A method for reducing schottky barrier of cofs photocatalyst and pt cocatalyst interface
By immobilizing modified small-molecule Pt nanoparticles in the pores of COFs, the problem of high Schottky barrier at the interface between COFs and Pt cocatalysts was solved, achieving efficient photogenerated electron transfer and stable photocatalytic water splitting for hydrogen production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QILU UNIVERSITY OF TECHNOLOGY (SHANDONG ACADEMY OF SCIENCES)
- Filing Date
- 2023-10-24
- Publication Date
- 2026-06-23
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to a method for reducing the Schottky barrier at the interface between COFs photocatalysts and Pt cocatalysts, belonging to the field of porous organic materials and photocatalysis. Background Technology
[0002] The energy crisis and environmental pollution have become the most intractable global problems. Photocatalytic hydrogen production, which converts solar energy into chemical fuels, has emerged as a potential and effective technology for obtaining new energy sources. Covalent organic frameworks (COFs) are highly crystalline porous organic polymer materials composed of organic monomers linked by covalent bonds. They possess advantages such as low density, large specific surface area, high porosity, and highly tunable chemical structure, exhibiting properties similar to n-type organic semiconductors. As an excellent photocatalyst, they have attracted widespread attention. However, the photocatalytic efficiency of single-component COFs remains relatively low, partly due to the rapid recombination of photogenerated charges. With increasing government requirements for low energy consumption and low pollution, and growing public awareness of environmental protection, developing green and environmentally friendly COF solar photocatalytic hydrogen evolution technology to further meet the practical applications of COF materials has become an urgent problem to be solved in the COF materials field. Various COF structures have been used in photocatalytic hydrogen evolution research; however, improving their photocatalytic hydrogen evolution performance can only be achieved by modifying the COF framework structure, requiring the design of complex organic synthesis processes, which significantly increases costs. Therefore, it is urgent and of practical significance to develop a simple, low-cost method for improving the photocatalytic hydrogen evolution performance of COFs that is suitable for large-scale production.
[0003] Supported catalysts are an effective way to suppress carrier recombination. They can not only capture electrons but also provide effective proton reduction sites, thereby significantly improving the photocatalytic hydrogen evolution activity. For example, G. Xuan et al. synthesized Pd nanoparticles by assembling palladium (Pd) nanoparticles into covalent organic framework materials. 0 / TpPa-1-COF photocatalyst is used for photocatalytic water splitting to produce hydrogen (Int.J.Hydrogen Energy 2019, 44(23): 11872-11876), and has good performance in photocatalytic water splitting to produce hydrogen.
[0004] Traditional COFs commonly use photodeposition to load Pt nanoparticles as cocatalysts to accelerate the hydrogen evolution reaction rate. However, this method directly constructs the Schottky interface between COFs and Pt. Due to the large work function of Pt, the conduction and valence bands of COFs bend upwards, forming a high Schottky barrier. This severely hinders the transport of photogenerated electrons from the COFs valence band to the Pt nanoparticles. Furthermore, photogenerated electrons transported to Pt also flow back due to the upward bending of the COFs valence band, causing severe photoelectron-hole recombination. Developing low-cost and easy-to-operate strategies to reduce the Schottky barrier height has become an urgent problem to be solved in the field of COF photocatalytic materials. Currently, there are no reports on solutions to this problem in the field of COF photocatalytic hydrogen evolution. Summary of the Invention
[0005] To address the shortcomings of existing technologies, especially the problem of high Schottky barriers at the interface between existing COFs and Pt, this invention provides a method for reducing the Schottky barrier at the interface between COFs photocatalysts and Pt cocatalysts.
[0006] This invention leverages the advantages of high crystallinity and highly tunable pore size and pore environment of COFs. By modifying the surface of Pt nanoparticles with small molecules and adjusting the size of the Pt nanoparticles, and targeting the formation principle of the Schottky barrier, a pore immobilization strategy of COFs is successfully developed to fix the surface-modified Pt nanoparticles into the pores. The surface-modified small molecules separate Pt and COFs, reducing the height of the Schottky barrier while promoting electron transfer. This develops a method to reduce the Schottky barrier at the COFs-Pt interface, which can be used as a photocatalyst for light energy conversion to achieve hydrogen production from water splitting. It can effectively avoid the cumbersome design of COFs monomers and is suitable for practical applications of COFs photocatalysis.
[0007] This invention is achieved through the following technical solution:
[0008] A method for reducing the Schottky barrier at the interface between COF photocatalysts and Pt co-catalysts includes the following steps:
[0009] 1) Preparation of surface-modified Pt nanoparticles
[0010] The mother liquor of chloroplatinic acid, the surface modifier and the reducing agent were mixed and the volume was adjusted to obtain a mixed solution. The mixed solution was subjected to a solvothermal reaction. After the reaction was completed, an aqueous solution of surface-modified Pt nanoparticles was obtained.
[0011] 2) Add COFs photocatalyst to the aqueous solution of surface-modified Pt nanoparticles, sonicate to mix evenly, stir at room temperature for adsorption and fixation, wash the product after the reaction to purify it, reduce the Schottky barrier height, and dry the purified product.
[0012] According to a preferred embodiment of the present invention, in step 1), the concentration of the chloroplatinic acid mother liquor is 40-60 mM. The chloroplatinic acid mother liquor is an aqueous solution of chloroplatinic acid.
[0013] According to a preferred embodiment of the present invention, in step 1), the surface modifier is one or a mixture of two or more of amino acids, sodium citrate, and polyvinylpyrrolidone.
[0014] According to a preferred embodiment of the present invention, in step 1), the reducing agent is sodium citrate or ethylene glycol.
[0015] According to a preferred embodiment of the present invention, in step 1), the concentration of chloroplatinic acid in the mixed solution is 0.5-3 mM.
[0016] According to a preferred embodiment of the present invention, in step 1), when the reducing agent is sodium citrate, water is used to make up the volume, water is used as the solvent, the concentration of the reducing agent in the mixed solution is 0.034-0.07 mmol / mL, and the concentration of the surface modifier is 0-2 mg / mL.
[0017] According to a preferred embodiment of the present invention, in step 1), when the reducing agent is ethylene glycol, ethylene glycol is used to make up the volume. Ethylene glycol acts as both a reducing agent and a solvent, and the concentration of the surface modifier in the mixed solution is 4-30 mg / mL.
[0018] According to a preferred embodiment of the present invention, in step 1), the solvothermal reaction temperature is 90-120°C and the reaction time is 10-120 min.
[0019] According to a preferred embodiment of the present invention, in step 1), the aqueous solution of surface-modified Pt nanoparticles is directly used for curing in step 2), and the concentration of the aqueous solution of surface-modified Pt nanoparticles is 0.8-1.2 mM.
[0020] According to a preferred embodiment of the present invention, in step 2), the amount of surface-modified Pt nanoparticle aqueous solution added is such that the mass ratio of surface-modified Pt nanoparticles to COFs photocatalyst is 0.1-2 wt%.
[0021] According to a preferred embodiment of the present invention, in step 2), the COFs photocatalyst is a COFs photocatalytic material linked by imine bonds, vinyl bonds, keto-enol bonds, hydrazone bonds, or triazine bonds.
[0022] According to a preferred embodiment of the present invention, in step 2), the pore size of the COFs photocatalyst is 0.5-4.9 nm.
[0023] According to a preferred embodiment of the present invention, in step 2), the adsorption time at room temperature is 1-24 hours.
[0024] According to a preferred embodiment of the present invention, in step 2), the product is cleaned with water.
[0025] A COFs photocatalyst with surface-modified Pt nanoparticles and pore-immobilized structure was prepared using the method described above.
[0026] The application of COFs photocatalyst immobilized with surface-modified Pt nanoparticle photocatalysts for light-driven water splitting to produce hydrogen.
[0027] According to a preferred embodiment of the present invention, the specific application method is as follows:
[0028] Under light irradiation, ascorbic acid was used as a sacrificial agent, and Pt nanoparticles on the surface of COFs photocatalyst were used as catalysts to produce hydrogen through water splitting. The concentration of ascorbic acid sacrificial agent was 0.1-5 mol / L, and the mass-volume ratio of catalyst to ascorbic acid was (5-15):(50-200), with units of mg / mL.
[0029] According to a preferred embodiment of the present invention, the concentration of the ascorbic acid sacrificial agent is 0.5-2 mol / L.
[0030] The COFs photocatalyst immobilized with surface-modified Pt nanoparticles obtained by this invention has good photocatalytic performance. The size of the surface-modified Pt nanoparticles in the photocatalyst is <3nm, and the loading of the surface-modified Pt nanoparticles is 0.1-2%wt of the COFs mass. This invention perfectly immobilizes the surface-modified Pt nanoparticles in the channels. The small molecules of the surface modification separate Pt from COFs, which reduces the Schottky barrier height while promoting electron transfer.
[0031] Technical features and advantages of the present invention:
[0032] 1. This invention utilizes the advantages of COFs' high crystallinity and highly tunable pore size and pore environment. By modifying the surface of Pt nanoparticles with small molecules and adjusting the size of Pt nanoparticles, and targeting the formation principle of the Schottky barrier, the invention successfully fixes the surface-modified Pt nanoparticles into the pores using the pore immobilization strategy of COFs. The surface-modified molecules separate Pt and COFs, reducing the height of the Schottky barrier while promoting electron transfer.
[0033] 2. Photocatalytic activity tests show that the COFs photocatalyst with immobilized Pt nanoparticles has a stable hydrogen generation rate and stable cyclic catalytic activity.
[0034] 3. The large specific surface area and regular and tunable pore structure are conducive to the immobilization of Pt nanoparticles and the efficient utilization of catalytic active sites and the mass transfer of reactants and products during the reaction process. The functional groups in its framework form strong hydrogen bonds with small molecules on the Pt surface, making Pt almost non-leaking, thus exhibiting excellent photocatalytic hydrogen evolution stability. Moreover, the special electronic conduction of small molecules enhances its photocatalytic activity. Attached Figure Description
[0035] Figure 1 Chemical structures of different COF photocatalysts and XRD patterns of sodium citrate-modified Pt nanoparticles immobilized by different COF photocatalysts.
[0036] Figure 2 Schematic diagram of COFs photocatalysts immobilized by Pt nanoparticles with sodium citrate surface modification;
[0037] Figure 3 TEM and particle size distribution images of surface-modified Pt nanoparticles prepared in Examples 1 and 3, from left to right: TEM image, particle size distribution image, and interplanar spacing at TEM image 111;
[0038] Figure 4 Examples 5 and 10 yielded photocatalysts and UPS of conventional photocatalysts;
[0039] Figure 5 Example 5: Steady-state fluorescence spectrum of the photocatalyst prepared;
[0040] Figure 6 Photocatalytic hydrogen evolution activity of catalysts with different loadings;
[0041] Figure 7 Photocatalytic hydrogen evolution performance of the photocatalysts prepared in Examples 5 and 10 at different reaction times;
[0042] Figure 8 Cyclic stability of the 0.5% PtNPs-TpPa-1 photocatalyst prepared in Example 5. Detailed implementation method:
[0043] Unless otherwise stated in the context of this application, the technical terms and abbreviations used herein have the conventional meanings known to those skilled in the art; unless otherwise stated, the raw material compounds used in the following examples are all commercially available.
[0044] The specific implementation methods for material preparation and characterization testing of various properties as described in this invention are as follows. Conversely, the following examples are only for further explanation and illustration of this invention and should not be considered as limiting the scope of the invention, which will be limited only by the claims.
[0045] Traditional photodeposition of Pt nanoparticles is the existing technology.
[0046] The COFs photocatalysts TpPa-1, CTF-1, and NKCOF-113 used in the examples were prepared according to the following methods:
[0047] Synthesis of TpPa-1: 2,4,6-Trihydroxybenzene-1,3,5-tricarboxaldehyde (Tp, 32 mg) and p-phenylenediamine (Pa, 24.3 mg) were added to a Shrek tube, followed by 1.5 mL of mesitylene, 1.5 mL of 1,4-dioxane, and 0.6 mL of an aqueous acetic acid solution (3 M). The tube was evacuated at 77 K to remove air, then sealed and transferred to an oil bath. Heating at 120 °C for 3 days yielded a red solid, which was separated by filtration and washed with tetrahydrofuran and methanol in a Soxhlet extractor for 24 hours. TpPa-1 was then activated by vacuum drying at 80 °C for 12 hours (90% yield). The XRD and chemical structure of TpPa-1 are shown below. Figure 1 .
[0048] Synthesis of CTF-1: 400 mg of terephthalonitrile (DCB) and 200 μL of CF3SO3H were added to an ampoule. The ampoule was evacuated, flame-sealed, and heated to 200 °C in a muffle furnace for 48 hours. The resulting solid was then washed with tetrahydrofuran in a Soxhlet extractor for 24 hours to completely remove unreacted monomers. The solid was dried under vacuum at 80 °C to obtain CTF-1. The chemical structure of CTF-1 is shown below. Figure 1 .
[0049] Synthesis of NKCOF-113: 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT, 12.6 mg, 0.032 mmol), 5,5'-bis(cyanomethyl)-2,2'-bipyridine (BCBPy, 11.3 mg, 0.048 mmol), and benzoic anhydride (22.5 mg, 0.1 mmol) were loaded into a 10 mL Pyrex tube. After degassing and sealing under vacuum, the tube was transferred to an oven and heated at 200 °C for 3 days to obtain a yellow solid. The solid was washed with tetrahydrofuran and methanol in a Soxhlet extractor for 48 hours (yield 95%). The solid was then dried under vacuum at 80 °C for 12 hours to obtain NKCOF-113. The chemical structure of NKCOF-113 is shown below. Figure 1 .
[0050] Example 1
[0051] Preparation of sodium citrate-modified Pt nanoparticles:
[0052] 0.1 mL of H₂PtCl₆ mother liquor (50 mM) and 9 mg of sodium citrate (0.035 mmol) were diluted to volume with 4.9 mL of water to obtain a mixed solution. The mixed solution was heated to 110 °C and kept at this temperature for 30 minutes with continuous stirring. The solution color changed from transparent to brown, indicating the end of the reaction. The PtNPs solution was cooled with ice water and stored at 5 °C to obtain a sodium citrate-modified Pt nanoparticle solution (1 mM). The TEM image, particle size distribution, and interplanar spacing of the sodium citrate-modified Pt nanoparticles are shown in [the image / description]. Figure 3 a.
[0053] Example 2:
[0054] Preparation of amino acid-modified Pt nanoparticles:
[0055] 0.1 mL of H2PtCl6 mother liquor (concentration 50 mM), 9 mg of sodium citrate (0.035 mmol), and 4 mg of cysteine, phenylalanine, or tryptophan were added to 4.9 mL of water to make up to a final volume, resulting in a mixed solution. The mixed solution was heated to 110 °C and kept at that temperature for 30 minutes. During the holding period, the reaction ended, yielding an amino acid-modified Pt nanoparticle solution (concentration 1 mM).
[0056] Example 3:
[0057] Preparation of PVP-modified Pt nanoparticles:
[0058] 0.1 mL of 50 mM H₂PtCl₆ aqueous solution was added to a Schlenk tube. Then, 50 mg of polyvinylpyrrolidone (PVP) and 4.9 mL of anhydrous ethylene glycol were added to the Schlenk tube. The mixture was sonicated for 5 minutes, then evacuated. The vacuum tube containing the mixed solution was heated in an oil bath at 120 °C until the solution turned brownish-yellow and then cooled to room temperature. The reacted solution was precipitated with acetone, and the product was collected by centrifugation for 5 minutes. The sample was then washed with acetone and hexane to remove excess free PVP. Finally, the product was dispersed in 5 mL of water to obtain a PVP-modified Pt nanoparticle solution (concentration 1 mM). TEM images, particle size distribution, and interplanar spacing of the PVP-modified Pt nanoparticles are shown below. Figure 3 b.
[0059] Example 4:
[0060] Preparation of 0.25% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0061] 10 mg of TpPa-1 and 0.025 mg of sodium citrate-modified Pt nanoparticles (prepared in Example 1) were mixed, ultrasonicated to ensure homogeneity, and stirred at room temperature for adsorption. After the reaction was complete, the product was washed for purification and dried to obtain 0.25% TpPa-1 COF-immobilized sodium citrate-modified Pt nanoparticles (denoted as 0.25% PtNPs-TpPa-1). A schematic diagram of the adsorption and immobilization of TpPa-1 and sodium citrate-modified Pt nanoparticles is shown below. Figure 2 .
[0062] The 0.25% PtNPs-TpPa-1 prepared in this embodiment can reduce the height of the Schottky barrier, such as... Figure 4 As shown.
[0063] Example 5:
[0064] Preparation of 0.5% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0065] 10 mg of TpPa-1 and 0.05 mg of sodium citrate-modified Pt nanoparticles (prepared in Example 1) were mixed, ultrasonicated to ensure homogeneity, and stirred at room temperature for adsorption. After the reaction was complete, the product was washed for purification and dried to obtain 0.5% TpPa-1COF-immobilized sodium citrate-modified Pt nanoparticles (denoted as 0.5% PtNPs-TpPa-1). XRD results are shown below. Figure 1 .
[0066] Example 6:
[0067] Preparation of 1% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0068] 10 mg of TpPa-1 and 0.1 mg of sodium citrate-modified Pt nanoparticle solution (prepared in Example 1) were mixed and ultrasonically treated to ensure uniform mixing. The mixture was then stirred and adsorbed at room temperature. After the reaction was completed, the product was washed and purified, and dried to obtain 1% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles (denoted as 1%PtNPs-TpPa-1).
[0069] Example 7:
[0070] Preparation of 2% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0071] 10 mg of TpPa-1 and 0.2 mg of sodium citrate-modified Pt nanoparticle solution (prepared in Example 1) were mixed and ultrasonically treated to ensure uniform mixing. The mixture was then stirred and adsorbed at room temperature. After the reaction was completed, the product was washed and purified, and dried to obtain 2% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles (denoted as 2%PtNPs-TpPa-1).
[0072] Example 8:
[0073] 0.5% CTF-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0074] 50 mg of CTF-1 and 0.25 mg of sodium citrate-modified Pt nanoparticles (prepared in Example 1) were mixed, ultrasonicated to ensure homogeneity, and stirred at room temperature for adsorption. After the reaction was complete, the product was washed for purification and dried to obtain 0.5% CTF-1COF-immobilized sodium citrate-modified Pt nanoparticles (denoted as 0.5% PtNPs-CTF-1). XRD results are shown below. Figure 1 .
[0075] Example 9:
[0076] 0.5% NKCOF-113 immobilized sodium citrate-modified Pt nanoparticles:
[0077] 50 mg of NKCOF-113 and 0.25 mg of sodium citrate-modified Pt nanoparticles (prepared in Example 1) were mixed, ultrasonicated to ensure homogeneity, and stirred at room temperature for adsorption. After the reaction was complete, the product was washed for purification and dried to obtain 0.5% NKCOF-113-immobilized sodium citrate-modified Pt nanoparticles (denoted as 0.5% PtNPs-NKCOF-113). XRD results are shown below. Figure 1 .
[0078] Example 10:
[0079] 0.5% TpPa-1COF immobilized PVP-modified Pt nanoparticles:
[0080] 10 mg TpPa-1 and 0.05 mg of PVP-modified Pt nanoparticle solution (prepared in Example 3) were mixed and ultrasonically treated to ensure uniform mixing. The mixture was then stirred and adsorbed at room temperature. After the reaction was completed, the product was washed and purified, and dried to obtain 0.5% TpPa-1COF immobilized PVP-modified Pt nanoparticles (denoted as 0.5%PtNPs(PVP)-TpPa-1).
[0081] The 0.5% PtNPs(PVP)-TpPa-1 prepared in this embodiment can reduce the height of the Schottky barrier, such as... Figure 4 As shown.
[0082] Comparative Example 1
[0083] Preparation of 3% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0084] 10 mg of TpPa-1 and 0.3 mg of sodium citrate-modified Pt nanoparticle solution (prepared in Example 1) were mixed and ultrasonically treated to ensure uniform mixing. The mixture was then stirred and adsorbed at room temperature. After the reaction was completed, the product was washed and purified, and dried to obtain 3% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles (denoted as 3%PtNPs-TpPa-1).
[0085] Comparative Example 2
[0086] Preparation of 4% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles:
[0087] 10 mg of TpPa-1 and 0.4 mg of sodium citrate-modified Pt nanoparticle solution (prepared in Example 1) were mixed and ultrasonically treated to ensure uniform mixing. The mixture was then stirred and adsorbed at room temperature. After the reaction was completed, the product was washed and purified, and dried to obtain 4% TpPa-1COF immobilized sodium citrate-modified Pt nanoparticles (denoted as 4%PtNPs-TpPa-1).
[0088] Comparative Example 3
[0089] COFs photocatalyst photodeposited Pt nanoparticles, prepared by existing methods (denoted as 0.5%Pt-TpPa-1).
[0090] Experimental Example 1
[0091] Photocatalytic hydrogen evolution with different catalysts:
[0092] 10 mg of the catalyst powders prepared in Examples 4-7 and Comparative Examples 1-2 were weighed into 200 mL of a photoreactor, and 100 mL of 1 M ascorbic acid aqueous solution was added. The photoreactor containing the mixed solution was installed in a closed system. After complete degassing, the photoreactor was directly irradiated with a 300 W xenon lamp (λ>420 nm), and the temperature of the photoreactor was maintained at 5 °C. The reaction gas was extracted every 0.5 h, and gas chromatography analysis was performed using argon as the carrier gas through a molecular sieve column. The photocatalytic hydrogen evolution activity of different catalysts is shown in the figure. Figure 6 ,pass Figure 6It can be seen that the optimal loading of Pt is 0.5%wt, and its hydrogen evolution activity is twice that of the traditional photodeposition of Pt nanoparticles (0.5%Pt-TpPa-1).
[0093] Experimental Example 2
[0094] 1. The steady-state fluorescence spectrum of 0.5% PtNPs-TpPa-1 obtained in Example 5 is as follows: Figure 5 As shown, through Figure 5 It can be seen that the fluorescence spectrum of 0.5% PtNPs-TpPa-1 is smaller than that of conventional photodeposited Pt nanoparticles (0.5% Pt-TpPa-1). Therefore, the 0.5% PtNPs-TpPa-1 of the present invention can promote electron transfer.
[0095] 2. The photocatalytic hydrogen evolution performance of the photocatalysts prepared in Examples 5 and 10 was tested and compared with that of conventional photodeposited Pt nanoparticles (0.5% Pt-TpPa-1). The photocatalytic hydrogen evolution performance is shown in the figure. Figure 7 .
[0096] 3. Following the method in Example 1, photocatalytic hydrogen evolution was performed. After four cycles of testing, the 0.5% PtNPs-TpPa-1 photocatalyst prepared in Example 5 showed no significant change in activity, indicating that it has good stability. (See [link]). Figure 8 .
Claims
1. A method for reducing the Schottky barrier at the interface between COFs photocatalyst and Pt co-catalyst, comprising the following steps: 1) Preparation of surface-modified Pt nanoparticles The chloroplatinic acid mother liquor, surface modifier, and reducing agent were mixed and brought to a final volume to obtain a mixed solution. This mixed solution underwent a solvothermal reaction. After the reaction, an aqueous solution of surface-modified Pt nanoparticles was obtained. The concentration of the chloroplatinic acid mother liquor was 40-60 mM. The surface modifier was either amino acid or sodium citrate. The reducing agent was either sodium citrate or ethylene glycol. The concentration of chloroplatinic acid in the mixed solution was 0.5-3 mM. When sodium citrate was used as the reducing agent, water was used to bring the solution to a final volume as the solvent. The concentration of the reducing agent in the mixed solution was 0.034-0.07 mmol / mL, and the concentration of the surface modifier was 0-2 mg / mL. When ethylene glycol was used as the reducing agent, ethylene glycol was used to bring the solution to a final volume, acting as both a reducing agent and a solvent. The concentration of the surface modifier in the mixed solution was 4-30 mg / mL. 2) Add COFs photocatalyst to the aqueous solution of surface-modified Pt nanoparticles. The amount of surface-modified Pt nanoparticles added is such that the mass ratio of surface-modified Pt nanoparticles to COFs photocatalyst is 0.1-2wt%. Sonicate to mix evenly, stir at room temperature for adsorption and fixation. After the reaction is completed, wash the product for purification to reduce the Schottky barrier height. Dry the purified product.
2. The method according to claim 1, characterized in that, In step 1), the solvothermal reaction temperature is 90-120℃ and the reaction time is 10-120 min.
3. The method according to claim 1, characterized in that, In step 2), the COFs photocatalyst is a COFs photocatalytic material linked by imine bonds, vinyl bonds, keto-enol bonds, hydrazone bonds, or triazine bonds. The pore size of the COFs photocatalyst is 0.5-4.9 nm, the adsorption time at room temperature is 1-24 h, and the product is cleaned with water.
4. A COFs photocatalyst with immobilized pores and surface-modified Pt nanoparticles, prepared by any one of the methods described in claims 1-3.
5. The application of the COFs photocatalyst immobilized with surface-modified Pt nanoparticles as described in claim 4, for photo-driven water splitting to produce hydrogen.
6. The application according to claim 5, characterized in that, The specific application methods are as follows: Under illumination, ascorbic acid was used as a sacrificial agent, and Pt nanoparticles on the surface of COFs photocatalyst were used as catalysts to produce hydrogen through water splitting. The concentration of ascorbic acid sacrificial agent was 0.1-5 mol / L, and the mass-volume ratio of catalyst to ascorbic acid was (5-15):(50-200), with units of mg / mL.