For the cation that forms a contact-ion pair with CO 2 -, we then performed constrained AIMD simulations at different cation surface distances (Figure ). The cation coordination numbers far from the surface (>5 Å) are within 0.47 of the experimental bulk coordination numbers (Li + : 4 , K + : 6 , and Cs + : 8). Importantly, the coordination analysis revealed an average loss of about one H 2 O molecule as the cations move from OHP (assumed to be at 5 Å) towards the electrode. Therefore, we estimated the energy required for the cations to lose a single water molecule and form the reaction microenvironment, which is considered a elementary step in the MKM. Among the cations Li + has the highest reaction energy followed by K + and Cs + (Figure ) in line with their charge vs. radius ratios. The energy associated with this coordination change and the potential jump across the electric double layer (∆ϕ OHP ) are used to estimate the surface coverage of cations (θ M + ) (SI Section 1.1.2). This is then multiplied by the number of Ag surface sites per unit area to obtain the estimate of the number of active sites in the presence of cations. We note that the water coordination of K + and Cs + close to the surface was around 5 and 6 respectively and dynamic (Figure ), while for Li + it is 3 and more static. The effect of changing the water coordination of K + and Cs + (from 3 to 5 and 6 respectively) on the binding energies of adsorbates was estimated and found to be within 0.13 eV (Figure ) and therefore should not affect the trends observed across cations in the multiscale models.