Nanocrystalline Oxides NixCo3−xO4: Sub-ppm H2S Sensing and Humidity Effect

In this work, p-type oxide semiconductors, Co3O4 and complex oxides NixCo3−xO4 (x = 0.04, 0.07, 0.1), were studied as materials for sub-ppm H2S sensing in the temperature range of 90–300 °C dry humid air. Nanocrystalline 0.1) prepared by coprecipitation cobalt nickel oxalates from nitrate solutions further annealing at 300 °C. The surface reactivity obtained toward both atmosphere (relative humidity 25 R.H. 60%) was investigated using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Sensor measurements showed a decrease sensor signal 1 ppm with an increase Ni content because chemisorbed oxygen species. On other hand, increases all samples increasing relative that depends on hydroxyl groups, which stimulate decomposition sulfites provide better regeneration higher temperature. This assumption additionally confirmed faster saturation conductivity curve response time