Improved deuterium separation factor for the iron electrode prepared in a magnetic field

The electrolytic deuterium separation factors were measured in KOH aqueous solution at 298 K for the two iron films electrodeposited in no magnetic field (film (a)) and a magnetic field of 0.5 T (film (b)). The separation factors were higher for film (b) (9.8-12.3) than those for film (a) (8.7-10.2). From the exchange current density and the real surface area, it was found that film (b) has higher electrocatalytic activity for the hydrogen evolution reaction. The SEM images showed cracks on the whole surface for film (b), which suggests that the strain energy is stored. The improved electrocatalytic activity for the HER is explained by the preferred adsorption of proton due to the strain energy in the film. The increase of the deuterium separation factor is also explained by the electrocatalysis activated by the strain energy.     

Enhanced field emission properties of films consisting of Fe-core carbon nanotubes prepared under magnetic field

Films consisting of carbon nanotubes containing iron (CNTs-Fe) were prepared on tungsten substrates for electron field emission. The films were prepared by drying the mixture of the CNTs-Fe with poly [3-octyl-thiophene] (P3OT) or toluene under a magnetic field using a permanent magnet of surface magnetic flux 340 mT. The field emission properties of the films were measured in comparison with the films prepared without the magnetic field. The films prepared under the magnetic field showed better field emission characteristics than those without the magnetic field, and the electric field to generate the required field emission current was significantly decreased by applying the magnetic field in the film preparation process. Microscopic analyses indicated that the magnetic field had the effect of forcing the CNTs-Fe to stand perpendicular to the substrate, which causes the enhanced field emission properties.     

Improvement in the capacitance of a carbon electrode prepared using water-soluble polymer binder for a capacitive deionization application

It is very important to increase the wetted surface area of a carbon electrode for high capacitive deionization performance. To increase the wettability of a carbon electrode, we fabricated carbon electrodes by using water-soluble polymer binder, polyvinyl alcohol (PVA). The electrochemical properties of the PVA-bonded carbon electrode were compared with another that was prepared using hydrophobic binder, polyvinylidene fluoride (PVdF). Electrochemical methods - cyclic voltammetry, chronoamperometry, and electrical impedance spectroscopy - were used to characterize the electrochemical properties of the electrodes. As might be expected, it was confirmed that the PVA-bonded electrode was more wettable than the PVdF-bonded one, based on contact angle measurements. From the cyclic voltammetric analysis, we found that the specific capacitance was 74.4-80.3 Fg⁻¹ for the PVdF-bonded electrode and 89.6-99.8 Fg⁻¹ for the PVA-bonded electrode, depending on the potential, indicating a 13.3-30.1% increase in specific capacitance. It was observed that the ac-signal penetrated micropores of the PVA-bonded carbon electrode more deeply than the PVdF-bonded one, resulting in a higher capacitance. This was attributed to the fact that the ac-signal was able to charge more inner surface sites because micropores in the PVA-bonded electrode could be wetted due to the PVA binder.     

Enhanced light emission of GaN-based diodes with a NiO(x)/graphene hybrid electrode

A NiO(x) buffer layer is introduced in GaN-based light-emitting diodes to form low resistance ohmic contacts between p-type GaN and graphene conductive electrodes, leading to improved performance with lower operating voltage and higher light output power.     

磁场存在下制备的聚氨酯弹性体的形态

在磁场强度分别为１．５Ｔ,１．０Ｔ及不存在磁场的情况下合成了硬段质量分数均为５０％的聚氨酯（ＰＵ）弹性体,用ＷＡＸＤ和ＳＥＭ表征了它们的形态。结果表明,磁场存在下制备的ＰＵ的结晶度明显增大;磁场强度越强,ＰＵ的结晶度越大。     

Enhanced ionic conductivity of aluminum tungstate by crystallographic orientation in a strong magnetic field

The ionic conduction of multiply charged ions, rather than singly charged ions, is beneficial for energy storage and sensor applications. The low mobility of multiply charged ions is one important obstacle to the implementation of these applications. Chemical methods, such as doping and solid solution formation, have been used to improve ionic conductivity. However, the apparent performance of ceramic electrolytes can be improved by the crystallographic alignment of anisotropic grains. In this study, crystal-oriented aluminum tungstate ceramics were processed by slip casting in a strong magnetic field. The b-axis- and c-axis-oriented aluminum tungstate ceramics can be produced by this technique. The orientation of grains along the b-axis could enhance ionic conductivity by at least 1.77 times compared to that of a randomly oriented sample and 2.13 times compared to that of the c-axis-oriented sample. The results of this study suggest that this method can improve the ionic conductivity of an anisotropic material using polycrystalline processing instead of difficult single-crystal synthesis techniques.     

Enhanced magnetic properties of La2MgxNi1-xMnO6 bulks prepared at a low temperature

La₂Mg_xNi_1-xMnO₆ (LM_xNMO) bulks with different Mg doping contents (x = 0–0.40) were originally fabricated at a low temperature (700 °C). All samples exhibited a highly dense microstructure and a small grain size. A structural transition from the P2₁/n phase to the R-3 phase was indicated by XRD analysis of LM_xNMO bulks with augmented Mg doping. XPS results showed that, on account of the Mg doping, the Mn⁴⁺/Mn³⁺ ratio was significantly increased, which was the main factor in determining the degree of B-site ordering. The magnetic performances of LM_xNMO were obviously enhanced by optimizing Mg doping content. Among all the samples, LM_0.1NMO bulk had the highest B-site ordering and a lower disorder degree, which lead to it also having the maximum M_s value (47.3 emu/g, a value which demonstrates a 25% improvement compared with non-doped LNMO). Meanwhile, the high Curie temperatures of LM_xNMO bulks were attributed to the heightened density and refined grain.     

Effect of sintering additive on crystallographic orientation in AlN prepared by slip casting in a strong magnetic field

The preparation of oriented AlN bulk ceramics with and without additives was achieved by slip casting in a high magnetic field. The a and b axes of the AlN were aligned parallel to the direction of the magnetic field. The degree of crystallographic orientation was controlled by the viscosity of the slurry and the grain growth during sintering attributed to the sintering additives. The mechanical properties of the textured AlN depended on the direction of the crystallographic orientation.     

Unravelling the origin of the capacitance in nanostructured nitrogen-doped carbon - NiO hybrid electrodes deposited with laser

The full knowledge of the charge storage mechanisms occurring in complex composite electrodes is key for the straightforward development of advanced electrochemical capacitors. In this work, hybrid electrodes composed of reduced graphene oxide, multiwall carbon nanotubes and NiO nanostructures were fabricated through reactive inverse matrix assisted pulsed laser evaporation technique. Nitrogen doping of the carbon nanostructures was carried out by introducing ammonia, urea and melamine precursors in the target. The N-doped graphene electrodes exhibited a significant capacitance enhancement as compared to non-doped ones. This fact is commonly ascribed to faradaic mechanisms. However, our structural-compositional studies point to a significant change of the structural configuration of the composites at the nanoscale upon the nitrogen functionalization as the source of the electrodes’ capacitance enhancement. The composites fabricated with urea precursor exhibited the highest capacitance, and this fact was associated with the presence of pyridinic N groups that triggered the formation of a high amount of structural defects (vacancies – boundaries) and microporosity, not observed in the samples synthesized with other precursors that mainly contained pyrrolic-graphitic N.     

Analysis of abnormal grain growth of oriented LiCoO2 prepared by slip casting in a strong magnetic field

The relationship between the development of the crystallographic orientation and the grain growth behavior were studied. The degree of orientations of the green compacts and sintered samples were evaluated by the Lotgering factor. The f(0 0 l) of all the samples were drastically increased with the increasing applied magnetic field strength. The f(0 0 l) of the samples sintered at 1223 K were improved in comparison to those of the green compacts. However, the f(0 0 l) value of the samples sintered at 1273 K were not increased at 4 T or lower. To characterize the grain growth process, these samples were analyzed using electron backscatter diffraction (EBSD). The sintered samples prepared in the magnetic field at 4 T or lower showed abnormal grain growth. The samples with an applied magnetic field of 8 T or higher had no abnormal grain growth. It was revealed that the orientation angle of the particles has an effect on the grain growth.     

Giant electric double-layer capacitance of heavily boron-doped diamond electrode

The physical and electrochemical properties of boron-doped polycrystalline diamond electrodes, prepared with various B/C ratio, i.e., 0.1%, 0.5% (BDD-A), 1% (BDD-B), and 5% (BDD-C), were investigated. Electrochemical measurements of the heavily boron-doped films (BDD-C) showed giant electric double-layer capacitance and activity which is significantly larger than BDD-A and BDD-B as well as glassy carbon electrodes. However, interestingly, actual boron concentration of BDD-C was observed to be almost the same as that of BDD-B by secondary ion mass spectroscopy (SIMS) and glow discharge optical emission spectroscopy (GDOES) analysis. It is suggested that the large capacitance is due to a few sp²-bonded carbon impurities, which was observed only in BDD-C, although the amount of the sp²-bonded nondiamond species are very small. In the present work, the reason for the interesting electrochemical properties of heavily boron-doped diamond electrodes is discussed. Furthermore, dimensional stability of the electrodes was also confirmed by conducting harsh anodic treatment.     

Contribution of the metal to the differential capacitance of the ideally polarizable electrode

We have examined the direct contribution of the metal to the differential capacitance of an ideally polarizable electrode in the absence of ionic specific adsorption. Before the recent explicit calculations using the methods of surface physicists, the real importance of the metal was not realized. The basic ingredients which enter in the different models are analysed. The discussion is focused on two simple metals (Hg and Ga), and some peculiarities relative to the noble metals are emphasized.     

活性炭负载量对电极电容去离子性能的影响

增大电极比表面积是提高电容去离子效率的方法之一。通过研究活性炭负载量对电极比表面积的影响,探讨了一种提升炭电极电容去离子性能的有效方法。实验结果表明,增加活性炭负载量可有效提升电极比表面积,电极电容最高可达0.56 F/cm2,表现出较好的电容去离子性能。持续增加活性物质虽对电极内电阻影响较小,但不能进一步提高电极吸附表面,比电容急剧下降。优化电极孔隙结构是提升活性炭电极电吸附性能的有效方法。     

Copper electrodeposition in a magnetic field

The copper electrodeposition from a sulfuric acid solution was investigated in a magnetic field (0-5 T). Linear sweep voltammetry showed that both the limiting current density and the hydrogen evolution were remarkably modified in a magnetic field. Depending on the cathode overpotential, the surface morphology was divided into two groups: faceted structure and columnar dendrite. The faceted structure appeared in the electrochemical activation region and it changed into the finer grain size in a magnetic field. Furthermore, the pole figure measurement suggested that the texture evolution pattern slightly shifted from two-dimensional to three-dimensional crystal growth in a magnetic field (≥3 T). No essential microstructural variation due to the magnetic effect was observed in spite of considerable morphological variations in the region purely controlled by the mass transfer.     

Effects of NiO nanoparticles on the magnetic properties and diffuse phase transition of BZT/NiO composites

A new composite system, Ba(Zr_0.07Ti_0.93)O₃ (BZT93) ceramic/NiO nanoparticles, was fabricated to investigate the effect of NiO nanoparticles on the properties of these composites. M-H hysteresis loops showed an improvement in the magnetic behavior for higher NiO content samples plus modified ferroelectric properties. However, the 1 vol.% samples showed the optimum ferroelectric and ferromagnetic properties. Examination of the dielectric spectra showed that the NiO additive promoted a diffuse phase transition, and the two phase transition temperatures, as observed for BZT93, merged into a single phase transition temperature for the composite samples.     

Electrochemical study of NiO nanoparticles electrode for application in rechargeable lithium-ion batteries

Nickel oxide nanoparticles were synthesized via a simple and inexpensive microwave-assisted synthesis method within a fast reaction time of less than 20 min. The calcination of as-prepared precursor at 600 °C produces single phase nickel oxide. The lattice structure and morphology of the sample were investigated by X-ray diffraction, field-emission scanning electron microscopy and field-emission transmission electron microscopy. The particle size range of the nickel oxide nanoparticles varied from 50 to 60 nm. Nickel oxide nanoparticles exhibited good electrochemical performances as an anode material for lithium-ion batteries. The prepared nickel oxide anode revealed a large initial discharge capacity of 1111.08 mAh g⁻¹ at 0.03 C rate and retained 80% of initial capacity (884.30 mAh g⁻¹) after 20 cycles. Furthermore, at elevated rate of 3.7 C, the charge capacity of the nickel oxide electrode was as high as 253.1 mAh g⁻¹, which was 35% greater than that of commercial bulk nickel oxide (188 mAh g⁻¹). The enhancement of the electrochemical performance was attributed to the high specific surface area, good electric contact among the particles and easier lithium ion diffusion.     

Electrochromic properties of porous NiO thin film as a counter electrode for NiO/WO3 complementary electrochromic window

Highly porous nickel oxide (NiO) thin films were prepared on ITO glass by chemical bath deposition (CBD) method. SEM results show that the as-deposited NiO film is constructed by many interconnected nanoflakes with a thickness of about 20 nm. The electrochromic properties of the NiO film were investigated in a nonaqueous LiClO₄–PC electrolyte by means of optical transmittance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The NiO film exhibits a noticeable electrochromic performance with a variation of transmittance up to 38.6% at 550 nm. The CV and EIS measurements reveal that the NiO film has high electrochemical reaction activity and reversibility due to its highly porous structure. The electrochromic (EC) window based on complementary WO₃/NiO structure shows an optical modulation of 83.7% at 550 nm, much higher than that of single WO₃ film (65.5% at 550 nm). The response time of the EC widow is found to be about 1.76 s for coloration and 1.54 s for bleaching, respectively. These advantages such as large optical modulation, fast switch speed and excellent cycle durability make it attractive for a practical application.     

Electrochemical capacitance characterization of NiO with ordered mesoporous structure synthesized by template SBA-15

In this paper, NiO with ordered mesoporous structure was synthesized by replicating template SBA-15 and its electrochemical capacitance characterization was for the first time studied in 2 M KOH electrolyte solution. Electrochemical tests results indicated the ordered mesoporous structure can greatly increase the utilization of NiO, which is attribute to a large effective surface area due to the mesoporous structure. The capacitance of NiO with order mesoporous structure was about 120 F/g, about four times larger than that of NiO prepared by direct calcining Ni(NO₃)·6H₂O at 550 °C. On the other hand, the mesoporous NiO showed a good rate capability, which is due to that the ordered mesopores did not limit the ion motion within the pores.     

Enhanced deposition of high aspect ratio aerosols in small airway bifurcations using magnetic field alignment

The present work describes a new approach for non-invasively targeting respiratory tract deposition of high aspect ratio aerosols loaded with magnetic nanoparticles by controlling particle orientations through magnetic field alignment. Enhanced deposition of aligned particles is measured in vitro in a physical model of the small, bifurcating airways found in the lung. Unlike previous approaches to magnetic drug targeting, the approach presented herein requires no gradient in the magnetic field strength, and can be accomplished with small amounts of magnetic material compared to active drug. This approach shows promise for targeting aerosol drug delivery to specific locations within the lung.