We report the fabrication of vertically aligned NiO nanowalls on nickel foils using a plasma assisted oxidation method. Electrochemical properties of as-synthesized NiO nanowalls were evaluated by galvanostatic cycling and cyclic voltammetery. The results show a capacity of ∼638 (mA h)/g (at 1.25C rate), with excellent capacity retention of up to 85 cycles, when cycled in the range, 0.005−3.0 V vs Li. The superior electrochemical performance of NiO nanowalls in comparison to the previously reported results on nanosized NiO particles can be attributed to its large surface area and shorter diffusion length for mass and charge transport. A possible reaction mechanism is discussed. We also report that electron field emission studies show that the verticllay aligned NiO nanowalls are efficient field emitters with a turn-on field of 7.4 V/µm and a maximum current density of ∼160 µA/cm2 can be achieved.

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We report an efficient method to synthesize vertically aligned Co3O4 nanostructures on the surface of cobalt foils. This synthesis is accomplished by simply heating the cobalt foils in the presence of oxygen gas. The resultant morphologies of the nanostructures can be tailored to be either one‐dimensional nanowires or two‐dimensional nanowalls by controlling the reactivity and the diffusion rate of the oxygen species during the growth process. A possible growth mechanism governing the formation of such nanostructures is discussed. The field‐emission properties of the as‐synthesized nanostructures are investigated in detail. The turn‐on field was determined to be 6.4 and 7.7 V μm–1 for nanowires and nanowalls, respectively. The nanowire samples show superior field‐emission characteristics with a lower turn‐on field and higher current density because of their sharp tip geometry and high aspect ratio.

Our thermal memory device consists of three basic segments: an input terminal ( T in ), an output terminal ( T out ), and a heat conduction channel bridging the two. The two terminals are suspended with suspension leads connected to the substrate ( T base ) (Figure 1 a). To explore the thermal memory effect, we used a single-crystalline suspended VO 2 nanobeam, which undergoes MIT from a low-temperature insulating (I) phase to a high-temperature metallic (M) phase around 340 K, [ 7 ] as a An Electrically Tuned Solid-State Thermal Memory Based on Metal-Insulator Transition of Single-Crystalline VO 2 Nanobeams A solid-state thermal memory that can store and retain thermal information with temperature states as input and output is demonstrated experimentally. A single-crystal VO 2 nanobeam is used, undergoing a metal-insulator transition at ∼ 340 K, to obtain a nonlinear and hysteresis response in temperature. It is shown that the application of a voltage bias can substantially tune the characteristics of the thermal memory, to an extent that the heat conduction can be increased ∼ 60%, and the output HIGH/LOW temperature difference can be amplifi ed over two orders of magnitude compared to an unbiased device. The realization of a solid-state thermal memory combined with an effective electrical control thus allows the development of practical thermal devices for nano-to macroscale thermal management.

We report a catalyst free method to synthesize single crystal quality Nb 2 O 5 nanowire arrays. Vertically oriented Nb 2 O 5 nanowires directly on Nb foils were synthesized by a thermal oxidation method. The electron field emission (FE) properties of the as-synthesized Nb 2 O 5 nanowires were investigated in detail. Our results showed that the Nb 2 O 5 nanowires are excellent FE emitters with fairly low turn on and threshold field. A remarkably high current density of ∼4 mA/cm 2 was achieved at an applied field of 11 V/µm. At moderate applied fields, a continuous and uniform electron emission can be acquired from the Nb 2 O 5 nanowire emitters for a total testing time of 10 h without any noticeable diminution.

Crystalline Mn doped ZnO nanowires were synthesized by chemical vapour deposition. The presence of Mn dopant was confirmed by X-Ray diffraction, Raman spectroscopy, transmission electron microscopy and X-Ray photoelectron spectroscopy. The photoconductivity of an individual Mn doped ZnO nanowire was investigated under different visible light excitations (532 and 405 nm). The nanowire exhibited high dark to photocurrent ratios ($50), fast photocurrent response ($100-250 ms), and reasonably high responsivity and external quantum efficiencies with good repeatability under different visible light illuminations. These results indicate that Mn doped ZnO nanowires would be promising for efficient multispectral photodetectors and optical switches.

We report a simple and effective approach to organize micron- and submicron-sized particles in a size selective manner. This approach utilizes the template assisted directed self-assembly technique. A topographically patterned photoresist surface is fabricated and used to create an ordered array of colloidal particles from their aqueous suspensions. Assembly of particles on this template is then achieved by using a conventional spin coating technique. Feasibility of this technique to form a large area of patterned particle assemblies has been investigated. To arrange the particles on the template, the physical confinement offered by the surface topography must overcome a joint effect of centrifugal force and the hydrophobic nature of the photoresist surface. This concept has been extended to the size selective sorting of colloidal particles. The capability of this technique for sorting and organizing colloidal particles of a particular diameter from a mixture of microspheres is demonstrated.

We present a comprehensive approach to address the correlation between mechanical properties of nanowires (NWs) with their characteristic size, microstructure, and chemical composition. Using this technique, the Young's modulus of Co3O4 NWs with different sizes was evaluated. Thermal annealing in inert atmosphere was found to induce chemical reduction of as-grown Co3O4 NWs into CoO NWs without modifying their geometrical shape. Both Co3O4 and CoO NWs exhibited a size-dependent variation in Young's modulus.