Cobalt porphyrin supported on graphene/Ni (111) surface: Enhanced oxygen evolution/reduction reaction and the role of electron coupling

Metal porphyrins have received sustained attention due to their remarkable catalytic properties. However, the catalytic activities of porphyrins are still moderate for oxygen reduction /evolution (ORR/OER) due to the high binding energies between the catalyst and reactant. Herein, we propose a novel strategy to modulate the binding energies of the oxygenated intermediates by introducing electron coupling between the substrate and the metal porphyrin. Our results reveal remarkable enhancement of OER/ORR performance when the Co-porphyrin molecule is supported on the graphene/Ni (111) substrate. The ORR/OER overpotentials can be greatly reduced, in particular for ORR from 0.6 V to 0.31 V. The enhanced ORR/OER activity of Co-porphyrin/graphene/Ni system stems from the electronic coupling between the catalyst and the substrate that modulates the binding strength between catalytic active sites and the reaction intermediates. Our study represents an efficient strategy to design low-cost, high performance, bifunctional electrocatalysts for the application in rechargeable metal-air batteries.