Preparation method of ferromagnetic monatomic piezoelectric catalyst, piezoelectric catalyst and application

Abstract

This invention discloses a method for preparing a ferromagnetic single-atom piezoelectric catalyst, the piezoelectric catalyst itself, and its application. The preparation method includes the following steps: weighing ammonium molybdate tetrahydrate and thioacetamide, dissolving them in ultrapure water, and stirring until a colorless and transparent solution is obtained; then adding nickel acetate tetrahydrate, continuing stirring, transferring the mixed solution to a high-pressure reactor, washing after the reaction, and drying to obtain the reaction product; spreading the reaction product evenly in a quartz boat, and finally calcining the reaction product at high temperature under a nitrogen atmosphere, and cooling to successfully prepare the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst. The piezoelectric catalyst prepared by this invention has good piezoelectric catalytic performance and can achieve high organophosphorus degradation efficiency in the treatment of phenylphosphonic acid wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for preparing a ferromagnetic single-atom piezoelectric catalyst, the piezoelectric catalyst itself, and its application. Background Technology

[0002] Agricultural wastewater is a major source of non-point source pollution, with residual organophosphorus pesticides being a core pollutant. While relatively easy to biodegrade, organophosphorus pesticides pose a serious threat to aquatic ecosystems due to their high water solubility and acute toxicity. They directly poison fish, amphibians, and aquatic insects, and disrupt nerve signal transmission by inhibiting acetylcholinesterase, leading to organism death. More problematic is the bioaccumulation of these pesticide residues through the food chain, ultimately affecting higher trophic levels and even human health. Even at low concentrations in water, their long-term "endocrine disruptors" can interfere with the normal physiological functions of aquatic organisms. Physicochemical methods (such as adsorption, advanced oxidation, and chemical hydrolysis) are rapid and efficient, often used for emergency treatment. However, these methods often have significant drawbacks: high cost, high energy consumption, and potential secondary pollution. Chemical hydrolysis may generate more toxic intermediates, and incomplete treatment can actually increase environmental risks. Biodegradation methods are limited by the long acclimatization time of microorganisms and the significant influence of environmental conditions (such as temperature, pH, and coexisting pollutants) on degradation efficiency.

[0003] Piezoelectric catalysis utilizes piezoelectric materials to convert mechanical energy (such as ultrasound and water flow) into chemical energy, enabling efficient degradation of organic pollutants under dark conditions without chemical additives. This technology boasts a wide range of energy sources and rapid reactions, making it a promising green water treatment solution. However, traditional piezoelectric catalysts suffer from low carrier separation efficiency, low mechanical energy capture rate, and a limited number of active sites. Therefore, developing novel piezoelectric catalysts that synergistically enhance piezoelectric response, optimize charge separation, and provide abundant active sites is crucial for promoting the practical application of this technology.

[0004] While external magnetic fields have been proven to enhance piezoelectric catalysis, instilling room-temperature ferromagnetism in piezoelectric materials remains a challenge. Doping piezoelectric materials with room-temperature ferromagnetic single atoms is the optimal solution. However, the main difficulty in combining ferromagnetic single-atom catalysis with piezoelectric catalysis lies in achieving efficient synergy between ferromagnetic ordering, single-atom active sites, and the piezoelectric effect. Firstly, in material design, it is necessary to simultaneously ensure excellent piezoelectricity to generate a built-in electric field under stress and to precisely anchor ferromagnetic metal single atoms at the atomic scale, while maintaining structural stability under dynamic strain. Secondly, regarding the coupling mechanism, the interaction between piezoelectric-induced charge separation and the spin-polarized electronic states of ferromagnetic single atoms is complex. Effectively utilizing piezoelectric polarization charges to regulate the electronic structure and spin state of single-atom active sites to simultaneously optimize the adsorption, activation, and desorption processes of reactants is a core scientific challenge. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems existing in the prior art, and to provide a method for preparing a ferromagnetic single-atom piezoelectric catalyst, the piezoelectric catalyst and its application, which can achieve a high organophosphorus degradation efficiency.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing a ferromagnetic single-atom piezoelectric catalyst includes the following steps:

[0008] S1. Dissolve ammonium molybdate tetrahydrate and thioacetamide in ultrapure water, mix them evenly, and then add nickel acetate tetrahydrate and stir thoroughly to react and obtain a mixture.

[0009] S2. The mixture obtained in step S1 is transferred to a reactor for high-temperature and high-pressure reaction. After the reaction is completed, it is cooled, washed, and dried to obtain the reaction product.

[0010] S3. The reaction product obtained in step S2 is dispersed and spread evenly in a quartz boat, calcined under a nitrogen atmosphere, and cooled to obtain a piezoelectric material with ferromagnetic single-atom doping.

[0011] The preparation method is simple. First, molybdenum disulfide (MoS2) is used as the piezoelectric substrate material. Molybdenum disulfide nanosheets possess excellent piezoelectric properties, generating a built-in electric field, and have a stable structure. Second, nickel single atoms are doped into the molybdenum disulfide structure via a hydrothermal method, endowing it with room-temperature ferromagnetism. When mechanical stress induces polarization charges and a built-in electric field in the piezoelectric material, these charges can migrate directionally to anchored single-atom sites, dynamically controlling its electron density, valence state, and local coordination environment, thereby optimizing its adsorption and activation capabilities for reactants. More importantly, under the influence of a magnetic field, the atomic-level magnetic centers can be effectively polarized, generating directional electron spin alignment. This spin polarization effect not only optimizes the separation and migration efficiency of charges within the piezoelectric material and reduces electron-hole recombination, but also injects spin angular momentum into the reaction system, directly regulating the interaction with key reactants such as oxygen molecules and promoting the generation of highly reactive free radicals. Furthermore, the magnetic field can drive micro-regional mechanical vibrations in ferromagnetic single atoms, further enhancing the piezoelectric effect. This synergistic effect between the magnetic field and piezoelectric catalysis significantly strengthens the degradation kinetics of organic pollutants.

[0012] Further, in step S1, the molar ratio of ammonium molybdate tetrahydrate to thioacetamide is (1~1.2):10; the amount of ammonium molybdate tetrahydrate is 0.05~0.2 mmol, and the stirring time is 0.5~1 h.

[0013] Furthermore, in step S2, the volume of the reactor is 50~100mL, the reaction temperature is 180~200℃, and the time is 20~24h.

[0014] Furthermore, in step S2, the cleaning process uses anhydrous ethanol and ultrapure water, and the washing is performed 3-6 times respectively.

[0015] Furthermore, in step S2, the drying temperature is 50~70℃ and the drying time is 3~6h.

[0016] Furthermore, in step S3, the calcination temperature is 300~500℃, and the holding time is 1~3h.

[0017] Furthermore, in step S3, the heating rate during the calcination process is 2~5 ℃ / min.

[0018] A method for preparing a ferromagnetic single-atom piezoelectric catalyst based on the above-mentioned method is provided. The ferromagnetic single-atom piezoelectric catalyst obtained has a nickel single-atom mass percentage content of 2-8% based on a total mass of 100%.

[0019] Application of a ferromagnetic single-atom piezoelectric catalyst based on the above in phenylphosphonic acid wastewater treatment.

[0020] Furthermore, the amount of ferromagnetic single-atom piezoelectric catalyst added in wastewater treatment is 0.25~2g / L, the catalytic process is excited by ultrasound with a power of 40~300W, and the catalytic reaction is enhanced by an external magnetic field with a magnetic field strength of 120-560mT, with a reaction time of 0.5~10h.

[0021] Furthermore, the concentration of phenylphosphonic acid in the wastewater is 0.1 mmol / L, the pH of the wastewater is 2-14, and the amount of ferromagnetic single-atom piezoelectric catalyst used is 1 g / L based on the volume of wastewater.

[0022] The present invention, by adopting the above-described technical solution, has the following beneficial effects:

[0023] 1. Through the synergistic effect of ferromagnetic single atoms and piezoelectric substrate, directional spin polarization is formed under magnetic field induction, which significantly improves the separation and migration efficiency of piezoelectric charge carriers.

[0024] 2. The atomically dispersed active sites greatly increase the surface reactivity, while the magnetic field can simultaneously enhance the mechanical energy capture and interfacial catalytic reaction kinetics.

[0025] 3. This method has controllable process and good material stability, and maintains high degradation performance in complex aquatic environments, providing a feasible path for promoting the practical application of piezoelectric catalysis technology. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] Figure 1 This is a flowchart of a method for preparing a ferromagnetic single-atom piezoelectric catalyst according to the present invention;

[0028] Figure 2 This is a SEM image of the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst from an embodiment of the present invention.

[0029] Figure 3 This is a SEM image of the comparative MoS2 piezoelectric catalyst of the present invention;

[0030] Figure 4 This is a TEM image of the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst from an embodiment of the present invention.

[0031] Figure 5 This is a TEM image of the comparative MoS2 piezoelectric catalyst of the present invention;

[0032] Figure 6 The XRD patterns of the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst and the comparative MoS2 piezoelectric catalyst of the present invention are shown below.

[0033] Figure 7The Raman spectra of the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst and the comparative MoS2 piezoelectric catalyst of the present invention are shown below.

[0034] Figure 8 The VSM spectra of the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst in the embodiments of the present invention and the comparative MoS2 piezoelectric catalyst are shown below.

[0035] Figure 9 This is a comparison diagram of the degradation of phenylphosphonic acid by the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst in the embodiment of the present invention and the MoS2 piezoelectric catalyst in the comparative example;

[0036] Figure 10 This is a comparison diagram of inorganic phosphorus formation between the Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst of the present invention and the comparative MoS2 piezoelectric catalyst; Detailed Implementation

[0037] A method for preparing a ferromagnetic single-atom piezoelectric catalyst includes the following steps:

[0038] S1. Dissolve ammonium molybdate tetrahydrate and thioacetamide in ultrapure water. The molar ratio of ammonium molybdate tetrahydrate to thioacetamide is (1~1.2):10. The amount of ammonium molybdate tetrahydrate is 0.05~0.2 mmol. After mixing evenly, add nickel acetate tetrahydrate and stir thoroughly for 0.5~1 h to obtain a mixture.

[0039] S2. Transfer the mixture obtained in step S1 to a reactor for high-temperature and high-pressure reaction. The reactor volume is 50-100 mL, the reaction temperature is 180-200℃, and the reaction time is 20-24 h. After the reaction is completed, cool down and wash the mixture. Use anhydrous ethanol and ultrapure water for washing, and wash 3-6 times respectively. Dry the mixture to obtain the reaction product. The drying temperature is 50-70℃, and the drying time is 3-6 h.

[0040] S3. The reaction product obtained in step S2 is dispersed and spread evenly in a quartz boat, and calcined under a nitrogen atmosphere at a temperature of 300~500℃ for 1~3h. The heating rate during calcination is 2~5℃ / min. After cooling, a piezoelectric material with ferromagnetic single-atom doping is obtained.

[0041] A method for preparing a ferromagnetic single-atom piezoelectric catalyst based on the above-mentioned method is provided. The ferromagnetic single-atom piezoelectric catalyst obtained has a nickel single-atom mass percentage content of 2-8% based on a total mass of 100%.

[0042] An application of the aforementioned ferromagnetic single-atom piezoelectric catalyst in the treatment of phenylphosphonic acid wastewater; the concentration of phenylphosphonic acid wastewater is 0.1 mmol / L, the pH of the wastewater is 2-14, the amount of ferromagnetic single-atom piezoelectric catalyst used is 1 g / L based on the volume of wastewater, the amount of ferromagnetic single-atom piezoelectric catalyst added in the wastewater treatment is 0.25-2 g / L, the catalytic process is excited by ultrasound with a power of 40-300W, an external magnetic field with a magnetic field strength of 120-560mT is used to enhance the catalytic reaction, and the reaction time is 0.5-10h.

[0043] 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.

[0044] Example

[0045] Synthesis of Ni-MoS2 ferromagnetic single-atom piezoelectric catalyst:

[0046] (1) Dissolve 176 mg of ammonium molybdate tetrahydrate and 750 mg of thioacetamide in 35 mL of ultrapure water, mix them evenly, and then add 37.4 mg of nickel acetate tetrahydrate and stir the mixture for 0.5 h to obtain a mixture.

[0047] (2) The mixture was transferred to a 50 mL reaction vessel, the reaction temperature was 180 °C, the reaction time was 20 h, and the mixture was allowed to cool naturally. It was washed three times with anhydrous ethanol and ultrapure water, and then placed in a 50 °C oven to dry for 6 h to obtain the reaction product.

[0048] (3) The reaction product was dispersed and spread in a quartz boat and placed in a tube furnace. It was calcined at 400°C for 2 hours under a nitrogen atmosphere. The heating rate during the calcination process was 5°C / min. After calcination, it was cooled to room temperature to obtain the ferromagnetic single-atom piezoelectric catalyst Ni-MoS2.

[0049] Comparative Example

[0050] Synthesis of MoS2 piezoelectric catalysts:

[0051] (1) Dissolve 176 mg of ammonium molybdate tetrahydrate and 750 mg of thioacetamide in 35 mL of ultrapure water and stir thoroughly for 0.5 h to obtain a mixture.

[0052] (2) The mixture was transferred to a 50 mL reaction vessel, the reaction temperature was 180 °C, the reaction time was 20 h, and the mixture was allowed to cool naturally. It was washed three times with anhydrous ethanol and ultrapure water, and then placed in a 50 °C oven to dry for 6 h to obtain the reaction product.

[0053] (3) The reaction product was dispersed and spread in a quartz boat and placed in a tube furnace. It was calcined at 400°C for 2 hours under a nitrogen atmosphere. The heating rate during the calcination process was 5°C / min. After calcination, it was cooled to room temperature to obtain the MoS2 piezoelectric catalyst.

[0054] Material characterization comparison

[0055] like Figure 2 and Figure 3 As shown, the SEM images of both MoS2 and Ni-MoS2 materials reveal them as nanosheets that aggregate into nanoflowers, as... Figure 4 and Figure 5 As shown, the TEM images also exhibit the same morphological features and are stacked in multiple layers; further revealing the structural characteristics of the material, such as... Figure 6 As shown, the XRD pattern reveals that MoS2 exhibits a 2H phase, confirming the intrinsic piezoelectricity of the material. Even after nickel single-atom doping, Ni-MoS2 still possesses the characteristics of a 2H piezoelectric phase, indicating that nickel single-atom doping did not alter its basic structure. Figure 7 As shown, the Raman spectrum exhibits A 1g and E 2g The vibrations further prove the successful synthesis of the piezoelectric phase. In addition, such as... Figure 8 As shown, VSM characterization revealed that the Ni-MoS2 material exhibits room-temperature ferromagnetism, further demonstrating the successful synthesis of the ferromagnetic single-atom piezoelectric catalyst.

[0056] Experimental Example

[0057] Application of the materials prepared in the examples and comparative examples in the degradation of organic pesticide wastewater

[0058] (1) Take 50 mg of Ni-MoS2 material and MoS2 material prepared in the examples and comparative examples, add them to 50 mL of 0.1 mmol / L phenylphosphonic acid solution, and after adsorption for 30 min, trigger the piezoelectric catalytic reaction with an ultrasonic frequency of 40 kHz and a power of 300 W. Take samples at regular intervals and filter them with a 0.22 μm polytetrafluoroethylene filter membrane. Determine the concentration of the target pollutant by high performance liquid chromatography. The maximum reaction time is 10 h. Set up three replicate groups respectively.

[0059] (2) Take 50 mg each of Ni-MoS2 and MoS2 materials prepared in the examples and comparative examples, and add them to 50 mL of 0.1 mmol / L phenylphosphonic acid solution. After adsorption for 30 min, trigger the piezoelectric catalytic reaction with ultrasound at a frequency of 40 kHz and a power of 200 W. In addition, an N52 magnet is introduced during the reaction to provide an external magnetic field with a magnetic field strength of 500 mT. After sampling at regular intervals, filter the sample through a 0.22 μm polytetrafluoroethylene filter membrane and determine the concentration of the target pollutant by high performance liquid chromatography; the maximum reaction time is 10 h; three replicate groups are set up respectively.

[0060] The experimental results are attached. Figure 9 As shown, the results indicate that the piezoelectric degradation effect of MoS2 material on phenylphosphonic acid is limited, with a degradation rate of approximately 46%. The piezoelectric degradation effect of Ni-MoS2 material on phenylphosphonic acid is significantly improved compared to MoS2 material, with a degradation rate of approximately 90% within 10 hours. When a magnetic field is introduced, the piezoelectric degradation effect of MoS2 material on phenylphosphonic acid shows almost no increase, but the piezoelectric degradation effect of Ni-MoS2 material increases from 90% to 100%. Additionally, as shown in the attached figure... Figure 10 As shown, the applied magnetic field also enhances the formation efficiency of inorganic phosphorus. This indicates that the introduction of the magnetic field affects the spin state of ferromagnetic single atoms, increasing the number of polarized spin electrons and thus enhancing the piezoelectric catalytic efficiency.

[0061] 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 solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing a ferromagnetic single-atom piezoelectric catalyst, characterized in that... Includes the following steps: S1. Dissolve ammonium molybdate tetrahydrate and thioacetamide in ultrapure water, mix them evenly, and then add nickel acetate tetrahydrate and stir thoroughly to react and obtain a mixture. S2. The mixture obtained in step S1 is transferred to a reactor for high-temperature and high-pressure reaction. After the reaction is completed, it is cooled, washed, and dried to obtain the reaction product. S3. The reaction product obtained in step S2 is dispersed and spread evenly in a quartz boat, calcined under a nitrogen atmosphere, and cooled to obtain a piezoelectric material with ferromagnetic single-atom doping.

2. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S1, the molar ratio of ammonium molybdate tetrahydrate to thioacetamide is (1~1.2):10; the amount of ammonium molybdate tetrahydrate is 0.05~0.2 mmol; and the stirring time is 0.5~1 h.

3. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S2, the volume of the reactor is 50-100 mL, the reaction temperature is 180-200 °C, and the reaction time is 20-24 h.

4. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S2, the cleaning process uses anhydrous ethanol and ultrapure water, and the washing is performed 3-6 times each.

5. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S2, the drying temperature is 50~70 ℃ and the drying time is 3~6 h.

6. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S3, the calcination temperature is 300~500 ℃ and the holding time is 1~3 h.

7. The method for preparing a ferromagnetic single-atom piezoelectric catalyst according to claim 1, characterized in that: In step S3, the heating rate during the calcination process is 2~5 ℃ / min.

8. A ferromagnetic single-atom piezoelectric catalyst prepared by the method of any one of claims 1-7, wherein the piezoelectric catalyst, based on a total mass of 100%, contains 2-8% nickel single-atom mass percentage.

9. The application of a ferromagnetic single-atom piezoelectric catalyst according to claim 8 in the treatment of phenylphosphonic acid wastewater.

10. The application of the ferromagnetic single-atom piezoelectric catalyst according to claim 9, characterized in that: The ferromagnetic single-atom piezoelectric catalyst is added at a rate of 0.25~2 g / L in wastewater treatment. The catalytic process is excited by ultrasound with a power of 40~300W, and the catalytic reaction is enhanced by an external magnetic field with a magnetic field strength of 120-560mT. The reaction time is 0.5~10h.

11. The application of the ferromagnetic single-atom piezoelectric catalyst according to claim 9, characterized in that: The concentration of phenylphosphonic acid in the wastewater is 0.1 mmol / L, the pH of the wastewater is 2-14, and the amount of the ferromagnetic single-atom piezoelectric catalyst is 1 g / L based on the volume of the wastewater.

Images