Polarization Characteristics of the Hydrogen Gas Diffusion Electrode

The anodic oxidation of hydrogen is studied on a large horizontal electrode covered with an electrolyte film of millimeter thickness. Polarization curves and the potential distribution in the film are obtained for various film thicknesses and electrolyte concentrations. Concentration gradients in the film electrolyte are measured and found to be very small. Convection in the film and water transport above the film are shown to exist. Both phenomena appear to be significant factors in keeping the concentration gradients small. Theoretical considerations suggest that the convection is induced by surface tension gradients. The convection is formally taken into account in an analysis of the rate‐controlling transport of the reacting gas through the film. This involves the introduction of a diffusion layer thickness as parameter. Excellent agreement is found between experimental and calculated polarization curves and potential distribution. The phenomena occurring at the model electrode are believed to represent similar phenomena occurring at actual gas diffusion electrodes. Certain ramifications also exist with regard to wet corrosion.

“…According to Eq. [6] and Fig. 6, the maximum diffusion current should start at lower potentials for the larger film thicknesses.…”

Section: Motion Induced By Surface Tension--the Formationmentioning

confidence: 80%

Section: Motion Induced By Surface Tension--the Formationmentioning

confidence: 99%

Phenomena at an Electrode Covered with an Electrolyte Film

Will

1967

“…As H/8o increases, the onset of the limiting current is delayed according to Eq. [14]. For 8o > 10 -5 cm, diffusion control prevails and H hardly affects the current as long as It << I~.…”

Section: Single Pore Polarizationmentioning

confidence: 95%

“…Mathematical analyses of the film model have been presented (12)(13)(14)(15)(16)(17)(18) and evaluated by describing polarization curves observed on model electrodes (1,10,12,13,18). More refined geometric and kinetic models are required to describe polarization curves of actual porous gas electrodes, and very few attempts have been made in this direction (17,19,20).…”

mentioning

confidence: 99%

Significance of Electrolyte Films for Performance of Porous Hydrogen Electrodes

Will¹,

BenDaniel²

1969

A refined analysis of the electrolyte film model is presented and evaluated on experimental polarization curves of porous hydrogen diffusion electrodes. Simultaneous diffusion and kinetic control and the existence of hydrogen surface coverage are taken into account. The effects of electrolyte film thickness and height on the shape of the polarization curves are analyzed. Polarization curves obtained on various types of partly wet‐proofed porous hydrogen electrodes are in very good agreement with the computed curves. A concept of the morphology and the wetting behavior of partly wet‐proofed electrodes is developed based on electron micrographs and a comparison between predicted and observed polarization curves. It is concluded that, under often prevailing conditions of diffusion control, the reaction proceeds predominantly on the wetted walls of macro pores, while the much smaller micro pores are mostly flooded and contribute little to the current.

“…Some recent models by Gurevich (6), Rockett (7), Iczkowski (8), and Burshtein et al (9), have incorporated the possibility of a thin film existing on the walls of the gas filled pores or cavities within the electrode. Other models have been proposed which attempt to explain the behavior of porous electrodes in terms of certain assumed microstructures of the porous matrix.…”

Section: Rain) Reported By Mazitov Et Almentioning

confidence: 99%

Current Distribution at a Gas-Electrode-Electrolyte Interface

Bennion¹,

Tobias²

1966

The dynamic behavior of a cathodic oxygen electrode is critically dependent on charge and mass transport preceding and following the charge transfer recation at the electrolyte-electrode interface. A mathematical model is presented which takes into account diffusion and migration of relevant substances and the solubility of oxygen in the electrolyte. The model accounts for the concentration dependence of transport properties. A comparison of the theoretical and experimental results indicates that the current density distribution is controlled by a balance between charge transfer overpotential and ohmic resistance drop in the electrolyte film. Because of the much greater length of diffusion paths, and consequent slowness of oxygen transport, a relatively small fraction of the charge transfer reaction occurs on the electrode area below the top of the intrinsic meniscus. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.49.23.145 Downloaded on 2015-03-14 to IP