T. Sauerwald

2.3.4 Electrospun Copper(II)oxide Fibers as Highly Sensitive and Selective Sensor for Hydrogen Sulfide Utilizing Percolation Effects

We propose a novel sensor for the detection of hydrogen sulfide (H2S) using a network of electrospun copper(II)oxide (CuO) fibers. The Sensor is very sensitive to H2S with a detection limit below 0.1 ppm and exhibits no response to reducing gases like carbon monoxide, hydrogen, methane or ammonia. This selectivity to H2S is advantageous in highly contaminated gas samples e.g. in biogas reactors. These properties are due to an unique sensor mechanism based on a reversible phase transition of p-type CuO to degenerated p-type copper sulfide (CuS) in the vicinity of the surface. At a temperature of 160°C the sensor shows a steep increase of conductance after a time span tc , which depends on the offered H2S concentration. We investigated this mechanism by using a CuO thin film as a model sensor and interpret the result in a framework of percolation theory. For regeneration the sensor has to be heated up to 350°C to convert the CuS back into CuO.