CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO(2) Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al(2)O(3)

The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO(2) and Pt/α-Al(2)O(3) catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO(2), the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H(2), while H(2) combustion was activated by repeated exposure to H(2) gas during the periodic gas test. Selective CO sensing of the micro-TGS against H(2) was attempted using a double catalyst structure with 0.3–30 wt% Pt/α-Al(2)O(3) as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al(2)O(3) catalyst, by cancelling out the combustion heat from the AuPtPd/SnO(2) catalyst. In addition, the AuPtPd/SnO(2) and 0.3 wt% Pt/α-Al(2)O(3) double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H(2).