MOF@g-C3N4 nanoparticle electrorheological fluid and its preparation method

Abstract

The application relates to an electrorheological fluid of MOF@g-C3N4 hybrid particles and a preparation method thereof. The electrorheological fluid has a dispersed phase and a continuous phase; the dispersed phase is mainly MOF@g-C3N4 nano particles with a spherical porous hybrid lamellar structure prepared by combining a calcination method and a solvothermal method.

Description

Technical Field

[0001] This application belongs to the field of electrical materials, specifically relating to a MOF@g-C3N4 nanoparticle electrorheological fluid and its preparation method. Background Technology

[0002] Electrorheological fluids (ER fluids), as smart materials, are suspension systems composed of dielectric microparticles and their composites dispersed in an insulating liquid. This system can undergo a solid-liquid transition under the presence of an electric field; this transition is rapid and reversible. This means that the rheological properties of ER fluids change with the applied electric field. When an electric field is applied, the solid particles in the ER fluid will form chain-like or columnar structures along the direction of the electric field, causing the ER fluid to change from a liquid to a solid state. In this case, its rheological properties are greatly improved. Simultaneously, its highly ordered structure and ultra-high specific surface area make it a promising candidate for applications in clutches, dampers, and actuators.

[0003] Chinese patent application CN113755229A discloses a C3N4 / TiO2 nanocomposite electrorheological fluid and its preparation method. The dispersed phase of the electrorheological fluid is C3N4 / TiO2 nanocomposite particles, which are prepared by a two-step method. The obtained C3N4 has the characteristics of a loose and porous two-dimensional material. After loading TiO2 nanoparticles, a C3N4 / TiO2 nanocomposite particle is formed. Summary of the Invention

[0004] The purpose of this application is to provide an electrorheological fluid containing MOF@g-C3N4 nanoparticles and its preparation method.

[0005] The MOF@g-C3N4 nanoparticle electrorheological fluid provided in the first aspect of this application has a dispersed phase and a continuous phase; the dispersed phase is a spherical porous hybrid lamellar structure of MOF@g-C3N4 nanoparticles; the continuous phase is dimethyl silicone oil. The MOF@g-C3N4 nanoparticles are nanoparticles formed by the hybridization of MOF and g-C3N4.

[0006] The dispersed phase is prepared by calcination and solvothermal methods, and the weight ratio of the dispersed phase to the continuous phase is 1:10.

[0007] The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid provided in the second aspect of this application involves first synthesizing carbon nitride particles by calcination, and then synthesizing MOF@g-C3N4 nanoparticles by solvothermal method; it can prepare the MOF@g-C3N4 nanoparticle electrorheological fluid described in any of the preceding embodiments.

[0008] In some embodiments of this application, the preparation method more specifically includes:

[0009] Preparation of carbon nitride (g-C3N4): Sodium nitrate and melamine are reacted at high temperature to remove impurities, and then carbon nitride is obtained.

[0010] Preparation of the suspension: Dimethylformamide (DMF) and anhydrous methanol were mixed to obtain a first mixed solution; terephthalic acid (BDC), hexadecyltrimethylammonium bromide (CTAB) and carbon nitride were added to the first mixed solution and stirred at room temperature until completely dissolved to obtain a second mixed solution; acetic acid was added to the second mixed solution and stirred, then tetrabutyl titanate (TBT) was added, and after continuous stirring, the mixture was placed in a reaction vessel for solvothermal synthesis to obtain the suspension;

[0011] Preparation of the dispersed phase: The suspension obtained from the reaction was washed and impurities were removed, and then dried to obtain MOF@g-C3N4 nanoparticles as the dispersed phase.

[0012] Obtaining electrorheological fluid: The dispersed phase and dimethyl silicone oil as the continuous phase are prepared to form an electrorheological fluid.

[0013] In some embodiments of this application, in the table of steps for preparing carbon nitride, the molar ratio of sodium nitrate to melamine is 1:15, and the high-temperature reaction temperature is 500-550℃.

[0014] In some embodiments of this application, the carbon nitride preparation steps are as follows: sodium nitrate and melamine are uniformly mixed and heated in a muffle furnace to about 500°C for 2 hours, then the temperature is increased to about 550°C at a heating rate of 10°C / h and heated for 2 hours; the resulting product is centrifuged with anhydrous methanol and anhydrous ethanol to remove impurities, and then dried to obtain carbon nitride.

[0015] In some embodiments of this application, in the preparation step of the suspension, the weight ratio of DMF to anhydrous methanol is 1:1.3. The weight ratio of BDC, CTAB, and carbon nitride is 87.5:1.75:1, and the weight ratio of the three to the first mixed solution is 1:30.

[0016] The weight ratio of acetic acid to the second mixed solution is 1:40; the weight ratio of TBT to the second mixed solution is 1:72.

[0017] The stirring time is 30 minutes. The temperature of the solvothermal method is 150°C, and the reaction time is 24 hours.

[0018] In some embodiments of this application, in the preparation step of the dispersed phase, the suspension is first washed with dimethylformamide, and then impurities are removed in a centrifuge using anhydrous methanol and anhydrous ethanol, and the dispersed phase is obtained after drying.

[0019] In some embodiments of this application, washing can be performed at a rotation speed of 7000 r / min; after removing impurities, washing can be performed at a rotation speed of 7500 r / min; and drying can be performed at 75°C for 10 hours.

[0020] In some embodiments of this application, the weight ratio of the dispersed phase to the continuous phase is 1:10 in the step of obtaining the electrorheological fluid.

[0021] Compared with the prior art, this application has the following advantages:

[0022] The preparation method provided in at least one embodiment of this application involves calcination and solvothermal methods, and MOF@g-C3N4 nanoparticles are prepared in two steps; the manufacturing process is simple and does not require special experimental instruments; the obtained product is a spherical porous hybrid lamellar structure with a regular spatial structure.

[0023] The electrorheological fluid formulated with MOF@g-C3N4 nanoparticles and dimethyl silicone oil according to at least one embodiment of this application exhibits high mechanical properties, excellent electrorheological efficiency, and good anti-settling properties. Due to its large specific surface area and high dielectric constant, the nanoparticles possess rapid electric field response speed and excellent electrorheological performance, making this material a high-performance electrorheological material. Attached Figure Description

[0024] Figure 1 XRD pattern of carbon nitride prepared by calcination;

[0025] Figure 2 FT-IR spectrum of carbon nitride prepared by calcination;

[0026] Figure 3 The image shows a transmission electron microscope (TEM) image of the electrorheological fluid obtained in Example 1.

[0027] Figure 4 The FT-IR spectrum of the electrorheological fluid obtained in Example 1;

[0028] Figure 5 The graph shows the relationship between shear strength and shear rate of the electrorheological fluid obtained in Example 1.

[0029] Figure 6 The image shows a transmission electron microscope (TEM) image of the electrorheological fluid obtained in Example 2.

[0030] Figure 7 The graph shows the relationship between shear strength and shear rate of the electrorheological fluid obtained in Example 2.

[0031] Figure 8 Here is a scanning electron microscope image of the electrorheological fluid obtained in Example 3;

[0032] Figure 9a and Figure 9bThe image shows a transmission electron microscope (TEM) image of the electrorheological fluid obtained in Example 3.

[0033] Figure 10 The graph shows the relationship between shear strength and shear rate of the electrorheological fluid obtained in Example 3. Detailed Implementation

[0034] The technical solution of this application will be described in detail below with reference to specific embodiments. However, it should be understood that, without further description, the structure and features of one embodiment can be beneficially combined with other embodiments.

[0035] The metal-organic framework (MOF) mentioned in this application is a type of ultraporous nanomaterial with extremely wide applications. Carbon nitride (g-C3N4) is a polymer semiconductor in which CN atoms are arranged in an sp... 2 Hybridization forms a highly delocalized π-conjugated system.

[0036] The first embodiment of this application provides a MOF@g-C3N4 nanoparticle electrorheological fluid (hereinafter referred to as electrorheological fluid), which is a nanoparticle type electrorheological fluid that is a hybrid of MOF and g-C3N4; the dispersed phase of the electrorheological fluid is spherical porous hybrid layered MOF@g-C3N4 nanoparticles, and the continuous phase is dimethyl silicone oil.

[0037] The spherical porous hybrid sheet structure refers to the spherical porous structure formed by the hybrid stacking of MOF and g-C3N4, as well as the sheet structure of g-C3N4 itself.

[0038] The dispersed phase was prepared by calcination and solvothermal methods; it has a unique morphology, consisting of a spherical porous hybrid lamellar structure. The electrorheological fluid formulated using dimethyl silicone oil as the continuous phase exhibits good anti-settling properties, low density, and an electrorheological efficiency of 991, demonstrating a very strong electrorheological effect.

[0039] The second embodiment of this application provides a method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid, comprising the following steps:

[0040] (1) Preparation of carbon nitride (g-C3N4):

[0041] Sodium nitrate and melamine are reacted at high temperature to remove impurities, yielding carbon nitride. The molar ratio of sodium nitrate to melamine is 1:15, and the reaction temperature is 500-550℃.

[0042] More specifically, sodium nitrate and melamine are uniformly mixed and heated in a muffle furnace to about 500°C for 2 hours. Then, the temperature is increased to about 550°C at a heating rate of 10°C / h and heated for another 2 hours. The resulting product is centrifuged with anhydrous methanol and anhydrous ethanol to remove impurities and then dried to obtain carbon nitride.

[0043] (2) Preparation of suspension:

[0044] Dimethylformamide (DMF) and anhydrous methanol were mixed to obtain a first mixed solution. Terephthalic acid (BDC), hexadecyltrimethylammonium bromide (CTAB), and carbon nitride were added to the first mixed solution and stirred at room temperature until completely dissolved to obtain a second mixed solution. Acetic acid was added to the second mixed solution, and the mixture was stirred. Then, tetrabutyl titanate (TBT) was added, and after continuous stirring, the mixture was placed in a reaction vessel for solvothermal synthesis to obtain a suspension. The weight ratio of DMF to anhydrous methanol was 1:1.3. The weight ratio of BDC, CTAB, and carbon nitride was 87.5:1.75:1, and the weight ratio of these three to the first mixed solution was 1:30. The weight ratio of acetic acid to the second mixed solution was 1:40; the weight ratio of TBT to the second mixed solution was 1:72. The continuous stirring time was 30 minutes. The solvothermal reaction was carried out at 150°C for 24 hours.

[0045] (3) Preparation of the dispersed phase:

[0046] The resulting suspension was washed to remove impurities and then dried to obtain MOF@g-C3N4 nanoparticles as the dispersed phase.

[0047] More specifically, the suspension can be washed once with dimethylformamide, then impurities can be removed in a centrifuge using anhydrous methanol and anhydrous ethanol, and the dispersed phase can be obtained after drying.

[0048] Washing can be performed at 7000 rpm; impurity removal can be performed at 7500 rpm; drying can be performed at 75°C for 10 hours.

[0049] (4) Obtaining electrorheological fluid:

[0050] A dispersive phase and dimethyl silicone oil, which serves as the continuous phase, are used to prepare an electrorheological fluid. The weight ratio of the dispersive phase to the continuous phase is 1:10.

[0051] The present application will be described in detail below with reference to specific embodiments, but it should not be construed as an absolute limitation of the present application.

[0052] Experimental Example 1 (Preparation of Carbon Nitride)

[0053] 0.28 g of sodium nitrate and 6.24 g of melamine were mixed evenly and transferred to a semi-closed crucible with a lid. The crucible was placed in a muffle furnace and heated to 500 °C and calcined for 2 hours. Then, the temperature was increased to 550 °C at a heating rate of 10 °C / h and calcined for 2 hours. The product was centrifuged five times with anhydrous methanol and anhydrous ethanol to remove impurities. Then, it was placed in a 75 °C oven for 10 hours to obtain carbon nitride (g-C3N4).

[0054] Figure 1 The XRD pattern of the carbon nitride sample shows distinct characteristic peaks at 2θ = 12.8 and 27.5, corresponding to the (002) and (100) crystal planes of carbon nitride. The diffraction peaks are sharp, indicating good crystallinity. Figure 2 As shown, the chemical composition of carbon nitride was identified by FT-IR spectroscopy. For carbon nitride, the characteristic peak appears at 806.92 cm⁻¹. -1 The peak should be the characteristic stretching vibration peak of the 3-S-triazine derivative (N-(C)3 or C-NH-C) of the carbon nitride unit, 1230-1700 cm⁻¹. -1 It should be the hybrid stretching vibration of the CN bond and 3446.98 cm. -1 This is related to the stretching vibration of the NH bond.

[0055] Experimental Example 2 (C3N4 addition amount: 0.15g)

[0056] 65 mL of DMF and 10 mL of anhydrous methanol were added to a 250 mL beaker to obtain a first mixed solution. Then, 3.5 g of BDC, 0.7 g of CTAB, and 0.15 g of carbon nitride were weighed and added to the first mixed solution. The mixture was stirred at room temperature until completely dissolved to obtain a second mixed solution. 3.5 mL of acetic acid was added to the second mixed solution, and the mixture was stirred for 10 minutes. Then, 2 mL of LBT was added to the stirred solution, and the mixture was stirred for 30 minutes. The solution was then placed in a reaction vessel and subjected to a solvothermal reaction at 150 °C for 24 hours to obtain a suspension. The resulting suspension was first washed once with DMF at 7000 rpm, then centrifuged at 7500 rpm using anhydrous methanol and anhydrous ethanol to remove impurities. Finally, the suspension was dried at 75 °C for 10 hours to obtain the MOF@g-C3N4 nanoparticles.

[0057] The dried MOF@g-C3N4 nanoparticles were used as the dispersant, and dimethyl silicone oil was used as the continuous phase. The weight ratio of the dispersed phase to the continuous phase was 1:10 to prepare an electrorheological fluid.

[0058] like Figure 3 As shown in the TEM images, the hybrid nanoparticles possess a regular spatial structure and are clearly loaded with sheet-like carbon nitride on their surface, with all particles being cubic blocks of 200-300 nm in size. Figure 4As shown, the chemical composition of the hybrid particles was identified by FT-IR spectroscopy, and compared with... Figure 2 The characteristic peak of MOF-hybridized nanoparticles is at 3445.19 cm⁻¹. -1 The peak intensity decreased at that point, indicating that there is an interaction between the layers.

[0059] At room temperature, 0.15 g of the dispersed phase sample and 1.5 mL of dimethyl silicone oil were ground evenly in a mortar to obtain an electrorheological fluid, and its electrorheological effect was tested in an electrorheological tester. Figure 5 This is a graph showing the relationship between the shear strength and shear rate of the electrorheological fluid containing the nanoparticles under different electric fields. The electrorheological efficiency is calculated using the formula η = (τ...). E The calculation yields a current-rate efficiency of 701, indicating a good current-rate effect.

[0060] Experimental Example 3 (C3N4 addition amount: 0.25g)

[0061] 65 mL of DMF and 10 mL of anhydrous methanol were added to a 250 mL beaker to obtain a first mixed solution. Then, 3.5 g of BDC, 0.7 g of CTAB, and 0.25 g of carbon nitride were weighed and added to the first mixed solution. The mixture was stirred at room temperature until completely dissolved to obtain a second mixed solution. 3.5 mL of acetic acid was added to the second mixed solution, and the mixture was stirred for 10 minutes. Then, 2 mL of TBT was added to the stirred solution, and the mixture was stirred for 30 minutes. The mixture was then placed in a reaction vessel and subjected to a solvothermal reaction at 150 °C for 24 hours to obtain a suspension. The resulting suspension was first washed once with DMF at 7000 rpm, and then centrifuged at 7500 rpm using anhydrous methanol and anhydrous ethanol to remove impurities. The product was dried at 75 °C for 10 hours to obtain the MOF@g-C3N4 nanoparticles.

[0062] The dried MOF@g-C3N4 nanoparticles were used as the dispersant, and dimethyl silicone oil was used as the continuous phase. The weight ratio of the dispersed phase to the continuous phase was 1:10 to prepare an electrorheological fluid.

[0063] from Figure 6 The transmission electron microscopy (TEM) images show that the MOF surface is etched with a porous structure, which increases the specific surface area and can effectively improve the electrorheological effect. Figure 7 This is a graph showing the relationship between shear strength and shear rate under different electric fields. The electrorheological efficiency is 680.08, indicating excellent electrorheological performance.

[0064] Experimental Example 4 (C3N4 addition amount: 0.4g)

[0065] 65 mL of DMF and 10 mL of anhydrous methanol were added to a 250 mL beaker to obtain a first mixed solution. Then, 3.5 g of BDC, 0.7 g of CTAB, and 0.4 g of carbon nitride were weighed and added to the first mixed solution. The mixture was stirred at room temperature until completely dissolved to obtain a second mixed solution. 3.5 mL of acetic acid was added to the second mixed solution, and the mixture was stirred for 10 minutes. Then, 2 mL of LBT was added to the stirred solution, and the mixture was stirred for 30 minutes. The solution was then placed in a reaction vessel and subjected to a solvothermal reaction at 150 °C for 24 hours to obtain a suspension. The resulting suspension was first washed once with DMF at 7000 rpm, then centrifuged at 7500 rpm using anhydrous methanol and anhydrous ethanol to remove impurities. Finally, the suspension was dried at 75 °C for 10 hours to obtain the MOF@g-C3N4 nanoparticles.

[0066] The dried MOF@g-C3N4 nanoparticles were used as the dispersant, and dimethyl silicone oil was used as the continuous phase. The weight ratio of the dispersed phase to the continuous phase was 1:10 to prepare an electrorheological fluid.

[0067] The scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the prepared electrorheological fluid samples are shown below. Figure 8 As shown in Figure 9; Figure 9a and Figure 9b All images are transmission electron microscopy (TEM) images. Figure 9a This is a transmission electron microscope (TEM) image of a 500-nanometer size at 12000x magnification. Figure 9b The image is a transmission electron microscope image at 10,000x magnification for a 500-nanometer size. It can be seen that numerous MOF particles are loaded on the surface of the sheet carbon nitride. The particle size of the MOF is approximately between 200 and 300 nanometers, and it has a porous structure.

[0068] At room temperature, 0.15 g of the dispersed phase sample and 1.5 mL of dimethyl silicone oil were ground evenly in a mortar to obtain an electrorheological fluid, and its electrorheological effect was tested in an electrorheological tester. Figure 10 This is a graph showing the relationship between shear strength and shear rate of the electrorheological fluid containing these nanoparticles under different electric fields. Without an electric field, the shear strength and shear rate increase linearly, a typical characteristic of Newtonian fluids. Under the influence of an applied electric field, the particles rapidly polarize, with dipoles absorbing each other. As the electric field strength increases, the shear stress also continuously increases, resulting in a plateau region in the high-frequency range, exhibiting characteristics of Bingham fluids. The electrorheological efficiency is calculated using the formula η = (τ...). E The calculation yields a current-rate efficiency of 991, demonstrating excellent current-rate effect.

[0069] Comparative Example

[0070] This application is compared with prior art application CN113755229A (A C3N4 / TiO2 nanocomposite particle electrorheological fluid and its preparation method); the differences between the two are as follows:

[0071] (1) Different preparation methods

[0072] The electrorheological fluid of this application has a dispersed phase of MOF@g-C3N4 nanoparticles with a spherical porous hybrid lamellar structure. Carbon nitride particles are first synthesized by calcination, and then MOF@g-C3N4 nanoparticles are synthesized by solvothermal method.

[0073] The comparative application discloses a C3N4 / TiO2 nanocomposite electrorheological fluid and its preparation method. The dispersed phase of the electrorheological fluid is C3N4 / TiO2 nanocomposite particles. It provides a two-step method for preparing C3N4 / TiO2 nanoparticles, which is an improved two-step composite preparation method. First, a loose and porous two-dimensional material C3N4 is prepared by calcination. Then, using C3N4 as a template, TiO2 nanoparticles are loaded by sol-gel method to form a C3N4 / TiO2 nanocomposite particle.

[0074] (2) Different morphology and structure

[0075] The MOF@g-C3N4 in this application exhibits excellent anti-settling properties, with a sedimentation rate of only 2% after a 30-day sedimentation experiment. This is attributed to the porous structure of MOF@g-C3N4, which enhances its anti-settling performance and enriches its surface polarization. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the prepared samples are shown below. Figure 8 As shown in Figure 9, it can be seen that numerous MOF particles are loaded on the surface of the sheet carbon nitride. The particle size of the MOF is approximately between 200 and 300 nanometers, and it has a porous structure.

[0076] Comparison of scanning electron microscopy and transmission electron microscopy results in the application shows that the C3N4 / TiO2 nanocomposite particles have a porous composite structure, with TiO2 nanoparticles deposited in the interlayer of g-C3N4, uniformly distributed and with small particle size.

[0077] (3) The results are different, especially the indicators representing the electrorheological effect are different.

[0078] In this application Figure 10 This is a graph showing the relationship between shear strength and shear rate of the electrorheological fluid containing these nanoparticles under different electric fields. As the electric field strength increases, the shear stress also increases, resulting in a plateau region in the high-frequency range. This region is characterized by Bingham fluid properties, and the electrorheological efficiency is calculated using the formula η = (τ...). E The calculation yields a current-rate efficiency of 991, demonstrating excellent current-rate effect.

[0079] Comparison of applications Figure 7 This figure shows the relationship between shear strength and shear rate of g-C3N4 / TiO2 nanoparticle-based electrorheological fluid under different electric field strengths. As can be seen from the figure, the voltage is increased to 3 kV, and the current density is relatively low, indicating that the electrorheological fluid of this system has good breakdown resistance. The figure also shows that the shear stress continuously increases with increasing electric field strength, exhibiting a plateau region in the high-frequency region, characterized by Bingham fluid properties. The electrorheological efficiency is 345%, demonstrating a very strong electrorheological effect.

[0080] In this application, MOF@g-C3N4 exhibits excellent anti-settling properties, with a settlement rate of only 2% after a 30-day settlement test. This is because the porous structure on the surface of MOF@g-C3N4 allows dimethyl silicone oil to penetrate into the spheres, thereby improving the anti-settling performance.

[0081] (4) Different composite material compositions

[0082] In this application Figure 1 The XRD pattern of the electrorheological fluid shows distinct characteristic peaks of carbon nitride at 2θ = 12.8 and 27.5, corresponding to the (002) and (100) crystal planes of carbon nitride. The diffraction peaks are sharp, indicating good crystallinity. Its scanning electron microscope (SEM) and transmission electron microscope (TEM) images are shown below. Figure 8 As shown in Figures 9, it can be seen that numerous MOF particles are loaded on the surface of the sheet carbon nitride. The particle size of the MOF is approximately between 200 and 300 nanometers, and it has a porous structure.

[0083] Comparison of applications Figure 2 and Figure 3 The images show SEM and TEM images of g-C3N4 / TiO2 nanoparticles, respectively. The images show that the composite particles have a nanosheet-like morphology, with TiO2 nanoparticles uniformly distributed between the layers. Figure 4 The XRD patterns of g-C3N4 / TiO2 nanoparticles are shown. The XRD pattern of the original TiO2 is matched with that of anatase TiO2 (JCPDS21-1272). By comparing with the standard anatase titanium dioxide card PDF#21-1272, the crystal plane index corresponding to 25.37° is (101), 37.03° is (103), 48.12° is (200), 55.10° is (211), and 62.74° is (204), indicating that the titanium dioxide crystal form is anatase, with sharp peaks and good crystallinity. According to previous studies, g-C3N4 reveals two characteristic information peaks at 2θ=12.8° and 27.4°, corresponding to its (100) and (002) crystal plane indices, respectively. The spectrum of the composite nanoparticles retained the characteristic peaks of both, confirming their coexistence and that the crystal structure remained unchanged.

[0084] This embodiment enhances the electrorheological effect of nanoparticles by modifying them, and prepares various electrorheological composite particles by changing the amount of g-C3N4. The unique structure of layered carbon nitride allows MOFs to adhere more easily to its surface. The porous structure of MOFs improves its anti-settling properties and enriches surface polarization. The large specific surface area of ​​the hybrid nanoparticles enhances the surface activity of the material, thereby increasing the electrorheological effect. Furthermore, the preparation method provided in this application is simple, uses inexpensive raw materials, is safe and harmless, and requires no special experimental equipment.

[0085] The described embodiments are merely preferred embodiments of this application and are not intended to limit the scope of this application. Any modifications and improvements made by those skilled in the art to the technical solutions of this application without departing from the spirit of this application should fall within the protection scope defined by the claims of this application.

Claims

1. A MOF@g-C3N4 nanoparticle electrorheological fluid, characterized in that, It has a dispersed phase and a continuous phase; wherein the dispersed phase is MOF@g-C3N4 nanoparticles with a spherical porous hybrid layered structure, and the continuous phase is dimethyl silicone oil; the MOF@g-C3N4 nanoparticles are nanoparticles formed by the hybridization of MOF and g-C3N4. The preparation method of the MOF@g-C3N4 nanoparticle electrorheological fluid first synthesizes carbon nitride particles by calcination, and then synthesizes MOF@g-C3N4 nanoparticles by solvothermal method; the preparation method specifically includes: Preparation of carbon nitride g-C3N4: Sodium nitrate and melamine were reacted at high temperature to remove impurities, and carbon nitride was obtained. Preparation of the suspension: Dimethylformamide (DMF) and anhydrous methanol were mixed to obtain a first mixed solution; terephthalic acid (BDC), hexadecyltrimethylammonium bromide (CTAB), and carbon nitride were added to the first mixed solution and stirred at room temperature until completely dissolved to obtain a second mixed solution; acetic acid was added to the second mixed solution and stirred, then tetrabutyl titanate (TBT) was added, and after continuous stirring, the mixture was placed in a reaction vessel for solvothermal synthesis to obtain the suspension; Preparation of the dispersed phase: The suspension obtained from the reaction was washed and impurities were removed, and then dried to obtain MOF@g-C3N4 nanoparticles as the dispersed phase. Obtaining electrorheological fluid: The dispersed phase and dimethyl silicone oil as the continuous phase are prepared to form an electrorheological fluid.

2. The MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 1, characterized in that, The dispersed phase is prepared by calcination and solvothermal methods, and the weight ratio of the dispersed phase to the continuous phase is 1:

10.

3. A method for preparing the MOF@g-C3N4 nanoparticle electrorheological fluid according to any one of claims 1-2, characterized in that, The preparation method first synthesizes carbon nitride particles by calcination, and then synthesizes MOF@g-C3N4 nanoparticles by solvothermal method.

4. The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 3, characterized in that, In the preparation step of the carbon nitride g-C3N4, the molar ratio of sodium nitrate to melamine is 1:15, and the high-temperature reaction temperature is 500-550℃.

5. The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 3, characterized in that, In the preparation steps of the carbon nitride g-C3N4, sodium nitrate and melamine are uniformly mixed and heated in a muffle furnace to about 500°C for 2 hours. Then, the temperature is increased to about 550°C at a heating rate of 10°C / h and heated for 2 hours. The resulting product is centrifuged with anhydrous methanol and anhydrous ethanol to remove impurities and then dried to obtain carbon nitride.

6. The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 3, characterized in that, In the preparation steps of the suspension, the weight ratio of DMF to anhydrous methanol is 1:1.3; the weight ratio of BDC, CTAB and carbon nitride is 87.5:1.75:1, and the weight ratio of the three to the first mixed solution is 1:30; the weight ratio of acetic acid to the second mixed solution is 1:40; and the weight ratio of TBT to the second mixed solution is 1:

72.

7. The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 6, characterized in that, The stirring time is 30 minutes; the temperature of the solvothermal method is 150°C, and the reaction time is 24 hours.

8. The method for preparing MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 3, characterized in that, In the preparation step of the dispersed phase, the suspension is first washed with dimethylformamide, and then impurities are removed in a centrifuge using anhydrous methanol and anhydrous ethanol. After drying, the dispersed phase is obtained.

9. The method for preparing the MOF@g-C3N4 nanoparticle electrorheological fluid according to claim 8, characterized in that, Washing was performed at 7000 r / min; after impurity removal, washing was performed at 7500 r / min; drying was performed at 75°C for 12 hours.

Images