Model systems for the study of electrocatalysis at the nanoparticle- electrolyte-gas reactant three-phase interface

A method is herein described that enables the sharp, conically-shaped tip of a short Pt wire attached to a conventional scanning tunneling microscope (STM) head to be gradually inserted into a Nafion solid polymer electrolyte membrane. A comparatively much larger Pt electrode placed on the underside of the membrane allows for the area of the Pt tip in contact with the Nafion to be determined by coulometric analysis of the cyclic voltammetric features. Preliminary results have shown that this novel tactic makes it possible to examine clean Pt surfaces involving as few as ca. 94,000 active metal sites to contact Nafion, opening new prospects for probing the Pt|Ionomer|Gas three-phase interface under conditions which replicate those found in fuel cells.