Preparation of tpbd-tp tapt composite material and application in hydrogen production by photolysis of water

Abstract

The application relates to preparation of a TpBD-TpTAPT composite material and application of the composite material in photocatalytic decomposition of water to produce hydrogen. The application aims to solve the problems of low light utilization rate and low hydrogen production efficiency of existing single COF materials, i.e. TpBD and TpTAPT photocatalytic water decomposition hydrogen production materials, and provides a novel preparation method of a TpBD-TpTAPT composite material. First, 4,4'-diaminobiphenyl and 1,3,5-triformylphloroglucinol, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 1,3,5-triformylphloroglucinol are respectively dispersed into a mixed solution of 1.75ml of mesitylene and acetic acid (6:1) to prepare TpBD and TpTAPT COF precursors through solvent dispersion; and then the obtained two kinds of COF precursors are compounded through a solvothermal method under the condition of heating at 120 DEG C for 72h to obtain the TpBD-TpTAPT composite material. The preparation process is simple and effective, reagent consumption is low, and the yield is high; and the photocatalyst provided by the application can effectively improve the problem of low photocatalytic water decomposition hydrogen production efficiency. The application is applied to the field of photocatalytic decomposition of water to produce hydrogen, and experiments show that the composite material has excellent photocatalytic decomposition of water to produce hydrogen performance, and the water decomposition hydrogen production rate can reach 34.91mmol.h ‑1 ·g ‑1 under visible light irradiation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photocatalytic materials, and particularly relates to a preparation method of TpBD-TpTAPT composite material and application of the TpBD-TpTAPT composite material in water splitting for hydrogen production. BACKGROUND

[0002] With the rapid development of economy and the continuous increase of population, the dependence of human society development on energy is increasing day by day, and the rapid consumption of traditional fossil energy has caused a severe energy crisis and led to serious environmental pollution and ecological damage. Developing clean and renewable energy is particularly important for solving the energy and environmental problems worldwide. Hydrogen energy, as a potential energy carrier, has the advantages of green, no pollution, small density and easy transportation. Therefore, water splitting for hydrogen production through solar energy is undoubtedly an ideal conversion approach. Developing efficient catalysts, maximizing the use of visible light and improving the efficiency of electron-hole separation are still the keys in this field.

[0003] Covalent organic framework materials (COFs) are porous crystalline materials formed by C, B, O, N and Si light elements through covalent bonds, which have the advantages of light mass, low density, high specific surface area, regular structure, uniform pore, relatively stable structure and easy functional modification, so that COFs show a promising application prospect in gas storage and separation, catalysis, sensing, energy storage, photoelectric conversion and other fields. However, single-component COFs photocatalysts have a serious problem of photo-generated electron-hole recombination, which limits the further improvement of the hydrogen production activity of COFs photocatalysts. Therefore, developing a composite material with high efficiency for photocatalytic water splitting has become a research hotspot.

[0004] Compared with the previously reported inorganic-organic heterojunctions, the heterojunctions formed by COFs are more closely combined and more effectively promote the separation of charges, the recombination rate of photo-generated charges is greatly reduced, the charge carriers have a longer life, thereby effectively improving the photocatalyst activity, improving the effectiveness of charge transport, and being more conducive to the application of the material in photocatalytic function. SUMMARY

[0005] The application aims to solve the problem of low efficiency of photocatalytic water splitting for hydrogen production of existing materials, and provides a preparation method of TpBD-TpTAPT composite material and application of the TpBD-TpTAPT composite material in water splitting for hydrogen production.

[0006] The preparation method of the TpBD-TpTAPT composite material of the application is completed according to the following steps:

[0007] Step 1: 16.56 mg (0.09 mmol) of 4,4'-diaminobiphenyl and 12.6 mg (0.06 mmol) of 1,3,5-triformylphloroglucinol were added into a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid (6:1), and ultrasonic treatment was performed at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpBD COF precursor;

[0008] Step 2: 14.17 mg (0.04 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 8.6 mg (0.04 mmol) of 1,3,5-triformylphloroglucinol were added into a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid (6:1), and ultrasonic treatment was performed at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpTAPT COF precursor;

[0009] Step 3: The TpBD and TpTAPT COF precursors obtained in steps 1 and 2 were added into a heat-resistant glass tube, ultrasonic treatment was performed at an ultrasonic frequency of 40 KHz for 30-35 min, and degassing was performed by three freeze-thaw cycles in a liquid nitrogen bath, and then the mixture was sealed and heated at 120℃ for 72 h, and then filtration was performed and the mixture was washed several times with tetrahydrofuran, and then drying was performed to obtain a TpBD-TpTAPT (molar mass ratio of 6:4) composite material.

[0010] The molar ratio of the 4,4'-diaminobiphenyl and 1,3,5-triformylphloroglucinol in step 1 was 3:2;

[0011] The molar ratio of the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 1,3,5-triformylphloroglucinol in step 2 was 1:1;

[0012] The volume ratio of the mesitylene and acetic acid in steps 1 and 2 was 6:1;

[0013] The concentration of the acetic acid used in steps 1 and 2 was 3 mol·L -1 ;

[0014] The yield of the TpBD COF and the TpTAPT COF in step 3 under the same reaction conditions was about 80%, and by controlling the dosing amount of different raw materials, the molar ratio of the TpBD and the TpTAPT in the composite material was 8:2; 7:3; 6:4; 5:5; 4:6; 3:7;

[0015] The application provides an application of the TpBD-TpTAPT composite material in photocatalytic decomposition of water to produce hydrogen:

[0016] To investigate the TpBD-TpTAPT material catalytic decomposition of water hydrogen production effect, the following method for visible light photocatalytic decomposition of water hydrogen production performance test. The test process is as follows: TpBD-TpTAPT (10mg) as photocatalyst, L-ascorbic acid sodium (100mg) as the sacrificial agent, PBS buffer solution (50mL, 0.1mol·L -1 , pH = 7) as the reaction liquid, ultrasonic 30min makes it form uniform suspension and with xenon lamp (λ>420nm) as light source test.

[0017] The beneficial effects of the present application:

[0018] The present application adopts solvothermal method, respectively with 4,4'-diaminobiphenyl, 2,4,6-tri (4-aminophenyl) -1,3,5-triazine and 1,3,5-trialdehyde m-phenol as raw material, successfully synthesized TpBD and TpTAPT, but the material in the visible light decomposition of water hydrogen production efficiency is low only 4.25 and 2.21mmol·h -1 ·g -1 Therefore, the application will TpBD and TpTAPT in the precursor state composite, synthesis of a new composite material TpBD-TpTAPT, the material effectively improves the water hydrogen production performance, TpBD-TpTAPT composite material of water hydrogen production efficiency is highest 34.91mmol·h -1 ·g -1 . BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is X-ray powder diffraction pattern of TpBD-TpTAPT material;

[0020] Figure 2 TpBD-TpTAPT material infrared spectrum;

[0021] Figure 3 Mott-Schottky test diagram of TpBD-TpTAPT material;

[0022] Figure 4 UV-vis DRS test diagram of TpBD-TpTAPT material;

[0023] Figure 5 Band structure diagram of TpBD-TpTAPT material;

[0024] Figure 6 TpBD-TpTAPT material photocatalytic decomposition of water hydrogen production performance diagram. DETAILED DESCRIPTION

[0025] The application will be further described by the following examples, which only illustrate the method of the application and do not limit the scope of the application.

[0026] Example 1: The preparation of a TpBD-TpTAPT composite material in this embodiment is completed according to the following steps:

[0027] Step 1: 16.56 mg (0.09 mmol) of 4,4'-diaminobiphenyl and 12.6 mg (0.06 mmol) of 1,3,5-triformylphloroglucinol are added to a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid (6:1), and then ultrasonic treatment is performed at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpBD COF precursor;

[0028] Step 2: 14.17 mg (0.04 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 8.6 mg (0.04 mmol) of 1,3,5-triformylphloroglucinol are added to a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid (6:1), and then ultrasonic treatment is performed at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpTAPT COF precursor;

[0029] Step 3: The TpBD and TpTAPT COF precursors obtained in steps 1 and 2 are added to a heat-resistant glass tube, ultrasonic treatment is performed at an ultrasonic frequency of 40 KHz for 30-35 min, and degassing is performed by three freeze-thaw cycles in a liquid nitrogen bath, and then the mixture is sealed and heated at 120°C for 72 h, filtered, washed several times with tetrahydrofuran, and dried to obtain a TpBD-TpTAPT (molar mass ratio of 6:4) composite material.

[0030] Example 2: The difference between this embodiment and example 1 is that the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4,4'-diaminobiphenyl in step one is 7.08 mg (0.02 mmol) and 22.08 mg (0.12 mmol), respectively, and the other steps and parameters are the same as in example 1; and a TpBD-TpTAPT (molar mass ratio of 8:2) composite material is obtained.

[0031] Example 3: The difference between this embodiment and example 1 or 2 is that the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4,4'-diaminobiphenyl in step one is 10.63 mg (0.03 mmol) and 19.32 mg (0.105 mmol), respectively, and the other steps and parameters are the same as in example 1 or 2; and a TpBD-TpTAPT (molar mass ratio of 7:3) composite material is obtained.

[0032] Example 2: The difference between this embodiment and Example 1 is that the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4,4'-diaminobiphenyl in step one is 17.72 mg (0.05 mmol) and 13.8 mg (0.075 mmol), respectively, and other steps and parameters are the same as those in Example 1; to obtain TpBD-TpTAPT (molar mass ratio of 5:5) composite material.

[0033] Example 4: The difference between this embodiment and Examples 1 to 3 is that the mass of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4,4'-diaminobiphenyl is 21.26 mg (0.06 mmol) and 11.04 mg (0.06 mmol), respectively, and other steps and parameters are the same as those in Examples 1 to 3; to obtain TpBD-TpTAPT (molar mass ratio of 4:6) composite material.

[0034] To verify the beneficial effects of the present application, the following tests were conducted:

[0035] I. X-ray diffraction (XRD) analysis: The sample is irradiated with X-rays of sufficient energy, and the substances in the sample are excited to produce secondary fluorescent X-rays. The qualitative analysis of the compound is carried out by the position of the diffraction angle (peak position). It is determined that the crystal form of the TpBD-TpTAPT composite material provided by the present application is consistent with the single crystal diffraction simulation, and has the characteristic peaks possessed by the monomer.

[0036] II. Infrared spectrum test: The molecular structure of the compound is determined by infrared spectrum, and the characteristic functional groups are determined by comparing the spectrum of the standard substance, which assists the XRD test to determine that the product has been successfully synthesized.

[0037] III. Mott-Schottky test: The flat band potential of the semiconductor is determined by coating the conductive glass of the semiconductor sample using the electrochemical workstation, and then the conduction band position of the semiconductor is calculated, and the valence band position of the semiconductor is calculated in combination with the UV-vis DRS test.

[0038] IV. UV-vis DRS test: The information of the substance is obtained by using the reflection of light on the surface of the substance. The UV-vis DRS test is carried out on the semiconductor, and under the excitation of light, charge transfer occurs, electrons absorb energy, and photons are transferred from the donor to the acceptor, resulting in an absorption spectrum in the ultraviolet region. The diffuse reflectance spectrum can be obtained by simultaneously detecting the specular reflectance and diffuse reflectance of the solid powder sample, and the band gap of the semiconductor can be obtained by calculating the diffuse reflectance spectrum, and the energy band structure of the semiconductor can be obtained in combination with the Mott-Schottky test.

Claims

1. A method for preparing a TpBD-TpTAPT composite material for photocatalytic decomposition of water to produce hydrogen, characterized by, The preparation method of the composite material is carried out according to the following steps: Step 1: 16.56 mg of 4,4'-diaminobiphenyl and 12.6 mg of 1,3,5-triformylphloroglucinol are added into a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid, and ultrasonic treatment is carried out at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpBD COF precursor, wherein the volume ratio of the mesitylene to the acetic acid is 6:1; Step 2: 14.17 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 8.6 mg of 1,3,5-triformylphloroglucinol are added into a test tube, followed by adding 1.75 ml of a mixed solution of mesitylene and acetic acid, and ultrasonic treatment is carried out at an ultrasonic frequency of 40 KHz for 30-35 min to obtain a TpTAPT COF precursor, wherein the volume ratio of the mesitylene to the acetic acid is 6:1; Step 3: The TpBD and TpTAPT COF precursors obtained in steps 1 and 2 are added into a heat-resistant glass tube, ultrasonic treatment is carried out at an ultrasonic frequency of 40 KHz for 30-35 min, and degassing is carried out by three freeze-thaw cycles in a liquid nitrogen bath, and then the mixture is sealed and heated at 120 DEG C for 72 h, filtered, washed with tetrahydrofuran for several times, and dried to obtain a TpBD-TpTAPT composite material, wherein the molar ratio of the TpBD-TpTAPT composite material is 6:

4.

2. The method for preparing a TpBD-TpTAPT composite material for photocatalytic decomposition of water to produce hydrogen according to claim 1, characterized in that, The concentration of acetic acid used in step 1 and step 2 is 3 mol L -1 .

Images