Effects of Au Addition to Porous CuO[sub.2]-Added SnO[sub.2] Gas Sensors on Their VOC-Sensing Properties

The effects of Au addition on the acetone response of Cu[sub.2] O-added porous SnO[sub.2] (pr-Cu[sub.2] O-SnO[sub.2] ) powders, which were synthesized by ultrasonic spray pyrolysis employing polymethyl methacrylate microspheres as a template, were investigated in this study. The 3.0 wt% Au-added pr-Cu[sub.2] O-SnO[sub.2] sensor showed the largest acetone response among all sensors. In addition, the magnitude of the acetone response was much larger than those of the ethanol and toluene responses. The catalytic activities of these gases over Au-added pr-Cu[sub.2] O-SnO[sub.2] powders were also examined to clarify the key factors affecting their acetone-sensing properties. The Au addition increased the complete oxidation activity of all gases, and the complete oxidation activity of acetone was much higher than those of ethanol and toluene. These results indicate that the oxidation behavior during the gas-diffusion process in the sensitive Au-added pr-Cu[sub.2] O-SnO[sub.2] layer of the sensors is quite important in enhancing the acetone-sensing properties.