  Nanoconfinement generally leads to drastic effect on the physical and
chemical properties of ionic liquids. Here we investigate how the
electrochemical reactivity in such media may be impacted inside nanoporous
carbon electrodes. To this end, we study a simple electron transfer reaction
using molecular dynamics simulations. The electrodes are held at constant
electric potential by allowing the atomic charges on the carbon atoms to
fluctuate. We show that the $\mathrm{Fe^{3+}}/\mathrm{Fe^{2+}}$ couple
dissolved in an ionic liquid exhibits a deviation with respect to Marcus
theory. This behavior is rationalized by the stabilization of a solvation state
of the Fe$^{3+}$ cation in the disordered nanoporous electrode that is not
observed in the bulk. The simulation results are fitted with a recently
proposed two solvation state model, which allows us to estimate the effect of
such a deviation on the kinetics of electron transfer inside nanoporous
electrodes.

Materials Science;Chemical Physics