The electrified Pt(111)|H 2 O interfaces have been built by appointing charges to the platinum slab, thereby premising the established conception of the free charge density being a good approximation of the electrode potential. Here, Gauthier et al. also consider the effective free charge density as descriptor for the electrochemical driving force of processes, being preferable to the work function approach due to its sensitivity to simulation cell sizes. Free charge density (denoted σ Pt 1L ) describes here the actual charge located at the electrode side of the EDL, compensated by the ionic charge in the electrolyte in the absence of specific adsorption of hydrogen or hydroxide. The free charge density curves obtained via laser-induced temperature jump method by Garcia et al. for the Pt(111) surface in 0.1 M HClO 4 serve as reference for introducing the electrode potential in our simulations. Note, via experimental cyclic voltammetric measurements the total charge density is accessibleincluding the charge transferred during adsorption processes (e.g. when chemical bonds are formed). In the following interfacial characterization under double layer potential conditions (E ≤ 0.5 V), we are assuming an adsorbate free surface, therefore the equality of free charge density and total charge density holds true.