Preparation and characterization of SnO2 and WOx–SnO2 nanosized powders and thick films for gas sensing

SnO2 powders pure and added with W6+ at two different loadings (1 and 5 W mol%), were prepared via a sol–gel route. Thick films prepared from the powders were used as CO and NO2 gas sensors. The morphology of the powders was analyzed by TEM, HRTEM and that of films by SEM. The goal of obtaining powders and films made by nanosized particles, even after thermal treatments at 850°C was attained. The effect of W on the response of powders and films towards CO and NO2 was studied by FT-IR and conductance measurements, respectively. W markedly lowered the response of SnO2 towards CO and markedly enhanced its ability to sense NO2. Surface species formed by CO and NO2 interaction were investigated.