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At first solid electrodes were used in the Grove cell, Francis Thomas Bacon was the first to use gas diffusion electrodes for the Bacon fuel cell, [3] converting hydrogen and oxygen at high temperature into electricity. Over the years, gas diffusion electrodes have been adapted for various other processes like: Zinc-air battery since 1980
Fuel cell systems from these manufacturers are currently being used to generate AC or DC electricity, heat, water, or any combination of the three. This list is incomplete ; you can help by adding missing items .
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 configuration allows for efficient proton conduction and effective gas diffusion, making it suitable for various applications, including fuel cell vehicles and portable power systems. Research has shown that 5-layer MEAs can provide improved performance under different operating conditions, making them a preferred choice in the industry.
PEMFCs are built out of membrane electrode assemblies (MEA) which include the electrodes, electrolyte, catalyst, and gas diffusion layers. An ink of catalyst, carbon, and electrode are sprayed or painted onto the solid electrolyte and carbon paper is hot pressed on either side to protect the inside of the cell and also act as electrodes.
The two electrodes are separated by a porous matrix saturated with an aqueous alkaline solution, such as potassium hydroxide (KOH). Aqueous alkaline solutions do not reject carbon dioxide (CO 2) so the fuel cell can become "poisoned" through the conversion of KOH to potassium carbonate (K 2 CO 3). [2]
The magnitude of the current is controlled by how much of the target gas is oxidized at the working electrode. Sensors are usually designed so that the gas supply is limited by diffusion, and thus the output from the sensor is linearly proportional to the gas concentration. This linear output is one of the advantages of electrochemical sensors ...
During the aqueous deposition process, gas is being formed at both electrodes. Hydrogen gas is being formed at the cathode, and oxygen gas at the anode. For a given amount of charge transfer, exactly twice as much hydrogen is generated compared to oxygen on a molecular basis. This has some significant effects on the coating process.