Graphene-based electrodes have recently gained popularity due to their superior electrochemical properties. However, the exact mechanisms of electrochemical activity are not yet understood. Here, we present data from NADH oxidation and ferri/ferrocyanide redox probe experiments to demonstrate that both (i) the porosity of the graphene electrodes, as effected by the packing morphology, and (ii) the functional group and the lattice defect concentration play a significant role on their electrochemical performance.