Investigation of Ag-Doping in Kinetically Sprayed SnO2 Composite Film and Its Application to Gas Sensor

We have developed a facile method to fabricate Ag-doped SnO2 composite film prepared via one-step kinetic spraying process. We used supersonic/subsonic nozzles to accelerate powders to their maximum kinetic energies when bombarding the substrates; no post-treatment was required. Under optimized conditions, sensors fabricated from SnO2-based films with and without Ag nanoparticles (NPs) were smooth and about 7 µm in thickness. To improve CO-sensing performance, Ag NPs (to less than 1 wt%) were added to SnO2 films. The sensor response to CO of the film with 1 wt% Ag was up to 20-fold better than that of the Ag-free film, even a low CO concentration of 500 ppm. We thus confirmed that addition of a small amount of Ag NPs to a SnO2 film increased electron transport and improved catalysis of oxygen ionization on the film surface. Therefore, we have developed a facile method of Ag-doping in composite gas sensor and this crack-free composite gas sensor was found to be highly sensitive to CO gas.