Correlation between methylmercaptan gas-sensing properties and its surface chemistry of SnO 2-based sensor materials

Abstract

Methylmercaptan gas-sensing properties of SnO 2-based sensors have been investigated in the temperature range of 200–600°C. Further efforts have been directed to clarifying the reaction kinetics of CH 3SH by investigating its oxidation behavior over pure SnO 2 as well as desorption behavior of reaction products from the CH 3SH-preadsorbed pure SnO 2. A pure SnO 2 sensor exhibited a relatively high CH 3SH sensitivity of about 8000 at 250°C. Among the SnO 2-based sensors tested, only the SnO 2 loaded with 0.5 wt.% Pt exhibited slightly improved sensitivity. It was revealed that CH 3SH, CH 3SSCH 3, CH 3SCH 3, HCHO and SO 2 were adsorbed on the SnO 2 surface at 250°C during the sensitivity measurement. Although CH 3SH, CH 3SCH 3 and HCHO were suggested to be positively chemisorbed, it was confirmed that the large CH 3SH sensitivity at 250°C arose mainly from the consumption of oxygen adsorbates during the reaction with CH 3SH.