Synergistic effect of Fe and Ni on carbon aerogel for enhanced oxygen reduction and H₂O₂ activation in electro-Fenton process

A novel cathode, iron-nickel alloy modified carbon aerogel (FeNi-CA), was successfully synthesized and utilized as the cathode in an electro-Fenton process for acetaminophen degradation. The incorporation of Fe and Ni in the carbon matrix resulted in superior electrochemical characteristics and catalytic performance compared to Fe-CA and Ni-CA. The unique microstructure of FeNi-CA, including the presence of alloy nanoparticles, carbon defects, and abundant oxygen functional groups, enhanced 2e⁻ oxygen reduction activity and electrocatalytic performance. This enabled FeNi-CA to exhibit a dual functionality of H₂O₂ electro-generation and in situ activation. FeNi-CA demonstrated good performance over a wide pH range at a low current density of 4.44 mA/cm². Under optimal conditions, 99.9 % of acetaminophen was removed with a reaction rate constant (kobs) of 0.054 min⁻¹ through electro-sorption and oxidation processes. Importantly, a satisfactory degradation effect was achieved in the absence of external aeration. This work provides a potential wastewater treatment solution without the need for external aeration or additional chemical input by simultaneously achieving oxygen evolution reaction at the anode and oxygen reduction reaction at the cathode. Furthermore, FeNi-CA demonstrated good reusability performance with controlled metal leaching after five consecutive runs, suggesting its potential for sustained use in electro-Fenton processes over the long term.