Fuel cells apphcations

Hydrogen use as a fuel in fuel cell appHcations is expected to increase. Fuel cells (qv) are devices which convert the chemical energy of a fuel and oxidant directiy into d-c electrical energy on a continuous basis, potentially approaching 100% efficiency. Large-scale (11 MW) phosphoric acid fuel cells have been commercially available since 1985 (276). Molten carbonate fuel cells (MCFCs) ate expected to be commercially available in the mid-1990s (277). 

For a large number of applications involving ceramic materials, electrical conduction behavior is dorninant. In certain oxides, borides (see Boron compounds), nitrides (qv), and carbides (qv), metallic or fast ionic conduction may occur, making these materials useful in thick-film pastes, in fuel cell apphcations (see Fuel cells), or as electrodes for use over a wide temperature range. Superconductivity is also found in special ceramic oxides, and these materials are undergoing intensive research. Other classes of ceramic materials may behave as semiconductors (qv). These materials are used in many specialized apphcations including resistance heating elements and in devices such as rectifiers, photocells, varistors, and thermistors. 

Schematic indication of bipolar plates in simplified PEM fuel cells. The bipolar plates and end plates (ElectroPhen ) were designed by Bac 2 Conductive Composites Inc. (http //www.bac2. co.nk/fuel-cell-appHcations/ (accessed Dec. 2008).)...

Figure 6.22. Nyquist plots for (A) a composite electrode at -450 mV vs. SCE and (B) a Prototech electrode at 450 mV vs. SCE [22], (Reproduced from Ahn S, Tatarchuk BJ, Composite electrode structures for fuel cell apphcations. Proceedings of the 25th Intersociety Energy Conversion Engineering Conference, 1990 3 287-92, with permission from the American Institute of Chemical Engineers.)...

N. Miyake, J.S. Wainright, and R.F. Savinell. Evaluation of a sol-gel derived Nafion/sihca hybrid membrane for polymer electrol3te membrane fuel cell apphcations. II. Methanol uptake and methanol permeabihty. Journal of the Electrochemical Society 148, A905-A909 2001. 

Recently it was proposed that PEMLC electrocatalysts may also be prepared by water-in-oil microemulsions. These are optically transparent, isotropic, and thermodynamically stable dispersions of two nonmiscible liquids. The method of particle preparation consists of mixing two microemulsions carrying appropriate reactants (metal salt + reducing agent), to obtain the desired particles. The reaction takes place during the collision of water droplets, and the size of the particles is controlled by the size of the droplets. Readers are referred to the early work of Boutonnet et al. [149], the review paper of Capek [150] and refs. [128,151], and 152 for fuel cell apphcations. The carbonyl route has the ability to control the stoichiometry between bimetallic nanoparticles, but also the particle size. The reader is referred to review papers for more details [106,107]. Other methods, including sonochemical and radiation-chemical, have been used successfully for the preparation of fuel cell catalysts (see, e.g., review articles 100 and 153). 

In numerous publications, authors claim higher activity of CNF- and CNT-supported catalysts for fuel cell apphcations, which they attribute to (1) higher electron conductivity, (2) higher particle dispersion, (3) facilitated mass transport, and (4) improved water management. Unfortunately, the conclusions on the origin of the catalytic activity enhancement often lack experimental... 

F. Trotta. Preparation and characterization of sulfonated PEEK-WC membranes for fuel cell apphcations A comparison between polymeric and composite membranes. 7. Power Sources, 160(1) 139-147, 2006. 

K. Zhi, Q. Liu, R. Zhao, R. He, L. Zhang, Preparation and characterization of Cu-Ce-La mixed oxide as water-gas shift catalyst for fuel cells apphcation, J. Rare Earths 26 (2008) 538-543. 

Sulfonated aromatic polymers have been widely studied as alternatives to Nafion due to potentially attractive mechanical properties, thermal and chemical stability, and commercial availability of the base aromatic polymers. Aromatic polymers studied in fuel cell apphcations include sulfonated poly(p-phenylene)s, sulfonated polysulfones, sulfonated poly(ether ether ke-tone)s (SPEEKs), sulfonated polyimides (SPIs), sulfonated polyphosphazenes, and sulfonated polybenzimidazoles. Representative chemical structures of sulfonated aromatic polymers are shown in Scheme 3. Aromatic polymers are readily sulfonated using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, or sulfur trioxide. Post-sulfonation reactions suffer from a lack of control over the degree and location of functionalization, and the... 

Sulfonation is the final step for the preparation of polystyrene-based membranes for fuel cell apphcations. In this reaction a sulfonic acid group is added to the aromatic ring by electrophihc substitution. Sulfonation can be performed by several agents such as sulfiu ic acid, sulfur trioxide, sulfonyl chloride, acetyl sulfate, and chlorosulfonic add. 

As the degree of sulfonation increased, the degradation temperatures decreased from 500 down to 300 °C for S-PEEK, and from 500 down to 250 °C for S-PPBP. The results of elemental analysis of residues indicate a dramatic (nearly ten-fold) decrease in sulfur content of the polymers after heating at temperature above 400 °C. These data confirm that thermal stabilities of polymers are sufficient for fuel cell appHcation even at high sulfonation levels [7,35]. 

Liu B, Hu W, Robertson GP, Kim YS, Jiang Z, Guiver MD, et al. Sulphonated bipheny-lated poly(aryl ether ketone)s for fuel cell apphcations. Fuel Cells 2009 45-53. 

Nagarale, R.K., Shina, W. and Singh, P.K. 2010. Progress in ionic organic-inorganic composite membranes for fuel cell apphcations. F 388-408. 

Chen, C.-Y, Gamica-Rodriguez, J.L, Duke, C.M., Costa, F.D.R., Dicks, L.A. and Diniz-da-Costa, C.J. 2007. Nafion/polyandine/sihca composite membranes for direct methanol fuel cell apphcation. dPQ j r Sour. 166 324—330. 

Zeches, R. (2002). Carbon Nanofibers as a Hydrogen Storage Medium for Fuel Cell Apphcations in the Transportation Sector. 

As mentioned earlier, CB is prone to oxidation, the so-called carbon corrosion, which results in the loss of surface area, changes in the pore structure and finally also leads to sintering of the supported nanoparticles and eventually their loss from the support surface. This affects both the kinetics of the reaction and the electrode s mass transport behavior resulting in a significant loss of performance with operation time. Consequently, carbon support durability is considered to be a major barrier for the successful commercialization of fuel cell technology in the automotive sector. So much so, during the last decade, more than 60 publications dealt with carbon corrosion mechanisms in fuel cell apphcation [82]. 

YS. Kim, B. Einsla, M. Sankir, W. Harrison, B.S. Pivovar, Structure-property-performance relationships of sulfonated poly(arylene ether sulfone)s as a polymer electrolyte for fuel cell apphcations. Polymer 47 (11) (2(X)6) 4026 035. 

Lindstrom, B., Pettersson, L. J. (2001). Hydrogen generation by steam reforming of methanol over copper-hased catalysts for fuel cell apphcations. International Journal of Hydrogen Energy, 26, 923—933. 

Ma, X., Sprague, M., Sun, L., Song, C. (2002). Deep desulfurization of liquid hydrocarbons by selective adsorption for fuel cell apphcations. American Chemical Society, Divison of Petroleum Chemistry Preprints, 47, 48. 

This selected brief review will be focused on the research and development progress on ORR kinetics. The origin of the problem related with the low ORR activity of platinum will be discussed, followed by a review of recent progress in making more active, more durable platinum-based ORR catalysts. These include platinum alloy catalysts, platinum monolayer catalysts, platinum nanowire and nanotube catalysts, and the more recent shape- and facet-controlled platinum-alloy nanocrystal catalysts. The progress in the mechanistic understanding on the correlation between the activity and the electronic and structural properties of surface platinum atoms will be reviewed as well. The future direction of the research on platinum-based catalysts for PEM fuel cell apphcation will be proposed. 

Linnekoski JA, Juha A, Krause, AO, Keskinen J, Lamminen J, Anttila T. Processing of Raney-nickel catalysts for alkaline fuel cell apphcations. J Fuel Cell Sci Technol 2007 4(l) 45-8. 

Gennett T, Landi BJ, Elich JM, Jones KM, Alleman JL, Lamarre P, et al. Fuel cell apphcations of nanotube-metal supported catalysts. Solid State Ionics 2002... 

Tian Z, Jiang S, Liang Y, Shen P. Synthesis and characterization of platinum catalysts on multiwalled carhon nanotuhes hy intermittent microwave irradiation for fuel cell apphcations. J Phys Chem B 2006 10 5343-50. 

Yoshitake T, Shimakawa Y, Kuroshima S, Kimura H, Ichihashi T, Kudo Y, et al. Preparation of fine platinum catal5fst supported on single-wall carbon nanohoms for fuel cell apphcation. Physica B 2002 323 124-6. 

Among these catalysts, Fe- and Co-macrocyclic complexes have exhibited the highest electrocatalytic activity. These catalysts also have shown remarkable selectivity they have no catalytic activity towards methanol oxidation. Since then, Fe- and Co-macrocyclic complexes have been extensively studied as the most promising ORR selective materials in the elFort to replace expensive noble metal Pt catalysts for PEM fuel cell apphcations, including DMFC applications. 

Li Q, Hjuler HA, Bjerrum NJ. Phosphoric acid doped polybenzimidazole membranes Physicochemical characterization and fuel cell apphcations. J Appl Electrochem... 

Of primary interest for fuel-cell apphcations are the LaMnOa (LMO) surface properties, e.g. the optimal positions for oxygen adsorption, its surface transport properties, as well as the charge-transfer behavior. In fuel-cell appbcations, the operational temperature is so high (T > 800 K) that the LMO unit cell is cnbic and thus Jahn-Teller (JT) lattice deformation around Mn ions and related magnetic and orbital orderings no longer take plcice. 

Much of the current research with conductive diamonds in PEMFC research is to develop platinum deposition techniques that can result in more uniform and smaller particle sizes on the conductive surfaces of diamond. However, conductive diamonds for catalyst support applications have often been used to examine the intrinsic properties of catalytic metals because of their inertness to electrochemical processes, lack of surface corrosion, and oxide formation. They remain strong candidates for fuel cell apphcations where catalyst integrity and durability are high priorities, and where typically carbon supports may fail due to the harsh operating conditions and high operating voltages. 

Whitelocke, S. A. and Kalu, E. E. 2008. Catalytic activity and stabihty of tungsten oxide electrocatalyst for fuel cell apphcations. AIChE Annual Meeting Conference Proceedings, Philadelphia, PA, Nov. 16-21,2008 117/1-/8. 

Kreuer, K. D., Paddison, S. J., Spohr, E., and Schuster, M. 2004. Transport in proton conductors for fuel-cell apphcations Simulations, elementary reactions, and phenomenology. 

W. Zhang, J. Chen, A.I. Minett, G.F. Swiegers, CO. Too, G.G. Wallace, Novel ACNT arrays based MEA struc-ture-nano-Pt loaded ACNT/Nation/ ACNT for fuel cell appHcations, Chem. Commun. 46 (2010) 4824—4826. 

In order to prepare advanced molecules of poly(arylene ether sulfones) for fuel cell apphcations without sacrificing their excellent physical properties, Noshay and Robeson developed a mild sulfonation procedure for the commercially available bisphenol-A-based poly(ether sulfone) [62,63]. The sulfonation agents that have been used for this polymer modification are chlorosulfonic acid and a sulfur trioxide-triethyl phosphate complex. Recently, Kerres and co-workers [102] reported an alternative sulfonation process of commercial polysulfone based on a series of steps, including metalation-sulfmation-oxidation reactions. 

Byungchan, B., Yong, H. H., and Dukjoon, K., 2005 Preparation and characterization of Nafion/poly (1- vinyhmidazole) composite membrane for direct methanol fuel cell apphcation , J. Electrochem. Soc. 152 (7) A1366-A1372. 

Smitha, B., Sridhar, S., Khan, A.A. (2005) Solid polymer electrolyte membranes for fuel cell apphcations - a review. J. Membr. Sci. 259, 10-26. 

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