Atomic-level modulation of local coordination environment at Fe single-atom sites for enhanced oxygen reduction

Single-atom catalysts (SACs) have aroused extensive attention due to their ultrahigh activity and selectivity. However, precisely regulating and designing the coordination microenvironment of SACs to optimize the catalytic efficiency remains a great challenge. Here, a facile ionic liquid (IL) modification strategy is creatively proposed to obtain N and P dual-coordinated Fe single atoms with N unsaturated coordination on pre-designed Fe-SAC-N-4/C sites. The using a hydrophobic IL can alter the binding affinity of O-2, maintain a higher O-2 concentration at the catalyst interface, and protect Fe single atom sites from surface oxidation and methanol toxicity. Theoretical calculation indicates that this unique coordination and the N vacancy can tailor the electronic structure of the metal atoms and alter the charge distribution at the coordination structures, thus improving the oxygen reduction reaction performance. This study offers an effective approach for accurately controlling the coordination electronic structure and interface environment of SACs at room temperature.