Phase Engineering of Intermetallic PtBi₂ Nanoplates for Formic Acid Electrochemical Oxidation.

Abstract

Phase engineering of Pt-based intermetallic catalysts has been demonstrated as a promising strategy to optimize catalytic properties for a direct formic acid fuel cell. Pt-Bi intermetallic catalysts are attracting increasing interest due to their high catalytic activity, especially for inhibiting CO poisoning. However, the phase transformation and synthesis of intermetallic compounds usually occurring at high temperatures leads to a lack of control of the size and composition. Here, we report the synthesis of intermetallic β-PtBi₂ and γ-PtBi₂ two-dimensional nanoplates with controlled sizes and compositions under mild conditions. The different phases of intermetallic PtBi₂ can significantly affect the catalytic performance of the formic acid oxidation reaction (FAOR). The obtained β-PtBi₂ nanoplates exhibit an excellent mass activity of 1.1 ± 0.01 A mg_Pt^-1 for the FAOR, which is 30-fold higher than that of commercial Pt/C catalysts. Moreover, intermetallic PtBi₂ demonstrates high tolerance to CO poisoning, as confirmed by <i>in situ</i> infrared absorption spectroscopy.