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

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.