Table 7.

Some sensing properties of composite and heterostructure-based electrospun metal oxide NFs.

Material	Gas	Conc. (ppm)	T, (°C)	Response (Ra/Rg)	Ref.
TiO2–ZnO	O2	10,000	300	20	[295]
ZnO–rGO	NO2	5	400	119	[79]
p-In2O3–TiO2	NOx	97	25	40	[296]
Al2O3–In2O3		97	25	100	[254]
CuO–In2O3	H2S	5	RT	9170	[297]
CuO-SnO2		10	300	25799	[170]
ZnO–CuO		10	150	4490	[298]
SnO2–CeO2		20	210	90	[240]
CuO–ZnO	CO	0.1	300	7	[299]
SnO2–RGO		1	200	10	[300]
TiO2–ZnO		0.1	375	15	[301]
SnO2–ZnO		10	350	11	[302]
SnO2–MWCNT		50	25	1.3	[303]
p-NiO–n-SnO2	H2	100	320	13	[304]
In2-xNixO3	C2H5OH	100	180	80	[305]
Cr2O3–ZnO		100	300	24	[116]
In2O3–ZnO		100	210	25	[306]
ZnO–In2O3–ZnO		100	210	17	[306]
Sn-SnO2–Carbon		500	240	30	[307]
ZnO-TiO2		500	320	51	[258]
SnO2–ZnO	CH3OH	10	350	8.5	[308]
In2O3–WO3	C3H6O	0.8	350	1.8	[252]
SnO2–α-Fe2O3		100	340	31	[309]
In2O3–WO3		0.4	275	1.3	[252]
α-Fe2O3–NiO	CH2O	50	240	13	[255]
NiO–SnO2		10	200	6.3	[310]
SnO2–In2O3		0.5	375	2.2	[311]
SnO2–In2O3		50	300	115	[257]
PPy–WO3	NH3	20	100	26	[312]
SnO2–In2O3		1	25	21	[261]
PANI–TiO2		0.025	25	0.4	[313]
p-La0.67Sr0.33MnO3–n-CeO2	C3H8	20	800	75	[238]
NiO-SnO2	C7H8	50	330	11	[314]
La0.7Sr0.3FeO3–In2O3-SnO2	C3H9N	1	80	8	[315]
p-NiO–n-ZnO		100	260	892	[316]
ZnO–In2O3		5	375	119	[317]

C₃H₆O—acetone; C₂H₅OH—ethanol; CH₂O—formaldehyde; C₃H₈—propane; CH₃OH—methanol; C₇H₈—toluene; C₃H₉N—trimethylamine; PPy—polypyrrole; PANI—polyaniline; rGO—reduced graphene oxide.