Sensing Application — General Synthesis of Mixed Semiconducting Metal Oxide Hollow Spheres with Tunable Compositions for Low-Temperature Chemiresistive Sensing

5 measurement groups · 23 results

Reported values remain attached to the sample, method, conditions, extraction quality and source location that produced them.

Dynamic ethanol response-recovery and concentration-response testing

Quinary MOHS alumina-tube chemiresistive sensor · Electrode

50 ppm ethanol at 80 C for best response/time; additional concentration sweeps 0.5-500 ppm and room-temperature operation.

Temperature: 353
Atmosphere: ethanol in air
Geometry: Alumina-tube chemiresistor
Context: quinary MOHS sensor
Measurement source: p005-p006 / 35064-35065 · Results and discussion · Figure 4c,e; Figure S16

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
Recovery time from 50 ppm ethanol at 80 C	160 s	—	—	Text Exact Reported	p005 / 35064 · Results and discussion · Figure S16a
Response to 50 ppm ethanol at 80 CMarked as a best value within this paper	Rg/Ra = 10.91	—	—	Text Exact Reported	p005 / 35064 · Results and discussion · Figures 4c and S16a
Ethanol response range at 80 C for 0.5-100 ppm	response increased from 1.2 to 11.9 when ethanol increased from 0.5 to 100 ppm	—	—	Text Range	p006 / 35065 · Results and discussion · Figure 4e; Figure S16c
Response time to 50 ppm ethanol at 80 CMarked as a best value within this paper	85 s	—	—	Text Exact Reported	p005 / 35064 · Results and discussion · Figure S16a
Optimised operating temperatureMarked as a best value within this paper	80 C	353.15 K	—	Text Exact Reported	p005 / 35064 · Results and discussion · Figure 4c
Room-temperature ethanol response range	response increased from 1.71 to 4.86 as ethanol increased from 10 to 500 ppm at 25 C	—	—	Text Range	p006 / 35065 · Results and discussion · Figure 4e
Table S3 benchmark response for this workMarked as a best value within this paper	10.91 at 80 C and 50 ppm ethanol	—	—	SI Table Exact Reported	S-25 · Table S3 · Table S3

Chemiresistive gas sensing on MA1.0 system

Quinary MOHS alumina-tube chemiresistive sensor · Electrode

Circuit voltage 5 V; resistance in air and target gas monitored in real time; response defined as Rg/Ra for p-type and Ra/Rg for n-type semiconductor.

Atmosphere: air/target gas switching; ethanol, methanol, formaldehyde, toluene, methane and hydrogen
Geometry: Alumina tube with Au electrodes and Ni-Cr heater wire
Context: quinary MOHS sensor
Measurement source: S-3 to S-4 · 1.5 Gas sensing performance

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
P-type chemiresistive behaviour	Output resistance increased when ethanol was injected, indicating p-type semiconductor gas-sensor behaviour.	—	—	Text Qualitative	p005 / 35064 · Results and discussion · Figure 4b; Figure S15

Selectivity test against interfering gases

Quinary MOHS alumina-tube chemiresistive sensor · Electrode

50 ppm ethanol, methanol, formaldehyde, toluene, methane and hydrogen at 80 C.

Temperature: 353
Atmosphere: individual VOC/gas exposures in air
Geometry: Alumina-tube chemiresistor
Context: quinary MOHS sensor
Measurement source: p006 / 35065 · Results and discussion · Figure S16d,e

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
Selectivity response to ethanolMarked as a best value within this paper	10.91	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e
Selectivity response to formaldehyde	2.35	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e
Selectivity response to hydrogen	1.05	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e
Selectivity response to methane	1.1	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e
Selectivity response to methanol	4.20	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e
Selectivity response to toluene	1.27	—	—	Text Exact Reported	p006 / 35065 · Results and discussion · Figure S16e

Long-term stability and humidity dependence of ethanol sensing

Quinary MOHS alumina-tube chemiresistive sensor · Electrode

50 ppm ethanol; stability over 4 weeks; humidity tests at about 40%, 65% and 90% RH.

Temperature: 353
Atmosphere: ethanol in humid air
Geometry: Alumina-tube chemiresistor
Context: quinary MOHS sensor
Measurement source: S-21 to S-22 · Figures S17 and S18 · Figures S17, S18

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
Ethanol response at about 40% RH	9.69 at ~40% RH	—	—	Caption Exact Reported	S-22 · Figure S18 · Figure S18
Ethanol response at about 65% RH	10.37 at ~65% RH	—	—	Caption Exact Reported	S-22 · Figure S18 · Figure S18
Ethanol response at about 90% RH	10.61 at ~90% RH	—	—	Caption Exact Reported	S-22 · Figure S18 · Figure S18
Long-term ethanol response retention after 4 weeks	~94.0%	—	—	Text Approximate	p006 / 35065 · Results and discussion · Figure S17

Comparative ethanol sensing response of quinary MOHS and unitary oxide sensors

Unitary metal oxide control sensors · Electrode

50 ppm ethanol at 25 and 80 C; bar chart read visually for control oxides.

Temperature: 298 and 353
Atmosphere: ethanol in air
Geometry: not fully specified for controls
Context: unitary oxide pristine controls compared with quinary mixed oxide
Measurement source: p005 / 35064 · Results and discussion · Figure 4d

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
Co3O4 control response at 80 C	approximately 9 response units from Figure 4d	—	visual estimate	Visual Estimate Approximate	p005 / 35064 · Figure 4d · Figure 4d
CuO control response at 80 C	approximately 6.3 response units from Figure 4d	—	visual estimate	Visual Estimate Approximate	p005 / 35064 · Figure 4d · Figure 4d
Fe2O3 control response at 80 C	no response	—	—	Figure Axis Qualitative	p005 / 35064 · Figure 4d · Figure 4d
NiO control response at 80 C	approximately 3.4 response units from Figure 4d	—	visual estimate	Visual Estimate Approximate	p005 / 35064 · Figure 4d · Figure 4d
ZnO control response at 80 C	approximately 1.8 response units from Figure 4d	—	visual estimate	Visual Estimate Approximate	p005 / 35064 · Figure 4d · Figure 4d