Emergent Electrical Properties of Ensembles of 1D Nanostructures and Their Impact on Room Temperature Electrical Sensing of Ammonium Nitrate Vapor

• DOI: 10.1021/acssensors.8b00746
• Publication Date: 2018-10-23T14:57:13Z
• Authors: Lyndon D. Bastatas; Elena Echeverria-...; Phadindra Wagle; Punya Mainali; Aaron Austin; David N. McIlroy
• Keywords: Nitrates; Temperature; Electrochemical Techniques; Silicon Dioxide; 01 natural sciences; Nanostructures; 0104 chemical sciences; Explosive Agents; Limit of Detection; Electric Impedance; Adsorption; Zinc Oxide

Ammonium nitrate is an explosive agent that has a very low vapor pressure, which makes airborne detection very challenging. Detection of ammonium nitrate vapor has been achieved by using silica nanospring mats coated with a thin semiconducting layer of zinc oxide. The sensor was operated at room temperature and under ambient conditions in air. Lock-in amplification was employed to measure the change in electrical resistance of the sensor upon exposure to the said target gas analyte. The sensor showed fast detection, only taking ∼15 s to reach its peak response, and exhibited a moderate recovery time of approximately 0.5 min/20 ppm for <40 ppm exposures. A comparison between the ZnO coated nanospring sensor and ZnO thin film sensor demonstrated that the nanospring sensor has superior sensitivity and responsiveness over the thin film sensor. A percolation-based model is proposed to explain the greater sensitivity at low analyte concentrations of the ZnO-nanospring sensor, as compared to a ZnO thin film sensor.