N-doped graphene aerogel cathode with internal aeration for enhanced degradation of p -nitrophenol by electro-Fenton process

A columnar N-doped graphene aerogel (NGA) was successfully fabricated by one-step hydrothermal synthesis using L -hydroxyproline as reductant, N-doping, and swelling agent, and it was used as the cathode with internal aeration mode for the electro-Fenton degradation of p -nitrophenol. Owing to the stable solid–liquid–gas three-phase interface, more active defects, and modulated nitrogen dopants, the NGA cathode exhibited enhanced electrocatalytic activity. H 2 O 2 could be continuously electro-generated via a two-electron oxygen reduction, and the yield of H 2 O 2 was 153.3 mg·L −1 ·h −1 with the low electric energy consumption of 15.3 kWh kg −1 . Simultaneously, the NGA cathode had better charge transfer capability with N-doping, which was conducive to the conversion of Fe 3+ /Fe 2+ . Under the optimal condition, nearly 100% removal of p -nitrophenol and 84% removal of TOC were obtained within 60 and 120 min, respectively. The NGA cathode also presented good stability and versatile applicability in different water matrices. Therefore, the NGA is a cost-effective cathode material in electro-Fenton system with adequate activity and reuse stabilization.