Controlled growth of Au/Ni bimetallic nanocrystals with different nanostructures

Bimetallic nanomaterials are of great significance to both fundamental research and industrial applications. Their physicochemical performances are critically dependent on their architectures and electronic structures. Here, it was reported a controlled synthesis of Au/Ni bimetallic nanocrystals with different nanostructures, i.e., dumbbell, core@shell and alloyed nanostructures in a one-pot synthesis procedure. Detailed structural characterizations were conducted with the combination of transmission electron microscopy (TEM) and X-ray diffraction (XRD). Even there is a large lattice mismatch between Au and Ni, Au@Ni core@shell nanocrystals are obtained with the seeded growth method. The growth mechanism was deeply investigated. Triphenylphosphine is demonstrated to be an effective capping agent to modify the interfacial energy to form core@shell nanocrystals, and the higher temperature is proved to be a key role in obtaining alloyed nanocrystals. Au/Ni bimetallic nanocrystals with different architectures, i.e., dumbbell-like, core@shell and alloyed structures, were controlled synthesized through seeded growth method. Growth mechanism investigation suggests that the capping effect of TPP is beneficial for balancing the interfacial energy to support the growth of Ni shell on the surface of Au nanoparticles. The high temperature induces the migration of Au and Ni atoms to form alloyed nanocrystals.