Multidimensional Aligned Nanowires Array: Toward Bendable and Stretchable Strain Sensors

Micropatterns based on the oriented nanowires have attracted research interests for their unique physicochemical advantages in various applications of electric microdevices. Here, we proposed a facile fibrous dewetting strategy by spreading and dewetting of the silver nanowire (AgNW) solution on the vertical aligned carbon nanotube array (ACNTs) for preparing multidimensional aligned nanowires array, based on the elastocapillary coalescence. The unidirectional shrinking of the liquid film on the top of ACNTs happens during the dewetting process, as a result of the elastocapillary coalescence of ACNTs, which drives the AgNWs aligned along normal direction of liquid film shrinkage on the top of ACNTs. Thus, a multidimensional aligned NWs array was prepared, composing of the horizontally oriented NWs of top layer and vertical ACNT bundles of under layer connected by CNT yarns. A bendable flexible electrode was prepared using the as-prepared multidimensional aligned nanowires array, showing high stability during bending cycles (1800 cycles). Moreover, the multidimensional aligned nanowires array is also applicable for fabricating strain sensors, which show stable resistance response under strain. We envision that the as-developed approach shed new light on easy manufacture NW-based micropatterns.

Thermal Evaporation Synthesis of Vertically Aligned Zn2SnO4/ZnO Radial Heterostructured Nanowires Array

The construction of a heterostructured nanowires array allows the simultaneous manipulation of the interfacial, surface, charge transport, and transfer properties, offering new opportunities to achieve multi-functionality for various applications. Herein, we developed facile thermal evaporation and post-annealing method to synthesize ternary-Zn2SnO4/binary-ZnO radially heterostructured nanowires array (HNA). Vertically aligned ZnO nanowires array (3.5 μm in length) were grown on a ZnO-nanoparticle-seeded, fluorine-doped tin oxide substrate by a hydrothermal method. Subsequently, the amorphous layer consisting of Zn-Sn-O complex was uniformly deposited on the surface of the ZnO nanowires via the thermal evaporation of the Zn and Sn powder mixture in vacuum, followed by post-annealing at 550 °C in air to oxidize and crystallize the Zn2SnO4 shell layer. The use of a powder mixture composed of elemental Zn and Sn (rather than oxides and carbon mixture) as an evaporation source ensures high vapor pressure at a low temperature (e.g., 700 °C) during thermal evaporation. The morphology, microstructure, and charge-transport properties of the Zn2SnO4/ZnO HNA were investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. Notably, the optimally synthesized Zn2SnO4/ZnO HNA shows an intimate interface, high surface roughness, and superior charge-separation and -transport properties compared with the pristine ZnO nanowires array.

Reaction mechanism of copper azide nanowires array

In-situ growth of copper azide has endowed this highly sensitive primary explosive new life, but its mechanism study is not enough to support its in-depth study. Hence, azidation reaction was conducted on highly ordered copper nanowires array, which could provide effective channels for gas phase reactant (hydrazoic acid, HN3) to penetrate the solid, further study the mechanism of azidation reaction on copper azide nanowires array, and clarify the relationship between the microstructure and its azidation degree. Gas–solid in-situ azidation technique was used for this in-depth study. The effects of reaction temperature on formation of gaseous HN3 were studied by isothermal thermogravimetry. The azidation results were analyzed by SEM and XRD, the effects of the reaction time, diameter of copper nanowires array precursor and oxidation degree on the azidation degree were studied in detail. This work not only provided deep investigation on the azidation process, but also offered effective guidance for the synthesis of copper azide nanowires array.