Vapor–Liquid–Solid Growth of Endotaxial Semiconductor Nanowires

Free-standing and in-plane lateral nanowires (NWs) grown by the vapor–liquid–solid (VLS) process have been widely reported. Herein, we demonstrate that the VLS method can be extended to the synthesis of horizontally aligned semiconductor NWs embedded in substrates. Endotaxial SiGe NWs were grown in silicon substrates by tuning the directional movement of the catalyst in the substrates. The location of the SiGe NWs can be controlled by the SiO₂ pattern on the silicon surface. By varying the growth conditions, the proportion of Ge in the obtained NWs can also be tuned. This approach opens up an opportunity for the spatial control of the NW growth in substrates and can potentially broaden the applications of NWs in new advanced fields

Nickel Cobalt Oxide-Single Wall Carbon Nanotube Composite Material for Superior Cycling Stability and High-Performance Supercapacitor Application

The electron conductivity of electrode material has always been a problem that hinders the practical application of supercapacitor. In this contribution, we report a facile synthesis of highly conductive nickel cobalt oxide-single wall carbon nanotube (NiCo₂O₄–SWCNT) nanocomposite by controlled hydrolysis process in ethanol–water mixed solvent. Ultrafine NiCo₂O₄ nanocrystals with a diameter around 6–10 nm are formed on the functionalized SWCNT bundles. This novel material not only exhibits a high specific capacitance of 1642 F g^–1 within a 0.45 V potential range but also shows an excellent cycling stability of 94.1% retention after 2000 cycles at high mass loading. Our method provides a promising facile and high-performance strategy for supercapacitor electrode application

Forest of Gold Nanowires: A New Type of Nanocrystal Growth

We report a nanowire growth that is highly unconventional: (1) nanowires can grow from substrate-bound seeds but cannot from colloidal seeds under otherwise the same conditions; (2) the nanowires grow from only one side of the seeds, with their diameter independent of the size of the seeds; and (3) vertically aligned ultrathin nanowires are obtained on substrates, using aqueous solution and ambient conditions. With carefully designed experiments, we propose and test a new mechanism that can explain these unusual phenonmena. It turns out that the strong binding of ligands in this system forces selective deposition of Au at the ligand-deficient interface between Au seeds and oxide substrates. This means of promoting anisotropic growth of nanocrystals into nanowires is previously unknown in the literature. We are able to pinpoint the site of active growth and explain the control of nanowire width. The sustained growth at the active site and the inhibited growth at its parameter push the nanocrystals upward into wires; their diameter is dependent on the dynamic competition of the two processes. The site-specific growth from substrate-anchored seeds provides a rare means to create substrate-nanowire hierarchical structures in aqueous solution under ambient conditions. Rendering a surface conductive, particularly one with complex surface morphology, is now made easy

High-Density 3D-Boron Nitride and 3D-Graphene for High-Performance Nano–Thermal Interface Material

Compression studies on three-dimensional foam-like graphene and h-BN (3D-C and 3D-BN) revealed their high cross-plane thermal conductivity (62–86 W m^–1 K^–1) and excellent surface conformity, characteristics essential for thermal management needs. Comparative studies to state-of-the-art materials and other materials currently under research for heat dissipation revealed 3D-foam’s improved performance (20–30% improved cooling, temperature decrease by Δ<i>T</i> of 44–24 °C)