In the H = 16.75 Å system, for example, 62% of chloride ions and 33% of sodium ions reside in the first adsorption layer (see Fig. ). This behavior is in qualitative agreement with recent AIMD simulations of single ions confined within 1 nm graphene slit pores. The authors attributed the enrichment of chloride at the surface relative to the sodium ions to chloride's lower hydration energy, making it more likely to partially desolvate and adsorb. These hydration effects appear to dominate over ion-carbon interactions, as sodium ions have been shown to bind to graphene more strongly than chloride in gas-phase DFT calculations. 6 Having obtained a general picture of the structure in our nanoconfined electrolytes through the density profiles, we now proceed to characterizing ion-ion interactions. We quantify ion pairing behavior using the potential of mean force (PMF), shown in Fig. .