-based materials that have been used successfully to give highly efficient graphene-based cathodes in electro-Fenton. In particular, graphene-based composites that have been combined with other carbonaceous materials, doped with nitrogen, formed as highly porous aerogels, three-dimensional materials and porous gas diffusion electrodes, used as supports for iron oxides and functionalised with ferrocene and employed in the more effective heterogeneous electro-Fenton, are all reviewed. It is perfectly clear that graphene-based materials have the potential to degrade and mineralise dyes, pharmaceutical compounds, antibiotics, phenolic compounds and show tremendous potential in electro-Fenton and other advanced oxidation processes.