Fuel cells electrodes

Power can be generated when supplying suitable reactants to the electrodes (fuel-cell operation). 

Fuel cells, like batteries, convert the chemical energy residing in a fuel into electrical energy on demand. As in batteries and other electrochemical cells, fuel cells consist of an anode, where oxidation occurs, a cathode, where reduction occurs, and an electrolyte, where ions carry the current between the electrodes. Fuel cells differ from batteries in that the fuel and oxidant are not contained within the fuel... 

As for the other electrochemical storage/conversion devices, the fuel cell electrolyte must be a pure ionic conductor to prevent an internal short circuit of the cell. It may have an inert matrix that serves to physically separate the two electrodes. Fuel cells may contain all kinds of electrolytes including liquid, polymer, molten salt, or ceramic. 

Any book must leave something out, and this one has left out a good deal it does not cover membranes used in packaging materials, sensors, ion-selective electrodes, fuel cells, battery separators, electrophoresis and thermal diffusion. In this final chapter, five processes that come under the general title of other are covered briefly. 

Y. P. Sun and K. Scott, The influence of mass transfer on a porous fuel cell electrode, Fuel Cell, 4(1-2) (2004) 30-38. 

Chan SH, Chen XJ, Khor KA (2001) Reliability and accuracy of measured overpotential in a three-electrode fuel cell system. J Appl Electrochem 31 1163-70... 

An electrolyte is an essential component within fuel cells, used to facilitate the selective migration of ions between the electrodes. Fuel cells are typically classified according to the electrolytes used alkaline fuel cell (AFC), polymer electrolyte (or proton exchange membrane) fuel cell (PEMFC), phosphoric acid fuel cell (PAFC),... 

In the middle of the last century, the original form of zeolite membranes were synthesized by dispersing the zeolite crystals in polymer membrane matrixes, which were used for gas separation and pervaporative alcohol/water separations. In the last few decades, the researches of polycrystalline zeolite membranes that supported on ceramic, glass, or metal substrates have grown into an attractive and abundant field. Their applications for gas separation, pervaporation, membrane reactors, sensors, low-k films, corrosion protection coatings, zeolite modified electrodes, fuel cells, heat pumps et al. have been wildly explored. In the following text, the applications of supported polycrystalline zeolite membranes for energy and fuels will be presented. 

Key words Combustion Synthesis/Strontium Titanate/Cermet/Electrode Fuel Cell... 

Song C, Zbang L, Zbang J, Wilkinson D, Baker R. Temperature dependence of oxygen reduction catalyzed by cobalt fluoro-pbtbalocyanine adsorbed on a grapbite electrode. Fuel Cells 2007 7(1) 9—15. 

Wills RGA, Watt-Smith MJ, Walsh FC (2009) The use of fluorocarbon siufactants to improve the manufacture of PEM fuel cell electrodes. Fuel Cells 9(2) 148-156 Mansouri HR et al (2007) Fluorinated polyether additives to improve the performance of urea-formaldehyde adhesives for wood panels. J Appl Polym Sci 106(3) 1683-1688 Bultman DA, Pike MT (1981) The use of fluorochemical surfactants in Hoot polish. Chem Times Trends 4(1) 41 ... 

Song C, Zhang L, Zhang J, Wilkinson DP, Baker R (2007) Ttanpoatuie dependence of oxygen reduction catalyzed by cobalt fluoro-phthalocyanine adsorbed on a graphite electrode. Fuel Cells 7(1) 9-15... 

Optimal Nafion content in electrodes made with sulfonated sUane-treated Pt/C was around 10% wt., while the optimal Nafion content for electrodes made with untreated Pt/C was 30% wt. The performance of the former electrode with 10% Nafion was only slightly lower than that of the latter with 30% Nafion . When 10% Nafion was used with the untreated Pt/C to make the electrode, its performance was much lower than that obtained by silane-treated Pt/C (Fig. 9). Clearly, the presence of sulfonated silane contributed significantly to the proton conductivity in the electrodes. It was found that modification of the carbon support prior to the Pt deposition was more effective than modification of Pt-catalyzed carbon, presumably due to the blocking of the active Pt sites by the silane in the latter case. Also, estimates indicated that the sulfonate loading was similar at the optimal Nafion loadings for untreated and sUane-treated Pt/C electrodes. Fuel cells showed no performance loss in 12 hours of operation, indicating that the attached sulfonated silane groups were stable in the fuel cell environment. 

Keywords carbon supports, catalyst electrodes, fuel cells, nanoclusters, surface treatments, electroactivily. 

A report from Kyushu University in Japan [2], revealed that researchers there have developed a nanometre-sized, carbon fibre-based, electrode catalyst for polymer electrode fuel cells (PEFC). This catalyst uses half the platinum used in existing PEFC catalysts with consequent cost savings. Fuel cells with the new catalyst generate power at least equal to that of current PEFC. Previously it was thought that it was difficult to have nanometre-sized carbon fibre hold platinum uniformly at high density. The breakthrough achieved by the researchers was to treat the fibre surface and thereby satisfactorily prevent the platinum from coagulating. 

Figure 16-8. Scheme of a 3-electrode fuel cell with details of the hydrophobic carbon ceramic composite electrode. The inserts show unwetted (left) and flooded (middle) sections of the CCE. The active section of a wetted channels electrode is shown in the right insert (after Rabinovich and Lev, 2001). 

Bemardi, D.M., and Verbrugge, M.W (1992) A mathematical model for the solid-polymer-electrode fuel cell, J. Electrochem. Soc., 139, 2477-2491. 

The kinetics of oxidation and corrosion are of immense technological importance as well as being of profound scientific significance. While laboratory investigations have related in most cases to relatively simple studies of pure metals and a few alloys, industrial interest has been directed in very sophisticated research toward reduction in the rate of oxidation. However, it should be appreciated that on occasion, such as in the development of sacrificial anodes, electrodes for primary batteries, and in the potential development of consumable metal electrode fuel cells, an enhancement in the rate of oxidation is sought. 

A fuel cell is an electrochemical cell in which a fuel gives up electrons at one electrode and oxygen gains electrons at the other electrode. Fuel cells are increasingly used instead of petrol to power buses and cars. The fuel is stored in tanks in the vehicle and oxygen comes from the air. The energy released in a fuel cell produces a voltage which can be used to power the electric motor of the vehicle. 

Platinum Electrodes. Fuel Cells, Vol. 08, pp. 81-86 Randeniya, L.K. Bendavid, A. Martin, P.J. Preston, E. W. (2007). Photoelectrochemical and Structural Properties of Ti02 and N-Doped Ti02 Thin Films Synthesized Using Pulsed Direct Current Plasma-Activated Chemical Vapor Deposition. /. PhxfS. Chem. C, Vol. Ill, pp. 18334-18340... 

Litz, L.M., Kordescb, K.V. (1965) Technology of hydrogen xygen carhon electrode fuel cells. Advances in Chemistry Series, Al, 166-187. 

Modern EIS test systems are equipped with an equivalent circuit analysis software capability, greatly simplifying data analysis. The EIS analysis can be conducted on an individual electrode or on a full fuel cell for qualitative comparison of the various losses between different materials, electrodes, fuel cell design, or operating conditions. Note that fitting the EIS data to a given electrical circuit does not guarantee the model is correct, only that the data fit the assumed model. 

P. Tanasini, M. Cannarozzo, P. Costamagna, A. Faes, J. Van herle, A. Hessler-Wyser, C. Comninellis, Experimental and theoretical investigation of degradation mechanisms by particle coarsening in SOFC electrodes. Fuel Cells 9(5), 740-752 (2009)... 

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