Using CrN4 moiety to weaken the dissociation barrier of hydroxyl on adjacent single iron atom for efficient oxygen reduction

• ORR activity depends on orbital level before being further evaluated by bond order. • Cr=N 2 =Fe ABCs is developed using a time-/energy-saving Joule heating strategy (∼ 10 s). • Higher ORR activity than commercial Pt/C and stable operation of ZAB for over 300 h. The strong perturbation of the valence band within the entire material system and accelerated *OH dissociation from Fe site are triggered by incorporating CrN 4 moiety with low Fenton effect and *OH adsorption energy. This atomically dispersed Cr=N 2 =Fe electrocatalyst is developed by adopting a super time-/energy-saving Joule heating strategy (∼ 10 s). Through the investigation of valence orbital energy levels and valence electron behavior for the prepared catalysts, in combination with in-situ Raman testing and theoretical calculations, we have determined that the interaction between the metal sites and oxygen-containing intermediates primarily depends on orbital energy levels before being further evaluated by bond order involving electronic modulation. This finding may offer a valuable insight for future research in related electrocatalysis fields. The Cr=N 2 =Fe catalyst exhibits higher ORR catalytic capability than commercial Pt/C, thus driving stable operation of the assembled zinc-air battery for over 300 h. This study found that the interaction between metal sites and oxygen intermediates mainly depends on orbital energy levels before being further evaluated by bond order involving electronic regulation. The introduction of the Cr centers perturbs the valence band of the entire material, providing the possibility for improving ORR activity.