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 PtNi3quasi 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.