Carbonaceous materials applied for cathode electro-Fenton technology on the emerging contaminants degradation

Emerging contaminants (ECs) are concerned worldwide due to their ubiquitous, persistence, high toxicity and low treatment efficiency in conventional processes. Meanwhile, the electro-Fenton (EF) technique has gained significant attention owing to its high efficiency and environmental compatibility for the degradation of ECs. Nevertheless, the EF process has suffered low Faraday efficiency, high cost and poor mass transfer, mainly in the low efficiency of Fe3+/Fe2+ cycle, insufficient capacity of oxygen reduction and limitation of low pH. The ways to improve EF efficiency include adding catalysts, optimizing electrode materials, and coupling other technologies. Among them, cathode material is the key factor affecting EF efficiency. In recent years, researchers have carried out a large number of related studies, among which carbonaceous materials (CMs) have become one of the most promising EF cathode materials due to their excellent performance advantages. Many works on the preparation and modification of novel carbon materials have been paid attention to, but lacks a systematic review report summarizing carbon cathode in EF process. Aiming at this issue, this paper summarizes the modification of CMs to improve H2O2 electrogeneration, strengthen Fe3+/Fe2+ cycle efficiency, and broaden pH window, respectively. Besides, the development of biochar materials is summarized, and the existing shortcomings and future development directions in the field of cathode EF are briefly discussed.