CN110255621B - WO (WO)3Preparation of nanoflower material and application of nanoflower material in gas sensor - Google Patents
WO (WO)3Preparation of nanoflower material and application of nanoflower material in gas sensor Download PDFInfo
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Abstract
The present invention provides a WO3Preparation of a nanoflower material and application of the nanoflower material in a gas sensor. Extracting tungsten in the scheelite concentrate by adopting a NaOH leaching process to obtain a tungsten-containing leaching solution; adding the leachate into HCl solution to form tungstic acid precipitate, adding the washed tungstic acid into deionized water and H2O2Dissolving; adjusting the pH value of the mixed solution to 1.2-1.8 by using HCl solution, and reacting for 4-16 h at constant temperature of 100-180 ℃ to obtain WO formed by self-assembling nano sheets3The nanometer flower is 300-420 nm in diameter and 100-140 nm in thickness, the nanometer sheet is 170-390 nm in length, 120-140 nm in width and 30-50 nm in thickness, and has a hexagonal crystal structure. This WO is incorporated in3The nanoflower is coated on a gold electrode on the outer surface of the ceramic tube, and then the gas sensor is prepared through aging treatment. Preparation of NO based on the Process of the invention2Gas sensor capable of realizing low concentration, even ppb level NO2High selectivity of gas, fast response at low operating temperature.
Description
Technical Field
The invention relates to the technical field of gas sensors of semiconductor oxides, in particular to a method for synthesizing WO (tungsten oxide) self-assembled by nano sheets by using scheelite concentrate3A method of nanoflower and its use in gas sensors.
Background
With the rapid development of science and technology and the continuous acceleration of industrialization in China, more and more flammable and combustible or toxic and harmful gases are discharged into the air to cause serious environmental pollution, even fire, explosion and the like can be caused in the production and use processes of products in the fields of coal, petroleum, chemical industry, automobiles, mining and the like, and the health and the safety of human beings are seriously threatened. Wherein nitrogen dioxide (NO)2) The gas is a common strong toxic gas with pungent odor, and mainly comes from high-temperature combustion of some fossil fuels, emission of motor vehicles and the like. It is not only the main cause of acid rain, but also causes a series of environmental problems such as ozone layer thinning, land acidification, surface water eutrophication and the like. At the same time, NO2It also can damage the respiratory system of human body, seriously endanger human health, and damage the respiratory system of human body at quite low concentration. Therefore, in order to effectively protect the environment and human safety, it is urgently needed to develop a NO suitable for low concentration detection and with good selectivity2A gas sensor.
WO3Is the most common metal oxide functional material with wide application, has excellent gas-sensitive, catalytic and photoelectric properties, is widely applied to the fields of gas sensors, catalysts, photoelectrolysis and the like, and can be used for NO2、NH3、H2The detection of gases such as acetone, ethanol, toluene and the like has great application prospect, and therefore, the method is widely used in the aspects of mine safety, environmental detection, factory safety monitoring and the like. In the prior art preparation of WO3In many researches on nano materials, sodium tungstate, ammonium metatungstate, tungstic acid and hexachloro are selectedAs a tungsten source, an analytically pure reagent such as tungsten oxide or extremely high purity tungsten metal is expensive and has a certain polluting property.
Disclosure of Invention
Aiming at the prior preparation of functional WO3The invention takes the scheelite concentrate as the tungsten source to prepare the WO self-assembled by nano sheets3Nanometer flower, breaks through the functional WO with high added value3The limitation of the source of raw materials. With WO3The gas sensor prepared by taking the nanoflower as the gas sensitive material can realize the control of low concentration, even ppb level NO at lower working temperature2The detection is effective. The technical scheme is as follows:
the invention provides a WO self-assembled by nano sheets3A nanoflower material, said WO3The diameter of the nanoflower material is 300-420 nm, the thickness of the nanoflower material is 100-140 nm, the length of the nanosheet is 170-390 nm, the width of the nanosheet is 120-140 nm, the thickness of the nanosheet is 30-50 nm, and the nanosheet is of a hexagonal phase crystal structure.
In another aspect of the present invention, there is provided the above-mentioned WO3A method for preparing a nanoflower material, the method comprising the steps of:
putting the scheelite concentrate into a NaOH solution with the concentration of 15-18 mol/L, leaching under the experimental conditions that the liquid-solid ratio is 1: 1-3: 1, preferably 1:1, the reaction temperature is 170-190 ℃, preferably 180 ℃, the stirring speed is 400-700 rpm, and the heat preservation time is 30-180 min, filtering the obtained leaching product to obtain filtrate and leaching residues, washing the leaching residues with deionized water for 3 times to obtain washing liquid, and mixing the obtained filtrate and the obtained washing liquid to obtain a leaching solution containing tungstate ions, wherein the concentration of W in the leaching solution is 50-200 g/L, preferably 122.2 g/L;
and secondly, taking out the leachate obtained in the step ①, adding the leachate into an HCl solution, and magnetically stirring for 2-5 min to obtain a white tungstic acid precipitate, wherein the concentration of the HCl solution is 2-4 mol/L, and the volume ratio of the leachate to the HCl solution is 1: 2-1: 5.
thirdly, the white pigment obtained in the step ②Washing the chromotungstic acid precipitate with deionized water, centrifuging for 5 times to obtain a clean tungstic acid product, adding deionized water into the tungstic acid product, wherein the using amount ratio of the volume (mL) of the deionized water to the mass (g) of tungsten in the tungstic acid product is 50-120, and then adding 30% H2O2W element and H in the tungstic acid product2O2The mass ratio of (A) is 0.8-1.2, the mixture is magnetically stirred for 10-20 min at 20-30 ℃, then the pH value of the mixed solution is adjusted to 1.2-1.8 by using an HCl solution with the concentration of 2-4 mol/L, and after the solution is magnetically stirred for 10-20 min at 20-30 ℃, the solution is subjected to hydrothermal reaction for 4-16 h at the constant temperature of 100-180 ℃ to obtain a white precipitate;
fourthly, washing, drying and heat treating the white precipitate obtained in the step ③ to obtain the WO self-assembled by the nano sheets3And (4) nano flowers.
Preferably, the grade of the scheelite concentrate is 62.36%. The grade of the scheelite concentrate in the invention refers to the percentage content of tungsten in the scheelite concentrate.
preferably, the washing and drying processes in the step ④ includes washing the white precipitate for 5-6 times, drying for 12-24 h at 60-80 ℃, and then heat treating the dried product for 4-8 h at 400-500 ℃.
The invention further provides a method for synthesizing WO self-assembled by nano sheets by using the scheelite concentrate3Gas-sensitive coating of nanoflower material.
The invention also provides a gas sensor comprising the gas-sensitive coating, and the preparation method of the gas sensor comprises the following steps:
the WO self-assembled by the nano sheets3Adding the nanoflower into absolute ethyl alcohol, and performing ultrasonic dispersion to obtain viscous slurry; uniformly brushing the viscous slurry on the gold electrode and Al2O3Preparing a gas-sensitive coating on the outer surface of the ceramic tube, and naturally drying for 10-30 min; Ni-Cr heating wires are transversely penetrated through Al2O3A ceramic tube, both ends of which are welded to the heating electrode; connecting the gold electrode with a platinum wire, welding the platinum wire on the measuring electrode to obtain a gas sensor, and placing the gas sensor on an aging table at 30 deg.CAging for 24-72 h at 0 ℃.
The WO self-assembled by nano sheets3The nanometer flower gas-sensitive material and the heat treatment and aging treatment of the gas-sensitive element aim at keeping the structure of the gas-sensitive material and the stability of the performance of the gas-sensitive element.
The invention also provides NO2The gas sensor comprises the gas sensitive element, and the gas sensitive element is used for detecting NO2The detection range of the gas concentration is 50 ppb-5 ppm.
According to the method, the scheelite concentrate with the grade of 62.36% is taken as a tungsten source, the tungsten in the scheelite concentrate is extracted by adopting a sodium hydroxide leaching process to obtain a leachate containing tungstate ions, and then the leachate is taken as a precursor to synthesize the WO self-assembled by nanosheets by adopting a one-step hydrothermal method3Nanoflowers and use of these WO3The NO prepared by the nanoflower has the advantages of low working temperature, good reversibility, high response/recovery speed, good selectivity and the like2A gas sensor element. WO prepared according to the invention3The nanoflower gas sensor can realize low-concentration even ppb level NO at lower working temperature2The method has good application prospect.
Advantageous effects
(1) The invention takes the scheelite concentrate as a tungsten source, adopts a sodium hydroxide leaching process to obtain a leachate containing tungstate radicals, and adopts the leachate as a precursor to prepare the WO with good crystallization, large specific surface area and high porosity, which is self-assembled by nano sheets and prepared by a simple one-step hydrothermal method3A nanoflower; then self-assembling the WO formed by the nano-sheets3After the nanoflower is subjected to heat treatment in a tube furnace, WO is prepared on the ceramic electrode3The nano flower gas-sensitive coating is finally subjected to heat treatment by an aging table to obtain the WO-based gas-sensitive coating3NO of nanoflower2A gas sensor. The gas sensor can obtain 5ppm NO at 100 DEG C2The maximum sensitivity of the gas is 36.07, the response time and the recovery time are respectively 18s and 338s, the reversibility and the selectivity are good, the response/recovery speed is high, and the problem of the traditional NO is effectively solved2Gas sensor operating at low temperaturesTo low concentration of NO2The gas-sensitive property is poor, and the NO has good development prospect2A gas sensor.
(2) The preparation method of the invention takes the selection of raw materials as a starting point, adopts the scheelite concentrate with low price and low pollution as a tungsten source, and greatly reduces the functional WO3The preparation cost of the nano material.
Drawings
FIG. 1 is an X-ray diffraction diagram of a scheelite concentrate used in example 1;
FIG. 2 is a schematic view of gas sensors in examples 1 to 3; wherein: al (Al)2O3A ceramic tube 1; a Ni-Cr heater wire 2; a gold electrode 3; a platinum wire 4; a gas-sensitive coating 5;
FIG. 3 is a WO self-assembled from nanoplates prepared in example 13An X-ray diffraction pattern of the nanoflower;
FIG. 4 is a WO self-assembled from nanoplates prepared in example 13Scanning electron microscope images of the nanoflower at low magnification and at high magnification;
FIG. 5 is a graph of the gas sensor of example 1 for 5ppm NO at different operating temperatures2A dynamic response profile of the gas;
FIG. 6 is a graph of gas sensor pair of example 1 for 5ppm NO2A graph of sensitivity of the gas versus operating temperature;
FIG. 7 shows the gas sensor of example 1 for 5ppm NO at different operating temperatures2Response and recovery time profiles of the gas;
FIG. 8 shows the gas sensor of example 1 for different concentrations of NO at an operating temperature of 100 deg.C2A dynamic response profile of the gas;
FIG. 9 shows the sensitivity of the gas sensor of example 1 at an operating temperature of 100 ℃ in comparison with NO2A graph of the relationship between gas concentrations;
FIG. 10 is a graph of the gas sensor of example 1 for 5ppm NO at 100 deg.C2A reproducibility plot of the gas;
FIG. 11 is a graph showing the selectivity of the gas sensor of example 1 for different gases at an operating temperature of 100 ℃;
Detailed Description
The scheelite concentrate adopted in the invention is provided by Gansu Xinzhou mining industry Co., Ltd, and is obtained from small tungstic ore of Gansu province Zhangye City, Nancounty, Gansu province, with the grade of 62.36%.
The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The test methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.
Example 1
The invention relates to a method for synthesizing WO self-assembled by nano sheets by using scheelite concentrate3Method for producing nanoflower and its use in NO2Application in gas sensors. The X-ray diffraction pattern of the white tungsten concentrate adopted by the invention is shown in figure 1, and the result shows that the main useful mineral in the white tungsten concentrate is CaWO4。
The gas-sensitive coating is WO formed by self-assembling nano sheets3The gas sensor with nanoflower has a structure as shown in FIG. 2, wherein Ni-Cr heating wire 2 crosses Al2O3A ceramic tube 1 welded on the heating electrode of the hexagonal base, and a gold electrode 3 coated on Al2O3The outer surface of the ceramic tube 1 is welded on a measuring electrode of a hexagonal base through 4 platinum wires 4, and the gas-sensitive coating 5 is coated on the gold electrode 3 and the outer surface of the ceramic tube 1. The coating 5 comprises WO formed by self-assembling nano sheets3The nano-sheet has a hexagonal crystal structure, the diameter of the nano-sheet is 300-420 nm, the thickness of the nano-sheet is 100-140 nm, the length of the nano-sheet is 170-390 nm, the width of the nano-sheet is 120-140 nm, the thickness of the nano-sheet is 30-50 nm, and the nano-sheet has high porosity and specific surface area.
WO self-assembled by nano sheets3The X-ray diffraction pattern of the nanoflower is shown in FIG. 3, and the results show that WO prepared in this example3The nanoflower has a hexagonal phase crystal structure and no other impurity peaks, indicating good crystallization conditions. Self-assembled by nano sheetsWO thus obtained3The scanning electron micrographs of the nanoflower at low magnification and at high magnification are shown in FIG. 4, from which it can be seen that the obtained product is WO in which the nanoflakes are orderly self-assembled3The nanometer flower has the diameter of 300-420 nm and the thickness of 100-140 nm, the length of the nanometer sheet is 170-390 nm, the width of 120-140 nm and the thickness of 30-50 nm, and the nanometer flower has large porosity and specific surface area.
WO synthesized by self-assembling nano sheets through scheelite concentrate3The preparation method of the nanoflower comprises the following steps:
putting the scheelite concentrate into a NaOH solution with the concentration of 17.57mol/L, leaching under the experimental conditions of a liquid-solid ratio of 1:1, a reaction temperature of 180 ℃, a stirring speed of 400rpm and a heat preservation time of 120min, filtering an obtained leaching product to obtain filtrate and leaching residues, washing the leaching residues with deionized water for 3 times to obtain washing liquid, and mixing the obtained filtrate and the obtained washing liquid to obtain a leaching solution containing tungstate ions, wherein the concentration of W in the leaching solution is 122.2 g/L;
②, taking out 5mL of the leachate obtained in the step ①, slowly adding the leachate into 12mL of HCl solution with the concentration of 3mol/L, and magnetically stirring for 2min to obtain white tungstic acid precipitate;
③, washing the white tungstic acid precipitate obtained in the second step by deionized water, centrifuging for 5 times to obtain a clean tungstic acid product, then adding 40mL of deionized water into the product, and then adding 0.5mL of H with the concentration of 30 percent2O2Magnetically stirring at 27 ℃ for 10min, adjusting the pH value of the mixed solution to 1.5 by using an HCl solution with the concentration of 3mol/L, magnetically stirring the solution at 27 ℃ for 10min, and finally carrying out hydrothermal reaction on the mixed solution at the constant temperature of 160 ℃ for 12 h;
④, washing the white precipitate obtained in the third step with deionized water for 5 times, and drying for 24 hours at the temperature of 60 ℃;
fifthly, the product obtained in the step (iv) is thermally treated for 4 hours at 400 ℃ to obtain the WO self-assembled by the nano sheets3And (4) nano flowers.
⑥ will step togetherthe obtained WO self-assembled by nano sheets3Adding the nanoflower into absolute ethyl alcohol, and performing ultrasonic dispersion to obtain viscous slurry; uniformly brushing the viscous slurry on the gold electrode 3 and Al2O3Preparing a gas-sensitive coating 5 on the outer surface of the ceramic tube 1, and coating Al of the gas-sensitive coating 5 on the outer surface of the ceramic tube2O3Placing the ceramic tube 1 in the air for natural drying for 30min, and then enabling the Ni-Cr heating wire 2 to transversely penetrate through Al2O3The ceramic tube 1, and weld its both ends to the heating electrode of the hexagonal base; connecting a platinum wire 4 with a gold electrode 3 on the outer surface of the ceramic tube 1, welding the platinum wire on a measuring electrode of a hexagonal base, placing the obtained gas-sensitive element on an aging table, aging for 24h at 300 ℃, and finally obtaining a WO gas-sensitive coating formed by self-assembling nano sheets3NO of nanoflower2A gas sensor.
WO self-assembled by nano sheets in the working temperature range of 50 ℃ to 225 DEG C3Nanoflower gas sensor to 5ppm NO2The dynamic response curve of the gas is shown in fig. 5. As can be seen from the figure, the gas sensor of the present invention is for NO2The gas has good reaction reversibility and short response/recovery time, and the resistance change of the gas is most obvious at 100 ℃. The change range of the resistance is in a descending trend as the working temperature is continuously increased.
WO self-assembled by nano sheets3Nanoflower gas sensor to 5ppm NO2The graph of the sensitivity of the gas versus operating temperature is shown in fig. 6. It can be seen from the graph that the sensitivity of the gas shows a tendency of increasing first and then decreasing with the increase of the operating temperature, and the maximum sensitivity is obtained at the operating temperature of 100 ℃, which will effectively reduce the power consumption of the gas sensor, and is one of the advantages of the present invention.
The gas sensor of the invention can measure 5ppm NO under different working temperature conditions2The response and recovery time profiles of the gas are shown in figure 7. As can be seen from the graph, the response and recovery time of the gas sensor show a gradually decreasing trend along with the increase of the operating temperature. The response time and the working temperature show obvious linear relation, and the recovery time is between 75 ℃ and 100 DEG CA large amplitude change. The gas-sensitive coating is WO formed by self-assembling nano sheets3The gas sensor of the nanoflower can measure 5ppm NO at the optimum working temperature of 100 DEG C2The response and recovery times of the gas were 118s and 338s, respectively.
FIG. 8 shows WO formed by self-assembly of nanosheets3The nanoflower gas sensitive element can be used for detecting NO with different concentrations at the working temperature of 100 DEG C2Dynamic response profile of gas. As can be seen from the figure, the gas sensor is used for different concentrations of NO in 7 consecutive reaction cycles2The gas has good response reversibility; resistance change of gas sensor with NO2The gas concentration increased and showed a tendency to increase, indicating that the gas sensitivity was dependent on NO2The concentration increases.
The gas-sensitive coating is WO formed by self-assembling nano sheets3Sensitivity of gas sensor with nanoflower at 100 deg.C and NO2The relationship between the gas concentrations is shown in fig. 9. As can be seen from the figure, the gas-sensitive coating is WO formed by self-assembling nano sheets3Gas sensor of nanoflower for 50ppb, 100ppb, 300ppb, 500ppb, 1ppm, 3ppm and 5ppm NO2The sensitivity of the gas is 1.86, 2.63, 5.11, 7.98, 13.48, 24.65 and 36.07 respectively, and the WO self-assembled by the nano-sheets is illustrated3The nanoflower gas sensor can be used for detecting low-concentration even ppb level NO2Gas, which is the greatest advantage of the present invention.
FIG. 10 shows the gas sensor of the present invention at 100 ℃ for 5ppm NO2Reproducibility curve of gas. As can be seen from the figure, the gas sensor is used for 5ppm NO in 5 consecutive reaction cycles2The gas can be quickly recovered to the initial resistance value and the variation range of the resistance value is not greatly different, which shows that the gas sensor is used for NO2The gas has good response reversibility and reproducibility.
FIG. 11 shows WO formed by self-assembly of nanosheets3The gas sensor of the nanoflower can be used for detecting 5ppm NO at the working temperature of 100 DEG C2And 1000ppm of methanol, NH3Formaldehyde and 100ppm toluene, SO2The sensitivity of the gas.As can be seen from the figure, the gas sensor of the present invention can detect NO under the same detection conditions2The selectivity to the gas is best and the selectivity to the other gases is poor.
Example 2
The gas-sensitive coating is WO formed by self-assembling nano sheets3The gas sensor with nanoflower has the structure as shown in FIG. 2.
WO synthesized by self-assembling nano sheets through scheelite concentrate3Preparation method of nanoflower and NO2The gas sensor is carried out according to the following steps:
putting the scheelite concentrate into a NaOH solution with the concentration of 15mol/L, leaching under the experimental conditions of the liquid-solid ratio of 2:1, the reaction temperature of 170 ℃, the stirring speed of 600rpm and the heat preservation time of 180min, filtering the obtained leaching product to obtain filtrate and leaching residue, washing the leaching residue with deionized water for 3 times to obtain washing liquid, and mixing the obtained filtrate and the obtained washing liquid to obtain a leaching solution containing tungstate ions, wherein the concentration of W in the leaching solution is 50 g/L;
②, taking out 5mL of the leachate obtained in the step ①, slowly adding the leachate into 10mL of HCl solution with the concentration of 3mol/L, and magnetically stirring for 4min to obtain white tungstic acid precipitate;
③, washing the white tungstic acid precipitate obtained in the second step by deionized water, centrifuging for 5 times to obtain a clean tungstic acid product, then adding 30mL of deionized water into the product, and then adding 0.2mL of H with the concentration of 30 percent2O2Magnetically stirring at 20 ℃ for 20min, adjusting the pH of the mixed solution to 1.2 by using an HCl solution with the concentration of 2mol/L, magnetically stirring the solution at 20 ℃ for 15min, and finally carrying out hydrothermal reaction on the mixed solution at the constant temperature of 100 ℃ for 4 h;
④, washing the white precipitate obtained in the third step for 6 times by using deionized water, and drying for 18 hours at 70 ℃;
fifthly, the product obtained in the step (iv) is thermally treated for 8 hours at 450 ℃, thus obtaining the WO self-assembled by nano sheets3And (4) nano flowers.
sixthly, thestep five, the obtained WO self-assembled by nano sheets3Adding the nanoflower into absolute ethyl alcohol, and performing ultrasonic dispersion to obtain viscous slurry; uniformly brushing the viscous slurry on the gold electrode 3 and Al2O3Preparing a gas-sensitive coating 5 on the outer surface of the ceramic tube 1, and coating Al of the gas-sensitive coating 5 on the outer surface of the ceramic tube2O3Placing the ceramic tube 1 in the air for natural drying for 30min, and then enabling the Ni-Cr heating wire 2 to transversely penetrate through Al2O3The ceramic tube 1, and weld its both ends to the heating electrode of the hexagonal base; connecting a platinum wire 4 with a gold electrode 3 on the outer surface of the ceramic tube 1, welding the platinum wire on a measuring electrode of a hexagonal base, placing the obtained gas-sensitive element on an aging table, aging for 24h at 300 ℃, and finally obtaining a WO gas-sensitive coating formed by self-assembling nano sheets3NO of nanoflower2A gas sensor.
Through detection, the WO prepared by the embodiment and self-assembled by the nanosheets3The nano flower gas sensitive element is used for NO under the working temperature condition of 50-225 DEG C2The gas has good response recovery performance.
Example 3
The gas-sensitive coating is WO formed by self-assembling nano sheets3The gas sensor with nanoflower has the structure as shown in FIG. 2.
WO synthesized by self-assembling nano sheets through scheelite concentrate3Preparation method of nanoflower and NO2The gas sensor is carried out according to the following steps:
putting the scheelite concentrate into a NaOH solution with the concentration of 18mol/L, leaching under the experimental conditions of a liquid-solid ratio of 3:1, a reaction temperature of 190 ℃, a stirring speed of 700rpm and a heat preservation time of 30min, filtering an obtained leaching product to obtain filtrate and leaching residue, washing the leaching residue with deionized water for 3 times to obtain washing liquid, and mixing the obtained filtrate and the obtained washing liquid to obtain a leaching solution containing tungstate ions, wherein the concentration of W in the leaching solution is 200 g/L;
②, taking out 5mL of the leachate obtained in the step ①, slowly adding the leachate into 25mL of HCl solution with the concentration of 4mol/L, and magnetically stirring for 5min to obtain white tungstic acid precipitate;
③, washing the white tungstic acid precipitate obtained in the second step by deionized water, centrifuging for 5 times to obtain a clean tungstic acid product, then adding 50mL of deionized water into the product, and then adding 1mL of H with the concentration of 30 percent2O2Magnetically stirring the mixture at 30 ℃ for 15min, adjusting the pH value of the mixed solution to 1.8 by using an HCl solution with the concentration of 4mol/L, magnetically stirring the solution at 30 ℃ for 20min, and finally carrying out hydrothermal reaction on the mixed solution at the constant temperature of 180 ℃ for 16 h;
④, washing the white precipitate obtained in the third step with deionized water for 5 times, and drying for 12 hours at the temperature of 80 ℃;
fifthly, the product obtained in the step (iv) is thermally treated for 8 hours at 500 ℃ to obtain the WO self-assembled by the nano sheets3And (4) nano flowers.
sixthly, the WO obtained in the fifth step and formed by self-assembling nano sheets3Adding the nanoflower into absolute ethyl alcohol, and performing ultrasonic dispersion to obtain viscous slurry; uniformly brushing the viscous slurry on the gold electrode 3 and Al2O3Preparing a gas-sensitive coating 5 on the outer surface of the ceramic tube 1, and coating Al of the gas-sensitive coating 5 on the outer surface of the ceramic tube2O3Placing the ceramic tube 1 in the air for natural drying for 30min, and then enabling the Ni-Cr heating wire 2 to transversely penetrate through Al2O3The ceramic tube 1, and weld its both ends to the heating electrode of the hexagonal base; connecting a platinum wire 4 with a gold electrode 3 on the outer surface of the ceramic tube 1, welding the platinum wire on a measuring electrode of a hexagonal base, placing the obtained gas-sensitive element on an aging table, aging for 24h at 300 ℃, and finally obtaining a WO gas-sensitive coating formed by self-assembling nano sheets3NO of nanoflower2A gas sensor.
Through detection, the WO prepared by the embodiment and self-assembled by the nanosheets3The nano flower gas sensitive element is used for NO under the working temperature condition of 50-225 DEG C2The gas has good response recovery performance.
Claims (10)
1. WO (WO)3Nanomaterial characterized in that said WO3The nanometer material has hexagonal phase crystal structure(ii) a Said WO3The shape of the nano material is a nanoflower consisting of nano sheets; the diameter of the nanoflower is 300-420 nm, the thickness of the nanoflower is 100-140 nm, the length of the nanosheet is 170-390 nm, the width of the nanosheet is 120-140 nm, and the thickness of the nanosheet is 30-50 nm.
2. A WO according to claim 13The preparation method of the nano material is characterized by comprising the following steps:
extracting tungsten in the white tungsten concentrate by adopting a sodium hydroxide leaching process to obtain a leaching solution, wherein the concentration of a sodium hydroxide solution is 15-18 mol/L, and the concentration of W in the leaching solution is 50-200 g/L;
②, taking out the leachate obtained in the step ①, adding the leachate into an HCl solution, and magnetically stirring for 2-5 min to obtain a white tungstic acid precipitate, wherein the concentration of the HCl solution is 2-4 mol/L, and the volume ratio of the leachate to the HCl solution is 1: 2-1: 5;
③, centrifuging, washing and drying the white tungstic acid precipitate obtained in the step ② to obtain a tungstic acid product, then adding deionized water into the tungstic acid product, and then adding H with the concentration of 30 percent2O2Magnetically stirring the mixture for 10 to 20min at the temperature of between 20 and 30 ℃, then adjusting the pH value of the mixed solution to between 1.2 and 1.8 by using an HCl solution with the concentration of between 2 and 4mol/L, magnetically stirring the solution for 10 to 20min at the temperature of between 20 and 30 ℃, and carrying out hydrothermal reaction for 4 to 16h at the constant temperature of between 100 and 180 ℃ to obtain a white precipitate; the dosage ratio of the volume of the deionized water to the mass of tungsten (W) in the tungstic acid product is 50-120 mL:1 g; tungsten (W) and H in the tungstic acid product2O2The mass ratio of (A) to (B) is 0.8-1.2: 1;
fourthly, washing, drying and heat treating the white precipitate obtained in the step ③ to obtain the WO3And (3) nano materials.
3. The method according to claim 2, characterized in that the grade of the scheelite concentrate is 62.36%.
4. the method according to claim 2, wherein the step ① of extracting tungsten in the scheelite concentrate by using a sodium hydroxide leaching process comprises the specific steps of putting the scheelite concentrate into a NaOH solution, leaching under the experimental conditions of controlling the liquid-solid ratio of 1: 1-3: 1, the reaction temperature of 170-190 ℃, the stirring speed of 400-700 rpm and the heat preservation time of 30-180 min, and filtering to obtain filtrate and leaching residues, wherein the filtrate is leachate.
5. the method according to claim 2, wherein the drying temperature in step ③ is 60-80 ℃ and the drying time is 12-24 hours.
6. the method according to claim 2, wherein the product obtained in the step (iv) is subjected to heat treatment at 400-500 ℃ for 4-8 h.
7. The method according to claim 4, wherein the leached residue is washed with deionized water to obtain a washing solution, and the washing solution is mixed with the filtrate to obtain the leached solution.
8. Gas-sensitive coating, characterized in that the material of the gas-sensitive coating comprises WO according to claim 13And (3) nano materials.
9. A gas sensor, wherein the gas sensor coating is the gas sensor coating according to claim 8, and the gas sensor further comprises Al2O3Ceramic tube, gold electrode, platinum wire, Ni-Cr heating wire, gold electrode and Al2O3A ceramic tube; the gas-sensitive coating is attached to Al2O3The outer surface of the ceramic tube.
10. NO (nitric oxide)2The gas sensor, wherein the gas sensitive coating of the gas sensor of the sensor is the gas sensitive coating of claim 8 or the gas sensor of the sensor is the gas sensor of claim 9.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105948129A (en) * | 2016-06-12 | 2016-09-21 | 南昌航空大学 | Controllable synthesis method for different nanocrystalline types of WO3 and application of method to wastewater |
| CN106430313A (en) * | 2016-09-26 | 2017-02-22 | 安阳师范学院 | Hollow flower-clump-shaped hierarchically-structured gas-sensitive WO3 material, synthesizing method and application |
| CN106807359A (en) * | 2017-03-01 | 2017-06-09 | 南京信息工程大学 | A kind of simple method for preparing of the hexapetalous flower shape tungsten trioxide photocatalyst containing heterojunction structure |
| CN107055619A (en) * | 2017-03-27 | 2017-08-18 | 浙江大学 | A kind of multilevel hierarchy WO3And preparation method thereof |
-
2019
- 2019-07-18 CN CN201910649152.7A patent/CN110255621B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105948129A (en) * | 2016-06-12 | 2016-09-21 | 南昌航空大学 | Controllable synthesis method for different nanocrystalline types of WO3 and application of method to wastewater |
| CN106430313A (en) * | 2016-09-26 | 2017-02-22 | 安阳师范学院 | Hollow flower-clump-shaped hierarchically-structured gas-sensitive WO3 material, synthesizing method and application |
| CN106807359A (en) * | 2017-03-01 | 2017-06-09 | 南京信息工程大学 | A kind of simple method for preparing of the hexapetalous flower shape tungsten trioxide photocatalyst containing heterojunction structure |
| CN107055619A (en) * | 2017-03-27 | 2017-08-18 | 浙江大学 | A kind of multilevel hierarchy WO3And preparation method thereof |
Non-Patent Citations (3)
| Title |
|---|
| Effects of different petal thickness on gas sensing properties of flower-like WO3·H2O hierarchical architectures;Wen Zeng等;《Applied Surface Science》;20150417;73–78 * |
| Hydrothermal synthesis of WO3·H2O with different nanostructures from 0D to 3D and their gas sensing properties;Yangchun Yu等;《Physica E》;20151222;127–132 * |
| Temperature and acidity effects on WO3 nanostructures and gassensing;Huili Zhang等;《Materials Research Bulletin》;20140612;260–267 * |
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