Effect of Monovalent Cations on the HOR/HER Activity for Pt in Alkaline Environment

The sluggish kinetics of hydrogen oxidation/evolution reaction (HOR/HER) is one of the major barriers for the breakthrough of alkaline membrane fuel cells. In particular, the effects of different cations on the HOR/HER kinetics are poorly understood to date. In this work, the catalytic HOR/HER activity on polycrystalline platinum (poly-Pt) and high surface area carbon-supported platinum nanoparticles (HSAC-Pt) in various alkaline 0.1 M electrolyte solutions (MOH, M = Li+, Na+ and K+) at different temperatures was studied using rotating disc electrode (RDE) technique. Our results show the increase of the HOR/HER activity for Pt in the order of K+ < Na+ < Li+. The improved kinetics are attributed to the water arrangement controlled by the monovalent cations resulting in non-covalent interactions of the hydrated cations and the adsorbed hydrogen. We assume that these non-covalent interactions cause the superior HOR/HER activity on the Pt surface in presence of LiOH.