Highly sensitive and selective hydrogen single-nanowire nanosensor

Metal oxides such as ZnO have been used as hydrogen sensors for a number of years. Through doping, the gas response of zinc oxide to hydrogen has been improved. Cadmium-doped ZnO nanowires (NWs) with high aspect ratio have been grown by electrodeposition. Single doped ZnO NWs have been isolated and contacted to form a nanodevice. Such nanosystem demonstrates an enhanced gas response and selectivity for the detection of hydrogen at room temperature compared to previously reported H2 nanosensors based on pure single-ZnO NWs or multiple NWs. A dependence of the gas response of a single Cd–ZnO nanowire on the NW diameter and Cd content was observed. It is shown that cadmium-doping in single-crystal zinc oxide NWs can be used to optimize their response to gases without the requirement of external heaters. The sensing mechanisms responsible for such improved response to hydrogen are discussed.