Pt-Frame@Ni quasi Core-Shell Concave Octahedral PtNi3 Bimetallic Nanocrystals for Electrocatalytic Methanol Oxidation and Hydrogen Evolution

PtNi3 bimetallic concave octahedrons with a majority of platinum atoms deposited on the frames were synthesized in ethylene glycol solution. The high angle annular dark field scanning transmission electron microscopy (HAAD-STEM) characterizations and energy-dispersive X-ray spectroscopy (EDS) analysis reveal that the Pt frames have a thickness of less than 2 nm, which surround a nickel core thus forming a quasi core-shell concave octahedral nanoparticle (NP). The element-specific anisotropic growth followed by the nanoscale phase segregation and subsequent oxidation of Ni riched facets are responsible for the formation of the concave nanostructure. The PtNi3 quasi core-shell concave octahedrons exhibit substantially enhanced electrocatalytic properties toward methanol oxidation and hydrogen evolution reaction compared with that of the commercial Pt/C, suggesting that the Ni riched Pt-Ni NPs can be used as a potential candidate for methanol oxidation reaction (MOR) or hydrogen evolution reaction (HER) catalysts with the low utilization of Pt.