The experiments were conducted on a Pt(111) in 0.1 mM HClO 4 + x mM LiClO 4 . It was found that the valley and the terrace of the measured capacitance curve shifts to lower potentials with increasing concentration of LiClO 4 . In the present model, the shift in the capacitance minimum and terrace is associated with adsorption of OH, as shown in Figure . As for the pure double-layer capacitance in Figure (c), a negative shift in the peak is found, which has been analyzed in the discussion of Figure .