Hydrogen peroxide modified bismuth-based composite photocatalytic material, and preparation method and application thereof

Abstract

The application discloses a hydrogen peroxide modified bismuth-based composite photocatalytic material and a preparation method and application thereof, and belongs to the technical field of inorganic material modification. The hydrogen peroxide modified bismuth-based composite photocatalytic material is prepared from Bi2WO6, H2O2-Bi2O2CO3, polyvinylpyrrolidone, citric acid, a silane coupling agent and thiourea, H2O2-Bi2O2CO3 is loaded on the surface of modified Bi2WO6 to form a composite structure in close contact, and the H2O2-Bi2O2CO3 is prepared from bismuth nitrate pentahydrate, sodium carbonate and the like through hydrothermal reaction and hydrogen peroxide oxidation. The hydrogen peroxide modified bismuth-based composite photocatalytic material prepared by the application can build a Z-type heterojunction to realize efficient separation of carriers, the sulfur-hydrogen bond has the functions of reaction gas activation and local proton supply, and the silicon-oxygen-tungsten covalent bond strengthens the interface combination, so that the photocatalytic reduction of carbon dioxide and nitrogen can be realized synchronously, the catalytic performance is excellent, and the cycle stability is good.

Description

Technical Field

[0001] This invention relates to the field of inorganic material modification technology, specifically to a hydrogen peroxide-modified bismuth-based composite photocatalytic material, its preparation method, and its application. Background Technology

[0002] Ammonia is a core raw material in the chemical and agricultural sectors, and also an ideal hydrogen carrier, with a global annual production exceeding 200 million tons. Currently, industrial ammonia synthesis mainly relies on the Haber-Bosch process, which requires harsh conditions of high temperature and pressure, resulting in high energy consumption and significant carbon dioxide emissions, contradicting the demands of green development. Therefore, developing solar-driven photocatalytic technology at ambient temperature and pressure to achieve nitrogen reduction for ammonia production and carbon dioxide reduction for resource recovery has become a research hotspot in the energy and environmental fields. Bismuth-based aspherical semiconductor materials, such as bismuth tungstate and bismuth oxycarbonate, have become candidate materials for photocatalysis due to their suitable band structure, visible light response characteristics, non-toxicity, and good chemical stability.

[0003] However, single bismuth-based materials still have many core defects: First, the recombination rate of photogenerated carriers is high, resulting in low quantum efficiency. Pure-phase bismuth tungstate and bismuth oxycarbonate have short lifetimes of photogenerated electron-hole pairs, with most carriers recombinating before migrating to surface active sites. Second, the adsorption and activation capacity of reactive gases is weak, and the material surface lacks effective active sites, making it difficult to polarize and break high-energy chemical bonds, resulting in low catalytic activity. Third, the catalytic reaction kinetics are sluggish. In traditional modified materials, gas activation sites and proton supply sites are spatially separated, leading to high proton transfer resistance and high reaction energy barriers during hydrogenation. Fourth, the interfacial bonding of composite modified materials is weak. The two phases are only mixed physically, making phase separation and structural collapse prone to occur during catalytic cycling, resulting in poor cycle stability. Fifth, the material has a single function, making it difficult to simultaneously achieve dual-function catalysis for nitrogen reduction and carbon dioxide reduction, thus failing to meet the needs of multi-scenario collaborative governance.

[0004] To address the aforementioned issues, existing modification methods mostly focus on single-element doping or simple physical compositing, failing to simultaneously achieve multiple objectives such as efficient carrier separation, strong adsorption and activation of reactive gases, spatial matching between proton sources and active sites, stable interfacial bonding, and multifunctional synergy.

[0005] Therefore, how to achieve the controllable preparation of highly efficient bismuth-based composite photocatalytic materials with multi-component synergistic modification has become a technical challenge that urgently needs to be overcome by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a hydrogen peroxide-modified bismuth-based composite photocatalytic material, its preparation method, and its application, so as to overcome the problem that existing bismuth-based photocatalytic materials are difficult to simultaneously achieve efficient gas activation, tight heterogeneous interface construction, and bifunctional photocatalytic conversion.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material, comprising the following steps: Polyvinylpyrrolidone and citric acid were added to the alcohol solution and stirred. Then, silane coupling agent and thiourea were added, and stirring and heating were continued to obtain the reaction base solution. Bi2WO6 was added to the reaction substrate, sonicated, stirred, and heated to obtain modified Bi2WO6. Modified Bi2WO6 was added to water and stirred. Then H2O2-Bi2O2CO3 was added, and stirring and heating were continued to obtain hydrogen peroxide modified bismuth-based composite photocatalytic material. H2O2-Bi2O2CO3 is prepared through the following steps: Bismuth nitrate pentahydrate was added to the acid solution and stirred to obtain reaction solution A. Sodium carbonate and hexadecyltrimethylammonium bromide were added to water and stirred to obtain reaction solution B. Reaction solution B was added to reaction solution A, stirred, and heated to obtain Bi2O2CO3. Bi2O2CO3 was added to water, stirred, and then hydrogen peroxide was added. Stirring and heating were continued to obtain H2O2-Bi2O2CO3.

[0008] A further improvement of this invention is that Bi2WO6 is prepared through the following steps: Sodium tungstate, ammonium fluoride and urea were added to the composite alcohol solution and stirred to obtain reaction solution I; Hexadecyltrimethylammonium bromide and ascorbic acid were added to the composite alcohol solution and stirred to obtain reaction solution II; Add reaction solution II to reaction solution I, stir, and heat to obtain Bi2WO6.

[0009] A further improvement of this invention is that the composite alcohol solution is composed of ethylene glycol and water in a mass ratio of 7:3; and the heating temperature for preparing Bi2WO6 is 150~190℃.

[0010] A further improvement of the present invention is that, in the step of preparing H2O2-Bi2O2CO3, the acid solution is a nitric acid solution with a concentration of 1.5~2.5 mol / L; and the heating temperature for preparing Bi2O2CO3 is 120-140℃.

[0011] A further improvement of the present invention is that, in the step of preparing the reaction base liquid, the alcohol liquid is composed of anhydrous ethanol and water in a mass ratio of 8:2; and in the step of preparing modified Bi2WO6, the heating temperature is 160~180℃.

[0012] The present invention also provides a hydrogen peroxide-modified bismuth-based composite photocatalyst material, which is prepared by the preparation method of hydrogen peroxide-modified bismuth-based composite photocatalyst material described above. The hydrogen peroxide-modified bismuth-based composite photocatalyst material is prepared from Bi2WO6, H2O2-Bi2O2CO3, polyvinylpyrrolidone, citric acid, silane coupling agent and thiourea; the H2O2-Bi2O2CO3 is loaded on the surface of modified Bi2WO6, and the two form a closely contacted composite structure.

[0013] A further improvement of the present invention is that, by weight, the hydrogen peroxide modified bismuth-based composite photocatalytic material comprises the following components: 1.5-2.5 parts Bi2WO6, 0.22-0.42 parts H2O2-Bi2O2CO3, 0.6-0.9 parts polyvinylpyrrolidone, 0.05-0.15 parts citric acid, 0.1 parts silane coupling agent, and 0.3-0.6 parts thiourea.

[0014] A further improvement of the present invention is that the H2O2-Bi2O2CO3 is prepared from sodium carbonate, bismuth nitrate pentahydrate, hexadecyltrimethylammonium bromide and hydrogen peroxide, and the mass ratio of sodium carbonate: bismuth nitrate pentahydrate: hexadecyltrimethylammonium bromide: hydrogen peroxide is 3~4.5:6~9:0.5~0.9:1.2.

[0015] A further improvement of the present invention is that the Bi2WO6 is prepared from sodium tungstate, bismuth nitrate pentahydrate, ammonium fluoride, urea, hexadecyltrimethylammonium bromide and ascorbic acid, and the mass ratio of sodium tungstate: bismuth nitrate pentahydrate: ammonium fluoride: urea: hexadecyltrimethylammonium bromide: ascorbic acid is 1.5-2.5: 2-4: 0.6-0.9: 1-1.4: 0.4-0.8: 0.25-0.5.

[0016] The present invention also provides an application of the hydrogen peroxide-modified bismuth-based composite photocatalytic material as described above in the photocatalytic reduction of carbon dioxide and the photocatalytic reduction of nitrogen.

[0017] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The preparation method of hydrogen peroxide-modified bismuth-based composite photocatalytic material provided by this invention achieves simultaneous high-efficiency gas activation, tight heterogeneous interface construction, and bifunctional photocatalytic conversion under mild conditions through a multi-step synergistic process. Specifically, through the synergistic modification of thiourea and hydrogen peroxide, a multifunctional active layer rich in thiol, hydroxyl, and carboxyl groups is constructed on the material surface. The sulfur atoms in the thiol groups polarize the N2 molecules through n→π electron donation, while the sulfur-hydrogen bonds of the thiol groups undergo photo-induced heterolytic cleavage under light irradiation, releasing protons in situ at the activation sites. This achieves an integrated design of N2 activation and in-situ proton donation, eliminating the diffusion resistance of protons from the bulk solution to the active sites, reducing the hydrogenation reaction energy barrier, and overcoming the defects of weak gas adsorption activation ability and slow reaction kinetics in existing materials. By condensing silane coupling agent with hydroxyl groups on the surfaces of the two phases to form Si-OW covalent bonds, chemical bonding of Bi2WO6 and H2O2-Bi2O2CO3 interface is achieved, ensuring that the two form a stable composite structure with close contact, overcoming the defects of weak interfacial bonding and easy phase separation of existing physical composite materials. A Z-shaped heterojunction was constructed via hydrothermal synthesis, achieving efficient spatial separation of photogenerated carriers under the drive of a built-in electric field. The sufficiently negative conduction band position of H2O2-Bi2O2CO3 enables simultaneous CO2 and N2 reduction. Combined with the broad-spectrum adsorption and activation capabilities of the material surface for both gas molecules, the single material exhibits excellent photocatalytic reduction activity for both N2 and CO2 at room temperature and pressure, realizing bifunctional photocatalytic conversion.

[0018] In the hydrogen peroxide-modified bismuth-based composite photocatalytic material prepared by this invention, H2O2-Bi2O2CO3 is tightly loaded on the surface of modified Bi2WO6, forming a structurally stable composite structure, which ensures excellent photochemical stability and recyclability. The material surface is rich in multifunctional groups such as hydroxyl, carboxyl and thiol groups, which endow it with broad-spectrum adsorption and activation capabilities for N2 and CO2. Combined with the high carrier separation efficiency of the Z-type heterojunction, a single material can achieve bifunctional photocatalytic conversion of multiple substrates. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a simplified diagram illustrating the preparation method of the hydrogen peroxide-modified bismuth-based composite photocatalyst material of the present invention. Figure 2 The figures show the CO product test results of the hydrogen peroxide-modified bismuth-based composite photocatalysts prepared in the examples and comparative examples. Figure 3The graph shows the NH3 product test results of the hydrogen peroxide-modified bismuth-based composite photocatalyst materials prepared in the examples and comparative examples. Figure 4 The image shows the XRD results of the H2O2-Bi2O2CO3 prepared in Example 2. Figure 5 The image shows the SEM test results of the hydrogen peroxide-modified bismuth-based composite photocatalyst material prepared in Example 2. Detailed Implementation

[0021] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0022] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0023] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0024] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0025] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0026] The present invention provides a method for preparing a battery material based on carbon fiber composite, comprising the following steps: The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0027] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art, unless otherwise stated. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to weight parts, and "ratio" refers to weight proportion, wherein the composite alcohol solution is composed of the following mass ratio of raw materials: ethylene glycol:water = 7:3, and the alcohol solution includes the following mass ratio of materials: anhydrous ethanol:water = 8:2.

[0028] See Figure 1 This invention provides a method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material, comprising the following steps: Step 1: Preparation of the reaction base solution. Polyvinylpyrrolidone (PVP) and citric acid are added to an alcohol solution and stirred until they are fully dissolved and uniformly dispersed. A silane coupling agent and thiourea are added to the resulting mixture, and stirring continues to ensure sufficient contact between the silane coupling agent and thiourea and all components in the system. After stirring, the system is heated to obtain the reaction base solution. PPVP and citric acid act as dispersants and morphology modifiers, aiding in the dispersion of Bi2WO6 particles during subsequent modification. The silane coupling agent contains hydrolyzable silicon functional groups, and the thiourea molecule contains SH bonds; both coexist in the reaction base solution, providing the necessary chemical environment for the surface modification of Bi2WO6. The heating process promotes pre-reaction and homogenization among the components, resulting in a stable dispersion system in the reaction base solution.

[0029] Step 2: Preparation of Modified Bi2WO6. Bi2WO6 was added to the reaction solution obtained in Step 1 and first subjected to ultrasonic treatment to ensure thorough dispersion of Bi2WO6 particles and reduce particle agglomeration. After ultrasonication, the mixture was stirred to ensure full contact between the surface of the Bi2WO6 particles and the polyvinylpyrrolidone, citric acid, silane coupling agent, and thiourea in the reaction solution. After stirring, the system was heated. Under heating conditions, the silane coupling agent chemically bonded to the surface of Bi2WO6, and thiourea molecules modified the surface of Bi2WO6 through their functional groups, resulting in modified Bi2WO6. This step introduced silicon-containing and sulfur-containing functional groups into the surface of Bi2WO6, altering its surface properties and providing favorable interfacial bonding conditions for subsequent composite formation with H2O2-Bi2O2CO3.

[0030] Step 3: Preparation of hydrogen peroxide-modified bismuth-based composite photocatalyst. The modified Bi₂WO₆ obtained in Step 2 was added to water and stirred to uniformly disperse it in the aqueous phase, resulting in a modified Bi₂WO₆ suspension. H₂O₂-Bi₂O₂CO₃ was added to this suspension, and stirring continued to ensure sufficient contact and uniform mixing between the H₂O₂-Bi₂O₂CO₃ particles and the modified Bi₂WO₆ particles. After stirring, the system was heated. Under heating conditions, the silicon functional groups on the surface of the modified Bi₂WO₆ interacted with the surface of the H₂O₂-Bi₂O₂CO₃, forming a tight interfacial bond. After cooling, separation, washing, and drying, the hydrogen peroxide-modified bismuth-based composite photocatalyst was obtained. In this composite photocatalyst, H₂O₂-Bi₂O₂CO₃ is loaded on the surface of the modified Bi₂WO₆, forming a tightly contacted composite structure, which is beneficial for the effective separation and transport of photogenerated carriers at the two-phase interface.

[0031] In this embodiment, H2O2-Bi2O2CO3 is prepared through the following steps: S11. Add bismuth nitrate pentahydrate to the acid solution and stir until the bismuth nitrate pentahydrate is fully dissolved to obtain reaction solution A; add sodium carbonate and hexadecyltrimethylammonium bromide to water and stir until the sodium carbonate and hexadecyltrimethylammonium bromide are fully dissolved and mixed evenly to obtain reaction solution B. The acid solution is a nitric acid solution, providing a stable acidic environment for bismuth ions; hexadecyltrimethylammonium bromide acts as a surfactant, controlling the morphology of the products in subsequent reactions.

[0032] S12. Add reaction solution B to reaction solution A, stir to ensure thorough mixing and reaction. After stirring, heat the system. Under heating conditions, bismuth ions react with carbonate ions to form bismuth oxycarbonate (Bi₂O₂CO₃). After the reaction is complete, allow it to cool naturally to room temperature, wash, and dry to obtain Bi₂O₂CO₃.

[0033] S13. Add the Bi2O2CO3 obtained in step S12 to water and stir to disperse it evenly. Add hydrogen peroxide (H2O2) to the dispersion and continue stirring to ensure sufficient contact between the hydrogen peroxide and Bi2O2CO3. After stirring, heat the system. Under heating conditions, hydrogen peroxide oxidizes and modifies Bi2O2CO3 to obtain H2O2-Bi2O2CO3. After modification with hydrogen peroxide, the surface chemical state of Bi2O2CO3 changes, which is beneficial to improving its photocatalytic activity and interfacial compatibility with modified Bi2WO6.

[0034] The preparation method provided in this embodiment involves first constructing a reaction substrate containing polyvinylpyrrolidone, citric acid, a silane coupling agent, and thiourea to modify the surface of Bi2WO6. Then, it is composited with H2O2-Bi2O2CO3 in an aqueous phase under heating. This allows H2O2-Bi2O2CO3 to be effectively loaded onto the modified Bi2WO6 surface, forming a tightly contacted composite structure. This composite structure helps reduce the recombination probability of photogenerated electron-hole pairs and improves the material's adsorption and activation ability for reactant gases, thereby overcoming the problems of high photogenerated carrier recombination rate, weak interfacial bonding, and slow catalytic reaction kinetics inherent in single bismuth-based materials.

[0035] In some embodiments of this application, Bi2WO6 is prepared by the following steps: S21. Add sodium tungstate, ammonium fluoride, and urea to the composite alcohol solution, stir to fully dissolve and mix the components, and obtain reaction solution I. Sodium tungstate provides the tungsten source, ammonium fluoride acts as a mineralizing agent to regulate crystal facets, and urea decomposes under heating conditions to provide an alkaline environment. The composite alcohol solution is composed of ethylene glycol and water in a mass ratio of 7:3. The ethylene glycol-water binary solvent system helps to regulate the morphology and crystal form of the product.

[0036] S22. Add hexadecyltrimethylammonium bromide and ascorbic acid to the composite alcohol solution and stir until both are fully dissolved to obtain reaction solution II. Hexadecyltrimethylammonium bromide acts as a surfactant, selectively adsorbing onto specific crystal faces to regulate crystal growth direction; ascorbic acid acts as a reducing agent, protecting the reaction system. The composite alcohol solution is also composed of ethylene glycol and water in a mass ratio of 7:3.

[0037] S23. Add reaction solution II to reaction solution I and stir to ensure thorough mixing. After stirring, heat the system to a temperature of 150-190°C. Under heating conditions, bismuth ions (provided by bismuth nitrate pentahydrate added to the system) react with tungstate ions to generate bismuth tungstate (Bi2WO6). After the reaction is complete, allow it to cool naturally to room temperature, wash, and dry to obtain Bi2WO6. Bismuth nitrate pentahydrate can be added together with sodium tungstate in step S21, or added in an appropriate step according to the actual process. The Bi2WO6 prepared using this embodiment exhibits good crystallinity and morphological regularity, providing a good substrate material for subsequent surface modification and composites.

[0038] In some embodiments of this application, in the step of preparing H₂O₂-Bi₂O₂CO₃, the acid solution is a nitric acid solution, and the concentration of the nitric acid solution can be selected from 1.5 to 2.5 mol / L. Using a nitric acid solution within this concentration range provides a suitable acidic environment for bismuth ions, allowing bismuth nitrate pentahydrate to fully dissolve and remain stable, while also facilitating the subsequent reaction with carbonate ions to generate the Bi₂O₂CO₃ precursor. During the preparation of Bi₂O₂CO₃, the heating temperature can be selected from 120 to 140°C. Within this temperature range, the reaction system has an appropriate reaction rate, which is beneficial for obtaining a Bi₂O₂CO₃ product with good crystallinity.

[0039] In some embodiments of this application, in the step of preparing the reaction base solution, the alcohol solution is composed of anhydrous ethanol and water in a mass ratio of 8:2. This ethanol-water binary solvent system can effectively dissolve polyvinylpyrrolidone and citric acid, and provides a suitable moisture environment for the dispersion and hydrolysis of the silane coupling agent. In the step of preparing modified Bi2WO6, the heating temperature can be selected as 160~180℃. Within this temperature range, the silane coupling agent can effectively form chemical bonds with the Bi2WO6 surface, while thiourea molecules can be fully modified on the Bi2WO6 surface, thereby obtaining a good modification effect.

[0040] Example 1 A hydrogen peroxide-modified bismuth-based composite photocatalyst material, wherein the hydrogen peroxide-modified bismuth-based composite photocatalyst material comprises the following materials in parts by weight: 1.5 parts Bi2WO6, 0.22 parts H2O2-Bi2O2CO3, 0.6 parts PVP, 0.05 parts citric acid, 0.1 parts silane coupling agent, and 0.3 parts thiourea; A method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material includes the following steps: Preparation of H2O2-Bi2O2CO3: S11. Weigh 6 parts of bismuth nitrate pentahydrate and add them to 30 parts of acid solution, wherein the acid solution is nitric acid solution with a concentration of 1.5 mol / L. Stir at 500 r / min for 30 min to obtain reaction solution A. Weigh 3 parts of sodium carbonate and 0.5 parts of CTAB and add them to 30 parts of deionized water. Stir at 500 r / min for 30 min to obtain reaction solution B. S12. Add the reaction solution B obtained in step S11 to the reaction solution A obtained in step S11, stir at 500 r / min for 30 min, then heat at 120℃ for 12 h, cool naturally to room temperature, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2O2CO3. S13. Add the Bi2O2CO3 obtained in step S12 to 100 parts of deionized water and stir for 30 minutes at a speed of 500 r / min. Weigh 3 parts of H2O2 and add them to the mixture. Continue stirring at the above speed for 30 minutes and heat at a temperature of 120℃ for 4 hours to obtain H2O2-Bi2O2CO3.

[0041] Preparation of Bi2WO6: S21. Weigh 1.5 parts sodium tungstate, 0.6-0.9 parts ammonium fluoride and 1 part urea and add them to 60 parts composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution I. S22. Weigh 0.4 parts of CTAB and 0.25 parts of ascorbic acid and add them to 20 parts of composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution II. S23. Add reaction solution II obtained in step S22 to reaction solution I obtained in step S21, stir at 500 r / min for 30 min, heat at 150℃ for 12 h, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2WO6. Preparation of hydrogen peroxide-modified bismuth-based composite photocatalytic materials: S31. Weigh 0.6 parts PVP and 0.05 parts citric acid and add them to 50 parts alcohol solution. Stir at 500 r / min for 30 min. Weigh 0.1 parts silane coupling agent and 0.3 parts thiourea and add them to the solution. Continue stirring at the above speed for 30 min. Heat at 80℃ for 30 min to obtain the reaction base solution. S32. Weigh 1.5 parts of Bi2WO6 and add it to the reaction base liquid obtained in step S31. Sonicate at a frequency of 25 kHz for 15 min, stir at a speed of 500 r / min for 60 min, then heat at a temperature of 160℃ for 15 h, wash with deionized water 5 times, and dry at a temperature of 75℃ for 24 h to obtain modified Bi2WO6. S33. Add modified Bi2WO6 to 75 parts of deionized water and stir for 30 min at a speed of 500 r / min. Weigh 0.22 parts of H2O2-Bi2O2CO3 and add it to the mixture. Continue stirring at the above speed for 30 min. Heat at 120℃ for 6 h. Wash the mixture three times each with deionized water and anhydrous ethanol. Dry at 75℃ for 24 h to obtain hydrogen peroxide modified bismuth-based composite photocatalyst material.

[0042] Example 2 A hydrogen peroxide-modified bismuth-based composite photocatalyst material, wherein the hydrogen peroxide-modified bismuth-based composite photocatalyst material comprises the following materials in parts by weight: 62 parts Bi2WO, 0.32 parts H2O2-Bi2O2CO3, 0.75 parts PVP, 0.1 parts citric acid, 0.1 parts silane coupling agent, and 0.45 parts thiourea; A method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material includes the following steps: Preparation of H2O2-Bi2O2CO3: S11. Weigh 7.5 parts of bismuth nitrate pentahydrate and add it to 30 parts of acid solution, wherein the acid solution is nitric acid solution with a concentration of 2 mol / L. Stir at 500 r / min for 30 min to obtain reaction solution A. Weigh 3.8 parts of sodium carbonate and 0.7 parts of CTAB and add them to 30 parts of deionized water. Stir at 500 r / min for 30 min to obtain reaction solution B. S12. Add the reaction solution B obtained in step S11 to the reaction solution A obtained in step S11, stir at 500 r / min for 30 min, then heat at 130℃ for 12 h, cool naturally to room temperature, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2O2CO3. S13. Add the Bi2O2CO3 obtained in step S12 to 100 parts of deionized water and stir for 30 minutes at a speed of 500 r / min. Weigh out 5 parts of H2O2 and add it to the mixture. Continue stirring at the above speed for 30 minutes. Heat at a temperature of 120℃ for 5 hours to obtain H2O2-Bi2O2CO3.

[0043] Preparation of Bi2WO6: S21. Weigh 2 parts sodium tungstate, 0.8 parts ammonium fluoride and 1.2 parts urea and add them to 60 parts composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution I. S22. Weigh 0.6 parts of CTAB and 0.4 parts of ascorbic acid and add them to 20 parts of composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution II. S23. Add reaction solution II obtained in step S22 to reaction solution I obtained in step S21, stir at 500 r / min for 30 min, heat at 170℃ for 12 h, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2WO6. Preparation of hydrogen peroxide-modified bismuth-based composite photocatalytic materials: S31. Weigh 0.75 parts PVP and 0.1 parts citric acid and add them to 50 parts alcohol solution. Stir at 500 r / min for 30 min. Weigh 0.1 parts silane coupling agent and 0.45 parts thiourea and add them to the solution. Continue stirring at the above speed for 30 min. Heat at 80℃ for 30 min to obtain the reaction base solution. S32. Weigh 2 portions of Bi2WO6 and add them to the reaction base liquid obtained in step S31. Sonicate at a frequency of 25 kHz for 15 min, stir at a speed of 500 r / min for 60 min, then heat at a temperature of 170℃ for 15 h, wash with deionized water 5 times, and dry at a temperature of 75℃ for 24 h to obtain modified Bi2WO6. S33. Add modified Bi2WO6 to 75 parts of deionized water and stir for 30 min at a speed of 500 r / min. Weigh 0.32 parts of H2O2-Bi2O2CO3 and add it to the mixture. Continue stirring at the above speed for 30 min. Heat at 130℃ for 6 h. Wash the mixture three times each with deionized water and anhydrous ethanol. Dry at 75℃ for 24 h to obtain hydrogen peroxide modified bismuth-based composite photocatalyst material.

[0044] Example 3 A hydrogen peroxide-modified bismuth-based composite photocatalytic material, wherein the hydrogen peroxide-modified bismuth-based composite photocatalytic material comprises the following materials in parts by weight: 2.5 parts Bi2WO6, 0.42 parts H2O2-Bi2O2CO3, 0.9 parts PVP, 0.15 parts citric acid, 0.1 parts silane coupling agent, and 0.6 parts thiourea; A method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material includes the following steps: Preparation of H2O2-Bi2O2CO3: S11. Weigh 9 parts of bismuth nitrate pentahydrate and add them to 30 parts of acid solution, wherein the acid solution is nitric acid solution with a concentration of 2.5 mol / L. Stir at 500 r / min for 30 min to obtain reaction solution A. Weigh 4.5 parts of sodium carbonate and 0.9 parts of CTAB and add them to 30 parts of deionized water. Stir at 500 r / min for 30 min to obtain reaction solution B. S12. Add the reaction solution B obtained in step S11 to the reaction solution A obtained in step S11, stir at 500 r / min for 30 min, then heat at 140℃ for 12 h, cool naturally to room temperature, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2O2CO3. S13. Add the Bi2O2CO3 obtained in step S12 to 100 parts of deionized water and stir for 30 minutes at a speed of 500 r / min. Weigh out 6 parts of H2O2 and add it to the water. Continue stirring at the speed mentioned above for 30 minutes. Heat at a temperature of 120℃ for 6 hours to obtain H2O2-Bi2O2CO3. Preparation of Bi2WO6: S21. Weigh 2.5 parts sodium tungstate, 0.9 parts ammonium fluoride and 1.4 parts urea and add them to 60 parts composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution I. S22. Weigh 0.8 parts of CTAB and 0.5 parts of ascorbic acid and add them to 20 parts of composite alcohol solution. Stir for 30 minutes at a speed of 500 r / min to obtain reaction solution II. S23. Add reaction solution II obtained in step S22 to reaction solution I obtained in step S21, stir at 500 r / min for 30 min, heat at 190℃ for 12 h, wash with deionized water and anhydrous ethanol three times each, and dry at 75℃ for 24 h to obtain Bi2WO6. Preparation of hydrogen peroxide-modified bismuth-based composite photocatalytic materials: S31. Weigh 0.9 parts PVP and 0.15 parts citric acid and add them to 50 parts alcohol solution. Stir at 500 r / min for 30 min. Weigh 0.1 parts silane coupling agent and 0.6 parts thiourea and add them to the solution. Continue stirring at the above speed for 30 min. Heat at 80℃ for 30 min to obtain the reaction base solution. S32. Weigh 2.5 parts of Bi2WO6 and add it to the reaction base liquid obtained in step S31. Sonicate at a frequency of 25 kHz for 15 min, stir at a speed of 500 r / min for 60 min, then heat at a temperature of 180℃ for 15 h, wash with deionized water 5 times, and dry at a temperature of 75℃ for 24 h to obtain modified Bi2WO6. S33. Add modified Bi2WO6 to 75 parts of deionized water and stir for 30 min at a speed of 500 r / min. Weigh 0.22-0.42 parts of H2O2-Bi2O2CO3 and add it to the mixture. Continue stirring at the above speed for 30 min. Heat at a temperature of 120-140℃ for 6 h. Wash the mixture three times each with deionized water and anhydrous ethanol. Dry the mixture at a temperature of 75℃ for 24 h to obtain hydrogen peroxide modified bismuth-based composite photocatalyst material.

[0045] Comparative example: Comparative Example 1: The difference from Example 2 is that Bi2WO6 was not added; the rest of the steps and conditions are the same as in Example 2.

[0046] Comparative Example 2: The difference from Example 2 is that H2O2-Bi2O2CO3 was not added, but the rest of the steps and conditions are the same as in Example 2.

[0047] Comparative Example 3: Only Bi2WO6 was used, without any modification treatment.

[0048] Comparative Example 4: Only H2O2-Bi2O2CO3 was used, without composite modification.

[0049] Comparative Example 5: Only Bi2O2CO3 was used, without any modification treatment.

[0050] The photocatalytic reduction performance of carbon dioxide and nitrogen gas of the materials prepared in the above examples and comparative examples was tested, and the results are as follows: Figure 2 The CO product test results of the hydrogen peroxide-modified bismuth-based composite photocatalyst materials prepared in the examples and comparative examples show that the CO reduction performance is improved compared with the unmodified Bi2O2CO3. Furthermore, the CO yield in the composite material is significantly higher than that in the comparative example. Figure 3 The N2 reduction performance test results of the hydrogen peroxide-modified bismuth-based composite photocatalytic materials prepared in the examples and comparative examples show that the NH3 yield of the examples using the method of the present invention is higher. These results indicate that the prepared material has high adsorption and activation performance for the photocatalytic reduction of CO2 and N2. Figure 4 The H2O2-Bi2O2CO3 prepared in Example 2 shows that the overall crystallinity of the material is high, and no impurity peaks are observed. Figure 5 The image shows the SEM image of the hydrogen peroxide-modified bismuth-based composite photocatalyst material prepared in Example 2. It can be seen that the surfaces of H2O2-Bi2O2CO3 and Bi2WO6 are in close contact, indicating that the two were successfully composited.

[0051] The hydrogen peroxide-modified bismuth-based composite photocatalyst material prepared in this invention constructs a Z-shaped heterojunction structure through Bi2WO6 and H2O2-Bi2O2CO3. Driven by a built-in electric field, it achieves directional migration of photogenerated carriers, maintaining a strong redox potential while efficiently separating electrons and holes. Through the synergistic effects of hydrogen peroxide oxidation, co-modification with citric acid and thiourea, and bridging with a silane coupling agent, Si-OW covalent bonds are formed to strengthen the interfacial bonding between the two phases. Furthermore, a multifunctional group rich in hydroxyl, carboxyl, and thiol groups is constructed on the material surface. This enhances the adsorption and polarization of N2 molecules through hydrogen bonding and Lewis acid-base interactions, while utilizing the dual function of SH bonds—S atoms capture and activate N2 through n→π electron donation, and SH bond photolysis serves as a local proton source—achieving spatial matching between proton supply and active sites. This effectively solves the core problem of slow reaction kinetics caused by the separation of active sites and proton sources in traditional catalysts. PVP and CTAB synergistically regulate the dispersion state and crystal growth of nanoparticles, significantly improving the specific surface area and active site exposure of the material.

[0052] The hydrogen peroxide-modified bismuth-based composite photocatalytic material prepared in this invention exhibits excellent NH3 generation activity in photocatalytic nitrogen fixation at room temperature and pressure due to the multi-component synergistic modification strategy. Its catalytic performance shows no significant decay after multiple cycles, demonstrating good photochemical stability. Furthermore, the abundant functional groups on the material surface endow it with broad-spectrum adsorption capabilities for N2 and CO2, enabling photocatalytic nitrogen fixation and CO2 resource conversion. Combined with a green and mild hydrothermal preparation process, the material possesses both high catalytic performance and potential for large-scale application.

[0053] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this invention. Their purpose is to clearly illustrate the concept, principle, and application of this invention through specific examples, and is by no means intended to limit the scope of protection of this invention to these specific embodiments. In fact, the true value of this invention lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.

[0054] For those skilled in the art, after thoroughly reading and understanding the technical solution of this invention, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific implementation of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original invention, that is, they can still achieve the core functions and effects of this invention, then these changes should be considered to fall within the scope of protection of the pending claims of this invention.

[0055] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for further improvement and perfection of this invention. Therefore, the scope of protection of this invention should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not depart from the basic principles and core concepts of this invention, they should be considered equivalents of this invention and are equally protected by patent rights.

Claims

1. A method for preparing a hydrogen peroxide-modified bismuth-based composite photocatalytic material, characterized in that, Includes the following steps: Polyvinylpyrrolidone and citric acid were added to the alcohol solution and stirred. Then, silane coupling agent and thiourea were added, and stirring and heating were continued to obtain the reaction base solution. Bi2WO6 was added to the reaction substrate, sonicated, stirred, and heated to obtain modified Bi2WO6. Modified Bi2WO6 was added to water and stirred. Then H2O2-Bi2O2CO3 was added, and stirring and heating were continued to obtain hydrogen peroxide modified bismuth-based composite photocatalytic material. H2O2-Bi2O2CO3 is prepared through the following steps: Bismuth nitrate pentahydrate was added to the acid solution and stirred to obtain reaction solution A. Sodium carbonate and hexadecyltrimethylammonium bromide were added to water and stirred to obtain reaction solution B. Reaction solution B was added to reaction solution A, stirred, and heated to obtain Bi2O2CO3. Bi2O2CO3 was added to water, stirred, and then hydrogen peroxide was added. Stirring and heating were continued to obtain H2O2-Bi2O2CO3.

2. The preparation method of a hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 1, characterized in that, Bi2WO6 is prepared by the following steps: Sodium tungstate, ammonium fluoride and urea were added to the composite alcohol solution and stirred to obtain reaction solution I; Hexadecyltrimethylammonium bromide and ascorbic acid were added to the composite alcohol solution and stirred to obtain reaction solution II; Add reaction solution II to reaction solution I, stir, and heat to obtain Bi2WO6.

3. The preparation method of the hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 2, characterized in that, The composite alcohol solution is composed of ethylene glycol and water in a mass ratio of 7:3; the heating temperature for preparing Bi2WO6 is 150~190℃.

4. The preparation method of the hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 1, characterized in that, In the step of preparing H2O2-Bi2O2CO3, the acid solution is a nitric acid solution with a concentration of 1.5~2.5 mol / L; the heating temperature for preparing Bi2O2CO3 is 120-140℃.

5. The method for preparing the hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 1, characterized in that, In the step of preparing the reaction base liquid, the alcohol liquid is composed of anhydrous ethanol and water in a mass ratio of 8:2; in the step of preparing modified Bi2WO6, the heating temperature is 160~180℃.

6. A hydrogen peroxide-modified bismuth-based composite photocatalytic material, characterized in that, The hydrogen peroxide-modified bismuth-based composite photocatalyst was prepared using the preparation method described in any one of claims 1 to 5. The hydrogen peroxide-modified bismuth-based composite photocatalyst was prepared from Bi2WO6, H2O2-Bi2O2CO3, polyvinylpyrrolidone, citric acid, silane coupling agent and thiourea; the H2O2-Bi2O2CO3 was loaded on the surface of the modified Bi2WO6, and the two formed a closely contacted composite structure.

7. The hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 6, characterized in that, By weight, the hydrogen peroxide-modified bismuth-based composite photocatalyst material comprises the following components: 1.5-2.5 parts Bi2WO6, 0.22-0.42 parts H2O2-Bi2O2CO3, 0.6-0.9 parts polyvinylpyrrolidone, 0.05-0.15 parts citric acid, 0.1 parts silane coupling agent, and 0.3-0.6 parts thiourea.

8. The hydrogen peroxide-modified bismuth-based composite photocatalyst material according to claim 6, characterized in that, The H2O2-Bi2O2CO3 is prepared from sodium carbonate, bismuth nitrate pentahydrate, hexadecyltrimethylammonium bromide and hydrogen peroxide. The mass ratio of sodium carbonate: bismuth nitrate pentahydrate: hexadecyltrimethylammonium bromide: hydrogen peroxide is 3~4.5:6~9:0.5~0.9:1.

2.

9. The hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 6, characterized in that, The Bi2WO6 is prepared from sodium tungstate, bismuth nitrate pentahydrate, ammonium fluoride, urea, hexadecyltrimethylammonium bromide and ascorbic acid. By mass ratio, sodium tungstate: bismuth nitrate pentahydrate: ammonium fluoride: urea: hexadecyltrimethylammonium bromide: ascorbic acid is 1.5-2.5: 2-4: 0.6-0.9: 1-1.4: 0.4-0.8: 0.25-0.

5.

10. The application of the hydrogen peroxide-modified bismuth-based composite photocatalytic material according to claim 6 in the photocatalytic reduction of carbon dioxide and the photocatalytic reduction of nitrogen.

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