Methanol electro-oxidation reaction at the interface of (bi)-metallic (PtNi) synthesized nanoparticles supported on carbon Vulcan

Ni-rich PtNi bi-metallic catalyst and its counterpart free of nickel supported on carbon Vulcan have been synthesized by the impregnation methodology from Na₂PtCl₆ and Ni(C₅H₇O₂)₂ as precursors. The obtained materials Pt/C and PtNi/C were used as electrocatalysts for the methanol oxidation reaction (MOR) in acid conditions. Electrochemical evaluations demonstrated that the addition of Ni in the Pt-Vulcan matrix promotes an important increment in the faradic current during MOR of one order of magnitude, even though the platinum load is lower in the bi-metallic catalyst. These results suggest that the incorporation of nickel promotes some structural and electronic modifications that enhance a better reaction performance at the electrode interface. Morphological characterization using scanning electron microscopy and transmission electron microscopy with energy dispersive spectroscopy (SEM-TEM-EDS) showed Pt/C and PtNi/C catalysts have a particle size of 5.7 nm and 4.4 nm, respectively. X-ray diffraction (XRD) reveals the formation of Ni₃Pt from the synthesis of PtNi catalysts. Additionally, X-ray photoelectron spectroscopy (XPS) confirmed the presence of Pt and Ni in their metallic-oxidation states on the carbon surface.