Tailoring nitrogen coordination in iron- and nitrogen-co-doped carbon enhances hydrogen radical generation for the efficient hydrodefluorination of fluorinated pollutants

Hydrodefluorination is a selective and gentle approach for the safe treatment of fluorinated pollutants; however, the efficient production of hydrogen-radical (H·) active species remains a major challenge, particularly under alkaline conditions. Herein, we synthesized two iron- and nitrogen-co-doped carbon (FeNC) catalysts, FeNC-pyridine N and FeNC-pyrrole N, which have different N coordination structures. Through theoretical prediction and experimental verification, we elucidated the regulatory and improving effects of the electronic structure, through N configuration, to enhance H· generation. Particularly, FeNC-pyridine N exhibited increased electron localization, a higher electron density, a lower work function, and stronger proton affinity, which significantly enhanced H + adsorption and its subsequent reduction to H·, thereby accelerating the hydrodefluorination process. This reaction not only facilitates pollutant oxidation but also prevents the formation of highly toxic, short-chain fluorinated byproducts. We reveal the critical role of N coordination in FeNC catalysts in promoting hydrodefluorination and the oxidative removal of fluorinated pollutants, offering new insights into the safe remediation of these pollutants.