Transition-metal based M-N4/C catalysts are appealing for electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).Employing model catalysts,which have well-defined molecular structures and coordination environments,to investigate electrocatalytic performance of M-N4/C sites for ORR and OER is of fundamental significance.Herein,we reported the use of Co tetra (phenyl)porphyrin 1 and Co tetra(pentafluorophenyl)porphyrin 2 as models to probe the role of Co-N4/C sites for oxygen electrocatalysis.We showed that Co porphyrin 1 is more efficient than its structural analogue 2 for oxygen electrocatalysis in alkaline aqueous solutions,indicating that the electronrich Co-N4/C site is more favored when noncovalently adsorbed on carbon supports.This work inspires rational design of reaction-oriented catalysts for sustainable energy storage and conversion technologies.