阅读说明：本技术 一种基于硼纳米片多级结构微米材料及其制备方法和应用 (Boron nanosheet multilevel structure-based micron material and preparation method and application thereof ) 是由 黄晓 李绍周 詹洪凤 董孟玮 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种基于硼纳米片多级结构微米材料的制备方法及其在湿度传感检测方面的应用,属于纳米材料制备技术领域。首先以甲基化硼纳米片为基础,通过真空冷冻干燥法结合模板法制备了具有三维结构的硼基空心球和一维结构的硼基微米带；其次将所制备的三维硼基空心球和一维硼基微米带的甲醇溶液旋涂在金交叉电极上,金交叉电极表面仅露出两端电极,其余部位被传感材料覆盖,制得湿度检测范围为43％RH-97％RH的湿度传感器。(The invention discloses a preparation method of a micron material based on a boron nanosheet multilevel structure and application of the micron material in humidity sensing detection, and belongs to the technical field of nano material preparation. Firstly, preparing a boron-based hollow sphere with a three-dimensional structure and a boron-based micro-strip with a one-dimensional structure by using a methylated boron nanosheet as a base through a vacuum freeze-drying method in combination with a template method; and secondly, coating the prepared three-dimensional boron-based hollow spheres and a methanol solution of the one-dimensional boron-based micron band on a gold cross electrode in a spinning way, wherein only electrodes at two ends are exposed on the surface of the gold cross electrode, and the rest parts are covered by a sensing material, so that the humidity sensor with the humidity detection range of 43-97% RH is prepared.)

1. A method for preparing a three-dimensional boron-based hollow sphere based on a boron nanosheet multilevel structure humidity sensing material is characterized by comprising the following steps of: the method comprises the following steps:

(1) at room temperature, dissolving the synthesized boron methylation nanosheet in water, shaking to enable the product to react fully, and visible H₂Generating bubbles;

(2) centrifuging at low rotation speed by centrifugal precipitation method, and collecting upper layer solution containing more bubbles;

(3) and (3) pre-freezing the upper layer solution obtained in the step (2) in liquid nitrogen, and carrying out vacuum freeze drying to obtain the boron-based hollow sphere with the three-dimensional structure.

2. The preparation method of the three-dimensional boron-based hollow sphere based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 1, wherein the preparation method comprises the following steps: the preparation method of the boron methylation nanosheet in the step (1) is characterized in that magnesium boride, concentrated hydrochloric acid, methanol and iodine are used as raw materials and are synthesized by an organic synthesis method.

3. The preparation method of the three-dimensional boron-based hollow sphere based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 1, wherein the preparation method comprises the following steps: in the step (1), the reaction temperature is 25-28 ℃, and the molar ratio of the boron methylation nanosheet to the water is 0.005-1: 1; the centrifugation speed in the step (2) is 5000-8000 turns, and the centrifugation time is 5-10 minutes.

4. The preparation method of the three-dimensional boron-based hollow sphere based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 1, wherein the preparation method comprises the following steps: the specific vacuum freeze drying conditions in the step (3) are as follows: pre-freezing the mixture in liquid nitrogen at a low temperature (-196 ℃) for 5-10 minutes, and freeze-drying the mixture in vacuum for 24-48 hours.

5. The preparation method of the three-dimensional boron-based hollow sphere based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 1, wherein the preparation method comprises the following steps: in the step (1), the reaction temperature is 26 ℃, and the molar ratio of the boron methylation nanosheet to the water is 0.005: 1; the centrifugation speed in the step (2) is 5000 revolutions, and the centrifugation time is 5 minutes; in the step (3), the pre-freezing time is 10 minutes during vacuum freeze drying, and the freeze-drying time is 24 hours during vacuum freeze drying.

6. A method for preparing a one-dimensional boron-based micron band based on a boron nanosheet multilevel structure humidity sensing material is characterized by comprising the following steps of: the method comprises the following steps:

(1) dissolving the synthesized boron methylation nanosheet in water at room temperature, and shaking to enable the product to react fully;

(2) centrifuging the uniformly dispersed solution at a low rotation speed by adopting a centrifugal precipitation method, and taking the upper-layer solution to obtain smaller methylated boron nanosheets;

(3) centrifuging the supernatant obtained in step (2) at high rotation speed by centrifugal precipitation, and removing the precipitate to remove H₂Bubbling, and re-dispersing the obtained precipitate in certain deionized water.

(4) And (4) pre-freezing the solution obtained in the step (3) in liquid nitrogen, and carrying out vacuum freeze drying to obtain the boron-based micro-strip with the one-dimensional structure.

7. The method for preparing the one-dimensional boron-based micron band based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 6, wherein: the preparation method of the boron-based nanosheet in the step (1) is characterized in that magnesium boride, concentrated hydrochloric acid, methanol and iodine are used as raw materials and are synthesized by an organic synthesis method;

in the step (1), the reaction temperature is 25-28 ℃, and the molar ratio of the boron nanosheets to the water is 0.005-1: 1;

the centrifugation speed in the step (2) is 5000-8000 revolutions, and the centrifugation time is 5-10 minutes;

the centrifugation speed in the step (3) is 12000-13000 revolutions, and the centrifugation time is 5-10 minutes;

the specific vacuum freeze drying conditions in the step (4) are as follows: pre-freezing the mixture in liquid nitrogen at a low temperature (-196 ℃) for 5-10 minutes, and freeze-drying the mixture in vacuum for 24-48 hours.

8. The method for preparing the one-dimensional boron-based micron band based on the humidity sensing material with the boron nanosheet multilevel structure according to claim 6, wherein: in the step (1), the reaction temperature is 26 ℃, and the molar ratio of the boron nanosheet to the water is 0.005: 1; the centrifugation speed in the step (2) is 5000 revolutions, and the centrifugation time is 5 minutes; the centrifugation speed in the step (3) is 12000 revolutions, and the centrifugation time is 5 minutes; in the step (4), the pre-freezing time during vacuum freeze drying is 10 minutes, and the freeze-drying time during vacuum freeze drying is 24 hours.

9. The boron-based hollow sphere with a three-dimensional structure or the boron-based micro-strip with a one-dimensional structure prepared by the preparation method according to claim 1 or 6.

10. The use of boron-based hollow spheres with a three-dimensional structure or boron-based micro-ribbons with a one-dimensional structure according to claim 9, wherein: the application of the humidity sensor is used for humidity detection with the range of 43% RH-97% RH.

Technical Field

The invention relates to a preparation method and application of a micron material based on a boron nanosheet multilevel structure.

Background

The multilevel structure micro-nano material is a material with the size in a micro or nano range formed on the basis of a low-dimensional nano material according to a specific arrangement or self-assembly mode. Compared with a low-dimensional nano material, the multi-level structure micro-nano material not only can keep excellent physical and chemical properties of the nano material, but also can show special properties superior to a single nano material, such as high specific surface area, high surface activity and the like. Meanwhile, the macroscopic scale reaches the micron level, and the defects of unstable structure, easy agglomeration and the like of the low-dimensional nano material are overcome. The research of the multilevel-structure micro-nano material has very important significance for the development of material performance, the construction of novel functional devices and the like.

The boron alkene has excellent physical and chemical properties, so that the boron alkene has wide application prospects in the fields of energy storage, sensing, fuel cells, super capacitors and the like. Currently, generally known preparation of borolene is mostly focused on the design and construction of two-dimensional borolene, and various structures such as one-dimensional micron bands, nanotubes, nanowires, three-dimensional porous hollow spheres and the like are not prepared and researched yet. Like most two-dimensional materials, boronenes are also prone to agglomeration, limiting their application in the field of electrochemical sensing devices. The shape and physical size of the low-dimensional nano material are orderly designed, and the low-dimensional nano material is constructed into a multi-level structure micro-nano material, so that the defect can be overcome. However, there are few studies on the boron-ene multilevel structure, and the properties thereof have not been studied.

In recent years, a humidity sensing two-dimensional material represented by graphene oxide has been widely used in the field of humidity sensors due to its advantages of relatively large surface area, many active sites, strong water molecule adsorption capacity, and the like. As a graphene-like material, the boron alkene has the characteristics of excellent electrical property, abundant surface chemical activity and the like, and has a wide application prospect in the sensing field. However, the special electron-deficient structure of boron atoms makes the currently prepared boron alkene extremely unstable under environmental conditions, further limiting the application of boron alkene in the field of humidity sensing. Currently, research on the application of boron alkene in humidity sensing is still less.

The two-dimensional methylated boron nanosheets are successfully constructed into boron-based micron belts with one-dimensional structures and boron-based hollow spheres with three-dimensional structures by combining a vacuum freeze-drying method and a template method; and the humidity sensors based on the three-dimensional boron-based hollow spheres and the one-dimensional boron-based micron band are prepared, and compared with most of reported two-dimensional material humidity sensors, the two humidity sensors have the characteristics of ultrahigh sensitivity, shorter response and recovery time and the like. Humidity sensing performance is at the forefront of humidity sensing materials currently under study.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method and application of a boron nanosheet based multi-level structure material. The two-dimensional methylated boron nanosheets are constructed into boron-based micro-strips with one-dimensional structures and boron-based hollow spheres with three-dimensional structures, the surfaces of the boron-based micro-strips and the boron-based hollow spheres both contain rich oxygen-containing functional groups, so that the humidity sensing performance of the boron-based hollow spheres is improved, and the boron-based hollow spheres are used for preparing humidity sensors.

The technical scheme provided for solving one of the technical problems is as follows: a preparation method of a boron-based hollow sphere micron material based on a boron nanosheet three-dimensional structure is characterized by comprising the following steps of: the method comprises the following steps:

(1) at room temperature, dissolving the synthesized boron methylation nanosheet in water, shaking to enable the product to react fully, and visible H₂Generating bubbles;

(2) centrifuging at low rotation speed by centrifugal precipitation method, and collecting upper layer solution containing more bubbles;

(3) and (3) carrying out vacuum freeze drying on the upper layer solution obtained in the step (2) to obtain the boron-based hollow sphere with a three-dimensional structure.

Preferably, the preparation method of the nanosheet in the step (1) is to use magnesium boride, concentrated hydrochloric acid, methanol and iodine as raw materials and synthesize the nanosheet by an organic synthesis method.

Preferably, in the step (1), the reaction temperature is 25-28 ℃, and the molar ratio of the boron methylation nanosheet to the water is 0.005-1: 1.

Preferably, the centrifugation speed in the step (2) is 5000-8000 revolutions, and the centrifugation time is 5-10 minutes.

Preferably, the vacuum freeze-drying in step (3) specifically comprises the following conditions: pre-freezing the mixture in liquid nitrogen at a low temperature (-196 ℃) for 5-10 minutes, and freeze-drying the mixture in vacuum for 24-48 hours.

Preferably, in the step (1), the reaction temperature is 26 ℃, and the molar ratio of the boron methylation nanosheets to the water is 0.005: 1; the centrifugation speed in the step (2) is 5000 revolutions, and the centrifugation time is 5 minutes; in the step (3), the pre-freezing time is 10 minutes during vacuum freeze drying, and the freeze-drying time is 24 hours during vacuum freeze drying.

The technical scheme provided for solving one of the technical problems is as follows: a preparation method of a boron-based micron band based on a boron nanosheet one-dimensional structure is characterized by comprising the following steps: the method comprises the following steps:

(1) dissolving the synthesized boron methylation nanosheet in water at room temperature, and shaking to enable the product to react fully;

(2) centrifuging the uniformly dispersed solution at a low rotation speed by adopting a centrifugal precipitation method, and taking the upper-layer solution to obtain smaller methylated boron nanosheets;

(3) centrifuging the supernatant obtained in step (2) at high rotation speed by centrifugal precipitation, and removing the precipitate to remove H₂Bubbling, and re-dispersing the obtained precipitate in certain deionized water.

(4) And (4) carrying out vacuum freeze drying on the solution obtained in the step (3) to obtain the boron-based micron band with a one-dimensional structure.

Preferably, the preparation method of the nanosheet in the step (1) is to use magnesium boride, concentrated hydrochloric acid, methanol and iodine as raw materials and synthesize the nanosheet by an organic synthesis method.

Preferably, in the step (1), the reaction temperature is 25-28 ℃, and the molar ratio of the boron methylation nanosheet to the water is 0.005-1: 1.

Preferably, the centrifugation speed in the step (2) is 5000-8000 revolutions, and the centrifugation time is 5-10 minutes.

Preferably, the centrifugation speed in the step (3) is 12000-13000 revolutions, and the centrifugation time is 5-10 minutes.

Preferably, the vacuum freeze-drying in step (4) comprises the following specific conditions: pre-freezing the mixture in liquid nitrogen at a low temperature (-196 ℃) for 5-10 minutes, and freeze-drying the mixture in vacuum for 24-48 hours.

Preferably, in the step (1), the reaction temperature is 26 ℃, and the molar ratio of the boron methylation nanosheets to the water is 0.005: 1; the centrifugation speed in the step (2) is 5000 revolutions, and the centrifugation time is 5 minutes; the centrifugation speed in the step (3) is 12000 revolutions, and the centrifugation time is 5 minutes; in the step (4), the pre-freezing time during vacuum freeze drying is 10 minutes, and the freeze-drying time during vacuum freeze drying is 24 hours.

The technical scheme provided for solving one of the technical problems is as follows: the materials can be applied to humidity sensing.

Preferably, the three-dimensional boron-based hollow spheres and the one-dimensional boron-based micron band are dropped on the surface of the gold cross electrode and dried in the natural air, and the prepared electrode can test the humidity under different relative humidity environments at normal temperature.

In the preparation method based on the boron nanosheet multilevel structure material, the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band can be applied to the field of humidity sensing.

And respectively spin-coating 1 microliter of three-dimensional boron-based hollow sphere or one-dimensional boron-based micron band solution on the surface of the gold cross electrode, and drying in the natural air to obtain the electrode for testing different relative humidities at normal temperature.

The invention has the beneficial effects that:

after the size and the morphology of the methylated boron nanosheet are constructed, the obtained three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band can provide a large specific surface area and more adsorption sites, and meanwhile, the surfaces of the two materials are rich in oxygen-containing functional groups, which are beneficial to the interaction with water molecules, so that the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band can be used for preparing a humidity sensor.

1. The preparation of the boron-based hollow sphere with the three-dimensional structure and the boron-based micron band with the one-dimensional structure improves the stability and the specific surface area of the material.

2. The boron-based hollow sphere with the three-dimensional structure and the boron-based micron band humidity sensor with the one-dimensional structure can detect the humidity under different relative humidity environments at room temperature.

3. The boron-based hollow sphere with the three-dimensional structure and the boron-based micron band humidity sensor with the one-dimensional structure have the characteristics of ultrahigh sensitivity, shorter response and recovery time and the like in the detection of humidity.

4. After the methylated boron nanosheet is mixed with water, surface reaction can occur to generate a small amount of boric acid and release H₂Gas (see reaction equation: 2B + 6H)₂O→2B(OH)₃+3H₂↑)。H₂Gas bubbles form due to low solubility in aqueous solutions. The surface energy of the methylated boron nanosheet is higher after the reaction with water, the interface energy is minimized as the driving force, and the methylated boron nanosheet is easy to be in H₂The surface of the bubbles coalesces to form spherical agglomerates. Subsequently, in the liquid nitrogen vacuum freeze drying process, freezing of water further extrudes the boron methylation nanosheets into H₂Around the air bubble. In addition, because the surface of the boron methylation nanosheet is provided with hydroxyl after the reaction with water, the nanosheets are easily bonded together through a polycondensation reaction. Finally forming the three-dimensional boron-based hollow sphere.

5. In the vacuum freeze-drying process, the morphology of the product can be controlled by the size and shape of the ice crystals, which in turn can be controlled by adjusting the freezing rate. When the nano-sheets are slowly cooled and crystallized in a refrigerator at the temperature of-10 ℃, the lower nucleation and growth rate of ice crystals and the longer crystallization period result in larger ice crystals and more two-dimensional plane grain boundaries, and wider micron bands or broken micron sheets are formed after the ice crystals are sublimated; when the nano-sheets are rapidly frozen in liquid nitrogen at the temperature of-196 ℃, a large amount of narrower ice crystals are generated due to higher ice crystal nucleation and growth rate, and the nano-sheets are limited by more one-dimensional grain boundary spaces, so that the one-dimensional boron-based micron band is prepared.

Drawings

The invention will be further explained with reference to the drawings.

Fig. 1 is an SEM image of the three-dimensional boron-based hollow sphere in example 1.

FIG. 2 is a diameter distribution diagram of a three-dimensional boron-based hollow sphere in example 1.

FIG. 3 is an FTIR chart of the three-dimensional boron-based hollow sphere of example 1.

FIG. 4 is an SEM image of one-dimensional boron-based micron ribbon of example 2.

FIG. 5 is a graph of the distribution of the width diameters of one-dimensional boron-based nanobelts in example 2.

FIG. 6 is a FTIR plot of one-dimensional boron-based micro-ribbons from example 2.

Fig. 7 is a dynamic response diagram of the three-dimensional boron-based hollow sphere humidity sensor in embodiment 3 under different humidity environments.

Fig. 8 is a dynamic response diagram of the one-dimensional boron-based micro-strip humidity sensor in example 3 under different humidity environments.

FIG. 9 is a graph showing the sensitivity of two humidity sensors in example 3 under different humidity environments.

Fig. 10 is a graph of response and recovery time of the three-dimensional boron-based hollow sphere humidity sensor in example 3 under different humidity environments.

Fig. 11 is a graph of response and recovery time of the one-dimensional boron-based micro-strip humidity sensor in example 3 under different humidity environments.

Detailed Description

For a better understanding of the present invention, the technical solutions of the present invention will be described in detail below by way of specific embodiments with reference to the accompanying drawings.

Example 1: preparation method of three-dimensional boron-based hollow sphere based on boron nanosheet multilevel structure material

Weighing 0.005g of boron methylation nanosheet, putting the boron methylation nanosheet into a 2mL centrifuge tube filled with 1mL deionized water, shaking to enable the product to react fully, allowing obvious hydrogen bubbles to be seen, centrifuging the uniformly dispersed solution at 5000rpm for 5min, and taking the upper layer bubble-containing solution. The solution is pre-frozen in liquid nitrogen at low temperature (-196 ℃) for 5 minutes, then the pre-frozen solution is put into a vacuum freeze dryer to be frozen for 24 hours, and the three-dimensional boron-based hollow sphere is obtained after being taken out at room temperature.

Analyzing the product in example 1, as shown in fig. 1, an SEM image of the three-dimensional boron-based hollow sphere can show that the obtained product has a three-dimensional hollow sphere structure;

analyzing the product in example 1, as shown in fig. 2, the diameter distribution diagram of the three-dimensional boron-based hollow sphere can show that the boron-based hollow sphere is in micron level;

analyzing the product of example 1, as shown in fig. 3, an FTIR diagram of the three-dimensional boron-based hollow sphere can show that the surface of the three-dimensional boron-based hollow sphere has a large amount of oxygen-containing functional groups;

example 2: preparation method of one-dimensional boron-based micron band based on boron nanosheet multi-level structural material

Weighing 0.005g of boron methylation nanosheet, placing the boron methylation nanosheet into a 2mL centrifuge tube filled with 1mL deionized water, and shaking to enable the product to react fully. Centrifuging the uniformly dispersed solution at 5000rpm for 5min, taking the upper layer solution to obtain smaller methylated boron nanosheets, centrifuging at 12000rpm for 10min, taking the lower layer precipitate to remove H₂Air bubbles. The obtained precipitate is re-dispersed in 1mL of deionized water, pre-frozen in liquid nitrogen at-196 ℃ for 5 minutes, then the pre-frozen lower layer mixed solution is put into a vacuum freeze dryer to be frozen for 24 hours, and then taken out at room temperature to obtain the one-dimensional boron-based micron band.

The product in example 2 is analyzed, and as shown in fig. 4, an SEM image of a one-dimensional boron-based micron band can be used to show that the obtained product is a micron band with a one-dimensional structure;

analyzing the product in example 2, as shown in fig. 5, the width diameter distribution diagram of the one-dimensional boron-based micron band can indicate that the boron-based micron band is in micron level through the width diameter distribution diagram;

analyzing the product in example 2, as shown in fig. 6, an FTIR diagram of a one-dimensional boron-based micro-strip can show that the surface of the one-dimensional boron-based micro-strip has a large amount of oxygen-containing functional groups;

example 3: method for preparing humidity sensor based on boron nanosheet multilevel structure material

(1) 5 mg of the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band are respectively dispersed in 500 microliters of methanol solution to prepare corresponding concentrated dispersion liquid. Uniformly dripping the concentrated dispersion liquid of the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band on a cleaned interdigital electrode, dripping the concentrated dispersion liquid on a gold cross electrode, naturally drying to form a film, only exposing two end electrodes on the surface of the gold cross electrode, and covering the rest parts with sensing materials to obtain the humidity sensor based on the two materials.

(2) Preparing the humidity required for the experiment with a composition containing K₂CO₃NaBr, NaCl and K₂SO₄The saturated salt solutions of (a) were prepared at relative humidities of 43%, 57%, 75% and 97%, respectively. Under the condition of room temperature, the relative humidity of the air above the metal salt saturated solution is certain (at room temperature, the relative humidity of the air above the NaBr saturated solution is 57% RH), nitrogen is used as carrier gas, water vapor above the NaCl saturated solution is carried into an air chamber of a probe table, and the water vapor amount entering the air chamber of the probe table is controlled by adjusting the flow of the nitrogen, so that the relative humidity required by an experiment can be obtained.

(3) The device is placed in a probe station container, two probes of the probe station are respectively connected with a source electrode and a drain electrode of the device, at the moment, the other ends of the probes are connected with a 4200-SCS instrument, 1V bias voltage is applied to the device, current change values of the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band in the external humidity change process can be respectively tested, and the relative humidity interval in the test process is 43% -RH-97% RH.

Example 4: application of three-dimensional boron-based hollow sphere and one-dimensional boron-based micron band humidity sensor in testing different relative humidity

(1) The humidity sensor modified with the three-dimensional boron-based hollow spheres and the one-dimensional boron-based micron band is placed in an air chamber of a probe station, the humidity sensor is communicated with the probe and is connected to a 4200-SCS semiconductor parameter instrument in parallel, required humidity is introduced right above the sensor at normal temperature, and the parameter instrument is used for testing the sensing performance of different humidity.

(2) Introducing pure nitrogen, and measuring the baseline current I of the humidity sensor when the relative humidity is not introduced₀。

(3) And measuring the current I when nitrogen is used as carrier gas to carry different relative humidity, wherein the humidity detection interval is gradually increased from 43% RH to 97% RH.

(4) In each humidity environment, the current of the sensor changes with the increase of humidity, and then self-recovers.

(5) Conversion of the measured current into Δ I/I₀In which I₀Is the baseline current when no relative humidity is applied and ar is the maximum value of the change in current relative to the baseline current when relative humidity is applied.

(6) Will be delta I/I₀Plotting time, as humidity increases, the current change value increases accordingly.

The test results are analyzed, as shown in fig. 7, the dynamic response diagram of the three-dimensional boron-based hollow sphere sensor in different humidity environments shows that the current value in the diagram increases with the increase of humidity, and the overall change of the dynamic response curve tends to be stable, which indicates that the three-dimensional boron-based hollow sphere humidity sensor has better stability. As shown in fig. 8, in the dynamic response diagram of the one-dimensional boron-based micro-strip sensor in different humidity environments, the current value in the diagram increases with the increase of humidity, and the overall change of the dynamic response curve tends to be stable, which indicates that the one-dimensional boron-based micro-strip humidity sensor has better stability.

The test results are analyzed, as shown in fig. 9, the sensitivity diagrams of the two humidity sensors under different humidity environments are shown, and the response values of the humidity sensors increase along with the increase of the humidity. When the humidity is increased from 43% RH to 97% RH, the sensitivity of the three-dimensional boron-based hollow sphere sensor is up to 41200%, and the sensitivity of the one-dimensional boron-based micron band humidity sensor is 5200%, which indicates that the humidity sensor has higher sensitivity.

As shown in fig. 10, a graph of response and recovery time of the one-dimensional boron-based micron band humidity sensor in different humidity environments shows that the one-dimensional boron-based micron band humidity sensor has ultra-fast response time and recovery time, which indicates that the one-dimensional boron-based micron band humidity sensor has characteristics of fast response (7 s), short recovery time (3 s), and the like.

As shown in fig. 11, a response and recovery time diagram of the three-dimensional boron-based hollow sphere humidity sensor in different humidity environments shows that the humidity sensor has an ultra-fast response time and recovery time, which indicates that the three-dimensional boron-based hollow sphere humidity sensor has characteristics of fast response (28 s), short recovery time (2 s), and the like.

Therefore, the three-dimensional boron-based hollow sphere and the one-dimensional boron-based micron band can be used for preparing the humidity sensor and have excellent humidity sensing performance.

The invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent substitutions are within the scope of the invention as claimed.