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• The capacities achieved 0.08 mAh/cm2 for thin-film electrolytic MnO 2 -Zn batteries. • Over 200 cycles were demonstrated for batteries with electrolyte of 25 µL/cm2. • The shuttle reactions caused by iodide mediators were revealed experimentally. Whilst electrolytic MnO 2 with a high capacity draws great attention recently, the shuttle reactions between the mediator additives in the electrolytes with zinc and MnO 2 are often overlooked. In this work, neutral acetate electrolytes with iodide mediator are tested for electrolytic MnO 2 -Zn system on thin-film batteries. With a limited amount of electrolyte, the shuttle reactions caused by iodide mediator becomes more obvious, which results in low Coulombic efficiencies and shortens shelf-life. [ABSTRACT FROM AUTHOR]

We report on the improvement of power conversion efficiency (PCE) of PTB7/PC70BM solar cells by the addition of small quantities (0.02%-0.04%) of pristine single-walled carbon nanotubes (SWNTs) in the active-layer. SWNTs and purified semiconducting SWNTs (S-SWNTs) were added in quantities, which is 2 orders of magnitude lower than previously reported value and resulted in a reduction in the series resistance of the solar cell with minor changes on the shunt resistance. On addition of purified S-SWNT, the PCE of air measured devices enhanced by 29% from 4.9% to 6.3%, with short-circuit current density (JSC) improving from 12.1mA/cm² to 14.4 mA/cm² and a fill factor improvement from 54% to 61%. In addition, the role of processing additive N-Methyl-2-pyrrolidone, which acts as a SWNT dispersant, is also investigated. A single diode model of a solar cell is used to extract the cell parameters and understand the effect of SWNTs. Based on experimental data and it's fitting to the single diode model, we propose that S-SWNT improve the transport and extraction of photogenerated charges within the solar cell device. [ABSTRACT FROM AUTHOR]

The possibility of enhancing the frequency performance of electrochemical capacitors by tailoring the nanostructure of the carbon electrode to increase electrolyte permeability is demonstrated. Highly porous, vertically oriented carbon electrodes which are in direct electrical contact with themetallic current collector are produced viaMPECVD growth onmetal foils.Theresulting structure has a capacitance and frequency performance between that of an electrolytic capacitor and an electrochemical capacitor. Fully packaged devices are produced on Ni and Cu current collectors and performance compared to state-of-the-art electrochemical capacitors and electrolytic capacitors.The extension of capacitive behavior to the AC regime (~100Hz) opens up an avenue for a number of new applications where physical volume of the capacitor may be significantly reduced. [ABSTRACT FROM AUTHOR]

Herein we present an inexpensive facile wet-chemistry-free approach to the transfer of chemical vapour-deposited multiwalled carbon nanotubes to flexible transparent polymer substrates in a single-step process. By controlling the nanotube length, we demonstrate accurate control over the electrical conductivity and optical transparency of the transferred thin films. Uniaxial strains of up to 140% induced only minor reductions in sample conductivity, opening up a number of applications in stretchable electronics. Nanotube alignment offers enhanced functionality for applications such as polarisation selective electrodes and flexible supercapacitor substrates. A capacitance of 17 F/g was determined for supercapacitors fabricated fromthe reported dry-transferred MWCNTs with the corresponding cyclic voltagrams showing a clear dependence on nanotube length [ABSTRACT FROM AUTHOR]

Abstract: We report on a facile low temperature method for the preparation of high surface area, nanostructured α-Fe2O3 (hematite) thin films and their application as photoelectrochemical (PEC) water splitting electrodes. The hematite films are fabricated by thermal oxidation in air of DC sputter deposited iron films at temperatures as low as 255°C. This method results in films with a higher surface area than typically obtained by directly sputtering α-Fe2O3. It is shown that beyond a minimum iron thickness, α-Fe2O3 nanowires result upon thermal treatment in atmospheric conditions. Structural and optical characteristics of the resulting films are analyzed. The oxidation process is studied in detail and correlated to the photoelectrical properties. The Fe films oxidize in stages via Fe-oxide layers of increasing oxidation states. Resulting photoelectrochemical performance of fully oxidized films is a balance between optical absorption and charge collection, which varies with film thickness. The optimum film achieved a net photocurrent density of 0.18mA/cm2 in 1M NaOH at 1.23V vs. RHE under simulated AM1.5 sunlight, amongst the highest values reported for undoped hematite films produced at low temperature. [Copyright &y& Elsevier]

We propose an electrode-free zinc manganese battery, where both zinc and MnO2 are electro-deposited from the electrolyte via a charging process onto carbon current collectors. The electrode-free batteries show an improved cycling performance of thin-film batteries than the ones with a zinc anode and a facilitated fabrication process for fiber batteries. [ABSTRACT FROM AUTHOR]

Linear wave energy converters generate intrinsically intermittent power with variable frequency and amplitude. A composite energy storage system consisting of batteries and super capacitors has been developed and controlled by buck-boost converters. The purpose of the composite energy storage system is to handle the fluctuations and intermittent characteristics of the renewable source, and hence provide a steady output power. Linear wave energy converters working in conjunction with a system composed of various energy storage devices, is considered as a microsystem, which can function in a stand-alone or a grid connected mode. Simulation results have shown that by applying a boost H-bridge and a composite energy storage system more power could be extracted from linear wave energy converters. Simulation results have shown that the super capacitors charge and discharge often to handle the frequent power fluctuations, and the batteries charge and discharge slowly for handling the intermittent power of wave energy converters. Hardware systems have been constructed to control the linear wave energy converter and the composite energy storage system. The performance of the composite energy storage system has been verified in experiments by using electronics-based wave energy emulators. [ABSTRACT FROM AUTHOR]

As a result of their morphology, nanowires bring new properties and the promise of performance for a range of electronic devices. This review looks into the properties of nanowires and the multiple ways in which they have been exploited for energy generation, from photovoltaics to piezoelectric generators. [ABSTRACT FROM AUTHOR]

In this paper, we present experimental results describing enhanced readout of the vibratory response of a doubly clamped zinc oxide (ZnO) nanowire employing a purely electrical actuation and detection scheme. The measured response suggests that the piezoelectric and semiconducting properties of ZnO effectively enhance the motional current for electromechanical transduction. For a doubly clamped ZnO nanowire resonator with radius ∼10 nm and length ∼1.91 µm, a resonant frequency around 21.4 MHz is observed with a quality factor (Q) of ∼358 in vacuum. A comparison with the Q obtained in air (∼242) shows that these nano-scale devices may be operated in fluid as viscous damping is less significant at these length scales. Additionally, the suspended nanowire bridges show field effect transistor (FET) characteristics when the underlying silicon substrate is used as a gate electrode or using a lithographically patterned in-plane gate electrode. Moreover, the Young's modulus of ZnO nanowires is extracted from a static bending test performed on a nanowire cantilever using an AFM and the value is compared to that obtained from resonant frequency measurements of electrically addressed clamped-clamped beam nanowire resonators. [ABSTRACT FROM AUTHOR]

Manganese oxide (MnO 2) is proven to be an efficient cathode material in zinc-ion batteries (ZIBs). However, its poor electronic conductivity strongly limits the performance of Zn–MnO 2 batteries. In order to improve performance beyond typical graphitic carbon additives, a binary conductive additive, a combination of carbon nanohorns (CNHs) and carbon nanotubes (CNTs), is added into the MnO 2 electrode to establish high-speed electron-channels in the CNTs/CNHs network with an efficient "line-to-surface-to-point" microstructure. In this electrode, the high aspect-ratio CNTs create a conducting highway for the collected charges, while the CNHs provide extra surface area for electron transfer. Moreover, the specific surface area of the electrode increases due to the introduction of CNHs, which increases the Zn2+ diffusion coefficient. As a result, the corresponding battery reaches a high specific capacity (343 mAh g−1 at 0.3 A g−1), excellent rate performance (191.3 mAh g−1 at 3 A g−1) and long-life cycle. Moreover, it achieves an admirable specific energy density of 466 W h kg−1, together with a peak power density of 9.4 kW kg−1 (normalized to the weight of MnO 2), the performance of which is among the best reported ZIBs. This work reveals new pathways to improve the performance of MnO 2 cathodes for ZIBs. Image 1 [ABSTRACT FROM AUTHOR]

Highly transparent zinc oxide (ZnO) nanowire networks have been used as the active material in thin film transistors (TFTs) and complementary inverter devices. A systematic study on a range of networks of variable density and TFT channel length was performed. ZnO nanowire networks provide a less lithographically intense alternative to individual nanowire devices, are always semiconducting, and yield significantly higher mobilites than those achieved from currently used amorphous Si and organic TFTs. These results suggest that ZnO nanowire networks could be ideal for inexpensive large area electronics. [ABSTRACT FROM AUTHOR]

A dielectric nanocomposite based oncyanoethylatedcellulose (CRS) and MMT nanoclay was successfully prepared with different weight percentages (5%, 10% and 15%) of MMT. MMT nanoplatets obtained via sonication of MMT nanoclay in acetone for a prolonged period was used in the preparation of CRS-MMT nanocomposites. CRS-MMT thin films on SiO 2 /Si wafers are used to form metal-insulator-metal (MIM) type capacitors. At 1 kHz CRS-MMT nanocomposites exhibited high dielectric constants (ε r ) of 71, 55 and 42 with low leakage current densities (10 −6 –10 −7 A/cm 2 ) for nanocomposites with 5%, 10% and 15% weight of MMT respectively, higher than values of pure CRS (21), Na-MMT(10). Reduction of ε r with higher MMT loading can be attributed to a network formation as evidenced via strong bonding interactions between CRS and MMT leading to a lower molecular mobility. The leakage is studied using conductive atomic force microscopy (C-AFM) indicates that leakage pathways are associated with MMT nanoplatelets embedded in the CRS polymer matrix. [ABSTRACT FROM AUTHOR]

We present a stable inkjet printable graphene ink, formulated in isopropyl alcohol via liquid phase exfoliation of chemically pristine graphite with a polymer stabilizer. The rheology and low deposition temperature of the ink allow uniform printing. We use the graphene ink to fabricate counter electrodes (CE) for natural and ruthenium-based dye-sensitized solar cells (DSSCs). The repeatability of the printing process for the CEs is demonstrated through an array of inkjet-printed graphene electrodes, with ∼5% standard deviation in the sheet resistance. As photosensitizers, we investigate natural tropical dye extracts from Pennisetum glaucum , Hibiscus sabdariffa and Caesalpinia pulcherrima . Among the three natural dyes, we find extracts from C . pulcherrima exhibit the best performance, with ∼0.9% conversion efficiency using a printed graphene CE and a comparable ∼1.1% efficiency using a platinum (Pt) CE. When used with N719 dye, the inkjet-printed graphene CE shows a ∼3.0% conversion efficiency, compared to ∼4.4% obtained using Pt CEs. Our results show that inkjet printable graphene inks, without any chemical functionalization, offers a flexible and scalable fabrication route, with a material cost of only ∼2.7% of the equivalent solution processed Pt-based electrodes. [ABSTRACT FROM AUTHOR]

• The CNTs/CNHs binary conductive additives design strategy is proposed. • The CNTs/CNHs modified LDH electrode exhibits superior electrochemical performance. • The synergistic mechanism between CNTs/CNHs and LDH are revealed. • The LDH@CNTs/CNHs//Activated carbon hybrid supercapacitor are assembled. Progress toward the development of advanced supercapacitor technologies is closely associated with high-performance electrode materials. Carbon-based conductive additives modifying electrode material effectively improves the electronic conductivity and promotes the redox reaction. In this paper, we developed a highly effective binary conductive additive to modify cobalt aluminum layered double hydroxide (CoAl LDH) electrode with superior electrochemical performance, where the binary carbon species included carbon nanotubes (CNTs) and carbon nanohorns (CNHs). The as-constructed binary conductive additives CNTs/CNHs present a highly efficient electronic transmission network via a "line to the surface to point" mode. The as-prepared CoAl LDH@CNTs/CNHs electrode exhibits a significantly enhanced specific capacitance, superior rate capability, and stable cycle life. Based on analyzing and studying the characterizations and simulation, we reveal the electron transport mechanism and synergistic effects between CNTs/CNHs and CoAl LDH in a new perspective. The assembled hybrid supercapacitor device exhibits a high energy density (62.2 Wh/kg) and good cycling ability (79% retention after 5500 cycles). We believe that the binary conductive additives design strategy presented here is expected to apply to other energy storage such as batteries and pseudocapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we report on the synthesis and applications of semiconducting nanostructures. Nanostructures of interest were zinc oxide (ZnO) nanowires and tungsten disulfide (WS2) nanotubes where transistors/phototransistors and photo-voltaic (PV) energy conversion cells have been fabricated. ZnO nanowires were grown with both high- and low-temperature approaches, depending on the application. Individual ZnO nanowire side-gated transistors revealed excellent performance with a field- effect mobility of 928 cm² /V · s. ZnO networks were proposed for large-area macroelectronic devices as a less lithographically intense alternative to individual nanowire transistors where mobility values in excess of 20 cm² /V · s have been achieved. Flexible PV devices utilizing ZnO nanowires as electron acceptors and for photoinduced charge separation and transport have been presented. Phototransistors were fabricated using individual WS2 nanotubes, where clear sensitivity to visible light has been observed. The results presented here simply reveal the potential use of inorganic nanowires/tubes for various optoelectronic devices. [ABSTRACT FROM AUTHOR]

This paper reports on the synthesis of zinc oxide (ZnO nanostructures and examines the performance of nanocomposite thin-film transistors (TFTs fabricated using ZnO dispersed in both n- and p-type polymer host matrices. The ZnO nanostructures considered here comprise nanowires and tetrapods and were synthesized using vapor phase deposition techniques involving the carbothermal reduction of solid-phase zinc-containing compounds. Measurement results of nanocomposite TFTs based on dispersion of ZnO nanorods in an n-type organic semiconductor ([6, 6]-phenvl-C61-butyric acid methyl ester) show electron field-effect mobilities in the range 03-0.6 cm²V-1s-1, representing an approximate enhancement by as much as a factor of 40 from the pristine state. The on/off current ratio of the nanocomposite TFTs approach 106 at saturation with off-currents on the order of 10 pA. The results presented here, although preliminary, show a highly promising enhancement for realization of high-performance solution-processable n-type organic TFTs. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanowires (NWs) grown on carbon fibers using a vapor transport and condensation approach are used as the cathode of a photoelectrochemical cell. The carbon fibers were obtained by electrospray deposition and take the form of a flexible carbon fabric. The ZnO NW on carbon fiber anode is combined with a “black dye” photoabsorber, an electrolyte, and a platinum (Pt) counterelectrode to complete the cell. The results show that ZnO NW and carbon fibers can be used for photoinduced charge separation/charge transport and current collection, respectively, in a photoelectrochemical cell. [ABSTRACT FROM AUTHOR]

The article presents a correction to the paper "Zinc Oxide Nanostructures and High Electron Mobility Nanocomposite Thin Film Transistors," by Flora M. Li, Gen-Wen Hsieh, Sharvari Dalal, et al., from the November 2008 issue.