Nanocrystalline TiO2/SnO2 composites for gas sensors

TiO₂/SnO₂ nanocomposites are studied as potential candidates for gas sensors. Commercial metal oxide nanopowders milled for 1?h in ethanol are used for preparing nanocomposites with varied composition from 100?mol% TiO₂ to 100?mol% SnO₂. Brunauer?CEmmett?CTeller (BET) adsorption isotherms served to determine specific surface area, SSA. The particle size distribution is established by means of Dynamic Light Scattering, DLS technique. Differential Thermal Analysis and Thermogravimetry, DTA/TG measurements within the temperature range of 20?C900?°C indicate better stability of nanomaterials composed of bigger particles or agglomerates. The total mass loss varies from 0.9 to 8.5% for 100?mol% SnO₂ and 100?mol% TiO₂, respectively. The only gaseous products of decomposition are water and carbon dioxide. X-ray diffraction analysis of nanocomposites indicates two separate phases of different crystallite size, i.e., smaller rutile TiO₂ (9?nm) and larger cassiterite SnO₂ (28?nm). Gas sensor dynamic responses at 400?°C to the reducing gas??ammonia (NH₃) are detected in the concentration range extending from 100?ppm to ?5000?ppm. Nanosensor of 50?mol% SnO₂/50?mol% TiO₂ is stable and sensitive to the interaction with NH₃ and gives the highest response at 400?°C.