Composite carbon-silicate electrode

Lev and co-workers developed the composite carbon-silicate electrode (CCE)... 

Instead of the system silica/silicate also other systems such as titania/titanate, zirconia/zirconate can be used as a reference system [xiv]. The response time of freshly fabricated thick-film sensors based on thin-film /3-alumina is very short (about 15 ms at 650 °C). After several weeks of operating this time increases 10 times (150 ms) [xv]. Solid electrolyte C02 sensors using Ni/carbonate composite as measuring electrode are suited for measuring of C02 in equilibrated water gases [xiv]. Using semiconducting oxides and carbonates like ITO (indium tin oxide) Nasicon-based C02 sensors are able to measure at room temperature [xvi]. 

Carbon-ceramic composite electrodes (CCEs) and the closely related metal-sihcate electrodes are comprised of carbon or metal dispersion in sol-gel derived silicates or Or-mocers. In this construction the silicate serves as a porous binder for the conductive dispersion. The conductive component is added as powders, nanoparticles, or nanotubes whose particle size ranges between sub-millimeter and a few nanometers. The initial intention was to provide improved conductivity by the interconnected conductive powder, but soon, other favorable attributes of the metal-sihcate hybrids were discovered, including improved catalytic reactivity, biological compatibility, and control of the thickness of the wetted section of the electrodes in aqueous electrolyte. Since the metal silicate and graphite silicate call for different preparation protocols they are addressed separately. 

Four different classes of composite ceramic electrodes were reported (1) ceramic carbon electrodes, (2) metal powder-ceramic composite electrodes, (3) carbon nanotube-silicate composites, and (4) coated aluminosilicate-ceramic electrodes. The first two fillers are basically three dimensional, whereas the third and fourth classes represent 1-D and 2-D anisotropic fillers. 

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