Conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalysts, their preparation methods and applications

Abstract

This application relates to the field of nanophotocatalytic materials technology, and discloses a conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst, its preparation method, and its application. The preparation method includes: dissolving Pluronic F127 in tetrahydrofuran to obtain a homogeneous solution; adding glacial acetic acid and hydrochloric acid to the solution and stirring until homogeneous to obtain a precursor solution; rapidly adding tetrabutyl titanate to the precursor solution and stirring until homogeneous; then removing the solvent and crystallizing in situ; collecting the solid phase and calcining it to obtain mesoporous titanium dioxide; dispersing the conjugated polyelectrolyte (CPEs) in a solvent, then adding the mesoporous titanium dioxide for self-assembly, removing the solvent, and obtaining the composite photocatalyst. The composite photocatalyst prepared in this application exhibits a wider visible light response range and superior photocatalytic water splitting for hydrogen production. It can fully utilize the photosensitization and charge transport advantages of CPEs under extremely low loading conditions, achieving excellent photocatalytic hydrogen production performance without the need for noble metal co-catalysts.

Description

Technical Field

[0001] This application relates to the field of nanophotocatalytic materials technology, and in particular to conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalysts, their preparation methods, and applications. Background Technology

[0002] Solar energy is a very important renewable resource that can be easily converted into other energy sources, effectively alleviating the increasingly serious environmental problems and resource crises. Photocatalysis technology can not only convert abundant and clean solar energy into other green energy sources (such as hydrogen and hydrocarbons), but also reduce carbon dioxide and degrade various pollutants, showing broad application prospects.

[0003] Titanium dioxide (TiO2), as a cheap, non-toxic, and stable photocatalyst, has been widely used in various photocatalytic reactions, such as photocatalytic water splitting, degradation of organic pollutants, and photocatalytic reduction of carbon dioxide, exhibiting good catalytic effects. However, its relatively wide band gap (3.2 eV) means it can only be excited by ultraviolet light (accounting for only 5% of incident sunlight), making it difficult to utilize visible light (52%) and infrared light (43%), which constitute a larger proportion of the solar spectrum. Furthermore, TiO2 has a high recombination rate of photogenerated electron-hole pairs. These factors, to some extent, limit its further development in the field of photocatalysis.

[0004] To address the inherent defects of TiO2, researchers have proposed various modification strategies to enhance its photocatalytic performance. These include morphology and structure control, defect engineering, crystal plane engineering, elemental doping, and heterostructure construction to adjust its bandgap structure and broaden its photoresponse range. For instance, patent CN111268725A describes a solvothermal method for preparing porous titanium dioxide nanosheets with exposed {001} crystal planes as a photocatalyst. This provides a higher specific surface area and more active sites, thus improving the photocatalytic performance of TiO2. However, its hydrogen production rate without a supported noble metal co-catalyst is only about 45 μmol g⁻¹. -1 h -1 The optimal catalytic effect of 2239 μmol g was achieved by loading 4 wt% Pt. -1 h -1 Its catalytic performance mainly relies on loading the noble metal Pt to provide active sites, which greatly increases the cost of its application in photocatalytic water splitting; for example, patent CN115254097A reports a mesoporous TiO2 (meso-TiO2) nanosheet photocatalyst constructed by hydrogen reduction treatment, and combined with a liquid nitrogen freezing-assisted photoreduction strategy to cluster Pt on the surface of the mesoporous nanosheets, exhibiting a high photocatalytic hydrogen production efficiency (6.15 mmol·g). -1 ·h-1 While this strategy improves Pt utilization efficiency and enhances the photocatalytic performance of the material to some extent, it is not only cumbersome in its process but also energy-intensive and requires stringent operating conditions. Furthermore, the system still requires the introduction of the noble metal Pt as a key co-catalyst to achieve high hydrogen production efficiency, which increases the overall cost of the material system and reduces the feasibility of its industrial application.

[0005] In recent years, organic / inorganic heterojunctions constructed from organic semiconductors and TiO2 have shown broad prospects in the field of photocatalytic hydrogen evolution. Organic components, represented by conjugated polymers (CPs) with strong visible light absorption and tunable photoelectric properties (such as PPy, PANI, PFBTD, P3HT, BBT, PFN, etc.), can significantly broaden the light absorption range, promote photogenerated carrier separation, and optimize the interface structure after coupling with inorganic semiconductor nanoparticles or nanosheets, thereby improving photocatalytic performance. However, the TiO2 / CPs system also has many limitations: it generally requires a high loading (5–30 wt%), which can easily lead to the covering of active sites on the inorganic semiconductor surface and reflection of incident light, thus reducing light absorption efficiency; at the same time, CPs are prone to photo-oxidative degradation when directly exposed to light, resulting in decreased stability; the poor interfacial wettability of most CPs weakens the adsorption and activation capacity of reactants on the catalyst surface; and noble metal co-catalysts are usually required (typically 1–5 wt%), which not only increases cost but also brings potential environmental risks.

[0006] Therefore, developing a TiO2-based photocatalytic system that only loads a very small amount of CPs and can exhibit excellent photocatalytic hydrogen production performance without the need for precious metal co-catalysts is of great significance for reducing the cost of photocatalytic hydrogen production and promoting its practical application. Summary of the Invention

[0007] This application provides a conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst, its preparation method, and its application, aiming to solve the technical problems of existing photocatalysts requiring large amounts of CPs, the introduction of noble metals as co-catalysts, complex preparation processes, and high costs. The photocatalyst of this application exhibits excellent photocatalytic hydrogen production performance with only a very small amount of CPEs loaded and without the need for noble metal co-catalysts.

[0008] To achieve the above objectives, the present application adopts the following technical solution.

[0009] A first aspect of this application provides a method for preparing a conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst, comprising: S1, Pluronic F127 is dissolved in tetrahydrofuran to obtain a homogeneous solution; glacial acetic acid and hydrochloric acid are added to the solution and stirred until homogeneous to obtain the precursor solution; Tetrabutyl titanate was quickly added to the precursor solution and stirred until homogeneous. Then the solvent was removed and the solution was crystallized in situ. The solid phase was collected and calcined to obtain mesoporous titanium dioxide. S2, the conjugated polyelectrolyte is dispersed in a solvent, then mesoporous titanium dioxide is added for self-assembly, the solvent is removed, and the conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst is obtained.

[0010] Preferably, the conjugated polyelectrolyte includes any one of PFBT-CPE, PFN-Br, or PCP-2F-Li; The solvent is methanol.

[0011] Preferably, the concentration of Pluronic F127 in the homogenized solution is 0.8~3.2 g / mL.

[0012] Preferably, the ratio of Pluronic F127, glacial acetic acid, hydrochloric acid and tetrabutyl titanate is 0.8~3.2g:1.2~5mL:0.75~3ml:1.7~7g.

[0013] Preferably, the mass ratio of the conjugated polyelectrolyte to mesoporous titanium dioxide is 0.25~30:100.

[0014] Preferably, the solvent removal specifically involves heating at 40-60°C for 20-28 hours to evaporate the solvent and obtain a hydrogel. And / or, The calcination temperature is 300~400℃, and the time is 90~360min; And / or, The in-situ crystallization temperature is 40~100℃, and the reaction time is 8~30h.

[0015] A second aspect of this application provides a conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst prepared by the above method.

[0016] Preferably, the conjugated polyelectrolyte is uniformly distributed in the mesoporous nanochannels of the mesoporous titanium dioxide nanomaterials; the loading of the conjugated polyelectrolyte is 0.25~4wt%.

[0017] A third aspect of this application provides the application of the aforementioned conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst in visible light water splitting for hydrogen production.

[0018] Preferably, its catalytic visible light water splitting for hydrogen production does not require a precious metal co-catalyst.

[0019] Compared with the prior art, the beneficial effects of this application are as follows: The composite photocatalyst system prepared in this application exhibits a significant nanoconfined effect, enabling CPEs to be uniformly distributed within the mesoporous nanochannels of meso-TiO2, thereby forming a stable and efficient interfacial charge transport structure. This structure broadens the optical absorption range of the material and enhances its visible light response. Simultaneously, the nanoconfined structure facilitates the effective separation and rapid migration of photogenerated electron-hole pairs, significantly improving the photocatalytic reaction efficiency. Compared to single TiO2 photocatalysts, the composite photocatalyst prepared in this application demonstrates a wider light response range and superior photocatalytic water splitting for hydrogen production. It can fully leverage the photosensitization and charge transport advantages of CPEs under extremely low loading conditions (only 0.25~4 wt%) and achieve excellent photocatalytic hydrogen production performance without the need for noble metal (Pt, Rh, etc.) co-catalysts.

[0020] The composite photocatalyst of this application exhibits a synergistic enhancement effect: on the one hand, the mesoporous nanochannels can induce multiple scattering and reflection of incident light within the channels, thereby significantly improving the material's light utilization efficiency; on the other hand, the confined environment effectively avoids the photocorrosion problem caused by direct exposure of CPEs to light, thus improving the structural stability of the system. Simultaneously, an effective type II heterojunction can be constructed between CPEs and meso-TiO2, promoting efficient exciton dissociation under the synergistic effect of the nanoconfinement effect, and accelerating the separation and directional migration of photogenerated electrons and holes at the interface, increasing carrier mobility and expanding the light absorption range, significantly improving the overall photocatalytic reaction kinetics. Furthermore, the ionized side chains of CPEs endow the material with good hydrophilicity and interfacial wettability, enabling it to achieve superior dispersibility and reactant contact efficiency in aqueous reaction systems, thereby further enhancing the catalytic reaction process.

[0021] The preparation method described in this application is simple, mild, and has a high overall yield, effectively reducing energy consumption and production costs while ensuring material performance. Furthermore, it does not use large amounts of toxic or hazardous reagents, making the entire process greener, safer, and more environmentally friendly, in line with current requirements for green chemistry and sustainable development, and possessing good potential for large-scale production and widespread application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1SEM images of the meso-TiO2 nanoparticles and CPEs / meso-TiO2 composite photocatalyst prepared in Example 2; Figure 2 Transmission electron microscopy (TEM) images of the meso-TiO2 nanoparticles and CPEs / meso-TiO2 composite photocatalyst prepared in Example 2; Figure 3 EDX spectra of meso-TiO2 nanoparticles and CPEs / meso-TiO2 composite photocatalyst prepared in Example 2; Figure 4 Line scan EDX spectrum of the CPEs / meso-TiO2 composite photocatalyst prepared in Example 2; Figure 5 XRD patterns of the meso-TiO2 nanoparticles of Example 2, the composite photocatalysts of Examples 1-5 and Comparative Example 1; Figure 6 The meso-TiO2 nanoparticles of Example 2, and the composite photocatalysts of Example 2 and Comparative Example 1. 1 Hss NMR spectrum; Figure 7 The UV-Vis diffuse reflectance (UV-vis DRS) spectra of PFN-Br, PFN and meso-TiO2, Example 2, Comparative Example 1, and Comparative Example 1 are shown. Figure 8 The UV-Vis diffuse reflectance spectra (UV-vis DRS) of Examples 1 to 5 are shown below; Figure 9 The graph shows the N2 adsorption-desorption test results of the meso-TiO2 nanoparticles of Example 2, and the composite photocatalysts of Example 2 and Comparative Example 2. Figure 10 The graph shows the hydrogen production performance test results of the meso-TiO2 nanoparticles of Example 2, and the composite photocatalysts of Example 2, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0026] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0028] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0029] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0030] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0032] This application constructs a CPEs / meso-TiO2 composite photocatalyst with nanoconfined characteristics by using conjugated polyelectrolytes (CPEs) as functional guest molecules and mesoporous titanium dioxide (meso-TiO2) with a three-dimensional interconnected mesoporous nanochannel structure as the main framework, anchoring CPEs within the mesoporous nanochannels. The specific preparation method includes: S1, Pluronic F127 is dissolved in tetrahydrofuran to obtain a homogeneous solution; glacial acetic acid and hydrochloric acid are added to the solution and stirred until homogeneous to obtain the precursor solution; Tetrabutyl titanate was quickly added to the precursor solution and stirred until homogeneous. Then the solvent was removed and the solution was crystallized in situ. The solid phase was collected and calcined to obtain mesoporous titanium dioxide. In this application, the concentration of Pluronic F127 in the homogenized solution is preferably 0.8~3.2g / mL; the ratio of Pluronic F127, glacial acetic acid, hydrochloric acid and tetrabutyl titanate is 0.8~3.2g:1.2~5mL:0.75~3mL:1.7~7g.

[0033] In this application, the glacial acetic acid is AR grade; the hydrochloric acid is commercially available hydrochloric acid, preferably AR grade or electronic grade, with a concentration of 36-38 wt%.

[0034] In this application, the solvent removal specifically involves: heating at 40~60℃ for 20~28h to evaporate the solvent and obtain a hydrogel; The hydrogel is crystallized in situ to obtain a precursor; the preferred temperature for in-situ crystallization is 40-100℃, and the preferred reaction time is 8-30 h. After in-situ crystallization, the precipitate (i.e., the precursor) is collected by filtration or vacuum filtration and then calcined to obtain mesoporous titanium dioxide. The preferred calcination temperature is 300-400℃, and the preferred time is 90-360 min.

[0035] In this application, the stirring rate is preferably 100~600 r / min, and the stirring time is preferably 10~60 min.

[0036] S2, a conjugated polyelectrolyte is dispersed in a solvent, then mesoporous titanium dioxide is added for self-assembly, and the solvent is removed to obtain a conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst. The solvent is methanol.

[0037] In this application, the conjugated polyelectrolyte includes any one of PFBT-CPE, PFN-Br, or PCP-2F-Li; Among them, PFBT-CPE is poly[9,9-alternating-(6'-N,N,N-trimethylammonium)hexyl)fluorene-4,7-(2,1,3-benzothiadiazole)dibromide]; PFN-Br is poly[9,9-dioctyl-9',9'-di[3-(ethyl(dimethyl)ammonium)propyl]][2,2'-bi-9H-fluorene]-7,7'-dibromo; PCP-2F-Li is a polylithium [2,2'-(2-(2,2'-difluorosubstituted derivative 4'-methyl-[1,1'-biphenyl]-4-yl))-6-methyl-5-heptenone-2-4H-cyclopentadienyl[2,1-b:3,4-b']dithiophene-4,4-diyl)bis(ethane-1-sulfonate)].

[0038] In this application, the preferred mass ratio of the conjugated polyelectrolyte to mesoporous titanium dioxide is 0.25~4:100.

[0039] The preparation method described in this application is simple, mild, and has a high overall yield, effectively reducing energy consumption and production costs while ensuring material performance. Furthermore, it does not use large amounts of toxic or hazardous reagents, making the entire process greener, safer, and more environmentally friendly, in line with current requirements for green chemistry and sustainable development, and possessing good potential for large-scale production and widespread application.

[0040] The conjugated polyelectrolyte / mesoporous titanium dioxide composite photocatalyst prepared in this application has the conjugated polyelectrolyte uniformly distributed within the mesoporous nanochannels of the mesoporous titanium dioxide, thus exhibiting a significant nanoconfining effect and forming a stable and efficient interfacial charge transport structure. This structure can broaden the optical absorption range of the material and enhance its visible light response. Simultaneously, the nanoconfined structure of the conjugated polyelectrolyte / mesoporous titanium dioxide composite photocatalyst of this application facilitates the effective separation and rapid migration of photogenerated electron-hole pairs, thereby significantly improving the photocatalytic reaction efficiency.

[0041] It should be noted that the composite photocatalyst of this application exhibits a synergistic enhancement effect: on the one hand, the mesoporous nanochannels can induce multiple scattering and reflection of incident light within the channels, thereby significantly improving the material's light utilization efficiency; on the other hand, the confined environment effectively avoids the photocorrosion problem caused by CPEs being directly exposed to light, thus improving the structural stability of the system. Simultaneously, an effective type II heterojunction can be constructed between CPEs and meso-TiO2, promoting efficient exciton dissociation under the synergistic effect of the nanoconfinement effect, and accelerating the separation and directional migration of photogenerated electrons and holes at the interface, increasing carrier mobility and expanding the visible light absorption range, significantly improving the overall photocatalytic reaction kinetics. Furthermore, the ionized side chains of CPEs endow the material with good hydrophilicity and interfacial wettability, enabling it to achieve superior dispersibility and reactant contact efficiency in aqueous reaction systems, thereby further enhancing the catalytic reaction process.

[0042] The conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst of this application achieves precise control over its spatial distribution and interface structure by introducing the active component into a confined space. This not only effectively avoids the surface shading effect caused by high loading, but also fully leverages the photosensitization and charge transport advantages of CPEs under extremely low loading conditions (only 0.25~4wt%), achieving excellent photocatalytic hydrogen production performance without the need for precious metal co-catalysts.

[0043] The composite photocatalyst of this application can be used for catalytic visible light water splitting to produce hydrogen. Compared with the traditional single TiO2 photocatalyst, the composite photocatalyst of this application exhibits a wider visible light response range and better photocatalytic water splitting to produce hydrogen. In practical applications, it does not need to rely on noble metals (Pt, Rh, etc.) as co-catalysts to exhibit good photocatalytic performance.

[0044] The present application will be further described below through specific embodiments.

[0045] In this example, the raw material Pluronic F127 was purchased from Sigma-Aldrich and has the molecular formula (CH6O·C2H4O)x.

[0046] Example 1 This embodiment provides a method for preparing a CPEs / meso-TiO2 composite photocatalyst, including: S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.5 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 30 min, and then placed in an oven at 45 °C for 24 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; The oven temperature was then raised to 80℃ and maintained for 15 hours to induce in-situ crystallization of the hydrogel. The precipitate, i.e., the precursor, was collected. The precursor was placed in a muffle furnace, heated to 400℃ at a heating rate of 1℃ / min, and calcined for 3 hours to obtain meso-TiO2 nanoparticles.

[0047] S2, PFN-Br and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 0.25 wt%, and self-assembled under light-protected conditions with mechanical stirring at 500 r / min for 24 h. The solvent was then evaporated to obtain the CPEs / meso-TiO2 composite photocatalyst.

[0048] Example 2 The difference between Example 2 and Example 1 is that in Example 2, PFN-Br and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 0.5 wt%, while the rest were the same as in Example 1.

[0049] Example 3 The difference between Example 3 and Example 1 is that in S2, PFN-Br and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 1 wt%, while the rest were the same as in Example 1.

[0050] Example 4 The difference between Example 4 and Example 1 is that in S2, PFN-Br and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 2 wt%, while the rest were the same as in Example 1.

[0051] Example 5 The difference between Example 5 and Example 1 is that in S2, PFN-Br and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 4 wt%, while the rest were the same as in Example 1.

[0052] Example 6 The difference between Example 6 and Example 2 is that the amount of Pluronic F127 used in S1 is 0.8g, and the concentration of Pluronic F127 in the homogenized solution is 0.8g / mL. All other aspects are the same as in Example 2.

[0053] Example 7 The difference between Example 7 and Example 2 is that the amount of Pluronic F127 used in S1 is 3.2g, and the concentration of Pluronic F127 in the homogenized solution is 1.6g / mL. All other aspects are the same as in Example 2.

[0054] Example 8 The difference between Example 8 and Example 2 is that the amount of glacial acetic acid used in S1 is 3.6 mL and the amount of hydrochloric acid used is 2 mL, while the rest are the same as in Example 2.

[0055] Example 9 The difference between Example 9 and Example 2 is that the amount of Pluronic F127 used in S1 is 2.4g, the concentration of Pluronic F127 in the homogenized solution is 1.6g / mL, and the amount of hydrochloric acid used is 1.2mL. All other aspects are the same as in Example 2.

[0056] Example 10 The difference between Example 10 and Example 2 is that the amount of glacial acetic acid used in S1 is 3.6 mL and the amount of hydrochloric acid used is 3 mL, while the rest are the same as in Example 2.

[0057] Example 11 S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.2 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 60 min, and then placed in an oven at 40 °C for 48 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; the rest was the same as in Example 2.

[0058] S2 is the same as in Example 2.

[0059] Example 12 S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.2 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 60 min, and then placed in an oven at 45 °C for 24 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; The oven temperature was then raised to 80℃ and maintained for 30 hours to induce in-situ crystallization of the hydrogel, and the precipitate was collected as the precursor. The precursor was placed in a muffle furnace, heated to 400℃ at a heating rate of 1℃ / min, and calcined for 3 hours to obtain meso-TiO2 nanoparticles.

[0060] S2 is the same as in Example 2.

[0061] Example 13 S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.2 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 60 min, and then placed in an oven at 45 °C for 24 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; the rest was the same as in Example 2.

[0062] S2 differs from Example 2 in that the self-assembly time is 36 hours, while the rest is the same as Example 2.

[0063] Example 14 S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.2 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 60 min, and then placed in an oven at 45 °C for 24 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; The oven temperature was then raised to 80℃ and maintained for 30 hours to induce in-situ crystallization of the hydrogel, and the precipitate was collected as the precursor. The precursor was placed in a muffle furnace, heated to 400℃ at a heating rate of 1℃ / min, and calcined for 3 hours to obtain meso-TiO2 nanoparticles.

[0064] S2 differs from Example 2 in that the self-assembly time is 48 hours, while the rest is the same as Example 2.

[0065] Example 15 S1, 1.6 g of Pluronic F127 was dissolved in 10 mL of tetrahydrofuran solution to form a homogeneous solution; 2.4 mL of glacial acetic acid and 1.2 mL of concentrated hydrochloric acid were added dropwise to the homogeneous solution while stirring continuously; then 3.4 g of tetrabutyl titanate was added and stirred for 60 min, and then placed in an oven at 45 °C for 24 h to allow the tetrahydrofuran and water molecules to slowly evaporate and gradually form a pale yellow hydrogel; The oven temperature was then raised to 80℃ and maintained for 30 hours to induce in-situ crystallization of the hydrogel, and the precipitate was collected as the precursor. The precursor was placed in a muffle furnace, heated to 400℃ at a heating rate of 2℃ / min, and calcined for 3 hours to obtain meso-TiO2 nanoparticles.

[0066] S2 is the same as in Example 2.

[0067] Comparative Example 1 S1 is the same as in Example 2; S2, PFN and meso-TiO2 nanoparticles were dissolved in 20 mL of methanol at a relative mass ratio of 0.5 wt%, and self-assembled under light-protected conditions with mechanical stirring at 500 r / min for 24 h. The solvent was then evaporated to obtain the CPs / meso-TiO2 composite photocatalyst.

[0068] Comparative Example 2 S1 is the same as in Example 2; S2, 0.5 mg PFN-Br and 100 mg meso-TiO2 nanoparticles were physically mixed by grinding to obtain CPEs / meso-TiO2 composite photocatalyst.

[0069] The microscopic morphology and performance evaluation of the CPEs / meso-TiO2 composite photocatalysts prepared in the embodiments and comparative examples of this application are as follows: Part 1: Microscopic Morphology Analysis 1. Scanning electron microscopy was performed on the meso-TiO2 nanoparticles and CPEs / meso-TiO2 composite photocatalyst prepared in Example 2. The results are as follows: Figure 1 As shown. Among them, Figure 1Figure a shows the SEM image of meso-TiO2 nanoparticles, and Figure b shows the SEM image of the CPEs / meso-TiO2 composite photocatalyst.

[0070] from Figure 1 It can be seen that meso-TiO2 nanoparticles are irregular fine nanoparticles. The CPEs / meso-TiO2 composite photocatalyst retains the irregular fine nanoparticles of meso-TiO2, indicating that the introduction of PFN-Br did not change the overall microstructure of meso-TiO2.

[0071] 2. The meso-TiO2 nanoparticles prepared in Example 2 and the CPEs / meso-TiO2 composite photocatalyst were examined by transmission electron microscopy, and the results are as follows: Figure 2 As shown. Among them, Figure 2 Image c in the middle is a transmission electron microscope image of meso-TiO2 nanoparticles; Figure 2 The middle image (d) is a high-resolution transmission electron microscope image of meso-TiO2 nanoparticles; Figure 2 Figure e shows a transmission electron microscope (TEM) image of the CPEs / meso-TiO2 composite photocatalyst.

[0072] from Figure 2 It is known that meso-TiO2 nanoparticles are composed of nanoparticles with an average particle size of approximately 44 nm, and they form well-structured, interconnected mesoporous nanochannels with an average pore size of approximately 11 nm. Furthermore, the meso-TiO2 nanoparticles exhibit clear lattice fringes and a crystal interplanar spacing of 0.35 nm, corresponding to the (101) crystal plane of anatase TiO2, indicating that meso-TiO2 has good crystallinity. The CPEs / meso-TiO2 composite photocatalyst shows a similar morphology to the meso-TiO2 nanoparticles, and PFN-Br is observed to be uniformly dispersed as nanodots of approximately 1 nm in the surface of the meso-TiO2 nanoparticles and confined within the meso-TiO2 mesoporous nanochannels.

[0073] 3. EDX energy dispersive spectroscopy was performed on the meso-TiO2 nanoparticles prepared in Example 2 and the CPEs / meso-TiO2 composite photocatalyst. The results are as follows: Figure 3 As shown. Among them, Figure 3 Figure f shows the test results for meso-TiO2 nanoparticles. Figure 3 Figure g shows the test results of the CPEs / meso-TiO2 composite photocatalyst.

[0074] from Figure 3The elemental mapping results show that the characteristic elements (C, N and Br) of PFN-Br are uniformly distributed in the CPEs / meso-TiO2 composite catalyst, which confirms the successful construction of the CPEs / meso-TiO2 nanocomposite material.

[0075] 4. Line scan EDX spectroscopy was performed on the CPEs / meso-TiO2 composite photocatalyst prepared in Example 2, and the results are as follows: Figure 4 As shown.

[0076] from Figure 4 It can be seen that the N element signal inside the mesoporous nanochannel of the CPEs / meso-TiO2 composite catalyst is significantly stronger than that on the outer surface. This indicates that PFN-Br is preferentially confined inside the mesoporous nanochannel of meso-TiO2, rather than loaded on the outer surface of meso-TiO2.

[0077] 5. XRD tests were performed on the meso-TiO2 nanoparticles of Example 2, the composite photocatalysts of Examples 1-5, and Comparative Example 1. The results are as follows: Figure 5 As shown.

[0078] from Figure 5 The diffraction peaks at 25.3°, 37.7°, 48.0°, 54.0°, 55.1°, and 62.6° correspond to the (101), (004), (200), (105), (211), and (204) crystal planes of anatase TiO2 (space group I41 / amd, JCPDS No. 21-1272), respectively. Compared with single nano-meso-TiO2, the XRD pattern of the composite photocatalyst did not show significant changes, indicating that the introduction of amorphous PFN-Br or PFN did not destroy the crystal structure of the inorganic components. This result is consistent with the analysis conclusions of SEM and TEM, further proving that the crystal structure of TiO2 remains stable during the composite process.

[0079] 6. The meso-TiO2 nanoparticles of Example 2, the composite photocatalysts of Example 2 and Comparative Example 1 were subjected to... 1 Hss NMR detection, the results are as follows Figure 6 As shown.

[0080] from Figure 6 It can be seen that due to the loss of all hydroxyl groups on its surface during the calcination process, meso-TiO2... 1The Hss NMR spectrum showed a characteristic peak only at 5.57 ppm, corresponding to surface-adsorbed water. In contrast, the composite photocatalyst of Example 2 showed new characteristic peaks at 1.01, 3.47, and 5.04 ppm, while the composite photocatalyst of Comparative Example 1 showed characteristic peaks at 1.27, 2.17, 3.63, and 4.25 ppm. This indicates that in the composite photocatalysts of Example 2 and Comparative Example 1, PFN-Br or PFN was effectively confined within the meso-TiO2 mesoporous nanochannels, thereby altering the local chemical environment of hydrogen.

[0081] 7. The light absorption performance of the photocatalysts was systematically evaluated using UV-Vis diffuse reflectance spectroscopy (UV-vis DRS). The results showed that both single PFN-Br and PFN exhibited significant absorption peaks at approximately 410 nm, mainly attributed to the characteristic absorption of the fluorene ring structure in their conjugated backbone. Figure 7 As shown in the figure, meso-TiO2 exhibits a characteristic absorption peak at approximately 300 nm. Further comparison reveals that the absorption edges of the composite catalysts all show a significant red shift compared to pure meso-TiO2, indicating an effective extension of their visible light response capability. This is mainly attributed to the excellent light absorption properties of PFN-Br and PFN. However, Example 2, prepared through simple physical mixing, shows a blue shift in its absorption edge compared to pure meso-TiO2, indicating that this method fails to achieve effective coupling at the interface level, thus making it difficult to improve the optical response performance of the material.

[0082] 8. The light absorption performance of the composite photocatalysts with different PFN-Br loadings in Examples 1 to 5 was evaluated by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Figure 8 As shown in the figure, the results indicate that the overall light absorption capacity of the composite material significantly increases with the gradual increase of PFN-Br loading. This is attributed to both the enhanced intrinsic light-harvesting ability resulting from the increased PFN-Br content and the multiple scattering effect of the mesoporous nanochannel structure on incident light, thereby further improving light utilization efficiency.

[0083] 9. N2 adsorption-desorption tests were performed on the meso-TiO2 nanoparticles of Example 2, the composite photocatalysts of Example 2 and Comparative Example 2. The specific surface area, pore volume, and average pore size of the samples were analyzed, and the results are as follows: Figure 9 As shown.

[0084] from Figure 9 It can be seen that all three samples exhibit typical type IV isotherms accompanied by type H3 hysteresis loops, indicating that all samples possess mesoporous structure characteristics. For meso-TiO2, its specific surface area, pore volume, and average pore diameter are 77.40 μm.2 / g, 0.41 cm 3 / g and 17.22 nm. Compared with meso-TiO2, the specific surface area, pore volume, and average pore size of the composite photocatalyst in Example 2 were reduced to 48.94 nm. 2 / g, 0.33 cm 3 The specific surface area and pore volume were 16.93 nm, mainly due to the fact that PFN-Br nanodots were confined within the mesoporous nanochannels of meso-TiO2, occupying part of the pore space, thus reducing its specific surface area and pore volume. Compared with meso-TiO2, the CPEs / meso-TiO2 obtained by mixing meso-TiO2 with 0.5 wt% PFN-Br through simple physical grinding in Comparative Example 2 showed that its specific surface area, pore volume, and average pore size were all increased to 81.01 nm. 2 / g, 0.47cm 3 / g and 18.89nm. This is mainly attributed to the fact that PFN-Br dispersed on the surface of meso-TiO2 effectively inhibits the aggregation between meso-TiO2 nanoparticles, thereby leading to an increase in its specific surface area and pore volume.

[0085] Part Two: Catalytic Hydrogen Production Performance Testing The hydrogen production performance of the meso-TiO2 nanoparticles of Example 2, as well as the composite photocatalysts of Example 2, Comparative Example 1, and Comparative Example 2, was studied using the following methods: A xenon lamp was used as the hydrogen production light source, with a wavelength range of λ ≥ 320 nm. The composite photocatalyst dosage was 0.2 g / L, the sacrificial agent was 20 mL triethanolamine, and 80 mL water was added. The reaction cell was evacuated, and argon was used as the carrier gas. The generated H2 was detected by gas chromatography. A hydrogen production experiment was conducted for 4 hours, and the hydrogen data in the system was collected every 1 hour. The test results are as follows: Figure 10 As shown, the horizontal axis represents time, and the vertical axis represents hydrogen production.

[0086] from Figure 10 It can be seen that the hydrogen production rate of the meso-TiO2 nanoparticles in Example 2 was only 193.25 μmol·g within 4 hours. - 1 h -1 However, the hydrogen production rate of the PFN-Br / meso-TiO2 composite photocatalyst obtained through self-assembly reached 3414.73 μmol·g. -1 h -1 This is 17.67 times that of single meso-TiO2. As a control group for Example 2, the photocatalytic hydrogen evolution rate of the composite photocatalyst in Comparative Example 1 was only 2344.36 μmol·g⁻¹. -1 ·h -1This is mainly attributed to the fact that PFN exhibits poorer hydrophilicity compared to PFN-Br, which limits the effective adsorption and activation of reactants on the catalyst surface, thus affecting the photocatalytic reaction efficiency. Furthermore, the PFN-Br / meso-TiO2 composite photocatalyst in Comparative Example 2, prepared by physical grinding, only achieved a hydrogen production rate of 242.08 g / L within 4 hours. -1 h -1 This indicates that in Example 2, PFN-Br is preferentially confined within the mesoporous nanochannels of meso-TiO2 rather than loaded on the surface of meso-TiO2, thereby forming a highly efficient organic / inorganic heterojunction nanoreactor, promoting the separation and migration of photogenerated carriers, and thus possessing excellent catalytic efficiency without the need for noble metal loading.

[0087] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A method for preparing a conjugated polyelectrolyte / mesoporous nanotitania composite photocatalyst, characterized in that, include: S1, Pluronic F127 is dissolved in tetrahydrofuran to obtain a homogeneous solution; glacial acetic acid and hydrochloric acid are added to the solution and stirred until homogeneous to obtain the precursor solution; Tetrabutyl titanate was quickly added to the precursor solution, stirred until homogeneous, and then the solvent was removed and crystallized in situ. The solid phase was collected and calcined to obtain mesoporous titanium dioxide. S2, the conjugated polyelectrolyte is dispersed in a solvent, then mesoporous titanium dioxide is added for self-assembly, the solvent is removed, and the conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst is obtained.

2. The production method according to claim 1, characterized by, The conjugated polyelectrolyte includes any one of PFBT-CPE, PFN-Br, or PCP-2F-Li; The solvent is methanol.

3. The preparation method according to claim 1, characterized in that, The concentration of Pluronic F127 in the homogenized solution is 0.8~3.2 g / mL.

4. The method of claim 1, wherein, The ratio of Pluronic F127, glacial acetic acid, hydrochloric acid and tetrabutyl titanate is 0.8~3.2g:1.2~5mL:0.75~3ml:1.7~7g.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the conjugated polyelectrolyte to mesoporous titanium dioxide is 0.25~4:

100.

6. The preparation method according to claim 1, characterized in that, The solvent removal process specifically involves heating at 40-60°C for 20-28 hours to evaporate the solvent and obtain a hydrogel. And / or, The calcination temperature is 300~400℃, and the time is 90~360min; And / or, The in-situ crystallization temperature is 40~100℃, and the reaction time is 8~30h.

7. The conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst prepared by the preparation method according to any one of claims 1-6.

8. The conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst according to claim 7, characterized in that, The conjugated polyelectrolyte is uniformly distributed in the mesoporous nanochannels of the mesoporous titanium dioxide; the loading of the conjugated polyelectrolyte is 0.25~4wt%.

9. The application of the conjugated polyelectrolyte / mesoporous nano-titanium dioxide composite photocatalyst according to claim 7 or 8 in visible light water splitting for hydrogen production.

10. The application according to claim 9, characterized in that, Its catalytic visible light water splitting for hydrogen production requires no precious metal co-catalyst.

Images