Effect of heterogeneous catalytic methane oxidation on kinetics of conductivity response of adsorption semiconductor sensors based on Pd/SnO2 nanomaterial

Nanosized semiconductive Pd-containing sensor materials based on SnO2 were obtained by sol-gel technique. The highly sensitive gas sensor based on 1.41wt% Pd/SnO2 nanomaterial showed the maximum response value of 12.4 to 930ppm CH4, and the kinetics of the sensor conductivity response and recovery were studied. The average particle size of the material with the highest response to methane was 14-15nm. Study of the CH4 oxidation kinetics on the surface of the 1.41wt% Pd/SnO2 sensor nanomaterial allowed the proposal of a theoretical model that can describe the kinetics of the conductivity response and recovery for such Pd-doped sensors to methane. The values of the methane oxidation activation energies obtained from the experimental kinetic data for the CH4 oxidation reaction on the 1.41wt% Pd/SnO2 gas-sensitive material and the model based on the data of the sensor conductivity response and recovery were almost the same, indicating a leading role for the heterogeneous catalytic oxidation reaction occurring on the sensor surface.