New method to selectively determine hydrogen sulfide concentrations using CuO layers

• Published in: Sensors and actuators. B, Chemical Vol. 222; pp. 625 - 631
• Main Authors: Kneer, Janosch, Knobelspies, Stefan, Bierer, Benedikt, Wöllenstein, Jürgen, Palzer, Stefan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-01-2016
• Subjects: Actuators; Copper(II)oxide; Gas sensing; Humidity; Hydrogen sulfide; Metal oxides; Modulation; Nitrogen dioxide; Phase transformations; Phase transition; Selectivity; Sensors; Surface science; Surface science; Gas sensing; Selectivity; Copper(II)oxide; Phase transition
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2015.08.071

•Use of a reversible transformation from CuO to CuS to selectively determine the hydrogen sulfide concentration.•Measuring time instead of electrical conductivity as novel metering principle.•Use of a phase transition to determine trace gas concentration.•Comprehensive study of CuO sensing response towards several trace gases in varying operating conditions.
Within this paper we demonstrate a new method to selectively determine the hydrogen sulfide (H2S) concentration using polycrystalline p-type semiconducting copper(II)oxide (CuO). Unlike commonly pursued approaches that use the resistivity of gas sensitive metal oxide layers to measure a trace gas concentration we show that the effects of a H2S induced percolation phase transition may be utilized to that end. Using a thermal modulation protocol the effects of the phase transition on the electrical behaviour of the layer may be reversed thus restoring the initial state of the layer. This forms the basis for a novel gas detection method using a semiconducting metal oxide layer. To highlight the capabilities in terms of selectivity the novel approach has been evaluated for several relevant oxidizing and reducing gases, including nitrogen dioxide (NO2), sulfur dioxide (SO2), ammonia (NH3) and H2S. The sensor response is determined at different operating temperatures and humidity levels. Due to the unique reaction towards H2S the new method enables a highly selective determination of the H2S concentration.