The defining characteristic of the EDL is the screening of the charge density on the cathode surface with solvated cations in the electrolyte and a concomitant repulsion of anions away from the surface. The nature of the cation therefore plays an important role in determining the structure of the EDL, the strength of electric field, the differential capacitance and the extent of the polarization of solvent molecules. The operating potentials of practical CO 2 ER and other electrocatalytic systems imply that the cations in the EDL will reach their steric limit close to the electrode. This closed-pack nature of the EDL is expected to have significant implications for the energetics of the reactive and non-reactive processes relevant to CO 2 ER. The local reaction environment of CO 2 electrocatalysis is therefore formed by the double layer and more research effort is needed to develop a stronger understanding of the region spanning the first 5 -10 nm from the catalyst surface.