Enhanced Response of Pd Nanoparticle–Loaded ${\rm SnO}_{2}$ Thin Film Sensor for ${\rm H}_{2}$

The sensing response of ${\rm SnO}_{2}$ thin film sensors loaded with Pd nanoparticles $({\rm Pd}\hbox {-}{\rm SnO}_{2})$ is studied for ${\rm H}_{2}$ gas. Nanoparticles of Pd catalyst of varying size (2–6 nm) are synthesized using chemical route with different concentrations of polyvinyl pyrollidone (PVP) as a stabilizing agent and dispersed over the surface of ${\rm SnO}_{2}$ thin film deposited by rf magnetron sputtering technique. The sensing response of all prepared sensors was recorded over a temperature range of 50 $^{\circ}{\rm C}$ –200 $^{\circ}{\rm C}$ . The effect of PVP used for synthesis of Pd nanoparticles has been studied on the sensing response characteristics of ${\rm Pd}\hbox {-}{\rm SnO}_{2}$ sensors. The optimized sensor structure was found to exhibit a higher response $(1.9\times 10^{3})$ at a relatively low operating temperature (150 $^{\circ}{\rm C}$ ) with fast response time $({\rm t}_{90}\sim 2~{\rm s})$ for 500 ppm ${\rm H}_{2}$ gas. The origin of enhanced sensing response is identified in the light of the interaction of PVP with Pd nanoparticles besides the spill over of ${\rm H}_{2}$ gas molecules on the uncovered surface of ${\rm SnO}_{2}$ thin film.