High Activity and Stability of Pt2Bi Catalyst in Formic Acid Oxidation

Abstract

Formic acid oxidation was studied on a new prepared Pt2Bi characterized by X-ray diffraction spectroscopy (phase composition), scanning tunneling microscopy (STM) (surface morphology), and COads stripping voltammetry (surface composition). Bulk composition of Pt2Bi revealed two phases-55% PtBi alloy and 45% Pt. Estimated contribution of pure Pt on the Pt2Bi surface (43.5%) determined by COads stripping voltammetry corresponds closely to bulk composition. Pt2Bi reveals high activity and stability in formic acid oxidation. High activity originates from the fact that formic acid oxidation proceeds completely through dehydrogenation path based on an ensemble effect. The high stability of Pt2Bi surface is induced by the suppression of Bi leaching as it was evidenced by insignificant changes of surface morphology and surface roughness shown by STM images before and after electrochemical treatment in formic acid containing solution. Pt2Bi is found to be powerful catalyst exhibiting up to two orders of magnitude larger current densities at 0.0 V and onset potential shifted for similar to 0.2 V to more negative value relative to Pt under steady-state condition.