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gas distribution layer of coarse-grained material Most of the electrodes that were manufactured from 1950 to 1970 with the sintered method were for use in fuel cells. This type of production was dropped for economic reasons because the electrodes were thick and heavy, with a common thickness of 2 mm, while the individual layers had to be very ...
Gas separation across a membrane is a pressure-driven process, where the driving force is the difference in pressure between inlet of raw material and outlet of product. The membrane used in the process is a generally non-porous layer, so there will not be a severe leakage of gas through the membrane.
The oxidizing gas (e.g., pure O 2, O 2 in air, CO 2, etc.) percolates through a hydrophobic layer on the gas diffusion electrode, acting as a cathode. After the gas diffuses to the electrically conducting layer acting as an electrocatalyst (e.g., hydrophilic activated carbon), the gas is electrochemically reduced.
This is the case when corrosive gases diffuse through the oxidative layer towards the metal surface (if we assume that concentration of gases in the environment is constant and the diffusion space – that is, the corrosion product layer – is semi-infinite, starting at 0 at the surface and spreading infinitely deep in the material). If, in ...
At slow scan rates, the diffusion layer is large, on the order of micrometers, whereas at fast scan rates the diffusion layer is nanometers in thickness. The relationship is described in part by the Cottrell equation. [2] Relevant to cyclic voltammetry, the diffusion layer has negligible volume compared the volume of the bulk solution. For this ...
However, the rib partially covers the gas diffusion layer (GDL) and the resultant gas-transport distance is longer than the inter-channel distance. Furthermore, the contact pressure between the GDL and the rib also compresses the GDL, making its thickness non-uniform across the rib and channel [55]. The large width and non-uniform thickness of ...
The layers of the cell were deposited as follows onto a gas diffusion stainless steel electrode: electrocatalyst, CsH 2 PO 4 electrolyte, second electrocatalyst, and the final gas diffusion layer. As is typical for most fuel cell systems, the entire cell sandwich must be uniaxially pressed to enhance adhesion at the interfaces between layers.
For diffusion of gases in porous media this equation is the formalization ... A semipermeable membrane is a thin layer of material that contains holes of various ...