Chromium‐Doped Raney Nickel Catalyst for Hydrogen Electrodes in Alkaline Fuel Cells

Kenjo, T.

doi:10.1149/1.2113845

Cited by 42 publications

(30 citation statements)

References 3 publications

(7 reference statements)

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“…Using MA it has been possible to synthesize novel materials with special physical and chemical properties. By the other hand, nickel is a relatively inexpensive and highly active non-noble metal catalyst convenient for developing hydrogen electrodes to be used in alkaline fuel cells [4]. Sturm [5] and Mund et al [6] found that its catalytic activity was enhanced by additions of transition metals such as titanium, iron and molybdenum.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical performance of hydrogen evolution reaction of Ni–Mo electrodes obtained by mechanical alloying

Rodríguez-Valdéz

Estrada-Guel

Almeraya-Calderón

et al. 2004

International Journal of Hydrogen Energy

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Section: Introductionmentioning

confidence: 99%

Electrochemical performance of hydrogen evolution reaction of Ni–Mo electrodes obtained by mechanical alloying

Rodríguez-Valdéz

Estrada-Guel

Almeraya-Calderón

et al. 2004

International Journal of Hydrogen Energy

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“…The test layer is a Raney nickel layer, the concentration polarization in which is to be measured. The load current is sustained by the working layer which is catalyzed with 0.4% chromium-doped Raney nickel (6). Use of this catalyst not only lowers the polarization loss of the working layer, but also stabilizes its polarization characteristics, thereby providing more accurate and reproducible polarization data for the test layer.…”

Section: Cell Arrangement and Polarization Measurement--thementioning

confidence: 99%

“…Chromium-doped Raney nickel catalyst.--The catalytic activity of Raney nickel is enhanced by doping a small amount of chromium (6). Figure 11 shows ~o -~ vs. thickness plots for the hydrogen electrodes catalyzed with this Raney nickel.…”

Section: Raney Nickel Hydrogen Electrodes 1587mentioning

confidence: 99%

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The Effect of Thickness on the Performance of PTFE‐Bonded Raney Nickel Hydrogen Electrodes in Relation to the Electrolyte Diffusivity of Catalyst Layers

Kenjo

1985

J. Electrochem. Soc.

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The polarization resistance of Raney nickel hydrogen electrodes decreases with increasing thickness of catalyst layers, but there is a lower limit that can be attained by the thickness effect. The present study aims to prove that this limit depends on the electrolyte diffusivity of catalyst layers. The diffusivity was measured using multilayered electrodes where a ZrO~ layer separates electronically the test layers from working layers. The theoretical polarization resistance was calculated on the basis of two different assumptions "ohmic potential drop" and "concentration polarization." The former predicts much higher electrolyte resistivity of catalyst layers than the observed value. However, the diffusivity values predicted by the latter agreed well to the experimental data. It has been thus proved that the concentration polarization assumption is valid and the electrolyte diffusivity is an essential factor to determine the lower limit of polarization resistance.The structure and operating mechanism of Raney nickel hydrogen electrodes have been described by Mund and his co-workers on the basis of a thin film model (1-3). The distinguishing feature of this model is a thin electrolyte film which covers the inside face of macropore while leaving interparticle spaces for hydrogen diffusion. The hydrogen gas dissolves into the electrolyte film at the gas/film interface after diffusing through the macropore. The film is connected with each other by the electrolyte bridge. The electrochemical hydrogen oxidation takes place at the film/catalyst interface distributed in the catalyst layer like a three-dimensional network. The catalyst layer is therefore electrochemically reactive not only at the two-dimensional electrode/electrolyte-bulk interface, but also over a zonal area extending toward the gas-side edge of the electrode. This effective reaction area is a geometrical factor to determine the polarization loss. This viewpoint predicts that the polarization loss decreases with increasing thickness of catalyst layers. The predicted relationship has been found in the Raney nickel hydrogen electrodes (3, 4).There is, however, a lower limit in the polarization loss attained by the "thickness effect." In load condition, the potential gradient arises in the thickness direction because of the ohmic resistance of the film. Taking the film resistivity pf into account and assuming a linear function between the local polarization and faradaic current density, Mund derived the polarization resistance ~0 as a function of the thickness of catalyst layers dwhere pi is the interfacial resistance between the film and catalytic surface. When the catalyst layers are very thick (pfd 2 >> pi), the polarization resistance tends to a limiting value ~/p--~. This is the explanation for the limiting thickness effect in terms of the ohmic potential drop. He estimated 10-20 ~-cm as a pf value at 80~ by parameter matching. The present author treated similarly the data of PTFE-bonded Raney nickel electrodes and obtained a value of the same order (...

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“…Although Raney nickel has excellent hydrogen adsorption ability and relatively large surface area, some disadvantages have also been reported, such as high electrolyte diffusion resistance due to low pore volume and small pore size [98,99], and insufficient conductivity [97]. One type of mitigation is to support Raney nickel on carbon blacks, which will decrease its electrolyte diffusion resistance and increase its electrical conductivity [97].…”

Section: Raney Nickelmentioning

confidence: 99%

Electrocatalytic H2 Oxidation Reaction

Li¹,

Lee²,

Zhang³

PEM Fuel Cell Electrocatalysts and Catalyst Layers

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Hydrogen (H 2 ), an important material and product in chemical industries, has been investigated as a new clean energy source for many decades [1][2][3]. With the rapid development of proton exchange membrane (PEM) fuel cell technology, in which H 2 is used as a fuel, the chemical energy stored in this H 2 can be electrochemically converted to electric energy with zero emissions and high efficiency. The dream of a hydrogen economy era therefore seems closer to reality. Beginning in the 1990s, the advantages of PEM fuel cells, including zero/low emissions, high energy efficiency, and high power density, have attracted world-wide research and development in several important application areas, including automotive engines, stationary power generation stations, and portable power devices [4]. With successful demonstrations of fuel cell technology, in particular in automotive applications, commercialization of this technology has become a strong driving force for further development in the critical areas of cost reduction and durability. The major cost of a PEM fuel cell is the platinum (Pt)-based catalysts. At our current technological stage, these Pt-based catalysts for both the cathodic O 2 reduction reaction (ORR) and the anodic H 2 oxidation reaction (HOR) are the most practical catalysts in terms of catalytic activity and lifetime stability. Therefore, research and development to improve catalytic activity and stability has shot to the fore in recent years. Although both theoretical and experimental approaches have resulted in great progress in fuel cell catalysis [2,3,5,6], continuous effort is necessary to develop breakthrough fuel cell catalysts that are cost-effective and highly durable for commercial use.With respect to fuel cell catalysis, most research has been focused on cathode ORR catalysts development, because the ORR kinetics are much slower than the anodic HOR kinetics; in other words, the fuel cell voltage drop polarized by load is due mainly to the cathode ORR overpotential [7,8]. However, in some cases the overpotential of the anodic HOR can also contribute a non-negligible portion of the overall fuel cell voltage drop [8]. Therefore, the catalytic HOR on the fuel cell anode catalyst is also worth examining.

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Chromium‐Doped Raney Nickel Catalyst for Hydrogen Electrodes in Alkaline Fuel Cells

Abstract: not Available.

Cited by 42 publications

References 3 publications

Electrochemical performance of hydrogen evolution reaction of Ni–Mo electrodes obtained by mechanical alloying

Electrochemical performance of hydrogen evolution reaction of Ni–Mo electrodes obtained by mechanical alloying

The Effect of Thickness on the Performance of PTFE‐Bonded Raney Nickel Hydrogen Electrodes in Relation to the Electrolyte Diffusivity of Catalyst Layers

Electrocatalytic H2 Oxidation Reaction

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