Hi All,
I want to know how can we know that a specific metal oxide material can be used for a specific target gas. I mean WO3 is used for Acetone sensing most of the times, but how one can know that a specific material will give sensing response for a specific target gas
That's a very good question. I have also been looking for the answer. I hope someone will reply.
As you know, when the electrical conductivity of a material is linearly correlated to the concentration of the gas molecules adsorbed to the surfaces of that material, the later can be used as sensing material to that gas. Thus, your question is now turned to "How and Why the gas molecules are adsorbed in such a way to some surfaces rather than others?".
There are many theories that try to correlate the adsorption to the structure of the surface. Geometrical and/or electronic considerations are involved in these theories.
For more details, please refer to:
A. Clark, The Theory of Adsorption and Catalysis, Academic, New York (1970).
Most of the semiconductors can be used as sensing materials, such as ZnO, SnO2, WO3 and etc. They have been used either pure or doped with other materials to improve their sensing properties. So, you will not find a list of information telling you which material is suitable for specific sensing. The best way is that you perform a search to see that which material can be used as sensor, say for acetone, and try to improve its sensing activity.
As always in science there are two approaches:
A) the empirical approach: check the literature, which material has been used to sense which type of molecules. If you make out some kind of statistics you might get an answer to the question which material to use for the sensing of a specific molecule (species). Thanks, Mohammad Kooti!
B) The chemical approach which has two sections.
B1) For a good signal-to-noise ratio you need a sensitive material = large signal difference between no-surface interaction and suface interaction with a small amount of the sensed species. This sensitivity is depending on the material and can be increased through materials design (doping) etc.
B2) In addition, the "strength" of the interaction and thus the sensitivity might also depend on the kind of interaction (electrostatic, ionic, chemical bond) and if the two materials (sensor material) and sensed species are susceptible to this.
Thus, there is no general rule - as always for complex materials and complex interactions.