Temperature Dependence of Sensors Based on Silver-Decorated Nitrogen-Doped Multiwalled Carbon Nanotubes

Figure 2

Normalized electrical resistance of nanotube foils exposed to CS₂ vapors at three different operation temperatures for CN_X-MWNTs (black line) and CN_X-MWNTs-Ag (cyan thin line). (a) At 25°C a good performance in both sensor devices is observed; notice that after each purge cycle, the baseline remains constant, suggesting a weak interaction between vapor and sensor material (physisorption). (b) At 40°C, chemisorption and physisorption are both important; both devices still exhibit a good performance. (c) At 80°C the CN_X-MWNTs-Ag still shows better performance than the pristine CN_X-MWNTs device, but now the chemisorption process is the main detection mechanism. Notice that, in all operating temperatures, the CN_X-MWNTs-Ag exhibits larger change in electrical resistance when it is exposed to the CS₂ vapor. The shadow areas indicate the exposure cycles to the CS₂ vapor, equivalent to 80 s.

(a) 25°C

(b) 40°C

(c) 80°C