Limitations of Existing Technologies and Future Trends

Nowadays, a lot of expectations are placed on nanotechnology. Others are afraid that it is just another hype or buzzword. However, unlike, for example, dotcoms and telecoms, nanotechnology is to a greater extent enabling technology with a solid, 

FIGURE 5.14 Cross-sensitivities to various gases, such as CO, CjHg, NO, and NO2 (400 ppm each), at 800°C in humid conditions for the sensor attached with a 10 wt % CuO-added synthesized NiO-SE. (From Plashnitsa, V.V., Ueda, T., and Miura, N., Improvement of NOj sensing performances by an additional second component to the nano-structured NiO sensing electrode of YSZ-based mixed-potential-type sensor, Int. J. Appl. Ceram. Tech. 3 (2006) 127-133. With permission.) 

Bulk nanostructured materials are soUds with nanosized microstructure. Their basic units are usually nanoparticles. Several properties of nanoparticles are useful for applications in electrochemical sensors [67], However, their catalytic behavior is one of the most important. The high ratio of surface atoms with free valences to the total atoms has led to the catalytic activity of nanostructured SEs being used in electrochemical reactions. The catalytic properties of nanoparticles could decrease the overpotential of electrochemical reactions and even provide reversibility of redox reactions, which are irreversible at the bulk metal SE [68], Multilayers of conductive nanoparticles assembled on electrode surfaces produce a high porous surface with a controlled microenviromnent. These structures could be thought of as assemblies of nanoelectrodes with controllable areas. 

Basically, there are two fundamental approaches to fabricating nanomaterials 

Gobina, E., Gas sensors and gas metering Applieations and markets, BCC Report 

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