Phase Engineering of Intermetallic PtBi 2 Nanoplates for Formic Acid Electrochemical Oxidation.

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-PtBi 2 and γ-PtBi 2 two-dimensional nanoplates with controlled sizes and compositions under mild conditions. The different phases of intermetallic PtBi 2 can significantly affect the catalytic performance of the formic acid oxidation reaction (FAOR). The obtained β-PtBi 2 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 PtBi 2 demonstrates high tolerance to CO poisoning, as confirmed by in situ infrared absorption spectroscopy.