Metal oxides materials show properties covering almost all aspects of material science and physics in areas including electronics, superconductivity, ferroelectricity, magnetism. Among those, metal oxides are already established in the field of gas sensing. The most common sensing mechanism consists in an electrical resistance variation upon gas chemisorption. The advantages of using single crystal nanowire of metal oxides compare to films are: a very large surface-to-volume ratio, the downsizing of sensing materials that improves the sensor performances, their stability (high degree of crystalline order), the higher capability to accommodate strain in presence of lattice mismatch, while the main challenges remains the integration in macroscopic devices with good and stable electrical contacts .
Many different binary oxides, like tin, zinc, copper, nickel, tungsten and niobium oxide were synthesized at SENSOR Laboratory directly on destination substrates by using vapor-liquid-solid technique, thermal oxidation and hydrothermal methods. These materials were fully characterized by mean of morphological and structural investigations, using FE-SEM, TEM, XRD, Raman and EDX spectroscopies, to highlight the crystalline nature of synthetized materials. Moreover, metal oxide heterojunctions were fabricated, like NiO-ZnO and graphene oxide-SnO2, in order to further increase the sensitivity and the selectivity of these compounds to target chemical species.
Functional properties of these structures as gas sensors were tested to different pollutants like CO, NO2, Ozone and many VOCs, showing the capability to use the devices in real applications like environmental monitors and electronic noses.
This work was partially supported by the European Community’s 7th Framework Programme, under the grant agreement n° 611887 “MSP: Multi Sensor Platform for Smart Building Management”.
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