Generally speaking, selectivity of a metal oxide chemiresistive gas sensor depends upon which factors? According to metal oxides gas sensing mechanism, the analyte gas will react with oxygen vacancies only.
Unless you dope the MOx, sensitivity depends on the stability of the analyte (and the decomposition products once decomposition (oxidation) has started).
By varying the temperature of the sensor, you can somewhat modulate the sensitivity: more stable analytes will not oxidize at lower sensor temperatures, while there is no way to prevent less stable analytes at higher sensor temperatures.
As the detection mechanism for combustible analytes is an oxidation process, I do not expect the decomposition process to start at oxygen vacancies - quite the contrary!
(I expect the MOx to donate oxygen for the oxidation, recovering by replenishing this oxygen from ambient air during recovery. Might be I am wrong - my experience with these sensors is an application one, not basic research.)
HI, I agree with Dreher,
The selectivity also depend on the working temperature of gas sensor. In this case, the sensor show more selectivity at a certain temperature compared with other temperatures.
Hi Harpreet,
By analogy with chemical sensors dealing with detection of electroactive species in liquid solutions, selectvity is mainly related to the detection mechanism of the sensor. As example, in the case of sensors acting as catalyst, selectivity is controlled by the chemical affinity and electrocatalytic properties of the electrode towards the analyte.
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