Tin dioxide nanowires were formed by using thermal evaporation and functionalized by Pd nanodots
for investigating the effect of nano-additives on NO2 sensing properties. SnO2 nanowires are uniformly
functionalized with Pd nanodots by plain micro-drop process of PdCl2. The NO2 sensing characteristics
of the Pd-functionalized SnO2 nanowires are compared with those of bare SnO2 nanowires. The
results indicate that the concentration of catalytic Pd nanodots plays an important role in the enhancement
of NO2 sensing properties. The low concentration of Pd nanodots greatly enhances the sensor
response and response time in SnO2 nanowire-based gas sensors. However, extensive addition of Pd into
the sensing layer resulted in the degradation of sensing characteristics. Moreover, the SnO2 nanowires
functionalized with excessively high concentration of Pd nanodots shows an anomalous behavior in its
output.