Sensitive and selective detection of H2S and application in the presence of toluene, benzene, and xylene

We study the conductometric response to H2S in the range from 0.6 to 100 ppm using nanostructure metal oxide decorated interfaces and demonstrate the highly selective detection of H2S in the presence of the BTEX contaminants toluene, benzene, and xylene. We evaluate the response to H2S of a porous silicon (PS) interface and this interface decorated with TiO2, SnOx, NiO, and AuxO (x ≫ 1) nanostructured deposits. The response of an AuxO decorated interface dominates those of TiO2 and SnOx, which dominate NiO. All of the decorated interfaces show a considerable enhancement of response relative to PS. The observed responses are consistent with the recently developing IHSAB principle and the observed enhancements well exceed those for other analytes. Sensor rejuvenation and the ability to deal with highly humid environments are evaluated. SnOx decorated PS is found to be highly selective for H2S with selectivity ratios well in excess of 104:1 for toluene and benzene, and well in excess of 103:1 for xylene, all of which act as weak bases. The dominance of the response for H2S relative to the BTEX aromatics toluene, benzene, and xylene has important implications for the monitoring of significant contaminants associated with the venting and flaring of natural gas pits as they are present in oil and gas formations.