Abstract: By use of the membrane-templated synthesis route, hydrous RuO2 (RuO2·xH2O) nanotubular arrayed electrodes were successfully synthesized by means of the anodic deposition technique. The desired three-dimensional mesoporous architecture of RuO2·xH2O nanotubular arrayed electrodes with annealing in air at 200 °C for 2 h simultaneously maintained the facility of electrolyte penetration, the ease of proton exchange/diffusion, and the metallic conductivity of crystalline RuO2, exhibiting unexpectedly ultrahigh power characteristics with its frequency “knee” reaching ca. 4.0−7.8 kHz, 20−40 times better than that of RuO2 single crystalline, arrayed nanorods. The specific power and specific energy of annealed RuO2·xH2O nanotubes measured at 0.8 V and 4 kHz is equal to 4320 kW kg-1 and 7.5 W h kg-1, respectively, demonstrating the characteristics of next generation supercapacitors.

Abstract: Extensive efforts to develop a solid-oxide fuel cell for transportation, the bottoming cycle of a power plant, and distributed generation of electric energy are motivated by a need for greater fuel efficiency and reduced air pollution. Barriers to the introduction of hydrogen as the fuel have stimulated interest in developing an anode material that can be used with natural gas under operating temperatures 650 degrees C < T < 1000 degrees C. Here we report identification of the double perovskites Sr2Mg(1-x)MnxMoO(6-delta) that meet the requirements for long-term stability with tolerance to sulfur and show a superior single-cell performance in hydrogen and methane.

Abstract: The drive towards increased energy efficiency and reduced air pollution has led to accelerated worldwide development of fuel cells. As the performance and cost of fuel cells have improved, the materials comprising them have become increasingly sophisticated, both in composition and microstructure. In particular, state-of-the-art fuel-cell electrodes typically have a complex micro/nano-structure involving interconnected electronically and ionically conducting phases, gas-phase porosity, and catalytically active surfaces. Determining this microstructure is a critical, yet usually missing, link between materials properties/processing and electrode performance. Current methods of microstructural analysis, such as scanning electron microscopy, only provide two-dimensional anecdotes of the microstructure, and thus limited information about how regions are interconnected in three-dimensional space. Here we demonstrate the use of dual-beam focused ion beam-scanning electron microscopy to make a complete three-dimensional reconstruction of a solid-oxide fuel-cell electrode. We use this data to calculate critical microstructural features such as volume fractions and surface areas of specific phases, three-phase boundary length, and the connectivity and tortuosity of specific subphases.

Abstract: A carbon nanofiber-based electrode, exhibiting a large accessible surface area (derived from the nanometer-sized fiber diameter), high carbon purity (without binder), relatively high electrical conductivity, structural integrity, thin web macromorphology, a large reversible capacity (ca. 450 mA h g–1), and a relatively linearly inclined voltage profile, is fabricated by nanofiber formation via electrospinning of a polymer solution and its subsequent thermal treatment. It is envisaged that these characteristics of this novel carbon material will make it an ideal candidate for the anode material of high-power lithium-ion batteries (where a high current is critically needed), owing to the highly reduced lithium-ion diffusion path within the active material.

Abstract: Recently, a new hybrid supercapacitor, integrating both the advantages of supercapacitors and lithium-ion batteries, was proposed and rapidly turned into state-of-the-art energy-storage devices with a high energy density, fast power capability, and a long cycle life. In this paper, a new hybrid supercapacitor is fabricated by making use of the benefits of 1D nanomaterials consisting of a carbon nanotube (CNT) cathode and a TiO2–B nanowire (TNW) anode, and the preliminary results for such an energy-storage device operating over a wide voltage range (0–2.8 V) are presented. The CNT–TNW supercapacitor is compared to a CNT–CNT supercapacitor, and discussed with regards to available energy densities, power capabilities, voltage profiles, and cycle life. On the basis of the total weight of both active materials, the CNT–TNW supercapacitor delivers an energy density of 12.5 W h kg–1 at a rate of 10 C, double the value of the CNT–CNT supercapacitor, while maintaining desirable cycling stability. The combination of a CNT cathode and a TNW anode in a non-aqueous electrolyte is proven to be suitable for high-performance hybrid supercapacitor applications; this can reasonably be assigned to the interesting synergistic effects of the two nanomaterials. It is hoped that the results presented in this study might renew interest in the design of nanomaterials that are applicable not only to hybrid supercapacitors, but also to energy conversion and storage applications of the future.

Abstract: The performance of oxygen reduction catalysts (platinum, pyrolyzed iron(ll) phthalocyanine (pyr-FePc) and cobalt tetramethoxyphenylporphyrin (pyr-CoTMPP)) is discussed in light of their application in microbial fuel cells. It is demonstrated that the physical and chemical environment in microbial fuel cells severely affects the thermodynamics and the kinetics of the electrocatalytic oxygen reduction. The neutral pH in combination with low buffer capacities and low ionic concentrations strongly affect the cathode performance and limit the fuel cell power output. Thus, the limiting current density in galvanodyanamic polarization experiments decreases from 1.5 mA cm(-2) to 0.6 mA cm(-2) (pH 3.3, E(cathode) = 0 V) when the buffer concentration is decreased from 500 to 50 mM. The cathode limitations are superposed by the increasing internal resistance of the MFC that substantially contributes to the decrease of power output. For example, the maximum power output of a model MFC decreased by 35%, from 2.3 to 1.5 mW, whereas the difference between the electrode potentials (deltaE = E(anode) - E(cathode)) decreased only by 10%. The increase of the catalyst load of pyr-FePc from 0.25 to 2 mg cm(-2) increased the cathodic current density from 0.4 to 0.97 mA cm(-2) (pH 7, 50 mM phosphate buffer). The increase of the load of such inexpensive catalyst thus represents a suitable means to improve the cathode performance in microbial fuel cells. Due to the low concentration of protons in MFCs in comparison to relatively high alkali cation levels (ratio C(Na+,K+)/C(H+) = 5 x E5 in pH 7, 50 mM phosphate buffer) the transfer of alkali ions through the proton exchange membrane plays a major role in the charge-balancing ion flux from the anodic into the cathodic compartment. This leads to the formation of pH gradients between the anode and the cathode compartment.

Abstract: Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (APEM=3.5, 6.2, or 30.6 cm2). For a fixed anode and cathode surface area (AAn=ACat=22.5 cm2), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m2 (APEM=3.5 cm2), 68 mW/m2 (APEM=6.2 cm2), and 190 mW/m2 (APEM=30.6 cm2). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2ACat=APEM=2AAn, the maximum power densities of the three different MFCs, based on the surface area of the PEM (APEM=3.5, 6.2, or 30.6 cm2), were the same (168±4.53 mW/m2). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

Abstract: An upflow microbial fuel cell (UMFC) system with a U-shaped cathode inside the anode chamber was developed and produced a maximum volumetric power of 29.2 W/m3 at a volumetric loading rate of 3.40 kg COD/(m3 day) and an operating temperature of 35 °C while feeding sucrose continuously. The Coulombic efficiency decreased from 51.0% to 10.6% with the increase in the volumetric loading rate from 0.57 to 4.29 kg COD/(m3 day). In addition, the lab-scale UMFC maintained soluble chemical oxygen demand (COD) removal efficiencies exceeding 90% and volatile fatty acid concentrations of ∼40 mg/L, indicating efficient wastewater treatment. The analysis of impedance spectroscopy, generated by fitting experimental data into an equivalent circuit, revealed that at a volumetric loading rate of 3.40 kg COD/(m3 day) the overall internal resistance was 17.13 Ω. This internal resistance was composed of electrolyte resistance (8.62 Ω), charge-transfer resistance (7.05 Ω), and diffusion resistance (1.46 Ω). Electrolyte resista...

Abstract: An organic electroluminescent element including at least an emission layer sandwiched between an anode and a cathode, wherein the emission layer comprises at least a compound represented by Formula (A),

Abstract: Development of solid oxide fuel cells (SOFC) for operation at intermediate temperatures of 600–800 °C with hydrocarbon fuels requires a cathode and anode with high electrocatalytic activity for O2 reduction and direct oxidation of hydrocarbon fuels, respectively. Wet impregnation is a well known method in the development of heterogeneous catalysts. Surprisingly, very few have concentrated on the application of the wet impregnation technique to deposit nano-sized particles into the established electrode structure of the SOFC. This paper reviews and discusses the progress in the application of the wet impregnation technique in the development of Ni-free Cu-based composite anodes, doped CeO2-impregnated (La, Sr)MnO3 (LSM) cathodes and Ni anodes, Co3O4-infiltrated cathodes and precious metal-impregnated electrodes. Enhancement in the electrode microstructure and cell performance is substantial, showing the great potential of the wet impregnation method in the development of high performance and nano-structured electrodes with specific functions. However, the long-term stability of the impregnated electrode structure needs to be addressed.

Abstract: The perovskite (La0.75Sr0.25)Cr0.5Mn0.5O3 (LSCM) is shown to be an effective, redox-stable electrode that can be used for both cathode and anode SOFC operation, to provide a symmetrical fuel cell system with good performance characteristics.

Abstract: Point defects largely govern the electrochemical properties of oxides: at low defect concentrations, conductivity increases with concentration; however, at higher concentrations, defect-defect interactions start to dominate. Thus, in searching for electrochemically active materials for fuel cell anodes, high defect concentration is generally avoided. Here we describe an oxide anode formed from lanthanum-substituted strontium titanate (La-SrTiO3) in which we control the oxygen stoichiometry in order to break down the extended defect intergrowth regions and create phases with considerable disordered oxygen defects. We substitute Ti in these phases with Ga and Mn to induce redox activity and allow more flexible coordination. The material demonstrates impressive fuel cell performance using wet hydrogen at 950 degrees C. It is also important for fuel cell technology to achieve efficient electrode operation with different hydrocarbon fuels, although such fuels are more demanding than pure hydrogen. The best anode materials to date--Ni-YSZ (yttria-stabilized zirconia) cermets--suffer some disadvantages related to low tolerance to sulphur, carbon build-up when using hydrocarbon fuels (though device modifications and lower temperature operation can avoid this) and volume instability on redox cycling. Our anode material is very active for methane oxidation at high temperatures, with open circuit voltages in excess of 1.2 V. The materials design concept that we use here could lead to devices that enable more-efficient energy extraction from fossil fuels and carbon-neutral fuels.

Abstract: The behavior of platinum dissolution and deposition in the polymer electrolyte membrane of a membrane-electrode-assembly (MEA) for a proton-exchange membrane fuel cell (PEMFC) was studied using potential cycling experiment and high-resolution transmission electron microscopy (HRTEM). The electrochemically active surface area decreased depending on the cycle number and the upper potential limit. Platinum deposition was observed in the polymer electrolyte membrane near a cathode catalyst layer. Platinum deposition was accelerated by the presence of hydrogen transported through the membrane from an anode compartment. Platinum was transported across the membrane and deposited on the anode layer in the absence of hydrogen in the anode compartment. This deposition was also affected by the presence of oxygen in the cathode compartment.

Abstract: With pure hydrogen as the fuel, PEM fuel cell operation at or near 100% fuel utilization is desirable to achieve a high stack efficiency and zero emissions. However, typical membranes used in PEM fuel cells allow a finite amount of permeation rates or crossover of hydrogen, oxygen, and nitrogen across the membrane. The hydrogen and oxygen that permeate through the membrane are consumed with the generation of heat and water but without the generating of useful work, leading to a fuel inefficiency. Nitrogen crossover, on the other hand, from the cathode side to the anode side accumulates at the exit of the anode flow fields, lowering the hydrogen concentration and resulting in local fuel starvation. In this study, an in-situ electrochemical technique has been applied to determine the magnitude of the hydrogen crossover over a range of relevant fuel cell operating temperatures and pressures. Permeability coefficients thus obtained are compared to values reported in the literature. A mathematical model is developed to predict the extent of nitrogen accumulation along the anode flow fields, and fuel recycle as a mitigation method is simulated by improving hydrogen distribution. The model results were validated by comparison with experimental results. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Abstract: PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which can prevent the unevenness of thickness of a battery and has a high volume energy density by efficiently obtaining a battery capacity SOLUTION: A winding electrode 10 is divided by a center line 25 into two in a direction of thickness and one side and the other side are specified A cathode active substance layer applied end 21 on the side of starting a winding and an anode active substance layer applied end 22 and a cathode lead 2 and an anode lead 7 are positioned on the one side The cathode active substance layer applied end 21 on the side of starting a winding is positioned in a range between an edge of a first arc 26a of the cathode lead 2 and an edge of a second arc 26d of the anode lead 7 The cathode active substance layer applied end 23 on the side of ending the winding and the anode active substance layer applied end 24 is positioned in the first arc 26a COPYRIGHT: (C)2007,JPO&INPIT

Abstract: Surface modification of indium tin oxide (ITO)-coated substrates through the use of self-assembled monolayers (SAMs) of molecules with permanent dipole moments has been used to control the anode work function and device performance in molecular solar cells based on a CuPc:C60 (CuPc: copper phthalocyanine) heterojunction. Use of SAMs increases both the short-circuit current density (Jsc) and fill factor, increasing the power-conversion efficiency by up to an order of magnitude. This improvement is attributed primarily to an enhanced interfacial charge transfer rate at the anode, due to both a decrease in the interfacial energy step between the anode work function and the highest occupied molecular orbital (HOMO) level of the organic layer, and a better compatibility of the SAM-modified electrodes with the initial CuPc layers, which leads to a higher density of active sites for charge transfer. An additional factor may be the influence of increasing electric field at the heterojunction on the exciton-dissociation efficiency. This is supported by calculations of the electric potential distribution for the structures. Work-function modification has virtually no effect on the open-circuit voltage (Voc), in accordance with the idea that Voc is controlled primarily by the energy levels of the donor and acceptor materials.

Abstract: The degradation behavior of anode supported solid oxide fuel cells (SOFCs) was investigated as a function of operating temperature and current density. Degradation rates were defined and shown to be mainly dependent on the cell polarization. The combination of a detailed evaluation of electrochemical properties by impedance spectroscopy, in particular, and post-test microscopy revealed that cathode degradation was the dominant contribution to degradation at higher current densities and lower temperatures. The anode was found to contribute more to degradation at higher temperatures. Generally, the degradation rates obtained were lower at higher operating temperatures, even at higher current densities. A degradation rate as low as 2%/1000 h was observed at 1.7 A/cm 2 and 950°C over an operating period of 1500 h.