We present the preparation and characterization of a novel copper(II)oxide (CuO) nanofiber based sensor with very high sensitivity and selectivity to hydrogen sulfide (H2S). The working principle is based on the phase transition of semiconducting p-type CuO to strongly degenerated p-type copper sulfide (CuS) with metallic conductivity. Electrospun polymer fiber networks of polyvinyl butyrate (PVB) and Cu(NO3)2 were attached on standard gas sensing substrates and calcined to CuO at 600 °C in ambient air for 24 h. Continuous exposure to H2S (0.1–5 ppm) as well as a sequence of 1 ppm H2S pulses result in a dosimeter type behavior of the nanofiber sensors. Triggered by a certain dose (gas concentration multiplied by time) a steep conductance increase of the sensitive layer over several orders of magnitude is observed. After reaching this percolation threshold only small conductance changes were observed. These fiber based sensors show a remarkably high specificity, there is no response to carbon monoxide, hydrogen, and methane at 160 °C. The fiber network can be regenerated by raising the operating temperature to 350 °C for 30 min in absence of H2S.
Conductance change under exposure to various gases. Continuous recording with one measurement per second.