Structural effects on the enhancement of ORR activity on Pt single-crystal electrodes modified with alkylamines

Abstract

We have studied Pt surfaces for which activity towards the oxygen reduction reaction (ORR) is enhanced by adsorbed amines: octylamine (OA) and an alkyl amine containing a pyrene ring (PA). Adsorbed OA/PA (molar ratio 9/1) enhances activity for ORR on n(111)–(111) surfaces of Pt for terrace atomic rows n greater than 7. The activity on Pt(111), the surface of which is a flat terrace, is particularly enhanced. On Pt(100), which also has a flat terrace, however, the ORR activity is greatly reduced. It is shown that adsorbed OA/PA enhances the ORR on surfaces with a wide (111) terrace, but deactivates the ORR on the (100) terrace.