This charge transfer accounts for the resistance change
observed in the sensors. It is evident that the bimetallic Pd/Ptfunctionalized
nanowires show much improved NO2-sensing
performances. The gas response of the bimetallic functionalized
SnO2 nanowires exposed to 0.1 ppm NO2 was estimated to be
∼880, which is much higher than that (∼40) of the bare SnO2
nanowires exposed to 1 ppm NO2. The response and recovery
times of the bimetallic functionalized SnO2 were as short as 13
and 9 s, respectively, which are much shorter than those (170 and
320 s) of the bare SnO2 nanowires. The gas responses measured