Preparation of COF-316 / Pt@TpBpy-COF composite material and photocatalytic decomposition of water

Abstract

The present application relates to a kind of COF-316 / Pt@TpBpy-COF composite material preparation and photocatalytic decomposition of water.The present application provides a new COF-316 / Pt@TpBpy-COF composite material, to solve the problem of low light utilization and electron hole easy recombination when existing TpBpy-COF photocatalytic decomposition of water.Method: one, the preparation of Pt NPS;Two, the preparation of COF-316;Three, the preparation of COF-316 / Pt@TpBpy-COF composite material.The preparation process of the present application is simple and effective, reagent consumption is less and performance is high;And the photocatalyst provided by the present application can effectively improve the problem of low photocatalytic decomposition of water efficiency.The present application is applied to the field of photocatalytic decomposition of water, and experiment shows that the composite material has excellent photocatalytic decomposition of water performance, and the decomposition water hydrogen production rate can reach 220.4 μmol·h ‑1 ·g ‑1 Under visible light irradiation, and the oxygen production efficiency is 101.5 μmol·h ‑1 ·g ‑1 .

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a COF-316 / Pt@TpBpy-COF composite material and application of the composite material in photocatalytic decomposition of water. BACKGROUND

[0002] With the rapid development of society and the continuous increase of population, the demand for energy by human beings is increasing day by day, and the burning of fossil fuels inevitably leads to two problems of fossil energy shortage and ecological environment pollution. Therefore, it is particularly important to develop and utilize clean and renewable green energy to replace fossil energy and change the environmental pollution problem. Among many energies, hydrogen energy has the advantages of being renewable, high energy density and zero pollution, and is considered to be one of the most promising energies to solve the energy crisis. Producing hydrogen and oxygen by photocatalytic decomposition of water driven by inexhaustible solar energy is a most clean and effective way. However, due to the problem of easy recombination of electrons and holes in single-component photocatalysts, the efficiency of water splitting is extremely low. Therefore, building a heterojunction, making the most of visible light and improving the efficiency of electron-hole separation is a relatively effective way.

[0003] Covalent organic frameworks (COFs) are a new type of crystalline porous material connected by covalent bonds, mainly composed of light elements such as H, C, O and N, and have the advantages of adjustable nanopore size, high specific surface area, pre-designed building units, rich active sites, programmable chain structure and topological structure, which makes COFs have a potential application prospect in many fields such as gas adsorption and separation, catalysis, sensing, energy storage and photoelectric conversion and is widely developed. However, single-component COF photocatalysts have the problem of easy recombination of electrons and holes, which limits the hydrogen and oxygen production activity of the COF photocatalyst. Therefore, building a heterojunction to improve the efficiency of water splitting of a double-component photocatalyst has become a research hotspot. SUMMARY

[0004] The purpose of the application is to solve the problems of easy recombination of electrons and holes in single-component photocatalysts and low efficiency of water splitting, and provide a preparation method of a COF-316 / Pt@TpBpy-COF composite material and application of the composite material in photocatalytic decomposition of water.

[0005] The preparation method of the COF-316 / Pt@TpBpy-COF composite material according to the application is completed by the following steps:

[0006] I. Preparation of COF-316 / Pt@TpBpy-COF composite material: N,N-dimethylacetamide (DMA) solution containing PtNPS, 5,5-diamino-2,2-bipyridine, 1,3,5-triformylphloroglucinol, COF-316 are added into a heat-resistant glass tube, and o-dichlorobenzene and DMA are sequentially added, and ultrasonic treatment is carried out under the condition that the ultrasonic frequency is 35-45 KHz for 30-35 min, then 6 mol·L -1 -1 of acetic acid solution is added, and the mixture is cyclically frozen and degassed in liquid nitrogen for three times, and then the mixture is sealed and heated at 120 DEG C for 72 h, and then the mixture is filtered and sequentially washed with DMA and ethanol for several times, and then the mixture is vacuum dried at 60 DEG C to obtain a red-brown powder, which is the COF-316 / Pt@TpBpy-COF composite material.

[0007] The concentration of the DMA solution containing PtNPS used in step one is 2.96 mg / ml;

[0008] The mass ratio of PtNPS to TpBpy-COF in step one is 0.05:1;

[0009] The mass ratio of COF-316 to TpBpy-COF in step one is 0.8:9.2-4:6;

[0010] The molar ratio of 5,5-diamino-2,2-bipyridine to 1,3,5-triformylphloroglucinol in step one is 3:2;

[0011] The volume ratio of o-dichlorobenzene, DMA and acetic acid in step one is 0.5:1.5:0.2;

[0012] The mixture is sealed and heated at 120 DEG C for 72 h in step one.

[0013] The COF-316 / Pt@TpBpy-COF composite material is used in photocatalytic decomposition of water.

[0014] The beneficial effects of the present application are:

[0015] The present application adopts a solvothermal method, and successfully synthesizes Pt@TpBpy-COF by in-situ adding PtNPS with 5,5-diamino-2,2-bipyridine and 1,3,5-triformylphloroglucinol as raw materials, but the efficiency of the material in decomposing water under visible light is relatively low, which is 96.0 μmol·h -1 ·g -1 Therefore, the present application composites Pt@TpBpy-COF with another crystalline porous material COF-316 to synthesize a COF-316 / Pt@TpBpy-COF composite material, and the material effectively improves the photocatalytic decomposition of water performance, and the hydrogen production efficiency is 140.4-220.4 μmol·h -1·g -1 The oxygen production efficiency is 66.0-105.2 μmol·h -1 ·g -1 . BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 X-ray powder diffraction pattern of the COF-316 / Pt@TpBpy-COF material;

[0017] Figure 2 Infrared spectrum of the COF-316 / Pt@TpBpy-COF material;

[0018] Figure 3 Photocatalytic water decomposition performance of the COF-316 / Pt@TpBpy-COF material. DETAILED DESCRIPTION

[0019] The application will be further described in the following examples, which only illustrate the method of the application and do not limit the scope of application of the application.

[0020] Example 1: The preparation of a COF-316 / Pt@TpBpy-COF material of the present embodiment is completed according to the following steps:

[0021] I. Preparation of Pt nanoparticles: A chloroplatinic acid solution, polyvinylpyrrolidone (PVP), an ethylene glycol solution containing sodium hydroxide, and ethylene glycol were added to a three-necked flask, and heated under stirring in a vacuum state at 180℃ for 3 min. After cooling to room temperature, the obtained solution was centrifuged with acetone and washed with n-hexane for several times. The final nanoparticles were dispersed in 2 ml of DMA.

[0022] The concentration of the chloroplatinic acid solution in step one is 7.4 mg / ml;

[0023] The concentration of the ethylene glycol solution containing sodium hydroxide in step one is 0.2 mol·L -1 ;

[0024] The volume ratio of the chloroplatinic acid solution, the ethylene glycol solution containing sodium hydroxide, and ethylene glycol in step one is 0.5:1:5;

[0025] The concentration of the DMA solution containing PtNPS in step one is 2.96 mg / ml.

[0026] II. Preparation of COF-316: 2,3,6,7,10,11-hexahydroxytriphenylbenzene (HHTP), tetrafluoro-p-phenylenedinitrile (TFPN) were added into a heat-resistant glass tube, and 1,4-dioxane and triethylamine were added in turn, and ultrasonic treatment was carried out at an ultrasonic frequency of 35-45 KHz for 30-35 min, and the liquid was degassed in liquid nitrogen for 3 times, and after sealing, heating was carried out at 120°C for 72 h, and filtration was carried out and washed with N,N-dimethylformamide (DMF), ethanol several times, and yellow powder was obtained after vacuum drying at 60°C, which was COF-316.

[0027] The mass ratio of HHTP and TFPN in step two is 10:9.2;

[0028] The volume ratio of 1.4-dioxane and triethylamine in step two is 2:0.078;

[0029] After sealing in step three, heating is carried out at 120°C for 72 h.

[0030] III. Preparation of COF-316 / Pt@TpBpy-COF composite material: N,N-dimethylacetamide (DMA) solution containing PtNPS, 5,5-diamino-2,2-bipyridine, 1,3,5-triformylphloroglucinol, COF-316 were added into a heat-resistant glass tube, and o-dichlorobenzene and DMA were added in turn, and ultrasonic treatment was carried out at an ultrasonic frequency of 35-45 KHz for 30-35 min, and then 6 mol·L -1 -1 acetic acid solution was added, and the liquid was degassed in liquid nitrogen for 3 times, and after sealing, heating was carried out at 120°C for 72 h, and filtration was carried out and washed with DMA, ethanol several times, and red-brown powder was obtained after vacuum drying at 60°C, which was COF-316 / Pt@TpBpy-COF composite material;

[0031] The concentration of the DMA solution containing PtNPS used in step three is 2.96 mg / ml;

[0032] The mass ratio of PtNPS and TpBpy-COF in step three is 0.05:1;

[0033] The mass ratio of COF-316 and TpBpy-COF in step three is 0.8:9.2-4:6;

[0034] The molar ratio of 5,5-diamino-2,2-bipyridine and 1,3,5-triformylphloroglucinol in step three is 3:2;

[0035] The volume ratio of o-dichlorobenzene, DMA and acetic acid in step three is 0.5:1.5:0.2;

[0036] After sealing as described in step three, heat at 120°C for 72 hours.

[0037] Example 2: This embodiment differs from Example 1 in that the mass of COF-316 in step two is 2.15 mg, and the other steps and parameters are the same as in Example 1; a COF-316 / Pt@TpBpy-COF composite material (mass ratio of 1:9) is obtained.

[0038] Example 3: This embodiment differs from Example 1 or 2 in that the mass of COF-316 in step three is 4.83 mg, and the other steps and parameters are the same as in Example 1 or 2; a COF-316 / Pt@TpBpy-COF composite material (mass ratio of 2:8) is obtained.

[0039] Example 4: This embodiment differs from Examples 1 to 3 in that the mass of COF-316 in step 3 is 8.28 mg, and the other steps and parameters are the same as in Examples 1 to 3; a COF-316 / Pt@TpBpy-COF composite material (mass ratio of 3:7) is obtained.

[0040] Example 5: This embodiment differs from Examples 1 to 4 in that the mass of COF-316 in step 3 is 12.88 mg, and the other steps and parameters are the same as in Examples 1 to 4; a COF-316 / Pt@TpBpy-COF composite material (mass ratio of 4:6) is obtained.

[0041] The following experiments were conducted to verify the beneficial effects of the present invention:

[0042] To investigate the photocatalytic decomposition effect of COF-316 / Pt@TpBpy-COF material, its visible light photocatalytic decomposition performance was tested using the following method. The test procedure was as follows: COF-316 / Pt@TpBpy-COF (10 mg) was used as the photocatalyst, and distilled water was used as the reaction solution. Under visible light, the photocatalytic decomposition efficiency of Pt@TpBpy-COF alone for hydrogen production from water was relatively low, only 96.0 μmol·h⁻¹. -1 ·g -1 Oxygen production was only 40.6 μmol·h⁻¹ -1 ·g -1 The COF-316 / Pt@TpBpy-COF composite material exhibited excellent photocatalytic water splitting performance, with a photocatalytic hydrogen production efficiency of 220.4 μmol·h⁻¹. -1 ·g -1 The oxygen production efficiency was 101.5 μmol·h⁻¹. -1 ·g -1 .

Claims

1. The application of a COF-316 / Pt@TpBpy-COF composite material in photocatalytic water splitting, characterized in that, The preparation method of the composite material is carried out according to the following steps: A heat-resistant glass tube was filled with an N,N-dimethylacetamide-DMA solution containing Pt NPs, 5,5-diamino-2,2-bipyridine, 1,3,5-trialdehyde phloroglucinol, and COF-316. Then, o-dichlorobenzene and DMA were added sequentially. The tube was sonicated at 35–45 kHz for 30–35 min, followed by the addition of 6 mol / L... -1 Acetic acid solution, circulated and degassed three times in liquid nitrogen, then sealed and cooled at 120°C. Heated in the medium for 72 hours, filtered, and washed several times with DMA and ethanol sequentially. Vacuum drying yields a reddish-brown powder, which is the COF-316 / Pt@TpBpy-COF composite material. The COF-316 forms an S-shaped heterojunction with TpBpy-COF-; The mass ratio of COF-316 to Pt@TpBpy-COF is 2:8.

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