New method to selectively determine hydrogen sulfide concentrations using CuO layers

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.