Carbon Nanotubes as Active Components for Gas Sensors

Table 4

Summary of sensing performance of metal oxide functionalized CNT sensors. (Note: N/S = Not-stated.)

Metal oxide	CNT type	Sensor configuration	Targeted analytes	Detection limit	Response time	Recovery time	Reference
SnO2	SWCNTs	Resistor	NO2	N/S	9 min	1.5 min	[65]
SnO2	SWCNTs	Resistor	H2	300 ppm	2–5 s (200–250^∘C)	3–5 s (200–250^∘C)	[66]
SnO2	SWCNTs	Resistor	NH3	10 ppm	∼100 s	∼3.2 min	[67]
SnO2	MWCNTs	Resistor	LPG, C2H5OH	10 ppm	N/S	N/S	[68]
SnO2	MWCNTs	Resistor	C2H5OH	10 ppm	∼1 s (300^∘C)	∼10 s (300^∘C)	[69]
SnO2	MWCNTs	Resistor	NO2	100 ppb	N/S	20 min (150^∘C)	[70]
SnO2	MWCNTs	Resistor	NH3	60 ppm	<5 min	<5 min	[71]
SnO2	MWCNTs	Resistor	formaldehyde	0.03 ppm	100 s (250^∘C)	90 s (250^∘C)	[72]
WO3	MWCNTs	Resistor	NO2, CO, NH3	500 ppb NO2, 10 ppm CO, 10 ppm NH3	N/S	N/S	[73]
TiO2	MWCNTs	Resistor	acetone, NH3	N/S	10–40 s (acetone)	10–300 s (acetone)	[74]
TiO2	CNTs	Resistor	O2	10 ppm	5–8 min (350–550^∘C)	∼20 min (350^∘C)	[75]
SnO2, TiO2	SWCNTs, MWCNTs	Resistor	C2H5OH	100 ppm	<10 s (210–400^∘C)	<10 s (210–400^∘C)	[76]