Copper can still be epitaxially deposited on palladium nanocrystals to generate core-shell nanocubes despite their large lattice mismatch

Here we report the synthesis of Pd@Cu core-shell nanocubes via epitaxial growth, where the lattice mismatch is 7.1%. The synthesis involved the use of Pd seeds with different shapes (including cubes, cuboctahedra, and octahedra) for the epitaxial growth of Cu shells. Different from the conventional growth mode, Cu atoms initially nucleated only on a few of the many faces of a Pd seed, onto which more Cu atoms were continuously added to generate Cu blocks. Later, the Cu atoms also started to nucleate and grow on other faces of the Pd seed until the entire surface of the seed was covered by a Cu shell. As a result, the Pd seed was rarely located in the center of each core-shell structure. The final product took a cubic shape enclosed by {100} facets regardless of the type of Pd seeds used because of the selective capping of Cu(100) surface by hexadecylamine. The edge lengths of the Pd@Cu nanocubes could be tuned from 50 to 100 nm by varying the amount of Pd seeds while keeping the amount of CuCl ₂ precursor.