We study the interaction between the TM-Nx and metal-free active sites of a pyrolized TM/N/C catalyst and its effect on their ORR activities. We particularly choose a Fe-N4-edge-graphene and a quaternary-N-doped zigzag edge as representatives of TM-Nx and the metal-free active sites, respectively. We find that the interaction of the Fe-N4 and quaternary-N-doped sites at the zigzag edge of graphene enhances the ORR free energy profile at the quaternary-N-doped site. However, the ORR free energy profile at the Fe-N4 site is not affected by this interaction.