Graphene oxide enhanced Iron‑carbon aerogel electrodes for heterogeneous electro-Fenton oxidation of phenol

Abstract

Enhancing the selectivity of 2e⁻ oxygen reduction reaction (ORR) to produce H₂O₂ has been a longstanding focus in the field of heterogeneous electro-Fenton (EF). This study presents the development of composite electrodes prepared by different iron sources, which feature graphene oxide (GO) enhanced single-atom iron‑carbon aerogel (SA-FeNGA/CF) electrodes and nanometer iron‑carbon aerogel (NP-FeNGA/CF) electrodes. The microstructure and composition of the cathodes were explored using SEM, TEM, XPS, FTIR, XRD and AC-HAADF-STEM. The COD of the reaction solution on SA-FeNG₁A/CF electrode can be almost completely removed within 4 h in neutral conditions with the current densities of 3 mA/cm², and the mineralization current efficiency (MCE) could reach up to 98.5 % within 1 h. The incorporation of GO significantly enhanced the graphite N content in the SA-FeNG₁A/CF composite to 51.5 %, which is instrumental in facilitating the formation of H₂O₂, but the graphite N content in the NP-FeNG₁A/CF experiences a decline. A higher concentration of 2.46 mg/L hydroxyl radicals (•OH) can be produced on the SA-FeNG₁A/CF electrode, which is capable of to the phenol degradation. This work proposes a new insight into the rational design of efficient iron‑carbon aerogel electrode for the EF system.