Kinetically Controlled Synthesis of Pd-Cu Janus Nanocrystals with Enriched Surface Structures and Enhanced Catalytic Activities toward CO

Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a facile synthesis of Pd-Cu Janus nanocrystals with controlled shapes through site-selected growth by reducing the Cu(II) precursor with glucose in the presence of hexadecylamine and Pd icosahedral seeds. Specifically, at a slow reduction rate, the Cu atoms nucleate and grow from one vertex of the icosahedral seed to form a penta-twinned Janus nanocrystal in the shape of a pentagonal bipyramid or decahedron. At a fast reduction rate, in contrast, the Cu atoms can directly nucleate from or diffuse to the edge of the icosahedral seed for the generation of a singly twinned Janus nanocrystal in the shape of a truncated bitetrahedron. The segregation of two elements and the presence of twin boundaries on the surface make the Pd-Cu Janus nanocrystals effective catalysts for the electrochemical reduction of CO