## 3 Results and Discussion
### Ac. Impedance Spectroscopy
Then, the addition of acetone into the supporting solution caused a gradual diminution of the \(R_{\rm ct}\) parameter, where, for the acetone concentrations of 1.0 \(\times\) 10\({}^{-7}\) and 1.0 \(\times\) 10\({}^{-3}\) M, the recorded resistance values of 502.0 and 430.1 \(\Omega\) cm\({}^{2}\) (at \(-\)50 mV), and 7.4 and 6.7 \(\Omega\) cm\({}^{2}\) (at \(-\)500 mV), exhibited a 2.1\(\times\) and 2.5\(\times\), and 1.04\(\times\) and 1.1\(\times\)\(R_{\rm ct}\) reduction, correspondingly. The highest decrease in the charge transfer resistance was understandably recorded at low overpotential values, where the HER undergoes kinetic control. This behaviour (as recently argued for the polycrystalline Pt electrode by [PERSON] et al. in [PERSON] et al. (2016)) is believed to result from the reduction in the solution's surface tension phenomenon, caused by considerably amplified H bonding interactions between (CH\({}_{3}\))\({}_{2}\)C=O and H\({}_{2}\)O molecules. The latter tends to facilitate the process of the H\({}_{2}\) gas bubbles' disagreement from the electrode surface, thus increasing the electrochemically accessible Ni electrode surface area. This interpretation is further reinforced by the observed rise in \(C_{\rm dl}\) values upon increasing acetone concentration, especially at very low overpotentials (see Table 1 for details). It should also be stressed here that the significance of this nickel electrode study does not only rely on its technological importance for the process of alkaline water electrolysis, but also on nickel's low susceptibility to the surface-induced reduction-oxidation and electrosorption phenomena involving organic molecules. In this respect, nickel stands in total contradiction to platinum and Pt-based electrocatalysts (see, e.g., [PERSON] et al. (2016); [PERSON] et al. (2016)). The _ac._ impedance spectra for the oxygen evolution reaction were recorded over a potential window of 1550 to 2000 mV vs. RHE. As for the HER, the obtained Nyquist impedance plots constitute single and somewhat distorted semicircles (Figure 6). Hence, for the acetone-free NaOH solution, the \(R_{\rm ct}\) parameter diminished from 74.1 \(\Omega\) cm\({}^{2}\) (at 1550 mV) to 2.4 \(\Omega\) cm\({}^{2}\) at 2000 mV (compared with the OER impedance results reported in [PERSON] et al. (2016)). Again, the introduction of acetone (compared with the two extreme acetone concentrations) resulted in considerable diminution of the charge transfer resistance, reaching 28.5 and 24.9 \(\Omega\) cm\({}^{2}\) (at 1550 mV), and 2.3 and 2.2 \(\Omega\) cm\({}^{2}\) at 2000 mV (Table 2). The above translates to a \(R_{\rm ct}\) reduction by ca. 2.6\(\times\) and 3.0\(\times\), and 1.04\(\times\) and 1.1\(\times\), correspondingly. Furthermore, the \(C_{\rm dl}\) parameter exhibited significant augmentation [e.g., from ca. 2410 \(\mu\)cm\({}^{-2}\) (unmodified NaOH) to 7390 \(\mu\)F cm\({}^{-2}\) (for acetone concentration of 1.0 \(\times\) 10\({}^{-3}\) M) at the electrode potential of 2000 mV] for the OER measurements conducted at gradually rising acetone concentrations. \begin{table}
\begin{tabular}{c c c} \hline \multicolumn{3}{c}{**0.1 M NaOH + 1.0 \(\times\) 10\({}^{-3}\) M acetone**} \\ \hline
1550 & 24.9 \(\pm\) 0.1 & 6070.5 \(\pm\) 31.3 \\ \hline
1600 & 11.2 \(\pm\) 0.0 & 5906.9 \(\pm\) 53.5 \\ \hline
1650 & 7.0 \(\pm\) 0.0 & 6116.9 \(\pm\) 94.7 \\ \hline
1700 & 5.3 \(\pm\) 0.1 & 5783.4 \(\pm\) 250.5 \\ \hline
1750 & 4.5 \(\pm\) 0.1 & 6303.2 \(\pm\) 202.7 \\ \hline
1800 & 3.7 \(\pm\) 0.0 & 6324.7 \(\pm\) 208.0 \\ \hline
1850 & 2.7 \(\pm\) 0.1 & 4525.9 \(\pm\) 552.1 \\ \hline
1900 & 2.6 \(\pm\) 0.1 & 4982.4 \(\pm\) 125.2 \\ \hline
1950 & 2.2 \(\pm\) 0.1 & 4573.2 \(\pm\) 356.6 \\ \hline
2000 & 2.2 \(\pm\) 0.1 & 7389.7 \(\pm\) 1254.1 \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._