Organic-inorganic materials fuel cell application

Organic-inorganic (sPI-SiOa) interpenetrating networks appear to be very promising materials as sohd electrolytes for fuel cell applications. Lee et al. [144] showed that the presence of sihca reduces the membrane water uptake and methanol permeability, while it increases the membrane selectivity (Fig. 3.10). In addition, the formation of an organic IPN improves the hydrolytic stability of the material. Hence, the mechanical properties (tensile strength and elongation at break) are increased by a factor of 100. 

Sol-gel techniques have been widely used to prepare ceramic or glass materials with controlled microstructures. Applications of the sol-gel method in fabrication of high-temperature fuel cells are steadily reported. Modification of electrodes, electrolytes or electrolyte/electrode interface of the fuel cell has been also performed to produce components with improved microstructures. Recently, the sol-gel method has expanded into inorganic-organic hybrid membranes for low-temperature fuel cells. This paper presents an overview concerning current applications of sol-gel techniques in fabrication of fuel cell components. 

The combination of organic and inorganic materials to develop membranes for fuel cells has become a versatile approach. Early reports and patent applications of Stonehart and Watanabe [220] and Antonucci and coworkers [221, 222] claim the advantage of the introduction of small amounts of silica particles to Na-fion to increase the retention of water and improve the membrane performance above 100 °C. The effect is believed to be a result of the water adsorption on the oxide surface. As a consequence, the back-diffusion of the cathode-produced water is enhanced and the water electro-osmotic drag from anode to cathode is reduced [205]. 

The major application of porous, three-dimensional electrodes has been in metal removal from dilute process liquors (Chapter 7) although inorganic and organic electrosynthesis applications continue to be explored (see, for example, the Dow-Huron cell for H2O2 production in Chapter 5). Many battery and fuel cell electrodes utilize an active material which is (or is supported by) a porous, three-dimensional matrix (Chapter 11), while miniature porous electrodes have found use in electrochemical detector systems for high-pressure liquid chromatography analysis (Chapter 12). 

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