Comparing Hydrogen Oxidation and Evolution Reaction Kinetics on Polycrystalline Platinum in 0.1 M and 1 M KOH

Abstract

Alkaline membrane fuel cells (AMFCs) are attracting increasing attention owing to recent developments in anion-exchange membranes and non-noble-metal O2-reduction catalysts. Despite these promising improvements, the sluggish kinetics of the H2-oxidation reaction (HOR) on Pt imply the need for considerable amounts of this noble metal at the AMFC anode, rendering the system more expensive and ultimately hindering its commercialization. Interestingly, the majority of the works dealing with the kinetics of the HOR on Pt were performed in relatively dilute (0.1 M) alkaline electrolytes with a pH lower than that of the operative AMFC. Wondering whether this difference in OH−-concentration would have a significant effect on the HOR-kinetics, here we report our results on the HOR-activity of polycrystalline Pt in 0.1 M and 1 M KOH. These were derived from rotating disc electrode measurements performed in a temperature-controlled PTFE-cell, which allowed us to estimate reliable values for the exchange current density and activation energy in both alkaline solutions.