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阳极催化剂是影响直接甲醇燃料电池(DMFC)性能及成本的主要因素之一,从催化剂载体选择、复合催化剂的制备、非贵金属催化剂研究三方面综述了DMFC阳极催化剂国内外研究现状,并进行了简要分析,展望了其应用前景。 相似文献
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Carbon-supported platinum–iron catalysts were fabricated and characterised by means of scanning electron microscopy, energy-dispersive
X-ray system and X-ray diffraction. The catalysts were tested in electrochemical half cells for oxygen reduction using voltammetry
and steady-state polarisation measurements and in direct methanol fuel cells. Use of PtFe/C cathodes, instead of a Pt/C cathode,
partially suppressed methanol oxidation and led to higher net oxygen reduction currents in the presence of methanol. Consequently,
an increase in power density up to 30% was achieved in direct methanol fuel cells with PtFe/C cathodes, compared to that with
Pt/C cathode. The influence of alloy composition and operation conditions on the cell performance has been investigated. 相似文献
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The cell performance of direct methanol fuel cells (DMFC) is 0.5 V at 0.5 A cm–2 under high pressure oxygen operation (3 bar abs.) at 110 °C. However, high oxygen pressure operation at high temperatures is only useful in special market niches. Therefore, our work has now focused on air operation of a DMFC under low pressure (up to 1.5 bar abs.). At present, a power density of more than 100 mW cm–2 can be achieved at 0.5 V on air operation at 110 °C. These measurements were carried out in single cells with an electrode area of 3 cm2 and the air stoichiometry only amounted to 10. The effects of methanol concentration and temperature on the anode performance were studied by pseudo half cell measurements and the results are presented together with their impact on the cell voltage. A cell design with an electrode area of 550 cm2, which is appropriate for assembling a DMFC stack, was tested. A three-celled stack based on this design revealed nearly the same power densities as in the small experimental cells at low air excess pressure and the voltage–current curves for the three cells were almost identical. At 110 °C a power output of 165 W at a stack voltage of 1.5 V can be obtained in the air mode. 相似文献
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Jun Zhu 《Electrochimica acta》2006,51(19):4052-4060
Acidic and neutral Nafion® 115 perfluorosulphonate membranes have been modified by in situ polymerization of pyrrole using Fe(III) and H2O2 as oxidizing agents, in order to decrease methanol crossover in direct methanol fuel cells. Improved selectivities for proton over methanol transport and improved fuel cell performances were only obtained with membranes that were modified while in the acid form. Use of Fe(III) as the oxidizing agent can produce a large decrease in methanol crossover, but causes polypyrrole deposition on the surface of the membrane. This increases the resistance of the membrane, and leads to poor fuel cell performances due to poor bonding with the electrodes. Surface polypyrrole deposition can be minimized, and surface polypyrrole can be removed, by using H2O2. The use of Nafion in its tetrabutylammonium form leads to very low methanol permeabilities, and appears to offer potential for manipulating the location of polypyrrole within the Nafion structure. 相似文献
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Development of a direct methanol fuel cell (DMFC) mass flux model, using conventional transport theory, is presented and used to predict the fluid phase superficial velocity, methanol and water molar fluxes, and the chemical species (methanol and water) dimensionless concentration profiles in the polymer electrolyte membrane, Nafion® 117, of a DMFC. Implementation of these equations is illustrated to generate the numerical data as functions of the variables such as the pressure difference across the membrane, methanol concentration at the cell anode, temperature, and position in the membrane. 相似文献
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Li Liu Cong Pu Rameshkrishnan Viswanathan Qinbai Fan Renxuan Liu E.S Smotkin 《Electrochimica acta》1998,43(24):9547
A comparative study of the use of supported and unsupported catalysts for direct methanol fuel cells has been performed. The effect of catalyst loading, fuel concentration and temperature dependence on the anode, cathode and full fuel cell performance was determined in a fuel cell equipped with a reversible hydrogen reference electrode. Although the measured specific activities of supported catalysts were as much as 3-fold greater than the unsupported catalysts, membrane electrode assemblies prepared with supported catalysts showed no improvement with loadings above 0.5 mg/cm2. Fuel cells utilizing 0.46 mg/cm2 supported catalyst electrodes performed as well as unsupported catalyst electrodes with 2 mg/cm2. The temperature dependence and methanol concentration dependence studies both suggest increased methanol permeation through the thinner supported catalyst layers relative to the unsupported catalyst layers. 相似文献
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This research aims to enhance the activity of Pt catalysts, thus to lower the loading of Pt metal in fuel cell. Highly dispersed platinum supported on single-walled carbon nanotubes (SWNTs) as catalyst was prepared by ion exchange method. The homemade Pt/SWNTs underwent a repetition of ion exchange and reduction process in order to achieve an increase of the metal loading. For comparison, the similar loading of Pt catalyst supported on carbon nanotubes was prepared by borohydride reduction method. The catalysts were characterized by using energy dispersive analysis of X-ray (EDAX), transmission electron micrograph (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrum (XPS). Compared with the Pt/SWNTs catalyst prepared by borohydride method, higher Pt utilization was achieved on the SWNTs by ion exchange method. Furthermore, in comparison to the E-TEK 20 wt.% Pt/C catalyst with the support of carbon black, the results from electrochemical measurement indicated that the Pt/SWNTs prepared by ion exchange method displayed a higher catalytic activity for methanol oxidation and higher Pt utilization, while no significant increasing in the catalytic activity of the Pt/SWNTs catalyst obtained by borohydride method. 相似文献
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T. Schultz U. Krewer T. Vidaković M. Pfafferodt M. Christov K. Sundmacher 《Journal of Applied Electrochemistry》2007,37(1):111-119
The dynamic operating behaviour of the direct methanol fuel cell (DMFC) is governed by several physico-chemical phenomena
which occur simultaneously: double layer charging, electrode kinetics, mass transport inside the porous structures, reactant
distributions in the anode and cathode flowbeds etc. Therefore it is essential to analyse the interactions of these phenomena
in order to fully understand the DMFC. These phenomena were initially analysed independently by systematic experiments and
model formulations. Electrode kinetics were determined by fitting models of varying complexity to electrochemical impedance
spectroscopy (EIS) measurements. Reaction intermediates adsorbed on the catalyst seem to play a key role here. To describe
mass transport across the DMFC a one-dimensional model was formulated applying the generalised Maxwell–Stefan equations for
multi-component mass transport and a Flory–Huggins model for the activities of mobile species inside the membrane (PEM). Also
swelling of the PEM as well as heat production and transport were considered. Finally, the anode flowbed was analysed by observing
flow patterns in different flowbed designs and measuring residence time distributions (RTDs). Detailed CFD models as well
as simpler CSTR network representations were used to compare to the experimental results. Even the simpler models showed good
agreement with the experiments. After these investigations the results were combined: the electrode kinetics model was implemented
in the mass transport model as well as in the CSTR network flowbed model. In both cases, good agreement, even to dynamic experiments,
was obtained. 相似文献
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An investigation of scale-up on the response of the direct methanol fuel cell under variable load conditions 总被引:3,自引:0,他引:3
The electrical response of the direct methanol fuel cell, based on solid polymer electrolyte, to variable load is reported. The dynamic power response of the direct methanol fuel cell is of importance particularly when the cell is used for transportation applications. The study reports the dynamic characteristics of a small-scale cell (active area 9 cm2), a large-scale cell (active area 272 cm2), and a three-cell stack. The effect of operating conditions (i.e., flow rate, cathode pressure and solution concentration) on the voltage response is described and the effect of a change of scale is discussed. 相似文献
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Performance of a direct methanol fuel cell 总被引:12,自引:0,他引:12
The performance of a direct methanol fuel cell based on a Nafion® solid polymer electrolyte membrane (SPE) is reported. The fuel cell utilizes a vaporized aqueous methanol fuel at a porous Pt–Ru–carbon catalyst anode. The effect of oxygen pressure, methanol/water vapour temperature and methanol concentration on the cell voltage and power output is described. A problem with the operation of the fuel cell with Nafion® proton conducting membranes is that of methanol crossover from the anode to the cathode through the polymer membrane. This causes a mixed potential at the cathode, can result in cathode flooding and represents a loss in fuel efficiency. To evaluate cell performance mathematical models are developed to predict the cell voltage, current density response of the fuel cell. 相似文献
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A new approach to PEM fuel cell stack fabrication has been demonstrated. This approach is based on the use of light weight metal conductive elements together with nonconductive elements fabricated from engineering thermoplastics to yield a lightweight stack that can be manufactured from flat sheets of stock materials using inexpensive mass production techniques. The stack described here has a power output of over 520 W from a volume of 616 mL and a mass of 539 g for a power density of 967 W/kg and 846 W/L while operating at a pressure of 103 kPa with a 53% conversion efficiency. It is projected that with further refinement, PEM fuel cell stacks with power densities over 1,500 W/kg and 1,200 W/L can be produced. 相似文献
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This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst
loading in anodes for methanol electrooxidation. The direct methanol fuel cell’s (DMFC) anodic catalysts, Pt-Ru/C, were prepared
by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent
was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts
were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization
by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/LH2SO4 solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and
transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance
for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy
in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent
added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better
than that prepared by adding it in the solution at 0°C and then heating it up to the reducing temperature. The structure of
the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase
in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved
after heat treatment.
Translated from Journal of Harbin Institute of Technology, 2006, 38 (4): 541-545 [译自: 哈尔滨工业大学学报] 相似文献
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A model for the liquid feed, direct methanol fuel cell (DMFC), based on the homogeneous two-phase flow theory and mass conservation equation, which describes the hydraulic behaviour of internally manifolded cell stacks, is presented. The model predicts the pressure drop behaviour of the anode side of an individual DMFC cell and is used to determine the channel depth and width for fast and efficient carbon dioxide removal with minimum pressure drop. The model is used to calculate flow distribution through fuel cell stack internal manifolds. The effect of inlet and outlet manifold diameters on flow distribution is also determined. Two types of manifold design are compared, reverse flow and parallel flow. An iterative numerical scheme is used to solve the differential equations for longitudinal momentum and continuity. 相似文献