Room temperature gas sensors based on laser-annealed ZnO nanostructures for gaseous pollutants detection

To effectively control gaseous pollutants in air it is mandatory to fabricate reliable and non-expensive monitoring systems that can be easily deployed in urban areas. Sensing devices based on metal oxide nanostructures offer many advantages respect bulk material in detecting multiple hazardous gases such as, high stability, easy surface functionalization and potentially low operating temperature. Among diverse nanostructures, ZnO nanorods can be obtained with low cost and simple process at a low manufacturing temperature opening the possibility to integrate the material with flexible substrates. Additionally, laser annealing procedure can be exploited to improve or tune the morphology and the electrical properties of these materials. In this work, we present a comparison between the performance of as deposited and laser-annealed devices in the detection of NO and NO2. Different sensors characteristics at increasing gas concentrations and dynamic behaviors are shown and discussed evaluating the mechanisms involved in the diverse pollutant detection. As result, the laser-annealed sensor exhibits a sensitivity one-order higher respect to as-grown sample in detecting NO (3.9x10(-3) vs 2.7x10(-4) [1/ppm]) while for NO2 sensitivity is more than four times higher (3.8x10(-3) vs 8.4x10(-4) [1/ppm]).