Trimethylamine-sensing mechanism of TiO2-based sensors 2. Effects of catalytic activity of TiO2-based specimens on their trimethylamine-sensing properties

The effects of metal additives on the catalytic of TiO₂ for trimethylamine (TMA) oxidation have been investigated in relation to their TMA-sensing properties. The catalytic activity is more or less enhanced by adding a small amount of Ru, In or Au, the behaviour being in good agreement with the fact that these metals are effective in promoting the TMA sensitivity. In contrast, it is found that too great an enhancement in the catalytic activity induced by the addition of Pd, Pt or Rh results in deterioration of the sensitivity. Referring to the relationship between the catalytic activity and the TMA-sensing property, a possible mechanism is discussed.