Dilute hydrogen sulfide sensing properties of CuO-SnO2 thin film prepared by low-pressure evaporation method

A low pressure evaporation method was adopted for preparing SnO2 and CuO-SnO2 thin films. Metallic tin and copper were evaporated on the alumina substrate under a low pressure (1 torr) of air atmosphere. As observed with AFM, these evaporated films had unique microstructure in which discrete clusters of SnO2 grains (30 nm) contacted to each other two-dimensionally with large mesopores penetrating between. The film added with a small amount of CuO exhibited very high sensitivity to H2S in air, being able to detect dilute H2S close to 0.02 ppm at 300 degrees C. The high sensitivity seems to result from the unique promoting effect of CuO coupled with the unique microstructure of the film. (C) 1998 Elsevier Science S.A. Ail rights reserved.