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Benzene Adsorption: A Significant Inhibitor for the Hydrogen Oxidation Reaction in Alkaline Conditions
journal contribution
posted on 2017-09-25, 00:00 authored by Ivana Matanovic, Hoon Taek Chung, Yu Seung KimSlow hydrogen oxidation reaction
(HOR) kinetics on Pt under alkaline
conditions is a significant technical barrier for the development
of high-performance hydroxide exchange membrane fuel cells. Here we
report that benzene adsorption on Pt is a major factor responsible
for the sluggish HOR. Furthermore, we demonstrate that bimetallic
catalysts, such as PtMo/C, PtNi/C, and PtRu/C, can reduce the adsorption
of benzene and thereby improve HOR activity. In particular, the HOR
voltammogram of PtRu/C in 0.1 M benzyl ammonium showed minimal benzene
adsorption. Density functional theory calculations indicate that the
adsorption of benzyl ammonium on the bimetallic PtRu is endergonic
for all four possible orientations of the cation, which explains the
significantly better HOR activity observed for the bimetallic catalysts.
The new HOR inhibition mechanism described here provides insights
for the design of future polymer electrolytes and electrocatalysts
for better-performing polymer membrane-based fuel cells.