Design of Robust and Reactive Nanoparticles with Atomic Precision: 13Ag-Ih and 12Ag−1X (X = Pd, Pt, Au, Ni, or Cu) Core−Shell Nanoparticles

• Published in: Journal of physical chemistry. C 2009-09, Vol.113 (35), p.15559-15564
• Main Authors: Kim, Hyun You, Kim, Da Hye, Ryu, Ji Hoon, Lee, Hyuck Mo
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp905047h

Density functional theory calculations and a modified reaction model confirm that the initial high CO oxidation reactivity of a 13Ag-Ih nanoparticle from an icosahedron (Ih) structure is immediately diminished as the nanoparticle is transformed to an amorphous state by a reaction-driven structural change. The adsorption of O2 and the formation of a four-center intermediate metastable state from coadsorbed CO and O2 positively charge the 13Ag-Ih nanoparticle, and the repulsive force between the Ag atoms causes the reaction-driven structural change of the 13Ag-Ih nanoparticle. When one central Ag atom is substituted with a solute atom, a core−shell type of 12Ag−1X-Ih (X = Pd, Pt, Au, Ni, or Cu) bimetallic nanoparticle is stabilized. Among them, we propose the 12Ag−1Pd nanoparticle as a robust and reactive Ag-based bimetallic nanoparticle for CO oxidation. The results show that the structural fluxionality accounts for the catalytic activity of small nanoparticles.