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A size effect of more scattered strength with decreasing diameter is revealed by tension experiments on melt-spinning fabricated Pd77.5Cu6Si16.5 metallic glass microwires, and is explained from a perspective of structural inhomogeneity and a higher structure sensitivity of metallic glasses under tension condition and in a large aspect ratio. Such a result differs from the understanding of “the smaller the stronger” in the compression behaviors of metallic glasses, but indicates that the shear bands in metallic glasses actually could nucleate in a wide stress range. This finding could provide experimental evidence for the inhomogeneous structure and size effect in metallic glasses at the micro-scale, and could help the further study of their mechanical behaviors and substantial deformation mechanism.

Household light bulbs made from macroscopic single-walled and double-walled carbon nanotube filaments were fabricated and tested. The nanotube bulbs are found to possess several interesting features when compared to a conventional tungsten filament in safelight (36 V, 40 W), such as lower threshold voltage for light emission and higher brightness at high voltages. Electrically induced excited peaks at 407, 417, 655 nm were identified to be an intrinsic property of nanotubes and these peaks are observed to become stronger in the light emission spectra at high temperatures which cannot be explained easily with the concept of blackbody emission.

We explore the transport properties of mixed ionic-electronic conductors made of carbon nanotube/RbAg4I5 film composite nanostructures in the presence of optical fields. The formation of ion-electron bound states (IEBSs) due to Coulomb interactions results in significant conductance decrease. The wavelength-dependent and power-dependent dynamic responses show that the effect of photo-induced dissociation of IEBSs is pronounced in the visible region and negligible in near-infrared region. Our results lead to a deeper understanding of the impact of ion-electron interactions (IEIs) on transport and are expected to open up a way for designing new-type photodetectors based on IEIs.

We have explored the ion-modulated electronic transport properties of mixed ionic-electronic conductor (MIEC) composite nanostructures made of superionic conductor RbAg4I5 films and carbon nanotube (CNT) bundle spiderwebs. Our experimental and theoretical studies indicate that the formation of ion-electron bound states (IEBSs) leads to strong ion-electron interference effect and interesting electronic transport of CNT, such as nonlinear current-voltage (I–V) characteristics and novel temperature dependence of the current. With increasing temperature, the hybrid nanostructures show rich phases with different dependence of current on temperature, which is related to the structural phase transition of RbAg4I5 and the transition of dissociation of IEBSs. The ion-modulation of the electric conductivity in such MIEC composite nanostructures with great tunability has been used to design new ionic-electronic composite nano-devices with function like field effect transistor.

Very less attention has been paid recently to the electrochemical properties of graphene films with intrinsic flat structure prepared by chemical vapor deposition (CVD). In this work, button supercapacitors were fabricated using ionic liquid as electrolytes and layer-by-layer graphene structures as electrodes. The specific capacitances of the supercapacitors increased with the increase of layer number. The areal specific capacitance of ten-layer graphene supercapacitor was 0.29 mF/cm2 at the scan rate of 50 mV/s, which was about three times of that of monolayer graphene supercapacitor (0.1 mF/cm2). The sandwiched multi-layer structures with oxide deposition further improved the device performance. However, the polycrystalline nature of CVD-grown graphene films introduced structural instability during charge-discharge process, resulting in degraded capacitive performance and cycling stability. Our results suggest that graphene films with intrinsic “in-plane” structure might not be ideal candidates for electrode materials.

Graphene woven fabric (GWF) prepared from chemical vapor deposition was used as smart self-sensing element to assemble piezoresistor through directly transferring onto the flexible substrate poly(dimethylsiloxane) (PDMS) with the deposited Ti/Au electrodes. A rational strategy was proposed to fabricate flexible touch sensors easily and effectively with the full usage of the mechanical and electrical properties of GWF, whose resistance is highly sensitive to macro-deformation or micro-defect. Compared to commercial and traditional touch sensing, the GWF-on-PDMS piezoresistor is structurally flexible that is demanded under special conditions and meanwhile makes the piezoresistor to have excellent durability.

We study the influence of gas absorption on the photovoltaic properties of carbon nanotube/Si solar cells (CSSCs). The power efficiency of CSSCs changes evidently when exposed in gas, resulting from the resistance change of carbon nanotube (CNT) by gas absorption. The performances of CSSCs degrade when they are long time exposed in air, which results mainly from excessive gas absorption. Gas desorption on CNTs is accelerated by applying a current through the cells, making recovery of efficiency. By applying a current through the cells before light illumination, CSSCs show stable efficiency at ∼10% in one month.

A T-type method is developed to comprehensively evaluate the thermoelectric properties of materials. The thermoelectric properties, including thermal conductivity, thermopower, and electrical conductivity of an ultralong double-walled carbon nanotube bundle are studied from 240 K to 340 K by applying the T-type method. The determined figure of merit achieves 10−3 which is significantly larger than that reported for carbon nanotubes samples. The bundle consists of thousands of nanotubes aligned along the long axis with low levels of impurities, and the thermal conductivity is significantly reduced compared to that of individual double-walled nanotube, while the electrical conductivity is superior to most of the carbon nanotubes samples.

We explore the photoconductive properties of double-walled carbon nanotube film under laser illumination at different wavelengths in both ambient air and vacuum. In our experimental measurements, the photoconductivity of the film shows a strong dependence on the wavelength of light and can be changed from negative to positive by fully removing oxygen. We propose that competition among photoexcitation, photodesorption, and surface plasmon polaritons is responsible for these interesting phenomena. Our results are expected to provide potential applications in the field of nano-optoelectronic sensors based on carbon nanotubes.

Photoinduced molecular desorption from solid surfaces will modify the electrical transporting properties of matter and result in significant change in resistance. The UV induced resistive response of graphene films prepared by chemical vapor deposition was investigated. The resistance of graphene increased exponentially upon UV irradiation and decreased also in an exponential form when the UV light was turned off. Both processes exhibited large time constants of hundreds of seconds. UV-induced molecular desorption mechanisms for graphene, carbon nanotubes, and reduced graphene oxides were compared and discussed.

Hetrodimensional contacts were fabricated by coating double-walled carbon nanotube (CNT) films on CuO nanowire arrays. Wavelength dependent photovoltaic effects by irradiating the devices with 405, 532, and 1064 nm lasers were observed. Two possible mechanisms responsible for the observed results were discussed. Photoexcitations within CuO nanowires and Schottky barriers in the heterojunctions dominate the photovoltaics in the 405 and 532 nm cases. For the 1064 nm case, the photovoltaic is the result of the excitation within the CNTs and of the heterodimensionality effect. Control experiments on CNT film/CuO granular film hetrodimensional contacts further show the relationship between these two mechanisms.

A structure for visible photosensors based on double-walled carbon nanotube (DWCNT) film/Cu2O nanoparticle (NP) film/TiO2 nanotube array (TNA) heterojunctions has been fabricated. Cu2O nanoparticles reduce dark current and enhance photoresponse of the heterojunctions. Consequently, the optoelectric performance is significantly enhanced compared to that of the heterojunctions without Cu2O nanoparticles. The photocurrent-to-dark current ratio reaches ∼1 × 104 under illumination at 405 nm and ∼3 × 104 under illumination at 532 nm, which is two orders of magnitude higher than the results of double-walled carbon nanotube film/TiO2 nanotube array heterojunctions under the same illumination density. Moreover, the response speed of the heterojunctions is greatly improved.

The existence of surface steps was found to have significant function and influence on the growth of graphene on copper via chemical vapor deposition. The two typical growth modes involved were found to be influenced by the step morphologies on copper surface, which led to our proposed step driven competitive growth mechanism. We also discovered a protective role of graphene in preserving steps on copper surface. Our results showed that wide and high steps promoted epitaxial growth and yielded multilayer graphene domains with regular shape, while dense and low steps favored self-limited growth and led to large-area monolayer graphene films. We have demonstrated that controllable growth of graphene domains of specific shape and large-area continuous graphene films are feasible.

We report a metal-insulator-semiconductor heterojunction solar cell by depositing a carbon nanotube film onto silicon substrate, followed by acid oxidation of the Si surface to form a thin oxide layer at the junction interface. The nanotube-oxide-Si solar cells with polymer encapsulation show stable efficiencies of above 10%, owing to enhanced photon absorption, inhibited charge recombination, and reduced internal resistance. Parallel and series connections without sacrificing cell efficiencies were demonstrated.

Thin-walled carbon nanotubes (CNTs) filled with different ferromagnetic alloy (FeCo, FeNi, and FeCoNi) nanowires were prepared by using trichlorobenzene as carbon precursor. They were dispersed into epoxy resin and then coated onto 180×180 mm2 aluminum substrates to form microwave-absorption coatings with 2.0 mm thickness. Reflection loss exceeding −5 dB was obtained between 5 and 18 GHz for coating containing 1.3 wt % FeCo-filled CNTs. A minimum reflection loss value of −28.2 dB was achieved at 15.2 GHz in FeCoNi-filled CNTs/epoxy coating. The areal densities of coatings are only 2.35 kg/m2, which is favorable for the applications requiring low density.

The metallic state and resistivity of interconnected double-walled carbon nanotube bundles have been tuned by modifying two major components, including (1) structure of the bundles and (2) contacts at the heterojunctions between the bundles. Infrared laser illumination at controlled intensity on the nanotubes produces an amorphous carbon coating that subsequently serves as the solder material to weld the bundles at their heterojunction sites. The results show that without selective etching of metallic or semiconductor species, the crossover temperature at which metallic behavior changes to semiconducting can be tuned within a wide range (25–150K).

The relative efficacy of electric lamps with double-walled carbon nanotube (DWNT) filaments is higher than that with tungsten filaments at the same input power. The luminescence of DWNT electric lamps shows a cold light performance besides blackbody radiation. At a color temperature of 2386 K, the visible light emitted by the DWNT electric lamp (filament diameter: 0.06 mm) occupies 7.6% of the total radiation energy, higher than that of tungsten lamps. The longevity of the DWNT electric lamp (filament diameter: 0.15 mm, 15 V) is no less than 3000 h. DWNT electric lamps are energy saving at low voltages and have potential applications.

Significant photoinduced currents have been explored in carbon nanotube/metal heterojunctions, i.e., heterodimension junctions containing macrolong carbon nanotubes (CNTs). The experimental measurements clearly show that the net transport direction of the photoexcited electrons is from the lower dimensional CNTs to higher dimensional CNTs or metal electrodes and the photoinduced currents dramatically depend on the laser spot position relative to the junction interface. The currents increase linearly with the increase of the laser intensity as the intensity is not very large. A prototype sensor has been constructed to illustrate applications of the heterodimension junctions in photoelectronics.