A hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst and its preparation method and application

Abstract

The present invention discloses a hydrogen-bond-enhanced graphene bis(yne) / TiO2 heterojunction photocatalyst, its preparation method, and application. The preparation method is as follows: S1: dissolving penta[(trimethylsilyl)ethynyl]pyridine monomer in an organic solvent, adding CuCl as a catalyst to react; S2: separating the solid product by centrifugation after the reaction; S3: washing with an organic solvent to remove unreacted monomer, then washing with dilute hydrochloric acid, and drying to obtain a pyridine N-doped graphene bis(yne) material; S4: subjecting the TiO2 to a hydrothermal treatment; S5: ultrasonically mixing the pyridine N-doped graphene bis(yne) material and the hydrothermally treated TiO2, and continuously stirring to obtain a graphene bis(yne) hydrogen-bond heterojunction photocatalyst. The present invention constructs a graphene bis(yne) / TiO2 heterojunction through a hydrogen-bond assembly strategy, ensuring the integrity of the conjugated structure while strengthening the heterojunction interface, reducing the interfacial charge transfer barrier, and achieving efficient charge separation and transfer. The catalyst exhibits excellent photocatalytic hydrogen production activity in applications involving photocatalytic water splitting to produce hydrogen.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic materials, and specifically relates to a graphene diyne / TiO2 heterojunction photocatalyst constructed through a hydrogen bond assembly strategy, a preparation method thereof, and an application thereof in photocatalytic water decomposition to produce hydrogen. Background Art

[0002] The use of clean, pollution-free and renewable energy such as solar energy to convert small molecules such as water and carbon dioxide, which are abundant in nature, into chemical fuels and high-value-added chemicals is of great significance to the sustainable development of green chemistry and energy. Photocatalytic technology, with its mild reaction conditions and environmentally friendly characteristics, has become one of the most promising key technologies in the field of small molecule conversion, and the design and preparation of efficient photocatalysts are the core of the breakthrough of this technology. Inorganic semiconductor materials represented by TiO2 have the advantages of suitable energy level structure, high stability, low cost and easy preparation. They are widely used in the field of photocatalytic water decomposition to produce hydrogen and carbon dioxide reduction. However, single semiconductor photocatalysts have the problem of rapid recombination of photogenerated electron-hole pairs, which seriously limits the photocatalytic efficiency. Heterojunction can promote the effective migration and separation of photogenerated carriers by utilizing the energy level difference effect, and is an important strategy for constructing highly active photocatalysts. Graphene diyne (GDY) is a kind of sp and sp 2 A novel carbon material composed of hybridized carbon atoms exhibits direct band gaps, suitable energy levels, and excellent carrier mobility. The large surface area and porous structure of graphene diacetylene provide abundant adsorption sites for reactants and effectively promote mass transport in both in-plane and out-of-plane directions. Furthermore, graphene diacetylene can be prepared through monomer polymerization, resulting in highly tunable structure and functionality. These unique properties make it an ideal material for constructing heterojunctions.

[0003] Currently, two main strategies for constructing GDY-inorganic semiconductor heterostructures are in-situ growth and physical mixing. The in-situ growth strategy employs the following technical features: The GDY-inorganic semiconductor heterojunction is constructed by adsorbing a semiconductor precursor metal onto the GDY surface, followed by hydrothermal or calcination. The process typically requires hydrothermal or high-temperature calcination.

[0004] The above strategy has the following defects: (1) Destruction of conjugated structure: The high temperature process will partially destroy the acetylene bond (C≡C) and benzene ring conjugated skeleton of GDY, reducing its carrier mobility; (2) Process complexity: It requires multiple chemical reactions, and the reaction conditions are harsh, which is not atom-economical and difficult to prepare on a large scale.

[0005] Another common technique is the physical mixing method, which features the following: GDY and inorganic semiconductor powders are directly mixed by stirring or ultrasonic dispersion to form a heterojunction. This method is simple to operate, does not require harsh reaction conditions, and is suitable for large-scale production. However, GDY / inorganic semiconductor heterojunctions prepared by physical methods usually rely on van der Waals forces to connect, resulting in weak interfacial forces and high charge transfer barriers, leading to low efficiency in the separation and transfer of photogenerated carriers.

[0006] In summary, existing technologies are unable to achieve strong interfacial coupling while maintaining the integrity of the GDY conjugated structure, severely restricting the charge transfer performance at the GDY-inorganic semiconductor heterojunction interface. Therefore, it is urgent to develop a new interface engineering strategy that can regulate the interaction between GDY and inorganic semiconductors at the atomic scale, balancing efficient charge transfer with structural stability. Summary of the Invention

[0007] In response to the above-mentioned problems, the present invention provides a hydrogen-bond-enhanced graphene bis(yne) / TiO2 heterojunction photocatalyst, its preparation method and application, aiming to construct a graphene bis(yne) / TiO2 heterojunction through a hydrogen-bond assembly strategy, thereby strengthening the heterojunction interface effect while ensuring the integrity of the graphene bis(yne) conjugated structure, effectively reducing the interfacial charge transfer barrier, and realizing efficient charge separation and transfer.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] In one aspect, the present invention provides a method for preparing a hydrogen bond-enhanced graphene diyne / TiO2 heterojunction photocatalyst, comprising the following steps:

[0010] S1: Dissolve penta[(trimethylsilyl)ethynyl]pyridine monomer in an appropriate amount of organic solvent, add CuCl as a catalyst, mix evenly with ultrasonic wave, and then fully react at a certain temperature to ensure that the monomer is fully polymerized to form pyridine N-doped graphene diyne (NGDY); (Schematic diagram of N-doped graphene diyne synthesis is shown in Figure 1) Figure 2 The specific reaction mechanism is as follows: Penta[(trimethylsilyl)ethynyl]pyridine first reacts with CuCl to form a monovalent copper species intermediate, which then undergoes a reductive elimination reaction during the formation of the butyne bridge to generate zero-valent copper, and the alkynyl group undergoes coupling. The generated zero-valent copper will be further oxidized to monovalent copper (and some divalent copper) in the presence of air to enter the next catalytic cycle (refer to Figure 3 Mechanism diagram).

[0011] S2: After the reaction is completed, the solid product is separated by centrifugation;

[0012] S3: The solid product is further washed with an organic solvent to remove unreacted monomers, then washed with dilute hydrochloric acid to remove copper oxide species, and then dried to obtain pyridine N-doped graphene diyne (NGDY). The resulting pyridine N-doped graphene diyne (NGDY) is in powder form and is black or grayish-black in color. XRD, TEM, Raman spectroscopy, and other methods confirm the successful synthesis of the material.

[0013] S4: hydrothermally treating TiO2 to increase the content of surface hydroxyl groups;

[0014] S5: ultrasonically mixing the pyridine N-doped graphene diyne material (NGDY) and hydrothermally treated TiO2 (TrTiO2), and continuously stirring to obtain the hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst.

[0015] Preferably, in step S1, the molar ratio of the added amounts of penta[(trimethylsilyl)ethynyl]pyridine monomer and CuCl is 1:1, wherein CuCl is used as a catalyst.

[0016] Preferably, the organic solvent in step S1 is DMF; the organic solvent in step S3 is one or more of DMF, THF, and methanol, and the concentration of dilute hydrochloric acid in step S3 is 0.1 M.

[0017] Preferably, in step S1, the reaction process is: heating the reaction at 50-60° C. for 20-24 hours.

[0018] Preferably, in step S4, the specific process of hydrothermal treatment is: adding TiO2 powder to an appropriate amount of distilled water, stirring continuously for a period of time, then transferring the mixture to a polytetrafluoroethylene-lined steel autoclave, heating at 120-150°C for 10-12 hours, and then cooling naturally; centrifuging the precipitate, washing it with distilled water several times, and then drying the product at 80-100°C to obtain the hydrothermally treated TiO2 powder.

[0019] Preferably, in step S4, the TiO2 is P25 nano-titanium dioxide.

[0020] Preferably, in step S5, the mass ratio of pyridine N-doped graphene diyne to hydrothermally treated TiO2 is 1-7%, preferably 5%.

[0021] In a second aspect, the present invention proposes a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst prepared by the above preparation method.

[0022] In a third aspect, the present invention proposes the application of the above-mentioned hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst in photocatalytic water decomposition to produce hydrogen. The NGDY / TiO2 heterojunction photocatalyst of the present invention exhibits better photocatalytic hydrogen production activity.

[0023] The present invention synthesizes pyridine nitrogen-doped graphene diacetylene by designing nitrogen-doped graphene diacetylene monomers; since nitrogen atoms and -OH can form hydrogen bonds, NGDY and hydrothermally treated TiO2 form NGDY / TiO2 heterojunctions through self-assembly (refer to Figure 1 ); The heterojunction is prepared by physical mixing, avoiding hydrothermal and high-temperature sintering, and will not destroy the intrinsic structure of graphene diacetylene. The process is simple and efficient. Due to the presence of hydrogen bonding at the heterojunction interface, the interaction between the heterojunction components is enhanced, the interfacial charge transfer barrier is significantly reduced, and the interfacial charge separation and transfer are effectively promoted. The present invention synergistically enhances the photocatalytic activity and stability of pyridine nitrogen-doped graphene diacetylene NGDY / TiO2 heterojunction catalysts through nitrogen doping and hydrogen bonding.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] 1. Strong interface coupling and efficient charge transfer

[0026] By replacing traditional van der Waals forces with hydrogen bonds, an internal electric field is formed at the heterojunction interface, providing a fast charge transfer channel (hundreds of femtoseconds), thereby significantly reducing the interface potential barrier and promoting efficient separation and transfer of interface charges.

[0027] 2. Structural integrity and stability assurance

[0028] By utilizing a hydrogen bonding assembly strategy, high-temperature calcination or harsh chemical treatments are avoided, maintaining high carrier mobility. Strong interfacial coupling enhances the mechanical strength and photocorrosion resistance of the heterojunction, extending the life of the photocatalyst.

[0029] 3. Controllable preparation and scalability potential

[0030] One-step synthesis: Directly construct heterojunctions under mild conditions (such as room temperature stirring, without high temperature or high pressure), simplifying the process and reducing energy consumption.

[0031] 4. Significant increase in photocatalytic hydrogen production activity

[0032] Under the same conditions (e.g., UV-visible light irradiation), the photocatalytic hydrogen production efficiency is 2 times higher than that of GDY / TiO2. Stability: After 5 consecutive cycles (30 hours), the activity retention rate is >90%.

[0033] In summary, the technical solution of the present invention solves the core contradiction between weak interface coupling and structural destruction in traditional heterojunctions through atomic-level interface engineering, realizes the coordinated optimization of photocatalysts in three dimensions: photogenerated charge separation and transport dynamics, structural stability, and reaction engineering, and provides a breakthrough material design strategy for efficient solar energy conversion and utilization.

[0034] The present invention constructs a graphene diacetylene / TiO2 heterojunction through a hydrogen-bonding assembly strategy. While maintaining the integrity of the graphene diacetylene conjugated structure, it also strengthens the heterojunction interface, effectively reducing the interfacial charge transfer barrier and achieving efficient charge separation and transfer. The catalyst exhibits excellent photocatalytic hydrogen production activity in applications involving photocatalytic water splitting to produce hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst mechanism of the present invention;

[0036] Figure 2 Schematic diagram of the synthesis of nitrogen-doped graphene diyne NGDY;

[0037] Figure 3 This is the synthesis mechanism diagram of N-doped graphene diyne;

[0038] Figure 4 Comparison of high-resolution O 1s XPS of TiO2 before and after hydrothermal treatment;

[0039] Figure 5 High-resolution TEM comparison images of nitrogen-doped graphene diyne and graphene diyne prepared in Example 1;

[0040] Figure 6 This is the Raman spectrum of N-doped graphene diyne (NGDY) prepared in Example 1;

[0041] Figure 7 This is a high-resolution TEM comparison image of the GDY / TiO2 heterojunction catalyst prepared in Comparative Example 1 and the NGDY / TiO2 prepared in Example 1;

[0042] Figure 8 XRD comparison diagram of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 prepared in Example 1;

[0043] Figure 9 The infrared spectra of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 products prepared in Example 1 are shown;

[0044] Figure 10The Raman spectra comparison diagram of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 product prepared in Example 1 and its magnified diagram;

[0045] Figure 11 Figure 2 is the fluorescence spectra of related products, where (a) is the fluorescence spectra of TiO2, GDY / TiO2 and NGDY / TiO2; (b) is the time-resolved fluorescence spectra of TiO2, GDY / TiO2 and NGDY / TiO2;

[0046] Figure 12 The photocatalytic hydrogen production activity of GDY / TiO2 and NGDY / TiO2 with different doping amounts;

[0047] Figure 13 This is a test chart of the stability of 5% NGDY / TiO2 photocatalytic hydrogen production. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0049] Example 1 (NGDY / TiO2 heterojunction catalyst)

[0050] A method for preparing a hydrogen bond-enhanced graphene diyne / TiO2 heterojunction photocatalyst comprises the following steps:

[0051] (1) Penta[(trimethylsilyl)ethynyl]pyridine and CuCl were mixed in a molar ratio of 1:1, dissolved in an appropriate amount of DMF solution, and ultrasonically mixed until uniform; heated at 60°C for 24 hours to ensure that the monomers were fully polymerized to form pyridine N-doped graphene diyne (NGDY);

[0052] (2) After the reaction is completed, the solid product is separated by centrifugation; unreacted monomers are removed by washing with DMF and THF, and copper oxide species are removed by washing with dilute hydrochloric acid;

[0053] (3) After drying, pyridine N-doped graphene diyne material is obtained;

[0054] (4) Commercial TiO2 (P25) material was hydrothermally treated to increase the surface hydroxyl content. The hydrothermal treatment process was as follows: 2 g of TiO2 powder was added to 50 mL of distilled water and stirred continuously for 1 h. The mixture was then transferred to a 100 mL polytetrafluoroethylene-lined steel autoclave and heated at 150°C for 10 h, followed by natural cooling. The precipitate was separated by centrifugation and washed five times with distilled water. The product was dried at 80°C to obtain the hydrothermally treated TiO2 powder. Figure 4 TiO2 before hydrothermal treatment ( Figure 4 (a)) and TiO2 after hydrothermal treatment ( Figure 4 (b) High-resolution O 1s XPS comparison diagram shows that the hydroxyl group on the TiO2 surface can be increased by the hydrothermal method.

[0055] (5) Pyridine nitrogen-doped graphene diyne (NGDY) and hydrothermally treated TiO2 are ultrasonically mixed and stirred for 12 hours to obtain the hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst (NGDY / TiO2).

[0056] Example 2 (NGDY / TiO2 heterojunction catalyst)

[0057] A method for preparing a hydrogen bond-enhanced graphene diyne / TiO2 heterojunction photocatalyst comprises the following steps:

[0058] (1) Penta[(trimethylsilyl)ethynyl]pyridine and CuCl were mixed in a molar ratio of 1:1, dissolved in an appropriate amount of DMF solution, and ultrasonically mixed until uniform; heated at 65°C for 20 hours to ensure that the monomers were fully polymerized to form pyridine N-doped graphene diyne (NGDY);

[0059] (2) After the reaction is completed, the solid product is separated by centrifugation; unreacted monomers are removed by washing with THF and methanol, and copper oxide species are removed by washing with dilute hydrochloric acid;

[0060] (3) After drying, pyridine N-doped graphene diyne material is obtained;

[0061] (4) Commercial TiO2 (P25) material was hydrothermally treated to increase the surface hydroxyl content. The hydrothermal treatment process was as follows: 2 g of TiO2 powder was added to 50 mL of distilled water and stirred continuously for 1.5 h. The mixture was then transferred to a 100 mL polytetrafluoroethylene-lined steel autoclave, heated at 120 °C for 12 h, and then cooled naturally. The precipitate was separated by centrifugation and washed five times with distilled water. The product was dried at 100 °C to obtain hydrothermally treated TiO2 (TrTiO2) powder.

[0062] (5) Pyridine nitrogen-doped graphene diyne (NGDY) and hydrothermally treated TiO2 are ultrasonically mixed and stirred for 12 hours to obtain the hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst (NGDY / TiO2).

[0063] Comparative Example 1 (GDY / TiO2 heterojunction catalyst)

[0064] Preparation of the GDY / TiO2 heterojunction catalyst: The GDY / TiO2 heterojunction catalyst was prepared by ultrasonically mixing graphite diyne (GDY) with hydrothermally treated commercial TiO2 (P25) material and stirring for 12 hours. The hydrothermal treatment of the TiO2 was the same as in Example 1.

[0065] Figure 5 Comparison of high-resolution TEM images of nitrogen-doped graphene diyne (GDD) and graphene diyne (GDD) prepared in Example 1. The curved stripes represent the spacing between carbon layers, determined to be 0.373 nm for NGDY. High-resolution TEM images of GDD reveal an interlayer spacing of 0.364 nm, demonstrating that nitrogen doping increases interlayer spacing.

[0066] Figure 6 This is the Raman spectrum of N-doped graphene diacetylene prepared in Example 1; the Raman spectrum shows two prominent peaks, belonging to the G and D bands, corresponding to the E2g stretching vibration mode and the sp 2 The breathing vibration of the carbon domain. The peak of the conjugated diyne bond (–C≡C–C≡C–) vibration is at 2183 cm −1 Observed.

[0067] Figure 7 This is a high-resolution TEM comparison of the GDY / TiO2 heterojunction catalyst prepared in Comparative Example 1 and the NGDY / TiO2 prepared in Example 1. Compared with the interface between TiO2 and GDY, the interface contact between TiO2 and NGDY is more extensive.

[0068] Figure 8 XRD comparison diagrams of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 prepared in Example 1; all samples exhibit diffraction peaks similar to those of TiO2, with the peaks at 25.3 and 27.4 being characteristic lines of anatase (101) and rutile (110), respectively. Due to the low contents of GDY and NGDY, no obvious diffraction patterns were observed.

[0069] Figure 9The infrared spectra of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 products prepared in Example 1 are shown. Compared with TiO2 and TiO2-GDY, the FTIR spectrum of TiO2-NGDY shows a broadened hydrogen bond-OH stretching absorption, indicating that a hydrogen bond is formed between TiO2 and N-doped GDY.

[0070] Figure 10 The Raman spectra of TiO2, GDY-TiO2 prepared in Comparative Example 1, and NGDY-TiO2 prepared in Example 1 are compared and magnified. TEM and other characterizations confirm that the NGDY / TiO2 heterojunction catalyst has more extensive interfacial contact with TiO2. The Raman spectra show clear peak positions, with the characteristic peaks of anatase TiO2 located at 143, 397, 518, and 640 cm -1 Compared with pure GDY and NGDY, the peak position of the G band in the TiO2 / GDY and TrTiO2 / NGDY heterojunctions shifts. The magnitude of the G band peak shift in the TiO2 / NGDY heterojunction is greater than that in the TiO2 / GDY heterojunction, indicating a stronger interaction between NGDY and TiO2.

[0071] Figure 11 The fluorescence spectra of the related products are shown in Figure 2, where (a) is the fluorescence spectra of TiO2, GDY / TiO2 and NGDY / TiO2; (b) is the time-resolved fluorescence spectra of TiO2, GDY / TiO2 and NGDY / TiO2. Compared with TiO2, the steady-state photoluminescence (PL) spectrum of the heterojunction shows obvious PL quenching ( Figure 11 (a) in the figure). The quenching of TiO2-NGDY is stronger than that of TiO2-GDY, indicating that the presence of H bonds can enhance the promotion effect. The average luminescence decay lifetime (τ avg = 0.790ns), which implies favorable interfacial charge transfer and separation, consistent with the steady-state fluorescence spectroscopy results.

[0072] Application Examples

[0073] The photocatalytic hydrogen production activity of different heterojunction catalysts was verified respectively. The following comparative test was designed. Taking the preparation process of Example 1 and the comparative example as an example, the mass ratio of NGDY or GDY to hydrothermal TiO2 was designed to be 1%, 2%, 5%, and 7%, respectively. The hydrogen production efficiency was compared by combining GDY, NGDY and hydrothermal TiO2 alone. The specific experimental process is as follows:

[0074] For each experiment, 5 mg of catalyst sample was dispersed in 5 mL of an aqueous solution containing 25% TEOA by volume. The reaction cell was degassed with argon for 20 minutes to remove dissolved oxygen. The photocatalytic reaction was illuminated by an Oriel 300 W xenon arc lamp, with a light flux reaching the sample of approximately 250 mW / cm. -2 The gaseous products were analyzed by gas chromatography (N2 and Ar as carrier gases). During the irradiation process, the reaction system was stirred by a magnetic stirrer and the temperature was controlled by circulating cooling water (25°C). Each reaction lasted for 6 h. The comparison results are shown in Figure 2. Figure 12 As shown in the figure, when the mass ratio of NGDY to titanium dioxide is 5%, the catalytic hydrogen production activity is the highest, and the catalytic activity of the NGDY / TiO2 heterojunction is twice that of the GDY / TiO2 heterojunction.

[0075] Conclusion: Compared with GDY / TiO2, NGDY / TiO2 heterojunction exhibits better photocatalytic hydrogen production activity, and the photocatalytic hydrogen production is increased by 2 times, demonstrating its great potential for photocatalytic hydrogen production.

[0076] On the basis of the above comparison of catalytic hydrogen production activity, 5% NGDY / TiO2 photocatalyst was taken as a sample to evaluate the stability of the prepared heterojunction photocatalyst. Five consecutive photocatalytic tests were carried out, each for 6 hours. After each test, the sample was collected by centrifugation and washed several times with water and ethanol, and then dried overnight for the next test.

[0077] The stability test results are as follows Figure 13 As shown, it can be seen that the NGDY / TiO2 photocatalyst has good stability: the activity retention rate is >90% after 30 hours of continuous cycle testing.

[0078] In summary, the core innovation of this invention lies in constructing a pyridine nitrogen-doped graphene diacetylene (NGDY) / TiO2 heterojunction through a hydrogen-bonding assembly strategy. While maintaining the integrity of the conjugated structure of the graphene diacetylene, the hydrogen bonding between nitrogen atoms and the hydroxyl groups (-OH) on the TiO2 surface is utilized to strengthen the interfacial coupling, significantly improving the photocatalytic performance. The key technical points are as follows:

[0079] 1. Hydrogen bond bridged heterojunction structure (core structural characteristics)

[0080] NO···H hydrogen bond interface: The N atoms in pyridine nitrogen-doped graphene diyne (NGDY) form hydrogen bonds (NO···H) with the -OH on the surface of hydroxylated TiO2, constructing a strongly interacting heterojunction interface, replacing the traditional van der Waals force connection.

[0081] Nitrogen doping site design: Through the polymerization of penta[(trimethylsilyl)ethynyl]pyridine monomers, pyridine nitrogen atoms were precisely introduced into the GDY backbone as hydrogen bond donor sites.

[0082] Hydroxylation of TiO2 surface: Increase the surface hydroxyl density of TiO2 (such as P25) through hydrothermal treatment and optimize the conditions for hydrogen bond formation.

[0083] 2. Low-temperature hydrogen bond assembly process (core method features)

[0084] Synthesis of NGDY: Penta[(trimethylsilyl)ethynyl]pyridine and CuCl are used as raw materials, and low-temperature polymerization reaction is carried out in DMF. NGDY is obtained by centrifugation, washing, and drying.

[0085] TiO2 hydroxylation treatment: Hydrothermal method (such as 150°C, 6 hours) to activate the surface hydroxyl groups of TiO2.

[0086] Hydrogen Bond Self-Assembly: NGDY and hydroxylated TiO2 are ultrasonically mixed and stirred at room temperature for 12 hours to directly form a heterojunction, eliminating the need for high temperatures or pressures. This low-temperature hydrogen bond self-assembly process avoids damaging the GDY conjugated structure, resulting in simple operation and high economic efficiency.

[0087] 3. Photocatalytic performance optimization (core functional characteristics)

[0088] Interface charge transfer: The hydrogen bond interface provides a low-barrier channel, and the carrier migration rate is increased by more than 2 times.

[0089] Stability design: Hydrogen bonds are beneficial to enhancing interfacial interactions and improving structural stability during reactions.

[0090] In summary, the technical solution of the present invention solves the core contradiction between weak interface coupling and structural destruction in traditional heterojunctions through atomic-level interface engineering, realizes the coordinated optimization of photocatalysts in three dimensions: charge dynamics, structural stability, and reaction engineering, and provides a breakthrough material design strategy for efficient solar energy conversion and utilization.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst, characterized in that: The process steps include: S1: dissolving penta[(trimethylsilyl)ethynyl]pyridine monomer in an appropriate amount of organic solvent, adding an appropriate amount of CuCl as a catalyst, and carrying out a full reaction at a certain temperature to ensure that the monomer is fully polymerized to form pyridine N-doped graphene diyne; S2: After the reaction is completed, the solid product is separated by centrifugation; S3: The solid product is further washed with an organic solvent to remove unreacted monomers, then washed with dilute hydrochloric acid, and then dried to obtain a pyridine N-doped graphene diacetylene material; S4: hydrothermally treating TiO2 to increase the content of surface hydroxyl groups; S5: Ultrasonic mixing of the pyridine N-doped graphene diacetylene material and the hydrothermally treated TiO2 is performed, and continuous stirring is performed to obtain the hydrogen bond enhanced graphene diacetylene / TiO2 heterojunction photocatalyst.

2. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: In step S1, the molar ratio of the added amount of penta[(trimethylsilyl)ethynyl]pyridine monomer and CuCl is 1:

1.

3. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: The organic solvent in step S1 is DMF; the organic solvent in step S3 is one or more of DMF, THF, and methanol, and the concentration of dilute hydrochloric acid is 0.1 M.

4. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: In step S1, the reaction process is: heating the reaction at 50-60° C. for 20-24 hours.

5. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: In step S4, the specific process of the hydrothermal treatment is as follows: adding TiO2 powder to an appropriate amount of distilled water, stirring continuously for a period of time, then transferring the mixture to a polytetrafluoroethylene-lined steel autoclave, heating at 120-150°C for 10-12 hours, and then cooling naturally; The precipitate is separated by centrifugation and washed several times with distilled water. The obtained product is dried at 80-100° C. to obtain hydrothermally treated TiO2 powder.

6. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: In the step S4, the TiO2 is P25 nano-titanium dioxide.

7. The method for preparing a hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst according to claim 1, characterized in that: In step S5, the mass ratio of pyridine N-doped graphene diacetylene to hydrothermally treated TiO2 is 1-7%.

8. A hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst, characterized in that: The method is as described in any one of claims 1 to 7.

9. Use of the hydrogen bond enhanced graphene diyne / TiO2 heterojunction photocatalyst as claimed in claim 8 in photocatalytic water decomposition to produce hydrogen.

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