A deuterated organic semiconductor photocatalyst, a preparation method thereof and a photocatalytic hydrogen production method

Abstract

The present application relates to a kind of deuterated organic semiconductor photocatalyst, it is deuterated polymer 2,4,5,6-tetrakis (9-carbazolyl) -m-dicyanobenzene.The beneficial effects of the present application are: the present application uses isotope substitution to modulate phonon effect and carrier dynamics process in photocatalytic process, provides a distinctive method for realizing efficient semiconductor photocatalysis.By deuterated carbazole replacing carbazole, deuterated carbazole-cyanobenzene conjugated polymer is synthesized, due to the replacement of hydrogen by deuterium, C-D bond stretching and bending energy is weakened, the phonon energy of catalyst is reduced, the non-radiative decay process of carrier is effectively inhibited, the carrier lifetime of deuterated sample is longer, the separation efficiency of photo-generated electron and hole is significantly improved, which leads to higher visible light catalytic decomposition of water hydrogen generation rate, to the effect of improving catalyst activity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalyst preparation, in particular to a deuterated organic semiconductor photocatalyst, a preparation method thereof and a photocatalytic hydrogen production method. BACKGROUND

[0002] Hydrogen energy, as a clean energy that can replace fossil fuels, is currently still dependent on fossil fuels for hydrogen production. Hydrogen energy, as a clean energy, is receiving more and more attention in today's world. Compared with traditional fossil fuels such as oil and natural gas, the only byproduct of hydrogen combustion is water, and no greenhouse gases such as carbon dioxide are produced, so it is considered an environmentally friendly and sustainable energy source. In order to achieve a green hydrogen production technology for sustainable development, photocatalytic water splitting for hydrogen production is considered one of the most ideal green hydrogen production technologies. Compared with traditional hydrogen production methods, photocatalytic hydrogen production technology has the advantages of low carbon emission, no pollution and wide raw material sources. Organic polymer semiconductors can be designed and controlled by molecules to achieve the optimization of specific performance, thereby realizing adjustable energy band structure, high light absorption coefficient, flexible processing and lower manufacturing cost, and are widely used as effective catalysts for photocatalytic decomposition of water. However, although organic polymer semiconductor photocatalysts have many advantages, due to their low dielectric constant, they have poor light carrier separation ability and strong exciton effect, which leads to low performance in catalyzing water decomposition for hydrogen production based on free carriers.

[0003] The low dielectric constant of polymer organic semiconductors causes the electron to easily couple with the local lattice, which sets a basic intrinsic limit for the migration and diffusion of the carriers in the polymer semiconductor. For most polymer organic semiconductors rich in hydrogen (H), compared with other elements, the deuterium (D) isotope substitution strategy, although only one more neutron, but the atomic mass is doubled, the vibration frequency of the chemical bond will change significantly, which is expected to induce changes in the phonon effect. For example, Wang et al. [9] fully deuterated Ir(ppy)3 molecules, due to the significant difference in atomic mass between D and H, resulting in a decrease in the stretching and bending energy of the Ir(ppy)3 molecule. When the C-H bond in the semiconductor photocatalyst is replaced by a C-D bond, the C-D bond will vibrate at a lower frequency (vibration frequency ratio is about 0.7) than the C-H bond, which is expected to cause changes in the phonon system within the polymer organic semiconductor photocatalyst, which is the basic unit of vibration, thereby having great potential to induce changes in electron-phonon interaction. Therefore, considering the electron-phonon interaction within the polymer organic semiconductor, designing the structure of the semiconductor photocatalyst based on the deuterium substitution strategy and regulating the electron-phonon interaction to improve the photocatalytic reaction performance of the polymer organic semiconductor photocatalyst is of great significance. SUMMARY

[0004] The technical problem to be solved by the present application is to study a deuterated organic semiconductor photocatalyst, a preparation method thereof and a photocatalytic hydrogen production method, so as to improve the migration and transportation efficiency of photo-generated carriers and improve the photocatalytic hydrogen production performance.

[0005] The technical scheme for solving the above technical problem is as follows:

[0006] The deuterated organic semiconductor photocatalyst is a deuterated polymer 2,4,5,6-tetrakis(9-carbazolyl)-m-benzene dicarbonitrile.

[0007] The beneficial effects of the present application are as follows: the present application uses isotope substitution to regulate phonons in the photocatalytic process, and provides a unique catalyst design and regulation method for realizing efficient semiconductor photocatalysis. By replacing carbazole with deuterated carbazole to synthesize deuterated carbazole-cyanophenyl conjugated polymer, it can be observed from the fluorescence measurement that the carrier lifetime of the deuterated sample is longer, the separation efficiency of photo-generated electrons and holes is obviously improved, and the variable temperature fluorescence spectrum data shows that the optical phonon energy is weakened and the Huang-Rhys factor S is enhanced. The internal conversion between the high vibration level of the ground state and the low vibration level of the excited state in the catalyst is the main driving force for the non-radiative decay of the carrier, and according to Fermi's golden rule, the internal conversion rate is negatively correlated with the Huang-Rhys factor S, so that the deuterium process inhibits the internal conversion process, that is, the non-radiative inactivation of electrons is reduced, the carrier lifetime is prolonged, thereby resulting in a higher visible light catalytic water decomposition hydrogen generation rate, and achieving the effect of improving the activity of the catalyst.

[0008] On the basis of the above technical scheme, the present application can also be improved as follows.

[0009] Another technical scheme of the present application is as follows:

[0010] A preparation method of a deuterated organic semiconductor photocatalyst comprises the following steps:

[0011] Preparation of deuterated 2,4,5,6-tetrakis(9-carbazolyl)-m-benzene dicarbonitrile:

[0012] Step 01, slowly add tetrahydrofuran solution to deuterated carbazole and sodium hydride, and stir;

[0013] Step 02, add tetrahydrofuran solution of tetrafluoro-m-benzene dicarbonitrile, and stir;

[0014] Step 03, add deionized water to the reaction mixture;

[0015] Step 04, concentrate the obtained mixture under reduced pressure, and wash with deionized water and ethanol to obtain a crude product;

[0016] Step 05, the crude product is purified by recrystallization to obtain deuterated 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile;

[0017] Preparation of deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile;

[0018] Step 06, deuterated 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile is dissolved in anhydrous chloroform to obtain a monomer solution;

[0019] Step 07, the monomer solution is added dropwise to a mixed solution of anhydrous ferric chloride and anhydrous chloroform;

[0020] Step 08, stirring, after stirring is completed, methanol is added, stirring, the obtained product is washed with hydrochloric acid;

[0021] Step 09, filtration, washing with deionized water;

[0022] Step 10, purification;

[0023] Step 11, drying, to obtain deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile.

[0024] Further, step 01 is carried out at room temperature in an argon atmosphere.

[0025] Further, in step 05, the crude product is passivated by recrystallization with cyclohexane or dichloromethane.

[0026] Further, in step 10, the product is purified by Soxhlet extraction: tetrahydrofuran, methanol are sequentially added to the product for purification.

[0027] Another technical solution of the present application is as follows:

[0028] A method for photocatalytic hydrogen production, using the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile prepared as described above as a photocatalyst for photocatalytic hydrogen production.

[0029] Further, the photocatalytic hydrogen production includes the following steps: placing the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile in a beaker, adding pure water and triethanolamine; placing the beaker in an ultrasonic instrument for ultrasonic treatment, so that the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile is effectively dispersed in the liquid; pouring the liquid into a reactor containing water to be decomposed, and carrying out photocatalytic hydrogen production.

[0030] Further, the reaction temperature in the reactor is 10℃, a xenon lamp light source is used to irradiate the solution in the reactor, the power of the xenon lamp light source is 15W and the wavelength of the light is greater than 420nm, and the solution in the reactor is stirred at a stirring rate of 250rpm. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 XRD pattern of poly-4CzIPN and D-poly-4CzIPN;

[0032] Figure 2 FTIR pattern of poly-4CzIPN and D-poly-4CzIPN;

[0033] Figure 3 UV-vis-DRS pattern of poly-4CzIPN and D-poly-4CzIPN;

[0034] Figure 4 Tacu pattern of poly-4CzIPN and D-poly-4CzIPN;

[0035] Figure 5 Photoluminescence (PL) pattern of poly-4CzIPN and D-poly-4CzIPN;

[0036] Figure 6 Transient fluorescence lifetime curve plot of the photocatalytic material;

[0037] Figure 7 Temperature dependent photoluminescence spectra plot of poly-4CzIPN and D-poly-4CzIPN samples in the temperature range from 4.4 K to 300 K;

[0038] Figure 8 Hydrogen production plot of poly-4CzIPN and D-poly-4CzIPN. DETAILED DESCRIPTION

[0039] The principles and features of the present application are described below in connection with the attached drawings, which are given as non-limiting examples only.

[0040] As shown in Figures 1-8 Figure 1, an embodiment of the present application is a deuterated organic semiconductor photocatalyst, which is a deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3- benzenedicarbonitrile.

[0041] The present application uses isotope substitution to modulate phonons in photocatalytic processes, providing a unique catalyst design method for achieving efficient semiconductor photocatalysis. By deuterating the synthesis of a deuterated carbazole-cyanophenyl conjugated polymer, it can be observed from fluorescence measurements that the carrier lifetime of the deuterated sample is longer, significantly improving the separation efficiency of photo-generated electrons and holes, and the variable temperature fluorescence spectrum data shows that the optical phonon energy is weakened and the Huang-Rhys factor S is enhanced. The internal conversion between the high vibrational level of the ground state and the low vibrational level of the excited state in the catalyst is the main driving force for the non-radiative decay of the carrier, and according to Fermi's golden rule, the internal conversion rate is negatively correlated with the Huang-Rhys factor S, so the deuteration process inhibits the internal conversion process, that is, the non-radiative inactivation of electrons is reduced, the carrier lifetime is prolonged, and thus a higher visible light catalytic water decomposition hydrogen generation rate is achieved, achieving the effect of improving the activity of the catalyst.

[0042] Embodiment 2 of the present application is a preparation method of a deuterated organic semiconductor photocatalyst, comprising the following steps:

[0043] Preparation of deuterated 2,4,5,6-tetra(9-carbazolyl)-m-benzene dicarbonitrile:

[0044] Step 01, slowly add tetrahydrofuran solution to deuterated carbazole and sodium hydride, and stir;

[0045] Step 02, add tetrahydrofuran solution of tetrafluoro-m-benzene dicarbonitrile, and stir;

[0046] Step 03, add deionized water to the reaction mixture;

[0047] Step 04, concentrate the obtained mixture under reduced pressure, and wash with deionized water and ethanol to obtain a crude product;

[0048] Step 05, purify the crude product by recrystallization to obtain deuterated 2,4,5,6-tetra(9-carbazolyl)-m-benzene dicarbonitrile;

[0049] Preparation of deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-m-benzene dicarbonitrile;

[0050] Step 06, dissolve deuterated 2,4,5,6-tetra(9-carbazolyl)-m-benzene dicarbonitrile in anhydrous chloroform to obtain a monomer solution;

[0051] Step 07, add the monomer solution dropwise to a mixed solution of anhydrous ferric chloride and anhydrous chloroform;

[0052] Step 08, stir, and after stirring is completed, add methanol, stir, and wash the obtained product with hydrochloric acid;

[0053] Step 09, filter and wash with deionized water;

[0054] Step 10, purification;

[0055] Step 11, drying, to obtain deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile.

[0056] Embodiment 3 of the present application is a preparation method of a deuterated organic semiconductor photocatalyst, based on Embodiment 2 or, step 01 is carried out at room temperature in an argon atmosphere.

[0057] Embodiment 4 of the present application is a preparation method of a deuterated organic semiconductor photocatalyst, based on Embodiment 3, in step 05, the crude product is passivated by recrystallization in cyclohexane or dichloromethane.

[0058] Embodiment 5 of the present application is a preparation method of a deuterated organic semiconductor photocatalyst, based on Embodiment 4, in step 10, the product is purified by Soxhlet extraction: tetrahydrofuran, methanol are sequentially added to the product.

[0059] Embodiment 6 of the present application is a photocatalytic hydrogen production method, using the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile prepared as described above as a photocatalyst for photocatalytic hydrogen production.

[0060] Embodiment 7 of the present application is a photocatalytic hydrogen production method, based on Embodiment 6, the photocatalytic hydrogen production includes the following steps: the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile is placed in a beaker, pure water and triethanolamine are added; the beaker is placed in an ultrasonic instrument for ultrasonic treatment, so that the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile is effectively dispersed in the liquid; the liquid is poured into a reactor containing water to be decomposed, and photocatalytic hydrogen production is carried out.

[0061] Embodiment 8 of the present application is a photocatalytic hydrogen production method, based on Embodiment 7, the reaction temperature in the reactor is 10℃, a xenon lamp light source is used to irradiate the solution in the reactor, the power of the xenon lamp light source is 15W and the wavelength of the light is greater than 420nm, and the solution in the reactor is stirred at a stirring rate of 250rpm. Specific embodiments

[0063] Preparation of deuterated 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile (D-4CzIPN);

[0064] Step 01, under an argon atmosphere at room temperature, 10ml of tetrahydrofuran solution is slowly added to 600mg of sodium hydride (60% in oil) and 1670mg, 10.0mmmol of deuterated carbazole, and stirred for 30 minutes;

[0065] Step 02, 400 mg of tetrachloro isophthalonitrile dissolved in 10 ml of tetrahydrofuran was added, stirred at room temperature under argon atmosphere for 12 hours;

[0066] Step 03, 2 ml of deionized water was added to the reaction mixture to quench the excess sodium hydride;

[0067] Step 04, the resulting mixture was concentrated under reduced pressure and the resulting crude product was washed with deionized water and ethanol;

[0068] Step 05, finally purified by recrystallization in cyclohexane or dichloromethane to obtain deuterated 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile (D-4CzIPN);

[0069] Preparation of deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile (D-poly-4CzIPN);

[0070] Step 06, under argon atmosphere, deuterated 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile was dissolved in 50 ml of anhydrous chloroform to obtain a monomer solution;

[0071] Step 07, the monomer solution was added dropwise to a mixture of 322 mg of anhydrous iron chloride and 100 ml of anhydrous chloroform;

[0072] Step 08, the reaction mixture was stirred at room temperature for 72 hours, after stirring was complete, 50 ml of methanol was added, stirred for 1 h to quench the excess sodium hydride, the resulting product was washed with hydrochloric acid (12M) for 1 h;

[0073] Step 09, filtered and washed with deionized water;

[0074] Step 10, purified by Soxhlet extraction, tetrahydrofuran was added sequentially for 24 h, methanol for 48 h;

[0075] Step 11, dried at 80°C under vacuum atmosphere for 24 h to obtain deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile (D-poly-4CzIPN).

[0076] Comparative Example

[0077] Preparation of 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile (4CzIPN);

[0078] Step 01, 10 ml of tetrahydrofuran solution was slowly added to a mixture of 600 mg of sodium hydride (60% in oil) and 1670 mg, 10.0 mmol of carbazole at room temperature under argon atmosphere, stirred for 30 minutes;

[0079] Step 02, Add 400 mg of tetrachloro-p-phenylenedicyan solution dissolved in 10 ml of tetrahydrofuran, stir at room temperature under argon atmosphere for 12 hours;

[0080] Step 03, Add 2 ml of deionized water to the reaction mixture to quench the excess sodium hydride;

[0081] Step 04, Concentrate the resulting mixture under reduced pressure and wash the resulting crude product with deionized water and ethanol;

[0082] Step 05, Finally, purify by recrystallization in cyclohexane or dichloromethane to obtain 2,4,5,6-tetra(9-carbazolyl)-p-phenylenedicyan (4CzIPN);

[0083] Preparation of polymer 2,4,5,6-tetra(9-carbazolyl)-p-phenylenedicyan (poly-4CzIPN);

[0084] Step 06, Dissolve 2,4,5,6-tetra(9-carbazolyl)-p-phenylenedicyan in 50 ml of anhydrous chloroform under argon atmosphere to obtain a monomer solution;

[0085] Step 07, Add the monomer solution dropwise to a mixture of 322 mg of anhydrous iron chloride and 100 ml of anhydrous chloroform;

[0086] Step 08, Stir the reaction mixture at room temperature for 72 hours, after stirring is complete, add 50 ml of methanol, stir for 1 h to quench the excess sodium hydride, wash the resulting product with hydrochloric acid (12M) for 1 h;

[0087] Step 09, Filter and wash with deionized water;

[0088] Step 10, Purify using Soxhlet extraction, sequentially add tetrahydrofuran for 24 h, and methanol for 48 h;

[0089] Step 11, Dry at 80°C under vacuum atmosphere for 24 h to obtain polymer 2,4,5,6-tetra(9-carbazolyl)-p-phenylenedicyan (poly-4CzIPN).

[0090] Photocatalytic hydrogen production was performed in a Labsolar-6A instrument. 10 mg of the above prepared deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile (D-poly-4CzIPN) catalyst was weighed into a beaker, 45 mL of pure water was added, 5 mL of triethanolamine was added as a hole sacrificial agent, and 3% H2PtCl6 was added. The beaker containing the sample was placed in an ultrasonic instrument for 5 minutes to effectively disperse the catalyst in the liquid. After ultrasonic, the mixture was poured into the reactor, and the instrument was prepared, and then the photocatalytic hydrogen production was carried out. The reaction temperature was maintained at 10°C, the xenon lamp light source power was 15W and the light wave wavelength was greater than 420nm, and the stirring rate of the reactor was 250rpm.

[0091] As shown in FIG. 1, both poly-4CzIPN and D-poly-4CzIPN were observed to have two relatively wide characteristic diffraction peaks at 2θ = 8° and 24.6°, indicating that the introduction of deuterium did not cause significant changes in the structure of the polymer. Figure 1 As shown in FIG. 2, the Fourier transform infrared spectrum shows that poly-4CzIPN and D-poly-4CzIPN exhibit multiple typical signals in the range of 1700 cm -1 to 1200 cm -1 , which can be attributed to the skeletal vibration of the aromatic ring; the signal at 2236 cm -1 is attributed to the C≡N stretching mode. Compared with poly-4CzIPN, D-poly-4CzIPN exhibits a 20-100 cm -1 shift in the characteristic peaks at 1225 cm -1 , 1454 cm -1 and 1611 cm -1 , indicating that C-D bond substitution causes significant changes in vibration. Most notably, the stretching vibration of C-H bond at 3050 cm -1 and the bending vibration at 741 cm -1 move to 2278 cm -1 and 578 cm -1 , respectively, after deuteration. Through wavelength and energy conversion, the shift of typical C-H bond at 3050 cm -1 and 741 cm-1 corresponds to an energy change of 2.2 kcal / mol and 0.5 kcal / mol, respectively. Therefore, deuterium substitution leads to a decrease in the overall stretching and bending vibration energy of poly-4CzIPN, indicating a decrease in phonon energy of lattice vibration energy.

[0092] As shown in FIG. 3, the Fourier transform infrared spectrum shows that poly-4CzIPN and D-poly-4CzIPN exhibit multiple typical signals in the range of 1700 cm -1 to 1200 cm -1 , which can be attributed to the skeletal vibration of the aromatic ring; the signal at 2236 cm -1 is attributed to the C≡N stretching mode. Compared with poly-4CzIPN, D-poly-4CzIPN exhibits a 20-100 cm -1 shift in the characteristic peaks at 1225 cm -1 , 1454 cm -1 and 1611 cm -1 , indicating that C-D bond substitution causes significant changes in vibration. Most notably, the stretching vibration of C-H bond at 3050 cm -1 and the bending vibration at 741 cm -1 move to 2278 cm -1 and 578 cm -1 , respectively, after deuteration. Through wavelength and energy conversion, the shift of typical C-H bond at 3050 cm -1 and 741 cm-1 corresponds to an energy change of 2.2 kcal / mol and 0.5 kcal / mol, respectively. Therefore, deuterium substitution leads to a decrease in the overall stretching and bending vibration energy of poly-4CzIPN, indicating a decrease in phonon energy of lattice vibration energy. Figure 2 As shown in FIG. 4, the Fourier transform infrared spectrum shows that poly-4CzIPN and D-poly-4CzIPN exhibit multiple typical signals in the range of 1700 cm -1 to 1200 cm -1 , which can be attributed to the skeletal vibration of the aromatic ring; the signal at 2236 cm -1 is attributed to the C≡N stretching mode. Compared with poly-4CzIPN, D-poly-4CzIPN exhibits a 20-100 cm -1 shift in the characteristic peaks at 1225 cm -1 , 1454 cm -1 and 1611 cm -1 , indicating that C-D bond substitution causes significant changes in vibration. Most notably, the stretching vibration of C-H bond at 3050 cm -1 and the bending vibration at 741 cm -1 move to 2278 cm -1 and 578 cm -1 , respectively, after deuteration. Through wavelength and energy conversion, the shift of typical C-H bond at 3050 cm -1 and 741 cm-1 corresponds to an energy change of 2.2 kcal / mol and 0.5 kcal / mol, respectively. Therefore, deuterium substitution leads to a decrease in the overall stretching and bending vibration energy of poly-4CzIPN, indicating a decrease in phonon energy of lattice vibration energy.

[0093] Figure 3As shown in the figure, it can be clearly seen that compared with poly-4CzIPN, the absorption wavelength of D-poly-4CzIPN has a blue shift, and the absorption intensity is slightly weakened, which is consistent with the apparent color change of the catalyst. The color of poly-4CzIPN is reddish brown, and the color of D-poly-4CzIPN after deuterium replaces hydrogen is yellowish brown.

[0094] like Figure 4 As shown, it can be seen that the band gaps of poly-4CzIPN and D-poly-4CzIPN are 2.26eV and 2.28eV respectively. The substitution of deuterium has a certain influence on the energy band structure of the catalyst.

[0095] like Figure 5 As shown in the figure, it can be clearly seen that D-poly-4CzIPN has a higher fluorescence intensity. This is because the lower vibration of the CD bond in D-poly-4CzIPN effectively prevents the non-radiative decay process, thereby significantly improving the radiative fluorescence efficiency.

[0096] like Figure 6 As shown, the fluorescence lifetime of poly-4CzIPN is 2.25ns, and that of D-poly-4CzIPN is 2.45ns. The deuterium substitution strategy extends the lifetime of photogenerated carriers. This extension of fluorescence lifetime is because deuterium substitution significantly reduces the proton stretching frequency and phonon energy, requiring a higher vibrational quantum to bridge the band gap between the excited and ground states, resulting in a longer relaxation time for excited-state electrons to return to the ground state.

[0097] like Figure 7 As shown in Figure 2, it can be observed that the temperature-induced fluorescence intensity change in D-poly-4CzIPN is more obvious than that in poly-4CzIPN. The PL line width at different temperatures is extracted from the temperature-dependent fluorescence spectrum and fitted by equation (1) to obtain the Huang-Rys factor to evaluate the electron-phonon coupling strength:

[0098] The fitting results show that the Huang-Rys factor and phonon energy in the poly-4CzIPN are 3.3 and 94.73 meV, respectively, and the Huang-Rys factor and phonon energy in the D-poly-4CzIPN are 5.6 and 72.89 meV, respectively. The lower phonon energy in the poly-D-4CzIPN is the result of the weakening of the vibration caused by the substitution of C-D bonds for C-H bonds, which is consistent with the FTIR results. The internal conversion between the high vibration level of the ground state and the low vibration level of the excited state in the catalyst is the main driving force for the non-radiative decay of carriers, and according to the Fermi golden rule, the internal conversion rate is negatively correlated with the Huang-Rys factor S, so the enhanced Huang-Rys factor after the deuteration process means that the internal conversion process is inhibited, that is, the non-radiative inactivation of electrons is reduced, the carrier lifetime is prolonged, thereby resulting in a higher visible light catalytic water decomposition hydrogen generation rate, achieving the effect of improving the activity of the catalyst.

[0099] As shown in Figure 8 , it can be observed from the figure that the hydrogen production capacity of the D-poly-4CzIPN is stronger. The hydrogen production rate of the D-poly-4CzIPN is 2254 μmol·g -1 ·h -1 , and the hydrogen production rate of the poly-4CzIPN is 1816 μmol·g -1 ·h -1 .

[0100] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a deuterated organic semiconductor photocatalyst, characterized by, comprising the steps of: preparing deuterated 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile: step 01, slowly adding a tetrahydrofuran solution to deuterated carbazole and sodium hydride, stirring; step 02, adding a tetrahydrofuran solution of tetrafluoro-1,3-benzenedicarbonitrile, stirring; step 03, adding deionized water to the reaction mixture; step 04, concentrating the resulting mixture under reduced pressure, washing with deionized water and ethanol to obtain a crude product; step 05, purifying the crude product by recrystallization to obtain deuterated 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile; preparing deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile; step 06, dissolving deuterated 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile in anhydrous chloroform to obtain a monomer solution; step 07, adding the monomer solution dropwise to a mixed solution of anhydrous ferric chloride and anhydrous chloroform; step 08, stirring, after stirring is completed, adding methanol, stirring, washing the resulting product with hydrochloric acid; step 09, filtering, washing with deionized water; step 10, purifying; step 11, drying to obtain deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile.

2. The method for preparing a deuterated organic semiconductor photocatalyst according to claim 1, characterized in that: The step 01 is carried out at room temperature in an argon atmosphere.

3. The method according to claim 2, wherein the deuterated organic semiconductor photocatalyst is prepared by the following steps: (1) preparing a deuterated organic semiconductor photocatalyst precursor; (2) deuterating the deuterated organic semiconductor photocatalyst precursor to obtain the deuterated organic semiconductor photocatalyst. In the step 05, the crude product is passivated by recrystallization with cyclohexane or dichloromethane.

4. The method according to claim 3, wherein the deuterated organic semiconductor photocatalyst is prepared by the following steps: (1) preparing a deuterated organic semiconductor photocatalyst precursor; (2) deuterating the deuterated organic semiconductor photocatalyst precursor to obtain the deuterated organic semiconductor photocatalyst. In the step 10, the product is purified by Soxhlet extraction by sequentially adding tetrahydrofuran and methanol.

5. A deuterated organic semiconductor photocatalyst, characterized by, Deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile prepared by any one of the preparation methods according to claims 1 to 4.

6. A method for photocatalytic hydrogen production, characterized by, Using a deuterated organic semiconductor photocatalyst according to claim 5, or using deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile prepared by any one of the preparation methods according to claims 1 to 4 as a photocatalyst for photocatalytic hydrogen production.

7. The photocatalytic hydrogen production method according to claim 6, wherein The photocatalytic hydrogen production comprises the steps of: placing deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile in a beaker, adding pure water and triethanolamine; placing the beaker in an ultrasonic instrument to ultrasonically disperse the deuterated polymer 2,4,5,6-tetra(9-carbazolyl)-1,3-benzenedicarbonitrile in the liquid; pouring the liquid into a reactor containing water to be decomposed, and carrying out photocatalytic hydrogen production. 8.The method according to claim 7, wherein, The reaction temperature in the reactor is 10°C, a xenon lamp light source is used to irradiate the solution in the reactor, the power of the xenon lamp light source is 15W and the light wave wavelength is greater than 420nm, and the solution in the reactor is stirred at a stirring rate of 250rpm.

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