In Russia, the mechanism of operation of promising energy-saving gas sensors was studied. This was reported by the press service of Moscow State University.
Metal oxides and semiconductor sensors created from them can detect gases in very low concentrations of up to parts per million. They are used in medicine for diagnostics, to analyze the environmental situation, or to monitor the quality and composition of food products. Such sensors are based on the transformation of gas molecules on the surface of the sensitive element (semiconductor). These transformations produce a signal that is interpreted by the electronics and depends on which compound comes into contact with the surface. However, existing sensors need to be heated to operate, which increases power consumption and reduces analysis quality. In this context, engineers are looking for a way to replace heating with activation using light.
Artem Chizhov and his colleagues decided to find out the working mechanism of photoactive sensors using the example of interaction with oxygen. Working with a simple molecule makes data easier to interpret. At the same time, oxygen plays an important role in the generation of a sensor signal during the detection of various reducing gases.
“We were the first to use mass spectrometry to study photoactive sensors,” the scientist explained. – This made it possible to find out how the oxygen concentration in the gas phase changes under conditions of illumination of a semiconductor sensitive material, and also what oxygen-containing particles are formed. [Многие ученые считают] this oxygen is removed from the surface of the semiconductor oxide, which determines both the processes of subsequent interaction with gases of various nature and the nature of the change in conductivity. We saw the reverse process – the absorption of oxygen from the gas phase. This is an interesting result.”
Among the materials frequently used for gas sensors in photoactivated oxygen isotope exchange, zinc oxide exhibits the highest activity in photoactivated processes, while tin dioxide exhibits the lowest activity. When comparing sensory properties in dark and light with oxygen, this trend continued: the sensory signal of zinc oxide increased by more than 40 times at most. Tin oxide showed the least improvement. From this it can be concluded that there is a correlation between the photoactive oxygen exchange ability and the magnitude of the sensory response to oxygen for the metal oxides studied.
The scientists hope that their work will allow the creation of devices for fast and convenient monitoring of air quality and the environment.
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