Hydrogen peroxide generation from gas diffusion electrode for electrochemical degradation of organic pollutants in water: A review

At present, electrochemical advanced oxidation processes (EAOPs) have attracted extensive attention to treat refractory organic pollutants effectively because of their high efficiency and strong oxidation ability. Highly efficient hydrogen peroxide (H2O2) production through electrochemical oxygen reduction reaction (ORR) is of great significance for degrading organic pollutants. Due to the excellent gas-liquid-solid three-phase structure, gas diffusion electrodes (GDEs) present high cost-effectiveness, low energy consumption and high oxygen utilization efficiency in 2e- ORR process. Recently, GDEs as the cathode for EAOPs applications have progressively become a popular research field. Herein, an in-depth overview of multifarious GDEs currently available in EAOPs for environmental remediation was presented. In this review, the preparation, evaluation and modification methods of GDEs were summarized. Particular emphasis was placed on the applications of GDEs-based cathodes for H2O2 generation and pollutants degradation by EAOPs, mainly including the effects and current development of fabrication method, evaluation parameters and cathode modification. Moreover, to expand the practical application in electro-Fenton, photoelectro-Fenton and iron-free Fenton-like process, typical reactors designs and electrochemical processes using GDEs were further highlighted. Finally, the prospect of GDEs for H2O2 production and water treatment were proposed.