Thin films of supported gold catalysts for CO detection

Thin films of gold catalysts supported on Co 3 O 4 are prepared by magnetron r.f. sputtering deposition in an attempt to develop an optical fibre catalytic gas sensor. Only co-sputtering of Au and Co 3 O 4 can produce catalytic films having CO oxidation activities higher than that of an Au-free Co 3 O 4 film. The Au/Co 3 O 4 films are much more active than Pt film catalysts. A proto-type model device of the gas sensor, fabricated from the active Au/Co 3 O 4 film in combination with a temperature-sensing device, gives an output temperature increase of about 7° to 1 vol.% of CO in air at a device temperature of 150 °C.