High Activity and Stability of Pt2Bi Catalyst in Formic Acid Oxidation

摘要

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 CO_(ads) stripping voltam-metry (surface composition). Bulk composition of Pt2Bi revealed two phases-55% PtBi alloy and 45% Ft. Estimated contribution of pure Ft on the Ft2Bi surface (43.5%) determined by CO_(ads) stripping voltammetry corresponds closely to bulk composition. Ft2Bi 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 Ft2Bi 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. Ft2Bi 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 ~0.2 V to more negative value relative to Ft under steady-state condition.