Membrane electrode assemblies carbon black

The catalytic-electrocatalytic reactor consists of a membrane electrode assembly, such as Pt-black/Nafion/Pd/C sandwiched between sheets of porous carbon cloth, housed in a fuel cell assembly. 

Carbon Black (300 nin) Figure 1. Basic membrane electrode assembly. 

Figure 12.1 Schematic representation of a membrane-electrode assembly of a PEMFC. Platinnm particles and carbon agglomerates are colored in black and dark gray, respectively.

In this work, three membrane electrode assemblies (MEAs) with the same composition of the anode Pt/Ru black layer and different cathode layers were prepared. The cathode layer of the first MEA ( 1) was made using a Pt-black catalyst with 3.6 mg/cm Pt loading on the cathode side. The cathode layer of the second MEA ( 2) consisted of two layers the external Pt-black layer in contact with the gas diffusion layer (2.8 mg/cm ) and the internal Pt/C layer (0.3 mg/cm ) in contact with the membrane. The cathode layer of the third MEA ( 3) was made using carbon-supported Pt/C catalyst from Tanaka Inc. (1.3 mg/cm ). The anode layers were made in a similar way using Pt/Ru-black with 5.0 O.lmg/cm catalyst loading and 10 wt % of Nafion. 

Membrane fuel cells have zero-gap electrodes on both sides of the membrane. Typically the electrodes are made of a carbon fiber mat impregnated with platinum on carbon (Pt/C) catalyst. To achieve an extended surface for the gas to be adsorbed and react and to maintain continuity for ionic transport, interpenetration of electrode and membrane is necessary. This is usually accomplished by impregnating the porous electrode with. Nafion solution. One assembly technique is to suspend the Pt/C in Nafion solution by sonication and spray it onto carbon paper. Then the membrane is hot pressed between the two impregnated electrodes [44]. Another approach is to make an aqueous suspension of three powders - Pt/C, carbon black, and PTFE - and spray it onto the carbon paper. Then 5% Nafion solution is applied by spraying or by floating the electrode on the Nafion solution, after which the membrane is pressed between the electrodes [45]. The Nafion solution serves as an adhesive as well as a means of extending the electrolyte into the structure of the porous electrode. 

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