Atomic Fe‒P Pairs Eliminate H₂O₂ Migration Barriers for Sustainable Electro-Fenton Water Treatment

The electro-Fenton process, involving O₂ reduction to H₂O₂ and its subsequent activation into •OH, is an eco-friendly strategy for degrading organic pollutants in wastewater. Enhancing electro-Fenton efficiency necessitates two distinct functional sites: one for H₂O₂ generation to preserve the O‒O bond and the other for activation to cleave the O‒O bond. Despite extensive efforts to optimize these functions, the role of H₂O₂ migration between sites has been largely overlooked. Excessive inter-site distances can lead to sluggish H₂O₂ migration, making it a potential rate-limiting step in electro-Fenton catalysis. To address this challenge, we have developed Fe‒P pairs at the atomic level, achieving the theoretical shortest site distance, with single-atom Fe acting as the H₂O₂ activation center and P in its first coordination shell facilitating H₂O₂ generation. Experimental and theoretical analyses revealed that Fe‒P pairs significantly shortened the H₂O₂ diffusion time to ∼1.5 ps, over 10 times faster than unpaired configurations, by reducing the migration distance, thereby improving the H₂O₂ utilization efficiency by over 4 times and enhancing electro-Fenton performance. Life cycle assessment further highlighted the low environmental impact of this approach, indicating its potential for large-scale wastewater treatment. By exploiting the previously neglected role of H₂O₂ migration, this study not only enhances our understanding of the electro-Fenton process but also offers new insights into the rational design of advanced electro-Fenton catalysts.