Fluoroborate modified metal oxide gas-sensitive material and preparation method and application thereof

Abstract

The present invention discloses a fluoborate-modified metal oxide gas-sensitive material, its preparation method and application. The preparation method includes the following steps: mixing a metal oxide nanomaterial with a fluoborate solution, dispersing it evenly, reacting at a set temperature for a set time, enabling fluoride ions generated by the hydrolysis of fluoborate ions to diffuse into the lattice of the metal oxide to achieve doping of fluoride ions; and the fluoborate hydrolyzes on the surface of the metal oxide to graft BF3 groups on the material surface to obtain the gas-sensitive material. The doping of fluoride ions generates defects on the material surface and narrows the band gap, which is beneficial to the adsorption and reaction of gas molecules on the material surface. The BF3 groups on the surface can capture water molecules by forming hydrogen bonds, thereby improving the humidity stability performance of the material. It enables efficient and sensitive detection of target gases in a high-humidity environment and has excellent practical application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensitive materials, and specifically relates to a fluoroborate modified metal oxide gas sensitive material and a preparation method and application thereof. The gas sensitive material is mainly used for detecting gas concentration in a high humidity environment. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Waste gas emitted into the atmosphere by industrial production and automobile exhaust is one of the main sources of air pollution, mainly including nitrogen oxides, sulfur oxides, carbon monoxide, carbon dioxide and hydrocarbons. These gases can not only cause environmental problems such as acid rain, photochemical smog, and greenhouse effect, but also pose a serious threat to human health.

[0004] In order to protect the ecological environment and human health, people have adopted a variety of methods to detect and monitor these toxic and harmful gases in real time. Among them, resistive semiconductor gas sensors are widely used due to their small size, low cost, easy integration and automation. At present, the sensitive materials of resistive semiconductor gas sensors are usually metal oxide materials. Such materials have good gas-sensing properties and are easy to synthesize, which is conducive to practical applications. However, the gas-sensing properties of such gas-sensitive semiconductor materials are greatly affected in high humidity environments. Water molecules in the gas environment will react with oxygen ions on the surface of the material to generate hydroxyl groups with low reaction activity and adsorb on the surface of the material, which is not conducive to the adsorption and reaction of the gas to be measured. In addition, in a high humidity environment, water vapor may also cover the surface of the material, affecting the contact between the gas and the surface of the gas-sensitive material, which is not conducive to the gas-sensing process. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a fluoroborate-modified metal oxide gas-sensitive material and a preparation method and application thereof.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a fluoroborate-modified metal oxide gas-sensitive material, comprising the following steps:

[0008] The metal oxide nanomaterial is mixed with the fluoroborate solution, dispersed evenly, and reacted at a set temperature for a set time, so that the fluorine ions generated by the hydrolysis of the fluoroborate ions diffuse into the lattice of the metal oxide to achieve fluorine ion doping; and the fluoroborate ions are hydrolyzed on the surface of the metal oxide, and BF is grafted on the surface of the material. 3 Group to obtain gas-sensitive material.

[0009] In a second aspect, the present invention provides a fluoroborate-modified metal oxide gas-sensitive material, which is prepared by the preparation method, and the surface of the metal oxide nanomaterial is grafted with BF 3 groups, and fluorine ions are doped in the crystal lattice.

[0010] In a third aspect, the present invention provides an application of the fluoroborate-modified metal oxide gas-sensitive material in gas detection, especially in gas detection under a high humidity environment.

[0011] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0012] (1) The present invention provides a fluoroborate-modified metal oxide gas-sensitive material, wherein the modification of fluoroborate does not change the physical phase and morphology of the original metal oxide, and can maintain the advantages of the original metal oxide nanomaterial in terms of morphology, structure, specific surface area, etc. At the same time, part of the fluorine ions generated by the hydrolysis of fluoroborate ions diffuse and dope into the lattice of the metal oxide, forming fluorine ion doping, generating defects on the surface of the material, and narrowing the bandgap, which is beneficial to the adsorption and reaction of gas molecules on the surface of the material; in addition, part of the fluoroborate ions hydrolyzes on the surface of the metal oxide, and BF is grafted on the surface of the material. 3 Group, surface BF 3 The group can capture water molecules by forming hydrogen bonds, thereby improving the humidity stability of the material, enabling it to detect target gases efficiently and sensitively in high humidity environments, and has excellent practical application value.

[0013] (2) The fluoroborate-modified metal oxide gas-sensitive material of the present invention solves a series of defects existing in the current metal oxide-based gas sensors, such as low sensitivity, poor selectivity, poor humidity stability, etc. The fluoroborate-modified metal oxide gas-sensitive material can detect the target gas efficiently and sensitively in a high humidity environment, and has strong practical value.

[0014] (3) The preparation method of the fluoroborate-modified metal oxide gas-sensitive material of the present invention is to modify the metal oxide by immersing it in a fluoroborate solution, and the fluorine ion doping concentration and the grafted BF in the product can be conveniently controlled by changing the concentration of the fluoroborate solution and the immersion time. 3 The group concentration has the advantages of being simple and easy to operate, the required equipment is simple and easy to operate, the process parameters are convenient to adjust, less raw materials are required, and the cost is low, and it has good practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 is a SEM image of pure zinc oxide nanobeams prepared in Comparative Example 1 of the present invention;

[0017] Figure 2 is a SEM image of the fluoroborate-modified zinc oxide nanobeams prepared in Example 1;

[0018] Figure 3 The XRD spectra of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1, Example 2 and Comparative Example 1, wherein (a) is the XRD spectrum in the 10-90° region, and (b) is an enlarged view of the strongest peak region;

[0019] Figure 4 This is the XPS spectrum of the fluoroborate-modified zinc oxide nanobeams prepared in Example 1, wherein (a) is a fine spectrum in the B1s region, (b) is a fine spectrum in the F1s region, and (c) is a fine spectrum in the O1s region;

[0020] Figure 5 FT-IR spectra of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Example 2 and Comparative Example 1.

[0021] Figure 6 The response values ​​of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1, Example 2 and Comparative Example 1 to 5 ppm nitrogen dioxide at different temperatures;

[0022] Figure 7 The response recovery curves of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1, Example 2 and Comparative Example 1 to 5 ppm nitrogen dioxide at 160°C.

[0023] Figure 8 The dynamic response recovery curves of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1 to different concentrations of nitrogen dioxide at 160°C;

[0024] Fig. 9 It is a bar graph of the response values ​​of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1 and Comparative Example 1 to different gases at 160° C.;

[0025] Fig.10 The relative change curves of the response values ​​of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Example 1 and Comparative Example 1 to 5 ppm nitrogen dioxide at 160° C. and different humidity conditions;

[0026] Fig.11 This is a SEM image of pure tungsten trioxide nanorods prepared in Comparative Example 2;

[0027] Fig.12 is a SEM image of the fluoroborate-modified tungsten trioxide nanorods prepared in Example 3;

[0028] Fig.13 The XRD spectra of the fluoroborate-modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3, Example 4 and Comparative Example 2, wherein (a) is the XRD spectrum in the 10-90° region, and (b) is an enlarged view of the strongest peak region;

[0029] Fig.14 The response value changes of the fluoroborate modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3, Example 4 and Comparative Example 2 to 10 ppm hydrogen sulfide at different temperatures;

[0030] Fig.15 It is the response recovery curve of the fluoroborate modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3 and Comparative Example 2 to 10 ppm hydrogen sulfide at 160°C.

[0031] Fig.16 is a bar graph of the response values ​​of the fluoroborate modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3 to different gases at 160°C;

[0032] Fig.17 It is a relative change curve of the response value of the samples prepared in Example 3, Example 4 and Comparative Example 2 to 10 ppm hydrogen sulfide at 160° C. and different humidity. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] As mentioned above, the metal oxide semiconductor materials currently used in gas sensors usually have disadvantages such as low sensitivity, poor selectivity, poor humidity stability, etc. In view of this, the present invention proposes a fluoroborate-modified metal oxide gas-sensitive material for gas detection under high humidity.

[0035] In a first aspect, the present invention provides a method for preparing a fluoroborate-modified metal oxide gas-sensitive material, comprising the following steps:

[0036] The metal oxide nanomaterial is mixed with the fluoroborate solution, dispersed evenly, and reacted at a set temperature for a set time, so that the fluorine ions generated by the hydrolysis of the fluoroborate ions diffuse into the lattice of the metal oxide to achieve fluorine ion doping; and the fluoroborate ions are hydrolyzed on the surface of the metal oxide, and BF is grafted on the surface of the material.3 Group to obtain gas-sensitive material.

[0037] In some embodiments, the metal oxide is any one or more of zinc oxide, tungsten trioxide, tin dioxide, nickel oxide, cobalt trioxide, copper oxide, cerium dioxide, iron oxide, titanium oxide, molybdenum trioxide, and indium oxide.

[0038] In some embodiments, the fluoroborate is selected from one or more of sodium fluoroborate, potassium fluoroborate or ammonium fluoroborate;

[0039] Preferably, the solvent of the fluoroborate solution is selected from one or more of deionized water, anhydrous ethanol, anhydrous methanol or N,N-dimethylformamide. The solvent should have high solubility for fluoroborate and be able to dissociate fluoroborate.

[0040] Further preferably, the solvent of the fluoroborate solution is deionized water.

[0041] In some embodiments, the concentration of the fluoroborate solution is 0.01-5 mol / L, preferably 0.05-1 mol / L.

[0042] Preferably, the amount of the metal oxide nanomaterial added to each milliliter of the fluoroborate solution is 1-10 mg, preferably 2.5-5 mg.

[0043] In some embodiments, during the mixing of the metal oxide nanomaterial and the fluoroborate solution, the ultrasonic treatment time is 5-30 min, preferably 5-15 min.

[0044] Ultrasonic treatment facilitates uniform mixing of metal oxide nanomaterials and fluoroborate solution, and at the same time helps fluoride ions produced by hydrolysis of fluoroborate ions diffuse into the lattice of the metal oxide, forming fluoride ion doping, generating defects on the material surface, and narrowing the bandgap, which is beneficial to the adsorption and reaction of gas molecules on the material surface.

[0045] In some embodiments, the temperature for reacting the metal oxide nanomaterial with the fluoroborate is 10-80° C. and the time is 1-10 h; preferably, the reaction temperature is 25° C. and the reaction time is 4-6 h.

[0046] In a second aspect, the present invention provides a fluoroborate-modified metal oxide gas-sensitive material, which is prepared by the preparation method, and the surface of the metal oxide nanomaterial is grafted with BF 3 groups, and fluorine ions are doped in the crystal lattice.

[0047] In a third aspect, the present invention provides an application of the fluoroborate-modified metal oxide gas-sensitive material in gas detection, especially in gas detection under a high humidity environment.

[0048] In some embodiments, the gas is nitrogen dioxide, hydrogen sulfide, carbon monoxide, or sulfur dioxide.

[0049] In some embodiments, the relative humidity of the detection environment is RH10-RH90.

[0050] The present invention will be further described below in conjunction with specific implementations and accompanying drawings.

[0051] Embodiment 1

[0052] A method for preparing fluoroborate-modified zinc oxide nanobeams comprises the following steps:

[0053] (1) Add 0.66 g of zinc acetate dihydrate and 2.4 g of sodium hydroxide to 9 mL of deionized water and stir until dissolved. Then add 21 mL of glycerol and stir to form a uniform solution.

[0054] (2) The above solution was transferred to a 40 mL reactor, hydrothermaled at 120° C. for 24 h, and zinc oxide nanobeams were obtained after centrifugation, washing, and drying;

[0055] (3) 0.22 g of sodium fluoroborate was added to 20 mL of deionized water to prepare a 0.1 mol / L solution, 0.05 g of the above zinc oxide nanobeams was added to the solution, ultrasonically dispersed for 10 min, stirred at 25 ° C for 4 h, and then the obtained sample was centrifuged, washed, and dried to obtain the fluoroborate-modified zinc oxide nanobeam material.

[0056] Embodiment 2

[0057] A method for preparing a fluoroborate-modified zinc oxide material nanobeam, the specific steps are the same as those of Example 1, except that: the masses of sodium fluoroborate added in step (3) are 0.11 g, 1.1 g, and 2.2 g, respectively, that is, the concentrations of the prepared solutions are 0.05 mol / L, 0.5 mol / L, and 1 mol / L.

[0058] Embodiment 3

[0059] A method for preparing fluoroborate-modified tungsten trioxide nanorods comprises the following steps:

[0060] (1) Add 1.32 g of sodium tungstate dihydrate to 40 mL of deionized water, stir until dissolved, add 5% dilute sulfuric acid dropwise to adjust the pH to 1.6, then add 4.0 g of sodium sulfate and 1.0 g of oxalic acid dihydrate, and stir to form a clear solution;

[0061] (2) The above solution was transferred to a 100 mL reactor, hydrothermaled at 180°C for 12 h, and tungsten trioxide nanorods were obtained after centrifugation, washing, and drying;

[0062] (3) 0.11 g of sodium fluoroborate was added to 20 mL of deionized water to prepare a 0.05 mol / L solution, 0.05 g of the above-mentioned tungsten trioxide nanorods was added to the solution, ultrasonically dispersed for 10 min, stirred at 25 ° C for 4 h, and then the obtained sample was centrifuged, washed, and dried to obtain the fluoroborate modified tungsten trioxide nanorod material.

[0063] Embodiment 4

[0064] A method for preparing fluoroborate-modified tungsten trioxide material nanorods, the specific steps are the same as those of specific embodiment 3, except that: the masses of sodium fluoroborate added in step (3) are 0.22g, 1.1g, and 2.2g, respectively, that is, the concentrations of the prepared solutions are 0.1mol / L, 0.5mol / L, and 1mol / L.

[0065] Embodiment 5

[0066] A method for preparing fluoroborate-modified tin dioxide nanospheres comprises the following steps:

[0067] (1) Add 0.42 g of tin tetrachloride pentahydrate and 0.5 g of polyvinyl pyrrolidone (PVP, K30) to 60 mL of methanol and stir until dissolved to form a uniform solution;

[0068] (2) The above solution was transferred to a 100 mL reactor, hydrothermaled at 180° C. for 3 h, and then centrifuged, washed, and dried to obtain porous tin dioxide nanospheres;

[0069] (3) 0.11 g of sodium fluoroborate was added to 20 mL of deionized water to prepare a 0.05 mol / L solution, 0.05 g of the above-mentioned tin dioxide nanospheres was added to the solution, ultrasonically dispersed for 10 min, stirred at 25 ° C for 4 h, and then the obtained sample was centrifuged, washed, and dried to obtain the fluoroborate-modified tin dioxide nanosphere material.

[0070] Embodiment 6

[0071] A method for preparing a fluoroborate-modified tin dioxide nanosphere material, the specific steps are the same as those of specific embodiment 5, except that: the masses of sodium fluoroborate added in step (3) are 0.22g, 1.1g, and 2.2g, respectively, that is, the concentrations of the prepared solutions are 0.1mol / L, 0.5mol / L, and 1mol / L.

[0072] Embodiment 7

[0073] A method for preparing fluoroborate-modified zinc oxide nanobeams comprises the following steps:

[0074] (1) and (2) are the same as in Example 1;

[0075] (3) 0.13 g of sodium fluoroborate was added to 20 mL of deionized water to prepare a 0.05 mol / L solution, 0.1 g of the above zinc oxide nanobeams was added to the solution, ultrasonically dispersed for 10 min, stirred at 25 ° C for 6 h, and then the obtained sample was centrifuged, washed, and dried to obtain the fluoroborate-modified zinc oxide nanobeam material.

[0076] Embodiment 8

[0077] A method for preparing a fluoroborate-modified tungsten trioxide nanorod material comprises the following steps:

[0078] (1) and (2) are the same as those in Example 3;

[0079] (3) 0.10 g of ammonium fluoroborate was added to 20 mL of deionized water to prepare a 0.05 mol / L solution, 0.1 g of the above-mentioned tungsten trioxide nanorods was added to the solution, ultrasonically dispersed for 10 min, stirred at 25 ° C for 10 h, and then the obtained sample was centrifuged, washed, and dried to obtain the fluoroborate modified tungsten trioxide nanorod material.

[0080] Comparative Example 1

[0081] A method for preparing pure zinc oxide nanobeams, the specific steps are the same as those of the specific embodiment 1, the difference being that sodium fluoroborate is not added in step (3), that is, the concentration of the prepared solution is 0 mol / L.

[0082] Comparative Example 2

[0083] A method for preparing pure tungsten trioxide nanorods, the specific steps are the same as those of the specific embodiment 1, the difference is that sodium fluoroborate is not added in step (3), that is, the concentration of the prepared solution is 0 mol / L.

[0084] Performance Testing

[0085] Figure 1 This is a SEM image of the pure zinc oxide nanobeam prepared in Comparative Example 1. It can be seen from the figure that the prepared pure zinc oxide presents a bundle structure composed of multiple nanorods. The length of the nanorods is about 1.5 μm and the diameter is about 150 nm.

[0086] Figure 2 This is an SEM image of the fluoroborate-modified zinc oxide nanobeams prepared in Example 1. It can be seen from the figure that the morphology of the sample after fluoroborate modification is still a nanobeam structure, which is basically the same as before modification, proving that the modification of fluoroborate will not change the morphological structure of zinc oxide.

[0087] Figure 3 3 and 4. It is the XRD spectrum of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Examples 1 and 2 and Comparative Example 1. It can be seen from the figure that the crystal structure of the zinc oxide nanobeams before and after fluoroborate modification has not changed significantly, while the strongest peak of the sample after doping is obviously shifted to the right, proving that substitutional doping of fluoride ions has occurred.

[0088] Figure 4 This is the XPS spectrum of the fluoroborate-modified zinc oxide nanobeams prepared in Example 1. In the B1s spectrum of the fluoroborate-modified zinc oxide, it can be clearly seen that there is a peak at 193.3 eV, which is consistent with the BF 3 The F1s spectrum of fluoroborate-modified zinc oxide can be divided into two peaks. The peak at 685.6 eV can match the F ions, that is, the F ions are doped into the lattice of zinc oxide. The peak at 687.5 eV has a smaller intensity and can match the BF adsorbed and grafted on the surface of the metal oxide. 3 The O1s spectrum of the fluoroborate-modified zinc oxide nanobeams can be divided into three peaks. The peaks at 530.2eV and 531.6eV match the lattice oxygen and oxygen vacancies in zinc oxide, respectively. The formation of oxygen vacancies is conducive to the adsorption and dissociation of nitrogen dioxide molecules on the surface of the material, thereby improving the gas-sensing properties of the material. In addition, there is a peak with a smaller intensity at 533.2eV, which can match the oxygen element in the OB bond, further proving that the fluoroborate ions hydrolyze on the surface of the material to produce BF 3 Grafting of groups.

[0089] Figure 5 The FT-IR spectra of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Example 2 and Comparative Example 1 show that after being treated with sodium fluoroborate solution, the peak of the surface adsorbed hydroxyl groups is red-shifted, and the intensity and width increase, proving that hydrogen bonds are generated on the surface of the material, indicating that the surface grafted BF 3 The group can capture water molecules by forming hydrogen bonds, improving the material's moisture resistance. -1 A new absorption peak appeared at , which can correspond to OB, further proving that BF 3 Grafting of groups.

[0090] Figure 6The response values ​​of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Examples 1, 2 and Comparative Example 1 to 5ppm nitrogen dioxide at different temperatures. It can be seen from the figure that the optimal working temperature of pure zinc oxide and the zinc oxide material treated with 0.05 and 0.1mol / L sodium fluoroborate solutions is 160°C, while the optimal working temperature of the zinc oxide material treated with 0.5 and 1mol / L sodium fluoroborate solutions is increased to 200°C. In particular, the zinc oxide nanobeams treated with 0.1mol / L sodium fluoroborate solution have the highest sensitivity, and their response value to 5ppm nitrogen dioxide at 160°C reaches 38.33.

[0091] Figure 7 The response recovery curves of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Examples 1 and 2 and Comparative Example 1 to 5 ppm nitrogen dioxide at 160°C. It can be seen from the figure that with the increase of the concentration of the fluoroborate solution, the response time of zinc oxide to nitrogen dioxide is significantly shortened, while the recovery time does not change much.

[0092] Figure 8 This is the dynamic response recovery curve of the fluoroborate-modified zinc oxide nanobeams prepared in Example 1 to different concentrations of nitrogen dioxide at 160°C. It can be seen from the figure that the response recovery time of the material to different concentrations of nitrogen dioxide is basically the same, and the response value increases continuously with the increase of gas concentration. The minimum detection limit of the material for nitrogen dioxide gas is 0.5ppm.

[0093] Fig. 9 It is a bar graph of the response values ​​of the fluoroborate-modified zinc oxide nanobeams and pure zinc oxide nanobeams prepared in Example 1 and Comparative Example 1 to different gases at 160°C. It can be seen from the figure that compared with pure zinc oxide (the bar graph at the bottom of each row), the fluoroborate-modified zinc oxide (the bar graph at the top of each row) shows a high response to nitrogen dioxide while having relatively low response values ​​to other gases, and therefore has better selectivity.

[0094] Fig.10 The figure shows the relative changes in the response values ​​of the fluoroborate-modified zinc oxide nanobeams and the pure zinc oxide nanobeams prepared in Examples 1, 2 and Comparative Example 1 to 5 ppm nitrogen dioxide at 160°C and different humidities. It can be seen from the figure that after being treated with the fluoroborate solution, the humidity stability of the zinc oxide nanobeams is significantly improved, and with the increase of the concentration of the fluoroborate solution, its moisture resistance is continuously improved.

[0095] Fig.11 This is a SEM image of pure tungsten trioxide nanorods prepared in Comparative Example 2. It can be seen from the figure that the prepared tungsten trioxide is in the shape of nanorods with a diameter of about 200 nm and a length of 1-4 μm.

[0096] Fig.12 This is a SEM image of the fluoroborate-modified tungsten trioxide nanorods prepared in Example 3. It can be seen from the figure that the tungsten trioxide after fluoroborate treatment is still a rod-shaped structure, indicating that the fluoroborate treatment has no effect on the material morphology.

[0097] Fig.13 It is the XRD spectrum of the fluoroborate-modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3, 4 and Comparative Example 2. It can be seen from the figure that the XRD spectra of all samples are almost the same, so the fluoroborate treatment will not change the crystal structure of tungsten trioxide, but the strongest peak occurrence rate of the sample after fluoroborate treatment shifts to the right, indicating that fluoride ions are doped into the crystal lattice of tungsten trioxide.

[0098] Fig.14 The response values ​​of the fluoroborate-modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Examples 3, 4 and Comparative Example 2 to 10ppm hydrogen sulfide at different temperatures. It can be seen from the figure that the optimal working temperature of all samples is 160°C. In particular, the tungsten trioxide nanorods treated with 0.05mol / L sodium fluoroborate solution have the highest sensitivity, and its response value reaches 737.96.

[0099] Fig.15 It is the response recovery curve of the fluoroborate-modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3 and Comparative Example 2 to 10ppm hydrogen sulfide at 160°C. It can be seen from the figure that the response and recovery time of the tungsten trioxide nanorods before and after the fluoroborate modification treatment have not changed significantly, proving that the fluoroborate modification treatment has little effect on the response recovery speed of the tungsten trioxide nanorods.

[0100] Fig.16 It is a bar graph of the response values ​​of the fluoroborate-modified tungsten trioxide nanorods and pure tungsten trioxide nanorods prepared in Example 3 to different gases at 160°C. It can be seen from the figure that pure tungsten trioxide has a high response to nitrogen dioxide and ammonia in addition to hydrogen sulfide. After being modified with fluoroborate, the response of tungsten trioxide nanorods to hydrogen sulfide is greatly improved, while the response to other gases is slightly reduced, reflecting good selectivity.

[0101] Fig.17 The graph is a relative change curve of the response value of the samples prepared in Example 3, Example 4 and Comparative Example 2 to 10 ppm hydrogen sulfide at 160°C and different humidity. It can be seen from the graph that the response value of pure tungsten trioxide in a high humidity environment decreases significantly, and after being treated with a fluoroborate solution, the humidity stability of the material is significantly improved.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a fluoroborate-modified metal oxide gas-sensitive material, characterized in that: The steps include: The metal oxide nanomaterial is mixed with a fluoroborate solution, dispersed evenly, and reacted at a set temperature for a set time, so that the fluoride ions produced by the hydrolysis of fluoroborate ions diffuse into the crystal lattice of the metal oxide to achieve fluoride ion doping; and the fluoroborate ions are hydrolyzed on the surface of the metal oxide, and BF3 groups are grafted on the surface of the material to obtain a gas-sensitive material.

2. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 1, characterized in that: The metal oxide is any one or more of zinc oxide, tungsten trioxide, tin dioxide, nickel oxide, cobalt tetraoxide, copper oxide, cerium dioxide, iron oxide, titanium oxide, molybdenum trioxide, and indium oxide.

3. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 1, characterized in that: The fluoroborate is selected from one or more of sodium fluoroborate, potassium fluoroborate or ammonium fluoroborate.

4. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 3, characterized in that: The solvent of the fluoroborate solution is selected from one or more of deionized water, anhydrous ethanol, anhydrous methanol or N,N-dimethylformamide.

5. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 1, characterized in that: The concentration of the fluoroborate solution is 0.01-5 mol / L.

6. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 5, characterized in that: The concentration of the fluoroborate solution is 0.05-1 mol / L.

7. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 5, characterized in that: The amount of the metal oxide nanomaterial added to each milliliter of the fluoroborate solution is 1-10 mg.

8. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 7, characterized in that: The amount of the metal oxide nanomaterial added to each milliliter of the fluoroborate solution is 2.5-5 mg.

9. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 1, characterized in that: During the mixing process of the metal oxide nanomaterial and the fluoroborate solution, the ultrasonic treatment time is 5-30 minutes.

10. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 9, characterized in that: During the mixing process of the metal oxide nanomaterial and the fluoroborate solution, the ultrasonic treatment time is 5-15 minutes.

11. The method for preparing a fluoroborate-modified metal oxide gas-sensitive material according to claim 1, characterized in that: The temperature for the reaction of the metal oxide nanomaterial and the fluoroborate is 10-80° C. and the time is 1-10 hours.

12. A fluoroborate modified metal oxide gas-sensitive material, characterized in that: The metal oxide nanomaterial is prepared by the preparation method described in any one of claims 1 to 11, and the surface of the metal oxide nanomaterial is grafted with BF3 groups, and the lattice is doped with fluorine ions.

13. Use of the fluoroborate-modified metal oxide gas-sensitive material according to claim 12 in gas detection.

14. Use of the fluoroborate-modified metal oxide gas-sensitive material according to claim 12 in gas detection in a high humidity environment.

15. The use according to claim 13 or 14, characterized in that: The gas is nitrogen dioxide, hydrogen sulfide, carbon monoxide or sulfur dioxide.

16. The use according to claim 15, characterized in that: The relative humidity of the testing environment is RH10-RH90.

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