Carbon materials support

Carbon black is the traditional support material for fuel cell cafalysfs for fhe following reasons  

However, this has not stopped the investigation of alternative carbon forms as supporfs for fuel cell cafalysts. 

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Fig. 14.22 (a) TGA curves of carbon-supported materials with or without cobalt obtained in nitrogen atmosphere (b) Chronoamperometry results for Ppy-C-Co, P3MT-C-CO and Ppy-C in 0.5 M H2S04 under oxygen (Reprinted from [221] with permission from Elsevier). 

The electrocatalytic activity of composite carbon-supported materials based on heterocyclic polymers and nickel (Pani-C-Ni, Ppy-C-Ni, P3MT-C-Ni) was also studied... 

The formation of carbonates, via the oxidation of the carbon support material in the electrodes during open circuit conditions, clogs up the pores of the gas-diffusion electrodes, and the cell performance rapidly decreases. A circulating electrolyte avoids the build up of carbonates. 

A remarkable difference in the Pt spectra of oxide- and carbon-supported platinum is especially clear for the 2.5-nm sample the fuel cell material shows much less intensity at the bulk resonance position (1.138 G/kHz). A similar difference is shown by the spectrum for the 2.0-nm sample. In terms of the NMR layer model, this comparison means that the healing length is larger in the carbon-supported material. It is not clear whether this result is related to the conducting nature of the carrier or to the presence of the electrolyte comparisons between wet and dry samples are needed. 

Characteristics of carbon support materials with indicative figures on surface areeis readily obtainable... 

Carbon supports strongly affect fuel cell performance. They may influence the intrinsic catalytic activity and catalyst utilization, but also affect mass transport and ohmic losses. This makes analyses of the role of carbon materials rather complicated. Although numerous studies have been devoted to the carbon support improvement, only a few have attempted to establish relationships between the substructural characteristics of carbon support materials and cell performance. The influence of carbon supports on the intrinsic catalytic activity is the subject of Section 12.6.1. In Section 12.6.2 we consider the influence of support on macrokinetic parameters such as the catalyst utilization, mass transport, and ohmic losses. In Section 12.6.3 we review briefly recent data obtained upon utilization of novel carbon materials as supports for fuel cell electrocatalysts. 

Garcia G, Florez-Montano J, Hemandez-Creus A, Pastor E, Planes GA (2011) Methanol electrooxidation at mesoporous Pt and Pt-Ru electrodes a comparative study with carbon supported materials. J Power Sources 196 2979-2986... 

Wang, Y.-J., Wilkinson, D.P, and Zhang, J. (2011) Non-carbon support materials for polymer electrolyte membrane fuel cells. Chem. Rev., Ill, 7625-7651. 

Though these catalyst systems show reasonable activity (catalysts with activities closer to or exceeding commercial and government targets employ Pt-alloy catalysts, with their own limitations, for the ORR [7]), the durability of these materials for thousands of hours of operation is limited by the stability of both the Pt catalyst and the carbon support material. Stability concerns for Pt and carbon-based supports will be detailed in Sects. 24.1.1 and 24.1.2, respectively. 

To date, there have been two notable approaches (1) highly graphitic sp -like support materials (often with a microstructure very much different than Vulcan/ TKK) that include the synthesis of adatom (N, S, B, and P)-functionalized carbons and (2) non-carbon support materials, which are typically electrically conductive... 

A Study on the Role of Carbon Support Materials for Fuel-Cell Catalysts... 

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