A new piezoelectric sensor made of two-dimensional nanomaterial composite PVDF and its preparation method

Abstract

The present invention provides a novel piezoelectric sensor composed of two-dimensional nanomaterials and PVDF and a preparation method thereof. The piezoelectric material is a piezoelectric material formed by a composite of BiOIO3, BiOIO3 / g-C3N4 two-dimensional nanosheet structure materials and PVDF as an intermediate layer, and metal electrodes are attached to both sides. The piezoelectric material is a two-dimensional nanomaterial / PVDF composite powder prepared by in-situ hydrothermal synthesis or physical mixing, and is formed into nanofibers or nanofilms by electrospinning or spin coating. The present invention hybridizes the two-dimensional nanosheet structure material with PVDF, in-situ hydrothermally regulates the formation of BiOIO3 and its heterojunction interaction with PVDF, introduces the electronic transport properties of g-C3N4, and utilizes the dual two-dimensional components to synergistically modulate the structure and piezoelectric properties of the material. The present invention provides a novel piezoelectric sensor, which has a simple preparation method, is easy to operate, and is suitable for the application of piezoelectric sensing devices in multiple fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic information piezoelectric sensors, and relates to a novel piezoelectric sensor made of two-dimensional nanomaterial composite PVDF and a preparation method thereof. Background Art

[0002] In modern society, piezoelectric materials are widely used in sensors, acoustic and ultrasonic waves, energy harvesting and conversion, precision instruments, and control systems. With the rapid development of the electronics industry, piezoelectric materials are becoming increasingly composite. Research and development of composite forms of polyvinylidene fluoride (PVDF), an important piezoelectric material, can improve its piezoelectric properties and is therefore of great significance for its application in various piezoelectric devices. For example, patent CN201810218379.1 discloses a preparation method of PVDF / graphene flexible piezoelectric material and its flexible piezoelectric generator. The composite material has a higher piezoelectric voltage and a greater energy density; CN202111578098.5 discloses a piezoelectric-triboelectric composite sensor based on a flexible porous PVDF-BTO film, which couples electrostatic induction, piezoelectric effect and porous dipoles to improve the output of the nanogenerator; CN202110794515.3 discloses a multi-level core-shell structure ZnO / PVDF nanofiber flexible piezoelectric sensor. The large amount of deformation caused by the interaction between PVDF and ZnO generates a large amount of piezoelectric potential, thereby improving the piezoelectric output.

[0003] Improving piezoelectric output performance by constructing composite structures and modifying the internal composition and interactions of materials is an effective approach to promoting the application of piezoelectric sensors. Relatively speaking, research on piezoelectric materials composited with PVDF using two-dimensional nanomaterials is relatively limited, particularly those with piezoelectric properties. BiOIO3 exhibits excellent piezoelectric properties, and its two-dimensional nanosheet structure facilitates composite with PVDF, potentially forming a new type of composite piezoelectric material with enhanced piezoelectric performance. Summary of the Invention

[0004] This invention provides a novel piezoelectric sensor made of two-dimensional nanomaterials composited with PVDF and a preparation method. The piezoelectric materials include BiOIO3 / PVDF or BiOIO3 / g-C3N4 / PVDF. This novel piezoelectric sensor utilizes a composite structure of the two-dimensional nanomaterial BiOIO3 and PVDF, and utilizes the semiconductor material g-C3N4 to control the structure and electrical conductivity. Specifically, through in-situ composite construction and optimization, the piezoelectric properties of the composite material are modulated, resulting in a novel piezoelectric sensor.

[0005] The present invention prepares a two-dimensional nanomaterial / PVDF composite powder by in-situ compounding or physical mixing, forms nanofibers or nanofilm piezoelectric materials by electrospinning or spin coating, and assembles them into a piezoelectric sensor, i.e., a new type of piezoelectric sensor composited with two-dimensional nanomaterials and PVDF and its preparation method, using the following technical solutions:

[0006] Preparation of two-dimensional nanomaterial / PVDF composite powder: Method 1, PVDF is dissolved in an organic solvent to form a uniform solution; a certain amount of bismuth precursor metal bismuth salt and iodic acid precursor iodate are uniformly dissolved in deionized water or water / organic solvent, stirred for at least 30 minutes, poured into the PVDF solution in a vigorously stirred state, mixed evenly, and the mixed solution is transferred to a reactor. After a period of hydrothermal reaction, the resulting product is filtered, washed, dried, and ground to obtain BiOIO3 / PVDF composite powder; Method 2, PVDF is dissolved in an organic solvent to form a uniform solution; a certain amount of bismuth precursor metal bismuth salt and iodic acid precursor iodate are uniformly dissolved in deionized water or water / organic solvent, stirred for at least 30 minutes, and then poured into the PVDF solution in a vigorously stirred state. After mixing evenly, the mixed solution is transferred to a reactor. After a period of hydrothermal reaction, the resulting product is filtered, washed, dried, and ground to obtain BiOIO3 / PVDF composite powder. The mixture is added to water or water / organic solvent, stirred for at least 30 minutes, and then poured into a g-C3N4 aqueous dispersion prepared by a conventional calcination method, and stirred for at least 30 minutes. The resulting mixture is added to a vigorously stirred PVDF solution, mixed evenly, and then transferred to a reactor. After a period of hydrothermal reaction, the resulting product is filtered, washed, dried, and ground to obtain a BiOIO3 / g-C3N4 / PVDF composite powder; Method 3: According to the above methods 1 and 2, without adding PVDF, BiOIO3 or BiOIO3 / g-C3N4 powder is prepared, and ground and mixed with PVDF powder to form a composite powder.

[0007] The two-dimensional nanomaterial / PVDF composite piezoelectric material is prepared by electrospinning or spin coating: the two-dimensional nanomaterial / PVDF composite powder is dissolved in an organic solvent, ultrasonically dispersed, and a solution of a certain concentration is prepared; the solution is electrospun to obtain two-dimensional nanomaterial / PVDF composite nanofibers; the solution is spin-coated on a glass slide, dried in a 60°C oven, and peeled off to obtain a two-dimensional nanomaterial / PVDF composite nanofilm.

[0008] Preparation of two-dimensional nanomaterial / PVDF composite piezoelectric sensors: Gather or cut two-dimensional nanomaterial / PVDF composite nanofibers or nanofilms into appropriate sizes, with length and width in the centimeter range, and use this as the middle layer. Aluminum foil or copper foil metal electrodes are pasted on both sides and connected to wires to make a piezoelectric sensor.

[0009] Among them, in the composite piezoelectric material formed by the two-dimensional nanostructured material BiOIO3 or BiOIO3 / g-C3N4 and PVDF, PVDF is the main body, the mass content of BiOIO3 is 0.5-50%, and the mass content of g-C3N4 is 0-30%.

[0010] The bismuth precursor is one of metal bismuth salts such as bismuth nitrate, bismuth chloride, bismuth sulfate, and bismuth citrate, and the iodic acid precursor is one of iodate salts such as potassium iodate and sodium iodate.

[0011] The PVDF is either pure PVDF or modified PVDF.

[0012] The organic solvent used is a common solvent for PVDF, such as one or two of dimethylformamide (DMF), dimethylacetamide (DMAC), and N-methylpyrrolidone (NMP).

[0013] The hydrothermal reaction temperature is 100-200° C., and the hydrothermal reaction time is 4-20 hours.

[0014] In the two-dimensional nanomaterial / PVDF composite powder, BiOIO3 is one or more of a nanosheet layer structure and a nanosheet flower structure formed by aggregation of nanosheets, and g-C3N4 is a nanosheet layer structure.

[0015] The concentration of the two-dimensional nanomaterial / PVDF composite powder dissolved in an organic solvent to form a solution is 5-60wt%.

[0016] Pasting aluminum foil or copper foil metal electrodes on both sides refers to either directly pasting metal electrodes on both sides or coating conductive glue on both sides and then pasting metal electrodes.

[0017] Compared with existing materials and technologies, the present invention has the following beneficial effects.

[0018] The present invention provides a novel piezoelectric sensor composed of two-dimensional nanomaterials and PVDF, and its preparation method. The method involves in-situ synthesis of BiOIO3 on PVDF to form a composite piezoelectric material. Hydrothermal synthesis conditions are then adjusted to control the formation of the BiOIO3 two-dimensional structure and its interaction with PVDF. Furthermore, a g-C3N4 two-dimensional structure is introduced to synergistically modulate the material's structure and piezoelectric properties. By hybridizing a two-dimensional nanosheet structure with PVDF to form a heterogeneous structure, the piezoelectric properties of the composite material are modulated. The piezoelectric performance of the composite material is superior to that of a pure single material. The provided piezoelectric sensor preparation method is simple and easy to operate, making it suitable for application in piezoelectric sensing devices across multiple fields. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the examples, but the present invention is not limited to the following examples.

[0020] Example 1

[0021] 1.0 g of pure PVDF was dissolved in 9.0 g of dimethylformamide (DMF) to form a uniform solution; 0.48 g of bismuth nitrate and 0.65 g of potassium iodate were dissolved in deionized water, stirred for 30 minutes, and then poured into the vigorously stirred PVDF solution. After mixing evenly, the mixture was transferred to a reactor and subjected to a hydrothermal reaction at 160°C for 6 hours. The reaction product was taken out, filtered, washed with water, dried in an oven at 60°C, and ground to obtain BiOIO3 / PVDF composite powder.

[0022] The prepared BiOIO3 / PVDF composite powder was dissolved in DMF and ultrasonically dispersed to prepare a 30wt% solution; the solution was electrospun at a voltage of 15kV, an electrospinning time of 10min, and a receiving distance of 10cm to obtain two-dimensional nanomaterial / PVDF composite nanofibers.

[0023] The prepared two-dimensional nanomaterial / PVDF composite nanofibers were aggregated and arranged into a size of 3×3 cm and used as the middle layer. Aluminum foil metal electrodes were pasted on both sides and connected to the wires to make a piezoelectric sensor.

[0024] Example 2

[0025] 1.0 g PVDF was dissolved in 9.0 g DMF to form a uniform solution; 0.48 g bismuth nitrate and 0.65 g potassium iodate were dissolved in deionized water, stirred for 30 min, and then poured into 0.1 g of g-C3N4 aqueous dispersion prepared by conventional calcination method, stirred for 30 min, and the resulting mixture was added to the vigorously stirred PVDF solution. After mixing evenly, the mixture was transferred to a reactor and subjected to hydrothermal reaction at 140 ° C for 6 h. The reaction product was taken out, filtered, washed, dried in an oven at 60 ° C, and ground to obtain BiOIO3 / g-C3N4 / PVDF composite powder.

[0026] The prepared BiOIO3 / g-C3N4 / PVDF composite powder was dissolved in DMF and ultrasonically dispersed to prepare a 40wt% solution; the solution was electrospun to obtain two-dimensional nanomaterial BiOIO3 / g-C3N4 / PVDF composite nanofibers.

[0027] The prepared BiOIO3 / g-C3N4 / PVDF composite nanofibers were arranged into 3×3 cm and used as the middle layer. Aluminum foil metal electrodes were pasted on both sides and connected with wires to make a piezoelectric sensor.

[0028] Example 3

[0029] 0.48g of bismuth nitrate and 0.65g of potassium iodate were evenly dissolved in water, stirred for 30 minutes, poured into the g-C3N4 aqueous dispersion, stirred for 30 minutes, and after mixing evenly, the mixture was transferred to a reactor and subjected to a hydrothermal reaction at 150°C for 4 hours. The reaction product was taken out, filtered, washed with water, dried in an oven at 60°C, and ground to obtain BiOIO3 / g-C3N4 composite powder, which was ground and mixed with PVDF powder to form a composite powder.

[0030] The prepared two-dimensional nanomaterial / PVDF composite powder was dissolved in DMF and ultrasonically dispersed to prepare a 40wt% solution; the solution was dropped onto a glass sheet using a drop coating method, dried in a 60°C oven, and peeled off to obtain a two-dimensional nanomaterial / PVDF composite nanofilm.

[0031] The prepared two-dimensional nanomaterial / PVDF composite nanofilm was cut into a size of 3×3 cm and used as the middle layer. Conductive glue was coated on both sides of it, and then aluminum foil metal electrodes were pasted on it and connected to the wires to make a piezoelectric sensor.

Claims

1. A novel piezoelectric sensor made of two-dimensional nanomaterial composite PVDF and its preparation method, characterized in that: A novel two-dimensional nanomaterial composite PVDF piezoelectric sensor is composed of a two-dimensional nanomaterial / PVDF piezoelectric material and a metal electrode. That is, the two-dimensional nanomaterial / PVDF piezoelectric material is constructed by combining a two-dimensional nanostructured material with PVDF. The two-dimensional nanostructured material is BiOIO3 and / or BiOIO3 / g-C3N4. The preparation method includes the following steps: Step 1: Preparation of two-dimensional nanomaterial / PVDF composite powder: The preparation methods include three: Method 1, PVDF is dissolved in an organic solvent to form a uniform solution; a certain amount of bismuth precursor metal bismuth salt and iodic acid precursor iodate are uniformly dissolved in deionized water or water / organic solvent, stirred for at least 30 minutes, poured into the PVDF solution in a vigorously stirred state, mixed evenly, and the mixed solution is transferred to a reactor, and a hydrothermal reaction is carried out at a certain temperature. After a period of time, the reaction product is taken out, filtered, washed with water, dried in a 60°C oven, and ground to obtain BiOIO3 / PVDF composite powder; Method 2, PVDF is dissolved in an organic solvent to form a uniform solution; a certain amount of bismuth precursor metal bismuth salt and iodic acid precursor iodate are uniformly dissolved in deionized water or water / organic solvent. The mixture was added into an organic solvent, stirred for at least 30 minutes, and then poured into a g-C3N4 aqueous dispersion prepared by a conventional calcination method, and stirred for at least 30 minutes. The resulting mixture was added to a vigorously stirred PVDF solution, mixed evenly, and then transferred to a reactor for hydrothermal reaction at a certain temperature. After a period of time, the reaction product was taken out, filtered, washed with water, dried in an oven at 60°C, and ground to obtain BiOIO3 / g-C3N4 / PVDF composite powder; Method 3: According to the above methods 1 and 2, without adding PVDF, BiOIO3 or BiOIO3 / g-C3N4 powder was prepared, and ground and mixed with PVDF powder to form a composite powder; Step 2: Forming and preparing two-dimensional nanomaterial / PVDF composite piezoelectric material: The two-dimensional nanomaterial / PVDF composite powder prepared in step 1 is dissolved in an organic solvent and ultrasonically dispersed to form a solution of a certain concentration; the solution is electrospun to obtain two-dimensional nanomaterial / PVDF composite nanofibers; or the solution is dropped onto a glass slide by spin coating, dried in a 60°C oven, and peeled off to obtain a two-dimensional nanomaterial / PVDF composite nanofilm; Step 3: Preparation of two-dimensional nanomaterial / PVDF composite piezoelectric sensor: The two-dimensional nanomaterial / PVDF composite nanofiber or nanofilm prepared in step 2 is aggregated or cut into an appropriate area size, with a length and width of centimeters, and used as the middle layer. Aluminum foil or copper foil metal electrodes are pasted on both sides and connected to the wires to make a piezoelectric sensor.

2. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: In the composite piezoelectric material formed by the two-dimensional nanostructured material BiOIO3 or BiOIO3 / g-C3N4 and PVDF, PVDF is the main component, the mass content of BiOIO3 is 0.5-50%, and the mass content of g-C3N4 is 0-30%.

3. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: The bismuth precursor is one of metal bismuth salts such as bismuth nitrate, bismuth chloride, bismuth sulfate, and bismuth citrate, and the iodic acid precursor is one of iodate salts such as potassium iodate and sodium iodate.

4. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: The PVDF is one of pure PVDF and modified PVDF.

5. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: The organic solvent is a common solvent for PVDF, such as one or two of dimethylformamide (DMF), dimethylacetamide (DMAC), and N-methylpyrrolidone (NMP).

6. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: The hydrothermal reaction temperature in step 1 is 100-200° C., and the hydrothermal reaction time is 4-20 h.

7. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: In the two-dimensional nanomaterial / PVDF composite powder, BiOIO3 is one or more of a nanosheet layer structure and a nanosheet flower structure formed by aggregation of nanosheets, and g-C3N4 is a nanosheet layer structure.

8. A two-dimensional nanomaterial composite PVDF novel piezoelectric sensor and preparation method according to claim 1, characterized in that: The concentration of the two-dimensional nanomaterial / PVDF composite powder dissolved in an organic solvent to form a solution in step 2 is 5 to 60 wt%.

9. A novel piezoelectric sensor made of two-dimensional nanomaterial composite PVDF and a preparation method thereof according to claim 1, characterized in that: The step 3 of pasting aluminum foil or copper foil metal electrodes on both sides refers to directly pasting metal electrodes on both sides or pasting metal electrodes after coating conductive glue on both sides.