The ZnO cluster-assembled nanowires as a highly sensitive and selective gas sensor for NO and NO.

Motivated by the recent realization of cluster-assembled nanomaterials as gas sensors, first-principles calculations are carried out to explore the stability and electronic properties of ZnO cluster-assembled nanowires and the adsorption behaviors of environmental gases on the ZnO-based nanowires, including CO, NO, NO, SO, NH, CH, CO, O and H. Our results indicate that the ultrathin ZnO cluster-assembled nanowires are particularly thermodynamic stable at room temperature. The CO, NO, NO, SO, and NH molecules are all chemisorbed on the ZnO-based nanowires with reasonable adsorption energies, but CH, CO, O and H molecules are only physically adsorbed on the nanowire. The electronic properties of the ZnO-based nanowire present dramatic changes after the adsorption of the NO and NO molecules, especially their electric conductivity and magnetic properties, however, the other molecules adsorption hardly change the electric conductivity of the nanowire. Meanwhile, the recovery time of the nanowire sensor at T = 300 K is estimated at 1.5 μs and 16.7 μs for NO and NO molecules, respectively. Furthermore, the sensitivities of NO and NO are much larger than that of the other molecules. Our results thus conclude that the ZnO-based nanowire is a potential candidate for gas sensors with highly sensitivity for NO and NO.