Photocatalytic material for hydrogen peroxide synthesis and preparation method and application thereof

Abstract

The invention relates to the field of photocatalytic materials, in particular to a photocatalytic material for hydrogen peroxide synthesis and a preparation method and application thereof. The preparation method of the photocatalytic material provided by the invention comprises the following steps: (1) grinding and mixing melamine, potassium chloride (KCl) and hexagonal phase boron nitride (h-BN) to obtain a uniform mixture; and (2) heating the uniform mixture to 500-650 DEG C, carrying out heat preservation treatment, cooling, grinding, washing, and drying to obtain the product. According to the preparation method, a molten salt effect of KCl and a dual-modification strategy of constructing a Type II heterojunction with h-BN are adopted, g-C3N4 is effectively modified, the potassium-doped g-C3N4 / h-BN composite photocatalytic material rich in nitrogen defects is prepared, the material has excellent activity of photocatalytic synthesis of H2O2 and good cycle stability, and the preparation method is suitable for industrial production. A new effective way can be provided for green and sustainable synthesis of hydrogen peroxide.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of materials science, energy science and environmental science, specifically to the field of photocatalytic materials, and more specifically to a photocatalytic material for hydrogen peroxide synthesis, its preparation method and application. Background Technology

[0002] Hydrogen peroxide (H2O2), as a green and efficient oxidant, has been widely used in organic synthesis, environmental remediation, medical disinfection, and energy storage. The decomposition products of H2O2 are only water and oxygen, which meets the development requirements of "atom economy" and "green chemistry" and is one of the key alternatives to traditional oxidants (such as potassium permanganate).

[0003] Currently, the mainstream method for preparing H2O2 in industry is the anthraquinone process. This method requires multiple steps such as anthraquinone hydrogenation, oxidation, extraction, and purification, and has the following significant drawbacks: (1) It relies on expensive and scarce precious metal (such as palladium) catalysts; (2) The reaction process requires the use of a large amount of organic reagents (such as heavy aromatics), which can easily cause environmental pollution and safety risks; (3) The production process is complex and energy consumption is high (it is necessary to maintain specific high temperature and high pressure conditions); (4) The product needs to be purified, making it difficult to meet the needs of "in-situ synthesis and immediate use" (such as on-site water treatment and emergency disinfection).

[0004] As an emerging technology, photocatalytic synthesis of H2O2 has attracted widespread attention from industry professionals in recent years. This technology uses solar energy as its driving force and water (H2O) and oxygen (O2) as its main raw materials. Through the photocatalytic action of suitable materials, it directly achieves the two-electron reduction reaction (2e⁻ ORR) of O2 or the oxidation reaction (WOR) of H2O. It boasts significant advantages such as operating at room temperature and pressure, zero pollution, and low cost, and is considered an ideal technological route for next-generation H2O2 synthesis.

[0005] The core of photocatalytic synthesis of H2O2 lies in the fact that the performance of the photocatalytic material must simultaneously meet requirements such as strong visible light response, high photogenerated carrier separation efficiency, good 2e⁻ ORR selectivity, and excellent chemical stability. Currently, mainstream H2O2 synthesis photocatalysts can be divided into metal-based materials (such as TiO2, BiVO4, etc.) and non-metal-based materials (such as graphitic carbon nitride, etc.). Among them, non-metal-based materials have become a recent research hotspot due to their low cost, absence of heavy metal pollution, and abundant element reserves.

[0006] Graphitic carbon nitride (g-C3N4) is a graphite-like layered non-metallic semiconductor photocatalytic material composed of C and N elements. Its band gap is approximately 2.7 eV, allowing it to effectively absorb visible light (wavelength ≤ 460 nm). It also possesses excellent chemical stability and a unique electronic structure (valence band position suitable for H2O oxidation, conduction band position suitable for O2 2e⁻ reduction), making it a promising candidate for photocatalytic water splitting, CO2 reduction, pollutant degradation, and H2O2 synthesis. However, bulk g-C3N4 exhibits drawbacks such as high photogenerated carrier recombination rate, small specific surface area, poor redox balance, and poor stability, limiting its industrial application and necessitating effective modification.

[0007] Based on the current state of research, how to effectively modify g-C3N4 to prepare catalytic materials with excellent photocatalytic activity for H2O2 synthesis and good cycle stability is of great practical significance and urgent need for breaking through the technical bottleneck of photocatalytic H2O2 synthesis. Summary of the Invention

[0008] To address the shortcomings of the existing technology, the primary objective of this invention is to provide a method for preparing a photocatalytic material for hydrogen peroxide synthesis. This method employs a dual modification strategy, utilizing the molten salt effect of potassium chloride (KCl) and constructing a Type II heterojunction with hexagonal boron nitride (h-BN), to effectively modify g-C3N4. This results in the preparation of a potassium-doped g-C3N4 / h-BN composite catalytic material rich in nitrogen defects. This material exhibits both excellent photocatalytic activity for H2O2 synthesis and good cycling stability, making it suitable for the technical application of photocatalytic H2O2 synthesis.

[0009] The second objective of this invention is to provide a photocatalytic material for hydrogen peroxide synthesis prepared by the above-described method, which exhibits excellent photocatalytic activity for H2O2 synthesis and good cycle stability.

[0010] A third objective of this invention is to provide the application of photocatalytic materials for the synthesis of hydrogen peroxide, specifically in the photocatalytic preparation of hydrogen peroxide.

[0011] To achieve the above objectives, the first aspect of the present invention adopts the following technical solution: A method for preparing a photocatalytic material for hydrogen peroxide synthesis includes the following steps: (1) Melamine, potassium chloride and hexagonal boron nitride are ground and mixed to obtain a uniform mixture; wherein the mass ratio of melamine, potassium chloride and hexagonal boron nitride is (3.5~4.5)∶(1.8~2.2)∶(0.2~0.8); (2) The uniform mixture is heated to 500~650℃ for heat preservation treatment, and then cooled, ground, washed and dried to obtain the photocatalytic material for hydrogen peroxide synthesis.

[0012] As a further option, in step (1), the grinding and mixing time is 10~60 min.

[0013] As a further option, in step (1), anhydrous ethanol is added as a grinding aid during the grinding and mixing process.

[0014] As a further option, in step (1), the particle size of the hexagonal boron nitride is less than 150 nm.

[0015] To improve the photocatalytic activity and cycle stability of H2O2 synthesis, as a further step, in step (1), the mass ratio of melamine, potassium chloride, and hexagonal boron nitride is (3.5~4.5):(1.8~2.2):(0.4~0.8). More preferably, the mass ratio of melamine, potassium chloride, and hexagonal boron nitride is 4:2:(0.4~0.8). More preferably, the mass ratio of melamine, potassium chloride, and hexagonal boron nitride is 4:2:0.4.

[0016] As a further option, in step (2), the heating rate is 1~5℃ / min; the heat preservation time is 2~4h.

[0017] As a further embodiment, in step (2), the cooling is natural cooling; the grinding time is 5-30 minutes; the washing is performed by vacuum filtration washing using hot water and anhydrous ethanol respectively; and the drying temperature is 60-100°C. More preferably, the temperature of the hot water is 60-100°C.

[0018] The second aspect of this invention is the following technical solution: A photocatalytic material for hydrogen peroxide synthesis prepared by the method described above.

[0019] The third aspect of this invention is the following technical solution: An application of a photocatalytic material for hydrogen peroxide synthesis as described above, wherein the application is the use of the photocatalytic material in the photocatalytic preparation of hydrogen peroxide.

[0020] As a further embodiment, the photocatalytic preparation of hydrogen peroxide specifically involves a hydrogen peroxide synthesis reaction carried out under light conditions using water and oxygen as the main raw materials; the light conditions are full-spectrum light or visible light.

[0021] Compared with the prior art, the outstanding advantages of the present invention are: The photocatalytic material preparation method provided by this invention includes grinding, calcining, and subsequent purification steps of a graphitic carbon nitride precursor, molten salt, and hexagonal boron nitride. This method offers advantages such as simple process, ease of operation, and low cost. In this invention, the molten salt effect of KCl and a dual modification strategy involving the construction of a Type II heterojunction with h-BN are used to composite modify g-C3N4, thereby preparing a molten salt-modified graphitic carbon nitride-hexagonal boron nitride composite photocatalytic material. The modified graphitic carbon nitride retains its crystal structure and possesses potassium ion doping and nitrogen defects, endowing the photocatalytic material with excellent photocatalytic activity for H2O2 synthesis and good cycling stability.

[0022] The photocatalytic material provided by this invention combines modified graphitic carbon nitride with hexagonal boron nitride. The synergistic effect of these two materials broadens the light absorption range and improves the separation efficiency and migration rate of photogenerated carriers, thereby significantly enhancing photocatalytic performance. Experiments have confirmed that the photocatalytic material prepared by this invention can be effectively applied to the photocatalytic synthesis of hydrogen peroxide. Under conditions using water and oxygen as the main raw materials and simulating visible light or sunlight irradiation, it exhibits excellent hydrogen peroxide catalytic synthesis effects, with a yield significantly higher than traditional photocatalysts. Furthermore, it demonstrates good stability, can be recycled multiple times, and is suitable for full-spectrum photocatalytic synthesis applications. In addition, the process of this invention utilizes abundant raw materials, has low preparation costs, is simple, and is easy to scale up. The photocatalytic synthesis of H2O2 is also easy to operate and highly efficient, overcoming the shortcomings of existing photocatalytic composite materials such as complex preparation processes, limited modification methods, weak interfacial bonding, and insufficient stability.

[0023] Therefore, this invention can provide a new and effective way for the green and sustainable synthesis of hydrogen peroxide. It is also conducive to the transformation of H2O2 from high-pollution synthesis and high-risk application to zero-pollution synthesis and wide-scenario empowerment. It is also conducive to promoting pollution reduction and collaborative governance, and has broad application prospects in environmental protection, chemical synthesis, energy and other fields. Attached Figure Description

[0024] Figure 1 X-ray diffraction patterns of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) of the present invention; Figure 2 X-ray photoelectron fine spectra of C 1s and K 2p of the photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4) of the present invention; Figure 3The electron paramagnetic resonance spectra of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) of the present invention are shown. Figure 4 The steady-state fluorescence spectra of the photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4) of this invention; Figure 5 The transient photocurrent curves of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) of the present invention are shown. Figure 6 Electrochemical impedance spectroscopy of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) of the present invention. Detailed Implementation

[0025] The technical solution and technical effects of the present invention will be further described below with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only used to explain the present invention and should not be construed as limiting the scope of protection of the present invention.

[0026] Unless otherwise specified, all reagents and materials used in the following examples are conventional reagents and materials in the art and can be obtained commercially. Specifically, the hexagonal boron nitride (h-BN) used in the following embodiments is commercial nano-boron nitride, CAS: 10043-11-5, purity: metal standard greater than 99.8%, particle size: less than 150 nm. In the following examples, room temperature has a conventional understanding in the art, typically referring to 25±5℃.

[0027] Example 1

[0028] This embodiment provides a photocatalytic material for hydrogen peroxide synthesis, the preparation method of which includes the following steps: (1) Weigh 4g of melamine, 2g of potassium chloride and 0.8g of h-BN into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a uniform mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) The solid obtained after cooling in step (2) is ground in an agate mortar for 10 minutes, and then washed by vacuum filtration with hot deionized water at 90°C and anhydrous ethanol respectively. The resulting filter cake is then dried in an oven at 80°C to obtain the photocatalytic material for hydrogen peroxide synthesis in this embodiment (denoted as MCN / BN-1).

[0029] Example 2

[0030] This embodiment provides a photocatalytic material for hydrogen peroxide synthesis, the preparation method of which includes the following steps: (1) Weigh 4g of melamine, 2g of potassium chloride and 0.4g of h-BN into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a uniform mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) The solid obtained after cooling in step (2) is ground in an agate mortar for 10 minutes, and then washed by vacuum filtration with hot deionized water at 90°C and anhydrous ethanol respectively. The resulting filter cake is then dried in an oven at 80°C to obtain the photocatalytic material for hydrogen peroxide synthesis in this embodiment (denoted as MCN / BN-2).

[0031] Example 3

[0032] This embodiment provides a photocatalytic material for hydrogen peroxide synthesis, the preparation method of which includes the following steps: (1) Weigh 4g of melamine, 2g of potassium chloride and 0.2g of h-BN into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a uniform mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) The solid obtained after cooling in step (2) is ground in an agate mortar for 10 minutes, and then washed by vacuum filtration with hot deionized water at 90°C and anhydrous ethanol respectively. The resulting filter cake is then dried in an oven at 80°C to obtain the photocatalytic material for hydrogen peroxide synthesis in this embodiment (denoted as MCN / BN-4).

[0033] Comparative Example 1 This comparative example provides a photocatalytic material, specifically a KCl molten salt effect modified graphitic carbon nitride material (Modified g-C3N4), the preparation method of which includes the following steps: (1) Weigh 4g of melamine and 2g of potassium chloride into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a uniform mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) The solid obtained after cooling in step (2) is ground in an agate mortar for 10 minutes, and then washed by vacuum filtration with hot deionized water at 90℃ and anhydrous ethanol respectively. The resulting filter cake is then dried in an oven at 80℃ to obtain the photocatalytic material of the comparative example (denoted as Modified g-C3N4).

[0034] Comparative Example 2 This comparative example provides a photocatalytic material, specifically an untreated hexagonal boron nitride raw material (denoted as h-BN).

[0035] Comparative Example 3 This comparative example provides a photocatalytic material, specifically a graphitic carbon nitride (g-C3N4) material that has not been modified by the KCl molten salt effect, and its preparation method includes the following steps: (1) Weigh 4g of melamine, place it in a 100mL corundum crucible, raise the temperature to 600℃ at a rate of 3℃ / min and hold for 3h, then let it cool naturally to room temperature; (2) Grind the solid obtained after cooling in step (1) in an agate mortar for 10 minutes to obtain the photocatalytic material of the comparative example (denoted as g-C3N4).

[0036] Comparative Example 4 This comparative example provides a photocatalytic material, specifically a composite material of graphitic carbon nitride (g-C3N4) and h-BN without KCl molten salt effect modification, and its preparation method includes the following steps: (1) Weigh 4g of melamine and 0.4g of h-BN into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a homogeneous mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) Grind the solid obtained after cooling in step (2) in an agate mortar for 10 minutes to obtain the photocatalytic material of the comparative example (denoted as CN / BN).

[0037] Comparative Example 5 This comparative example provides a photocatalytic material, the preparation method of which includes the following steps: (1) Weigh 4g of melamine, 2g of potassium chloride and 1.6g of h-BN into an agate mortar, add 5 drops of anhydrous ethanol, grind for 30 minutes to obtain a uniform mixture; (2) Place the homogeneous mixture in a 100 mL corundum crucible, raise the temperature to 600 °C at a rate of 3 °C / min and hold for 3 h, then allow it to cool naturally to room temperature; (3) The solid obtained after cooling in step (2) is ground in an agate mortar for 10 minutes, and then washed by vacuum filtration with hot deionized water at 90℃ and anhydrous ethanol respectively. The resulting filter cake is then dried in an oven at 80℃ to obtain the photocatalytic material of the comparative proportion (denoted as MCN / BN-0.5).

[0038] Experimental Example 1: Structural Characterization (1) X-ray diffraction analysis The photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) were characterized using an X'Pert Pro X-ray diffractometer (Cu Kα-ray source, tube voltage 40 kV, tube current 40 mA). The obtained X-ray diffraction patterns are shown below. Figure 1 As shown.

[0039] Depend on Figure 1 It can be seen that Modified g-C3N4 exhibits the characteristic diffraction peaks of the (002) crystal plane of graphitic carbon nitride. Meanwhile, due to the condensation of the conjugated framework caused by the molten salt effect of KCl, the (100) crystal phase diffraction peak of Modified g-C3N4 shifts to a lower angle compared to conventional graphitic carbon nitride. MCN / BN-2 simultaneously exhibits characteristic diffraction peaks of both Modified g-C3N4 and h-BN, confirming their successful recombination.

[0040] (2) X-ray photoelectron spectroscopy analysis The photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4) were structurally characterized using an AXIS Supra X-ray photoelectron spectrometer (with charge correction based on C 1s = 248.6 eV). The fine C 1s and K 2p X-ray photoelectron spectra of the photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4) are shown below. Figure 2 As shown.

[0041] Depend on Figure 2 It can be seen that K 2p 1 / 2 and K 2p 3 / 2 The appearance of characteristic peaks confirms that the molten salt effect of KCl introduces potassium ion doping into the modified g-C3N4 and MCN / BN-2 g-C3N4 frameworks. Simultaneously, in addition to C–C, the figure also shows peaks corresponding to nitrogen-containing aromatic framework rings (N–C=N) and cyano groups (–C≡N), indicating that the molten salt effect of KCl also introduces nitrogen defects into g-C3N4.

[0042] (3) Electron paramagnetic resonance spectroscopy analysis The photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) were structurally characterized using a Bruker EMX-9.5 / 12 electron paramagnetic resonance spectrometer at room temperature. The obtained electron paramagnetic resonance spectra are shown below. Figure 3 As shown.

[0043] Depend on Figure 3 It can be seen that, unlike the h-BN phase which has no obvious signal, both Modified g-C3N4 and MCN / BN-2 show symmetrical peaks at a g-factor of approximately 2.003, indicating that the composite material effectively retains the sp2 of pure Modified g-C3N4. 2 The unpaired electrons on carbon atoms (i.e. nitrogen defects) are beneficial for surface catalytic reactions.

[0044] Experimental Example 2: Photoelectric Performance Testing Steady-state fluorescence spectroscopy was performed on the photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4). Transient photocurrent and electrochemical impedance spectroscopy were further performed on the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN).

[0045] The steady-state fluorescence spectroscopy was tested using a HITACHI F-4600 photoluminescence spectrophotometer with an excitation wavelength of 365 nm. The transient photocurrent and electrochemical impedance spectroscopy were tested using a CHI 760E electrochemical workstation with 0.5 M sodium sulfate solution as the electrolyte. An Ag / AgCl electrode served as the reference electrode, and a Pt wire electrode served as the counter electrode. The working electrode was prepared as follows: 10 mg of photocatalytic material was weighed and ultrasonically dispersed in a mixture of 50 μL Nafion solution, 125 μL anhydrous ethanol, and 375 μL high-purity water. The resulting suspension was dropped onto the conductive surface of a fluorine-doped tin oxide (FTO) glass (1 cm × 1 cm) and dried under an infrared lamp. The visible light source used for the transient photocurrent test was a 300 W xenon lamp equipped with a filter.

[0046] The steady-state fluorescence spectra of the photocatalytic materials provided in Example 2 (MCN / BN-2) and Comparative Example 1 (Modified g-C3N4) are as follows: Figure 4 As shown. The transient photocurrent curves of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) are as follows. Figure 5As shown. The electrochemical impedance spectra of the photocatalytic materials provided in Example 2 (MCN / BN-2), Comparative Example 1 (Modified g-C3N4), and Comparative Example 2 (h-BN) are as follows. Figure 6 As shown.

[0047] Depend on Figure 4-6 It is evident that the steady-state fluorescence intensity of MCN / BN-2 is significantly lower than that of pure Modified g-C3N4. Furthermore, compared to pure Modified g-C3N4 and h-BN, under the same illumination conditions, this composite material exhibits a higher photocurrent density and a smaller impedance spectrum radius. These results indicate that the dual modification strategy of KCl molten salt effect and Type II heterojunction effectively suppresses the recombination of photogenerated electron-hole pairs and greatly promotes the separation and migration of photogenerated carriers, thereby enhancing the photocatalytic performance of this composite material.

[0048] Experimental Example 3: Application Effects of Photocatalytic Synthesis of H2O2 This experiment investigated the application effect of the photocatalytic materials provided in Examples 1-3 and Comparative Examples 1-5 on the photocatalytic synthesis of H2O2 under simulated visible light. The test method was as follows: Measure 150 mL of ethanol-water solution (10%, v / v) and pour it into a double-jacketed quartz reactor with top illumination. Add 75 mg of photocatalyst material to the reactor, turn on the magnetic stirrer (580 r / min), start the DL-2005 low-temperature circulation device, set the temperature to 15℃, and continuously introduce high-purity oxygen (40 mL / min). Stir for 1 h under no-light conditions to reach adsorption-desorption equilibrium. Then turn on the xenon lamp source (with a 420 nm cutoff filter) and conduct the hydrogen peroxide synthesis reaction under simulated visible light and room temperature (25℃) conditions for 4 h. During this period, every 30 seconds... Min used a syringe to take 5 mL of the suspension, centrifuged it, and then measured 1.0 mL of the supernatant into a 5 mL volumetric flask. Diluted it to 5 mL with high-purity water. Next, measured 2.0 mL of the diluted solution and mixed it with 2.0 mL of potassium iodide solution (0.4 mol / L) and 2.0 mL of dipotassium hydrogen phosphate solution (0.1 mol / L). After standing in the dark for 1 hour, the absorbance of the resulting solution was quantitatively measured (λ=350 nm) using a TU-1901 UV-Vis spectrophotometer. Then, the synthesis rate of H2O2 (the number of moles of H2O2 produced per gram of catalyst per hour) was calculated by combining it with the standard working curve.

[0049] The results of the photocatalytic synthesis rate determination of H2O2 using the photocatalytic materials of Examples 1-3 and Comparative Examples 1-5 are shown in Table 1.

[0050] Table 1. Results of the photocatalytic synthesis rate of H2O2

[0051] As shown in Table 1, the photocatalytic materials prepared in Examples 1-3 of this invention have a photocatalytic synthesis rate of H2O2 as high as 763.42-1532.80 μmol / (g·h), which is significantly better than the photocatalytic materials in Comparative Examples 1-5. This indicates that the photocatalytic materials prepared in this invention have excellent photocatalytic synthesis activity for H2O2.

[0052] Furthermore, the xenon lamp source was replaced with a xenon lamp source without a 420nm cutoff filter (i.e., simulated full-spectrum light), and all other test conditions remained the same. The synthesis rate of H2O2 by photocatalytic synthesis using the photocatalytic material MCN / BN-2 provided in Example 2 was measured. The test results showed that the photocatalytic synthesis rate of H2O2 by MCN / BN-2 was as high as 3406.23 μmol / (g·h), indicating that it has good photocatalytic activity under full-spectrum light conditions and is suitable for photocatalytic applications under multispectral conditions.

[0053] Experimental Example 4: Cyclic Performance Test of Photocatalytic Synthesis of H2O2 After the photocatalytic experiment of the MCN / BN-2 photocatalytic material in Example 2 of Experiment 3 was completed, the suspension in the photocatalytic reaction bottle was transferred to an oven at 120°C to evaporate the solvent and dry it, and then directly applied to the next photocatalytic synthesis of H2O2 experiment (the part less than 75mg was supplemented by fresh MCN / BN-2), and the other test conditions were the same as in Experiment 3.

[0054] The cycling performance test results showed that the H2O2 synthesis rates in four consecutive cycles were 1532.80 μmol / (g·h), 1511.46 μmol / (g·h), 1501.15 μmol / (g·h), and 1485.21 μmol / (g·h), respectively. The rate retention of H2O2 synthesis after four cycles was as high as 96.9%, indicating that the photocatalytic material prepared in this invention has excellent cycling stability and a long service life.

[0055] In summary, the photocatalytic material provided by this invention exhibits excellent hydrogen peroxide synthesis performance under both simulated visible light and full-spectrum light irradiation, with hydrogen peroxide synthesis rates reaching 1532.80 μmol / (g·h) and 3406.23 μmol / (g·h), respectively. Furthermore, the H2O2 synthesis rate retention rate is as high as 96.9% after four cycles. Therefore, compared to traditional photocatalysts, the photocatalytic material provided by this invention possesses superior photocatalytic activity for hydrogen peroxide synthesis and good cycling stability, showing broad application prospects in the photocatalytic synthesis of hydrogen peroxide.

Claims

1. A method for preparing a photocatalytic material for hydrogen peroxide synthesis, characterized in that, Includes the following steps: (1) Melamine, potassium chloride and hexagonal boron nitride are ground and mixed to obtain a uniform mixture; wherein the mass ratio of melamine, potassium chloride and hexagonal boron nitride is (3.5~4.5)∶(1.8~2.2)∶(0.2~0.8); (2) The uniform mixture is heated to 500~650℃ for heat preservation treatment, and then cooled, ground, washed and dried to obtain the photocatalytic material for hydrogen peroxide synthesis.

2. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to claim 1, characterized in that, In step (1), the grinding and mixing time is 10~60 min.

3. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to claim 1, characterized in that, In step (1), anhydrous ethanol is added as a grinding aid during the grinding and mixing process.

4. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to claim 1, characterized in that, In step (1), the particle size of the hexagonal boron nitride is less than 150 nm.

5. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to claim 1, characterized in that, In step (1), the mass ratio of melamine, potassium chloride, and hexagonal boron nitride is 4:2:0.

4.

6. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to any one of claims 1 to 5, characterized in that, In step (2), the heating rate is 1~5℃ / min; the heat preservation time is 2~4h.

7. The method for preparing the photocatalytic material for hydrogen peroxide synthesis according to any one of claims 1 to 5, characterized in that, In step (2), the cooling is natural cooling; the grinding time is 5~30 min; the washing is carried out by vacuum filtration washing with hot water and anhydrous ethanol respectively; and the drying temperature is 60~100℃.

8. A photocatalytic material for hydrogen peroxide synthesis prepared by the preparation method according to any one of claims 1 to 7.

9. The application of a photocatalytic material for hydrogen peroxide synthesis as described in claim 8, characterized in that, The application is the use of photocatalytic materials in the photocatalytic preparation of hydrogen peroxide.

10. The application of the photocatalytic material for hydrogen peroxide synthesis according to claim 9, characterized in that, The photocatalytic preparation of hydrogen peroxide specifically involves a hydrogen peroxide synthesis reaction carried out under light conditions using water and oxygen as the main raw materials; the light conditions are full-spectrum light or visible light.

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