Preparation method and application of Ni-coated TpTD-COF photocatalytic material

Abstract

The invention relates to a preparation method and application of a Ni-coated TpTD-COF photocatalytic material. The invention provides a covalent organic framework material (Ni (at) TpTD-COF), and aims to solve the problem of low efficiency of photocatalytic synthesis of hydrogen peroxide by an existing covalent organic framework material. The first method comprises the preparation of TpTD-COF, and the second method comprises the preparation of Ni-coated TpTD-COF. The preparation process is simple and effective, the reagent consumption is low, and the yield is high; the photocatalyst provided by the invention can effectively improve the efficiency of photosynthesis of hydrogen peroxide. Experimental results show that the catalyst has good performance of photocatalytic synthesis of hydrogen peroxide, the hydrogen peroxide generation rate is 6000 [mu] mol.g <-1 >. H <-1 > under the condition that no metal Ni is added, and after the metal Ni is added, the performance is remarkably improved and is 9800 [mu] mol.g <-1 >. H <-1 >.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of a Ni@TpTD-COF photocatalytic material. Background Art

[0002] In recent years, energy crises and massive greenhouse gas emissions have become major global challenges. Developing green, renewable energy and achieving carbon recycling have emerged as promising solutions. As a green and environmentally friendly oxidant, hydrogen peroxide (H2O2) is in increasing demand, fueled by its importance in disinfection and epidemic prevention. In modern society, demand for hydrogen peroxide (H2O2) continues to grow. As a green oxidant, H2O2 has a wide range of applications in environmental remediation, wastewater treatment, and fine chemicals. Furthermore, H2O2 has recently been recognized as a promising clean fuel, with potential applications in new energy vehicles and aerospace. The products of hydrogen peroxide reactions are clean and pollution-free, making them suitable for the preparation of products such as bleaching agents, oxidants, and cross-linking agents. They are widely used in papermaking, textiles, and wastewater disinfection and decolorization. H2O2 is one of the world's 100 most important chemicals, with an annual production exceeding 4 million tons. Since its isolation in 1818, hydrogen peroxide (H2O2) has attracted widespread attention due to its various excellent properties. From the initial preparation of approximately 3wt% H2O2 using barium peroxide and sulfuric acid or phosphoric acid as raw materials, to the current development of anthraquinone oxidation method, electrolysis method, isopropyl alcohol method, direct hydrogen and oxygen synthesis method, electrocatalytic oxygen reduction method, photocatalytic synthesis method, etc., the current mainstream H2O2 production process in the world is based on anthraquinone oxidation method. This method has complex synthesis steps, high cost, dangerous production process, high energy consumption, and also causes certain environmental pollution. Therefore, the development of new green, environmentally friendly, low-cost and low-energy H2O2 preparation technology has important economic and social value. Photocatalytic synthesis of H2O2 has the advantages of safety, environmental protection and energy saving, meets the requirements of sustainable development, and has great development potential.

[0003] Covalent organic frameworks (COFs) are a new class of crystalline organic porous polymers composed of lightweight elements such as C, H, O, N, and S, connected by covalent bonds. They feature diverse building blocks, a rich variety of bonding types, highly controllable structural customization comparable to Lego building blocks, functionalizable molecular structures, and tunable optoelectronic properties. They have proven to be promising candidates for the photocatalytic production of H2O2. Covalent organic frameworks are porous crystalline materials formed from organic monomers through reversible covalent bonds. Due to their structural controllability, low density, high stability, porosity, and large specific surface area, they are currently being applied in gas storage, catalysis, optoelectronic devices, proton conduction, and energy storage. The synthesis of COFs is primarily achieved through thermodynamic manipulation, allowing small organic molecule building blocks to reversibly connect, ultimately forming 2D and 3D topological network structures with periodic backbones. COF itself is composed of lightweight organic units connected by covalent bonds, forming an ordered structure with high specific surface area and flexible pore size. Although pure COF is highly stable, it lacks metal active sites and has limited catalytic ability. Metal-organic frameworks contain metal sites, but the coordination bond stability is insufficient. The introduction of metallic nickel can combine the structural stability of COF with the catalytic activity of nickel to form a covalent metal-organic framework, which combines the advantages of both types of materials. Over the past 15 years, the tremendous progress made in the design, synthesis and functional exploration of COF has laid a solid foundation for its development in the field of covalent chemistry. The historical development of COF has provided comprehensive and clear guidance for molecular design, synthetic regulation and functional exploration, and has opened a new door for the application prospects of materials in the field of covalent chemistry. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of low efficiency of photosynthesis of hydrogen peroxide by existing covalent organic framework materials, and to provide a preparation method of TpTD-COF and photosynthesis of hydrogen peroxide.

[0005] The preparation method of a TpTD-COF material of the present invention is completed according to the following steps: First, TpTD-COF was prepared by sequentially charging a Schlonk glass tube with 1,3,5-triformylphloroglucinol (Tp) and 2,5-diamino-1,3,4-thiadiazole (TD), along with 1 mL of dimethyl sulfoxide (DMSO) and an ethanol solution. The mixture was sonicated for 10-15 minutes to obtain a uniform dispersion, followed by the addition of 0.2 mL of aqueous acetic acid. The Schlonk tube was rapidly frozen in a liquid nitrogen bath at 77K and degassed via three freeze-thaw cycles. Finally, the tube was heated at 120°C for 72 hours while sealed in a vacuum. The resulting precipitate was collected by centrifugation or filtration, washed five to six times with DMF and then acetone. The collected powder was solvent-exchanged with acetone three times and finally dried under vacuum at 60°C for 24 hours to yield TpTD-COF. The masses of 1,3,5-triformylphloroglucinol (Tp) and 2,5-diamino-1,3,4-thiadiazole (TD) described in the above steps are 10.5 mg and 8.711 mg respectively; The concentration of acetic acid added in the above steps is 6 mol·L -1 ; The above-mentioned TpTD-COF material is applied to the photocatalytic synthesis of hydrogen peroxide.

[0006] Beneficial effects of this article: In this paper, a solvothermal method was used to successfully synthesize TpTD-COF using 2,5-diamino-1,3,4-thiadiazole (TD) and 1,3,5-triformylphloroglucinol (Tp) as raw materials. The photosynthetic efficiency of hydrogen peroxide was 6000 μmol·g -1 ·h -1 In order to improve its efficiency, metal Ni was added, which significantly increased the efficiency to 9800 μmol·g -1 ·h -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is the X-ray powder diffraction pattern of TpTD-COF material; Figure 2 X-ray powder diffraction pattern of Ni@TpTD-COF material; Figure 3 The infrared spectra of TpTD-COF material and Ni@TpTD-COF material; Figure 4 Performance diagram of the photocatalytic synthesis of hydrogen peroxide by TpTD-COF and Ni@TpTD-COF materials. DETAILED DESCRIPTION The present invention is further described below with reference to the following examples. These examples are only used to illustrate the method of the present invention and do not limit the scope of application of the present invention.

[0008] Example 1: The preparation of a Ni@TpTD-COF material of this embodiment is completed according to the following steps: 1. Preparation of TpTD-COF: First, 1,3,5-triformylphloroglucinol (Tp) (10.5 mg) and 2,5-diamino-1,3,4-thiadiazole (TD) (8.711 mg) were placed in a Schronck glass tube, followed by 1 mL of dimethyl sulfoxide (DMSO) and ethanol solution. The mixture was sonicated for 10-15 minutes to obtain a uniform dispersion, and then 0.2 mL of 6.0 mol·L -1Aqueous acetic acid solution. The Schlonk tube was rapidly frozen at 77K (liquid nitrogen bath) and degassed through three freeze-thaw cycles. Finally, the tube was heated at 120°C for 72 hours while sealed in a vacuum state. The resulting precipitate was collected by centrifugation or filtration, washed 5-6 times with DMF and then acetone. The collected powder was solvent-exchanged with acetone three times and finally dried in vacuo at 60°C for 24 hours to obtain TpTD-COF. 2. Preparation of Ni@TpTD-COF: Weigh 30 mg of the prepared TpTD-COF and add appropriate amount of metal. Stir in methanol solution at room temperature for 8 h, then filter, wash and dry to obtain Ni@TpTD-COF. The following experiments were performed to verify the beneficial effects of the present invention: To investigate the photocatalytic performance of TpTD-COF and Ni@TpTD-COF materials in synthesizing hydrogen peroxide, their visible light photocatalytic performance was tested according to the following method. The test process is as follows: TpTD-COF and Ni@TpTD-COF were used as photocatalysts, deionized water was used as the reaction liquid, and ultrasonication was performed to form a suspension. The suspension was poured into a reactor and oxygen was introduced for 20 minutes to expel the air in the reactor. A xenon lamp was then used as the light source. After 30 minutes of illumination, the reaction suspension was taken out and filtered with a 1 mL needle with a filter to remove the catalyst and collect the liquid. The collected 1 mL of liquid was added to a 66.4 mg·mL -1 1 mL of potassium iodide solution with a solubility of 20.422 mg mL -1 0.5 mL of potassium hydrogen phthalate solution was added, mixed thoroughly and allowed to stand for 30 min, and analyzed using a UV-visible spectrophotometer. Figure 4 As shown in Figure 2, under visible light, the photocatalytic efficiency of TpTD-COF in synthesizing hydrogen peroxide was low, at 6000 μmol·g -1 ·h -1 ; Ni@TpTD-COF has a higher efficiency of 9800 μmol·g -1 ·h -1 .

Claims

1. A preparation method and application of Ni@TpTD-COF photocatalytic material. It is characterized in that The method proceeds as follows: I. Preparation of TpTD-COF: 1,3,5-Triformylphloroglucinol (Tp) and 2,5-diamino-1,3,4-thiadiazole (TD) were first charged into a Schlonk glass tube, followed by 1 mL of dimethyl sulfoxide (DMSO) and ethanol solutions. The mixture was sonicated for 10-15 minutes to obtain a uniform dispersion, followed by the addition of 0.2 mL of aqueous acetic acid. The Schlonk tube was rapidly frozen in a liquid nitrogen bath at 77K and degassed by three freeze-thaw cycles. Finally, the tube was heated at 120°C for 72 hours while sealed in a vacuum. The resulting precipitate was collected by centrifugation or filtration, washed five to six times with DMF and then acetone. The collected powder was solvent-exchanged with acetone three times and finally dried under vacuum at 60°C for 24 hours to yield TpTD-COF.

2. Preparation of Ni@TpTD-COF: Weigh 30 mg of the prepared TpTD-COF and add appropriate amount of metal. Stir in methanol solution at room temperature for 8 h, then filter, wash and dry to obtain Ni@TpTD-COF.

2. The preparation of a Ni@TpTD-COF material according to claim 1, characterized in that The masses of 1,3,5-triformylphloroglucinol (Tp) and 2,5-diamino-1,3,4-thiadiazole (TD) described in the above steps are 10.5 mg and 8.711 mg, respectively.

3. The preparation of a Ni@TpTD-COF material according to claim 1, characterized in that The concentration of acetic acid added in the above steps is 6 mol·L -1 .

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