Method for photocatalytic generation of hydrogen peroxide

Abstract

The application discloses a hydrogen peroxide photocatalytic generation method in the technical field of hydrogen peroxide processing, and a graphene-like preparation method. Urea and boric acid are used as reactants to prepare graphene-like BN by a calcination method; a Sv-MoS2 / BN composite material is synthesized by dissolving BN in deionized water, ultrasonic treatment for 30 min, then adding 1.4 g of thiourea and 0.6 g of (NH4)6Mo7O 24 4H2O into the solution, stirring for 30 min, hydrothermal reaction for 18 h, cooling to room temperature, then cleaning and drying for 8-12 h, obtaining defect-rich Sv-MoS2 / BN, and then obtaining samples with Sv-MoS2 / BN contents of 0.01, 0.03, 0.05 and 0.07 g, which are respectively marked as Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5 and Sv-MoS2 / BN-7; H2O2 generation: the obtained samples are respectively dissolved in 50 ml of deionized water, the reaction solution is stirred in the dark for 30 min before reaction, a 420 nm filter 300 w xenon lamp is used as a light source, the reaction is kept at 25 DEG C through a water circulation system, 3 ml of reaction suspension is taken out every certain time, solid substances are removed through a filter membrane, and then the generated H2O2 concentration is measured. The scheme aims to improve the efficiency of photocatalytic generation of H2O2.

Description

Technical Field

[0001] This invention relates to the field of hydrogen peroxide processing technology, specifically to a photocatalytic method for generating hydrogen peroxide. Background Technology

[0002] Hydrogen peroxide (H2O2) is a highly efficient oxidant and has even been used as a potential alternative energy carrier for H2, finding widespread application in environmental remediation, organic synthesis, sterilization, and bleaching. In recent years, driven by sustainable solar energy, photocatalytic O2 reduction reaction (ORR) to produce H2O2 has attracted considerable attention. Compared to traditional alcohol oxidation, anthraquinone oxidation, or electrocatalytic synthesis methods, photocatalysis offers advantages such as low cost, low energy consumption, non-toxic emissions, and operational feasibility, making it a promising method for synthesizing H2O2 on various scales.

[0003] However, materials such as TiO2, MoS2, Zn2In2S5, and BiVO4 are currently used for photocatalytic production of H2O2. Among them, MoS2, known as a multiphase material, has proven to be a promising catalyst due to its fascinating flexibility in controlling catalytic activity based on defect, phase, and geometry engineering. However, some inherent properties, such as rapid carrier recombination behavior, limited active sites, and poor selectivity for two-electron oxygen reduction, result in unsatisfactory photocatalytic activity in the MoS2 system. Therefore, overcoming the aforementioned shortcomings of pristine MoS2 is key to improving the efficiency of photocatalytic H2O2 production. Summary of the Invention

[0004] The present invention aims to provide a photocatalytic method for generating hydrogen peroxide, so as to improve the efficiency of photocatalytic generation of H2O2.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a photocatalytic generation method for hydrogen peroxide, comprising the following steps:

[0006] Step 1, Graphene-like preparation: Graphene-like BN is prepared by calcination using urea and boric acid as reactants.

[0007] Step 2, Synthesis of Sv-MoS2 / BN composite material: Graphene-like BN with concentrations of 0.01, 0.03, 0.05, and 0.07 g were dissolved in 60 mL of deionized water and sonicated for 30 min. Then, 1.4 g of thiourea and 0.6 g of (NH4)6Mo7O were added to the solution. 24·4H2O, continuously stirred for 30 min, then hydrothermally reacted at 210℃ for 18 h, then cooled to room temperature, washed, and dried at 60℃ for 8–12 h. After drying, defect-rich Sv-MoS2 / BN was obtained. The samples with Sv-MoS2 / BN contents of 0.01, 0.03, 0.05, and 0.07 g were designated as Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7, respectively.

[0008] Step 3, H2O2 generation: Dissolve the samples Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7 obtained in Step 2 in 50 mL of deionized water. Before the reaction, the reaction solution is stirred vigorously in the dark for 30 min to reach the adsorption-desorption equilibrium between the catalyst and oxygen. A 300 W xenon lamp with a 420 nm filter is used as the light source. The reaction is maintained at 25 °C through a water circulation system. During the photocatalytic reaction, 3 mL of the reaction suspension is extracted at regular intervals, and the solid substances are removed by filtration membrane. Then, the concentration of generated H2O2 is determined by standard iodometric titration.

[0009] The beneficial effects of this invention are as follows: This method, without adding a sacrificial agent, introduces sulfur vacancies through an O2 reduction reaction in pure water, forming Mo-N bonds. This enhances the separation of photogenerated carriers, increases the specific surface area of ​​Sv-MoS2 / BN, and provides more active sites for the photocatalytic reduction of O2 to H2O2. Therefore, the H2O2 generation activity of the Sv-MoS2 / BN composite material in this method is significantly improved.

[0010] Furthermore, in step one, when preparing graphene-like BN, 8g of urea and 2g of boric acid are co-dissolved in 60mL of deionized water to form a colorless and transparent solution. The solution is then heated at 80°C to evaporate the solvent until it recrystallizes into a white powder. The solution is then annealed at 900°C for 5 hours under a nitrogen flow at a heating rate of 5°C / min. Finally, the obtained product is ground into powder to obtain a white BN sample. Attached Figure Description

[0011] Figure 1 The image shows the XRD pattern of the synthesized material in an embodiment of the photocatalytic generation method for hydrogen peroxide according to the present invention.

[0012] Figure 2 SEM image of Sv-MoS2;

[0013] Figure 3 Here is a SEM image of Sv-MoS2 / BN in the example;

[0014] Figure 4The diagram shows the photocatalytic H2O2 generation activity of the synthesized materials in the examples;

[0015] Figure 5 This is a diagram of a cyclic experiment. Detailed Implementation

[0016] The following detailed description illustrates the specific implementation method:

[0017] Example

[0018] A photocatalytic method for generating hydrogen peroxide includes the following steps:

[0019] Step 1, Graphene-like preparation: Dissolve 8g of urea and 2g of boric acid in 60mL of deionized water to form a colorless and transparent solution. Heat at 80℃ to evaporate the solvent until it recrystallizes into a white powder. Then anneal at 900℃ for 5h under N2 flow at a heating rate of 5℃ / min. Finally, grind the obtained product into powder to obtain a white BN sample.

[0020] Step 2, Synthesis of Sv-MoS2 / BN composite material: Graphene-like BN with concentrations of 0.01 g, 0.03 g, 0.05 g, and 0.07 g were dissolved in 60 mL of deionized water and sonicated for 30 min. Then, 1.4 g of thiourea and 0.6 g of (NH4)6Mo7O were added to the solution. 24 ·4H2O, continuously stirred for 30 min, then hydrothermally reacted at 210℃ for 18 h, then cooled to room temperature, washed, and dried at 60℃ for 8–12 h. After drying, defect-rich Sv-MoS2 / BN was obtained. The samples with Sv-MoS2 / BN contents of 0.01, 0.03, 0.05, and 0.07 g were designated as Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7, respectively.

[0021] Step 3, H2O2 generation: Dissolve the samples Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7 obtained in Step 2 in 50 mL of deionized water. Before the reaction, the reaction solution is stirred vigorously in the dark for 30 min to reach the adsorption-desorption equilibrium between the catalyst and oxygen. A 300 W xenon lamp with a 420 nm filter is used as the light source. The reaction is maintained at 25 °C through a water circulation system. During the photocatalytic reaction, 3 mL of the reaction suspension is extracted at regular intervals, and the solid substances are removed by filtration membrane. Then, the concentration of generated H2O2 is determined by standard iodometric titration.

[0022] XRD was used to perform crystallographic and phase structure analysis on the prepared catalyst. (See attached image.) Figure 1 As shown, the signal peaks of the Sv-MoS2 sample perfectly match the hexagonal MoS2 (2H-MoS2, JCPDS No. 37-1492). For the XRD spectrum of Sv-MoS2 / BN-5, the additional peak points to the (002) plane of BN (JCPDS No. 34-0421). The XRD results indicate the successful synthesis of the Sv-MoS2 / BN composite material.

[0023] The morphology of the catalyst was characterized using SEM. (See attached image.) Figure 2 As shown, the pristine Sv-MoS2 exhibits a flower-like microsphere structure composed of numerous nanosheets. (See attached image.) Figure 3 The microstructure of the Sv-MoS2 / BN-5 composite material is shown, indicating that Sv-MoS2 nanosheets are uniformly grown on BN nanosheets.

[0024] The photocatalytic activity of the samples in generating H2O2 was evaluated by conducting an O2 reduction reaction in pure water without the addition of a sacrificial agent. (See attached image) Figure 4 As shown, Sv-MoS2 exhibits poor H2O2 production performance (171.18 μmol h⁻¹). -1 g -1 This may be because the rapid recombination of electron-hole pairs limits the photocatalytic activity. The H2O2 generation activity of the Sv-MoS2 / BN composite material is significantly improved, with Sv-MoS2 / BN-5 exhibiting the best H2O2 generation performance (428.17 μmol / h). -1 g -1 The H2O2 generation performance is 2.5 times that of Sv-MoS2. The improved H2O2 generation performance may be due to the introduction of sulfur vacancies, which form Mo-N bonds, enhance the separation of photogenerated carriers, increase the specific surface area of ​​Sv-MoS2 / BN, and provide more active sites for photocatalytic reduction of O2 to H2O2.

[0025] Multiple cyclic experiments were conducted under the same conditions to investigate the reusability of the photocatalyst. (See attached...) Figure 5 As shown, after four photocatalytic runs, the photocatalytic H2O2 production efficiency of Sv-MoS2 / BN-5 only decreased slightly (394.22 μmol / h). -1 g -1 This indicates that it has high reusability.

Claims

1. A photocatalytic method for generating hydrogen peroxide, characterized in that, Includes the following steps: Step 1, Graphene-like preparation: Graphene-like BN is prepared by calcination using urea and boric acid as reactants. Step 2, Synthesis of Sv-MoS2 / BN composite material: Graphene-like BN with concentrations of 0.01, 0.03, 0.05, and 0.07 g were dissolved in 60 mL of deionized water and sonicated for 30 min. Then, 1.4 g of thiourea and 0.6 g of (NH4)6Mo7O were added to the solution. 24 ·4H2O, continuously stirred for 30 min, then hydrothermally reacted at 210℃ for 18 h, then cooled to room temperature, washed, and dried at 60℃ for 8–12 h. After drying, defect-rich Sv-MoS2 / BN was obtained. The samples with Sv-MoS2 / BN contents of 0.01, 0.03, 0.05, and 0.07 g were designated as Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7, respectively. Step 3, H2O2 generation: Dissolve the samples Sv-MoS2 / BN-1, Sv-MoS2 / BN-3, Sv-MoS2 / BN-5, and Sv-MoS2 / BN-7 obtained in Step 2 in 50 mL of deionized water. Before the reaction, the reaction solution is stirred vigorously in the dark for 30 min to reach the adsorption-desorption equilibrium between the catalyst and oxygen. A 300 W xenon lamp with a 420 nm filter is used as the light source. The reaction is maintained at 25 °C through a water circulation system. During the photocatalytic reaction, 3 mL of the reaction suspension is extracted at regular intervals, and the solid substances are removed by filtration membrane. Then, the concentration of generated H2O2 is determined by standard iodometric titration.

2. The photocatalytic generation method for hydrogen peroxide according to claim 1, characterized in that: In step one, when preparing graphene-like BN, 8g of urea and 2g of boric acid are dissolved in 60mL of deionized water to form a colorless and transparent solution. The solution is heated at 80°C to evaporate the solvent until it recrystallizes into a white powder. Then, under N2 flow, it is annealed at 900°C for 5 hours at a heating rate of 5°C / min. Finally, the obtained product is ground into powder to obtain a white BN sample.

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