Preparation method of wood-based piezoelectric nano generator capable of being applied to indoor intelligent human motion monitoring
By delectin treatment of wood and synthesizing zinc oxide and carbon dot composite materials, the problem of poor output performance of wood-based piezoelectric nanogenerators is solved, and efficient indoor intelligent human motion monitoring and intelligent Internet of Things applications are achieved.
Patent Information
- Application Number
- CN202510626109.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-15
- Publication Date
- 2025-07-11
AI Technical Summary
The existing wood-based piezoelectric nanogenerators have poor output performance and insufficient mechanical properties of natural wood, so they cannot be used in the field of indoor intelligent human motion monitoring.
By delectining the wood and synthesizing zinc oxide and carbon dot composites on the wood cell walls, the morphology of zinc oxide is regulated during hydrothermal synthesis, so that it grows vertically along a specific crystal surface, forming a rod-like structure, and enhancing the piezoelectricity of the wood.
It significantly improves the piezoelectric output performance and mechanical properties of wood-based piezoelectric nanogenerators, can monitor different action signals, and realize indoor intelligent human motion monitoring and intelligent Internet of Things human-computer interaction.
Smart Images
Figure CN120301249A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a preparation method of a wood-based piezoelectric nanogenerator. Background Art
[0002] The preparation of piezoelectric nanogenerators is based on the piezoelectric effect, which means that a potential difference is generated when a material is subjected to external mechanical vibration. Piezoelectric materials are widely used in sensors, actuators, and energy harvesting devices. Piezoelectric nanogenerators can convert mechanical energy into electrical energy, thereby realizing the reuse of waste energy. However, traditional piezoelectric nanogenerators often use lead zirconate titanate with a perovskite structure and wurtzite structure materials such as gallium nitride. These materials are difficult to recycle and non-degradable, and are not suitable for large-scale applications.
[0003] Wood, as one of the most abundant natural biomaterials on earth, has the characteristics of sustainability, renewability, good environmental properties, and biodegradability, and has received extensive attention from researchers in recent years. However, the piezoelectric effect of natural wood is weak, and the piezoelectric constant is 0.4 pC / N, which limits its application as a piezoelectric material in piezoelectric nanogenerators.
[0004] At present, there have been many studies on using wood as a piezoelectric material for piezoelectric nanogenerators. By modifying the wood through chemical treatment and other methods, there are still problems with the poor output performance of wood-based piezoelectric nanogenerators. And in the field of indoor intelligent human motion monitoring, sensors need to have high sensitivity, dynamic response ability, and long-term environmental stability to accurately capture the subtle changes in human motion (such as gait, posture, etc.). Due to insufficient mechanical properties and poor compression resilience of natural wood, it cannot be applied to the field of indoor intelligent human motion monitoring. Summary of the Invention
[0005] The present invention aims to solve the problems of poor output performance of existing wood-based piezoelectric nanogenerators, and insufficient mechanical properties and poor compression resilience of natural wood, which prevent it from being applied to the field of indoor intelligent human motion monitoring. Furthermore, a preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring is provided.
[0006] A preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring is carried out according to the following steps:
[0007] I. Preparation of wood sponge:
[0008] The wood is subjected to delignification treatment to obtain wood sponge;
[0009] II. Preparation of piezoelectric wood:
[0010] ① Immerse the wood sponge in the zinc oxide precursor solution for 5 min to 10 min, then dry it, and repeat the immersion and drying 5 to 10 times to obtain a wood sponge coated with the zinc oxide precursor.
[0011] ② Mix lignin carbon dots, zinc nitrate hexahydrate, hexamethylenetetramine and distilled water to obtain a carbon dot solution. Immerse the wood sponge coated with the zinc oxide precursor in the carbon dot solution and react at a temperature of 90 °C to 110 °C for 1 h to 5 h. Finally, take it out and freeze-dry to obtain piezoelectric wood.
[0012] III. Assembly of the wood-based piezoelectric nanogenerator:
[0013] Assemble the two sides of the piezoelectric wood with the electrode material, then connect the electrode material with the wire, and finally seal it to obtain the wood-based piezoelectric nanogenerator.
[0014] The beneficial effects of the present invention are as follows:
[0015] 1. The piezoelectric output performance of natural wood is poor and it cannot be directly used as a piezoelectric material. By delignifying the wood and synthesizing a zinc oxide and carbon dot composite material on the wood cell wall in the present invention, its piezoelectric output performance is significantly enhanced, and thus it can be used as a piezoelectric material.
[0016] 2. In the present invention, during the hydrothermal synthesis process of carbon dots, the morphology of zinc oxide is regulated. The addition of carbon dots makes zinc oxide grow vertically along the (002) crystal plane during synthesis, forming more rod-like structures (with a diameter of 0.1 μm to 0.3 μm and a length of 0.6 μm to 1 μm). The addition of zinc oxide and carbon dots significantly improves the piezoelectricity of the wood, thereby increasing the output performance of the wood-based piezoelectric nanogenerator.
[0017] 3. In step ② of the second step of the present invention, hydrothermal treatment is adopted to make the microstructure of the wood block looser and the compressibility stronger, which is beneficial to the vibration of the cellulose crystalline region and endows it with good piezoelectricity.
[0018] 4. The wood-based piezoelectric nanogenerator prepared by the present invention has excellent mechanical properties and compression and rebound properties, and its piezoelectric output performance is significantly enhanced. It can monitor different action signals. Combined with deep learning, it can realize an indoor intelligent human motion monitoring system, and thus realize the possibility of human-computer interaction in the intelligent Internet of Things. Description of the Drawings
[0019] Figure 1 It is a structural schematic diagram and working principle diagram of the wood-based piezoelectric nanogenerator prepared in Example 1;
[0020] Figure 2 It is a TEM image of the piezoelectric wood prepared in step ② of Example 1;
[0021] Figure 3 SEM comparison diagrams of the piezoelectric wood prepared in Step 2 ② of Example 1 and the piezoelectric wood prepared in Comparative Example 1 without adding carbon dots. a is Comparative Example 1, and b is Example 1;
[0022] Figure 4 Compression and rebound performance test of the piezoelectric wood prepared in Step 2 ② of Example 1 under different strain rates;
[0023] Figure 5 Electrical output performance diagrams of the wood-based piezoelectric nanogenerators prepared in Step 3 of Comparative Examples 1 to 3;
[0024] Figure 6 Output performance diagrams of the wood-based piezoelectric nanogenerators prepared in Step 3 of Example 1 and Comparative Examples 4 to 6;
[0025] Figure 7 Test diagram of the wood-based piezoelectric nanogenerator prepared in Step 3 of Example 1 under a pressure of 50 N and a high frequency of 2 Hz with the number of cycles greater than 5000;
[0026] Figure 8 Schematic diagram of the operation of the wood-based piezoelectric nanogenerator prepared in Step 3 of Example 1 when assembled into a floor and recognizing signals. Detailed implementation manners
[0027] Detailed implementation manner 1: A preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring, which is carried out according to the following steps:
[0028] I. Preparation of wood sponge:
[0029] The wood is delignified to obtain wood sponge;
[0030] II. Preparation of piezoelectric wood:
[0031] ① The wood sponge is impregnated in the zinc oxide precursor solution for 5 min to 10 min, and then dried. The impregnation and drying are repeated 5 to 10 times to obtain the wood sponge coated with the zinc oxide precursor;
[0032] ② Lignin carbon dots, zinc nitrate hexahydrate, hexamethylenetetramine and distilled water are mixed to obtain a carbon dot solution. The wood sponge coated with the zinc oxide precursor is impregnated in the carbon dot solution, and reacted at a temperature of 90 °C to 110 °C for 1 h to 5 h. Finally, it is taken out and freeze-dried to obtain piezoelectric wood;
[0033] III. Assembly of the wood-based piezoelectric nanogenerator:
[0034] Assemble the two sides of the piezoelectric wood with electrode materials, then connect the electrode materials to wires, and finally seal the layer to obtain a wood-based piezoelectric nanogenerator.
[0035] The beneficial effects of this embodiment are as follows:
[0036] 1. The piezoelectric output performance of natural wood is poor and it cannot be directly used as a piezoelectric material. In this embodiment, the wood is delignified, and a composite material of zinc oxide and carbon dots is synthesized on the wood cell wall, so that its piezoelectric output performance is significantly enhanced, and thus it can be used as a piezoelectric material.
[0037] 2. In this embodiment, during the hydrothermal synthesis process of carbon dots, the morphology of zinc oxide is regulated. The addition of carbon dots makes zinc oxide grow vertically along the (002) crystal plane during synthesis, forming more rod-like structures (with a diameter of 0.1 μm to 0.3 μm and a length of 0.6 μm to 1 μm). The addition of zinc oxide and carbon dots significantly improves the piezoelectricity of the wood, thereby increasing the output performance of the wood-based piezoelectric nanogenerator.
[0038] 3. In step ② of step two in this embodiment, hydrothermal treatment is adopted to make the microstructure of the wood block looser and the compressibility stronger, which is beneficial to the vibration of the cellulose crystalline region and endows it with good piezoelectricity.
[0039] 4. The wood-based piezoelectric nanogenerator prepared in this embodiment has excellent mechanical properties and compression and rebound properties, and its piezoelectric output performance is significantly enhanced. It can monitor different motion signals. Combined with deep learning, it can realize an indoor intelligent human motion monitoring system, and thus realize the possibility of human-computer interaction in the intelligent Internet of Things.
[0040] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the delignification treatment described in step one is specifically carried out according to the following steps: Prepare a KOH solution with a mass percentage of 1% to 3% to obtain impregnation solution 1; Prepare an aqueous solution of NaClO2 with a mass percentage of 1% to 3%, and add glacial acetic acid to adjust the pH of the solution to 4 to 6 to obtain impregnation solution 2; Immerse the wood in impregnation solution 1, keep it at a temperature of 70°C to 90°C for 4 h to 8 h, then take it out and immerse it in impregnation solution 2, keep it at a temperature of 80°C to 100°C until the wood turns white, and replace impregnation solution 2 every 6 h to 8 h during the heat preservation process, then take it out and wash it with deionized water, and finally freeze-dry it at a temperature of -50°C to -60°C for 24 h to 48 h. Others are the same as specific embodiment one.
[0041] In this embodiment, two impregnation solutions are used for delignification, which can better remove lignin and hemicellulose in the wood, have good compatibility and are green and environmentally friendly.
[0042] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is that: the wood is pre-treated balsa wood with a thickness of 15 mm to 20 mm, and the pre-treatment is specifically carried out according to the following steps: respectively wash with ethanol and distilled water 2 to 3 times, and then place under the condition of a temperature of 80 °C to 105 °C and dry for 24 h to 48 h. Others are the same as Specific Embodiment 1 or 2.
[0043] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that: the zinc oxide precursor solution described in step 2 ① is specifically prepared according to the following steps: stir and mix a zinc acetate methanol solution with a concentration of 0.3 mol / L to 0.5 mol / L and ethanolamine, and then let it stand for 1 to 2 days to obtain a zinc oxide precursor solution. Others are the same as Specific Embodiment 3.
[0044] Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is that: the volume ratio of the zinc acetate methanol solution with a concentration of 0.3 mol / L to 0.5 mol / L and ethanolamine is 1:(1 to 2). Others are the same as Specific Embodiments 1 to 4.
[0045] Specific Embodiment 6: The difference between this embodiment and one of Specific Embodiments 1 to 5 is that: the lignin carbon dots described in step 2 ② are specifically prepared according to the following steps: add alkaline lignin powder to distilled water, react under the condition of a temperature of 180 °C to 200 °C for 12 h to 16 h, then centrifuge at a rotation speed of 8000 r / min to 10000 r / min for 3 min to 5 min to remove the solid after centrifugation, and then filter using a 0.22 μm to 0.45 μm filter membrane. After filtration, dialyze in a dialysis bag of 1000 da to 3500 da for 24 h to 48 h, and finally freeze-dry at a temperature of -50 °C to -60 °C for 24 h to 48 h to obtain lignin carbon dots. Others are the same as Specific Embodiments 1 to 5.
[0046] Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 1 to 6 is that: the mass ratio of the alkaline lignin powder to the volume of distilled water is 1 g:(25 to 50) mL. Others are the same as Specific Embodiments 1 to 6.
[0047] Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 1 to 7 is that: the mass ratio of the lignin carbon dots to zinc nitrate hexahydrate described in step 2 ② is 1:(40 to 70); the mass ratio of the lignin carbon dots to hexamethylenetetramine described in step 2 ② is 1:(20 to 30); the mass ratio of the lignin carbon dots to the volume of distilled water described in step 2 ② is 1 g:(3000 to 4000) mL. Others are the same as Specific Embodiments 1 to 7.
[0048] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is as follows: in step ②, the drying is specifically carried out at a temperature of 40°C to 60°C for 5 minutes to 10 minutes; in step ②, the freeze-drying is specifically carried out at a temperature of -50°C to -60°C for 48 hours to 72 hours. Others are the same as those in Embodiments 1 to 8.
[0049] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is as follows: in step ③, the electrode material is copper foil; in step ③, the sealing layer material is acrylic board. Others are the same as those in Embodiments 1 to 9.
[0050] The following examples are used to verify the beneficial effects of the present invention:
[0051] Example 1:
[0052] A preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring is carried out according to the following steps:
[0053] I. Preparation of wood sponge:
[0054] The wood is subjected to delignification treatment to obtain wood sponge;
[0055] II. Preparation of piezoelectric wood:
[0056] ① The wood sponge is impregnated in the zinc oxide precursor solution for 10 minutes, and then dried at a temperature of 60°C for 5 minutes. The impregnation and drying are repeated 5 times to obtain the wood sponge coated with the zinc oxide precursor;
[0057] ② 0.015 g of lignin carbon dots, 0.75 g of zinc nitrate hexahydrate, 0.35 g of hexamethylenetetramine and 50 mL of distilled water are mixed to obtain a carbon dot solution. The wood sponge coated with the zinc oxide precursor is impregnated in the carbon dot solution, reacted at a temperature of 90°C for 3 hours, and finally taken out and freeze-dried at a temperature of -60°C for 48 hours to obtain piezoelectric wood;
[0058] III. Assembly of the wood-based piezoelectric nanogenerator:
[0059] The two sides of the piezoelectric wood are assembled with the electrode material, then the electrode material is connected to the wire, and finally sealed to obtain the wood-based piezoelectric nanogenerator.
[0060] The delignification treatment described in Step 1 is specifically carried out according to the following steps: Prepare a KOH solution with a mass percentage of 2% to obtain Impregnating Solution 1; prepare an aqueous solution of NaClO2 with a mass percentage of 2%, and add glacial acetic acid dropwise to adjust the pH of the solution to 4.6 to obtain Impregnating Solution 2; immerse the wood in Impregnating Solution 1, keep it at a temperature of 90 °C for 4 h, then take it out and immerse it in Impregnating Solution 2, keep it at a temperature of 80 °C for 24 h. At this time, the wood turns white, and Impregnating Solution 2 is replaced every 6 h during the heat preservation process. Then take it out and wash it with deionized water. Finally, freeze-dry it at a temperature of -60 °C for 24 h;
[0061] The wood described is pre-treated balsa wood with dimensions of 15 mm × 15 mm × 15 mm (transverse × radial × longitudinal), and the pre-treatment is specifically carried out according to the following steps: Wash it twice with ethanol and distilled water respectively, and then place it at a temperature of 103 °C and dry it for 24 h.
[0062] The zinc oxide precursor solution described in Step 2① is specifically prepared according to the following steps: Stir and mix a methanol solution of zinc acetate with a concentration of 0.38 mol / L and ethanolamine, and then let it stand for 1 day to obtain the zinc oxide precursor solution; the volume ratio of the methanol solution of zinc acetate with a concentration of 0.38 mol / L to ethanolamine is 1:1.
[0063] The lignin carbon dots described in Step 2② are specifically prepared according to the following steps: Add 1 g of alkaline lignin powder to 50 mL of distilled water, react at a temperature of 180 °C for 12 h, then centrifuge at a speed of 10000 r / min for 5 min to remove the solid after centrifugation, and then filter it using a 0.22 μm filter membrane. After filtration, dialyze it in a dialysis bag with a molecular weight cut-off of 1000 Da for 48 h. Finally, freeze-dry it at a temperature of -60 °C for 48 h to obtain lignin carbon dots.
[0064] The electrode material described in Step 3 is copper foil; the sealing layer material described in Step 3 is acrylic board.
[0065] Comparative Example 1: The difference between this comparative example and Example 1 is that the addition of lignin carbon dots in Step 2② is cancelled. Others are the same as Example 1.
[0066] Comparative Example 2: The difference between this comparative example and Example 1 is that the addition of lignin carbon dots in Step 2② is cancelled, and in Step 2②, the reaction is carried out at a temperature of 90 °C for 1 h. Others are the same as Example 1.
[0067] Comparative Example 3: The difference between this comparative example and Example 1 is that the addition of lignin carbon dots in Step 2② is cancelled, and in Step 2②, the reaction is carried out at a temperature of 90 °C for 5 h. Others are the same as Example 1.
[0068] Comparative Example 4: The difference between this comparative example and Example 1 is that: in step ② of step two, the addition amount of lignin carbon dots is changed to 0.005 g. Others are the same as in Example 1.
[0069] Comparative Example 5: The difference between this comparative example and Example 1 is that: in step ② of step two, the addition amount of lignin carbon dots is changed to 0.01 g. Others are the same as in Example 1.
[0070] Comparative Example 6: The difference between this example and Example 1 is that: in step ② of step two, the addition amount of lignin carbon dots is changed to 0.02 g. Others are the same as in Example 1.
[0071] Figure 1 Figure is the structural schematic diagram and working principle diagram of the wood-based piezoelectric nanogenerator prepared in Example 1; it can be seen from the figure that the compressive stress perpendicular to the diameter cross-section of the piezoelectric wood block will cause deformation and generate polarized charges. These charges form an internal electric field, driving the redistribution of charges between the electrodes, thereby generating current. When the stress is released, the electric field dissipates, causing the electrons to flow in the reverse direction and generating an opposite current.
[0072] Figure 2 Figure is the TEM image of the piezoelectric wood prepared in step ② of Example 1; it can be seen from the figure that zinc oxide and carbon dots are successfully synthesized and uniformly dispersed. The lattice fringe of 0.216 nm in the figure belongs to the (100) crystal plane of the carbon dots, and 0.280 nm and 0.261 nm respectively belong to the (100) and (002) crystal planes of zinc oxide.
[0073] Figure 3 Figure is the SEM comparison image of the piezoelectric wood prepared in step ② of Example 1 and the piezoelectric wood prepared in Comparative Example 1 without adding carbon dots. a is Comparative Example 1, and b is Example 1; it can be seen from the figure that after adding carbon dots, zinc oxide changes from a spherical shape stacked layer by layer to a rod-like structure, changing from a granular shape to a rod-like structure with a diameter of 0.1 μm to 0.3 μm and a length of 0.6 μm to 1 μm, which can enhance the piezoelectric performance of the wood.
[0074] Figure 4 Figure is the compression and rebound performance test of the piezoelectric wood prepared in step ② of Example 1 under different strain rates; as the strain rate increases, the material can also achieve good compression and rebound at a strain rate of 80%.
[0075] The electrical output performance of the above-prepared wood-based piezoelectric nanogenerator was tested with a pressure of 50 N and a frequency of 1 Hz. Figure 5 Figure is the electrical output performance diagram of the wood-based piezoelectric nanogenerator prepared in step three of Comparative Examples 1 to 3. Figure 6Output performance diagram of the wood-based piezoelectric nanogenerator prepared in Step 3 of Example 1 and Comparative Examples 4 to 6; the open-circuit voltage of the wood-based piezoelectric nanogenerator prepared in Example 1 reached 4.15 V, and the short-circuit current reached 25.85 nA. After adding carbon dots, the piezoelectric performance output of the overall piezoelectric wood is better than that of the wood simply added with zinc oxide. The carbon dots and zinc oxide nanorods form a heterostructure and are uniformly loaded in the wood cell wall. After being extruded and deformed by external stress, the synergistic effect of the two improves the piezoelectric performance of the wood.
[0076] Figure 7 Test diagram of the wood-based piezoelectric nanogenerator prepared in Step 3 of Example 1 with the number of cycles greater than 5000 times under a pressure of 50 N and a high frequency of 2 Hz; as can be seen from the figure, the wood-based piezoelectric nanogenerator prepared in Example 1 has excellent piezoelectric output and compression-rebound performance. After the number of cycles is greater than 5000 times under a pressure of 50 N and a high frequency of 2 Hz, it still maintains a piezoelectric output of 4 V.
[0077] Figure 8 Schematic diagram of the operation of the wood-based piezoelectric nanogenerator prepared in Step 3 of Example 1 when assembled into a floor and when identifying signals; after embedding the wood-based piezoelectric nanogenerator into the floor-like structure, signals of four motion postures can be accurately identified, and different motion postures correspond to significantly different signals, which is beneficial to intelligent applications in subsequent machine learning.
Claims
1. A preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring, characterized in that It is carried out according to the following steps: I. Preparation of wood sponge: The wood is subjected to delignification treatment to obtain wood sponge; II. Preparation of piezoelectric wood: ① The wood sponge is impregnated in a zinc oxide precursor solution for 5 min to 10 min, and then dried. The impregnation and drying are repeated 5 to 10 times to obtain a wood sponge coated with a zinc oxide precursor; ② Lignin carbon dots, zinc nitrate hexahydrate, hexamethylenetetramine and distilled water are mixed to obtain a carbon dot solution. The wood sponge coated with a zinc oxide precursor is impregnated in the carbon dot solution, and reacted at a temperature of 90 °C to 110 °C for 1 h to 5 h. Finally, it is taken out and freeze-dried to obtain piezoelectric wood; III. Assembly of wood-based piezoelectric nanogenerator: Both sides of the piezoelectric wood are assembled with electrode materials, then the electrode materials are connected to wires, and finally sealed to obtain a wood-based piezoelectric nanogenerator.
2. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that The delignification treatment described in step I is specifically carried out according to the following steps: Prepare a KOH solution with a mass percentage of 1% to 3% to obtain impregnating solution 1; Prepare an aqueous solution of sodium chlorite with a mass percentage of 1% to 3%, and add glacial acetic acid dropwise to adjust the pH of the solution to 4 to 6 to obtain impregnating solution 2; The wood is impregnated in impregnating solution 1, and kept warm at a temperature of 70 °C to 90 °C for 4 h to 8 h, then taken out and impregnated in impregnating solution 2, and kept warm at a temperature of 80 °C to 100 °C until the wood turns white, and impregnating solution 2 is replaced every 6 h to 8 h during the heat preservation process. Then it is taken out and washed with deionized water, and finally freeze-dried at a temperature of -50 °C to -60 °C for 24 h to 48 h.
3. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 2, characterized in that The wood is pre-treated balsa wood with a thickness of 15 mm to 20 mm, and the pre-treatment is specifically carried out according to the following steps: Wash with ethanol and distilled water 2 to 3 times respectively, and then place it at a temperature of 80 °C to 105 °C and dried for 24 h to 48 h.
4. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that The zinc oxide precursor solution described in step II ① is specifically prepared according to the following steps: A zinc acetate methanol solution with a concentration of 0.3 mol / L to 0.5 mol / L is stirred and mixed with ethanolamine, and then left standing for 1 day to 2 days to obtain a zinc oxide precursor solution.
5. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 4, characterized in that The volume ratio of the zinc acetate methanol solution with a concentration of 0.3 mol / L to 0.5 mol / L to ethanolamine is 1:(1 to 2).
6. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that The lignin carbon dots described in step II ② are specifically prepared according to the following steps: Add alkaline lignin powder to distilled water, react at a temperature of 180 °C to 200 °C for 12 h to 16 h, then centrifuge at a rotation speed of 8000 r / min to 10000 r / min for 3 min to 5 min to remove the solid after centrifugation, and then filter with a 0.22 μm to 0.45 μm filter membrane. After filtration, it is dialyzed in a dialysis bag of 1000 da to 3500 da for 24 h to 48 h, and finally freeze-dried at a temperature of -50 °C to -60 °C for 24 h to 48 h to obtain lignin carbon dots.
7. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 6, characterized in that The mass-volume ratio of the described alkaline lignin powder to distilled water is 1 g : (25 - 50) mL.
8. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that In step 2②, the mass ratio of the described lignin carbon dots to zinc nitrate hexahydrate is 1 : (40 - 70); in step 2②, the mass ratio of the described lignin carbon dots to hexamethylenetetramine is 1 : (20 - 30); in step 2②, the mass-volume ratio of the described lignin carbon dots to distilled water is 1 g : (3000 - 4000) mL.
9. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that The drying described in step 2① is specifically carried out at a temperature of 40°C - 60°C for 5 min - 10 min; the freeze-drying described in step 2② is specifically carried out at a temperature of -50°C - -60°C for 48 h - 72 h.
10. The preparation method of a wood-based piezoelectric nanogenerator applicable to indoor intelligent human motion monitoring according to claim 1, characterized in that The electrode material described in step 3 is copper foil; the sealing layer material described in step 3 is acrylic board.