We demonstrate that dodecanethiol monolayer passivation can significantly enhance the anode performance of germanium (Ge) nanowires in lithium-ion batteries. The dodecanethiol-passivated Ge nanowires exhibit an excellent electrochemical performance with a reversible specific capacity of 1130 mAh/g at 0.1 C rate after 100 cycles. The functionalized Ge nanowires show high-rate capability having charge and discharge capacities of ∼555 mAh/g at high rates of 11 C. The functionalized Ge nanowires also performed well at 55 °C, showing their thermal stability at high working temperatures. Moreover, full cells using a LiFePO(4) cathode were assembled and the electrodes still have stable capacity retention. An aluminum pouch type lithium cell was also assembled to provide larger current (∼30 mA) for uses on light-emitting-diodes (LEDs) and audio devices. Investigation of the role of organic monolayer coating showed that the wires formed a robust nanowire/PVDF network through strong C-F bonding so as to maintain structure integrity during the lithiation/delithiation process. Organic monolayer-coated Ge nanowires represent promising Ge-C anodes with controllable low carbon content (ca. 2-3 wt %) for high capacity, high-rate lithium-ion batteries and are readily compatible with the commercial slurry-coating process for cell fabrication.

A comprehensive mechanistic study conducted on the formation mechanism of five-fold twinned copper nanowires by heating copper(I) chloride with oleylamine at 170 °C is presented. Electron microscopy and UV-visible absorption spectra are used to analyze the growth mechanism of copper nanowires. High-resolution transmission electron microscopy and selected-area electron diffraction are used to investigate the detailed structure of copper nanowires and nanoparticles, and a five-twinned structure is shown to exist in the copper nanowires and nanoparticles. Additionally, experiments have been performed to indirectly confirm that oleylamine preferentially adsorbs on the {100} facets of growing crystals. On the basis of the above results, the self-seeded growth of copper nanowires is confirmed. In the initial stage of reactions, copper nanoparticles with two distinctive sizes are formed. As the reaction proceeds, larger five-twinned copper nanoparticles serve as seeds for anisotropic crystal growth. Further, copper atoms generated from an Ostwald ripening process or reduction reactions of a copper(I) chloride-oleylamine complex continue to deposit and crystallize on the twin boundaries. Once the {110} planes are generated, oleylamine preferentially adsorbs on the newly formed {100} facets and then guides the formation of nanowires. The electrical resistivity of a single copper nanowire is measured to be 41.25 nΩ-m, which is of the same order of magnitude as the value of bulk copper (16.78 nΩ-m). Finally, an effective surface-enhanced Raman spectroscopy active substrate made of copper nanowire is used to detect the 4-mercaptobenzoic acid molecules.

To explore spintronics applications for Ge nanowire heterostructures formed by thermal annealing, it is critical to develop a ferromagnetic germanide with high Curie temperature and take advantage of the high-quality interface between Ge and the formed ferromagnetic germanide. In this work, we report, for the first time, the formation and characterization of Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire transistors, in which the room-temperature ferromagnetic germanide was found through the solid-state reaction between a single-crystalline Ge nanowire and Mn contact pads upon thermal annealing. The atomically clean interface between Mn(5)Ge(3) and Ge with a relatively small lattice mismatch of 10.6% indicates that Mn(5)Ge(3) is a high-quality ferromagnetic contact to Ge. Temperature-dependent I-V measurements on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) nanowire heterostructure reveal a Schottky barrier height of 0.25 eV for the Mn(5)Ge(3) contact to p-type Ge. The Ge nanowire field-effect transistors built on the Mn(5)Ge(3)/Ge/Mn(5)Ge(3) heterostructure exhibit a high-performance p-type behavior with a current on/off ratio close to 10(5), and a hole mobility of 150-200 cm(2)/(V s). Temperature-dependent resistance of a fully germanided Mn(5)Ge(3) nanowire shows a clear transition behavior near the Curie temperature of Mn(5)Ge(3) at about 300 K. Our findings of the high-quality room-temperature ferromagnetic Mn(5)Ge(3) contact represent a promising step toward electrical spin injection into Ge nanowires and thus the realization of high-efficiency spintronic devices for room-temperature applications.

In comparison to the well-characterized bottom-up synthesis of Au and Ag nanomaterials, the synthesis of Cu nanocrystals with well-defined and controllable shapes is still in need of improvement. Among the many shapes, a cube covered by six {100} facets can be regarded as a standard model to study the surface properties of {100} facets. Herein, we have prepared monodisperse Cu nanoparticles having a slightly truncated cubic shape with an average edge length of 75.7 nm and a standard deviation of 3.87% by using CuCl as the precursor, oleylamine as the reaction solvent, and trioctylphosphine and octadecylamine as shape control agents. The as-prepared Cu nanocubes tend to self-assemble on transmission electron microscopy grids or silicon substrates. Electron microscopy and small-angle X-ray scattering reveal that the Cu nanocubes prefer to self-assemble into 2D or 3D rhombohedral structures (RS). Large-area dense-packed films (1.5 cm × 2.5 cm) composed of monodisperse Cu nanocubes were fabricated by immersing a Si substrate in a dispersion of dodecanethiol-capped Cu nanocubes in toluene and evaporating the toluene at a controlled rate while holding the substrate at an angle. The electrical properties of the Cu films with various thickness and annealing temperatures were studied.

Graphene oxide (GO) is a nanomaterial with burgeoning bioapplications, while autophagy is implicated in cancer therapy. Although induction of autophagy by nanomaterials is reported, the underlying signaling mechanism in cancer cells and how this implicates the potential of GO in cancer therapy remain obscure. Here, it is shown that GO itself can induce the toll-like receptors (TLRs) responses and autophagy in cancer cells and confer antitumor effects in mice. GO can be phagocytosed by CT26 colon cancer cells, simultaneously triggering autophagy as well as TLR-4 and TLR-9 signaling cascades. By dissecting the crosstalk between the TLRs and autophagy pathways, it is uncovered that the GO-activated autophagy is regulated through the myeloid differentiation primary response gene 88 (MyD88)- and TNF receptor-associated factor 6 (TRAF6)-associated TLR-4/9 signaling pathways. Injection of GO alone into immunocompetent mice bearing the CT26 colon tumors not only suppresses the tumor progression but also enhances cell death, autophagy, and immune responses within the tumor bed. These data altogether implicate the potential of GO as an effective nanomaterial for autophagy induction and cancer therapy.

In this study, we report on the formation of a single-crystalline Ni(2)Ge/Ge/Ni(2)Ge nanowire heterostructure and its field effect characteristics by controlled reaction between a supercritical fluid-liquid-solid (SFLS) synthesized Ge nanowire and Ni metal contacts. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies reveal a wide temperature range to convert the Ge nanowire to single-crystalline Ni(2)Ge by a thermal diffusion process. The maximum current density of the fully germanide Ni(2)Ge nanowires exceeds 3.5 × 10(7) A cm(-2), and the resistivity is about 88 μΩ cm. The in situ reaction examined by TEM shows atomically sharp interfaces for the Ni(2)Ge/Ge/Ni(2)Ge heterostructure. The interface epitaxial relationships are determined to be [Formula: see text] and [Formula: see text]. Back-gate field effect transistors (FETs) were also fabricated using this low resistivity Ni(2)Ge as source/drain contacts. Electrical measurements show a good p-type FET behavior with an on/off ratio over 10(3) and a one order of magnitude improvement in hole mobility from that of SFLS-synthesized Ge nanowire.

Solid and hollow structures of Cu 2−x Te nanocrystals are synthesized by the injection of a Te−TOP solution at different reaction times. Both types of Cu 2−x Te nanocrystals exhibit an intense absorption peak (localized surface plasmon resonance (LSPR)) in the near-infrared region, arising from excess holes in the valence band, and high molar extinction coefficients of 2.6 × 10 7 M −1 cm −1 at 1150 nm and 8.1 × 10 7 M −1 cm −1 at 1200 nm are demonstrated for the solid-type and hollow-type Cu 2−x Te nanocrystals, respectively. The experimentally observed extinction spectra and calculated extinction spectra based on the electrostatic approximation are studied. The LSPR responses in the near-infrared (NIR) region for both solid and hollow Cu 2−x Te nanocrystals are affected by the refractive index of the medium, whereas the NIR resonance shift is more obvious in the hollow-type Cu 2−x Te nanocrystals. Furthermore, the localized surface plasmon band of the Cu 2−x Te nanostructures can be tuned by post processing via oxidation and reduction methods (controlling their degree of copper deficiency).

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