Graphene electrochemistry: ‘Adiabaticity’ of electron transfer

Graphene materials currently open new perspectives to electrochemical systems, providing high electron transfer rates, electrochemical stability in a wide potential range, and ability to control these properties, for instance, by introducing impurity atoms. One of the most important electrochemical characteristics of the graphene is the heterogeneous electron transfer rate (or electrochemical activity). However, contradictory results have been presented on the electrochemical activity of graphene, and how structural defects, the number of graphene layers, and the graphene substrate alter its activity. We found here that the question of an electron transfer regime on graphene, which is disputable and rarely considered, is critically important in understanding its electrochemical activity. We provide an evidence of different electron transfer regimes for O 2 /O 2 − and ferrocenium/ferrocene redox on the graphene electrode, that result in different structure-activity relationships. Our results contribute to further understanding of the graphene electrochemistry.