Investigations of fuel cell reactions at the composite microelectrode|solid polymer electrolyte interface. I. Hydrogen oxidation at the nanostructured Pt|Nafion® membrane interface

Analysis of effective surface area for electrochemical reaction derived from mass transport property

“…The current density increased with potential and reached a limiting current density below 0.2 V and looked independent of potential up to about 0.8 V. Then, the current density started to decrease and kept decreasing to the maximum potential. A similar trend was reported in the literature for both aqueous electrochemistry [18,19] and solid-state electrochemistry utilizing a solid polymer electrolyte [14,20]. In our past work [10], it was verified that the loss of the HOR current in the high potential region is not caused by the suppression of the inherent Pt activity for HOR of individual sites but caused by site blocking.…”

Oxygen reduction at the silver/hydroxide-exchange membrane interface

“…This suggests that the shift in ½ -wave potential is due to the reduced coverage of oxide/hydroxide on the Ag surface at high potentials, providing a larger number of reaction sites. Changes of coverage of oxide as a function of electrolyte have been observed before, most notably platinum [2], however in that case OH adsorption commences at lower potential when the Pt is in contact with the solid electrolyte.…”

“…In all experiments, the counter electrode was a platinum disk and the reference electrode was a dynamic hydrogen electrode (DHE) [2,9]. For the experiments in sodium hydroxide electrolyte, a three compartment cell was used with a Luggin capillary for the reference arm and a glass frit between the counter electrode compartment and the main cell.…”

“…For the experiments in sodium hydroxide electrolyte, a three compartment cell was used with a Luggin capillary for the reference arm and a glass frit between the counter electrode compartment and the main cell. For the experiments at the AAEM60 membrane, a solid-state cell was used, as described by Jiang et al [2,9]. Figure 1 shows the base voltammogram of a silver nanopowder modified microelectrode cycled at an anionic-exchange membrane, AAEM60.…”

“…However, the presence of adsorbing anions in liquid electrolytes results in competitive adsorption on the metal catalyst surface [1], which can lower the rate of reactions such as the orr. In solid polymer electrolytes, where ions are not freely mobile, electrode kinetics may differ greatly [2]. It is therefore important to study catalysis at solid polymer electrolyte interfaces.…”