Strategies for promoting the degradation of phenol by electro-Fenton: Simultaneously promoting the generation and utilization of HO.

The use of the electro-Fenton process to continuously generate HO and efficiently degrade organic pollutants is considered a promising technology. The ratio of generation of HO is usually regarded as the critical step; however, how the HO is utilized is also of particular importance. Herein, activated carbon was activated at different temperatures and used to explore the effect of nitrogen doping on the production and utilization of HO in the electro-Fenton-based degradation of organic pollutants. The experimental results indicate that nitrogen-doped activated carbon simultaneously promotes the generation and utilization of HO, which is attributed to the regulation of the competition between phenol and O adsorption by the doped nitrogen. Nitrogen doping not only improves 2eORR selectivity but also aggregates phenol near the cathode to balance the concentrations of phenol and ·OH. Density functional theory (DFT) calculations further confirmed that pyrrole-N as a dopant promoted the adsorption of phenol, while pyridine-N was more favorable for O adsorption. The unique balance of nitrogen types possessed by modified activated carbon NAC-750 permits the efficient synergistic generation and utilization of HO in a balanced manner during the degradation of phenol. This work provides a new direction for the rational nitrogen-doping modification of activated carbon for the electro-Fenton-based degradation of organic pollutants.