Carbon Nanotubes as Active Components for Gas Sensors

Table 3

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

Metal	CNT type	Sensor configuration	Targeted analytes	Detection limit	Response time	Recovery time	Reference
Pd	S-SWCNT	FET	H2	<40 ppm	5–10 s (for half resistance change)	400 s	[49]
Pd	SWCNTs	Resistor	H2	1000 ppm	N/S	N/S	[50]
Pd	SWCNTs	Resistor	H2	100 ppm	10 min	20 min	[51]
Pd	SWCNTs	Resistor	H2	100 ppm	3–60 s (for 36.8% resistance change)	∼5 min	[52]
Pd	SWCNTs	Resistor	H2	∼10 ppm	<10 min	<30 s	[53]
Pd	ACNTs	Resistor	H2	100 ppm	<7 min	N/S	[54]
Pd	SWCNTs	Resistor	CH4	6 ppm	2–4 min	N/S	[55]
Pd	MWCNTs	Resistor	CH4	2%	∼310 s	∼176 s	[56]
Pt	MWCNTs	Resistor	H2	N/S	10 min	15 min	[57]
Pd	MWCNTs	Resistor	H2	N/S	7 min	7 min	[58]
Pt	MWCNTs	Resistor	H2, NO2, H2O	N/S	∼10 min	∼14 min	[59]
Au	SWCNTs	Resistor	NH3, NO2	<120 ppb NH3	150 s	200 s	[60]
Au, Pt	MWCNTs	Resistor	NO2, NH3	100 ppb NO2, 5 ppm NH3	N/S	N/S	[61]
Au, Ag	MWCNTs	Resistor	NO2	500 ppb NO2	∼20 min	N/S	[62]
Pt, Pd, Sn, Rh	SWCNTs	FET	H2, CH4, CO, H2S	N/S	∼5 min	N/S	[63]
Pd, Au	SWCNTs	Resistor	NO2, HCN, HCl, Cl2, acetone, benzene	5 ppm	N/S	N/S	[64]