Pd and Pd−Cu Bimetallic Particles Prepared by Decomposition of Organic Precursors on Clean MgO Microcrystals

Abstract

Pd and bimetallic Pd−Cu particles are prepared by decomposition of acetylacetonate precursors on clean MgO microcubes. Large Pd particles (>8 nm) are found with an octahedral shape asymmetrically truncated at the top and at the interface, epitaxially (001) and (110) oriented on MgO. Both the dislocations in the Pd lattice and the reentrant angles at the interface indicate a low interaction with the substrate. Small particles (<5 nm) are half octahedral truncated at the top. They are (001) oriented on the MgO surface and accommodated at the interface, as in the case of the particles prepared by ultrahigh vacuum (UHV) condensation. Bimetallic Pd−Cu particles are homogeneous in composition (50% Pd−50% Cu), with perfectly ordered CsCl structure, as in the case of the particles prepared by simultaneous condensation of Pd and Cu under UHV and high-temperature annealing. They are (001) oriented on MgO.