Journal of Sensors / 2009 / Article / Tab 3 / Review Article
Conductometric Gas Nanosensors Table 3 A summary of SnO2 based nanosensor properties and performances. Sensors generally show high responses and often work at RT. In several cases, some sort of conditioning process is adopted to improve device characteristics.
Material Chemical species (carrier) Range Recovery Conditioning notes Ref. SnO2 nanoribbons NO2 (synthetic air) 3 ppm Yes, few seconds by UV irradiation Yes Reversible at RT. Photoinduced desorption of the analyte [94 ] SnO2 nanobelts NO2 (synthetic air) few ppb Yes Yes Operating temperature is 400°C. CO and ethanol increase the conductivity, while NO2 decreases the conductivity, of the SnO2 nanobelts [95 ] SnO2 nanowires CO (dry air) few hd ppm Yes Yes CO increases the conductivity with response times of
30 s at 300°C [96 ] SnO2 nanopowders C2 H5 OH ( air) 50–200 ppm Yes Yes Annealing at 600°C [97 ] Single SnO2 nanobelts H2 2% H2 Yes Yes Operating temperatures between 25°C and 80°C. Resistance decreases with response time <220 s; power cons. <10 nW @ 25°C [98 ] SnO2 –In2 O3 nanocomposite oxides CO (air) Sensitivity of 16.0 and 7.5 to CO and NO2 , respectively NA Yes Nanocomposites calcined at 600°C. Sensitivity increases with gas concentration at 100°C–300°C [99 ] NO2 (air) SnO2 /Fe2 O3 nanocomposites CO CO (40–150 ppm), NA Yes Temperature range: 150°C–450°C. Increasing of Fe2 O3 content results in oxidation enhancement. [100 ] ethanol ethanol (10–200 ppm), H2 S NO2 H2 S (2–10 ppm) (RH 30%) NO2 (50 ppb–10 ppm) SnO2 /MoO3 nanostructure Cn 2n +1 OH (
–4); NH3 in air 1
l alcohols (300°C); 500 ppm NH3 (350°C) NA Yes Electric sensor response to the alcohols decreases with increasing MoO3 content [101 ] single SnO2 nanowire RH 5%–85% RH Yes Yes Pt boxes deposited by focused ion beam (FIB) improve electrode contact. R decreases with the increase of RH in air at 30°C [102 ]
