An amphiphilic supramolecular assembly photocatalyst, a preparation method and use thereof

Abstract

The application discloses an amphiphilic supramolecular assembly photocatalyst in the field of organic semiconductor photocatalysis, which uses a hydrophilic peptide chain modified perylene diimide derivative as an assembly unit, utilizes the pH response characteristics of multiple carboxyl groups and imidazole groups in the peptide chain to precisely control the micro-ordered structure of the supramolecular assembly and the micro-environment of the surface and interface, and further optimizes the photoelectric performance and photocatalytic efficiency. The amphiphilic supramolecular material constructed by the pH regulation self-assembly method of the application can realize efficient photocatalytic generation of H2O2 in a wide pH range (3-11.4), and the reaction rate can reach 1.56 mmol g ‑1 h ‑1 , which is 9 times that of the non-amphiphilic PDI supramolecular material. The catalyst has the advantages of easy dispersion in a water system, easy recovery, no need for an organic sacrificial agent, wide pH adaptability, visible light response and the like.

Description

Technical Field

[0001] This invention relates to a semiconductor photocatalyst, particularly an amphiphilic supramolecular material constructed by a self-assembly method, its preparation method, and its application in photocatalytic hydrogen peroxide production. Background Technology

[0002] Hydrogen peroxide (H2O2), as a clean oxidant and potential energy carrier, has wide applications in environmental remediation, chemical synthesis, and biomedicine. Currently, the dominant industrial process, anthraquinone (market share >95%), heavily relies on precious metal catalysts and organic solvents, resulting in high energy consumption, numerous steps, difficulty in catalyst recovery, and poor environmental adaptability. Photocatalytic H2O2 production technology, using water and oxygen as raw materials and sunlight as the sole driving force, is widely recognized as a promising green synthetic route. Polycyclic aromatic hydrocarbons (PAHs) conjugated organic semiconductor photocatalysts possess excellent visible light absorption and carrier transport performance, are low in cost, and effectively overcome the wide band gap of inorganic photocatalysts. However, due to their rigid molecular framework and strong intermolecular π-π stacking interactions, PAHs often exhibit poor solubility in organic solvents; in aqueous systems, strong hydrophobic effects further complicate dissolution, making effective dispersion in water difficult. Meanwhile, this strong tendency to aggregate makes it extremely difficult for PAHs to form long-range ordered structures through self-assembly, resulting in hindered carrier migration and severe charge recombination. Currently, the main strategies for improving the dispersibility of PAHs in aqueous systems include: using organic solvents for dispersion assistance, or covalently modifying them by introducing polyethylene glycol chains or dendritic hydrophilic groups to enhance water solubility. For example, Chinese patent CN120460019A uses isopropanol to help disperse organic photocatalysts in aqueous systems. While the latter type of molecular modification strategy helps improve the water solubility of PAHs, it is generally difficult to induce their assemblies to form long-range ordered structures.

[0003] As a class of n-type PAH semiconductors, perylene imide derivatives (PDIs) supramolecular photocatalysts have been extensively studied due to their potential in the efficient production of H2O2. Researchers designed and synthesized three bay-position substituted PDI molecules (H2PDI, 2Br-H2PDI, and 4CH3CH2O-H2PDI), which self-assembled to form one-dimensional nanorods, two-dimensional nanosheets, and zero-dimensional nanoparticles, respectively. Among them, the zero-dimensional nanoparticles 4CH3CH2O-H2PDI achieved a photocatalytic H2O2 production rate of 657.4 μM·g under conditions without a sacrificial agent. -1 ·h -1The yields were 3 times and 4 times that of 2Br-H2PDI and H2PDI, respectively. The efficiency of PDI supramolecular photocatalytic H2O2 production is mainly limited by the kinetic matching of the oxygen reduction reaction (ORR), which is highly dependent on the pH of the system. It is generally believed that a weakly acidic environment (pH 3-5) is more conducive to increasing the yield of H2O2 (O2 + 2H+). + +2e - →H2O2). Therefore, the H2O2 production performance of such supramolecular catalysts under alkaline conditions is often unsatisfactory. Summary of the Invention

[0004] This invention aims to provide an amphiphilic supramolecular assembled photocatalyst, its preparation method and uses. The amphiphilic supramolecular material constructed by pH-controlled self-assembly is used as a photocatalyst to achieve efficient photocatalytic generation of H2O2 over a wide pH range. It has a high reaction rate and the catalyst has the advantages of being easy to disperse and recover in aqueous systems.

[0005] The technical solution to achieve the objective of this invention is as follows: An amphiphilic supramolecular photocatalyst, wherein the photocatalyst is formed by pH-controlled self-assembly of a hydrophilic peptide-modified perylene diimide derivative (HPPDI), possessing a long-range ordered supramolecular structure; the structural formula of the HPPDI is: ; The photocatalyst is uniformly dispersed in the aqueous phase and can catalyze the reduction of oxygen to hydrogen peroxide under visible light irradiation.

[0006] Furthermore, the long-range order of the HPPDI supramolecular structure is regulated by adjusting the pH value of the system, and the resulting photocatalyst exhibits different assembly morphologies and photocatalytic activities under different pH conditions.

[0007] The preparation method of the above-mentioned amphiphilic supramolecular assembled photocatalyst includes the following steps: S1, HPPDI solid is dissolved in chloroform containing trifluoroacetic acid, and then sonicated to obtain a clear solution A; the chloroform solution of trifluoroacetic acid dissociates the HPPDI assembly into unimolecular solutions; S2, take solution A into a sample bottle, remove the solvent and dry it. After drying, the solid is obtained as HPPDI solid with an assembly structure that eliminates the initial metastable state and has a very low degree of molecular stacking. S3, the solid obtained in S2 is dissolved and assembled with sodium hydroxide aqueous solution, and HPPDI assembly solution B is obtained by temperature control stirring and slow cooling; S4. Solution B is diluted with an aqueous medium to adjust the pH value, then sonicated and allowed to stand to obtain HPPDI supramolecular dispersion C.

[0008] Further, gluconolactone (GDL) solid, used for in-situ pH regulation, is added to the supramolecular dispersion C to obtain supramolecular dispersion D; the GDL concentration in the solution is 1.4-20 mM.

[0009] Further, in step S3, the concentration of sodium hydroxide aqueous solution is 10-40 mM; the concentration of HPPDI is 1-5 mM. After dispersion, the solution is first sonicated at 50-60℃ for 20-40 min, then stirred at 350-600 rpm at 60℃ for more than 12 h, and then slowly cooled to room temperature at a rate of 5℃ every 30 min.

[0010] Further, in step S4, the aqueous medium is pure water or BR buffer solution; when using buffer solution, its concentration is 2-10 mM, and its components are phosphoric acid, boric acid and acetic acid; the ultrasonic time is 5-10 min, and the standing time is 12-24 h.

[0011] Further, in step S1, the volume fraction of trifluoroacetic acid in chloroform is 0.2-0.5 vol%; the ultrasonic time is 10-30 min and the frequency is 37 kHz; the concentration of HPPDI in solution A is 10-20 mM; in step S2, the solvent is removed by nitrogen purging, the vacuum drying temperature is 35-65℃, and the drying time is 48-72 h.

[0012] The amphiphilic supramolecular photocatalyst prepared according to the above method is used for photocatalytic production of hydrogen peroxide, including the following steps: (1) Under light-protected conditions, oxygen is continuously introduced into supramolecular dispersion C or supramolecular dispersion D and stirred. (2) Photocatalytic reaction is carried out by irradiating supramolecular dispersion C or supramolecular dispersion D with visible light while introducing oxygen and stirring. (3) Mix the reaction solution obtained in step (2) with potassium titanium oxalate / sulfuric acid solution to develop color, filter, and take the filtrate to obtain hydrogen peroxide color solution.

[0013] Further, in step (1), the concentration of HPPDI supramolecular dispersion is 0.25-2 mM; the stirring speed is 350-800 rpm; the oxygen bubbling time is 20-40 min; in step (2), the visible light is provided by a xenon lamp with a wavelength range of 380-800 nm, a light intensity of 100-325 mW / cm², and an irradiation time of 1-3 h; in step (3), the filter membrane used for filtration is one of MCE, nylon membrane or hydrophilic polyvinylidene fluoride membrane, with a membrane pore size of 0.22-0.45 μm.

[0014] Further, in step (3), the concentration of potassium titanium oxalate in the potassium titanium oxalate / sulfuric acid solution is 0.005-0.010 mol / L; the concentration of sulfuric acid is 1-5 mol / L; and the mixing ratio of the reaction solution to the potassium titanium oxalate / sulfuric acid solution is 1:(0.67-0.34).

[0015] The design principle of the above preparation process is as follows: This invention first uses a chloroform solution containing trifluoroacetic acid to dissociate HPPDI assemblies into unimolecular solutions. After drying, a solid state with extremely low molecular stacking is obtained to eliminate the interference of the initial metastable assembly structure on the subsequent aqueous phase assembly process. Subsequently, sodium hydroxide solution is used to deprotonate the carboxyl groups of HPPDI to enhance water solubility, forming an oligomeric solution under high-temperature stirring. Then, through a thermodynamically controlled process of gradual cooling, a stable and structurally ordered HPPDI supramolecular assembly is finally obtained in the aqueous phase.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The hydrophilic peptide-modified perylene diimide derivative (HPPDI) used in this invention has a peptide chain composed of glutamic acid-glutamic acid-alanine-histidine-β-alanine or aspartic acid-aspartic acid-alanine-histidine-β-alanine. The abundant terminal carboxyl groups greatly enhance the solubility of HPPDI in water and endow the assembly structure with pH responsiveness, while constructing a unique microenvironment at the supramolecular material interface.

[0017] (2) This invention introduces chiral peptide chains and utilizes the synergistic effect of strong directional hydrogen bonds between peptide chains and π-π stacking between PDI rings to induce the formation of a long-range ordered assembly structure with supramolecular chirality. This achieves efficient transport of photogenerated carriers, effectively suppresses charge recombination, and promotes the separation of photogenerated electrons and holes. Under alkaline conditions, the hydrogen peroxide generation rate of this amphiphilic HPPDI supramolecular photocatalyst reaches as high as 1.56 mmol g. -1 h -1 It is 9 times that of non-amphiphilic PDI supramolecular materials.

[0018] (3) The method for preparing hydrogen peroxide based on amphiphilic HPPDI supramolecular photocatalysis provided by this invention has outstanding advantages such as easy dispersion in aqueous systems, no use of precious metals, no need for organic sacrificial agents, easy catalyst recovery, and wide pH adaptability. This method uses O2 as raw material and visible light as energy source at room temperature and pressure. Compared with the industrial anthraquinone method, this invention significantly reduces energy consumption, simplifies the process, and has higher safety. Attached Figure Description

[0019] Figure 1 The process flow diagram for the preparation of amphiphilic HPPDI supramolecular dispersion and its photocatalytic hydrogen peroxide production is shown.

[0020] Figure 2 The results show the supramolecular spectroscopic characteristics of HPPDI. (a) Fluorescence emission spectrum as a function of pH; (b) Circular dichroism chromatogram as a function of pH; (c) pH value as a function of time after adding different masses of GDL solid; and (d) Circular dichroism chromatogram as a function of time after adding GDL. The HPPDI concentration was 0.02 mM in all cases.

[0021] Figure 3 Scanning electron microscope (SEM) images of HPPDI supramolecular assemblies under different pH conditions are shown, with the inset being a transmission electron microscope (TEM) image. The HPPDI concentration was 0.05 mM.

[0022] Figure 4 Cyclic photocurrent response curves of HPPDI supramolecular drop-cast membranes constructed under different pH conditions. The HPPDI concentration was 0.5 mM.

[0023] Figure 5 The photocatalytic hydrogen peroxide production performance of HPPDI supramolecular dispersions under different pH conditions was investigated. (ac) shows the UV-Vis absorption spectra of the solutions at different pH values ​​after color development with potassium titanium oxalate / sulfuric acid; (d) shows the hydrogen peroxide concentration versus illumination time and a control experiment (oxygen-free, light-free, catalyst-free); (e) shows the initial hydrogen peroxide production rate versus pH, compared with the non-amphiphilic PDI supramolecular material A4UP (A4PDI dispersed in water). The HPPDI concentration was 0.5 mM.

[0024] Figure 6 The electron paramagnetic resonance (EPR) spectra of HPPDI supramolecular dispersions are shown, with a DMPO concentration of 50 mM. (a, b) represent the ·OH signals under neutral and alkaline conditions, respectively, in the dark and under light irradiation. (c, d) represent the HOO· signals under neutral and alkaline conditions, respectively, in the light and under light irradiation. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0026] Synthetic route for hydrophilic peptide chain modified perylene diimide derivatives (HPPDI): N-(1-diundecyl)-3,4,9,10-perylenetetracarboxylic acid monoimide (1 eq) and hydrophilic peptide chain -NH2 (1.5-2 eq) were dissolved in imidazole, heated to 120 °C and stirred until homogeneous. Then, a catalyst amount of zinc acetate was added, and the temperature was further increased to 130-140 °C, with stirring for 6-12 h. After the reaction was complete, the mixture was cooled to 60-80 °C, ethanol was added, and the mixture was further cooled to room temperature. Then, 3 M HCl solution was added, and the mixture was stirred overnight. The resulting reaction solution was dialyzed for 2 days. After dialysis, the mixture was filtered under reduced pressure, and the filter cake was washed with pure water until the filtrate was colorless and dried under vacuum. The dried solid was dispersed and washed with dichloromethane and filtered. This process was repeated until the filtrate was colorless. The filter cake was collected and dried under vacuum at 65 °C for 48 h to obtain HPPDI, with the following structural formula:

[0027] HPPDI Synthetic route of hydrophobic peptide chain modified perylene diimide derivative (A4PDI): N-(1-diundecyl)-3,4,9,10-perylenetetracarboxylic acid monoimide (1 eq) and hydrophobic peptide chain -NH2 (2~2.5 eq) were dissolved in imidazole, heated to 120°C and stirred until homogeneous. Then, a catalyst amount of zinc acetate was added, and the temperature was further increased to 130-140°C, with stirring for 6-12 h. After the reaction was complete, the mixture was cooled to 60-80°C, ethanol was added, and the mixture was further cooled to room temperature. Then, 3 M HCl solution was added, and the mixture was stirred overnight. The dried solid was dispersed and washed with dichloromethane and filtered. This process was repeated until the filtrate was colorless. The filter cake was collected and dried under vacuum at 65°C for 48 h to obtain A4PDI, whose structural formula is:

[0028] A4PDI Example 1

[0029] Example 1 illustrates the preparation method of amphiphilic HPPDI supramolecular dispersion and its photocatalytic hydrogen peroxide production steps: The preparation method of HPPDI supramolecular dispersion includes the following steps: S1. Dissolve solid HPPDI in chloroform containing 0.2-0.5 vol% trifluoroacetic acid, and sonicate at room temperature for 10-30 min (frequency 37 kHz) to obtain a clear solution A with an HPPDI concentration of 10-20 mM. S2, take solution A and place it in a sample bottle, purge with nitrogen to remove the solvent, and then vacuum dry at 35-65℃ for 48-72 h to obtain 5-20 mg of HPPDI oligomer solid.

[0030] S3. Add a 1-40 mM sodium hydroxide aqueous solution to the solid obtained in step (2), sonicate at 50-60℃ for 20-40 min, then stir at 350-600 rpm overnight at 60℃ (>12 h), and then slowly cool to room temperature at a rate of 5℃ every 30 min to obtain HPPDI supramolecular solution B with a concentration of 0.2-5 mM.

[0031] S4. Dilute solution B with pure water or BR buffer solution, sonicate for 5-10 min, and let stand for 12-24 h to obtain HPPDI supramolecular dispersion C. The BR buffer solution has a concentration of 1-10 mM and consists of phosphoric acid, boric acid, and acetic acid. If in-situ pH adjustment is required, after dilution with pure water and stabilization by standing, add gluconolactone (GDL) solid to the dispersion to a concentration of 1.4-20 mM to obtain HPPDI supramolecular dispersion D.

[0032] The method for photocatalytic hydrogen peroxide production from the obtained HPPDI supramolecular dispersion (C or D) includes the following steps: (1) Under light-protected conditions, continuously introduce oxygen into HPPDI supramolecular dispersion C or D with a concentration of 0.2-2 mM for 20-40 min and stir at a speed of 350-800 rpm.

[0033] (2) Maintain oxygen flow and stirring, using visible light provided by the xenon lamp (wavelength range 380-800 nm, light intensity 100-325 mW / cm²). 2 Irradiate for 1-3 hours to carry out photocatalytic reaction.

[0034] (3) The reaction solution obtained in step (2) is mixed with potassium titanium oxalate / sulfuric acid solution at a volume ratio of 1:0.34-0.67 for color development. The concentration of potassium titanium oxalate is 0.005-0.010 mol / L, and the concentration of sulfuric acid is 1-5 mol / L. After color development, the solution is filtered through a filter membrane with a pore size of 0.22-0.45 μm. The filter membrane is one of MCE membrane, nylon membrane, or hydrophilic polyvinylidene fluoride membrane. The filtrate is then collected to obtain the hydrogen peroxide color development solution.

[0035] (4) The filter cake obtained by filtration is washed with ultrapure water and then freeze-dried or vacuum-dried at 65°C to recover HPPDI supramolecular photocatalyst. Example 2

[0036] Example 2 demonstrates the effect of pH on the self-assembly behavior of HPPDI.

[0037] 1.6 mg of solid HPPDI was dissolved in 1 mM sodium hydroxide solution to prepare a 0.2 mM HPPDI solution. The solution was sonicated for 15-30 min until the solid was completely dissolved. The solution was then stirred at 50 °C for 3 h, and then slowly cooled to room temperature at a rate of 5 °C every 30 min, with stirring continued overnight to obtain mother liquor 1. Mother liquor 1 was diluted to 0.02 mM with either 1 mM sodium hydroxide solution or BR buffer solution, and sonicated for 5-10 min to obtain HPPDI supramolecular dispersions C at different pH values. Each dispersion was allowed to stand for 2 hours for spectral analysis. Fluorescence emission spectra were measured using a fluorescence spectrometer (F-7000, Hitachi, Japan), with an excitation wavelength of 483 nm, excitation and emission slit widths of 2.5 nm, and optical path lengths of 0.5-1 cm. Circular dichroism (CD) spectra were measured using a circular dichroism spectrometer (J-810, JASCO, Japan), with a response time of 4 s, a bandwidth of 2 nm, and an optical path length of 0.5 cm. To investigate the effect of slowly decreasing the pH of gluconolactone (GDL) on the assembly behavior of HPPDI, stock solution 1 was diluted with 1 mM sodium hydroxide, and then solid GDL was added to achieve concentrations of 1.4, 2.8, and 5.6 mM. CD spectra were recorded every 2 min from the time of addition for a total of 30 min.

[0038] like Figure 2 As can be seen, fluorescence emission peaks appear at 546 nm and 655 nm, which are attributed to the emission peaks of the HPPDI monomer (mon.) and excimer, respectively. With decreasing pH, the intensity of the monomer emission peak initially decreases slowly, then rapidly weakens at pH 6, and approaches equilibrium at pH 4; the intensity of the excimer emission peak initially increases, then rapidly decreases at pH 4. Figure 2 As can be seen from b, the supramolecular assembly exhibits a negative Cotton peak at 496 nm and a positive Cotton peak at 450 nm, indicating that it has formed a left-handed supramolecular chiral assembly. The intensity of the Cotton peak at 496 nm is basically stable above pH 8, begins to decrease sharply at pH 8, and approaches zero at pH 3. Figure 2 As shown in c, after the addition of GDL, the pH of the system decreased slowly over time, and the rate of decrease increased with the increase of GDL dosage. At 30 min, the pH decreased to 8.5 (1.4 mM GDL), 7.4 (2.8 mM GDL), and 4.0 (5.6 mM GDL), respectively. Correspondingly, as... Figure 2As shown in Figure d, the intensity of the 496 nm Cotton peak initially increases and then stabilizes at low GDL concentrations. When the pH of the system decreases significantly (GDL concentration of 5.6 mM), the peak intensity decreases linearly, but the CD value remains higher than that of the supramolecular assembly directly adjusted to the same pH using buffer solution. These results indicate that decreasing pH gradually protonates the carboxylate group, weakens intermolecular electrostatic repulsion, and enhances hydrogen bonding. Under the synergistic effect of π-π stacking and hydrophobicity, the assembly degree of HPPDI increases. However, when the pH approaches or even falls below pKa (approximately 4), excessively strong intermolecular interactions are detrimental to the construction of long-range ordered structures, leading to a weakening of the CD signal. Slow acidification of GDL helps maintain the ordered microstructure of the HPPDI supramolecular structure. Example 3

[0039] Example 3 investigated the effect of pH on the morphology of HPPDI supramolecular assemblies.

[0040] The preparation of the HPPDI supramolecular dispersion was performed according to Example 1. A 1 mM HPPDI supramolecular solution B (5 mM sodium hydroxide concentration) prepared in Example 1 was diluted with water to 0.5 mM to obtain solution C. The solution was sonicated for 5-10 min. 300 μL of solution C was then diluted with 2.5 mM sodium hydroxide solution or a buffer solution to 0.05 mM, sonicated for 5 min, and allowed to stand for 24-72 h to obtain the HPPDI supramolecular dispersion. 14 μL of the dispersion was dropped onto a copper grid, dried, and then its morphology was characterized. For the GDL in-situ controlled system, after dilution with 2.5 mM sodium hydroxide solution, GDL solid was added to a final concentration of 14 mM.

[0041] Depend on Figure 3 It is evident that under alkaline and neutral conditions, HPPDI supramolecular structures primarily exist as vesicles. While vesicles still predominate under acidic conditions, significant aggregation occurs between vesicles. Vesicles obtained through in-situ slow acidification of GDL exhibit better dispersibility than those obtained through direct acidification with buffer solutions. Under acidic conditions, hydrogen bonds readily form between carboxyl groups on the vesicle surface, inducing vesicle aggregation. In contrast, in-situ slow acidification of GDL creates a unique dynamic equilibrium of carboxyl group dissociation at the vesicle interface, thus maintaining better dispersibility. Example 4

[0042] Example 4 investigated the photoelectric response properties of HPPDI supramolecular assemblies constructed under different pH conditions.

[0043] The preparation of the HPPDI supramolecular dispersion was performed according to Example 1. 50 μL of the 5 mM HPPDI supramolecular solution B (sodium hydroxide concentration of 25 mM) obtained in Example 1 was diluted to 0.5 mM with 2.5 mM sodium hydroxide solution or BR buffer solution, sonicated for 5 min, and allowed to stand for 24 h to obtain HPPDI supramolecular dispersion C. 100 μL of dispersion C was uniformly drop-coated onto ITO glass and vacuum-dried at 35 °C for 6 h, followed by further vacuum drying at 65 °C for 24 h to obtain the HPPDI supramolecular / ITO working electrode. Using an electrochemical workstation (Beijing Huake Putian), a 0.1 M sodium sulfate aqueous solution was used as the electrolyte, and a 350 W xenon lamp (BBZW-III, wavelength range 380-800 nm) was used as the light source, with a bias voltage of 0.5 V. A standard three-electrode system was used: HPPDI supramolecular / ITO as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum electrode as the counter electrode. Shine the light source perpendicularly onto the ITO surface, turn off the light source after 20 seconds, and turn it back on after another 20 seconds. Repeat this cycle 4 times. Each data point should be tested at least 4 times.

[0044] like Figure 4 As shown, the photocurrent increases rapidly after illumination and quickly returns to baseline levels after the light source is turned off. With increasing cycle count, the photocurrent intensity shows no significant decrease, indicating that the HPPDI supramolecular exhibits good photoelectric reactivity and cycling stability. The HPPDI supramolecular constructed in a sodium hydroxide-water system (pH 11.4) exhibits a photocurrent density of 1.05 μA / cm². 2 As pH decreases, the photocurrent density decreases significantly, reaching only 0.17 μA / cm at pH 3. 2 The HPPDI supramolecular structure constructed using an in-situ pH-lowering GDL system can achieve a photocurrent density of 1.15 μA / cm². 2 The pH value was 6.8 times higher than that of supramolecular structures prepared in buffer solutions, indicating that the in-situ slow pH reduction strategy is beneficial for constructing more efficient photoelectric conversion supramolecular structures. Example 5

[0045] Example 5 compared the photocatalytic hydrogen peroxide production performance of HPPDI supramolecular assemblies constructed under different pH conditions, and compared it with the photocatalytic efficiency of non-amphiphilic supramolecular assemblies.

[0046] The preparation of the HPPDI supramolecular dispersion and the steps for photocatalytic hydrogen peroxide production are the same as in Example 1. The difference is that the concentration in supramolecular dispersions C and D is 0.5 mM. The visible light intensity is 325 mW / cm². 2 The irradiation time is 60 minutes.

[0047] Depend on Figure 5As can be seen from the results, the HPPDI supramolecular reaction solutions constructed under different pH conditions and the GDL slow acidification system all exhibited a single peak absorption at 405 nm after color development. This peak is attributed to the absorption peak of the complex formed by potassium titanium oxalate and H2O2, indicating that the HPPDI supramolecular structures constructed under various conditions can effectively photocatalyze the generation of H2O2. Figure 5 As can be seen, the H2O2 concentration in all systems increased with increasing light exposure time, with the increase rate in the order of GDL > pH 11.4 > pH 3. The control experiment results show that no H2O2 was generated under light conditions without oxygen or photocatalyst, or in the absence of light, confirming that light and photocatalyst are necessary conditions for H2O2 production, and that H2O2 originates from the oxygen reduction reaction (ORR). Linear fitting of the initial time period data (…) Figure 5 (Middle dashed line) to obtain the initial reaction rate of photocatalytic H2O2 production, such as Figure 5 As shown in e, the initial rate of H2O2 production by the supramolecular assembly constructed at pH 11.4 was 1.08 mmol g. -1 h -1 The supramolecular production rate was lowest at pH 3, at 0.89 mmol g. -1 h -1 The supramolecular initial rate of GDL slow acidification was the highest, reaching 1.56 mmol g. -1 h -1 The rates were 1.4 times higher at pH 11.4 and 1.8 times higher at pH 3, respectively. In contrast, the H2O2 production rate of the amphiphilic HPPDI supramolecular under any construction conditions was higher than that of the weakly amphiphilic / non-amphiphilic A4PDI supramolecular, with the highest increase reaching 9 times. Example 6

[0048] Example 6 investigated the types of reactive oxygen species generated in HPPDI supramolecular dispersions under light irradiation.

[0049] The preparation of the HPPDI supramolecular dispersion was the same as in Example 1, except that: one portion of the supramolecular dispersion C prepared in Example 1 was distilled under reduced pressure to obtain solid sample 1 (Alkali); the other portion was dialyzed until the pH was neutral, and then distilled under reduced pressure to obtain solid sample 2 (neutral). The obtained solid samples were ultrasonically dispersed in their respective solvents: water was used to detect hydroxyl radicals (·OH); methanol / water was used to detect superoxide anion radicals / hydroperoxide radicals (·O2). - / HOO·。 Before testing, 5,5-dimethyl-1-pyrrolino-N-oxide (DMPO) was added at a concentration of 50 mM. EPR spectra before and after illumination were recorded using a paramagnetic resonance spectrometer (Bruker BioSpin GmbH, Germany), with microwave power of 20.180 mW and a 300 W xenon lamp as the light source.

[0050] Depend on Figure 6 As can be seen from ab, under neutral conditions, no obvious EPR signal was observed in the supramolecular material without light; after illumination, the characteristic signal of HOO· appeared, while O2… - The characteristic signal of HOO· radicals was detected, and the intensity of the HOO· radical signal increased with the extension of illumination time. HOO· radicals were also detected in supramolecular materials constructed under alkaline conditions after illumination; at the same illumination time (11 min), the signal intensity was 13.8 times that under neutral conditions. Figure 6 As shown by CD, under neutral conditions, a weak ·OH characteristic signal can be observed in supramolecular materials even without light. After illumination, the signal intensity increases sharply and continues to accumulate over time. Under alkaline conditions, the ·OH signal initially increases and then decreases after illumination. ·O2 - It forms a conjugate acid-base pair with HOO·, with pKa ≈ 4.8. Theoretically, an alkaline environment is more favorable for O2. - It exists stably. However, the carboxyl groups (-COOH) on the supramolecular surface of HPPDI neutralize with bases: -COOH + OH- - à COO - + H2O. This reaction causes the catalyst-water interface to continuously consume OH-. - The spontaneous formation of localized acidic microregions promotes the generation of O2 in the first step of photocatalytic ORR. - Rapid protonation occurs, resulting in a stable HOO· form. Compared to neutral conditions, HPPDI supramolecular assemblies constructed under alkaline conditions exhibit more ordered molecular arrangement and higher charge separation efficiency, which is more conducive to electron transfer to the supramolecular surface for reaction with oxygen to generate ·O2. - This is consistent with the results of the spectrum and cyclic photocurrent response. Through a Hber-Weiss-like cycle (·O2) - +H₂O₂→O₂+OH - +·OH), where ·OH and ·O2 - They are also conjugate acid-base pairs, with pKa ≈ 11.9. Therefore, although HPPDI constructed under alkaline conditions produces O2... -While the efficiency is higher, the ·OH signal attenuates after a certain period of illumination due to the difficulty in maintaining stability under these conditions. These results indicate that amphiphilic HPPDI supramolecular materials with ordered arrangements can efficiently produce H2O2 via the ORR pathway, utilizing their high charge separation efficiency and unique interfacial microenvironment.

[0051] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. An amphiphilic supramolecular photocatalyst, characterized in that: The photocatalyst is formed by pH-controlled self-assembly of a hydrophilic peptide-modified perylene diimide derivative, HPPDI, and possesses a long-range ordered supramolecular structure; the structural formula of HPPDI is: ； The photocatalyst is uniformly dispersed in the aqueous phase and can catalyze the reduction of oxygen to hydrogen peroxide under visible light irradiation.

2. The amphiphilic supramolecular photocatalyst according to claim 1, characterized in that: The long-range order of the HPPDI supramolecular structure was regulated by adjusting the pH value of the system, and the resulting photocatalyst exhibited different assembly morphologies and photocatalytic activities under different pH conditions.

3. A method for preparing an amphiphilic supramolecular photocatalyst as described in claim 1 or 2, characterized in that, Includes the following steps: S1, HPPDI solid is dissolved in chloroform containing trifluoroacetic acid, and then sonicated to obtain a clear solution A; the chloroform solution of trifluoroacetic acid dissociates the HPPDI assembly into unimolecular solutions; S2, take solution A into a sample bottle, remove the solvent and dry it. After drying, the solid is obtained as HPPDI solid with an assembly structure that eliminates the initial metastable state and has a very low degree of molecular stacking. S3, the solid obtained in S2 is dissolved and assembled with sodium hydroxide aqueous solution, and HPPDI assembly solution B is obtained by temperature control stirring and slow cooling; S4. Solution B is diluted with an aqueous medium to adjust the pH value, then sonicated and allowed to stand to obtain HPPDI supramolecular dispersion C.

4. The method for preparing the amphiphilic supramolecular assembled photocatalyst according to claim 3, characterized in that: Glucose lactone (GDL) solid, used for in-situ pH regulation, was added to supramolecular dispersion C to obtain supramolecular dispersion D; the GDL concentration in the solution was 1.4-20 mM.

5. The method for preparing the amphiphilic supramolecular assembled photocatalyst according to claim 3, characterized in that: In step S3, the concentration of sodium hydroxide aqueous solution is 10-40 mM; the concentration of HPPDI is 1-5 mM. After dispersion, the solution is first sonicated at 50-60℃ for 20-40 min, then stirred at 350-600 rpm at 60℃ for more than 12 h, and then slowly cooled to room temperature at a rate of 5℃ every 30 min.

6. The method for preparing the amphiphilic supramolecular assembled photocatalyst according to claim 3, characterized in that: In step S4, the aqueous medium is pure water or BR buffer solution; when using buffer solution, its concentration is 2-10 mM, and its components are phosphoric acid, boric acid and acetic acid; the ultrasonic time is 5-10 min, and the standing time is 12-24 h.

7. The method for preparing the amphiphilic supramolecular assembled photocatalyst according to claim 3, characterized in that: In step S1, the volume fraction of trifluoroacetic acid in chloroform is 0.2-0.5 vol%; the ultrasonic time is 10-30 min and the frequency is 37 kHz; the concentration of HPPDI in solution A is 10-20 mM; in step S2, the solvent is removed by nitrogen purging, the vacuum drying temperature is 35-65℃, and the drying time is 48-72 h.

8. The use of an amphiphilic supramolecular photocatalyst prepared according to claim 3 or claim 4, characterized in that, For photocatalytic production of hydrogen peroxide, the following steps are included: (1) Under light-protected conditions, oxygen is continuously introduced into supramolecular dispersion C or supramolecular dispersion D and stirred. (2) Photocatalytic reaction is carried out by irradiating supramolecular dispersion C or supramolecular dispersion D with visible light while introducing oxygen and stirring. (3) Mix the reaction solution obtained in step (2) with potassium titanium oxalate / sulfuric acid solution to develop color, filter, and take the filtrate to obtain hydrogen peroxide color solution.

9. The use of the amphiphilic supramolecular assembly photocatalyst according to claim 8, characterized in that: In step (1), the concentration of HPPDI supramolecular dispersion is 0.25-2 mM; the stirring speed is 350-800 rpm; the oxygen bubbling time is 20-40 min; in step (2), the visible light is provided by a xenon lamp with a wavelength range of 380-800 nm, a light intensity of 100-325 mW / cm², and an irradiation time of 1-3 h; in step (3), the filter membrane used for filtration is one of MCE, nylon membrane or hydrophilic polyvinylidene fluoride membrane, with a membrane pore size of 0.22-0.45 μm.

10. The use of the amphiphilic supramolecular assembly photocatalyst according to claim 8, characterized in that: In step (3), the concentration of potassium titanium oxalate in the potassium titanium oxalate / sulfuric acid solution is 0.005-0.010 mol / L; the concentration of sulfuric acid is 1-5 mol / L; and the mixing ratio of the reaction solution to the potassium titanium oxalate / sulfuric acid solution is 1:(0.67-0.34).

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