| Summary: | Among the various metal oxide additives tested, the complex of CuO is outstanding in promoting the sensing propoerties of an SnO2 sensor for H2S in air. The SnO2 sensors loaded with 5 wt. % CuO is extremely sensitive to H2S at 200 C° and below, while it is almost unsensitive to many other gases. The response to H2S is rather slow but the recovery is very rapid. Tha added CuO particles interact electronically with the surface of SnO2 (p-n junctions) to make the sensor highly resistive, while the interaction is disconnected when CuO is sulfurized to CuS in the H2S containing atmosphere, leading to a drastic decrease in electrical resistance. The H2S sensing properties, particularly the rate of response of CuO/SnO2 sensors are influenced by the CuO loadings andoperating temperature as well as the thickness of Cuo loading film.
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