Highly Asymmetric, Interfaced Dimers Made of Au Nanoparticles and Bimetallic Nanoshells: Synthesis and Photo-Enhanced Catalysis

Synthesis of a class of exotic interfaced dimers with high asymmetries in terms of composition, morphology, structure (solid versus hollow), and dimension of the individual nanoscale components in the dimers is successfully accomplished. Typical examples include the interfaced dimers made of solid Au nanoparticles and hollow bimetallic nanoshells with different compositions, such as Au/Ag, Pt/Ag, and Pd/Ag. The success of the synthesis relies on the combination of asymmetric overgrowth of Ag nanodomains on the partially passivated Au nanoparticles and a following galvanic replacement reaction between the Ag nanodomains and appropriate noble metal precursors. The entire synthesis is processed on the unique superparamagnetic colloidal substrates that offer many advantages, such as time‐efficiency, scalability, and high yield. The Au nanoparticle and the bimetallic nanoshell in each interfaced dimer are in direct contact, resulting in the possible strong coupling between them as well as novel properties that cannot be observed in either the nanoparticle or the nanoshell. For example, dimers made of Au nanoparticles and Pd/Ag nanoshells exhibit enhanced catalytic performance toward Suzuki coupling reactions under illumination of visible light because the strong surface plasmon resonances in the Au nanoparticles can influence the catalytic activity of the Pd/Ag nanoshells through coupling between the nanoparticles and the nanoshells. Highly asymmetric, interfaced dimers made of solid Au nanoparticles and hollow bimetallic nanoshells with different compositions are synthesized by combining the controlled growth of interfaced Au–Ag dimers and nanoscale galvanic replacement reactions on superparamagnetic colloidal substrates. The direct contact between the Au nanoparticle and the bimetallic nanoshells leads to possible strong couplings and novel properties.