Methanol-tolerant cathode

Wen Z, Liu J, Li J (2008) Core/Shell Pt/C nanopaiticles embedded in mesoporous carbons a methanol-tolerant cathode catalyst in direct methanol fuel cells. Adv Mater 20 743-747... 

Franceschini EA, Bruno MM, Viva FA, Williams FJ, Jobbagy M, Corti HR (2012) Mesoporous Pt electrocatalyst for methanol tolerant cathodes of DMFC. Electrochim Acta 71 173-180... 

Figure 14. Design of an air-breathing laminar flow fuel cell (LFFC) showing the laminar flow profile of the anode side. Adapted with permission from Devin T. Whipple, Ranga S. Jayashree, Daniela Egas, Nicolas Alonso-Vante and Paul J.A. Kenis, Ruthenium cluster-like chalcogenide as a methanol tolerant cathode catalyst in air-breathing laminar flow fuel cells. Electrochi mica Acta 54 (2009) Copyright (2009), with permission from Elsevier.

Madhu, Singh RN (2011) Palladium selenides as active methanol tolerant cathode materials for dnect methanol fuel cell. Int J Hydrogen Energy 36(16) 10006-10012... 

Whipple DT, Jayashree RS, Egas D, Alonso-Vante N, Kenis PJA (2009) Ruthenium clusterlike chalcogenide as a methanol tolerant cathode catalyst in air-breathing laminar flow fuel cells. Electrochim Acta 54 4384—4388... 

Improvement on Methanol Anode Catalysts and Methanol Tolerant Cathode Catalysts... 

On the other hand, efforts are also being made to provide methanol-tolerant cathode catalysts. Electrochemically pretreated Bi Ir O is reported to be inactive toward methanol oxidation [3], In addition, electrochemically pretreated BijPtj gltj exhibits negligible methanol oxidation activity and shows activity for oxygen reduction reaction. The methanol tolerance increases as the Pt content decreases. Methanol-tolerant cathode catalysts will reduce the negative effects being caused by the diffused methanol. 

Despite advancement in the development of direct methanol fuel cells (DMFCs), some restrictions still inhibit their large-scale commercialization. This chapter has discussed one of the primary constraints, that is, identification of appropriate membrane materials. Nafion membranes that dominate the market of polymer electrolyte membranes allow methanol permeation from the anode to the cathode side of a DMFC. This results in serious negative consequences. Three approaches have been pursued in order to resolve the methanol permeation problem. These include Nafion membranes modification, development of alternative membranes and provision of high activity anode catalysts or methanol tolerant cathode catalysts. All the three options have achieved certain degree of success in solving the problan. Of particular interest are the Nafion membranes modification and development of alternative membranes in which membranes with permeability values of 10 to 70 times lower than the pure Nafion membranes have been developed. In general, based on the tremendous research efforts being made to develop DMFCs membranes with the best qualities, we are optimistic that very soon the issue of methanol permeation shall become a history. 

Other methanol-tolerant catalysts have been found in iron poiphyiine-type materials supported on high surface area carbon [69,70]. These catalysts were tested in fuel cell conditions and it was found that no deterioration of the electrode performance could be seen when utilizing methanol in the ceU. The catalysts are insensitive to methanol. These catalysts were also combined with a new cell concept whereby the anode and the cathode reside in the same compartment. Both electrodes are in contact with the same side of the membrane, thus eliminating most of the ohmic resistance in the cell. The fuel efficiency in the ceU at low current densities was much higher than for a normal bipolar plate design. A methanol-tolerant cathode is a prerequisite to make this concept feasible. 

For DMFC, two alternatives can be used as approaches for the fuel feed the methanol-water mixture can be fed into the cell/stack as a liquid or as a vapor. Gas feeding of the fuel minimizes the crossover problem, but it can give more problems with humidification of the ceU. Both systems have been investigated and no conclusive arguments have been found as to which of the two systems is better. Methanol crossover is still the main problem for both configurations, so the development of methanol-tolerant cathodes and better membranes remains the biggest issue for these systems [61]. 

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