Preparation method and application of polyimide piezoelectric catalytic material

Abstract

The application provides a preparation method and application of a polyimide piezoelectric catalytic material, and relates to the technical field of piezoelectric catalytic materials. The preparation method comprises the following steps: 1) reacting a nitrogen-rich precursor at a certain temperature to obtain melem after cooling; 2) mixing aprotic strong polar solvent and alcohol solvent to obtain a mixed solvent, dissolving aromatic anhydride in the mixed solvent, adding melem, and stirring to obtain a mixed solution; 3) reacting the mixed solution, and washing and drying the product to obtain the polyimide piezoelectric catalytic material. In step 2), a surfactant can be added at the same time as melem. The prepared polyimide piezoelectric catalytic material has a highly ordered crystalline structure, a rod-like morphology and excellent piezoelectric response performance, has good piezoelectric catalytic activity, and can be better applied to the piezoelectric catalytic field, such as piezoelectric catalytic degradation of various pollutants in water, piezoelectric catalytic decomposition of water to produce hydrogen, piezoelectric catalytic reduction of CO2 into carbon-containing fuel, and piezoelectric catalytic production of hydrogen peroxide.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric catalytic materials technology, and more specifically, to a method for preparing and applying a polyimide piezoelectric catalytic material. Background Technology

[0002] Currently, piezoelectric materials used in catalysis research mainly fall into five categories: wurtzite materials, perovskite materials, two-dimensional layered materials, layered bismuth-based materials, and organic piezoelectric materials. Among them, organic piezoelectric materials are receiving increasing attention due to their easily tunable structure, high designability, and lack of metal elements. Currently, polyvinylidene fluoride (PVDF) is the most widely used organic piezoelectric material, but its variety is relatively limited, and its efficiency needs improvement. Therefore, developing more efficient and stable organic piezoelectric semiconductor catalysts has become a major challenge in the field of piezoelectric catalysis.

[0003] Crystalline polyimide (PI) semiconductor materials are widely used in photocatalysis due to their typical DA structure and highly conjugated, tunable, and designable characteristics. Based on these characteristics and their non-centrosymmetric crystal structure, polyimides also have potential applications in piezoelectric catalysis. Therefore, constructing efficient and stable polyimide piezoelectric catalysts has become a problem of considerable interest. Summary of the Invention

[0004] This invention addresses the problems existing in the prior art by providing a method for preparing and applying polyimide piezoelectric catalytic materials. The method is simple to operate and easy to prepare, requiring no complicated operating procedures.

[0005] The first objective of this invention is to provide a method for preparing a polyimide piezoelectric catalytic material, comprising the following steps: 1) Nitrogen-rich precursor reaction, followed by cooling to obtain melem. 2) A mixed solvent is obtained by mixing an aprotic strongly polar solvent with an alcohol solvent. Aromatic anhydrides are dissolved in the mixed solvent, and melamine is added and stirred to obtain a mixed solution. 3) The mixture is reacted, and the product is washed and dried to obtain the final product.

[0006] Preferably, the nitrogen-rich precursor in step 1) is selected from at least one of cyanamide, dicyandiamide, urea and melamine.

[0007] More preferably, the nitrogen-rich precursor in step 1) is melamine.

[0008] Preferably, the reaction temperature in step 1) is 400-450 °C and the reaction time is 4-6 h.

[0009] More preferably, the reaction temperature in step 1) is 425 °C; the reaction time is 4 h.

[0010] Preferably, the aromatic anhydride in step 2) is selected from at least one of pyromellitic dianhydride (PMDA), biphenyl dianhydride (BPDA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA).

[0011] Preferably, in step 2), the molar ratio of aromatic anhydride to melamine is 1:0.6-1.1, and the total mass of aromatic anhydride and melamine accounts for 5-20 wt% of the total mass of the reaction system.

[0012] More preferably, in step 2), the aromatic anhydride is pyromellitic dianhydride (PMDA), and the molar ratio of PMDA to melleramine is 1:1.

[0013] Preferably, the aprotic strongly polar solvent in step 2) is selected from at least one of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and N,N-dimethylacetamide (DMAc).

[0014] More preferably, the aprotic strongly polar solvent in step 2) is N,N-dimethylformamide (DMF).

[0015] Preferably, the alcohol solvent in step 2) is selected from at least one of diols and polyols.

[0016] More preferably, the alcohol solvent in step 2) is ethylene glycol.

[0017] Preferably, in step 2), the volume ratio of the aprotic strongly polar solvent to the alcohol solvent is 1:0.5-2.

[0018] More preferably, in step 2), the volume ratio of the aprotic strongly polar solvent to the alcohol solvent is 1:1.

[0019] Preferably, in step 2), a surfactant is added simultaneously with the addition of the melleramine. The surfactant is selected from at least one of hexadecyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), and sodium dodecylbenzenesulfonate (SDBS). The amount of the surfactant is 3-25 wt% of the total solid raw materials (aromatic anhydride, melleramine, and surfactant).

[0020] More preferably, the surfactant in step 2) is hexadecyltrimethylammonium bromide (CTAB).

[0021] Preferably, the reaction temperature in step 3) is 180-220 °C and the reaction time is 40-60 h.

[0022] More preferably, the reaction temperature in step 3) is 200 °C and the reaction time is 48 h.

[0023] The second objective of this invention is to provide an application of the polyimide piezoelectric catalytic material prepared by the above preparation method in the field of piezoelectric catalysis technology, including piezoelectric catalytic degradation of pollutants in water, piezoelectric catalytic decomposition of water to produce hydrogen, piezoelectric catalytic reduction of CO2 to carbon-containing fuels, or piezoelectric catalytic production of hydrogen peroxide.

[0024] Compared with the prior art, the present invention has the following advantages: (1) The method is simple to operate, the reaction is controllable, and the reaction products are adjustable; (2) The polyimide (PI) piezoelectric catalytic material prepared by the method has a highly ordered crystalline structure and rod-shaped morphology. It exhibits excellent piezoelectric response performance in the piezoelectric catalytic degradation of RhB and has good piezoelectric catalytic activity. Attached Figure Description

[0025] Figure 1 XRD patterns of the materials in Examples 1-2 and Comparative Example 1.

[0026] Figure 2 SEM images of the materials in Examples 1-2 and Comparative Example 1.

[0027] Figure 3 Piezoelectric catalytic degradation of RhB concentration versus time curves of materials in Examples 1-2 and Comparative Example 1. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0029] Unless otherwise specified, all methods described herein are conventional methods. Unless otherwise specified, all materials described herein are available from publicly available commercial sources.

[0030] The performance evaluation method for the PI piezoelectric catalytic materials obtained in the following examples is as follows: The structural evaluation method for PI piezoelectric catalysts was carried out by X-ray diffraction (XRD). The structure of the prepared PI piezoelectric catalysts was analyzed using a Bruker D8 Advance series wide-angle X-ray diffractometer (Germany) with a scanning speed of 5° / min and a scanning range of 10°-50°.

[0031] The microstructure evaluation method of PI piezoelectric catalyst material was carried out by scanning electron microscopy (SEM). The prepared PI piezoelectric catalyst material was tested on a Hitachi S-4800 series scanning electron microscope from Japan.

[0032] Evaluation method of piezoelectric catalytic performance of PI piezoelectric catalyst: The piezoelectric catalytic activity of PI piezoelectric catalyst was characterized by the dye Rhodamine B (RhB) under ultrasonic vibration (40 kHz, 240 W). 20 mg of PI piezoelectric catalyst and 100 mL of RhB were mixed in a three-necked flask, with an RhB concentration of 20 mg / L. The mixture was stirred with a magnetic stirrer for 30 min in the dark to reach adsorption equilibrium. Then, the three-necked flask was fixed in an ultrasonic instrument, and ultrasonic degradation was performed. The entire process was carried out in the dark at approximately 25 °C. 4 mL of the reaction solution was aspirated every 10 minutes, and the catalyst was separated by centrifugation. The concentration of the RhB aqueous solution was then determined using a MAPADA UV-6100 UV-Vis spectrophotometer.

[0033] Example 1 The PI piezoelectric catalytic material prepared by solvothermal method using PMDA and Melem is as follows: 5 g of melamine was weighed and placed in a covered crucible. The crucible was then placed in a muffle furnace at 425 °C. After reacting for 4 h, the mixture was allowed to cool naturally. The resulting sample was Melem. N,N-dimethylformamide (DMF) and ethylene glycol were mixed uniformly at a volume ratio of 1:1 to prepare 10 mL of a mixed solvent. Then, 1.0906 g of pyromellitic dianhydride (PMDA) was weighed and dissolved in the mixed solvent, and stirred until dissolved. Subsequently, 1.0909 g of Melem was added and stirred for 1 h until uniformly mixed. The mixed solution was transferred to a Teflon autoclave and then to a high-temperature oven at 200 °C for 48 h. After allowing the reaction to cool naturally, the resulting product was washed three times with DMF and water, centrifuged, and then dried in a vacuum oven for 12 h to obtain the PI piezoelectric catalyst.

[0034] 20 mg of the prepared PI piezoelectric catalytic material was used in a piezoelectric catalytic RhB degradation experiment. After 30 minutes, the degradation rate of RhB was 63.8%.

[0035] XRD patterns are attached. Figure 1 As shown in Example 1, the sample is a highly ordered crystalline PI; SEM images are attached. Figure 2 As shown in Example 1, the sample has a rod-like morphology; The RhB concentration versus time curve is attached. Figure 3 As shown in Example 1; Specific data are shown in Table 1, Example 1.

[0036] Example 2 The PI piezoelectric catalytic material prepared by a solvothermal method using PMDA and Melem with the assistance of CTAB is as follows: Same as Example 1, except that 0.2 g of CTAB was added along with Melem to assist in the solvothermal synthesis of PI piezoelectric catalyst material.

[0037] 20 mg of the prepared PI piezoelectric catalytic material was used in a piezoelectric catalytic RhB degradation experiment. After 30 minutes, the degradation rate of RhB was 92.1%.

[0038] XRD patterns are attached. Figure 1 As shown in Example 2, the sample is a highly ordered crystalline PI; SEM images are attached. Figure 2 As shown in Example 2, the sample has a rod-like morphology and a larger aspect ratio than that in Example 1; The RhB concentration versus time curve is attached. Figure 3 As shown in Example 2; Specific data are shown in Table 1, Example 2.

[0039] Comparative Example 1 The PI piezoelectric catalytic material prepared by high-temperature thermal polymerization of PMDA and Melem is as follows: Weigh 5 g of melamine and place it in a covered crucible. Place the crucible in a muffle furnace at 425 °C and react for 4 h. Then allow it to cool naturally. The resulting sample is Melem. Grind 1.0906 g of PMDA and 1.0909 g of Melem in a mortar until they are uniformly mixed. Place the mixture in a covered crucible and place it in a muffle furnace at 325 °C. React for 4 h and allow it to cool naturally. Then wash the resulting product three times with acetone and water, respectively. After centrifugation, dry it in a vacuum oven for 12 h to obtain the PI piezoelectric catalyst.

[0040] 20 mg of the prepared PI piezoelectric catalytic material was used in a piezoelectric catalytic RhB degradation experiment. After 30 minutes, the degradation rate of RhB was 33.6%.

[0041] XRD patterns are attached. Figure 1 As shown in Comparative Example 1, the sample is crystalline PI; SEM images are attached. Figure 2 As shown in Comparative Example 1, the sample has a blocky morphology; The RhB concentration versus time curve is attached. Figure 3 As shown in Comparative Example 1; See Table 1 for specific data, Comparative Example 1.

[0042] Table 1 Performance of PI piezoelectric catalytic materials in piezoelectric degradation of RhB

[0043] according to Figure 1 The XRD pattern shows that the polyimide piezoelectric catalytic material prepared by this invention has a highly ordered crystalline structure; according to Figure 2 The SEM images show that the polyimide piezoelectric catalytic material prepared by this invention has a rod-like morphology. The highly ordered crystalline structure, highly conjugated structure, strong polarity due to the large intermolecular dipole moment, and the prepared rod-like morphology all contribute to the excellent piezoelectric catalytic performance of the polyimide piezoelectric catalytic material.

[0044] As can be seen from the data in Table 1, compared with the PI piezoelectric catalyst material prepared by high-temperature thermal polymerization in Comparative Example 1, the PI piezoelectric catalyst materials prepared by solvothermal methods in Examples 1 and 2 exhibit superior piezoelectric response performance and better piezoelectric catalytic activity. Among them, Example 2, synthesized by CTAB-assisted solvothermal method, has even better piezoelectric catalytic performance, achieving a degradation rate of 92.1% for RhB within 30 min.

[0045] Therefore, the PI piezoelectric catalytic material prepared by the solvothermal method proposed in this invention has an ordered crystalline structure and rod-shaped morphology, exhibits excellent piezoelectric catalytic performance, and the preparation process is simple, the reaction is controllable, and the reaction products are adjustable. This implementation scheme has good prospects for industrialization.

[0046] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a polyimide piezoelectric catalytic material, characterized in that, Includes the following steps: 1) Nitrogen-rich precursor reaction, followed by cooling to obtain melamine; 2) A mixed solvent is prepared by mixing an aprotic strongly polar solvent with an alcohol solvent. An aromatic anhydride is dissolved in the mixed solvent, and melamine is added and stirred to obtain a mixed solution. The total mass of the aromatic anhydride and melamine accounts for 5-20 wt% of the total mass of the reaction system. 3) The mixed solution is reacted, and the product is washed and dried to obtain the final product; In step 2), the aromatic anhydride is selected from pyromellitic dianhydride; the volume ratio of the aprotic strongly polar solvent to the alcohol solvent is 1:0.5-2; the molar ratio of the aromatic anhydride to the melamine is 1:0.6-1.1; a surfactant is added simultaneously with the melamine, and the amount of the surfactant is 3-25 wt% of the total mass of the aromatic anhydride, the melamine, and the surfactant; the aprotic strongly polar solvent is selected from N,N-dimethylformamide, the alcohol solvent is selected from ethylene glycol, and the surfactant is selected from hexadecyltrimethylammonium bromide.

2. The preparation method according to claim 1, characterized in that, The nitrogen-rich precursor mentioned in step 1) is selected from at least one of cyanamide, dicyandiamide, urea and melamine.

3. The preparation method according to claim 1, characterized in that, The reaction temperature in step 3) is 180-220℃, and the reaction time is 40-60 h.

4. The preparation method according to claim 3, characterized in that, The reaction temperature in step 3) is 200 °C, and the reaction time is 48 h.

5. The application of a polyimide piezoelectric catalytic material obtained by the preparation method according to any one of claims 1-4 in the field of piezoelectric catalysis technology, characterized in that, The applications include piezoelectric catalysis for degrading pollutants in water, piezoelectric catalysis for decomposing water to produce hydrogen, piezoelectric catalysis for reducing CO2 to carbon-containing fuels, or piezoelectric catalysis for producing hydrogen peroxide.

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