Nanoporous Titania Gas Sensing Films Prepared in a Premixed Stagnation Flame

We examine the conductometric CO sensing of TiO2 nanoparticle films prepared with a recently developed flame technique. Porous films of crystalline TiO2 nanoparticles Were grown directly on interdigitated electrodes by repeatedly translating electrodes over a premixed stagnation flame doped with titanium,tetraisopropoxide as the titanium precursor. Flame deposited electrodes with particle diameter around 9 nm show enhanced sensitivity to CO by up to an order of magnitude compared to sensing films prepared using a commercial TiO2 powder with the particle diameter around 25 nm. A gas surface model is used to examine chemical kinetic and equilibrium behaviors and explain the sensor responses. The analysis shows that the nature of the gas surface reactions is similar between these films. The desirable feature of flame-deposited sensing film is attributed to the smaller particle size which provides a greater surface area and a more electrically sensitive conduit.