Preparation method of ni single-atom supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst, piezoelectric catalyst and application
By encapsulating a barium titanate piezoelectric catalyst with a nitrogen-doped carbon layer supported by Ni single atoms, and combining single-atom catalysis with the piezoelectric effect, the problems of low efficiency and high cost in the treatment of heavy metal complex wastewater are solved, and efficient degradation of Cu-EDTA wastewater and resource recovery are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Hangzhou Gongshu District University of Technology Future Technology Research Institute
- Filing Date
- 2026-03-10
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies are difficult to effectively treat heavy metal complex wastewater, especially Cu-EDTA wastewater. Traditional methods have low removal efficiency and high cost, and cannot recover valuable metal resources. Traditional piezoelectric catalysts have low carrier separation efficiency, low mechanical energy capture rate and few active sites.
A nitrogen-doped carbon layer supported by Ni single atoms is used to encapsulate a barium titanate piezoelectric catalyst. By coupling single-atom catalysis with the piezoelectric effect, highly active isolated metal atoms are precisely anchored to the surface of the piezoelectric material. The piezoelectric material generates a built-in electric field under mechanical stress, and the single atoms are combined as efficient electron traps and reaction sites to optimize charge separation and polarized adsorption of reactant molecules.
It significantly improves the activity, selectivity and energy utilization efficiency of piezoelectric catalysts, achieves efficient degradation of Cu-EDTA wastewater, reduces treatment costs, and enables the recovery of valuable metal resources.
Smart Images
Figure CN122321911A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of piezoelectric catalytic material preparation and heavy metal complex wastewater treatment, and particularly to a method for preparing a Ni-supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst, the piezoelectric catalyst itself, and its applications. Background Technology
[0002] Heavy metal complexed wastewater, especially wastewater containing copper ethylenediaminetetraacetate (Cu-EDTA), is one of the challenges in current industrial wastewater treatment.
[0003] Due to Cu 2+ It has a strong affinity for functional groups such as amino and carboxyl groups, and readily combines with organic ligands in wastewater to form heavy metal complexes such as copper ethylenediaminetetraacetate (Cu-EDTA). These complexes are highly toxic and diffuse rapidly, posing a serious threat to the ecological environment and human health. Mining, metallurgy, and electroplating industries generate and discharge large amounts of Cu-EDTA-containing wastewater, further exacerbating the pressure on environmental pollution control.
[0004] For this type of heavy metal complex wastewater, traditional treatment methods such as ion exchange, adsorption and precipitation are often unable to effectively break the stable metal-organic coordination bonds, resulting in low Cu-EDTA removal efficiency, high treatment costs and failure to achieve effective recovery of valuable metal resources.
[0005] The piezoelectric effect is a physical phenomenon in which deformable piezoelectric materials mediate the conversion of mechanical energy into electrical energy. It can convert low-frequency mechanical vibration energy (such as water flow, sound waves, and ultrasound) that is widely present in the environment into electrical energy, thereby driving redox reactions and degrading pollutants.
[0006] The piezoelectric effect driving the degradation of organic pollutants mainly utilizes vibrational energy to deform piezoelectric materials, generating a piezoelectric potential. The charge on the surface of the piezoelectric material can provide a sufficient potential gradient to drive various electrochemical reactions. Replacing traditional oxidants with piezoelectric catalysis driven by environmental micro-energy is a promising solution. However, traditional piezoelectric catalysts suffer from low carrier separation efficiency, low mechanical energy capture rate, and few active sites, which severely limit their catalytic performance and application effects in practical wastewater treatment.
[0007] Single-atom catalysis achieves near 100% atomic utilization by dispersing each metal atom into an independent active center, exhibiting unique catalytic activity and high selectivity. However, single atoms on piezoelectric supports need to be "anchored" at specific sites to effectively modulate piezoelectric polarization and charge separation. Precisely controlling atomic positions and coordination environments is extremely challenging. Existing methods are cumbersome, require stringent conditions, and are costly. Furthermore, how mechanical stress specifically alters the electronic state of the single-atom active site; how piezoelectric charge is precisely transported to the single-atom site to participate in the reaction; and the charge transfer and dipole moment changes at the interface between the single atom and the piezoelectric support all influence the final performance, and their quantitative relationships need to be established. Summary of the Invention
[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing a nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst supported by a Ni single atom, as well as the technical solution for the piezoelectric catalyst and its application. By coupling single-atom catalysis with the piezoelectric effect, highly active isolated metal atoms are precisely anchored on the surface of the piezoelectric material, creating a synergistic enhancement mechanism for improving piezoelectric catalytic performance, reducing costs, making it suitable for large-scale preparation, and having broad application prospects.
[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0010] A method for preparing a Ni-doped carbon layer-encapsulated barium titanate piezoelectric catalyst supported on a Ni single atom, characterized by comprising the following steps:
[0011] S1. Dissolve tetrabutyl titanate in a mixed solution of ethanol and deionized water, and disperse it evenly by magnetic stirring in an oil bath. Then add ammonia water and continue stirring to disperse, to obtain solution A. Disperse barium hydroxide octahydrate in deionized water, and disperse it evenly by magnetic stirring in an oil bath, to obtain solution B. Mix solution A and solution B to prepare a mixture.
[0012] S2. Transfer the mixture obtained in step S1 to a high-pressure reactor. After the reaction is complete, wash and dry to obtain barium titanate piezoelectric material.
[0013] S3. The barium titanate piezoelectric material obtained in step S2 is dispersed in a tris(hydroxymethyl)aminomethane buffer solution, then dopamine hydrochloride is added, and the reaction is carried out in an oil bath. After the reaction is completed, the material is washed and dried to obtain a nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst.
[0014] S4. Disperse the nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst obtained in step S3 in deionized water, add nickel nitrate hexahydrate, react in an oil bath, wash and dry after the reaction to obtain the precursor of Ni single-atom-supported nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst.
[0015] S5. The precursor obtained in step S4 is spread in a quartz boat and calcined at high temperature under a nitrogen atmosphere. After cooling, a nitrogen-doped carbon layer loaded with Ni single atoms is obtained to encapsulate a barium titanate piezoelectric catalyst.
[0016] This preparation method is simple in procedure. By coupling single-atom catalysis with the piezoelectric effect, highly active isolated metal atoms are precisely anchored on the surface of the piezoelectric material, creating a synergistic enhancement mechanism for improving piezoelectric catalytic performance. On the one hand, the piezoelectric material generates a built-in electric field under ultrasonic or mechanical stress, driving charge separation and inducing piezoelectric potential. However, these charges are prone to recombination. At this time, the loaded single atoms act as efficient electron "trappers" and reaction sites, which can quickly capture and stabilize the charge carriers (such as electrons or holes) generated by piezoelectricity, greatly suppressing charge recombination. On the other hand, the unique electronic structure and extremely high surface energy of the single atoms can not only optimize the polarization adsorption of reaction molecules by the piezoelectric potential, but also act as catalytic "microreactors," significantly reducing the activation energy barrier of target reactions (such as water splitting and pollutant degradation). This efficient conversion of "mechanical energy-electric energy-chemical energy" combined with the precise activation of atomic-level catalytic sites ultimately achieves breakthroughs in piezoelectric catalytic performance in terms of activity, selectivity, and energy utilization efficiency.
[0017] Preferably, in step S1, when preparing solution A, the volume of tetrabutyl titanate added is 5-10 mL, the oil bath temperature is 70-100℃, the volume of ammonia added is 3-8 mL, and the stirring reaction time is 0.5-1 h.
[0018] Preferably, in step S1, when preparing solution B, the mass of barium hydroxide octahydrate is 10-20 g, the oil bath temperature is 70-100 °C, and the stirring reaction time is 0.5-1 h.
[0019] Preferably, the volume of the reaction vessel in step S2 is 50-100 mL, the reaction temperature is 180-200 °C, and the reaction time is 20-24 h.
[0020] Preferably, the washing in steps S2, S3 and S4 uses anhydrous ethanol and ultrapure water, and the washing is performed 3 to 6 times respectively. The drying temperature is 50 to 70°C and the drying time is 3 to 6 hours.
[0021] Preferably, in step S3, the concentration of the tris(hydroxymethyl)aminomethane buffer solution is 10–20 mmol / L, the pH is ≥8.5, the mass of the barium titanate piezoelectric material is 0.5–1 g, the mass of the dopamine hydrochloride is 0.05–0.1 g, the oil bath temperature is 70–100 °C, and the reaction time is 6–12 h.
[0022] Preferably, in step S4, the amount of nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst added is 0.5-1g, dispersed in 20-30mL of deionized water, the mass of nickel nitrate hexahydrate added is 58.2-232.7mg, the oil bath temperature is 70-100℃, and the reaction time is 10-12h.
[0023] Preferably, the high-temperature calcination temperature in step S5 is 600–900°C, the heating rate during the high-temperature calcination process is 2–5°C / min, and the holding time is 1–3 hours.
[0024] A Ni-supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst prepared by the above-described method is described above. The piezoelectric catalyst contains 0.1 to 2 wt% Ni single atoms by mass, based on a total mass percentage of 100%.
[0025] Application of a Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst as described above in the treatment of heavy metal complex wastewater.
[0026] Preferably, the amount of the nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst supported by Ni single atoms added in the treatment of heavy metal complex wastewater is 0.25-2 g / L, and the catalytic process is excited by ultrasound with a power of 40-300 W for a reaction time of 0.5-3 h.
[0027] Preferably, the heavy metal complexed wastewater is wastewater containing Cu-EDTA, the concentration of Cu-EDTA in the wastewater is 0.1 mmol / L, the pH is 2-10, and the amount of barium titanate piezoelectric catalyst wrapped in a Ni single-atom supported nitrogen-doped carbon layer is 1 g / L based on the wastewater volume.
[0028] The present invention, by adopting the above-described technical solution, has the following beneficial effects:
[0029] 1. The single atom loaded in this invention can serve as an efficient electron "trapper" and reaction site, which can quickly capture and stabilize charge carriers (such as electrons or holes) generated by piezoelectricity, and greatly suppress charge recombination.
[0030] 2. The unique electronic structure and extremely high surface energy of the single atom in this invention can not only optimize the polarization adsorption of reaction molecules by the piezoelectric potential, but also serve as a catalytic "microreactor" to significantly reduce the activation energy barrier of target reactions (such as water decomposition and pollutant degradation).
[0031] 3. By combining the efficient conversion of "mechanical energy-electric energy-chemical energy" with the precise activation of atomic-level catalytic sites, multiple breakthroughs in the activity, selectivity and energy utilization efficiency of piezoelectric catalysis are ultimately achieved. Attached Figure Description
[0032] The present invention will be further described below with reference to the accompanying drawings:
[0033] Figure 1 This is a flowchart illustrating the preparation method of a Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst, the piezoelectric catalyst itself, and the preparation method in its application, according to the present invention.
[0034] Figure 2 These are TEM images of the piezoelectric catalysts prepared in Examples 1, 1, and 2 of this invention.
[0035] Figure 3 This is an EDS image of the piezoelectric catalyst prepared in Example 1 of this invention;
[0036] Figure 4 This is a fine X-ray absorption structure diagram of the piezoelectric catalyst prepared in Example 1 of this invention;
[0037] Figure 5 The image shows the XRD pattern of the piezoelectric catalyst prepared in Example 1 of this invention.
[0038] Figure 6 The Raman spectrum of the piezoelectric catalyst prepared in Example 1 of this invention is shown below.
[0039] Figure 7 The piezoelectric catalysts prepared in Examples 1, 1, and 2 of this invention are shown to demonstrate the piezoelectric catalytic removal effect of Cu-EDTA.
[0040] Figure 8 This is a graph showing the effect of the piezoelectric catalyst prepared in Example 1 of this invention being used continuously for 6 times to degrade Cu-EDTA. Detailed Implementation
[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0042] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0044] Example 1
[0045] like Figure 1 The image shows a method for preparing a Ni-doped carbon layer-encapsulated barium titanate (Ni-NC@BTO) piezoelectric catalyst supported on a Ni single atom according to the present invention, comprising the following steps:
[0046] (1) Add 8.5 mL of C 16 H 36 O4Ti was dissolved in 20 mL of a mixture of ethanol and deionized water (volume ratio 1:1), and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C. Then, 4 mL of NH3·H2O was added, and the mixture was stirred and dispersed again to obtain solution A. 11.85 g of Ba(OH)2·8H2O was dispersed in 35 mL of deionized water, and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C to obtain solution B. Solution A and solution B were then mixed to prepare a mixture.
[0047] (2) The mixture was transferred to a 100 mL high-pressure reactor and reacted at 200 °C for 24 h. After the reaction was completed, it was washed three times with anhydrous ethanol and ultrapure water respectively, and dried at 70 °C for 6 h to obtain BaTiO3 piezoelectric material.
[0048] (3) Disperse 1g of the prepared BaTiO3 piezoelectric material in a Tris buffer solution with a concentration of 10mmol / L and pH=8.5, then add 0.1g of dopamine hydrochloride, react in an oil bath at 60℃ for 12h, wash three times with anhydrous ethanol and ultrapure water respectively after the reaction, and dry at 70℃ for 6h to obtain nitrogen-doped carbon layer-coated barium titanate (NC@BTO) piezoelectric catalyst;
[0049] (4) Disperse the prepared 0.5g of NC@BTO piezoelectric catalyst in 20mL of deionized water, then add 116.4mg of Ni(NO3)2·6H2O, react in an oil bath at 60℃ for 12h, wash three times with anhydrous ethanol and ultrapure water respectively after the reaction, and dry at 70℃ for 6h to obtain the precursor of Ni single-atom supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst;
[0050] (5) The prepared precursor was spread in a quartz boat and then calcined at high temperature under a nitrogen atmosphere. The heating rate was 5℃ / min. The temperature was raised to 700℃ and calcined for 2h. After cooling, Ni-NC@BTO piezoelectric catalyst was obtained.
[0051] Comparative Example 1
[0052] Preparation of nitrogen-doped carbon layer-encapsulated barium titanate (NC@BTO) piezoelectric catalyst:
[0053] (1) Add 8.5 mL of C 16 H 36 O4Ti was dissolved in 20 mL of a mixture of ethanol and deionized water (volume ratio 1:1), and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C. Then, 4 mL of NH3·H2O was added, and the mixture was stirred and dispersed again to obtain solution A. 11.85 g of Ba(OH)2·8H2O was dispersed in 35 mL of deionized water, and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C to obtain solution B. Solution A and solution B were then mixed to prepare a mixture.
[0054] (2) The mixture was transferred to a 100 mL high-pressure reactor and reacted at 200 °C for 24 h. After the reaction was completed, it was washed three times with anhydrous ethanol and ultrapure water respectively, and dried at 70 °C for 6 h to obtain BaTiO3 piezoelectric material.
[0055] (3) Disperse 1g of the prepared BaTiO3 piezoelectric material in a Tris buffer solution with a concentration of 10mmol / L and pH=8.5, then add 0.1g of dopamine hydrochloride, react in an oil bath at 60℃ for 12h, wash three times with anhydrous ethanol and ultrapure water respectively after the reaction, and dry at 70℃ for 6h to obtain nitrogen-doped carbon layer-coated barium titanate (NC@BTO) piezoelectric catalyst;
[0056] Comparative Example 2
[0057] Preparation of barium titanate (BaTiO3) piezoelectric catalyst:
[0058] (1) Take 8.5 mL of C 16 H 36 O4Ti was dissolved in 20 mL of a mixture of ethanol and deionized water (volume ratio 1:1), and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C. Then, 4 mL of NH3·H2O was added, and the mixture was stirred and dispersed again to obtain solution A. 11.85 g of Ba(OH)2·8H2O was dispersed in 35 mL of deionized water, and the mixture was magnetically stirred and dispersed evenly in an oil bath at 80 °C to obtain solution B. Solution A and solution B were then mixed to prepare a mixture.
[0059] (2) The mixture was transferred to a 100 mL high-pressure reactor and reacted at 200 °C for 24 h. After the reaction was completed, it was washed three times with anhydrous ethanol and ultrapure water respectively, and dried at 70 °C for 6 h to obtain BaTiO3 piezoelectric catalyst.
[0060] Material characterization comparison
[0061] Characterization of materials prepared in Example 1 and Comparative Examples 1 and 2
[0062] As attached Figure 2 As shown in figure a, the BaTiO3 piezoelectric material exhibits a nanocubic morphology with uniform particle size of approximately 200 nm and a smooth surface free of any impurities. In the NC@BTO piezoelectric material, the cubic morphology is retained, but the surface is now covered with a carbon layer approximately 10 nm thick. Figure 2 (b) indicates that a carbon layer was successfully loaded onto the BTO surface. Additionally, in Figure 2 No significant Ni single-atom loading was observed in Ni-NC@BTO, requiring further characterization and verification. Further EDS analysis was performed on Ni-NC@BTO to determine the elemental distribution (...). Figure 3 As can be seen, the carbon layer was successfully loaded on the outermost layer of the material, and the uniform distribution of Ni elements also confirms the loading of single-atom Ni. The coordination of single-atom Ni still needs to be characterized by X-ray absorption spectroscopy. Figure 4 It can be seen from a that the average valence state of Ni in the Ni-NC@BTO catalyst is between 0 and 2, while Figure 4 b confirms the existence of the Ni-N coordination structure, thus the above results prove the successful loading of single-atom Ni.
[0063] This invention overcomes the problem of requiring specific sites in the preparation of traditional single-atom catalysts by connecting piezoelectric catalysts to single atoms through a carbon layer. By "anchoring" single atoms to the carbon layer, which simultaneously encapsulates the piezoelectric material, this design effectively modulates piezoelectric polarization and charge separation, with the single atom enhancing the piezoelectric polarization. Furthermore, when mechanical stress is applied to the piezoelectric material, piezoelectric charges are transferred through the carbon layer to the single-atom sites, optimizing the charge transport path at the interface and leading to better generation of active substances, thus achieving the goal of pollutant degradation.
[0064] In addition, the three catalysts were characterized by XRD and Raman spectroscopy. Figure 5 As shown, BTO did not exhibit a distinct tetragonal piezoelectric phase structure, while NC@BTO and Ni-NC@BTO showed an amorphous carbon peak at 25.3° diffraction, further confirming the loading of the carbon layer. Further Raman ( Figure 6 Characterized at 308cm -1 The vibrations verified the tetragonal piezoelectric phase structure of BTO. In addition, the appearance of D and G bands proved the loading of carbon layers. The decrease in the proportion indicates that after loading Ni single atoms, the defects in the material increased and the active sites increased, which will be beneficial to the catalytic reaction.
[0065] The method for preparing a Ni-supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst is as follows: The Ni-supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst is prepared by means of a Ni single atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst, wherein the Ni single atom mass percentage content is 0.1 to 2 wt% based on the total mass of the piezoelectric catalyst.
[0066] Experimental Example 1
[0067] Application of the catalysts prepared in Example 1 and Comparative Examples 1 and 2 in the degradation of Cu-EDTA wastewater.
[0068] 100 mg each of the Ni-NC@BTO, NC@BTO, and BTO piezoelectric catalysts prepared in Example 1 and Comparative Examples 1 and 2 were added to 50 mL of 0.1 mmol / L Cu-EDTA solution. After adsorption for 30 min, the piezoelectric catalytic reaction was triggered by ultrasound with a power of 200 W. Samples were taken at regular intervals and filtered through a 0.22 μm polytetrafluoroethylene membrane. The concentration of the target pollutant was determined by high performance liquid chromatography. The maximum reaction time was 3 h. The pH was 3.8. Three replicate groups were set up for each reaction.
[0069] The experimental results are attached. Figure 7 As shown, Figure 7 The results show that NC@BTO and BTO piezoelectric catalysts have limited piezoelectric degradation effects on Cu-EDTA, with degradation rates of 19.3% and 14.1%, respectively. Barium titanate without any modification exhibits limited piezoelectric performance; while the addition of a carbon layer provides some improvement, the effect remains insignificant. Ni-NC@BTO demonstrates a significant piezoelectric degradation effect on Cu-EDTA, achieving approximately 100% degradation within 180 min, which is significantly superior to the piezoelectric catalytic degradation effects of NC@BTO and BTO on Cu-EDTA. Furthermore, Figure 8 It also demonstrated the excellent stability of Ni-NC@BTO, maintaining efficient degradation of Cu-EDTA even after 6 cycles.
[0070] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to achieve substantially the same technical effect are all covered within the protection scope of the present invention.
Claims
1. A method for preparing a Ni monatomic supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst, characterized in that: Includes the following steps: S1. Dissolve tetrabutyl titanate in a mixed solution of ethanol and deionized water, and disperse it evenly by magnetic stirring in an oil bath. Then add ammonia water and continue stirring to disperse, to obtain solution A. Disperse barium hydroxide octahydrate in deionized water, and disperse it evenly by magnetic stirring in an oil bath, to obtain solution B. Mix solution A and solution B to prepare a mixture. S2. Transfer the mixture obtained in step S1 to a high-pressure reactor. After the reaction is complete, wash and dry to obtain barium titanate piezoelectric material. S3. The barium titanate piezoelectric material obtained in step S2 is dispersed in a tris(hydroxymethyl)aminomethane buffer solution, then dopamine hydrochloride is added, and the reaction is carried out in an oil bath. After the reaction is completed, the material is washed and dried to obtain a nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst. S4. Disperse the nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst obtained in step S3 in deionized water, add nickel nitrate hexahydrate, react in an oil bath, wash and dry after the reaction to obtain the precursor of Ni single-atom-supported nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst. S5. The precursor obtained in step S4 is spread in a quartz boat, and the precursor is calcined at high temperature under a nitrogen atmosphere. After cooling, a nitrogen-doped carbon layer loaded with Ni single atoms is obtained to encapsulate a barium titanate piezoelectric catalyst.
2. The preparation method of a Ni monatomic supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst according to claim 1, characterized in that: In step S1, when preparing solution A, the volume of tetrabutyl titanate added is 5-10 mL, the oil bath temperature is 70-100℃, the volume of ammonia water added is 3-8 mL, and the stirring reaction time is 0.5-1 h.
3. The preparation method of a Ni monatomic supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst according to claim 1, characterized in that: In step S1, when preparing solution B, the mass of barium hydroxide octahydrate is 10-20 g, the oil bath temperature is 70-100 °C, and the stirring reaction time is 0.5-1 h.
4. The preparation method of a Ni monatomic supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst according to claim 1, characterized in that: The volume of the reaction vessel in step S2 is 50-100 mL, the reaction temperature is 180-200 °C, and the reaction time is 20-24 h.
5. The method for preparing a Ni-atom supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst according to claim 1, characterized in that: The washing in steps S2, S3 and S4 is performed using anhydrous ethanol and ultrapure water, with each washing cycle being 3 to 6 times. The drying temperature is 50 to 70°C and the drying time is 3 to 6 hours.
6. The method for preparing a Ni-atom supported nitrogen-doped carbon layer wrapped barium titanate piezoelectric catalyst according to claim 1, characterized in that: In step S3, the concentration of the tris(hydroxymethyl)aminomethane buffer solution is 10–20 mmol / L, the pH is ≥8.5, the mass of the barium titanate piezoelectric material is 0.5–1 g, the mass of the dopamine hydrochloride is 0.05–0.1 g, the oil bath temperature is 70–100 °C, and the reaction time is 6–12 h.
7. The method for preparing a Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst according to claim 1, characterized in that: In step S4, the amount of nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst added is 0.5-1g, dispersed in 20-30mL of deionized water, the mass of nickel nitrate hexahydrate added is 58.2-232.7mg, the oil bath temperature is 70-100℃, and the reaction time is 10-12h.
8. The method for preparing a Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst according to claim 1, characterized in that: The high-temperature calcination temperature in step S5 is 600–900°C, the heating rate during the high-temperature calcination process is 2–5°C / min, and the holding time is 1–3 hours.
9. A Ni-supported nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst prepared by the method of preparing a Ni-supported nitrogen-doped carbon layer-coated barium titanate piezoelectric catalyst according to any one of claims 1 to 8, wherein the piezoelectric catalyst, based on a total mass of 100%, contains 0.1 to 2 wt% Ni single atoms.
10. The application of a Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst as described in claim 9 in the treatment of heavy metal complex wastewater.
11. The application of the Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst according to claim 10, characterized in that: The amount of the Ni-doped carbon layer-encapsulated barium titanate piezoelectric catalyst loaded with Ni single atoms added in the treatment of heavy metal complex wastewater is 0.25-2 g / L. The catalytic process is excited by ultrasound with a power of 40-300 W and the reaction time is 0.5-3 h.
12. The application of the Ni single-atom supported nitrogen-doped carbon layer-encapsulated barium titanate piezoelectric catalyst according to claim 10, characterized in that: The heavy metal complexed wastewater is wastewater containing Cu-EDTA, the concentration of Cu-EDTA in the wastewater is 0.1 mmol / L, the pH is 2-10, and the amount of the Ni single-atom supported nitrogen-doped carbon layer encapsulating the barium titanate piezoelectric catalyst is 1 g / L based on the wastewater volume.