Surface Adsorption Affects the Performance of Alkaline Anion-Exchange Membrane Fuel Cells

Material interactions at the polymer electrolytes-catalyst interface play a significant role in the catalytic efficiency of alkaline anion-exchange membrane fuel cells (AEMFCs). In this work, the surface adsorption behaviors of the cation-hydroxide-water and phenyl groups of polymer electrolytes on Pd- and Pt-based catalysts are investigated using two Pd-based hydrogen oxidation catalysts - Pd/C and Pd/C-CeO2 - and two Pt-based catalysts - Pt/C and Pt-Ru/C. The rotating disk electrode study and complementary density functional theory calculations indicate that relatively low coadsorption of cation-hydroxide-water of the Pd-based catalysts enhances the hydrogen oxidation activity, yet substantial hydrogenation of the surface adsorbed phenyl groups reduces the hydrogen oxidation activity. The adsorption-driven interfacial behaviors of the Pd- and Pt-based catalysts correlate well with the AEMFC performance and short-term stability. This study gives insight into the potential use of non-Pt hydrogen oxidation reaction catalysts that have different surface adsorption characteristics in advanced AEMFCs.