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51.
52.
《International Journal of Hydrogen Energy》2021,46(68):33934-33947
High temperature PEM fuel cells show enhanced tolerances regarding fuel impurities like CO for use in various applications. However, the impact of air impurities like NOx on the cell behavior is not completely understood yet. This study provides systematic investigation during 500 h of operation in presence of cathode air containing 10 ppm NO or NO2. Nitrogen oxides provoke a strongly and linearly decreasing voltage of 245.3 ± 18.5 μV h−1 and highly comparable damage that verifies similar HT-PEMFC degradation via both oxides. Cyclic voltammetry and electron microscopy reveal the loss of electrochemical catalyst surface by selectively poisoned surface and enforced catalyst particle growth. Impedance spectroscopy reveals besides increased electrode charge transfer resistances an affected proton conductivity. In contrast, SO2/NO2 impurity mixture in real occurring ratio causes less voltage decay due to a positive SO2 impact through H2SO4 formation causing further shown and discussed effects like nitrate formation and discharge. 相似文献
53.
Atsushi Tsujita Masashi Ohchi Takayuki Wakimoto 《Electrical Engineering in Japan》2019,208(1-2):17-26
We have been studying on estimating distribution of permittivity between measurement electrodes using capacitance and electric potential. Two arc electrodes were separated by long distance and there electrodes were surrounded by additional electrodes respectively. In past research work, we carried out numerical electric analysis for calculating the capacitance and electric potential using Finite Element Method (FEM) and compared with experimental and numerical results. The capacitance values were almost agreed with experimental and numerical results. However, the electric potential values were different between experimental and numerical results in conventional studies. In this paper, we proposed an equivalent circuit including the stray capacity and measurement method for capacitance, the electric potential in space between long distance electrodes was estimated. 相似文献
54.
《International Journal of Hydrogen Energy》2021,46(55):28078-28086
Interfacial hydrophobic/hydrophilic reaction fields significantly affect various reactions at the electrode surface. The hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR) have been investigated on single crystal Pt electrodes modified with hydrophobic/hydrophilic cations and anion-exchange copolymers in alkaline solutions. In alkali metal hydroxide solutions, Pt (110) exhibits the highest HER/HOR activity in the low-index planes of Pt. On the low-index planes of Pt, the hydrophilicity of the alkali metal cation in the supporting electrolyte activates the HER/HOR depending on its hydration energy. Hydrophilic cations at the interface facilitate the extraction of hydrogen from the hydrated water. The modification of anion-exchange copolymers with a hydrophobic skeleton on Pt (110) further enhanced the HER/HOR activity. The hydrogen bonding network formed around the hydrophobic species facilitated the mobility of water molecules and the OH− as the reactant/product of the HER/HOR. Appropriately forming hydrophilic and hydrophobic reaction fields at the interface improved the HER/HOR activity. 相似文献
55.
《International Journal of Hydrogen Energy》2022,47(31):14304-14318
Hydrogen evolution reaction (HER) on Au electrode in perchloric acid and NaOH solutions were studied using an inverted rotating disc electrode (IRDE). IRDE enables investigations of gas evolution reactions in a large potential and current window. In this configuration, the electrode is not obstructed by the product gas bubbles. Potentiodynamic polarization data were acquired at various concentrations of HClO4 and NaOH, and at a few electrode rotational speeds. At large over-potentials, diffusion-limited currents were observed in HClO4 solutions. In the case of HER on Au in acidic media, the Volmer-Heyrovsky-Tafel (VHT) mechanism best describes the polarization results. The fractional surface area covered by adsorbed hydrogen and the rate of reaction for individual steps were estimated using the model. At low H+ concentrations, HER proceeds mainly by the Volmer-Tafel (VT) pathway while at high H+ concentrations, Heyrovsky and Tafel pathways are equally important. In the alkaline media, HER rate was found to be independent of NaOH concentration and electrode rotational speed, and the reaction mechanism could not be identified unambiguously. The results illustrate the importance of analyzing data acquired at several reactant concentrations and at a wide potential range, to identify the reaction mechanism. 相似文献
56.
《International Journal of Hydrogen Energy》2022,47(35):15807-15819
In this study, the hetero-structure of MgCo2O4 nanowires (MCO-NWs) and microcubes (MCO-MCs) on the skeleton of nickel foam (NF) was realized through a simple hydrothermal method and subsequent annealing treatment, and then served as a binder-free cathode for assembly of high-performance hybrid supercapacitor (HSC). Such synthetic methodology avoided the traditional usage of conductive and binder reagents for the electrode fabrication. The electrochemical tests indicated its battery-type characteristics, and the MCO-NWs@NF exhibited a huge specific capacity (Cs) of 389.0 C g?1 as well as 86.2% capacity retention when the current density boosted from 1 to 10 A g?1. The assembled HSC with activated carbon (AC) as anode further demonstrated the advantages of this electrode material. After 5000 cycles at 6 A g?1, the MCO-NWs@NF//AC HSC showed good long-term cycling stability without any decay in capacitance, and could deliver an energy density (Ed) of 37.9 W h kg?1 at the power density (Pd) of 958.1 W kg?1, higher than the 30.4 W h kg?1 of MCs-based HSC. These impressive results regarding electrochemical performance suggest that MCO-NWs@NF may be a promising candidate to serve as a battery-type material in electrochemical energy storage applications such as HSCs, batteries, and so on. 相似文献
57.
《International Journal of Hydrogen Energy》2022,47(81):34492-34503
A search for efficient, durable, large-area, and economic catalyst material for low-cost production of hydrogen and oxygen is currently a high priority in the field of electrocatalysis (EC). In view of this, a cost-effective, earth abundant, highly stable, Pt free, and large-area (8 cm × 8 cm) bifunctional Ni–B electrocatalyst is reported via simple and economic SILAR method. A highly porous surface of Ni–B film with high surface wettability indicated better electrochemical water-splitting properties for the films and is obtained at 100 cycles. A Low over-potential value to obtain HER (49 mV) and OER (340 mV) at 10 mA/cm2 current suggested that they are comparable to the well-known Pt and RuO electrodes in alkaline medium (1M KOH), respectively. In actual water-splitting setup having Ni–B film (as cathode) and stainless steel (as anode), the hydrogen production of 612 ml/h is obtained at constant potential, which was enhanced by 18% i.e., 726 ml/h when a Ni–B film as both cathode and anode electrode was used. Both the electrodes are highly stable for over 15 days and interestingly they showed 7% increment in the EC performance. 相似文献
58.
Electroactive behavior assessment of poly(acrylic acid)‐graphene oxide composite hydrogel in the detection of cadmium 下载免费PDF全文
Areli Bejarano‐Jiménez Vladimir A. Escobar‐Barrios J. Mieke Kleijn Cesar A. Ortíz‐Ledón Luis F. Cházaro‐Ruiz 《应用聚合物科学杂志》2014,131(19)
Super absorbent polymers of acrylic acid‐graphene oxide (PAA‐GO) were synthesized with different percentage of chemical neutralization (0, 10, and 20%) of the acrylic acid monomer before its polymerization. The influence of their swelling and adsorption/desorption capacity of cadmium ions in aqueous solutions were studied and revealed that the GO enables greater mechanical stability in the materials. The PAA hydrogels, with the same degrees of neutralization, were also prepared without GO to compare with the composites. Additionally, carbon paste electrodes (CPE) modified with the composites PAA‐GO were used to asses and compare their adsorption properties with cadmium(II). The anodic stripping voltammetry (ASV) peak, in the differential pulse voltammetry mode, for cadmium oxidation was found to be influenced by the presence of GO into the polymer, and also by their percentage of neutralization. The accumulation of cadmium(II) on the surface of the modified CPEs was performed under open‐circuit conditions taking an account the preconcentration time of the metal cation. The presence of GO enhances the electrical signal of the electrodes in short times of immersion in cadmium(II) solutions. This property contributed to get linear responses of the CPEs modified with the composites, which were influenced by their degrees of neutralization. The PAA‐GO 10N electrode with 10% of neutralization combined the influence of GO and the degree of neutralization in the same matrix, and also showed good performance in terms of its mechanical stability, it was chosen for preliminary studies on the selectivity of the electrode toward Zn(II) and Cu(II). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40846. 相似文献
59.
The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices. 相似文献
60.