CN104058459A - Preparation method and purpose of three-dimensional nest like mesoporous structure bismuth tungstate - Google Patents
Preparation method and purpose of three-dimensional nest like mesoporous structure bismuth tungstate Download PDFInfo
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- CN104058459A CN104058459A CN201410283743.4A CN201410283743A CN104058459A CN 104058459 A CN104058459 A CN 104058459A CN 201410283743 A CN201410283743 A CN 201410283743A CN 104058459 A CN104058459 A CN 104058459A
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Abstract
The invention discloses a preparation method and application of a three-dimensional nest like mesoporous structure bismuth tungstate. The gas sensitive material belongs to a bismuth tungstate multistage mesoporous structure system assembled by nanosheets. In a WS-30A static gas-sensitive test system, the gas sensitive material can efficiently and selectively detect ethanol gas in air atmosphere, so as to realize rapid detection of ethanol. The preparation method of the bismuth tungstate gas sensitive material provided by the invention has the advantages of simpleness, high detection efficiency and high selectivity.
Description
Technical field
The present invention relates to inorganic synthesis technical field, relate in particular to a kind of Preparation method and use of three-dimensional nest like meso-hole structure bismuth tungstate.
Background technology
In the mankind's production and life, the detection that detection, monitoring and the resident that ethanol is revealed drives when intoxicated is all very important and requisite for mankind itself's safety of life and property.Equipment for Ethanol in Gas content detection has five kinds of base types in the market, respectively: feulcell prototype (electrochemistry), semi-conductor type, infra red type, gas chromatographic analysis type and compare colour pattern, be subject to price and whether use the effects limit such as convenient, that generally uses only has two kinds of feulcell prototype (electrochemistry type) and semi-conductor types.Semiconductor gas sensor has and is easy to realize the advantages such as integrated, microminiaturized, highly sensitive, low in energy consumption and safe and reliable, is the focus of gas sensor area research.After utilizing gas to be measured to contact with semiconductor surface to be adsorbed, semiconductor gas sensor causes that the change in physical such as semi-conductive specific conductivity carry out detected gas.The conventional semiconductor material of doing semiconductor gas sensor has SnO at present
2, WO
3, ZnO, NiO, MgO, BaTiO
3deng.Research shows, the structure of semiconductor material, pattern, size and specific surface area have remarkably influenced to its absorption property, and semi-conductor is the important factor that affects its air-sensitive performance on the absorption property of gas.Therefore, in the research of semiconductor gas sensor, exploitation has special construction and pattern, specific surface area is large, absorption property is strong and the novel semiconductor material of high response and highly selective is crucial.
Bi
2wO
6the simplest Aurivillius type oxide compound of structure, by (Bi
2o
2)
n 2n+layer and perovskite typed (WO
4)
n 2n-lamella alternately occurs, forms orthohormbic structure.Since last century is over 90 years, people are to Bi
2wO
6technology of preparing carried out systematic study.Traditional preparation method is solid phase method, but product prepared by this method has the shortcomings such as particle diameter is large, size distribution is inhomogeneous, agglomeration is serious conventionally, and preparation process needs high temperature service, energy consumption larger.In order to overcome the shortcoming of solid-phase synthesis, people explore and use the synthetic Bi of some soft chemical methods
2wO
6, as sol-gel method, citric acid method, ultrasonic method, microwave method, hydrothermal method etc., wherein, hydrothermal method is because of its mild condition, is easy to control, easy to operate and in grain-size and morphology control, have the advantage of himself and enjoy favor.In recent years, although people have adopted hydrothermal method to successfully synthesize Bi
2wO
6, but it is synthetic in preparation process, often to adopt morphology control agent to assist, and these additives can be adsorbed on Bi
2wO
6surface and be difficult for removing by simple washing method, high-temperature roasting is easy to again cause Bi
2wO
6subsiding of material structure, affects its pattern and specific surface area, and then affects the performances such as its absorption, catalysis and air-sensitive.
The not yet detection for ethanol as Semiconductor gas sensors material of bismuth tungstate, the main task facing is its efficiency and optionally characterizes.
Summary of the invention
The invention provides a kind of Preparation method and use of three-dimensional nest like meso-hole structure bismuth tungstate.The present invention prepares the three-dimensional nest like meso-hole structure of micron order bismuth tungstate by Hydrothermal Synthesis technology under the condition of not using any template and morphology control agent, without agglomeration, has high-specific surface area and strong absorption property.By modern characterization method (seeing Fig. 1-6), the physicochemical property of material have been carried out to comprehensive sign, and be applied to the rapid detection of ethanol.
The present invention adopts following technical scheme:
The preparation method's of three-dimensional nest like meso-hole structure bismuth tungstate of the present invention concrete steps are as follows:
By Bi (NO
3)
35H
2o is dissolved in HNO
3solution is stirred to solid Bi (NO at 30-50 ℃
3)
35H
2o dissolves, and then adds (NH
4)
10w
12o
415H
2o, with NaOH solution, by the pH regulator of system, be 0.5-2, continue to stir 2h, after stopping stirring, this mixing solutions is proceeded to Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 140-190 ℃, react 10min-12h, after completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 60-100 ℃ of vacuum-drying 1-3h obtains Bi
2wO
6.
HNO
3the concentration of solution is 0.4mol/L, Bi (NO
3)
35H
2o and HNO
3the weightmeasurement ratio of solution is 0.98: 30g/ml.
Preferably at 40 ℃, be stirred to solid Bi (NO
3)
35H
2o dissolves.
(NH
4)
10w
12o
415H
2the add-on of O and Bi (NO
3)
35H
2the weight ratio of O is 25: 98.
With NaOH solution, by the pH regulator of system, be preferably 1.
Preferably by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 2h.
Preferably at 80 ℃ of vacuum-drying 2h, obtain Bi
2wO
6.
Three-dimensional nest like meso-hole structure bismuth tungstate prepared by the present invention can detect for ethanol.
Experiment condition is as follows:
Bi
2wO
6prepare gas sensor: by Bi
2wO
6sample and ethanol are blended in and in mortar, wear into pasty state.Mashed prod is evenly coated in to the outside (vitrified pipe external diameter approximately 1.4 μ m, internal diameter approximately 0.8 μ m, the about 4mm of length) of vitrified pipe, the device coating is treated to ethanol volatilization (the about 0.25mm of thick coating) completely in room temperature is standing.By connecting a pair of Pt wire bond on the Au electrode of vitrified pipe, be connected on base, at the center of vitrified pipe, insert the Ni-Cr B alloy wire of a spring-like and be welded on base simultaneously.The device having welded is inserted on circuit card stand-by in 400 ℃ of heat aging 24h.
During test, the sensor preparing is welded on test card, is then inserted in the slot of test macro.With microsyringe, by the liquid of certain volume, the hole after test system casing is injected into evaporating pan, after liquid evaporation, under the blowing of electric fan, is uniformly dispersed rapidly.Conversion relation in experimentation between the concentration of gas and the volume of required liquid is as follows:
V
1be required liquid system (unit: μ L), V
cthe volume (mL) of test macro casing,
be the concentration (ppm) of test gas, M is the molar mass (gmol of test gas
-1), the purity of liquid that p gets, ρ is the density of got liquid, T
rand T
bbe respectively envrionment temperature and test macro inside temperature (℃).In order to eliminate the impact of water in air steam, when experiment, first in test casing, be filled with dry synthesis of air (N
2/ O
2, V/V, 4: 1) and 10min, and then inject liquid to be tested.
In test atmospheric moisture, during on the affecting of transducer sensitivity, adopt different salt saturated solutions to control relative humidity (LiCl, MgCl
2, Mg (NO
3)
2, KCl and KNO
3) be respectively 11%, 33%, 54%, 75%, 85% and 95%.
Positively effect of the present invention is as follows:
The preparation method of three-dimensional nest like meso-hole structure bismuth tungstate of the present invention has solved Bi
2wO
6in gas sensitive Hydrothermal Synthesis, the difficult removal of morphology control agent waits technical difficulty, and three-dimensional nest like meso-hole structure bismuth tungstate prepared by the present invention, without agglomeration, has high-specific surface area and strong absorption property.Bi prepared by the present invention
2wO
6gas sensitive is highly sensitive, and selectivity is strong, and preparation method is simple, and Bi of the present invention
2wO
6gas sensitive can be for the rapid detection of ethanol.
Accompanying drawing explanation
Fig. 1 is gained Bi under different hydrothermal temperatures
2wO
6the X-ray powder diffraction figure of gas sensitive;
(a)140℃(b)160℃(c)170℃(d)180℃(e)190℃；
As can be seen from Figure 1, when hydrothermal temperature is 140 ℃, the XRD of gained sample is a large diffuse peaks; When 160 ℃ of hydrothermal temperatures, start to have occurred Bi
2wO
6(131), (200), the characteristic diffraction peak of (202) and (331) crystal face; When hydrothermal temperature is 170 ℃, hydro-thermal reaction 2h, the intensity of each diffraction peak continues to strengthen, and the characteristic diffraction peak of (400), (103) and (204) crystal face starts to occur simultaneously; And hydrothermal temperature is while being 190 ℃, reaction 2h, the intensity of each diffraction peak is all stronger, and does not have other assorted peak to occur, and the position of each diffraction peak and fitting like a glove with standard card (JCPDS No.39-0256) illustrates that gained sample is the Bi of pure rhombic system
2wO
6.
Fig. 2 is different hydro-thermal reaction time gained Bi
2wO
6x-ray powder diffraction figure;
(a)10min(b)30min(c)60min(d)2h(e)6h(f)12h；
As can be seen from Figure 2, during 190 ℃ of hydro-thermal reaction 10min, sample is amorphous structure, the diffuse peaks that diffraction peak is broadening; When the reaction times extends to 60min, start to occur the characteristic diffraction peak of (131), (200) (202) and (331) crystal face; When hydro-thermal time lengthening is during to 2h, main characteristic diffraction peak all occurs, and each diffraction peak position and standard card (JCPDS No.39-0256) fits like a glove, and do not occur any impurity phase, the Bi of synthesized when hydro-thermal reaction 2h is described
2wO
6bi for pure rhombic system
2wO
6; Continue to extend the hydro-thermal reaction time to 6h and 12h, the intensity of diffraction peak continues to strengthen, and shows that the degree of crystallinity of sample continues to increase.
Fig. 3 is the Bi of the embodiment of the present invention 2 preparations
2wO
6the x-ray photoelectron energy spectrogram of gas sensitive;
(A) the wide scanning spectrum of XPS (B) Bi4f (C) W4f (D) O1s;
As can be seen from Figure 3A, only contain Bi, W and O element and C element in sample, wherein C element can belong to the C source of pollution of instrument itself; Fig. 3 B-D is respectively the high resolution collection of illustrative plates of Bi4f, W4f and O1s.In Fig. 3 B, feature is in conjunction with can be for 159.2eV is corresponding to Bi4f
7/2, the existence of show+3 valency Bi elements, and in collection of illustrative plates, there is no other oxidation state Bi element; In Fig. 3 C, the Photoelectron peak that W element contains two different-energy positions, in conjunction with being respectively 37.5 and 35.2eV, corresponding W4f
5/2and W4f
7/2energy state, with standard value contrast, can determine that W element is+6 valencys; By Fig. 3 D, can be found out Bi
2wO
6on sample surfaces, the peak of O1s is comparatively complicated, peak is wider and asymmetric, through matching, obtaining three peaks (peak value be respectively 529.29,531.03 and 531.75eV), there is the oxygen of three kinds of combined in interpret sample surface, wherein 529.66 and 531.04eV spectrum peak belong to Bi
2wO
6the two kinds of lattice oxygen characteristic peaks in surface, this and Bi
2wO
6laminate structure relevant; The weak peak at 531.77eV place is corresponding to a small amount of physical adsorption H in surface
2the O1s peak of O.According to the XPS peak area of element, sxemiquantitative calculation result shows, in sample, the atom number ratio of Bi, W, O is about 2: 1.06: 6, further confirms the higher Bi of purity that sample is
2wO
6.
Fig. 4 is the Bi of the embodiment of the present invention 2 preparations
2wO
6the scanning electron microscope (SEM) photograph of gas sensitive and transmission electron microscope picture;
(a) low resolution FE-SEM photo (b-d) high resolution FE-SEM photo (e) TEM and SEAD spectrum (f) high-resolution-ration transmission electric-lens photo (HR-TEM);
As can be seen from Figure 4,190 ℃ of hydro-thermal reaction 2h gained Bi
2wO
6for regular three-dimensional nest like nanostructure, size 3-4 μ m.By high resolution FE-SEM photo (Fig. 4 d)) can find out, the three-dimensional structure of nest like is that the nanometer sheet by many secondary structures assembles, the thickness of secondary nanometer sheet is about 10-20nm; The selected area electron diffraction collection of illustrative plates of sample (Fig. 4 e inserts little figure) shows, Bi
2wO
6nanostructure is typical polycrystalline structure, consist of, and diffraction spot has arcuation spot less nanometer construction unit, and Bi is described
2wO
6nanostucture system may be comprised of single crystal nanoplate.By Fig. 4 f, found out, nanometer sheet interacts and forms Bi
2wO
6nanostucture system.The selected area electron diffraction of single nanometer sheet (in Fig. 4 f, little figure is inserted in the upper left corner), for regular diffraction spot clearly, can be confirmed as single crystal structure.From HR-TEM collection of illustrative plates (Fig. 4 f, little figure is inserted in the lower right corner), can find out, spacing is 0.325nm, this and rhombic system Bi
2wO
6(131) spacing close, consistent with the X-ray powder diffraction analytical results of sample.
Fig. 5 is prepared Bi of different hydro-thermal reaction times at 190 ℃
2wO
6the infrared spectra of gas sensitive;
(a)10min(b)30min(c)60min(d)2h(e)6h(f)12h；
As can be seen from Figure 5, at 3425cm
-1and 1632cm
-1place occurs that the stretching vibration absorption of OH base and formation vibration absorb, and along with the prolongation of hydro-thermal reaction time, absorption peak dies down gradually; At 700-1000cm
-1and 400-600cm
-1within the scope of two, there is serial absorption band, belong to respectively Bi
2wO
6in the stretching vibration (900cm of W-O key
-1the absorption peak at place belongs to not WO on the same group
6the stretching vibration of octahedra W-O end oxygen key, and 750cm
-1the absorption peak at place belongs to the stretching vibration of the W-O key on common summit) and stretching vibration and the flexural vibration of Bi-O key, along with the prolongation of hydro-thermal reaction time, the reduction of the absorption peak strength at this place.
Fig. 6 is Bi prepared by the present invention
2wO
6n
2adsorption-desorption thermoisopleth and pore size distribution curve;
(a)Bi
2WO
6-0.5h(b)Bi
2WO
6-1h(c)Bi
2WO
6-2h(d)Bi
2WO
6-6h；
From Fig. 6 a, can find out, thermoisopleth belongs to typical IV type feature, shows that sample belongs to meso-hole structure material.Sample has different distribution of peaks between 2～100nm, shows hydro-thermal reaction 30min gained Bi
2wO
6mainly with nano spherical particle, form; From Fig. 6 b, can find out, pore size distribution concentrates between 30～100nm, shows the prolongation along with the hydro-thermal reaction time, and in product, sheet structure content is more and more, and the amount of nanoparticle is fewer and feweri; Fig. 6 C is sample Bi
2wO
6the N of-2.0h
2adsorption-desorption thermoisopleth and pore size distribution curve figure, show to have a large amount of sizes to be present in three-dimensional nest like Bi in the hole of 12nm left and right
2wO
6catalyst surface, these holes come from the directed self assembling process of nanometer sheet, the specific surface area (S of sample
bET) pass through N
2adsorption isothermal line (196.68 ℃) calculates, and is approximately 47.72m
2g
-1.Single-point total pore volume is 0.0336cm
3g
-1(specific pressure is P/P
0=0.9854), to have relatively large specific surface area and total pore volume be mainly because sample is meso-hole structure to sample; Sample Bi
2wO
6-0.5h, Bi
2wO
6-1h, Bi
2wO
6the specific surface area of-6h is respectively 25.6,32.6 and 46.5m
2g
-1.
Fig. 7 is Bi prepared by the present invention
2wO
6sensitivity variation with temperature figure;
As seen from the figure, the sensitivity of four kinds of sensors all strengthens along with the rising of working temperature, in the time of 300 ℃ sensitivity the highest, working temperature declines on the contrary higher than 300 ℃ of sensitivity.
Fig. 8 is Bi prepared by the present invention
2wO
6schematic diagram to the response of gas with various;
As seen from the figure, four kinds of sensors all have higher sensitivity to ethanol, lower to Virahol, nonpolar hexanaphthene and sherwood oil sensitivity.
Fig. 9 is Bi prepared by the present invention
2wO
6schematic diagram to the response of different concentration ethanol;
As seen from the figure, along with the increase Bi of alcohol concn
2wO
6response strengthen.When alcohol concn is increased to 100ppm, the mesoporous Bi of nest like
2wO
6(Bi
2wO
6-2h) sensitivity 32.5 of sensor to ethanol, and Bi
2wO
6-6h, Bi
2wO
6-12h, and Bi
2wO
6the sensitivity of-1h based sensor is respectively 15.2,11 and 8.7.
Figure 10 is Bi prepared by the present invention
2wO
6recovery/the response curve of gas sensitive (inserts little figure: response/time of recovery);
As seen from the figure, Bi
2wO
6-2h based sensor has good response/restorability to ethanol.In figure, insert little figure and provided Bi
2wO
6response/the time of recovery of-2h based sensor to ethanol, can find out, when alcohol concn is 5,10,20,50 and during 100ppm, the time of response is respectively 13.5,16.2,22,23.5 and 26.5s.Result shows, the mesoporous Bi of three-dimensional nest like
2wO
6nano material has good air-sensitive performance to ethanol, is a kind of potential gas sensitive.
Figure 11 is the Bi that atmospheric moisture is prepared the present invention
2wO
6the impact of sensitivity;
S
rHresponse value during for specific relative humidity, S
0response value while being 0% for relative humidity;
As seen from the figure, Bi
2wO
6to the response of ethanol, the increase with relative air humidity has all occurred first increasing the trend of falling afterwards based sensor, but relative response intensity is almost constant.This shows, atmospheric moisture is to Bi
2wO
6the impact of sensitivity is not obvious.
Figure 12 is the mesoporous Bi of three-dimensional nest like
2wO
6with mesoporous WO
3sensitivity and recovery/response performance schematic diagram relatively;
As seen from the figure, three-dimensional nest like meso-hole structure Bi
2wO
6the sensitivity of ethanol and response/restorability are all better than to mesoporous WO
3.
Embodiment
The following examples are to describe in further detail of the present invention.
Embodiment 1
By 0.98g Bi (NO
3)
35H
2o is dissolved in the HNO that 30mL concentration is 0.4mol/L
3solution is stirred to solid Bi (NO at the temperature of 40 ℃ of left and right
3)
35H
2o dissolves, and then adds 0.25g (NH
4)
10w
12o
415H
2o, is 1 left and right with NaOH solution by the pH regulator of system, continues to stir 2h.After stopping stirring, this mixing solutions is proceeded to 50mL Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 1h.After completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 80 ℃ of vacuum-drying 2h obtain Bi
2wO
6.
Embodiment 2
By 0.98g Bi (NO
3)
35H
2o is dissolved in the HNO that 30mL concentration is 0.4mol/L
3solution is stirred to solid Bi (NO at the temperature of 40 ℃ of left and right
3)
35H
2o dissolves, and then adds 0.25g (NH
4)
10w
12o
415H
2o, is 1 left and right with NaOH solution by the pH regulator of system, continues to stir 2h.After stopping stirring, this mixing solutions is proceeded to 50mL Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 2h.After completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 80 ℃ of vacuum-drying 2h obtain Bi
2wO
6.
Embodiment 3
By 0.98g Bi (NO
3)
35H
2o is dissolved in the HNO that 30mL concentration is 0.4mol/L
3solution is stirred to solid Bi (NO at the temperature of 40 ℃ of left and right
3)
35H
2o dissolves, and then adds 0.25g (NH
4)
10w
12o
415H
2o, is 1 left and right with NaOH solution by the pH regulator of system, continues to stir 2h.After stopping stirring, this mixing solutions is proceeded to 50mL Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 6h.After completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 80 ℃ of vacuum-drying 2h obtain Bi
2wO
6.
Embodiment 4
By 0.98g Bi (NO
3)
35H
2o is dissolved in the HNO that 30mL concentration is 0.4mol/L
3solution is stirred to solid Bi (NO at the temperature of 40 ℃ of left and right
3)
35H
2o dissolves, and then adds 0.25g (NH
4)
10w
12o
415H
2o, is 1 left and right with NaOH solution by the pH regulator of system, continues to stir 2h.After stopping stirring, this mixing solutions is proceeded to 50mL Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 12h.After completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 80 ℃ of vacuum-drying 2h obtain Bi
2wO
6.
Embodiment 5
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 1h, 2h, 6h, 12h gained Bi at 190 ℃
2wO
6sample is that raw material has been prepared sensor according to method described in summary of the invention, and test gas is 20ppm ethanol, and relative humidity is 0%, has tested its response performance variation with temperature, the results are shown in Figure 7.Result shows, the sensitivity of sensor strengthens along with the rising of working temperature, in the time of 300 ℃ sensitivity the highest, working temperature declines on the contrary higher than 300 ℃ of sensitivity.
Embodiment 6
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 1h, 2h, 6h, 12h gained Bi at 190 ℃
2wO
6sample is that raw material has been prepared sensor according to method described in summary of the invention, 300 ℃ of probe temperatures, relative humidity is 0%, test gas is ethanol, Virahol, hexanaphthene and sherwood oil steam, testing gas concentration is 20ppm, has tested the selectivity of four kinds of sensors to four kinds of gases, the results are shown in Figure 8.Result shows:
Four kinds of sensors all have higher sensitivity to ethanol, lower to Virahol, nonpolar hexanaphthene and sherwood oil sensitivity.
Embodiment 7
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 1h, 2h, 6h, 12h gained Bi at 190 ℃
2wO
6sample is that raw material has been prepared sensor according to method described in summary of the invention, 300 ℃ of probe temperatures, and relative humidity is 0%, test gas is ethanol, has tested the sensitivity of four kinds of sensors to different concentration ethanol, the results are shown in Figure 9.Result shows: when alcohol concn is increased to 100ppm, and the mesoporous Bi of nest like
2wO
6(Bi
2wO
6-2h) sensor is 32.5 to the sensitivity of ethanol, and Bi
2wO
6-6h, Bi
2wO
6-12h, Bi
2wO
6the sensitivity of-1h based sensor is respectively 15.2,11 and 8.7.
Embodiment 8
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 2h gained Bi at 190 ℃
2wO
6sample is that raw material has been prepared sensor according to method described in summary of the invention, 300 ℃ of probe temperatures, and relative humidity is 0%, test gas is ethanol, has tested the response/time of recovery of sensor to different 1-100ppm ethanol, the results are shown in Figure 10.Result shows: when alcohol concn is 5,10,20,50 and during 100ppm, the time of response is respectively 13.5,16.2,22,23.5 and 26.5s.
Embodiment 9
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 1h, 2h, 6h, 12h gained Bi at 190 ℃
2wO
6sample is that raw material has been prepared sensor according to method described in summary of the invention, 300 ℃ of probe temperatures, test gas is 20ppm ethanol, has tested the sensitivity of four kinds of sensors under 0%, 11%, 33%, 54%, 75%, 85% and 95% relative humidity, the results are shown in Figure 11.Result shows: atmospheric moisture is to Bi
2wO
6the impact of based sensor is not obvious.
Comparative example 1
The air-sensitive performance test of sample is carried out in the static air-sensitive test macro of WS-30A.It is 5V that test voltage is set, then voltage (the V of testing sensor in air atmosphere and test gas respectively
h) over time.The sensitivity of sensor (S) is determined by resistance ratio, S=R
a/ R
g, R wherein
afor the resistance of sensor in synthetic dry air, R
gfor the resistance of sensor in test gas.The time of response of sensor is defined as and reaches peak response 90% time used, is defined as response value time of recovery and reduces for 90% time used from maximum.With hydro-thermal reaction 2h gained Bi at 190 ℃
2wO
6sample and WO
3(J.Phys.Chem.C, 2011,115 (37): 18157-18163) sample is that raw material has been prepared sensor according to method described in summary of the invention respectively, 300 ℃ of probe temperatures, relative humidity is 0%, test gas is 20ppm ethanol, has tested two kinds of sensors to the sensitivity of ethanol and response/time of recovery, the results are shown in Figure 12.Result shows: three-dimensional nest like meso-hole structure Bi
2wO
6the sensitivity of ethanol and response/restorability are all better than to mesoporous WO
3.
Although illustrated and described embodiments of the invention, for the ordinary skill in the art, be appreciated that without departing from the principles and spirit of the present invention and can carry out multiple variation, modification, replacement and modification to these embodiment, scope of the present invention is limited by claims and equivalent thereof.
Claims (8)
1. a preparation method for three-dimensional nest like meso-hole structure bismuth tungstate, is characterized in that: the concrete steps of described method are as follows:
By Bi (NO
3)
35H
2o is dissolved in HNO
3solution is stirred to solid Bi (NO at 30-50 ℃
3)
35H
2o dissolves, and then adds (NH
4)
10w
12o
415H
2o, with NaOH solution, by the pH regulator of system, be 0.5-2, continue to stir 2h, after stopping stirring, this mixing solutions is proceeded to Pressure solution bullet, by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 140-190 ℃, react 10min-12h, after completion of the reaction, naturally cool to room temperature, centrifugation, washing is dry, and 60-100 ℃ of vacuum-drying 1-3h obtains Bi
2wO
6.
2. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: HNO
3the concentration of solution is 0.4mol/L, Bi (NO
3)
35H
2o and HNO
3the weightmeasurement ratio of solution is 0.98: 30g/ml.
3. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: at 40 ℃, be stirred to solid Bi (NO
3)
35H
2o dissolves.
4. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: (NH
4)
10w
12o
415H
2the add-on of O and Bi (NO
3)
35H
2the weight ratio of O is 25: 98.
5. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: with NaOH solution, by the pH regulator of system, be 1.
6. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: by putting into electric heating constant-temperature blowing drying box after Pressure solution bullet sealing, at 190 ℃, react 2h.
7. the preparation method of three-dimensional nest like meso-hole structure bismuth tungstate as claimed in claim 1, is characterized in that: 80 ℃ of vacuum-drying 2h obtain Bi
2wO
6.
8. the purposes that the three-dimensional nest like meso-hole structure bismuth tungstate of preparing as claim 1-7 any one detects for ethanol.
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| CN106745265A (en) * | 2016-11-10 | 2017-05-31 | 洛阳理工学院 | A kind of preparation method of bismuth tungstate branch crystal |
| CN109046323A (en) * | 2018-10-18 | 2018-12-21 | 盐城工学院 | A kind of visible light catalyst CQDs/Bi2WO6And its preparation method and application |
| CN111233516A (en) * | 2020-04-01 | 2020-06-05 | 蚌埠学院 | Preparation method and application of oxygen detection sensor material |
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| CN109046323A (en) * | 2018-10-18 | 2018-12-21 | 盐城工学院 | A kind of visible light catalyst CQDs/Bi2WO6And its preparation method and application |
| CN111233516A (en) * | 2020-04-01 | 2020-06-05 | 蚌埠学院 | Preparation method and application of oxygen detection sensor material |
| CN111233516B (en) * | 2020-04-01 | 2022-05-17 | 蚌埠学院 | Preparation method and application of oxygen detection sensor material |
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