Preparation and application of transition metal doped oxygen vacancy-bismuth elemental catalyst

Abstract

The application relates to a transition metal doped oxygen vacancy-bismuth element containing catalyst preparation and application, and belongs to the field of catalysis. The catalyst is a microsphere composed of transition metal nickel doped nanometer layered BiOCl, and oxygen vacancies and part of metal bismuth (Bi 0 ) nanoparticles are uniformly distributed on the surface of the microsphere. Ethylene glycol weak reductant is used as a reaction solvent, and nickel source is added at one time, and under the action of ethylene glycol, the dissolution of the bismuth source Bi-O nucleation generates nanometer microspheres. The photocatalyst of the application is dissolved in pure water without adding any sacrificial agent, and under the joint action of a 300W xenon lamp and an ultrasonic instrument, a certain concentration of hydrogen peroxide is generated by oxidation, the energy band of the catalyst is changed due to the doping of the metal nickel, the light absorption range is expanded, and the separation ability of photo-generated carriers is improved.

Description

Technical Field

[0001] This invention belongs to the field of renewable energy photocatalytic materials, and relates to the preparation of a transition metal-doped oxygen vacancy-bismuth elemental catalyst and its application in the green preparation of hydrogen peroxide energy. Background Technology

[0002] Currently, the main industrial production method for hydrogen peroxide is the anthraquinone process. Its main drawbacks include the need for high temperature and pressure conditions, the use of organic solvents, and the generation of large amounts of organic waste liquid, causing environmental pollution. In light of these drawbacks, new production methods are constantly being developed and researched. Among these, photocatalysis technology has shown significant results and is environmentally friendly, utilizing solar energy instead of fossil fuel heating and operating at ambient temperature and pressure. Although photocatalysis technology shows great potential in hydrogen peroxide production, semiconductor photocatalysts suffer from the problem of rapid recombination of photogenerated carriers, which severely hinders their solar energy conversion efficiency and becomes a key bottleneck for the practical application of this technology. To solve this problem, in recent years, researchers have turned their attention to piezoelectric photocatalysis technology, which aims to combine the piezoelectric effect with photocatalysis. It uses mechanical energy such as ultrasonic vibration and fluid flow to excite a piezoelectric potential inside the semiconductor, thereby forming an internal electric field. This field drives the efficient separation and migration of photogenerated carriers, ultimately achieving a synergistic enhancement of catalytic performance.

[0003] Layered bismuth-based photocatalysts have been extensively studied in the field of photocatalysis because bismuth-based materials are non-toxic, harmless, and environmentally friendly. Their layered structure endows them with high chemical and thermal stability, providing channels for charge transport. Among them, BiOCl is the simplest bismuth-based layered material, [Bi₂O₂]. 2+ Alternating axial arrangement with halogen elements and connected by van der Waals forces, the unique structure of BiOCl leads to a non-uniform charge distribution, creating a natural electrostatic field within the crystal structure. Given this advantage, a piezoelectric-photocatalytic system can be constructed through the coupling of mechanical oscillations (such as ultrasound) and light. The piezoelectric effect further facilitates the polarization of the internal structure, generating an internal electric field that further separates photogenerated carriers, extends their lifetime, and thus enhances catalytic performance.

[0004] Recent studies on hydrogen peroxide production from BiOCl have shown that BiOCl suffers from a narrow visible light response range and easy recombination of photogenerated carriers. Major modification methods include defect engineering, heterostructure construction, elemental doping, crystal plane manipulation, and noble metal deposition. The most significant advantage of transition metal doping is that it narrows the bandgap by introducing impurity energy levels, extending the photoresponse range from the ultraviolet to the visible light region. Transition metals can also act as electron or hole traps to effectively suppress electron-hole recombination. Research has also found that most modification methods to improve hydrogen peroxide yield involve constructing heterostructures, which are more costly and difficult to operate compared to metal doping. Developing a simple, low-energy-consumption one-step synthesis strategy is crucial for optimizing the surface properties of bismuth-based catalysts and expanding their environmental applications. Research on transition metal doping shows a significant development trend. Summary of the Invention

[0005] The main pathways for photocatalytic hydrogen peroxide production are the two-electron oxygen reduction reaction and the two-electron water oxidation reaction. These typically require the addition of sacrificial alcohols such as methanol, ethanol, or isopropanol to capture holes and suppress the competing reaction with oxygen. While research on BiOCl for hydrogen peroxide production has been extensive in the last three years, it still faces challenges such as low carrier mobility, limiting the transport of photogenerated charges from the bulk phase to the surface phase, affecting the redox reaction rate on its surface, and a lack of systematic exploration. Further in-depth research is urgently needed. This invention addresses the advantages and existing problems of BiOCl materials by modifying them to improve catalytic performance. Transition metal Ni has been extensively studied in photocatalytic carbon dioxide reduction. It can not only increase the band gap but also successfully incorporate active substances such as oxygen vacancies due to lattice distortion caused by differences in ionic radii. Nickel itself also possesses an ionic resonance effect, which is beneficial for the separation of photogenerated charges. The catalyst described is synthesized in one step using ethylene glycol as a weak reducing agent as the reaction solvent and simultaneously adding a nickel source. The ethylene glycol promotes the dissolution of the bismuth source and the nucleation of Bi-O to form nanospheres. This synthetic strategy offers significant advantages such as ease of operation, mild reaction conditions, and green sustainability, effectively avoiding key technical bottlenecks in traditional preparation methods, including cumbersome multi-step synthesis processes, reliance on strong reducing reagents, and high-energy-consuming post-processing. The synthesized catalyst's structure and performance were synergistically optimized, exhibiting excellent light absorption characteristics, high charge separation efficiency, and significant piezoelectric response, enabling it to efficiently produce hydrogen peroxide and providing a design strategy for hydrogen peroxide production research.

[0006] To address the technical challenges of using environmental nanomaterials in the hydrogen peroxide production process, the present invention provides the following specific technical solution:

[0007] A layered bismuth-based catalyst, BiOCl-Ni, containing oxygen vacancies and metal doping, is described. The catalyst consists of nanospheres composed of layered BiOCl nanospheres doped with the transition metal nickel. Oxygen vacancies and partially distributed metallic bismuth (Bi) are uniformly distributed on the surface of the microspheres.0 Nanoparticles.

[0008] According to the present invention, the catalysts synthesized by using ethylene glycol and dopants are all in the form of nanospheres, and the microspheres are uniformly distributed with a diameter between 800-840 nm.

[0009] According to the present invention, transition metal nickel was successfully incorporated into BiOCl nanospheres, resulting in the generation of oxygen vacancies and the precipitation of a small amount of elemental bismuth.

[0010] According to the present invention, the catalyst exhibits visible light absorption characteristics. The catalyst also possesses good crystallinity.

[0011] The catalyst of this invention is synthesized in one step by a solvothermal method. The weak reducing properties of ethylene glycol and the introduction of oxygen vacancies and bismuth element by metal doping, along with the synergistic effect of surface defects, enable the prepared catalyst to increase the yield of hydrogen peroxide under the combined action of piezoelectricity and light.

[0012] This invention provides a method for preparing the aforementioned nickel-doped BiOCl, wherein the method involves mixing a bismuth source, a chlorine source, a nickel source, and a weak reducing agent in ethylene glycol, and then preparing the BiOCl via a hydrothermal method.

[0013] According to the present invention, the method includes the following steps:

[0014] (1) Dissolve the bismuth source in a certain amount of ethylene glycol, stir, and label it as solution A; dissolve the chlorine source in ethylene glycol, stir, and label it as solution B; slowly add solution B to solution A, stir to make it fully mixed to form a mixture C;

[0015] (2) Add the nickel source to the mixture C and stir again to obtain a mixed solution;

[0016] (3) Transfer the mixed solution from step (2) into a high-pressure reactor and place it in a vacuum oven for hydrothermal reaction;

[0017] (4) After the hydrothermal reaction, the product is cooled to room temperature, washed several times with a mixed solvent of deionized water and ethanol in a volume ratio of 4-24:1-6, and dried in an oven (50-80℃) to obtain the nickel-doped BiOCl catalyst.

[0018] According to the present invention, the bismuth source is selected from one or more of bismuth nitrate pentahydrate, bismuth oxide, and bismuth chloride; the chlorine source is one or more of potassium chloride, sodium chloride, or hexadecyltrimethylammonium chloride; and the nickel source is one or more of nickel chloride hexahydrate and nickel nitrate. The optimal bismuth source, chlorine source, and nickel source are bismuth nitrate pentahydrate, potassium chloride, and nickel chloride hexahydrate, respectively.

[0019] According to the present invention, the amounts of bismuth source and chlorine source added are such that the molar ratio of bismuth to chlorine is 1:1, which conforms to the molar ratio of the target catalyst. The amount of nickel source added is 8% of the mass of the bismuth source.

[0020] According to the present invention, in steps (1) and (2), the stirring time is 20-40 min, with an optimal value of 30 min, and the stirring rate is 200-600 r / min, with an optimal value of 500 r / min.

[0021] According to the present invention, the heating temperature of the hydrothermal method in step (3) is 150-200℃, and the heating time is 8-15h. The optimal heating temperature and heating time are 160℃ and 12h, respectively.

[0022] According to the present invention, in step (4), the washing method involves discarding the supernatant in the heated reaction vessel and retaining the precipitate. The precipitate is washed five times with a mixture of deionized water and anhydrous ethanol at the optimal speed of 500 r / min, and then centrifuged at 5000-8000 r / min to collect the centrifuged material. The optimal centrifugation speed is 7500 r / min.

[0023] According to the present invention, the drying temperature in step (4) is 50-80℃ and the drying time is 8-15h. The optimal heating temperature and heating time are 70℃ and 12h, respectively.

[0024] The application of the catalyst described above in this invention is for the production of hydrogen peroxide in pure water.

[0025] According to the present invention, the catalyst is activated by a combination of visible light irradiation and ultrasound. The light source is a 300W xenon lamp with a main wavelength of λ≥420nm, and the ultrasound is performed using an ultrasonic instrument with a frequency of 40kHz and a power of 40~300W. In this invention, the optimal power of the ultrasonic instrument is 100W.

[0026] The specific steps for producing hydrogen peroxide using the catalyst described in this invention are as follows:

[0027] (1) Disperse 10.0-30.0 mg of the obtained catalyst in 100 mL of pure aqueous solution. The optimal amount of catalyst used is 20.0 mg.

[0028] (2) Stir the suspension for 30 min in the dark to establish adsorption-desorption equilibrium and ensure sufficient dispersion of the catalyst between the catalyst and the aqueous solution;

[0029] (3) After stirring, turn on the light and ultrasonic vibration, and take about 0.5 mL of supernatant every 20 min according to the predetermined time;

[0030] (4) The concentration of hydrogen peroxide was determined by the iodine method. The supernatant from step (3) was reacted with 0.5 mL of KI solution and 2 mL of (NH4)6Mo7O2 solution. 24 ·The 4H2O solution is thoroughly mixed;

[0031] (5) Analyze the absorbance of the 3 mL mixture from step (4) at a wavelength of 352 nm using a UV-vis spectrophotometer.

[0032] According to the present invention, the concentration of the KI solution in step (4) is 0.01M, and (NH4)6Mo7O 24 The concentration of the 4H2O solution is 0.001M.

[0033] The beneficial effects of this invention are:

[0034] This invention provides a catalyst for the successful doping of transition metal Ni to introduce oxygen vacancies and elemental bismuth, and its application. The catalyst has the following advantages:

[0035] 1. A catalyst was synthesized in one step using a solvothermal method. By changing the reaction solvent and adding a nickel source, the morphology and performance of the catalyst were altered. Since the doping of transition metals introduces impurity energy levels that affect the optical properties of the material, increasing the absorption range of visible light, it can also become an active site for the reaction.

[0036] 2. Doping also causes lattice distortion, generating oxygen vacancies and disrupting Bi-O bonding, which facilitates the formation of an internal electric field, increases the catalyst's polarization effect, and enhances hydrogen peroxide production under the combined action of piezoelectricity and light. Simultaneously, free Bi... 3+ In-situ reduction to elemental bismuth promotes the separation of electrons and holes and prolongs the lifetime of charge carriers.

[0037] 3. The purpose of this invention is to oxidize and reduce pure water to hydrogen peroxide without adding any sacrificial agents, and to monitor the yield in real time using a UV-Vis spectrophotometer. Experimental results show that the synergistic effect of piezoelectric light is better than that of light irradiation alone or piezoelectric light alone. The optimal performance is a hydrogen peroxide yield of 2851.65 μmol∙g under piezoelectric light for 100 minutes. -1 ·L -1 A slight decrease in yield over time is normal, as the liquid-phase reaction is unstable.

[0038] The present invention has a simple operation process, low cost, low energy consumption, uses environmentally friendly materials, and produces a considerable amount of hydrogen peroxide. Attached Figure Description

[0039] Figure 1The images show a comparison of the powder XRD patterns of BiOCl catalysts doped with nickel (transition metal) and the blank control group BiOCl. (a) is the powder XRD pattern of the catalyst prepared with ethylene glycol as the reaction solvent and 8% nickel doping; (b) is the powder XRD pattern of the catalyst prepared with pure water without any doping. The vertical lines represent the standard cards of BiOCl. The diffraction patterns of the synthesized samples are the phase characteristic spectra analysis diagrams of the compounds. Each compound has a unique diffraction pattern, which is used for qualitative analysis of the synthesized samples.

[0040] Figure 2 This is a comparison of the surface defect distribution of BiOCl catalysts doped with transition metal nickel and the blank control group BiOCl. (a) Surface defect distribution of the catalyst prepared with ethylene glycol as the reaction solvent and nickel doping content of 8%; (b) Surface defect distribution of the catalyst prepared with pure water without any doping.

[0041] Figure 3 Comparison of scanning electron microscope (SEM) images of the catalyst (a) prepared with nickel doping as a reaction solvent for ethylene glycol and the sample synthesized in pure water (b).

[0042] Figure 4 High-resolution transmission electron microscopy (TEM) image of the catalyst prepared with nickel doping and ethylene glycol as the reaction solvent.

[0043] Figure 5 The hydrogen peroxide yield of the catalyst prepared with nickel doping as the reaction solvent for ethylene glycol is compared under different reaction conditions. The amount of catalyst used is 20.0 mg. The change in hydrogen peroxide yield was monitored in real time every 20 min using a UV-Vis spectrophotometer and other equipment: (a) Hydrogen peroxide yield of the modified catalyst under 300W (λ≥420nm) xenon lamp irradiation; (b) Hydrogen peroxide yield of the modified catalyst under 100W piezoelectric catalysis; (c) Hydrogen peroxide yield of the modified catalyst under piezoelectric-photosynergistic effect. Detailed Implementation

[0044] The present invention will be described in more detail below with specific examples. The following are merely illustrative and explanatory notes and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above-mentioned content of the present invention are covered within the scope of protection of the present invention.

[0045] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0046] According to the present invention, the ethylene glycol in steps (1) and (2) is replaced with deionized water, and step (3) is omitted to synthesize a blank control catalyst with the catalyst.

[0047] Example 1:

[0048] a: Accurately weigh 1.455 g (3 mmol) of Bi(NO3)3·5H2O and dissolve it in 30 mL of ethylene glycol. Stir and label this solution A. Then, dissolve 0.225 g (3 mmol) of KCl in 20 mL of ethylene glycol and stir to dissolve. Label this solution B. Add solution B to solution A and stir to form a homogeneous mixture C. Add NiCl2·6H2O to mixture C at a mass equal to 8% of the mass of Bi(NO3)3·5H2O, i.e., 0.1164 g of NiCl2·6H2O, and stir to dissolve completely.

[0049] b: The obtained homogeneous solution was transferred to a 100 mL PTFE high-pressure reactor and placed in an oven, heated to 160 °C and reacted for 12 h; finally, it was cooled to room temperature, and the sample was washed, dried and ground to obtain a bismuth-based substrate catalyst BiOCl containing nickel doping.

[0050] c: Accurately weigh 20.0 mg of the above catalyst and uniformly disperse it in 100 mL of pure water. First, stir the suspension for 30 min in the dark to establish adsorption-desorption equilibrium and ensure that the catalyst is fully dispersed in the aqueous solution.

[0051] d: After reaching adsorption-desorption equilibrium, the light-only experiment involves placing a beaker containing the catalyst aqueous solution on a stirrer, with a 300W xenon lamp above as the visible light source (xenon lamp, λ≥420nm, PLS-SXE300, Perfect Light, Beijing Bofeilai). 0.5mL of the supernatant is taken every 20min at predetermined time intervals.

[0052] e: To determine the concentration of hydrogen peroxide using the iodine method, the supernatant from step d is reacted with 0.5 mL of 0.01 M KI solution and 2 mL of (NH4)6Mo7O. 24 The 0.001M 4H₂O solution was thoroughly mixed, and the mixture was placed in a 5mL centrifuge tube and shaken vigorously for 3 minutes. The absorbance of the 3mL mixture was analyzed at a wavelength of 352nm using a UV-Vis spectrophotometer, thus enabling real-time monitoring of the reaction yield.

[0053] Example 1: Under light-only conditions, the hydrogen peroxide production was only 218.83 μmol·g over 120 minutes. -1 ·L -1 .

[0054] Example 2:

[0055] a: Accurately weigh 1.455 g (3 mmol) of Bi(NO3)3·5H2O and dissolve it in 30 mL of ethylene glycol. Stir and label this solution A. Then, dissolve 0.225 g (3 mmol) of KCl in 20 mL of ethylene glycol and stir to dissolve. Label this solution B. Add solution B to solution A and stir to form a homogeneous mixture C. Add NiCl2·6H2O to mixture C at a mass equal to 8% of the mass of Bi(NO3)3·5H2O, i.e., 0.1164 g of NiCl2·6H2O, and stir to dissolve completely.

[0056] b: The obtained homogeneous solution was transferred to a 100 mL PTFE high-pressure reactor and placed in an oven, heated to 160 °C and reacted for 12 h; finally, it was cooled to room temperature, and the sample was washed, dried and ground to obtain a bismuth-based substrate catalyst BiOCl containing nickel doping.

[0057] c: Accurately weigh 20.0 mg of the above catalyst and uniformly disperse it in 100 mL of pure water. First, stir the suspension for 30 min in the dark to establish adsorption-desorption equilibrium and ensure that the catalyst is fully dispersed in the aqueous solution.

[0058] d: After reaching adsorption-desorption equilibrium, the piezoelectric experiment was conducted by placing a beaker containing the catalyst aqueous solution in an ultrasonic instrument (100W, 40kHz, KQ2200DB, Kunshan Ultrasonic Instrument Co., Ltd., China). 0.5 mL of the supernatant was collected every 20 minutes at predetermined time intervals.

[0059] e: To determine the concentration of hydrogen peroxide using the iodine method, the supernatant from step d is reacted with 0.5 mL of 0.01 M KI solution and 2 mL of (NH4)6Mo7O. 24 The 0.001M 4H₂O solution was thoroughly mixed, and the mixture was placed in a 5mL centrifuge tube and shaken vigorously for 3 minutes. The absorbance of the 3mL mixture was analyzed at a wavelength of 352nm using a UV-Vis spectrophotometer, thus enabling real-time monitoring of the reaction yield.

[0060] Example 2: Under piezoelectric conditions only, the hydrogen peroxide production within 120 min was 388.34 μmol·g. -1 ·L -1 .

[0061] Example 3:

[0062] a: Accurately weigh 1.455 g (3 mmol) of Bi(NO3)3·5H2O and dissolve it in 30 mL of ethylene glycol. Stir and label this solution A. Then, dissolve 0.225 g (3 mmol) of KCl in 20 mL of ethylene glycol and stir to dissolve. Label this solution B. Add solution B to solution A and stir to form a homogeneous mixture C. Add NiCl2·6H2O to mixture C at a mass equal to 8% of the mass of Bi(NO3)3·5H2O, i.e., 0.1164 g of NiCl2·6H2O, and stir to dissolve completely.

[0063] b: The obtained homogeneous solution was transferred to a 100 mL PTFE high-pressure reactor and placed in an oven, heated to 160 °C and reacted for 12 h; finally, it was cooled to room temperature, and the sample was washed, dried and ground to obtain a bismuth-based substrate catalyst BiOCl containing nickel doping.

[0064] c: Accurately weigh 20.0 mg of the above catalyst and uniformly disperse it in 100 mL of pure water. First, stir the suspension for 30 min in the dark to establish adsorption-desorption equilibrium and ensure that the catalyst is fully dispersed in the aqueous solution.

[0065] d: After adsorption-desorption equilibrium is reached, the piezoelectric-photonic synergistic experiment involves placing a beaker containing an aqueous catalyst solution in an ultrasonic apparatus under xenon lamp illumination. At predetermined time intervals, 0.5 mL of the supernatant is collected every 20 minutes.

[0066] e: To determine the concentration of hydrogen peroxide using the iodine method, the supernatant from step d is reacted with 0.5 mL of 0.01 M KI solution and 2 mL of (NH4)6Mo7O. 24 The 0.001M 4H₂O solution was thoroughly mixed, and the mixture was placed in a 5mL centrifuge tube and shaken vigorously for 3 minutes. The absorbance of the 3mL mixture was analyzed at a wavelength of 352nm using a UV-Vis spectrophotometer, thus enabling real-time monitoring of the reaction yield.

[0067] In Example 3, the yield of hydrogen peroxide fluctuated within 120 min under piezoelectric and photoelectric conditions, with the optimal yield being 2851.65 μmol·g at 100 min. -1 ·L -1 .

[0068] The three examples of catalysts were synthesized using the same steps and belonged to the same sample. The difference lay in the change of catalytic reaction conditions, which was used to explore the effect of piezoelectric-photosynergistic effect on catalyst performance.

[0069] Figure 1The images show a comparison of the powder XRD patterns of BiOCl catalysts doped with transition metal nickel and the blank control group BiOCl. (a) is the XRD pattern of the BiOCl catalyst powder prepared with a transition metal Ni content of 8%; (b) is the XRD pattern of the pure BiOCl catalyst powder. The vertical lines represent the standard cards of BiOCl.

[0070] from Figure 1 It can be seen that the main peak of the blank group of BOCl (using pure water as solvent and without adding nickel source) corresponds to the standard card. The diffraction peaks of the nickel-doped BiOCl of this invention basically correspond one-to-one with the standard card, indicating that nickel doping does not affect the crystal structure of BiOCl.

[0071] Figure 2 This is a comparison of the surface defect distribution of BiOCl catalysts doped with transition metal nickel and the blank control group BiOCl. (a) Surface defect distribution of BiOCl catalyst powder prepared with transition metal Ni doping; (b) Surface defect distribution of pure BiOCl catalyst powder.

[0072] from Figure 2 It can be seen that the surface defect distribution is an oxygen vacancy distribution. A distinct symmetrical signal is displayed at EPR=2.003, representing the characteristic signal of unpaired electrons trapped in oxygen vacancies. The intensity of this signal is directly related to the oxygen vacancy concentration and shows a consistent trend. The oxygen vacancy concentration in nickel-doped BiOCl is greater than that in BiOCl synthesized from pure water.

[0073] Figure 3 (a) shows the BiOCl catalyst prepared with a transition metal Ni content of 8%, and (b) shows the scanning electron microscope (SEM) comparison of the pure BiOCl catalyst.

[0074] from Figure 3 The morphology and structure of the synthesized samples can be seen. The BiOCl synthesized in pure water is a nanosheet structure with a length range of approximately 3000-4000 nm and a thickness range of 150-200 nm; the nickel-doped BiOCl is a nanosphere with a diameter range of 800-840 nm.

[0075] Figure 4 High-resolution transmission electron microscopy (TEM) image of BiOCl catalyst prepared by Ni doping with transition metal.

[0076] from Figure 4 The interplanar spacings of 0.2704 and 0.2766 nm can be observed, which belong to the (110) crystal plane of BiOCl; the interplanar spacings of 0.319 and 0.3226 nm belong to the (012) crystal plane of BiO nanoparticles, which confirms the production of a small amount of bismuth.

[0077] Figure 5 The graph shows a comparison of hydrogen peroxide production under different reaction conditions for a nickel-doped catalyst used as a reaction solvent for ethylene glycol. The catalyst dosage was 20.0 mg, and the hydrogen peroxide production was monitored every 20 minutes using a UV-Vis spectrophotometer and other equipment. (a) Hydrogen peroxide production of the modified catalyst under 300W (λ≥420nm) xenon lamp irradiation; (b) Hydrogen peroxide production of the modified catalyst under 100W piezoelectric catalysis; (c) Hydrogen peroxide production of the modified catalyst under piezoelectric-photosynergistic effects. The blank control group produced almost no hydrogen peroxide within 120 minutes, and the results are negligible. The graph also compares the results of the nickel-doped BiOCl catalyst.

[0078] from Figure 5 It can be seen that, under the same catalyst mass, different reaction conditions affect the yield of hydrogen peroxide, and the piezoelectric-photoelectric synergistic effect achieves a "1+1>2" effect.

[0079] The blank control group is a BiOCl sample synthesized in pure water without any transition metals. The chemical characterization XRD, EPR results and SEM images are compared with this sample. The final performance is a comparison of the hydrogen peroxide production of nickel-doped BiOCl sample under different reaction conditions.

[0080] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A layered bismuth-based catalyst BiOCl-Ni containing oxygen vacancies and metal doping, characterized in that, The catalyst is composed of nano-layered BiOCl microspheres doped with transition metal nickel, with oxygen vacancies and some bismuth metal (Bi) uniformly distributed on the surface of the microspheres. 0 Nanoparticles.

2. The layered bismuth-based catalyst BiOCl-Ni containing oxygen vacancies and metal doping according to claim 1, characterized in that, The diameter of the microspheres is between 800-840 nm.

3. The method for preparing a layered bismuth-based catalyst BiOCl-Ni containing oxygen vacancies and metal doping as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Dissolve the bismuth source in a certain amount of ethylene glycol, stir, and label it as solution A; dissolve the chlorine source in ethylene glycol, stir, and label it as solution B; slowly add solution B to solution A, stir to make it fully mixed to form a mixture C; (2) Add the nickel source to the mixture C and stir again to obtain a mixed solution; (3) Transfer the mixed solution from step (2) into a high-pressure reactor and place it in a vacuum oven for hydrothermal reaction; (4) After the hydrothermal reaction, the product is cooled to room temperature, washed several times with a mixed solvent of deionized water and ethanol in a volume ratio of 4-24:1-6, and dried in an oven to obtain the nickel-doped BiOCl catalyst.

4. The method according to claim 3, characterized in that, The bismuth source is selected from one or more of bismuth nitrate pentahydrate, bismuth oxide, and bismuth chloride; the chlorine source is one or more of potassium chloride, sodium chloride, or hexadecyltrimethylammonium chloride; and the nickel source is one or more of nickel chloride hexahydrate and nickel nitrate. The optimal bismuth source, chlorine source, and nickel source are bismuth nitrate pentahydrate, potassium chloride, and nickel chloride hexahydrate, respectively.

5. The method according to claim 3, characterized in that, The amount of bismuth source and chlorine source added makes the molar ratio of bismuth to chlorine 1:1, and the amount of nickel source added is 8% of the mass of bismuth source.

6. The method according to claim 3, characterized in that, In step (3), the heating temperature of the hydrothermal method is 150-200℃ and the heating time is 8-15h; preferably 160℃ and 12h.

7. The method according to claim 3, characterized in that, In steps (1) and (2), the stirring time is 20-40 min, with an optimal time of 30 min; the stirring speed is 200-600 r / min, with an optimal time of 500 r / min. In step (4), the washing method is to discard the supernatant in the heated reaction vessel and keep the precipitate. The precipitate is washed five times with a mixture of deionized water and anhydrous ethanol at the above-mentioned optimal speed of 500 r / min. Then, it is centrifuged at a speed of 5000-8000 r / min and the centrifuged material is collected. The optimal speed for centrifugation is 7500 r / min. In step (4), the drying temperature is 50-80℃ and the drying time is 8-15h. The optimal heating temperature and heating time are 70℃ and 12h, respectively.

8. The application of the oxygen-vacancy- and metal-doped layered bismuth-based catalyst BiOCl-Ni as described in claim 1 or 2, for the catalytic production of hydrogen peroxide in pure water.

9. The application according to claim 8, wherein the catalyst is subjected to the combined action of visible light irradiation and ultrasound, the light source being a 300W xenon lamp with a main wavelength of λ≥420nm, and the ultrasound using an ultrasonic instrument with a frequency of 40kHz and a power of 40~300W.

10. In the application according to claim 8, the ultrasonic instrument is selected with a power of 100W.

Images