Aqueous Synthesis of Pd–M (M = Pd, Pt, and Au) Decahedra with Concave Facets for Catalytic Applications

Noble-metal nanocrystals with structural features such as high-index facets and twin defects on the surface are desirable for various catalytic applications. Here we report an aqueous route to the facile synthesis of Pd–M (M = Pd, Pt, and Au) decahedra covered with concave facets by controlling the deposition and diffusion of M atoms on Pd decahedral seeds. Our mechanistic studies indicate that the preferential deposition of M atoms on the twin boundaries of Pd decahedral seeds under limited surface diffusion is instrumental to their evolution into decahedra enclosed by concave facets. Due to the presence of high-index facets and twin boundaries on the surface, the Pd concave decahedra show enhanced catalytic activity towards formic acid oxidation. The present work not only offers a general route to the facile synthesis of decahedral nanocrystals with concave facets but also provides an additional knob for enhancing the catalytic performance of noble-metal nanocrystals.