Self-assembled binary mixtures of partially etched nanowires

Arrays of anisotropic particles are sought after for applications in optics, electronics, and energy. Structures assembled from multiple micro- or nanoparticles could incorporate the distinct properties of each component to achieve functions not possible from single-population assemblies. In mixed-particle populations, the assembly forces may differ between the particle types, which will in turn influence the final assembled structures. Here, binary particle mixtures are studied and compared to assemblies formed from each of the component particles alone. The particles are partially etched nanowires (PENs, ≈300 nm diameter, and 3-8 μm overall length), which are formed by the silica coating and subsequent etching of striped metal nanowires, such that what remains are silica nanotubes containing segments of metal core (Au, Pt, Rh, or Pt/Au) with controllable location and number, spaced by "empty" regions that fill with water. Binary mixtures of PENs with different core metals and segment patterns are examined here to explore how the different core segment material, length, position, and number affects overall self-assembly behavior. Study of self-assembled anisotropic particle mixtures has been limited, thus, little is known about the interparticle forces that drive self-assembly. In this work, partially etched nanowires with different particle compositions (core segment material, length, position, and number) are studied to give insight into self-assembly.