A Complex-Sequestered Strategy to Fabricate Fe Single-atom Catalyst for Efficient Oxygen Reduction in a Broad pH-range

Abstract A facile complex-sequestered strategy has been proposed to fabricate a cost-effective oxygen reduction reaction (ORR) catalyst with Fe single-atom dispersed on nitrogen-doped porous carbon (Fe SA/NPCs). The key step for such an approach is the pyrolysis of an iron-agar complex, in which the “complex-sequestration” effect between hydrated iron(III) and agarose functions to prevent the agglomeration of single Fe atoms. the Fe SA/NPCs catalyst exhibits excellent ORR activities with half-wave potentials comparable to those of commercial Pt/C in media of a broad pH-range, which are superior to those of most reported non-precious-metal ORR electrocatalysts. Moreover, the Fe SA/NPCs catalyst has also demonstrated outstanding durability and methanol tolerance. Density functional theory calculations reveal that the improved electron transfer from single Fe atom onto adsorbed *OH species in the rate-determining step could be the major reason for the exceptional ORR performance of Fe SA/NPCs in both acidic and alkaline media.