Boron alkene MOF two-dimensional nanosheet, preparation method thereof, gas sensor and application of boron alkene MOF two-dimensional nanosheet

Abstract

The invention relates to the technical field of gas sensing, in particular to a boron-alkene-coated MOF two-dimensional nanosheet and a preparation method thereof, a gas sensor and application, and the preparation method comprises the following steps: mixing a boron-containing multi-element layered substance, an organic ligand and an acid solution to obtain a mixed solution; and carrying out solvothermal reaction treatment on the mixed solution to obtain the boron alkene-coated MOF two-dimensional nanosheet. Under the combined action of an organic ligand and an acid solution, metal in the boron-containing multi-element layered substance is used as a metal source, and conversion from the boron-containing multi-element layered substance to a two-dimensional boron alkene (at) MOF heterostructure is achieved. The preparation process is simple, the cost is greatly reduced, the preparation process is efficient, and utilization and conversion of elements in the boron-containing multi-element layered substance can be achieved to the maximum extent. Besides, the boron alkene (at) MOF two-dimensional nanosheets prepared by the preparation method support each other to construct a reasonable heterostructure, so that the basic resistance of the composite material is reduced, and the composite material shows excellent NO2 gas sensing performance at room temperature.

Description

Technical Field

[0001] The present invention relates to the field of gas sensing technology, and in particular to a borophene@MOF two-dimensional nanosheet and a preparation method thereof, a gas sensor and applications. Background Art

[0002] Compared with bulk materials, the electrons in two-dimensional materials are confined in a two-dimensional structure. This unique structural feature gives them various unconventional physical and chemical properties. For example, borophene has superior properties such as mechanical flexibility, light transmittance, ultra-high thermal conductivity, one-dimensional nearly free electron state, metallic Dirac fermions, and superconductivity. It has been shining in many research fields, such as electronics / optoelectronics, catalysis, energy storage, and sensing. At present, the preparation strategies of borophene can be mainly divided into top-down and bottom-up. The top-down strategy has been favored by researchers due to its large-scale preparation and low requirements for experimental conditions, and has become the mainstream strategy for the preparation of borophene. However, it is limited by its multi-step preparation process, lengthy experimental route, waste liquid generated by selective etching of precursors during the experimental process, and the loss of metal elements in the raw materials, which greatly increases the time and money cost of preparation.

[0003] Metal-organic framework (MOF) materials are a new type of porous materials that self-assemble with metal ions and metal clusters as nodes and organic ligands. Thanks to its naturally large specific surface area, tunable pore structure, diverse metal components and modifiable end groups, it is considered an ideal gas sensing material. However, since the link between organic ligands and metal ions often leads to the ultra-high resistance of MOF itself, it greatly increases the difficulty of monitoring the resistance change when it is exposed to the target gas, limiting the response and transmission of the signal.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a borophene@MOF two-dimensional nanosheet and a preparation method, a gas sensor and application thereof, aiming to solve the problems of complex process and high cost in the existing construction of MOF / two-dimensional material composite materials.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing borophene@MOF two-dimensional nanosheets, comprising the steps of:

[0008] Mixing the boron-containing multi-layered material, the organic ligand and the acid solution to obtain a mixed solution;

[0009] The mixed solution is subjected to a solvothermal reaction treatment to obtain borophene@MOF two-dimensional nanosheets.

[0010] The method for preparing borophene@MOF two-dimensional nanosheets, wherein the boron-containing multi-layered material is selected from one or more of AlB2, MgB2, FeAlB, MoAlB, and WAlB.

[0011] The method for preparing borophene@MOF two-dimensional nanosheets, wherein the organic ligand is selected from one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, imidazole, trimesic acid, 2,5-dihydroxyterephthalic acid, terephthalic acid, oxalic acid, and phthalic acid.

[0012] In the method for preparing borophene@MOF two-dimensional nanosheets, the solute in the acid solution is selected from one or more of formic acid, hydrochloric acid, acetic acid, and sulfuric acid.

[0013] The method for preparing the borophene@MOF two-dimensional nanosheets, wherein the mass ratio of the boron-containing multi-layered material to the organic ligand is 1:(1-8).

[0014] The method for preparing borophene@MOF two-dimensional nanosheets, wherein the volume ratio of the solute in the acid solution to the solvent in the acid solution is (5-10):1.

[0015] The method for preparing borophene@MOF two-dimensional nanosheets, wherein the temperature of the solvent thermal reaction treatment is 150°C-200°C, and the time of the solvent thermal reaction treatment is 6h-24h.

[0016] A borophene@MOF two-dimensional nanosheet is prepared by using a preparation method of a borophene@MOF two-dimensional nanosheet.

[0017] A gas sensor comprises a ceramic sheet printed with interdigital electrodes and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is made of the borophene@MOF two-dimensional nanosheet.

[0018] The invention discloses an application of a gas sensor in a device for detecting nitrogen dioxide.

[0019] Beneficial effects: The present invention provides a borophene@MOF two-dimensional nanosheet and a preparation method thereof, a gas sensor and application, comprising the steps of: mixing a boron-containing multi-layered material, an organic ligand and an acid solution to obtain a mixed solution; subjecting the mixed solution to a solvent thermal reaction treatment to obtain a borophene@MOF two-dimensional nanosheet. The present invention realizes the transformation from a boron-containing multi-layered material directly to a two-dimensional borophene@MOF heterostructure by using the metal in the boron-containing multi-layered material as a metal source through the combined action of an organic ligand and an acid solution. The preparation process is simple, greatly reducing the cost, and the preparation process is efficient, and can maximize the utilization and conversion of elements in the boron-containing multi-layered material. In addition, the borophene@MOF two-dimensional nanosheets prepared by the preparation method support each other to construct a reasonable heterostructure, reduce the basic resistance of the composite material, and exhibit excellent NO2 gas sensing performance at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the process flow of a method for preparing borophene@MOF two-dimensional nanosheets according to the present invention;

[0021] Figure 2 This is the XRD pattern of borophene@Al-PMOF prepared in Example 1;

[0022] Figure 3 This is the XRD pattern of the borophene@Al-PMOF prepared in Example 1 after etching to remove the MOF;

[0023] Figure 4 The SEM and TEM images of AlB2 in Example 1, the products when the reaction was carried out for 0.5h, 3h, and 12h, and the borophene@Al-PMOF obtained after the reaction for 12h;

[0024] Figure 5 This is the XRD pattern of borophene@MIL-53 prepared in Example 2;

[0025] Figure 6 This is the XRD pattern of borophene@Mg-MOF-74 prepared in Example 3;

[0026] Figure 7 This is a data diagram of the room temperature sensing performance of the gas sensor device of Example 4 for 10 ppm NO2 at room temperature;

[0027] Figure 8 This is a graph of test data on the selectivity of the gas sensor device of Example 4 to interference gas. DETAILED DESCRIPTION

[0028] The present invention provides a borophene@MOF two-dimensional nanosheet and a preparation method thereof, a gas sensor and application. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0030] The traditional strategy for constructing MOF / two-dimensional material composites often requires first etching to prepare the two-dimensional material, and then self-assembling it with the MOF, which is time- and money-intensive.

[0031] Based on this, Figure 1 As shown, the present invention provides a method for preparing borophene@MOF two-dimensional nanosheets, comprising the steps of:

[0032] Step S10: mixing the boron-containing multi-layered material, the organic ligand and the acid solution to obtain a mixed solution;

[0033] Step S20: subjecting the mixed solution to a solvothermal reaction to obtain borophene@MOF two-dimensional nanosheets.

[0034] In this embodiment, the metal in the boron-containing multi-layered material is used as a metal source under the combined action of an organic ligand and an acid solution to achieve a direct transition from the boron-containing multi-layered material to a two-dimensional borophene@MOF heterostructure. The preparation process is simple, greatly reducing the cost, and the preparation process is efficient, which can maximize the utilization and conversion of elements in the boron-containing multi-layered material. In addition, the borophene@MOF two-dimensional nanosheets prepared by the preparation method support each other to construct a reasonable heterostructure, reduce the basic resistance of the composite material, and show excellent NO2 gas sensing performance at room temperature.

[0035] Specifically, the present invention promotes the dissolution of metal elements in multi-layered materials and their transformation into MOFs through the synergy of organic ligands and acids, thereby realizing the construction of composite materials of MOF and two-dimensional substrates; the preparation method adopts a one-pot synthesis, which greatly reduces the time cost compared to composite materials prepared in multiple steps, and compared to the strategy of self-assembly after etching, it avoids the loss of metal elements in boron-containing multi-layered materials, maximizes the utilization of metal elements, and saves the cost and resource waste caused by the additional introduction of solvent waste liquid. In addition, in the process of in-situ construction of MOF / two-dimensional material heterojunction using the preparation method, the two-dimensional material and MOF are born together, so that they are tightly and evenly compounded together to form a three-dimensional sheet structure assembled by two-dimensional MOF nanosheets and two-dimensional material nanosheets, so that the prepared boronene@MOF two-dimensional nanosheets have a faster response speed and a higher response value to NO2.

[0036] In some embodiments, the boron-containing multi-layered material is selected from one or more of AlB2, MgB2, FeAlB, MoAlB, and WAlB. Under the combined action of organic ligands and acid solution, the metal in the boron-containing multi-layered material can be used as a metal source to achieve a direct transformation from the boron-containing multi-layered material to a two-dimensional borene@MOF heterostructure.

[0037] In a preferred embodiment, the boron-containing multi-layered material is AlB2.

[0038] In some embodiments, the organic ligand is selected from one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, imidazole, trimesic acid, 2,5-dihydroxyterephthalic acid, terephthalic acid, oxalic acid, and phthalic acid.

[0039] In a preferred embodiment, the organic ligand is 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin.

[0040] Specifically, the above-mentioned organic ligand and the acid solution can play a synergistic role, so that the metal elements in the multi-layered material are dissolved and transformed into MOF, thereby realizing the construction of a composite material of MOF and a two-dimensional substrate.

[0041] In some embodiments, the solute in the acid solution is selected from one or more of formic acid, hydrochloric acid, acetic acid, and sulfuric acid. The above acid can play a synergistic role with the organic ligand, which is conducive to promoting the dissolution of metal elements in the multi-layered material and the transformation to MOF, thereby realizing the construction of a composite material of MOF and a two-dimensional substrate.

[0042] In some embodiments, the mass ratio of the boron-containing multi-layered material to the organic ligand is 1:(1-8). The mass ratio of the boron-containing multi-layered material to the organic ligand is controlled within the above range, and combined with the "one-pot method" to synthesize the boronene@MOF two-dimensional nanosheet in one step, so that the two-dimensional material and MOF are co-existing, and thus are closely and evenly compounded together to form a three-dimensional sheet structure assembled by the two-dimensional MOF nanosheet and the two-dimensional material nanosheet, so that the material has a faster response speed and a higher response value to NO2.

[0043] In a preferred embodiment, the mass ratio of the boron-containing multi-layered material to the organic ligand is 1:(1-3) or 1:(5-8) to satisfy the coordination of all metal atoms as much as possible.

[0044] In some embodiments, the volume ratio of the solute in the acid solution to the solvent in the acid solution is (5-10): 1. The concentration of the acid solution is reasonably controlled to avoid the loss of metal elements in the layered material as much as possible, to maximize the utilization of metal elements, and to avoid excessive introduction of solvents to increase costs and waste resources.

[0045] In a preferred embodiment, the volume ratio of the solute in the acid solution to the solvent in the acid solution is 8:1, so as to etch the metal atoms in the boron-containing multi-layered material as much as possible and keep the nucleation and growth of MOF not inhibited.

[0046] In some embodiments, the solvothermal reaction temperature is 150°C-200°C, and the solvothermal reaction time is 6h-24h. Under the solvothermal reaction conditions, the forward reaction can be promoted and a high-crystallinity MOF can be obtained to obtain borophene@MOF two-dimensional nanosheets.

[0047] In a preferred embodiment, the temperature of the solvent thermal reaction treatment is 180° C., and the time of the solvent thermal reaction treatment is 15 hours.

[0048] In some embodiments, in step S20, after the solvent thermal reaction treatment, the product is further centrifuged, washed, and dried. Specifically, DMF and ethanol are used for washing; the temperature of the drying treatment is 60°C-80°C.

[0049] In addition, the present application also provides a borophene@MOF two-dimensional nanosheet, which is prepared using the preparation method of the borophene@MOF two-dimensional nanosheet.

[0050] In this embodiment, the borophene@MOF two-dimensional nanosheets prepared by this method support each other to construct a reasonable heterostructure, reduce the basic resistance of the composite material, and show excellent NO2 gas sensing performance at room temperature. In the process of in-situ construction of MOF / two-dimensional material heterojunction using this preparation method, the two-dimensional material and MOF are born together, so that they are tightly and evenly compounded together to form a three-dimensional sheet structure assembled by two-dimensional MOF nanosheets and two-dimensional material nanosheets, so that the prepared borophene@MOF two-dimensional nanosheet has a faster response speed and a higher response value for NO2. In addition, the present invention uses a simple solvothermal method to prepare MOF / two-dimensional material composite materials. The method is simple, low-cost and can achieve large-scale preparation, and can also achieve rapid preparation of MOF / two-dimensional material composite materials.

[0051] In addition, the present invention also provides a gas sensor, comprising a ceramic sheet printed with interdigital electrodes, and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is made of the borophene@MOF two-dimensional nanosheet.

[0052] In this embodiment, the borophene@MOF two-dimensional nanosheet is used as the gas sensing sensitive layer of the gas sensor. Thanks to the high porosity and large specific surface area of ​​MOF and the enhanced electron transfer of the composite in the gas sensing process after the composite borophene, it can respond and recover quickly at room temperature, and has broad application prospects in detecting NO2. In addition, the gas sensor has a simple preparation process, a small volume, and easy film formation of materials, which is easy to achieve commercial application.

[0053] In some embodiments, the thickness of the gas sensing sensitive layer is 1.5 mm-4 mm.

[0054] At the same time, the present invention also provides an application of a gas sensor in a device for detecting nitrogen dioxide.

[0055] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0056] Example 1

[0057] This embodiment provides a borophene@Al-PMOF, and the preparation steps are as follows:

[0058] AlB2 and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) powders in a mass ratio of 1:2 were weighed and placed in the polytetrafluoroethylene liner of the reactor, and a DMF / formic acid mixed solvent in a mass ratio of 7:1 was added to fully disperse them. The reactor was then transferred to an oven for solvothermal reaction at 180°C for 12 hours. After cooling naturally, the product was collected by centrifugation, washed with DMF and ethanol respectively, and dried in an oven at 60°C, which was recorded as borophene@Al-PMOF.

[0059] The borophene@Al-PMOF prepared in this example was characterized, and its XRD pattern is shown in Figure 2 As shown, the diffraction peak of the material corresponds to the MOF fitting peak, which proves the occurrence of the reaction and the successful preparation of the corresponding MOF.

[0060] The borophene@Al-PMOF prepared in this embodiment was etched to remove MOF, and then characterized. The XRD pattern is as follows: Figure 3 As shown, the existence of borophene is proved.

[0061] AlB2, the products after 0.5h, 3h, and 12h of reaction, and the borophene@Al-PMOF obtained after 12h of reaction were characterized. The SEM and TEM images are shown in Figure 4 As shown, (a)-(d) in the figure are SEM images, (e)-(h) are transmission electron microscope images; Figure 4 It can be seen that (a) in the figure is the initial morphology of AlB2, showing a blocky morphology; (b) as the reaction proceeds to 0.5h, the sample surface is etched to produce many tips; (c) as the reaction proceeds to 3h, many MOF nanosheets grow on the tip surface; (d) the nanosheets continue to grow and eventually form a hollow tubular structure; Figure 4 From (e)-(h), we can see that the nanosheets belong to MOF, while the wrinkled ones belong to two-dimensional borophene nanosheets.

[0062] Example 2

[0063] This embodiment provides a borophene@MIL-53, and the preparation steps are as follows:

[0064] AlB2 and terephthalic acid powders with a mass ratio of 1:2 were weighed and placed in a polytetrafluoroethylene liner, and a DMF / formic acid mixed solvent with a mass ratio of 7:1 was added to fully disperse them. The reactor was then transferred to an oven for solvothermal reaction at 180°C for 15 hours. After cooling naturally, the product was collected by centrifugation, washed with DMF and ethanol respectively, and dried in an oven at 60°C, and recorded as borophene@MIL-53.

[0065] The borophene@MIL-53 prepared in this example was characterized, and its XRD pattern is shown as follows: Figure 5As shown, the diffraction peak of the material corresponds to the MOF fitting peak, which proves the occurrence of the reaction and the successful preparation of the corresponding MOF.

[0066] Example 3

[0067] This embodiment provides a borophene@Mg-MOF-74, and the preparation steps are as follows:

[0068] AlB2 and 2,5-dihydroxyterephthalic acid powders with a mass ratio of 1:2 were weighed and placed in a polytetrafluoroethylene liner, and a DMF / formic acid mixed solvent with a mass ratio of 7:1 was added to fully disperse them. The reactor was then transferred to an oven for solvothermal reaction at 180°C for 15 hours. After cooling naturally, the product was collected by centrifugation, washed with DMF and ethanol respectively, and dried in an oven at 60°C, and recorded as borophene@Mg-MOF-74.

[0069] The borophene@Mg-MOF-74 prepared in this example was characterized, and its XRD pattern is shown in Figure 6 As shown, the diffraction peak of the material corresponds to the MOF fitting peak, which proves the occurrence of the reaction and the successful preparation of the corresponding MOF.

[0070] Example 4

[0071] The preparation of a gas sensor using the borophene@Al-PMOF prepared in Example 1 comprises the following steps:

[0072] The ceramic sheet printed with silver-palladium interdigital electrodes was ultrasonically cleaned in acetone, water and ethanol for 30 min each, and then dried in an oven at 60°C for subsequent testing.

[0073] A certain amount of sample was dispersed in deionized water and ultrasonically dispersed to form a uniform solution of 10 mg / mL.

[0074] Use a pipette to take 40 μL of evenly dispersed sample and drop it on the silver palladium interdigital electrode to form a gas sensing sensitive layer about 2 mm thick. After drying at room temperature, test it in air and nitrogen dioxide atmospheres to test its resistance changes in different atmospheres; the room temperature sensing performance data of the gas sensor device for 10 ppm NO2 at room temperature is shown in the figure Figure 7 As shown in the figure, it shows that it has good nitrogen dioxide gas sensing performance at room temperature. In the response process to nitrogen dioxide at a concentration of 10ppm, it shows a response time of 23s and a fast recovery of 276s in air atmosphere. The selectivity test data of the interfering gas is shown in the figure Figure 8 As shown, the response value of the sample to nitrogen dioxide is 375%, which is extremely high selectivity compared to other gases.

[0075] In summary, the present invention provides a borophene@MOF two-dimensional nanosheet and its preparation method, gas sensor and application, including the steps of: mixing a boron-containing multi-layered material, an organic ligand and an acid solution to obtain a mixed solution; subjecting the mixed solution to a solvent thermal reaction treatment to obtain a borophene@MOF two-dimensional nanosheet. The present invention realizes the transformation from a boron-containing multi-layered material directly to a two-dimensional borophene@MOF heterostructure by using the metal in the boron-containing multi-layered material as a metal source through the combined action of an organic ligand and an acid solution. The preparation process is simple, greatly reducing the cost, and the preparation process is efficient, which can maximize the utilization and conversion of elements in the boron-containing multi-layered material. In addition, the borophene@MOF two-dimensional nanosheets prepared by the preparation method support each other to construct a reasonable heterostructure, reduce the basic resistance of the composite material, and exhibit excellent NO2 gas sensing performance at room temperature.

[0076] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing borophene@MOF two-dimensional nanosheets, characterized in that: Includes steps: Mixing the boron-containing multi-layered material, the organic ligand and the acid solution to obtain a mixed solution; The mixed solution is subjected to a solvothermal reaction treatment to obtain borophene@MOF two-dimensional nanosheets.

2. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The boron-containing multi-layered material is selected from one or more of AlB2, MgB2, FeAlB, MoAlB, WAlB, etc.

3. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The organic ligand is selected from one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, imidazole, trimesic acid, 2,5-dihydroxyterephthalic acid, terephthalic acid, oxalic acid, and phthalic acid.

4. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The solute in the acid solution is selected from one or more of formic acid, hydrochloric acid, acetic acid and sulfuric acid.

5. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The mass ratio of the boron-containing multi-layered material to the organic ligand is 1:(1-8).

6. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The volume ratio of the solute in the acid solution to the solvent in the acid solution is (5-10):

1.

7. The method for preparing borophene@MOF two-dimensional nanosheets according to claim 1, characterized in that: The temperature of the solvent thermal reaction treatment is 150° C.-200° C., and the time of the solvent thermal reaction treatment is 6 h-24 h.

8. A borophene@MOF two-dimensional nanosheet, characterized in that: The borophene@MOF two-dimensional nanosheet is prepared by the preparation method of any one of claims 1 to 7.

9. A gas sensor, characterized in that: It comprises a ceramic sheet printed with interdigital electrodes, and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is made of the borophene@MOF two-dimensional nanosheet as described in claim 8.

10. Use of the gas sensor according to claim 9 in a device for detecting nitrogen dioxide.

Images