In the following sections, we delve into the details of the FDT-SJM implementation, providing insights into its advantages in computational electrochemistry; and we discuss the obtained results from the simulations of Au(111) interfaces in pure water and alkaline solutions (LiOH, KOH, Li, K). Specifically, we estimate the PZC charge and the EDL ca-pacitance of the systems and compare those to experimental values. Different alkali ions give rise to different interfacial capacitances, which we hypothesize is due to differences in ionic size and interactions with the electrolyte solvent. The comparison to experimental capacitances validates the computational model. Moreover, we also discuss the effect of the applied potentials on the waters' molecular orientation.