Synthesis of a tri-heterojunction type piezoelectric hydrogen evolution catalyst and its efficient piezoelectric catalytic hydrogen production method

Abstract

The present application relates to nanometer piezoelectric hydrogen evolution catalyst electrocatalytic hydrogen production technical field, disclose a kind of synthesis method of three heterojunction type high sensitivity piezoelectric hydrogen evolution catalyst, using hydrothermal-calcination-static self-assembly coupling method, target catalyst is prepared;The method is first by hydrothermal synthesis the heterostructure precursor of molybdenum sulfide / cadmium sulfide, so it has excellent hydrogen evolution performance and conductivity, then the precursor is calcined, the symmetry structure of material is destroyed to produce lattice distortion, so that piezoelectric performance is enhanced, finally by regulating surface charge state, using the electrostatic attraction between positive and negative charges, it is oriented self-assembly with bismuth tungstate, form stable heterojunction, to synthesize target catalyst;And be applied to piezoelectric catalytic hydrogen production system, by ultrasonic piezoelectric hydrogen evolution reaction hydrogen production;The catalyst prepared in the present application has excellent hydrogen evolution performance and stability in piezoelectric catalytic hydrogen production, hydrogen evolution overpotential significantly decreases, hydrogen production significantly increases.

Description

Technical Field

[0001] This invention relates to the field of nanopiezoelectric hydrogen evolution catalyst electrocatalytic hydrogen production technology, specifically to the synthesis of a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst and its efficient piezoelectric catalytic hydrogen production method. Background Technology

[0002] With the rapid development of the world economy, the overuse of non-renewable resources such as oil has led to serious problems such as energy shortages and environmental pollution. Therefore, the development of new energy sources has become an important issue that urgently needs to be addressed. Hydrogen energy has come into people's view due to its wide availability, clean and pollution-free nature, and high calorific value. Currently, the most widely used green hydrogen production method is electrocatalytic water splitting, but it still has problems such as excessive power consumption and low efficiency of the splitting step in the hydrogen evolution process. Preparing a catalyst that can significantly reduce the overpotential in the hydrogen evolution process and improve the efficiency of hydrogen production from water splitting is one of the current key research issues.

[0003] Piezoelectric materials can convert mechanical energy into electrical energy through the piezoelectric effect and construct a polarized internal electric field. Coupled with the piezoelectric effect and the hydrogen evolution process, the piezoelectric polarized internal electric field can assist the water splitting process, further improving the efficiency of hydrogen production, increasing the hydrogen yield, and reducing the hydrogen evolution overpotential, thereby reducing overall energy consumption. However, currently, the hydrogen evolution performance of single piezoelectric materials is relatively poor, and they require significant mechanical energy input, such as high-power ultrasound, to trigger a noticeable piezoelectric effect. Furthermore, their stability in long-term hydrogen evolution processes is unsatisfactory. Considering these backgrounds, this invention aims to prepare a three-heterojunction piezoelectric hydrogen evolution catalyst for efficient piezoelectric catalytic hydrogen production. Summary of the Invention

[0004] To address the problems mentioned in the background section, this invention provides a method for synthesizing a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst. This method primarily couples hydrothermal-calcination-electrostatic self-assembly phases. First, a molybdenum sulfide / cadmium sulfide heterostructure precursor is synthesized hydrothermally. Then, calcination disrupts the material's symmetry structure, causing lattice distortion and enhancing piezoelectric properties. Finally, by controlling the surface charge state and utilizing the electrostatic attraction between positive and negative charges, it undergoes directional self-assembly with bismuth tungstate in the liquid phase to form a stable heterostructure interface, thus preparing a molybdenum sulfide / cadmium sulfide-bismuth tungstate nanopiezoelectric hydrogen evolution material. The molybdenum sulfide / cadmium sulfide-bismuth tungstate piezoelectric hydrogen evolution catalyst prepared by this invention exhibits excellent hydrogen evolution performance, significantly reducing the hydrogen evolution overpotential, increasing hydrogen production, and improving water splitting hydrogen production efficiency. Furthermore, it maintains long-term stability of its overall morphology and performance even under high-power ultrasound.

[0005] Traditional water electrolysis hydrogen production catalysts suffer from low hydrogen production efficiency and high energy consumption during hydrogen evolution. The novel three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst proposed in this invention overcomes these problems, achieving high-efficiency, low-energy-consumption hydrogen production. Furthermore, the poor piezoelectric properties of individual hydrogen evolution catalysts and the generally poor hydrogen evolution performance of piezoelectric catalysts result in high costs for piezoelectric catalytic hydrogen production. The three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst prepared in this invention is a multifunctional catalyst possessing both highly sensitive piezoelectric properties and high hydrogen evolution performance, significantly reducing costs and improving efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst, comprising the following steps: S1. Preparation of molybdenum sulfide / cadmium sulfide precursors: S1-1. Thioacetamide, sodium molybdate dihydrate and cadmium nitrate tetrahydrate are added to deionized water and stirred to obtain solution A. S1-2. Solution A was subjected to a hydrothermal reaction at a temperature of 180-200℃ for 20-24 hours. After the reaction, the product was washed with deionized water and anhydrous ethanol, and then filtered. The product was then placed in a vacuum drying oven and dried at 60℃ for 6 hours to obtain the molybdenum sulfide / cadmium sulfide precursor. S2, Calcination of molybdenum sulfide / cadmium sulfide precursors: The molybdenum sulfide / cadmium sulfide precursor was placed in an alumina boat, and then the alumina boat was placed in a tube furnace for calcination at a temperature of 600-800℃ for 2-4 hours with a heating rate of 3-5℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed to obtain calcined molybdenum sulfide / cadmium sulfide powder. Preparation of S3, bismuth tungstate: S3-1. Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water to obtain solution B; S3-2. Add sodium hydroxide solution to solution B to adjust the pH to 5-7, and stir for 1 hour to obtain solution C; S3-3. Solution C is subjected to a hydrothermal reaction at a temperature of 140-160℃ for 13-15 hours. After the reaction is completed, the white product in the reactor is washed with deionized water and anhydrous ethanol and filtered. The product is then placed in a vacuum drying oven and dried at 60℃ for 6 hours to finally obtain bismuth tungstate powder. Preparation of S4, molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst: S4-1. Disperse bismuth tungstate powder into an ethanol solution to obtain solution D; S4-2. Stir solution D magnetically at 1300-1500 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained in S2 while stirring. Continue stirring, filter after completion, and place the product in a vacuum drying oven to dry at 60℃ for 6 hours to obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0007] Further, in step S1-1, the molar ratio of thioacetamide to sodium molybdate dihydrate is 6:1-8:1, the molar ratio of thioacetamide to cadmium nitrate tetrahydrate is 12:1-20:1, and the molar volume (liter) ratio of thioacetamide to deionized water is 1:2-1:3.

[0008] Further, in step S3-1, the molar ratio of bismuth nitrate pentahydrate to sodium tungstate dihydrate is 1.6:1-2.5:1, and the molar volume (liter) ratio of bismuth nitrate pentahydrate to deionized water is 1:14-1:16.

[0009] Further, in step S4-1, the mass (g) to volume (L) ratio of bismuth tungstate powder to ethanol is 5:1-15:1.

[0010] Further, in step S4-2, the mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:1-3, and the mixture is stirred for 6-9 hours and then filtered.

[0011] The present invention also provides a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst prepared by the preparation method described above.

[0012] The present invention also provides an application of the above-described three heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst in a three-electrode hydrogen production system.

[0013] Further, the application method includes the following steps: Molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst is ground to a mesh size of 60-80 mesh; a mixed suspension of polytetrafluoroethylene and ethanol is added and stirred until homogeneous; the mixture is then coated onto the surface of nickel foam and pressed using a hydraulic press to obtain a cathode working catalyst for a three-electrode hydrogen production system based on a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution material; an electrolytic cell containing the cathode working catalyst of the three-electrode hydrogen production system is placed in an ultrasonic cleaner; a piezoelectric hydrogen evolution reaction is performed by ultrasound; and the generated hydrogen gas is collected by water displacement gas collection method, wherein the ultrasonic power is 130-150 W.

[0014] Furthermore, in the polytetrafluoroethylene and ethanol mixed suspension, the volume ratio of polytetrafluoroethylene to ethanol is 1:1000-1:1500.

[0015] Furthermore, the mass (g) to volume (L) ratio of the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst, polytetrafluoroethylene, and ethanol mixed suspension is 0.4:1-1.6:1.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention adopts a relatively simple and easy hydrothermal-calcination-electrostatic self-assembly phase coupling method to hydrothermally synthesize a heterostructure precursor of molybdenum sulfide / cadmium sulfide. Then, the precursor is calcined and finally electrostatically assembled to synthesize the target catalyst. This makes the three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst prepared by the present invention a multifunctional catalyst with both high-sensitivity piezoelectric performance and high hydrogen evolution performance, thereby reducing costs and improving efficiency.

[0017] (2) The three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst prepared in this invention forms a composite three-heterostructure of molybdenum sulfide, cadmium sulfide, and bismuth tungstate, thereby further enhancing electron transport between structures and optimizing the hydrogen evolution sites to give it excellent conductivity and hydrogen evolution performance. The calcination of the intermediate material destroys the symmetrical structure of the material, resulting in lattice distortion, which enhances the piezoelectric performance. In summary, the three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst material prepared in this invention has excellent piezoelectric hydrogen evolution performance.

[0018] (3) The three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst prepared by the present invention can significantly reduce the reaction energy barrier of hydrogen evolution reaction under the action of ultrasound. Its high-sensitivity piezoelectric characteristics can form a polarized internal electric field after the application of ultrasound, promote the hydrogen evolution reaction, significantly reduce the hydrogen evolution overpotential, increase the hydrogen production, improve the hydrogen production efficiency of water cracking, and at the same time maintain the long-term stability of overall morphology and performance under high-power ultrasound. Attached Figure Description

[0019] Figure 1 A flowchart illustrating the synthesis of a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst and its efficient piezoelectric catalytic hydrogen production method; Figure 2 A graph showing the hydrogen evolution rate of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst; Figure 3 A comparison of piezoelectric currents of a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0022] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0023] like Figure 1 As shown in the embodiments of this application, a synthesis of a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst and a highly efficient piezoelectric catalytic hydrogen production method thereof are provided, including the following steps: Step 1: Preparation of molybdenum sulfide / cadmium sulfide precursors 1) Add a certain molar ratio of thioacetamide, sodium molybdate dihydrate and cadmium nitrate tetrahydrate to deionized water and stir for 15 min to obtain solution A; 2) Transfer solution A to a hydrothermal reactor lined with polytetrafluoroethylene (PTFE) for hydrothermal reaction at a temperature of 180-200℃ for 20-24 hours. After the reaction, wash the black product in the reactor with deionized water and anhydrous ethanol, then filter. The product is then placed in a vacuum drying oven at 60℃. The precursors were dried at ℃ for 6 hours to obtain molybdenum sulfide / cadmium sulfide precursors.

[0024] Step 2: Calcination of molybdenum sulfide / cadmium sulfide precursors The molybdenum sulfide / cadmium sulfide precursor catalyst was placed in an alumina boat, which was then placed in a tube furnace for calcination at a temperature of 600-800℃ for 2-4 hours at a heating rate of 3-5℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed.

[0025] Step 3: Preparation of Bismuth Tungstate 1) Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water in a certain molar ratio to obtain solution B; 2) Add sodium hydroxide solution to solution B to adjust the pH to 5-7, and stir for 1 hour to obtain solution C; 3) Transfer solution C to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 140-160℃ for 13-15 hours. After the reaction, wash the white product in the reactor with deionized water and anhydrous ethanol, and filter. Then, dry the product in a vacuum drying oven at 60℃ for 6 hours to obtain bismuth tungstate powder.

[0026] Step 4: Preparation of molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst 1) Disperse bismuth tungstate powder into sufficient ethanol solution to obtain solution D; 2) Stir the solution D magnetically at 1300-1500 rpm, and add the above-mentioned calcined molybdenum sulfide / cadmium sulfide powder while stirring. After high-speed magnetic stirring, filter the solution and place the product in a vacuum drying oven to dry at 60°C for 6 hours to finally obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0027] The application of a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst in a three-electrode hydrogen production system includes the following steps: The catalyst prepared above was ground, and a mixed suspension of polytetrafluoroethylene and ethanol was added to it. The mixture was stirred and mixed evenly, and then coated onto the surface of nickel foam. The mixture was pressed using a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0028] In one embodiment of the present invention, the molar ratio of thioacetamide, sodium molybdate dihydrate, and cadmium nitrate tetrahydrate in step one is x:y:z, where 6 ≤ x / y < 8 and 12 ≤ x / z < 20.

[0029] In one embodiment, the molar ratio of bismuth nitrate pentahydrate to sodium tungstate dihydrate in step three is a:b, where 1.6 ≤ a / b < 2.5.

[0030] In one embodiment of the present invention, the mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder added in step four is m:n, where 1≤m / n<3, and the stirring time is 6-9h.

[0031] In one embodiment of the present invention, in the application of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst in a three-electrode hydrogen production system, the ratio of the catalyst mass (grams) to the volume (liters) of the added polytetrafluoroethylene ethanol mixed suspension is i:j, wherein 0.4≤i / j<1.6. The mixture is stirred and mixed evenly, and then coated on the surface of nickel foam. The mixture is then pressed using a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0032] The electrolyzer of the three-electrode hydrogen production system containing the catalyst sample from Example 2 was placed in an ultrasonic cleaner, and a piezoelectric hydrogen evolution reaction was performed using ultrasound. The amount of hydrogen produced over 3 hours was collected by water displacement collection method, and the hydrogen production rate of the catalyst was obtained as shown in the attached figure. Figure 2 As shown, the hydrogen production rates measured in four separate tests were 3.745, 3.736, 3.728, and 3.713 mmol g, respectively. -1 The average hydrogen production rate over 12 hours was 3.73 mmol g. -1 The hydrogen production rate decay rate was only 0.85%, indicating that the three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst of this invention has a high hydrogen production rate and efficiency, while also exhibiting excellent stability. The three-electrode hydrogen production system was connected to an electrochemical workstation, and the piezoelectric operating current of the catalyst was measured. The operating piezoelectric current characterizes the piezoelectric performance of the catalyst, as shown in the attached figure. Figure 3 The average working piezoelectric current of the catalyst of this invention was measured to be 3.08 mA cm⁻¹. -2The piezoelectric properties were significantly higher than those of other comparative catalysts, indicating that it possesses superior piezoelectric performance compared to other comparative catalysts. Simultaneously, linear sweep voltammetry electrochemical tests were performed on the three-electrode hydrogen production system electrolyzer containing the catalyst sample from Example 2 using an electrochemical workstation, comparing the piezoelectric properties at a current density of 10 mA cm⁻¹. -2 The corresponding overpotential value is given. A smaller overpotential value indicates better hydrogen evolution performance of the catalyst. The measured overpotential for hydrogen evolution of the catalyst is only 60.3 mV (@10 mA cm⁻¹). -2 This indicates that the catalyst of the present invention possesses excellent hydrogen evolution catalytic performance. In summary, the three heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst of the present invention simultaneously exhibits excellent hydrogen evolution, piezoelectric catalytic, and stability properties. Example 1

[0033] Preparation of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst: Step 1: Preparation of molybdenum sulfide / cadmium sulfide precursors 1) Thioacetamide, sodium molybdate dihydrate, and cadmium nitrate tetrahydrate in a molar ratio of 12:2:1 were added to deionized water, wherein the molar volume ratio (liters) of thioacetamide to deionized water was 1:2 and the molar amount of thioacetamide was 0.012 mol. The mixture was stirred for 15 min to obtain solution A. 2) Transfer solution A to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 200 °C for 24 h. After the reaction, wash the black product in the reactor with deionized water and anhydrous ethanol and filter it. Then place the product in a vacuum drying oven and dry it at 60 °C for 6 h to obtain the molybdenum sulfide / cadmium sulfide precursor.

[0034] Step 2: Calcination of molybdenum sulfide / cadmium sulfide precursors The molybdenum sulfide / cadmium sulfide precursor catalyst was placed in an alumina boat, which was then placed in a tube furnace for calcination at 800℃ for 4 hours at a heating rate of 5℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed to obtain calcined molybdenum sulfide / cadmium sulfide powder.

[0035] Step 3: Preparation of Bismuth Tungstate 1) Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water at a molar ratio of 1.6:1, wherein the molar volume ratio (liters) of bismuth nitrate pentahydrate to deionized water is 1:14, and the molar amount of bismuth nitrate pentahydrate is 0.002 mol, to obtain solution B; 2) Add sodium hydroxide solution to solution B to adjust the pH to 7, and stir for 1 hour to obtain solution C; 3) Solution C was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at 160°C for 15 hours. After the reaction, the white product in the reactor was washed with deionized water and anhydrous ethanol and filtered. The product was then dried in a vacuum drying oven at 60°C for 6 hours to obtain bismuth tungstate powder.

[0036] Step 4: Preparation of molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst 1) Bismuth tungstate powder was dispersed in an ethanol solution, wherein the mass (g) to volume (L) ratio of bismuth tungstate powder to ethanol was 5:1, and the mass of bismuth tungstate powder was 0.1 g, resulting in solution D. 2) Stir solution D magnetically at 1500 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained above while stirring. The mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:1. Continue stirring for 9 hours. After the stirring is completed, filter the solution and place the product in a vacuum drying oven to dry at 60°C for 6 hours to obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0037] Application of tri-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst in three-electrode hydrogen production system: Add 50 μl of polytetrafluoroethylene to 50 ml of ethanol solution and stir for 1 h to obtain a polytetrafluoroethylene-ethanol mixed suspension. Weigh 20 mg of catalyst (mass (g) to solution volume (L) in a ratio of 8:5 to the polytetrafluoroethylene-ethanol mixed suspension, and stir to mix evenly. Coat the mixture onto the surface of nickel foam and press it using a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0038] An electrolytic cell equipped with a three-electrode hydrogen production system was placed in an ultrasonic cleaner, and a piezoelectric hydrogen evolution reaction was performed using 150 W ultrasound. The produced hydrogen was collected by water displacement collection, yielding a hydrogen production rate of 1.25 mmol g. -1 h -1 The hydrogen evolution overpotential of the catalyst under ultrasonic conditions was found to be 58.9 mV (@10 mA cm⁻¹) by connecting to an electrochemical workstation. -2 The measured piezoelectric current was 3.12 mA cm⁻¹. -2 The catalyst can reach 20 mA cm -2 The catalyst operated stably at a current density for 100 hours, indicating that it has high hydrogen production efficiency, excellent piezoelectric properties, and durability. Example 2

[0039] Preparation of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst: Step 1: Preparation of molybdenum sulfide / cadmium sulfide precursors 1) Thioacetamide, sodium molybdate dihydrate, and cadmium nitrate tetrahydrate in a molar ratio of 14:2:1 were added to deionized water, where the molar volume ratio (in liters) of thioacetamide to deionized water was 1:2.5 and the molar amount of thioacetamide was 0.012 mol. The mixture was stirred for 15 min to obtain solution A. 2) Solution A was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at 190°C for 22 h. After the reaction, the black product in the reactor was washed with deionized water and anhydrous ethanol and filtered. The product was then placed in a vacuum drying oven and dried at 60°C for 6 h to obtain the molybdenum sulfide / cadmium sulfide precursor.

[0040] Step 2: Calcination of molybdenum sulfide / cadmium sulfide precursors The molybdenum sulfide / cadmium sulfide precursor catalyst was placed in an alumina boat, which was then placed in a tube furnace for calcination at a temperature of 700℃ for 3 hours at a heating rate of 4℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed to obtain calcined molybdenum sulfide / cadmium sulfide powder.

[0041] Step 3: Preparation of Bismuth Tungstate 1) Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water at a molar ratio of 2:1, wherein the molar volume ratio (liters) of bismuth nitrate pentahydrate to deionized water is 1:15, and the molar amount of bismuth nitrate pentahydrate is 0.002 mol, to obtain solution B; 2) Add sodium hydroxide solution to solution B to adjust the pH to 6, and stir for 1 hour to obtain solution C; 3) Transfer solution C to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 150°C. The reaction was carried out at ℃ for 14 hours. After the reaction was completed, the white product in the reactor was washed with deionized water and anhydrous ethanol and filtered. Then the product was dried in a vacuum drying oven at 60℃ for 6 hours to finally obtain bismuth tungstate powder.

[0042] Step 4: Preparation of molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst 1) Bismuth tungstate powder was dispersed in an ethanol solution, wherein the mass (g) to volume (L) ratio of bismuth tungstate powder to ethanol was 10:1, and the mass of bismuth tungstate powder was 0.1 g, resulting in solution D. 2) Stir solution D magnetically at 1400 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained above while stirring. The mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:2. Continue stirring for 8 hours. After the stirring is completed, filter the solution and place the product in a vacuum drying oven to dry at 60°C for 6 hours to obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0043] Application of tri-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst in three-electrode hydrogen production system: Add 40 μl of polytetrafluoroethylene to 50 ml of ethanol solution and stir for 1 h to obtain a polytetrafluoroethylene-ethanol mixed suspension. Weigh 20 mg of catalyst and polytetrafluoroethylene-ethanol mixed suspension with a mass (g) to solution volume (L) ratio of 1:1. Stir and mix evenly, and coat the mixture onto the surface of nickel foam. Press the mixture using a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0044] An electrolytic cell equipped with a three-electrode hydrogen production system was placed in an ultrasonic cleaner, and a piezoelectric hydrogen evolution reaction was performed using 140 W ultrasound. The produced hydrogen was collected by water displacement, yielding a hydrogen production rate of 1.21 mmol g. -1 h -1 The hydrogen evolution overpotential of the catalyst under ultrasonic conditions was determined to be 60.3 mV (@10 mA cm⁻¹) by electrochemical workstation testing. -2 The measured piezoelectric current was 3.08 mA cm⁻¹. -2 The catalyst can reach 20 mA cm -2 The catalyst operated stably at a current density for 100 hours, indicating that it has high hydrogen production efficiency, excellent piezoelectric properties, and durability. Example 3

[0045] Preparation of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst: Step 1: Preparation of molybdenum sulfide / cadmium sulfide precursors 1) Thioacetamide, sodium molybdate dihydrate, and cadmium nitrate tetrahydrate in a molar ratio of 40:5:2 were added to deionized water, where the molar volume ratio (in liters) of thioacetamide to deionized water was 1:3 and the molar amount of thioacetamide was 0.012 mol. The mixture was stirred for 15 min to obtain solution A. 2) Solution A was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at 180°C for 20 h. After the reaction, the black product in the reactor was washed with deionized water and anhydrous ethanol and filtered. The product was then placed in a vacuum drying oven and dried at 60°C for 6 h to obtain the molybdenum sulfide / cadmium sulfide precursor.

[0046] Step 2: Calcination of molybdenum sulfide / cadmium sulfide precursors The molybdenum sulfide / cadmium sulfide precursor catalyst was placed in an alumina boat, which was then placed in a tube furnace for calcination at a temperature of 600℃ for 2 hours at a heating rate of 3℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed to obtain calcined molybdenum sulfide / cadmium sulfide powder.

[0047] Step 3: Preparation of Bismuth Tungstate 1) Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water at a molar ratio of 5:2, wherein the molar volume ratio (liters) of bismuth nitrate pentahydrate to deionized water is 1:16, and the molar amount of bismuth nitrate pentahydrate is 0.002 mol, to obtain solution B; 2) Add sodium hydroxide solution to solution B to adjust the pH to 5, and stir for 1 hour to obtain solution C; 3) Transfer solution C to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 140°C. The reaction was carried out at ℃ for 13 hours. After the reaction was completed, the white product in the reactor was washed with deionized water and anhydrous ethanol and filtered. Then the product was placed in a vacuum drying oven and dried at 60℃ for 6 hours to finally obtain bismuth tungstate powder.

[0048] Step 4: Preparation of molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst 1) Bismuth tungstate powder was dispersed in an ethanol solution, wherein the mass (g) to volume (L) ratio of bismuth tungstate powder to ethanol was 15:1, and the mass of bismuth tungstate powder was 0.1 g, resulting in solution D. 2) Stir solution D magnetically at 1300 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained above while stirring. The mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:3. Continue stirring for 6 hours. After the stirring is completed, filter the solution and place the product in a vacuum drying oven to dry at 60°C for 6 hours to obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0049] Application of tri-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst in three-electrode hydrogen production system: Add 30 μl of polytetrafluoroethylene to 50 ml of ethanol solution and stir for 1 h to obtain a polytetrafluoroethylene-ethanol mixed suspension. Weigh the catalyst (mass (g) to solution volume (L) ratio of 2:5) and the polytetrafluoroethylene-ethanol mixed suspension, where the mass of the catalyst is 20 mg. Stir and mix evenly, and coat it on the surface of nickel foam. Press it with a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0050] An electrolytic cell equipped with a three-electrode hydrogen production system was placed in an ultrasonic cleaner, and a piezoelectric hydrogen evolution reaction was performed using 130 W ultrasound. The produced hydrogen was collected by water displacement, yielding a hydrogen production rate of 1.22 mmol g. -1 h -1 The hydrogen evolution overpotential of the catalyst under ultrasonic conditions was determined to be 63.7 mV (@10 mA cm⁻¹) by electrochemical workstation testing. -2 The measured piezoelectric current was 3.10 mA cm⁻¹. -2 The catalyst can reach 20 mA cm -2 The catalyst operated stably at a current density for 100 hours, indicating that it has high hydrogen production efficiency, excellent piezoelectric properties, and durability. Comparative Example

[0051] Preparation of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst: Step 1: Preparation of molybdenum sulfide / cadmium sulfide precursors 1) Thioacetamide, sodium molybdate dihydrate, and cadmium nitrate tetrahydrate in a molar ratio of 13:3:1 were added to deionized water, where the molar volume ratio (in liters) of thioacetamide to deionized water was 1:3.5 and the molar amount of thioacetamide was 0.012 mol. The mixture was stirred for 15 min to obtain solution A. 2) Transfer solution A to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 150°C for 18 hours. After the reaction, wash the black product in the reactor with deionized water and anhydrous ethanol and filter it. Then place the product in a vacuum drying oven and dry it at 60°C for 6 hours.

[0052] Step 2: Calcination of molybdenum sulfide / cadmium sulfide precursors The molybdenum sulfide / cadmium sulfide precursor catalyst was placed in an alumina boat, which was then placed in a tube furnace for calcination at 500°C for 1.5 h at a heating rate of 2.5°C / min. After calcination, the alumina boat was cooled to room temperature and removed.

[0053] Step 3: Preparation of Bismuth Tungstate 1) Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water at a molar ratio of 3:1, wherein the molar volume ratio (liters) of bismuth nitrate pentahydrate to deionized water is 1:17, and the molar amount of bismuth nitrate pentahydrate is 0.002 mol, to obtain solution B; 2) Add sodium hydroxide solution to solution B to adjust the pH to 7, and stir for 1 hour to obtain solution C; 3) Transfer solution C to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 130°C. The reaction was carried out at ℃ for 12 hours. After the reaction was completed, the white product in the reactor was washed with deionized water and anhydrous ethanol and filtered. Then the product was dried in a vacuum drying oven at 60℃ for 6 hours to finally obtain bismuth tungstate powder.

[0054] Step 4: Preparation of molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst 1) Bismuth tungstate powder was dispersed in an ethanol solution, wherein the mass (g) to volume (L) ratio of bismuth tungstate powder to ethanol was 16:1, and the mass of bismuth tungstate powder was 0.1 g, resulting in solution D. 2) Stir solution D magnetically at 1100 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained above while stirring. The mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:4. Continue stirring for 4 hours. After the stirring is completed, filter the solution and place the product in a vacuum drying oven to dry at 60°C for 6 hours to obtain the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst.

[0055] Application of tri-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst in three-electrode hydrogen production system: Add 30 μl of polytetrafluoroethylene to 50 ml of ethanol solution and stir for 1 h to obtain a polytetrafluoroethylene-ethanol mixed suspension. Weigh 20 mg of catalyst and polytetrafluoroethylene-ethanol mixed suspension with a mass (g) to solution volume (L) ratio of 2:1. Stir and mix evenly, and coat the mixture onto the surface of nickel foam. Press the mixture using a hydraulic press to obtain the cathode working catalyst of the three-electrode hydrogen production system of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution material.

[0056] An electrolytic cell equipped with a three-electrode hydrogen production system was placed in an ultrasonic cleaner, and a piezoelectric hydrogen evolution reaction was performed using 100 W ultrasound. The generated hydrogen was collected by water displacement, yielding a hydrogen production rate of 0.33 mmol g. -1 h -1 The hydrogen evolution overpotential of the catalyst under ultrasonic conditions was determined to be 115.8 mV (@10 mA cm⁻¹) by electrochemical workstation testing. -2 The measured piezoelectric current was 1.20 mA cm⁻¹. -2 The catalyst was at 20 mA cm⁻¹ -2 Significant performance degradation occurs after 20 hours of operation at current density.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0058] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a three-heterojunction type highly sensitive piezoelectric hydrogen evolution catalyst, characterized in that, Includes the following steps: S1. Preparation of molybdenum sulfide / cadmium sulfide precursors: S1-1. Thioacetamide, sodium molybdate dihydrate and cadmium nitrate tetrahydrate are added to deionized water and stirred to obtain solution A. S1-2. Solution A was subjected to a hydrothermal reaction at a temperature of 180-200℃ for 20-24 hours. After the reaction, the product was washed with deionized water and anhydrous ethanol, and then filtered. The product was then placed in a vacuum drying oven and dried at 60℃ for 6 hours to obtain the molybdenum sulfide / cadmium sulfide precursor. S2, Calcination of molybdenum sulfide / cadmium sulfide precursors: The molybdenum sulfide / cadmium sulfide precursor was placed in an alumina boat, and then the alumina boat was placed in a tube furnace for calcination at a temperature of 600-800℃ for 2-4 hours with a heating rate of 3-5℃ / min. After the calcination was completed, the alumina boat was cooled to room temperature and removed to obtain calcined molybdenum sulfide / cadmium sulfide powder. Preparation of S3, bismuth tungstate: S3-1. Dissolve bismuth nitrate pentahydrate and sodium tungstate dihydrate in deionized water to obtain solution B; S3-2. Add sodium hydroxide solution to solution B to adjust the pH to 5-7, and stir for 1 hour to obtain solution C; S3-3. Solution C is subjected to a hydrothermal reaction at a temperature of 140-160℃ for 13-15 hours. After the reaction is completed, the white product in the reactor is washed with deionized water and anhydrous ethanol and filtered. The product is then placed in a vacuum drying oven and dried at 60℃ for 6 hours to finally obtain bismuth tungstate powder. Preparation of S4, molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst: S4-1. Disperse bismuth tungstate powder into an ethanol solution to obtain solution D; S4-2. Stir solution D magnetically at 1300-1500 rpm, and add the calcined molybdenum sulfide / cadmium sulfide powder obtained in S2 while stirring. Continue stirring, filter after completion, and place the product in a vacuum drying oven to dry at 60℃ for 6 hours to obtain molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst. In step S1-1, the molar ratio of thioacetamide to sodium molybdate dihydrate is 6:1-8:1; the molar ratio of thioacetamide to cadmium nitrate tetrahydrate is 12:1-20:1; and the molar volume ratio of thioacetamide to deionized water is 1:2-1:3, in mol / L. In step S3-1, the molar ratio of bismuth nitrate pentahydrate to sodium tungstate dihydrate is 1.6:1-2.5:1; the molar volume ratio of bismuth nitrate pentahydrate to deionized water is 1:14-1:16, in mol / L. In step S4-1, the mass-to-volume ratio of bismuth tungstate powder to ethanol is 5:1-15:1, with units of g / L. In step S4-2, the mass ratio of bismuth tungstate powder to calcined molybdenum sulfide / cadmium sulfide powder is 1:1-3.

2. The preparation method of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst according to claim 1, characterized in that, In step S4-2, the mixture is stirred for 6-9 hours and then filtered.

3. A three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst prepared by the preparation method according to any one of claims 1-2.

4. The application of a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst prepared by the preparation method according to any one of claims 1-2 in a three-electrode hydrogen production system.

5. The application of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst according to claim 4 in a three-electrode hydrogen production system, characterized in that, The application method includes the following steps: Molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst is ground to a mesh size of 60-80 mesh; a mixed suspension of polytetrafluoroethylene and ethanol is added and stirred until homogeneous; the mixture is then coated onto the surface of nickel foam and pressed using a hydraulic press to obtain a cathode working catalyst for a three-electrode hydrogen production system based on a three-heterojunction type high-sensitivity piezoelectric hydrogen evolution material; an electrolytic cell containing the cathode working catalyst of the three-electrode hydrogen production system is placed in an ultrasonic cleaner; a piezoelectric hydrogen evolution reaction is performed by ultrasound; and the generated hydrogen gas is collected by water displacement gas collection method, wherein the ultrasonic power is 130-150 W.

6. The application of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst according to claim 5 in a three-electrode hydrogen production system, characterized in that, In the polytetrafluoroethylene and ethanol mixed suspension, the volume ratio of polytetrafluoroethylene to ethanol is 1:1000-1:1500.

7. The application of the three heterojunction type high-sensitivity piezoelectric hydrogen evolution catalyst according to claim 5 in a three-electrode hydrogen production system, characterized in that, The mass-to-volume ratio of the molybdenum sulfide / cadmium sulfide-bismuth tungstate catalyst, polytetrafluoroethylene, and ethanol mixed suspension is 0.4:1-1.6:1, in g / L.

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