Optical recognition of CO and H₂ by use of gas-sensitive Au–Co₃O₄ composite films

Abstract

Gold–cobalt oxide (Au–Co₃O₄) composite films have been prepared by the sputter-deposition of gold onto a glass plate substrate followed by pyrolysis of spin-coated cobalt 2-ethylhexanoate. The films comprise small Au particles and Co₃O₄ nanocrystals, and exhibit different and independent optical responses to CO and H₂ in air. Carbon monoxide caused only a decrease in absorbance, while H₂ caused both a decrease and an increase in absorbance at different wavelengths. Among solid-state gas sensor materials, this Au–Co₃O₄ composite film is probably the first example of an inorganic material which can be used for the recognition of CO and H₂ molecules through optical absorbance changes.

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