CUO-SNO2 ELEMENT FOR HIGHLY SENSITIVE AND SELECTIVE DETECTION OF H2S

Among the various metal oxide additives tested, CuO is outstanding in promoting the sensing properties of an SnO2 element for H2S in air. The SnO2 element loaded with 5 wt.% CuO is extremely sensitive to H2S at 200-degrees-C and below, while it is almost insensitive to many other gases, except for CH3SH. The response to H2S is rather slow but the recovery is very rapid. The evidence collected from X-ray photoelectron spectroscopy (XPS) measurements suggests that the added CuO particles interact electronically with the surface of SnO2 (p-n junctions) to make the element 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 elements are influenced by the CuO loadings as well as the CuO-loading methods.