Table 5.

Summary of the gas sensing properties of 1-D SnO₂ nanostructures for different gases.

Gas Tested	Morphology	Size		Detection Range	Detection Temperature (°C)	Optimum Working Temperature (°C)	Response			Response Time	Recovery Time	Reference
		Diameter	Length				Sensitivity	Concentration	Temperature (°C)
Ethanol	Nanowhisker	50–200 nm	Tens of micrometers	50 ppm	300	–	23 A	50 ppm	300	–	10 min	[28]
	Nanorod (flowerlike)	5–20 nm	100–200 nm	10–1,000 ppm	200, 300	200	45.1 A	100 ppm	200	–	–	[64]
	Nanorods (flowerlike loaded with La2O3)	5–20 nm	100–200 nm	10–1,000 ppm	200, 300	200	213 A	100 ppm	200	–	–	[64]
	Nanofiber (Pd doped)	200–300 nm	Tens of micrometers	100 ppm	330–440	330	1,020.6 A	100 ppm	330	<10 s	503 s for 100 ppm at 385 °C	[65]
H2S	Nanofiber	200–300 nm	–	4–20 ppm	300–500	300	121 A	20 ppm	300	2–7 s	267–281 sfor 200 ppmat 400 °C	[56]
	Nanofiber (Pt doped)	200–300 nm	–	4–20 ppm	300–500	300	5,100 A	20 ppm	300	1 s	214–267 sfor 200 ppmat 400 °C	[56]
	Nanoribbon (loaded with CuO nanoparticles)	20–200 nm	Order of millimeters	3 ppm	27–200	50	18,000 A	3 ppm	50	–	–	[27]
H2	Nanobelts	80 nm (thickness)	330 nm (width)	2%	25–80	–	60% C	2%	25	220 sat 25 °C	220 s at 25 °C	[74]
NH3	Nanowire	60 nm	–	300–1,000 ppm	50–300	200	11 A	1,000 ppm	200	–	–	[10]
	Nanowire (hierarchical)	60 nm	–	300–1,000 ppm	50–300	200	21.7 A	1,000 ppm	200	–	–	[68]
LPG	Nanowire	60 nm	–	500–2,000 ppm	50–450	350	5.8 A	2,000 ppm	350	<10 s at 350 °C	<10 s at350 °C	[10]
	Nanowire (hierarchical)	60 nm	–	500–2,000 ppm	50–450	350	20.4 A	2,000 ppm	350	–	–	[68]
Toluene	Nanofiber	80–160 nm	–	10–10,000 ppm	310–380	350	6 A	100 ppm	350	1 s	5 s	[13]
Acetone	Nanorod	20–70 nm	1 μm	1–100 ppm	450	450	3.7 A	10 ppm	450	–	–	[16]
Triethylamine	Nanorod	20–70 nm	1 μm	1–100 ppm	350	350	64.8 A	50 ppm	350	<10 s	<10 s	[16]
NO2	Nanofiber (SnO2-ZnO composite)	55–80 nm	–	0.4–3.2 ppm	150–300	180–200	105 B	3.2 ppm	200	–	–	[67]

Note: ^A S = R_a/R_g, ^B S = R_g /R_a, and ^C S = (ΔR/R_g) × 100%.