Sensing mechanisms of CO and H2 with NiO material – DRIFTS investigations

The response of nickel oxide gas sensors towards CO and H2 and the underlying gas sensing mechanisms were investigated with special focus on the influence of ambient humidity interference. Surface reactions were tracked by using diffuse reflectance infrared Fourier transformation spectroscopy with simultaneous resistance measurements. The sensor response to both gases is barely influenced by the background humidity. Spectroscopic results reveal that the underlying processes at the surface are almost identical for CO and H2 reception and similar to the effect of the removal of oxygen. Accordingly, the detection of the analytes is based purely on the reduction and oxidation of the oxide material instead of the formation of analyte specific surface species.