## 3 Results
### Electrochemistry
In the presence of the AM dye for the same potential, the features observed in the Nyquist impedance plot (red) corresponded to the initial phase of the dye electrooxidation (for high-frequency arc), while middle-frequency and low-frequency features could be assigned to finite-length diffusion related to surface porosity [18; 38]. Thus, for the first oxidation peak (Figure 2), the recorded charge transfer resistance (\(R_{\text{ct}}\)) parameter for AM oxidation came to \(108\)\(\Omega\) cm\({}^{2}\), whereas the recorded porosity resistance (\(R_{\text{p}}\)) of the electrode's surface reached \(11\),\(636\)\(\Omega\) cm\({}^{2}\). Moreover, the corresponding interfacial capacitance (\(C_{\text{dl}}\)) and pseudocapacitance (\(C_{\text{p}}\)) parameters reached \(2.21\) and \(1535\)\(\mu\)F cm\({}^{-2}\), respectively (see equivalent circuits used to fit the recorded data in Figure 4A). Figure 2: Cyclic voltammetry behavior of the graphite electrode in the absence and presence of AM dye (at \(50\) mg dm\({}^{-3}\)), recorded in \(0.054\) M Na\({}_{2}\)SO\({}_{4}\) supporting electrolyte, at a sweep rate of \(50\) mV s\({}^{-1}\) and \(293\) K.  
Then, only porosity response was observed in a pure supporting solution at the potential of 150 mV vs. SCE (Figure 3B, blue plot). On the other hand, in the AM-containing solution (red) for the same potential (corresponding to the second oxidation peak, see Figure 2), a high-frequency semicircle appeared, which could be associated with the process of dye electrooxidation. At the same time, middle-frequency and low-frequency features can be assigned to diffusion and porosity phenomena. Here, the \(R_{\text{ct}}\) parameter came to 74 \(\Omega\) cm\({}^{2}\), and the \(C_{\text{dl}}\) and \(C_{\text{p}}\) parameter reached 4.04 and 2218 \(\mu\)F cm\({}^{-2}\) (see equivalent circuits used to fit the recorded data in Figure 4B). Thus, the \(R_{\text{ct}}\) parameter corresponding to the oxidative electrodeposition of the dye components diminished by about 30% for the peak potential points. The above reactivity increase aligns with the noted augmentation of recorded capacitance parameters by 1.8\(\times\) and 0.7\(\times\), correspondingly for \(C_{\text{dl}}\) and \(C_{\text{p}}\). The above also aligns with previously obtained results in Fe/Cu galvanic cell [18]. The \(R_{\text{ct}}\) parameter's decrease is associated with the  
Figure 4: Equivalent circuit models used for fitting the obtained AC impedance spectroscopy data, where \(R_{\text{s}}\) is solution resistance; \(C_{\text{dl}}\) is double-layer capacitance; \(R_{\text{ct}}\) is charge-transfer resistance parameter for electrooxidation AM dye molecule; W is Warburg element used to account for finite-length diffusion; (**A**) \(R_{\text{p}}\) and \(C_{\text{p}}\) are porosity resistance and pseudocapacitance parameters, respectively; (**B**) \(C_{\text{p}}\) is the pseudocapacitance parameter. In addition, the circuits include constant phase elements (CPEs) to account for the distributed capacitance. Figure 3: The recorded complex plane Nyquist impedance plots for a graphite electrode in contact with pure Na\({}_{2}\)SO\({}_{4}\) and AM-modified (50 mg dm\({}^{-3}\)) solution, where (**A**) corresponds to the potential of \(-\)250 mV vs. SCE and (**B**) corresponds to the potential of 150 mV vs. SCE. The solid lines correspond to the data representation according to the equivalent circuit model presented in Figure 4.  
facilitation of the oxidation process with rising potential, whereas the augmentation of the capacitance values could be associated with the adsorption of oxidation's products on the surface of the electrode. Alternatively, the EIS results for the pure Na\({}_{2}\)SO\({}_{4}\) solution were omitted, as they did not provide any insights into the process of electrooxidation of the examined dye at the investigated potentials. Therefore, they were presented only in graphs to show the difference in the EIS response between pure and AM-modified supporting solutions.