Surface engineering is known as an effective strategy to enhance the catalytic properties of Pt-based nanomaterials. Herein, we report on surface engineering Ni-Pt nanoalloys with a facile method by varying the Ni doping concentration and oleylamine/oleic- acid surfactant-mix. The alloy-composition, exposed facet condition, and surface lattice strain are, thereby manipulated to optimize the catalytic efficiency of such nanoalloys for methanol oxidation reaction (MOR). Exemplary nanoalloys including Ni_0.69Pt_0.31 truncated octahedrons, Ni_0.45Pt_0.55 nanomultipods and Ni_0.20Pt_0.80 nanoflowers are thoroughly characterized, with a commercial Pt/C catalyst as a common benchmark. Their variations in MOR catalytic efficiency are significant: 2.2 A/mg_Pt for Ni_0.20Pt_0.80 nanoflowers, 1.2 A/mg_Pt for Ni_0.45Pt_0.55 nanomultipods, 0.7 A/mg_Pt for Ni_0.69Pt_0.31 truncated octahedrons, and 0.6 A/mg_Pt for the commercial Pt/C catalysts. Assisted by density functional theory calculations, we correlate these observed catalysis-variations particularly to the intriguing presence of surface interplanar-strains, such as {111} facets with an interplanar-tensile-strain of 2.6% and {200} facets with an interplanar-tensile-strain of 3.5%, on the Ni_0.20Pt_0.80 nanoflowers.

A simple yet general one-step solvothermal method is applied to synthesize sub-7 nm monodispersed single-crystal NiPt₂ nanoparticles (NPs) with the morphology of truncated octahedrons in the alloying state of disordered atomic arrangements. The effective magnetic moments of these NPs exhibit an anomalous temperature dependency, increasing from approximately 0.9 μ_B/atom at 15 K to 1.9 μ_B/atom at 300 K. This is an increase by a factor of more than three compared with bulk Ni. On the basis of experiments involving X-ray absorption near-edge spectroscopy of the L3 edge for Pt and density functional theory calculations, the observed novel magnetism enhancement and its anomalous temperature dependence are attributed to the electron transfer arising from the thermal-activation effects.