Figure 2

pH calculation using the CCS for \({\mathrm {pH}} \ge 7.6\) and the HH equation for \({\mathrm {pH}}< 7.6\). (a) pH dependent CCS at \(10\,^{\circ }\hbox {C}\). Data points are marked by crosses and the fitted sigmoidal function by a solid line. (b, c) pH values as a function of time for initial electrolyte concentration of 0.1 M (b) and 1 M (c). Data points represent average value of experiments with an applied potential of \(-1.07\,{\mathrm {V}}\) (dark blue), \(-1.37\,{\mathrm {V}}\) (light blue) and \(-1.67\,{\mathrm {V}}\) (green). Coloured areas show minimum and maximum value of the respective data point in two repetitions of the experiments. Further data representing experiments at other potentials are available in Fig. S5.