Carbon Nanostructure-based Sensors: A Brief Review on Recent Advances

Table 1

Comparison between discussed gas sensor responses and different systems found in the literature.

Sensor compound or device	Sensitivity/linear range/LOD	Great response for	Other reported systems	Responses from other systems
Bilayer GPN [47]	12.87% at 5 ppm (RT) and 1.409 ppm^−1	NO2	Monolayer and multilayer (0.696 ppm^−1 and 0.498 ppm^−1) [47]	Less than 10% at 5 ppm and 0.5 ppm^−1 (GPN-based sensors)
Superhydrophobic rGO [49]	93% at 1 ppm (at 140°C) and 25.5 ppm^−1	NO2	3D-rGO [63]	NR
GPN-V2O5 [42]	12.0% at 1 ppm (RT) and 26.0% at 20 ppm (RT)	NO2 and NH3	Exfoliated Gr [64]; SiC/Gr + Au [65]; defective CVD Gr [66, 67]; B-doped CVD Gr [68]	4% to 55% in the range from 0.02 ppm to 200 ppm
SnO2 QDs-C60 [52]	66.0 (Ra/Rg) at 70 ppm (at 150°C)	H2S	SnO2 QW/rGO [69]	33.0 at 50 ppm (at RT);
			SnO2 NFs/rGO [70]	33.7 at 5 ppm (at 200°C)
			SnO2 multitube arrays [71]	1.45 at 5 ppm (at RT)
Li^+/CNT [54]	14.5% at 500 ppm	CH4	Unmodified CNT sensor [54]	4.8% at 500 ppm (at RT)
GCNTs/Pt	42.8% at 4% H2 in air	H2	Pt/CNTs [72–74]; Pd/CNTs [75]; Pt-Pd/CNTs [76]; Pd/CNT/rGO [77]	2% to 35% in the range 1% to 4% of H2
CNT onto glass subs. Between Pd electrodes [56]	208% to 359% in the range 20 ppm to 1,000 ppm (100°C)	H2	Single and multiwalled CNT [78–81]	0.58% to 200% in the range 100 ppm to 80,000 ppm

RT = room temperature. (R_a/R_g) = R_a is the resistance of gas sensors in the reference gas (usually the air) and R_g is the resistance in the reference gas containing target gases. NR = not reported.