## 3 Results
### Electrochemical Behavior of Ti Gr. 2 in Presence of Clays  
To quantitatively assess the corrosion behavior of Ti Gr. 2 electrodes in alkaline media and the presence of clays, electrochemical linear polarization curves were carried out. Figure 6 depicts polarization curves (Figure 6a) and Tafel curves (Figure 6b) obtained for Ti Gr. 2 immersed in 0.5 M NaCl in the absence and presence of clays. Additionally, the figure shows a comparison between experimental values (dotted lines) and fitted values (continuous lines) obtained by applying the superposition model according to Equation (2), given RMSE values of 3 \(\times\) 10\({}^{-3}\), 8 \(\times\) 10\({}^{-4}\), 3 \(\times\) 10\({}^{-3}\), and 2 \(\times\) 10\({}^{-3}\), for kaolinite, montmorillonite, 1:1 mixed clay, and pure NaCl solution, respectively. Table 3 summarizes the electrochemical and corrosion parameters determined for ORR, HER, and TOR by using Equations (3)-(5). The electrochemical results provide novel information related to the performance of Ti Gr. 2 used for both electrodes in contact with a 0.5 M NaCl solution with a suspension of kaolinite and montmorillonite clays. At potentials with more negatives than \(-\)800 mV/SHE [29; 44], the HER, which dominates the current density, reveals an important reduction in the current density in the presence of clays compared with a pure solution of 0.5 M NaCl. Considering a fixed cathodic potential of \(-\)900 mV/SHE, the total current densities were 3.87, 5.53, and 9.24 A/m\({}^{2}\) for montmorillonite, kaolinite, and the mixture of both clays, respectively, which are low values compared with 15 A/m\({}^{2}\) for a solution in the absence of clays and containing only NaCl. These variations are in concordance with a smaller Tafel slope value for the test without clays, which also could be due to the adsorption of soluble species from clay samples, disfavoring the electrocatalytic capacity for hydrogen production from water electrolysis. Further, as expected, the entire cathodic branch for Ti Gr. 2 in 0.5 M NaCl was found to be higher compared with the presence of clays, which revealed lower current densities. The \(i_{0,Tl}\) is significantly higher in the mixture of kaolinite and montmorillonite (1:1), indicating greater reactivity under this condition. In comparison, suspensions containing only kaolinite or montmorillonite exhibit much lower values, although still higher than that of the 0.5 M NaCl base solution. The mixture (1:1) also shows the highest \(i_{0,O_{2}}\), suggesting an increase in electrochemical reactivity compared to suspensions containing only one type of clay. The \(\mid\)\(i_{0,2}\)\(\mid\) is higher for the mixture (1:1) than other slurries and NaCl solutions, indicating a greater ease for the ORR to occur under these conditions. The \(i_{0,H_{2}}\) is similar between the base solution and the clay suspensions but is lower in solutions containing only kaolinite or montmorillonite, especially in the montmorillonite suspension. These results indicate a slight decrease in the kinetics under equilibrium conditions. The \(t_{H_{2}}\) is more negative in suspensions with kaolinite and montmorillonite, which could indicate a greater tendency for HER under these conditions. Regarding the ORR, the polarization curves showed a good adjustment to a mixed kinetic by charge and mass transfer (see Equation (4)), where the limiting current density (\(i_{l,O_{2}}\)) trends to decrease in the presence of clays from 13.68 A/m\({}^{2}\) in NaCl solution to 3.8 A/m\({}^{2}\) in the presence of montmorillonite clay. These variations in \(i_{l,O_{2}}\) values for ORR represent a decay in the mass transfer of oxygen dissolved close to 28, 35, and 61% when the Ti Gr. 2 is in contact with slurries of montmorillonite, kaolinite, and the mix 1:1 of both clays, respectively, compared to a pure NaCl solution. The decreased oxygen mass transfer from bulk to metallic surface could be associated with changes in the density and viscosity