Optical CO detection by the plasmon absorption of Au-CuO composite films

Optical absorption of pure CuO films without Au is not sensitive to reducing gases such as CO in air at a temperature range from 175 degrees C to 300 degrees C in the visible-near IR wavelength region. The combination of small Au particles with CuO films gave rise to the optical CO sensitivity in the plasmon absorption region at this temperature range. The largest absorbance change due to CO was in the 700-800 nm wavelength region. This might be because the absorbance by small Au particles in the plasmon band was influenced by the change in the dielectric constant of copper oxide which surrounded small Au particles. The reversible absorbance change and the relatively fast response to CO over a concentration range from 50 ppm to 10000 ppm(1 vol. %) allow the Au-CuO composite films to be useful for optical CO detection.