Abstract
The contamination impacts of ethylene glycol (EG) and caprolactam on the electro-catalytic behavior of a Pt/C catalyst toward the oxygen reduction reaction (ORR) were investigated in acid media using a rotating ring/disk electrode (RRDE). The Pt surface coverage increased whereas the ORR diffusion-limited and kinetic currents decreased with larger EG and caprolactam concentrations. The poisoning effect of caprolactam on the ORR was more severe than EG. The Tafel slope was unchanged for EG but higher values were observed when the caprolactam concentration increased to 10-1 M. The H2O2 yield greatly increased for both contaminants. The ORR performance loss due to EG was attributed to Pt active sites blocked by COad species and EG oxidation by-products. The adsorption of aminocaproic acid resulting from a caprolactam ring-opening reaction onto Pt active sites was responsible for the ORR activity and selectivity effects.
Published Version
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