Preparation method of two-dimensional boron hydride alkene

Abstract

The invention discloses a preparation method of two-dimensional boron hydride alkene, and belongs to the technical field of preparation of two-dimensional nano materials. The method comprises the following steps: dispersing metal boride and purified hydrogen type ion exchange resin in an organic solvent with a DN value of less than 19, and carrying out a sealed reaction under the protection of inert gas; according to the method, through the synergistic effect of the low-DN-value solvent and the purified resin, the ion exchange efficiency is effectively improved, competitive adsorption is avoided, the yield of the two-dimensional boron hydride is made to exceed 70%, and the method is mild in reaction condition, easy and convenient to operate, environmentally friendly and suitable for large-scale preparation.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional nanomaterial preparation technology, and more specifically, to a method for preparing two-dimensional boron hydride. Background Technology

[0002] Two-dimensional borophene oxide (2D HB) refers to two-dimensional borophene nanomaterials with a completely hydrogenated surface. Theoretically, 2D borophene oxide is a more stable derivative than two-dimensional borophene. Theoretical predictions indicate that 2D HB possesses excellent mechanical properties (131 N·m). -1 High Young's modulus), semi-metallic electrical conductivity, ultra-light density, and ultra-high thermal conductivity (335 W·mK). 1 It exhibits good environmental stability and can remain stable in an atmospheric environment at 400 K. Compared with other two-dimensional materials, two-dimensional C... mmn Two-dimensional hydroborenes possess unique chemical structures and physicochemical properties: their honeycomb network, with hydrogen atoms linked by BHB hydrogen bridges (B:H = 1:1), endows the material surface with abundant active adsorption sites, enabling efficient capture and binding of gases and other molecules in the environment. This results in a stronger adsorption capacity for gases and other molecules compared to two-dimensional materials with fewer surface active sites (such as graphene and MoS2). Furthermore, they exhibit solid electrolyte properties and excellent proton conductivity, making two-dimensional hydroborenes a promising candidate for applications in photoelectric detection, new energy storage, catalysis, and gas-sensitive detection.

[0003] Currently, methods for preparing two-dimensional hydroborenes include ion exchange, sodium borohydride thermal decomposition, and molecular beam epitaxy (MBE). Ion exchange not only produces a large number of difficult-to-remove oxidation byproducts but also uses volatile and highly toxic organic solvents, leading to significant experimental safety hazards and low yields. Sodium borohydride thermal decomposition uses sodium borohydride powder as a raw material, heated in a hydrogen environment to achieve large-area hydroborene preparation. However, sodium borohydride, a strongly reducing inorganic compound, reacts violently with water or in humid environments, releasing hydrogen gas, posing significant safety risks and making the reaction process too vigorous and difficult to control. Molecular beam epitaxy (MBE) is another commonly used method for growing two-dimensional hydroborenes. When preparing two-dimensional hydroborenes using MBE, two-dimensional borohydrides are first grown on a specific substrate using the MBE method. Subsequently, hydrogen gas is introduced for heat treatment, gradually transforming the two-dimensional borohydrides into two-dimensional hydroborenes. However, the planar size of two-dimensional boronene prepared by the MBE method is usually small (about 30 nm) and the yield is low. It also has problems such as being unable to exist stably after being removed from the growth substrate.

[0004] The prior art discloses a two-dimensional hydroborene HB material, which is experimentally prepared by exfoliation and complete ion exchange between protons and magnesium cations in magnesium diboride MgB2. The average yield at room temperature is 42.3%, and the yield is difficult to reach more than 70% even when heated to above 50℃. This cannot meet the requirements for large-scale preparation of two-dimensional hydroborene, and it is difficult to control the experimental conditions.

[0005] Therefore, developing a mild, easily controllable preparation method that can yield high-purity two-dimensional hydroborenes while improving yield is of significant research importance and application value. Summary of the Invention

[0006] To address the technical problems of low yield and difficulty in controlling conditions in the preparation methods of two-dimensional hydroborenes in the prior art, the primary objective of this invention is to provide a method for preparing two-dimensional hydroborenes.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing two-dimensional hydroborene includes the following steps: S1. Disperse the metal boride and the purified hydrogen-form ion exchange resin in an organic solvent, fill the container with inert gas, stir, and carry out a sealed reaction. S2. Centrifugation process yields the two-dimensional hydroborene; Wherein, the DN value of the organic solvent in step S1 is less than 19; The purified hydrogen-form ion exchange resin was obtained by soaking the hydrogen-form ion exchange resin in the organic solvent for 48-72 hours.

[0008] The inventors discovered that by using a low-DN organic solvent as a dispersant to prepare a dispersion of metal borides, and then adding a hydrogen-form ion exchange resin and magnetically stirring under specific temperature and rotation speed conditions, two-dimensional hydroborenes can be obtained. The principle is as follows: hydrogen ions ionized from the hydrogen-form ion exchange resin in the organic solution undergo an exchange reaction with magnesium ions in the metal boride. The hydrogen ions then undergo atomic reconstruction on the surface of the hexagonal boron network to form hydroborenes. During this reaction, the organic solvent intercalates the hydrogen ions ionized from the hydrogen-form ion exchange resin into the magnesium layer of magnesium diboride, and transports the magnesium ions released from the metal boride into the resin, where they finally combine with the electronegative functional group sulfonate. The core advantage of ion exchange resins purified with organic solvents is that they can completely remove residual small molecule oligomers, preventing them from entering the reaction system with organic solvents such as acetone. Combined with the Langmuir isothermal competitive adsorption theory, the number of active sites in the reaction system is fixed. Oligomers released from unpurified resin will compete with target ions for limited active sites, resulting in a reduction in the adsorption amount of target ions and incomplete reaction, with a boronene yield of only about 5%. However, purification eliminates this competitive interference, allowing target ions to fully occupy active sites and react efficiently with magnesium diboride, thus increasing the yield.

[0009] Furthermore, the preparation method of this invention allows for the control of the morphology and purity of two-dimensional hydroborenes by adjusting the temperature of the reaction solution. Additionally, this research has found that by selecting a polar organic solvent with a low DN value and utilizing a hydrogen-form ion exchange resin purified from the organic solvent, a high-yield preparation of two-dimensional hydroborenes can be achieved. The preparation method of this invention is a mild and environmentally friendly ion exchange process, achieving a yield of over 80% for two-dimensional hydroborenes, making it suitable for large-scale industrial production. The raw materials used in this invention are metal borides, hydrogen-form ion exchange resins, and low-DN organic solvents. This eliminates the need for additional reactants or catalysts, and avoids high-temperature and high-pressure reaction conditions, effectively reducing production costs and increasing the yield of two-dimensional hydroborenes.

[0010] Preferably, the ratio of the added metal boride, the purified hydrogen-form ion exchange resin, and the organic solvent in step S1 is 0.5~2 mg: 5 mL: 5 mL.

[0011] Preferably, the metal boride in step S1 is at least one of magnesium diboride, aluminum diboride, titanium diboride, or calcium hexaboride.

[0012] Preferably, the organic solvent in step S1 is at least one of solvents such as acetone, acetonitrile, and methanol.

[0013] Preferably, the temperature of the sealing reaction in step S1 is 5~50°C.

[0014] Preferably, the temperature of the sealing reaction in step S1 is 20~50℃.

[0015] Within this temperature range, it is more conducive to increasing the surface tension and polarity of the solvent, thereby improving the yield of two-dimensional hydroborene structures.

[0016] Preferably, the sealing reaction time in step S1 is 54~72 hours.

[0017] Preferably, the sealing reaction time in step S1 is 70-72 hours.

[0018] Within this time frame, it is more conducive to promoting the full reaction between the metal boride raw material and the hydrogen-form ion exchange resin, resulting in a higher purity of the prepared two-dimensional hydroborene product.

[0019] Preferably, the stirring speed in step S1 is 300~600 rpm.

[0020] Preferably, the stirring in step S1 is magnetic stirring.

[0021] Within this stirring speed range, it is more conducive to the thorough mixing of the reaction raw materials, while minimizing wear and tear on the hydrogen-form ion exchange resin.

[0022] Preferably, the centrifugation in step S2 includes two centrifugation processes. The conditions for the first centrifugation process are: a rotation speed of 500~1000 rpm and a time of 10~50 min, and the supernatant is collected. The conditions for the second centrifugation process are: a rotation speed of 10000~12000 rpm and a time of 5~10 min.

[0023] More preferably, the first centrifugation process is performed 1 to 5 times.

[0024] Preferably, the above-mentioned method for preparing two-dimensional boron olefins further includes the following steps: The two-dimensional hydroborene was obtained by holding it at 60~80℃ for 4~8 h and then cleaning it at 300~400℃.

[0025] First, removing most of the deionized water at a lower temperature can prevent the deionized water from carrying away some of the two-dimensional hydroborene product due to boiling. Then, heat treatment at a higher temperature can more thoroughly remove residual cleaning agents and organic solvents with low DN values, thereby obtaining two-dimensional hydroborene with higher purity and higher yield.

[0026] Preferably, the number of cleaning cycles is 3 to 5.

[0027] Preferably, the cleaning is performed at an air pressure of 1×10⁻⁶. -3 ~2×10 -2 The process is carried out in an inert gas atmosphere of Pa.

[0028] More preferably, the flow rate of the inert gas is 200~500 sccm.

[0029] Preferably, the inert gas is at least one of argon, nitrogen, or helium.

[0030] Preferably, the two-dimensional boronene is in sheet form with an average thickness of 1-4 nm and an average maximum diameter of 1-20 μm.

[0031] Preferably, the crystal phase of the two-dimensional boron hydride is C. mmn Phase, C mmn Hydrogenated boronene possesses unique chemical structure and physicochemical properties: its honeycomb network, with hydrogen atoms linked by BHB hydrogen bridges (B:H = 1:1), endows the material surface with abundant active adsorption sites, enabling it to efficiently capture and bind gases and other molecules in the environment. This results in a stronger adsorption capacity for gases and other molecules compared to two-dimensional materials with fewer surface active sites (such as graphene and MoS2). Simultaneously, it exhibits solid electrolyte characteristics and excellent proton conductivity. This crystalline phase can be obtained by ion exchange reaction using a hydrogen-form cation exchange resin and magnesium diboride in a low-DN value organic solvent.

[0032] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of this invention utilizes organic solvents with low DN values ​​to achieve low-cost and environmentally friendly preparation of two-dimensional hydroborenes. The prepared two-dimensional hydroborenes have a yield of over 70%, high purity, and mild synthesis reaction conditions, which is more advantageous for large-scale industrial production. Attached Figure Description

[0033] Figure 1 These are SEM images of the Tyndall effect and products of the resin supernatant obtained after soaking the purified hydrogen-form ion exchange resin in the organic solvent for 0, 36, and 72 hours. (A, B) show the Tyndall effect of the untreated resin soaked in acetone solution and the morphology of the product prepared by directly using the untreated resin; (C, D) show the Tyndall effect of the resin supernatant after 36 hours of purification and the morphology of the sample prepared by reacting with the resin purified for 36 hours; (E, F) show the Tyndall effect of the resin after 72 hours of purification and the morphology of the product prepared by reacting with the resin purified for 72 hours.

[0034] Figure 2 The HRTEM image of the prepared two-dimensional boronene nanosheets and their corresponding selected electron diffraction (SAED) diffraction pattern are shown.

[0035] Figure 3Image A shows optical images of the three products obtained after reacting 50 mL of resin with 30, 20, and 10 mg of magnesium diboride, respectively, and then centrifuging at 11,000 rpm for 10 min. Images B and D are their corresponding high-magnification SEM images.

[0036] Figure 4 The image shows the EDS spectrum of the product obtained after reacting 50 mL of resin with 30 mg of magnesium diboride.

[0037] Figure 5 In the figures, A to D are SEM images of the products obtained after sealing the reaction for 18 h, 36 h, 54 h, and 72 h, respectively.

[0038] Figure 6 XPS spectra of products prepared under sealed reaction times of 18h, 36h, 54h, and 72h.

[0039] Figure 7 In the diagram, A~D are SEM images of the two-dimensional hydroborene products prepared at sealed reaction temperatures of 5℃, 20℃, 35℃, and 50℃, while E and F are their corresponding XPS and XRD spectra. Detailed Implementation

[0040] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0041] I. Experimental Methods Example 1 Preparation of purified hydrogen-form ion exchange resin: Weigh 50 mL of hydrogen-form ion exchange resin and place it into a beaker containing 200 mL of acetone solvent. The resin is magnetically stirred in acetone for 72 h to precipitate small-molecule oligomers, followed by removal of the yellow supernatant. The cleaned resin is then placed in 100 mL of 1 mol / L dilute hydrochloric acid for 12 hours for acidification. The acidified resin is then repeatedly washed with acetone 10 times to remove moisture. S1. Place the cleaned 500 mL glass bottle in a 70℃ electric drying oven for 10 minutes to remove moisture from the inner wall of the bottle. Then, mix the treated resin with 10 mg of magnesium diborate and place the mixture into a glass bottle containing 50 mL of acetone. Next, fill the bottle with argon gas to ensure complete isolation of the reaction system from the outside air, and seal the bottle with plastic wrap. The sealed reaction temperature is 20℃, and the solution is magnetically stirred at 600 rpm for 72 hours. S2. The sample after magnetic stirring was subjected to a first centrifugation treatment at 500 rpm for 10 min. The supernatant was collected, and this process was repeated twice. A second centrifugation treatment was then performed at 11000 rpm for 10 min. The precipitate was collected and redissolved in deionized water, and this process was repeated twice. The collected precipitate was first baked in a vacuum drying oven at 60°C for 2 hours, and then annealed in a tube furnace filled with argon gas to obtain two-dimensional hydroborene. The annealing conditions were: Ar flow rate of 500 sccm and tube pressure of 1 × 10⁻⁶. -2 Pa, annealing temperature is 100℃, annealing time is 4 h.

[0042] Example 2 The experimental method is the same as in Example 1, except that the purified hydrogen ion exchange resin is obtained by soaking the hydrogen ion exchange resin in the organic solvent for 48 hours.

[0043] Example 3 The experimental method is the same as in Example 1, except that the sealing reaction time in step S1 is 54 h.

[0044] Example 4 The experimental method is the same as in Example 1, except that the sealing reaction temperature in step S1 is 5°C.

[0045] Example 5 The experimental method is the same as in Example 1, except that the sealing reaction temperature in step S1 is 35°C.

[0046] Example 6 The experimental method is the same as in Example 1, except that the sealing reaction temperature in step S1 is 50°C.

[0047] Example 7 The experimental method is the same as in Example 1, except that in step S2, only the first centrifugation is performed at a speed of 500 rpm for 10 min. The supernatant is collected and the process is repeated twice.

[0048] Comparative Example 1 The experimental method was the same as in Example 1, except that the acidified resin was not washed with acetone.

[0049] Comparative Example 2 Under nitrogen atmosphere and at room temperature and normal pressure, magnesium diboride powder of the same amount as in Example 1 was added to methanol or acetonitrile solvent, and ion exchange resin was added at the same time. The mixture was stirred and reacted for 3 days. After the reaction was completed, the mixture was cooled to 255 K and allowed to stand for 24 hours. The filtrate was then collected by filtration. The filtrate was placed on a heating plate and dried under nitrogen atmosphere and at 343 K to obtain yellow powdery borobenzene flakes.

[0050] Comparative Example 3 The experimental method is the same as in Example 1, except that in step S1, the organic solvent is replaced with an equal volume of ethanol with a DN value of 19.2.

[0051] Comparative Example 4 The experimental method is the same as in Example 1, except that the purified hydrogen ion exchange resin is obtained by soaking the hydrogen ion exchange resin in the organic solvent for 36 hours.

[0052] II. Test Results Table 1. Test Results of Examples / Comparative Examples

[0053] Table 1 shows the key factors affecting the yield of two-dimensional boronide: (1) The purification time of the hydrogen-type ion exchange resin was 36h, 48h, and 72h, and the yields increased from 47.2% (Comparative Example 4) to 78% (Example 2) to 81% (Example 1). Small molecule oligomers in the resin compete with target ions for adsorption sites, reducing ion exchange efficiency. Insufficient purification time (e.g., 36h) cannot completely remove oligomers, resulting in low yield. After 72h of purification, the Tyndall effect disappeared, indicating that the oligomers had been completely removed, and the yield was significantly improved.

[0054] (2) Solvent DN value According to Comparative Example 3, using ethanol with a DN value of 19.2, the yield of the ethanol system was 0%. Solvents with low DN values ​​exhibit moderate polarity, which is favorable for hydrogen ion intercalation and ion exchange reactions. Solvents with high DN values ​​may interfere with resin ionization or ion transport, hindering the reaction.

[0055] (3) Reaction temperature As the reaction temperature gradually increased—5℃, 20℃, 35℃, and 50℃ (Examples 4, 1, 5, and 6)—the yields were 72%, 81%, 83%, and 84%, respectively. Appropriately increasing the temperature can enhance solvent polarity and surface tension, promoting ion exchange and diffusion. However, if the temperature exceeds this range, the solvent will boil, and a closed reaction system poses a safety hazard.

[0056] (4) Reaction time The reaction time was increased from 54 h (Example 3) to 72 h, and the yield increased from 77% to 81%. The longer reaction time is beneficial for the ion exchange reaction to proceed fully and improve the conversion rate. Too short a time may lead to incomplete reaction and residual unreacted metal borides.

[0057] (5) Centrifugation method Two-stage centrifugation (Example 1) and single-stage low-speed centrifugation (Example 7) are used, with two-stage centrifugation being more effective in separating products from impurities. High-speed centrifugation can collect smaller nanosheets, improving product purity and yield.

[0058] according to Figure 1 The Tyndall effect can indicate whether the resin has completely removed small molecule oligomers. This is because small molecule oligomers in the resin will be released and dispersed in the supernatant. When laser irradiation is used, the Tyndall effect will appear, which proves the presence of small molecule oligomers. The disappearance of the Tyndall effect after 72 hours of resin treatment proves that the small molecule oligomers in the resin have been completely removed. At this time, the resin purification is complete.

[0059] The untreated resin and the resin treated for 36 hours cannot be used because the surface of the hydrogenated boronene in the SEM image of the product is still covered by small molecule oligomer resin (consistent with the untreated one), resulting in a dark black color in the electron microscope image. This indicates that 36 hours is not enough to complete the purification of the resin and cannot completely remove the small molecule oligomers in the resin.

[0060] Figure 3 middle, Figure 3 Image A shows physical images of the products obtained after reacting magnesium diboride with resin using three different ratios. Black represents the color of the magnesium diboride raw material, and yellow represents the color of boronene. From... Figure 3 As shown in Figure A, after 3 days of reaction between 30 mg magnesium diboride and 50 mL of resin, the main product remains black; the precipitate after the reaction of 20 mg magnesium diboride is a mixture of black and yellow; and the precipitate after the reaction of 10 mg magnesium diboride is yellow. Generally, the yellower the precipitate, the higher the content of borane. Therefore, by observing the color of the precipitate after the reaction, it can be determined that 10 mg magnesium diboride and 50 mL of ion exchange resin is the optimal reaction ratio among these three. From the SEM image (… Figure 3 As shown in BD), when the same 50 mL ion exchange resin is kept constant, the sample obtained by using 30 mg magnesium diboride has a particle structure with a main morphology similar to that of magnesium diboride; the sample obtained by using 20 mg magnesium diboride contains both particle and lamellar structures, with the ratio of particles to lamellars being approximately 2 / 3; and the sample obtained by using 5 mg magnesium diboride is entirely lamellar.

[0061] The purity of two-dimensional boron hydride can be obtained from XPS images. If the characteristic peak of Mg is absent or not obvious, the purity of the two-dimensional boron hydride is 100%. In addition, if the purity of the prepared two-dimensional boron hydride is insufficient and there are doped oxidation products, they will be automatically separated.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing two-dimensional hydroborene, characterized in that, Includes the following steps: S1. Disperse the metal boride and the purified hydrogen-form ion exchange resin in an organic solvent, fill the container with inert gas, stir, and carry out a sealed reaction. S2. Centrifugation process yields the two-dimensional hydroborene; Wherein, the DN value of the organic solvent in step S1 is less than 19; The purified hydrogen-form ion exchange resin was obtained by soaking the hydrogen-form ion exchange resin in the organic solvent for 48-72 hours.

2. The method according to claim 1, characterized in that, In step S1, the ratio of the added metal boride, the purified hydrogen-form ion exchange resin, and the organic solvent is 0.5~2 mg: 5 mL: 5 mL.

3. The method according to claim 1, characterized in that, The metal boride mentioned in step S1 is at least one of magnesium diboride, aluminum diboride, titanium diboride, or calcium hexaboride.

4. The method according to claim 1, characterized in that, The organic solvent mentioned in step S1 is at least one of acetone, acetonitrile, or methanol.

5. The method according to claim 1, characterized in that, The temperature of the sealing reaction in step S1 is 5~50℃.

6. The method according to claim 1, characterized in that, The temperature of the sealing reaction in step S1 is 20~50℃.

7. The method according to claim 1, characterized in that, The sealing reaction time in step S1 is 54~72h.

8. The method according to claim 1, characterized in that, The stirring speed in step S1 is 300~600 rpm.

9. The method according to claim 1, characterized in that, The centrifugation in step S2 includes two centrifugation processes. The conditions for the first centrifugation process are: a rotation speed of 500~1000 rpm and a time of 10~50 min, and the supernatant is collected. The conditions for the second centrifugation process are: a rotation speed of 10000~12000 rpm and a time of 5~10 min.

10. The method according to claim 1, characterized in that, It also includes the following steps: The two-dimensional hydroborene was obtained by holding it at 60~80℃ for 4~8 h and then cleaning it at 300~400℃.

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