Electrode polarization at the Pd/proton conductor interface

Polarization study of Fe|BaCe0.5Zr0.3Y0.08Yb0.08Cu0.04O3-δ|Fe electrochemical cells in wet H2 atmosphere

“…From the dependence of the I o vs. 1/T, the activation energy was calculated to be 0.55 ± 0.05 eV, while from the dependence of s vs. 1/T (which was obtained by the 4-point technique under reducing conditions), the activation energy was calculated to be 0.25 eV. The apparent activation energy (0.55 ± 0.05 eV) is similar to the activation energy observed in the case of the PdeSrCe 0.95 Yb 0.05 O 3-a system (0.73 eV) [25], the AueSr 0.995 Ce 0.95 Y 0.05 O 2.970 system (0.60 eV), the NieSr 0.995-Ce 0.95 Y 0.05 O 2.970 system (0.70 eV) for the H 2 oxidation, and the PteSr 0.995 Ce 0.95 Y 0.05 O 2.970 system (0.74 eV) [18] while is lower compared to the activation energy observed for the Ag-SCY (1.4 eV) [22] or the AgeSr 0.995 Ce 0.95 Y 0.05 O 2.970 (1.0 eV) system [21]. The activation energy of the exchange current density calculated in the present work can be compared to those reported in literature for metals over SCY electrolyte [23,28].…”

Electrode polarization measurements in the Fe|SrCe0.95Yb0.05O2.975|Au proton conducting solid electrolyte cell

“…Previous studies showed clearly that by using similar operating atmospheres, the proton conducting solid electrolyte cell, used in the present study, is not reported to reduce and to develop electronic conductivity [14,20]. In order to evaluate the effect of mass transport and the appearance of limiting currents, the current-overpotential data are plotted in a linear scale.…”

“…However, in the case of hydrogen oxidation reaction, n equals either to unity or to two depending on the type of hydrogen, either atomic or molecular, that participates in the rate determining step. Nevertheless, as reported in literature, hydrogen is dissociatively adsorbed on the electrode's surface and participates as hydrogen ad-atom in the charge transfer reaction [11][12][13][14][15][16][17][18][19][20]. Consequently, in the following analysis, n is considered equal to unity.…”

“…The solid electrolyte ohmic resistance was estimated by performing AC impendance measurements. It is well-known that at high frequencies the overall resistance tends to become purely ohmic [20]. This high frequency value was used in each case in order to obtain ohmic-free overpotentials:…”

“…Specifically, electrode kinetics has been examined over Au, Ni, Pt, Pd and Ag electrodes [11][12][13][14][15][16][17][18][19][20]. However, comparison of all studies is difficult due to existing differences in experimental conditions, electrode preparation methods and different techniques employed to calculate the ohmic-free overpotentials.…”