Atomic-scaled surface engineering Ni-Pt nanoalloys towards enhanced catalytic efficiency for methanol oxidation reaction

摘要

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/oleicacid 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_(0.69)Pt_(0.31)truncated octahedrons,Ni_(0.45)Pt_(0.55)nanomultipods and Ni_(0.20)Pt_(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/mgPt for Ni_(0.20)Pt_(0.80)nanoflowers,1.2 A/mgPt for Ni_(0.45)Pt_(0.55)nanomultipods,0.7 A/mgPt for Ni_(0.69)Pt_(0.31)truncated octahedrons,and 0.6 A/mgPt 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_(0.20)Pt_(0.80)nanoflowers.