Recent advances in two-electron oxygen reduction catalysts for electro-Fenton technology

Abstract

The oxygen reduction reaction (ORR) holds significant potential for various energy conversion and utilization technologies. In particular, the two-electron (2e⁻) ORR process for the electro-synthesis of hydrogen peroxide (H₂O₂) facilitates the continuous production of this compound. Recently, the application of 2e⁻ ORR in electro-Fenton (EF) technology has garnered substantial attention within the wastewater treatment sector. Despite substantial advancements, challenges remain regarding the activity and stability of oxygen reduction catalysts, as well as the specific reaction conditions, which continue to limit the degradation efficiency of EF technology. Therefore, it is essential to examine the progress in research on 2e⁻ oxygen reduction catalysts and the optimization of EF reaction conditions. This review begins by summarizing the fundamental principles of ORR and EF technologies. It discusses the regulatory strategies for carbon-based and transition metal-based catalysts aimed at improving the yield and selectivity of H₂O₂. Additionally, the optimization methods for EF reaction conditions are outlined, focusing on promoting the regeneration of Fe²⁺ and broadening the operational pH range. The review further elaborates on novel coupling technologies. Finally, it envisions future research prospects to enhance the practicality and feasibility of EF technology in wastewater treatment.