Advanced bimetallic In–Cu/Ag/Au nanostructuresvia microemulsion-based reaction

Abstract

Bimetallic nanomaterials and nanostructures constituted of the coinage metals (Cu, Ag, Au) and indium with elaborate compositions and structures are realized via a microemulsion-based approach. In detail, this comprises Cu₁₁In₉@CuIn@In core@shell-A@shell-B nanoparticles, In-Ag Janushead-like nanoparticles, Ag⁰ hollow spheres, Ag₃In@In core@shell nanoparticles, Au@AuIn₂@In core@shell-A@shell-B nanoparticles and AuIn₂ nanoparticles. To obtain these advanced architectures, two approaches are applied: (1) In⁰ nanoparticles—pre-synthesized in a microemulsion—were reacted in a follow-up reaction with CuCl₂·2H₂O, AgNO₃ or KAuCl₄; (2) simultaneous co-reduction of InCl₃·4H₂O together with CuCl₂·2H₂O, AgNO₃ or KAuCl₄ in a microemulsion. Characterization of the resulting advanced structures and compositions requires elaborate electron microscopy techniques, combined with energy dispersive X-ray spectroscopy for chemical analyses of single nanoparticles as well as X-ray powder diffraction and optical spectroscopy. The versatility of the experimental approach toward complex nanoparticle architectures is related to a precise control and fine-tuning of the experimental conditions. The resulting tool kit of In–Cu/In–Ag/In–Au-based bimetallic and intermetallic nanomaterials and, in general, of nanostructured metal architectures with such variability and complexity have not yet been described.