The effect of morphology and surface doping on sensitization of quasi-1D metal oxide nanowire gas sensors

Quasi 1-D metal oxide single crystal chemiresistors are about to occupy their specific niche in the real world solid state sensorics. The major expected advantage of this kind of sensors with respect to available granular thin film sensors will be their smaller size and stable, reproducible and calculable performance within a wide range of operating conditions. To be able to compete in sensitivity with the best available nanocrystalline thin film sensors, one has to use very fine nanowires with the effective diameter of the order of ten nanometers. Fabrication of nanostructures reproducibly and controllably in this size domain remains a challenging task. The second challenge is a control of the selectivity of these nanosensors. In this report, a few exemplary approaches to grow and functionalize the prospective nanosensors are presented. Namely, in order to produce the nanostructures with the reduced diameter of the conducting channel, we grow nanowires with the oscillating morphologies where mesoscopic, several microns long segments are connected by the segments with much smaller diameters. In order to tune the sensitivity and selectivity of these sensors the influence of the surface sensitization with catalyst particles of Ni/NiO and Pd were examined.