Tailoring single-atom FeN4 moieties as a robust heterogeneous catalyst for high-performance electro-Fenton treatment of organic pollutants.

An iron single-atom catalyst, composed of robust FeN 4 moieties anchored on a nitrogen-doped porous carbon matrix (Fe-SAC/NC), has been developed via a surfactant-coordinated metal-organic framework (MOF) approach for application in heterogeneous electro-Fenton (HEF) process. The cohesive interaction between the surfactant and MOF precursor enabled the formation of abundant and stable FeN 4 moieties. The Fe-SAC/NC-catalyzed HEF allowed the complete degradation of 2,4-dichlorophenol with low iron leaching (1.2 mg L-1), being superior to nanoparticle catalyst synthesized without surfactant. The experiments and density functional theory (DFT) calculations demonstrated the dominant role of single-atom FeN 4 sites to activate the electrogenerated H 2 O 2 yielding •OH. The dense FeN 4 moieties allowed harnessing the modulated electronic structure of the SAC to facilitate the electron transfer, whereas the adjacent pyrrolic N enhanced the adsorption of target organic pollutants. Moreover, the excellent catalysis, recyclability and viability of the Fe-SAC/NC were verified by successfully treating several organic pollutants even in urban wastewater. [Display omitted] • Synthesis of FeN 4 moieties on N-doped carbon for effective electro-Fenton treatment. • Simultaneous increase of activity and stability of catalysts by single-atom strategy. • Superiority of SAC over nanoparticle catalyst for degradation of organic pollutants. • H 2 O 2 activation mechanism validated through DFT analysis. • High recyclability of SAC and remarkable performance in urban wastewater matrix. [ABSTRACT FROM AUTHOR]