Synthesis of quasi-concave pt-Ni nanoalloys via overgrowth and their catalytic performance towards methanol oxidation

Quasi-concave Pt- Ni alloy nanostructures were synthesized via a solvothermal method, and were thought to form by epitaxial growth on the 12 vertexes of a cuboctahedron. A simultaneous etchingovergrowth process was proposed to illustrate the growth mechanism. The epitaxial layer was of different composition from the core, as confirmed by high- resolution transmission electron microscopy, selectedarea electron diffraction and powder X-ray diffraction characterizations. The concave structures exhibited high catalytic activity towards methanol oxidation. The mass- normalized catalytic activity of the concave products was ~3 times that of pure Pt nanoparticles synthesized under similar conditions, and 13.6 times that of commercial Pt/C. X- ray photoelectron spectroscopy characterization indicated that the binding energy of the concave structures shifted to lower energy, relative to the pure Pt. The modified electronic structure by introducing Ni was thought to be responsible for the enhanced catalytic activity.