Direct methanol fuel cell approaches

Besides chemical catalytic reduction of carbon dioxide with hydrogen, which is already possible in the laboratory, we are exploring a new approach to recycling carbon dioxide into methyl alcohol or related oxygenates via aqueous eleetrocatalytic reduction using what can be called a regenerative fuel cell system. The direct methanol fuel cell... 

A. Lam, D. P. Wilkinson, and J. Zhang. Novel approach to membraneless direct methanol fuel cells using advanced 3D anodes. Electrochimica Acta 53 (2008) 6890-6898. 

Jiang, R. Rong, C. Chu, D., Combinatorial approach toward high-throughput analysis of direct methanol fuel cells, J. Comb. Chem. 2005, 7, 272-278... 

A large variety of applications using either vapor permeation or pervaporation has been reported. These include the use of pervaporation for the removal of toxic organics from water (Schnabel et al., 1998) and wastewater streams (Moulin et al., 2002), sometimes using hybrid approaches with adsorptive techniques the use of pervaporation membranes in direct methanol fuel cells (Pivovar et al., 1999) and, more recently, the resolution of isomeric mixtures (Kusumocahyo etal., 2004) and membrane-assisted enantiomer enrichment (Paris et al., 2004), in both cases using membranes containing specific complexation agents such as cyclodextrins. 

Lin Y, Li H, Liu C, Xing W, Ji X (2008) Surface-modified Nafion membranes with mesoporous Si02 layers via a facile dip-coating approach for direct methanol fuel cells. J... 

Oliveira VB, Ealcao DS, Rangel CM, Pinto AMER (2007) A comparative study of approaches fm direct methanol fuel cells modeling. Int J Hydrogen Energy 32 415-424... 

The utility of carbide and nitride catalysts has prompted numerous studies of their reactivity that use carbide and nitride overlayers as the catalyst rather than bulk carbides or nitrides. This approach permits careful manipulation of the surface metal/nonmetal stoichiometry, which is crucial to probing reactivity. These studies consistently reveal the catalytic activity of carbide and nitride overlayers and, in several cases, the similarities between their behavior and that of noble metal catalysts. For example, the same benzene yield and reaction pathway for the dehydrogenation of cyclohexane was observed for both p(4x4)-C/Mo(110) and Pt(l 11) surfaces. Furthermore, carbon-modified tungsten may be a more desirable catalyst for direct methanol fuel cells than Pt or Ru surfaces because the transition metal carbide exhibits higher activity toward methanol and water dissociation and is more CO-tolerant. ... 

Z. Miao, Y.-L. He, X.-L. Li, and J.-Q. Zou. A two-dimensional two-phase mass transport model for direct methanol fuel cells adopting a modified agglomerate approach. J. Power Sources, 185 1233-1246, 2008. 

Zhou, Y.G., Chen, XX, Wang, F.B., Sheng, Z.H. Xia, X.H. A facile approach to the synthesis of highly electroactive Pt nanoparticles on graphene as an anode catalyst for direct methanol fuel-cells. Chem. Commun. 46 (2010), pp. 5951-5953. 

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. 

The main disadvantage of Nafion is that the inverse micelles in the structure must contain water if the polymer is to conduct protons or sodium ions, and dehydration of the membrane at higher temperatures leads to failure. A second disadvantage, particularly serious in direct methanol fuel cells, is that Nafion-type membranes tend to be permeable to the methanol, giving rise to major problems. Substantial effort has recently been put into fabricating higher temperature systems, especially for use in fuel cells. The main approaches have been to form a composite between the PFSA and... 

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