ES1.2 - Percolation-Based Chemical Switch for H2S Gas Detection
- Event
- 17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
Vienna, Austria - Chapter
- Emerging Systems 1 - Devices
- Author(s)
- T. Wagner, A. Paul, B. Schwind, M. Tiemann - Paderborn University, Department of Chemistry, Paderborn (Germany)
- Pages
- 290 - 291
- DOI
- 10.5162/IMCS2018/ES1.2
- ISBN
- 978-3-9816876-9-9
- Price
- free
Abstract
We present a nanocomposite material based on semiconducting copper oxide that exhibits stable chemical switching behavior when exposed to hydrogen sulfide (H2S). The switching is characterized by a fully reversible increase in conductance of up to seven orders of magnitude and can be explained by means of percolation theory. Exposure to distinct amounts (dosimetric sensing) of H2S at low operating temperature (160 °C) leads to the formation of a percolation path due to the selective phase transition of copper oxide (CuO, low conductivity) to copper sulfide (CuS, high conductivity). The initial state can be recovered by high-temperature treatment. However, in conventional layouts (films) this typically leads to degradation of the sensing layer structure caused by a volume decrease during CuO recovery, resulting in a low cycle stability. The nanocomposite material presented here is based on a porous silica matrix that allows for structural stabilization of the CuO/CuS system and a stabilization of the percolation threshold. The selective formation of CuS inherently minimizes cross-sensitivity to H2, CH4, CO, NH3, or NO. The material is therefore suitable for such applications as monitoring the degradation process in biogas plants. In addition to the high stability during more than 900 sensingrecovery cycles, theoretical simulations will be presented that allow insight into details of the chemical mechanism.