. 2019 Jan 9;19(2):233. doi: 10.3390/s19020233

Table 3.

Summary of the gas-sensing performances of semiconductor metal oxides for acetone gas.

Order	Dimensions	Materials	Synthesis Method	Conc. (ppm)	LOD (ppm)	Temp. (°C)	τ_res (s)	τ_rec (s)	Resp.	Ref.
1	0D	Au/ZnO nanoparticles	MOF template	10	0.05	280	15	12	43 ^a	[129]
2		Ce/CoFe₂O₄ nanocrystallites	molten-salt	2000	NA	200	38	61	157 ^b	[130]
3		Fe₂O₃ nanoparticles	hard template	100	NA	300	6	NA	26.3 ^a	[131]
4		Pt/In₂O₃ nanoparticles	sol-gel	1.56	0.01	200	25	120	12 ^a	[132]
5		ZnFe₂O₄ nanoparticles	hydrothermal	200	NA	200	NA	NA	39.5 ^a	[133]
6		LaFeO₃ powders	sol-gel method	10	NA	200	21	6	7.83 ^b	[134]
7	1D	Co₃O₄ nanochains	solution route	200	5	180	32	35	10.5 ^b	[135]
8		Fe₂O₃ nanorods	interfacial-reaction	100	NA	280	0.4	2.4	32.5 ^a	[136]
9		ZnFe₂O₄ nanorods	hydrothermal	100	NA	260	1	11	52.8 ^a	[137]
10		Fe₂O₃ nanotubes	electrospinning	100	NA	240	9	3	11 ^a	[138]
11	2D	Co₃O₄ nanosheets	fluorine-assisted hydrothermal	1000	NA	111	NA	NA	36.5 ^b	[139]
12		ZnO nanosheets	precipitation	200	0.81	300	18.71	13.75	106.1 ^a	[78]
13		In₂O₃ films	sparking process	2000	NA	350	3	NA	117 ^a	[140]
14		ZnO films	sol-gel dip coating	50	2	RT	60	28	490 ^a	[141]
15		ZnO films	e-beam and post-annealing	100	10	280	6	18	30 ^a	[9]
16	3D	Fe₂O₃ microflowers	hydrothermal	100	NA	220	8	19	52 ^a	[142]
17		SnO₂ nanoflowers	hydrothermal	50	NA	170	3	28	29.2 ^a	[143]
18		ZnO nanoflowers	hydrothermal	100	NA	300	7	NA	18.6 ^a	[144]
19		ZnFe₂O₄/ZnO microflowers	solution route	50	1	250	2	25	8.3 ^a	[145]
20		ZnO porous flowers	hydrothermal	50	0.25	280	2	23	97.8 ^a	[146]
21		LaFeO₃ microspheres	hydrothermal	100	1	225	5	25	25.5 ^b	[147]
22		Au/In₂O₃ nanospheres	hydrothermal	10	NA	320	4	9	53.08 ^b	[148]
23		LaFeO₃ microspheres	hydrothermal	100	NA	260	9	17	29 ^b	[149]
24		SnO₂/Fe₂O₃ nanospheres	self-sacrificial template	100	NA	260	3	6	47.1 ^a	[150]
25		ZnFe₂O₄ nanospheres	solvothermal	30	0.8	200	9	272	11.8 ^a	[151]
26		ZnFe₂O₄ microspheres	solvothermal	50	0. 5	200	NA	NA	28.3 ^a	[152]
27		ZnFe₂O₄ microspheres	hydrothermal	20	0.13	206	NA	NA	13.6 ^a	[153]
28		ZnO/ZnFe₂O₄ microspheres	self-sacrificial template	20	NA	140	5.2	12.8	5.9 ^a	[154]
29		SnO₂ hierarchical structures	hydrothermal	100	0.05	325	NA	NA	175 ^a	[155]
30		ZnO macro-mesoporous structures	layer-by-layer filtration deposition	100	NA	260	13	50	137 ^a	[156]
31		ZnO urchin-like structures	hydrothermal	10	NA	300	42	10	58.1 ^a	[157]
32		ZnO/ZnFe₂O₄ microcubes	MOF template	5	0.5	250	5.6 min	6.0 min	9.4 ^a	[158]
33		ZnFe₂O₄ octahedral nanocages	thermal decomposition	200	NA	120	NA	NA	64.4 ^a	[159]
34		ZnO/ZnFe₂O₄ nanocages	self-sacrificial template	100	1	290	8	32	25.8 ^a	[160]

Note: Conc. = concentration; LOD = limit of detection; Temp. = temperature; τ_res = response time; τ_cov = recovery time; Resp. = Response; Ref. = References; RT = room temperature; ^a S = R_a/R_g; ^b S = R_g/R_a; ^c S = (ΔR/R_a)*100%; ^d S = I_g/I_a; NA = not available.