The fabrication of three-dimensional assemblies consisting of large quantities of nanowires is of great technological importance for various applications including (electro-)catalysis, sensitive sensing, and improvement of electronic devices. Because the spatial distribution of the nanostructured material can strongly influence the properties, architectural design is required in order to use assembled nanowires to their full potential. In addition, special effort has to be dedicated to the development of efficient methods that allow precise control over structural parameters of the nanoscale building blocks as a means of tuning their characteristics. This paper reports the direct synthesis of highly ordered large-area nanowire networks by a method based on hard templates using electrodeposition within nanochannels of ion track-etched polymer membranes. Control over the complexity of the networks and the dimensions of the integrated nanostructures are achieved by a modified template fabrication. The networks possess high surface area and excellent transport properties, turning them into a promising electrocatalyst material as demonstrated by cyclic voltammetry studies on platinum nanowire networks catalyzing methanol oxidation. Our method opens up a new general route for interconnecting nanowires to stable macroscopic network structures of very high integration level that allow easy handling of nanowires while maintaining their connectivity.

We study the transversal and longitudinal localized surface plasmon resonances in single nanowires and nanowire dimers excited by the fast traveling electron beam in a transmission electron microscope equipped with high-resolution electron energy-loss spectroscopy. Bright and dark longitudinal modes up to the fifth order are resolved on individual metallic nanowires. On nanowire dimers, mode splitting into bonding and antibonding is measured up to the third order for several dimers with various aspect ratio and controlled gap size. We observe that the electric field maxima of the bonding modes are shifted toward the gap, while the electric field maxima of the antibonding modes are shifted toward the dimer ends. Finally, we observe that the transversal mode is not detected in the region of the dimer gap and decays away from the rod more rapidly than the longitudinal modes.

We report on the experimental and the theoretical investigation of multipole surface plasmon resonances in metal nanowires conductively connected by small junctions. The influence of a conductive junction on the resonance energies of nanowire dimers was simulated using the finite element method based software CST Microwave Studio and experimentally measured by electron energy-loss spectroscopy in a transmission electron microscope. We extend the analysis of conductively connected structures to higher order multipole modes up to third order, including dark modes. Our results reveal that an increase in junction size does not shift significantly the antibonding modes, but causes a strong blue shift of the bonding modes, leading to an energetic rearrangement of the modes compared to those of a capacitively coupled dimer with similar dimensions.

We present the synthesis of Bi1–x Sb x nanowires with controlled composition between x = 0.05 and x = 0.40 over a wide range of diameters (20–100 nm) interesting for the investigation of the enhancement of thermoelectric efficiency via quantum size effects. We find that the relative concentration of Bi and Sb ions in the electrolyte, together with the deposition potential, determines the resulting nanowire composition. Morphology and composition were analyzed using X-ray diffraction, electron microscopy, and energy dispersive X-ray analysis. Two different templates were fabricated to enable the synthesis of nanowires with smooth and rough contour.

We report the fabrication of Bi 2 Te 3 nanowires with diameters as small as 15 nm, which is comparable to the size theoretically estimated for the onset of improvement of the thermoelectric figure of merit ZT by quantum-size effects. The versatility of the template-assisted growth, combining self-prepared ion-track etched membranes and electrochemical deposition, has been employed to synthesize Bi 2 Te 3 nanowires with controlled diameters in 10, 30, and 60 μm thick membranes and with large aspect ratios (length over diameter) of up to 1000. SEM, HRTEM, and XRD investigations reveal how morphology, surface roughness, and crystalline orientation of the Bi 2 Te 3 nanowires depend on deposition potential, temperature, and channel diameter.

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