Cu2+ underpotential-deposition assisted synthesis of Au and Au-Pd alloy nanocrystals with systematic shape evolution

The syntheses of noble metal nanocrystals (NCs) with systematic shape evolution have received extensive attention in the research on nanomaterials. The introduction of foreign metal ions was one of the most effective ways to control the shape of the noble metals. However, most of the reports on the shape influence of foreign metal ions have focused on Ag+. Herein, we systematically investigated the influence of Cu2+ on the structure evolution of Au NCs by forming an underpotential deposition atom layer on the metal surface. The growth rate of atoms on high-index surfaces became more rapid than that on low-index facets, which caused the NCs to evolve from trioctahedral to cubic and octahedral structures. In addition, by regulating the given amount of Cu, Au-Pd alloy NCs with different morphologies can also be prepared. Furthermore, we found that the as-prepared HOH and cubic Au-Pd alloy NCs exhibited excellent performance in formic acid electro-oxidation in comparison with Pd black.