Pt-Ir and Pt-Cu binary alloys as the electrocatalyst for ammonia oxidation

摘要

The electrocatalytic activities of Pt{sub}0.8Ir{sub}0.2, Pt{sub}0.5Cu{sub}0.5, Pt{sub}0.67Cu{sub}0.33, Pt, and Ir for ammonia oxidation have been studied comparatively in KOH solutions by cyclic voltammetry and potentiostatic polarization. The anodic oxidation began on Ir at a lower potential than on Pt by about 0.1 V, whereas the oxidation peak current density on Ir was much lower than that on Pt. On the binary alloy of Pt{sub}0.8Ir{sub}0.2, the oxidation started at slightly lower potential than on Pt, and the peak current density was slightly higher than that on Pt. In contrast, Pt{sub}0.5Cu{sub}0.5 and Pt{sub}0.67Cu{sub}0.33 alloys showed almost the compatible activity inferior to Pt. These facts suggested that alloying in the Pt-Ir binary system may lead to the enhancement of ammonia oxidation activity due to a kind of cooperative interaction between Pt and Ir.