CO and NO2 gas sensitivity of nanocrystalline tin dioxide thin films doped with Pd, Ru and Rh

The effect of Pd, Ru and Rh doping on microstructure, electrical, and gas sensor properties of nanocrystalline tin dioxide films is studied. SnO2 and SnO2(M) (M=Pd, Ru, Rh) films of 0.9–1-μm thickness and a doping metal content of 0.07–1.6 at.% are synthesized by aerosol pyrolysis. Studies at 50–400 °C of the evolution of conductivity of noble metal-doped tin dioxide films put in contact with gas mixtures containing small amounts of CO and NO2 give evidence of strong similarities of the interaction mechanisms. Correlations between the electrical response and oxygen affinity of noble metal clusters were found.