Preparation method of Cu (I)-MPM / TiO2 heterojunction light response marine antifouling agent

Abstract

The present application relates to the field of marine antifouling agent, in particular to a kind of Cu (I) MPM / TiO2 Heterojunction photoresponsive marine antifouling agent preparation method.The present application uses natural biological small molecule compound containing thiol group, carboxyl group and amino trifunctional group as multifunctional bridge, which is dispersed with TiO2 In solvent to obtain suspension test solution;Then Cu (II) MPM powder prepared is added to suspension test solution and reacts, using the thiol group of small molecule to reduce Cu (II) in situ to Cu (I) And form stable Cu-S coordination bond, while carboxyl group is chemically bonded to TiO2 Surface, amino auxiliary forms hydrogen bond network, simultaneously realize the stable anchoring of Cu (I) And the firm construction of Cu (I) MPM / TiO2 Heterojunction.The Cu (I) MPM / TiO2 Heterojunction photoresponsive marine antifouling agent prepared by the present application has the advantages of long-acting controllable release of copper ions, excellent wide-spectrum light response antibacterial performance, good marine environmental stability, low heavy metal load, etc., and has wide application prospect in the field of marine engineering equipment antifouling.

Description

Technical Field

[0001] This invention relates to the field of marine antifouling agents, and more specifically, to a method for preparing a Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent. Background Technology

[0002] Marine biofouling is a long-standing global problem plaguing marine engineering equipment. Applying antifouling coatings to ship surfaces is the simplest and most effective technical solution to marine biofouling. Among these, inorganic antifouling agents based on cuprous oxide (Cu2O) have become the mainstay of current commercial applications. Their antifouling mechanism mainly relies on the continuous release of copper ions and limited photoresponsive antibacterial effects. However, traditional Cu2O antifouling agents have several key drawbacks: firstly, the release of copper ions is difficult to control precisely, with an initial burst followed by a sharp decline in effectiveness, failing to meet long-term protection requirements; secondly, the high recombination rate of photogenerated carriers and low quantum efficiency result in limited and unstable photoresponsive antifouling efficiency; and thirdly, the high mass percentage of copper (>80%) poses potential heavy metal environmental risks and bioaccumulation hazards. Therefore, the development of a new antifouling material system that achieves controllable ion release, possesses efficient and broad-spectrum photoresponsive capabilities, and has better environmental compatibility is urgently needed.

[0003] Against this backdrop, the development of efficient, durable, and environmentally friendly novel antifouling systems has become a research hotspot. Among them, "photoresponsive" antifouling agents have attracted much attention due to their green and sustainable advantages. Titanium dioxide (TiO2), as a classic photoresponsive material, has advantages such as good stability, non-toxicity, and low cost. However, its wide band gap (~3.2 eV) means it can only respond to ultraviolet light, resulting in severely insufficient solar energy utilization. Furthermore, photogenerated carriers recombine easily, limiting photoresponse efficiency. Constructing semiconductor heterojunctions is one of the most effective strategies to improve the photoresponse performance of TiO2. The key lies in selecting heterojunction partners with band structure matching and tight interfacial bonding for TiO2 to promote the spatial separation of photogenerated carriers. Molecular porous materials (MPMs) are ideal candidates for constructing heterojunctions with TiO2 due to their tunable structure, designable band structure, and excellent water stability. Through band structure matching, MPMs can form an effective built-in electric field with TiO2 to drive carrier separation; and the abundant hydrogen bonding sites on the MPM surface facilitate the formation of a tight and efficient heterojunction interface with TiO2. However, the aforementioned typical MPM materials all use Cu(II) as the metal node. Compared to Cu(II), Cu(I) has higher intrinsic toxicity to microorganisms and is a more ideal antifouling active center. However, Cu(I) is easily oxidized in air and disproportionates easily in solution, making it difficult to exist stably. How to stably introduce and anchor it in the porous framework is a major challenge in material design.

[0004] Existing patent CN109244243A discloses a method for modifying the electron transport layer of TiO2 with L-cysteine, applicable to the field of perovskite solar cells. This research confirms that the L-cysteine ​​molecule simultaneously contains three functional groups: thiol, carboxyl, and amino. Its carboxyl group can form chemical bonds with the TiO2 surface, and its thiol group can form stable coordination bonds with other materials, thereby significantly enhancing interfacial bonding, promoting charge transport, and inhibiting interfacial charge recombination. However, this technical solution does not involve copper-based antifouling active ingredients, nor does it solve core issues in marine antifouling such as Cu(I) stability and controllable release of copper ions, and is completely unrelated to the field of marine antifouling. Existing patent CN114150321A discloses a Z-type CuInS2 / TiO2 heterostructure nanocomposite photoanode material and its preparation method. This method first prepares TiO2 nanotubes, then treats them by soaking in a cysteine ​​solution, and then uses a hydrothermal method to grow CuInS2 quantum dots in situ on the TiO2 nanotubes to form a Z-type heterojunction for photogenerated cathode protection of metals. Although this technology involves cysteine ​​soaking of TiO2 and the construction of copper-containing heterostructures, cysteine ​​is only used as a pretreatment agent to improve the surface properties of TiO2. It does not utilize the reducing function of its thiol group to reduce Cu(II) to Cu(I) or form a Cu(I)-MPM framework. Moreover, its application field is metal corrosion protection rather than marine antifouling.

[0005] In summary, although attempts have been made in this field to utilize biomolecules containing specific functional groups as interface modifiers or structural ligands, their applications are often limited to single functions or specific fields, making it difficult to simultaneously solve the two problems of "stabilization of Cu(I)" and "construction of robust MPM / TiO2 heterojunctions". Summary of the Invention

[0006] In view of this, the present invention aims to propose a method for preparing Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent, so as to solve the problems of uncontrollable ion release, low photoresponse efficiency, weak heterojunction interface bonding and poor long-term service stability in existing antifouling materials.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] This invention discloses a method for preparing a Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent, comprising the following steps:

[0009] Step S1: Disperse a natural biomolecule containing trifunctional groups of thiol, carboxyl and amino groups with TiO2 in a solvent to obtain suspension A;

[0010] Step S2: Prepare Cu(II)-MPM powder;

[0011] Step S3: Add the Cu(II)-MPM powder obtained in step S2 to the suspension A obtained in step S1, and react under an inert atmosphere to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent.

[0012] In step S3, the synergistic effect of thiol, carboxyl and amino groups in natural biological small molecule compounds is utilized to simultaneously achieve the in-situ reduction and stabilization of Cu(II) and the construction of the Cu(I)-MPM and TiO2 heterojunction interface.

[0013] The thiol groups of natural biomolecules can reduce Cu(II) in situ to Cu(I) and form Cu-S coordination bonds, firmly anchoring Cu(I) within the MPM framework. Simultaneously, their carboxyl groups can form chemical bonds with the TiO2 surface, constructing a heterojunction interface between Cu(I)-MPM and TiO2. Furthermore, their amino groups can form hydrogen bonds with the TiO2 surface and participate in the construction of the hydrogen bond network within the MPM framework, enhancing the robustness of the Cu(I)-MPM / TiO2 heterojunction interface. Through the synergistic effect of the three functional groups in the natural biomolecules, this invention simultaneously achieves the in-situ reduction of Cu(II), the stable anchoring of Cu(I), and the construction of a robust heterostructure between Cu(I)-MPM and TiO2 in the same reaction system, fundamentally solving the problems of easy oxidation and disproportionation of Cu(I) and weak bonding at the heterojunction interface.

[0014] Furthermore, the natural biological small molecule compound is one or more of L-cysteine, glutathione, L-homocysteine, and γ-glutamic acid-cysteine.

[0015] These biomolecules are all naturally occurring, widely sourced, and biodegradable amino acids or their derivatives, conforming to the principles of green chemistry and sustainable development. Furthermore, their molecular structures simultaneously possess the three functional groups required by this invention, providing a preferred and reliable material basis for implementing the "bridge" function of this invention, ensuring the feasibility and environmental friendliness of the preparation method. In addition, although different natural biomolecules differ in their side-chain structures, they can all achieve in-situ reduction of Cu(II), stable anchoring of Cu(I), and robust construction of heterojunction interfaces through the synergistic effect of their shared thiol, carboxyl, and amino functional groups, fully demonstrating the universality and flexibility of the technical solution of this invention.

[0016] Furthermore, in step S1, the molar ratio of the natural biomolecule compound to TiO2 is 1:(0.5~5).

[0017] This molar ratio range ensures that the TiO2 surface is fully modified by biomolecules, providing sufficient active sites for the subsequent binding of Cu(I)-MPM. Too low a ratio will result in insufficient modification of the TiO2 surface, affecting the strength of the subsequent heterostructure construction. Too high a ratio may cause waste of small molecules or self-aggregation, which is not conducive to interface formation.

[0018] Furthermore, in step S3, the mass concentration of Cu(II)-MPM powder in suspension A is 0.1~10 g / L, and the mass ratio of Cu(II)-MPM powder to TiO2 in suspension A is 1:(0.1~10).

[0019] The appropriate mass concentration ensures good dispersion and effective mass transfer of Cu(II)-MPM in the reaction system, which is beneficial to uniform reaction. The feed mass ratio directly determines the relative content of photocatalytic component TiO2 and antibacterial slow-release component Cu(I)-MPM in the final heterojunction. It is the key to obtaining the best bandgap matching, photogenerated carrier separation efficiency and antifouling performance synergy, and avoids performance shortcomings caused by excessive or insufficient amount of a certain component.

[0020] Furthermore, in step S2, the raw materials for preparing Cu(II)-MPM powder include Cu(II) copper source, adenine and ammonium hexafluorosilicate, and the molar ratio of Cu(II) copper source, adenine and ammonium hexafluorosilicate is 1:(0.5~5):(0.5~5).

[0021] Adenine, as a nitrogen-containing organic ligand, coordinates with Cu(II) ions to construct the main structure of the Cu(II)-MPM porous framework, which directly determines the intrinsic band structure of the Cu(II)-MPM material. Ammonium hexafluorosilicate acts as a structure directing agent and counter anion, its participation contributing to the formation and stabilization of the Cu(II)-MPM porous framework, while filling the pores and endowing it with excellent water stability. This combination and ratio of raw materials can successfully synthesize Cu(II)-MPM powder with a specific porous structure, excellent water stability, and suitable band structure.

[0022] Furthermore, the Cu(II) copper source is one or more of copper nitrate, cuprous chloride, cuprous bromide, cuprous iodide, and cuprous acetate.

[0023] The copper sources mentioned above are all common soluble copper salts, which are inexpensive and readily available. They can provide stable Cu(II) ions in the reaction system, reacting with adenine and ammonium hexafluorosilicate to generate high-quality Cu(II)-MPM powder, ensuring the purity and reproducibility of Cu(II)-MPM precursor synthesis. The anions of different copper sources have little impact on the structure and properties of MPM, and can be flexibly selected according to actual production conditions.

[0024] Furthermore, in step S2, when Cu(II)-MPM powder is prepared using Cu(II) copper source, adenine and ammonium hexafluorosilicate, the reaction temperature is 20~80℃ and the reaction time is 2~24h.

[0025] The reaction conditions are mild, which can ensure that the reaction proceeds fully while avoiding the decomposition of adenine and the collapse of the Cu(II)-MPM framework structure caused by high temperature. By controlling the reaction temperature and time, the grain size and morphology of Cu(II)-MPM can be precisely controlled, thereby adjusting its specific surface area and pore structure, and optimizing the subsequent reduction reaction and heterojunction composite effect.

[0026] Furthermore, in step S3, the reaction temperature of Cu(II)-MPM powder with suspension A is 20~60℃, and the reaction time is 1~12h.

[0027] The mild reaction conditions ensure that the thiol groups of natural biomolecules can smoothly reduce Cu(II) to Cu(I), while effectively preventing the generated Cu(I) from being oxidized or disproportionated; they also avoid the decomposition of biomolecules and the destruction of the heterojunction interface caused by high temperature, ensuring the formation of a robust and efficient Cu(I)-MPM / TiO2 heterojunction structure; the shorter reaction time also helps to improve production efficiency and reduce production costs.

[0028] Furthermore, TiO2 can be one or more of the following: anatase TiO2, rutile TiO2, TiO2 nanotubes, and TiO2 nanosheets.

[0029] The aforementioned TiO2 materials all exhibit excellent photoresponse performance and chemical stability, making them commonly used photocatalytic materials in this field. Different morphologies of TiO2 possess their own unique structural advantages: anatase TiO2 exhibits high photocatalytic activity, rutile TiO2 demonstrates good stability, and TiO2 nanotubes and TiO2 nanosheets possess larger specific surface areas and shorter carrier transport paths. By selecting different TiO2 materials, the photoresponse performance and structural stability of antifouling agents can be further optimized.

[0030] The present invention also discloses a Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent, which is prepared by the above preparation method.

[0031] The Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent prepared in this invention has Cu(I) stably anchored, and the heterojunction interface is firmly bonded by chemical bonds and hydrogen bond networks, thus achieving long-term and controllable release of copper ions, avoiding the defects of initial explosive release and later failure of traditional Cu2O antifouling agents; at the same time, it significantly promotes the spatial separation and transport of photogenerated charge carriers, endowing the material with efficient and wide-spectrum photoresponsive antibacterial properties; and it also has excellent marine environmental stability and low heavy metal load, which can meet the long-term antifouling requirements of marine engineering equipment.

[0032] Compared with existing technologies, the preparation method of the Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent described in this invention has the following advantages:

[0033] (1) Solving the problem of Cu(I) stability and achieving long-term controllable release of copper ions: This invention uses a natural bio-small molecule compound containing three functional groups and utilizes the thiol group (-SH) in it to reduce Cu(II) in Cu(II)-MPM to Cu(I) in situ. At the same time, by forming a stable Cu-S coordination bond or a disulfide bond that it may form, Cu(I) is stably anchored within the MPM framework, which fundamentally solves the problem of Cu(I) being easily oxidized and deactivated and easily disproportionated. This achieves long-term and stable release of copper ions in the seawater environment and avoids the defects of traditional Cu2O antifouling agents, such as initial "explosive release" and later failure.

[0034] (2) Constructing a stable heterojunction interface to significantly improve photocatalytic efficiency: This invention utilizes the chemical bonding between the carboxyl groups (-COOH) in the above-mentioned biomolecules and the hydroxyl groups on the surface of TiO2 to construct a tight and robust heterojunction interface between Cu(I)-MPM and TiO2. This interface not only facilitates the spatial separation and transport of photogenerated carriers, greatly improving quantum efficiency, but also expands the absorption range of visible light by the material through band matching, effectively overcoming the intrinsic defects of TiO2, such as a large band gap and easy recombination of photogenerated carriers.

[0035] (3) Synergistic enhancement of material stability for long-term marine service: This invention uses MPM, which has excellent water stability, as the framework, and combines it with the hydrogen bond network constructed by amino groups (-NH2) in small biological molecules to endow the composite material with excellent structural stability in seawater environment. At the same time, the multi-point anchoring interface formed between Cu(I)-MPM and TiO2 through chemical bonding and hydrogen bonding further strengthens the overall robustness of the heterostructure, ensuring that the material maintains high-efficiency antifouling activity under long-term immersion conditions.

[0036] (4) Environmentally friendly and low heavy metal load: This invention achieves high-efficiency antifouling performance by reducing Cu(II) to Cu(I) with higher antibacterial activity and combining the spatial confinement effect of the MPM framework, while significantly reducing the total amount of copper used. This reduces the environmental risks and bioaccumulation hazards of heavy metals associated with traditional copper-based antifouling agents. The natural biological small molecule compounds used are widely available and biodegradable, which is in line with the development concept of green chemistry and sustainable marine antifouling. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 This is a schematic diagram of the preparation process of Cu(I)-MPM / TiO2;

[0039] Figure 2 Figure a shows the transmission electron microscope (TEM) morphology of TiO2 in Example 1; Figure b shows the TEM morphology of Cu(II)-MPM in Example 1; Figure c shows the TEM morphology of Cu(I)-MPM obtained after L-cysteine ​​modification of Cu(II)-MPM in Example 1; Figure d shows the TEM morphology of Cu(I)-MPM / TiO2 heterojunction obtained in Example 1; Figure e shows the high-resolution TEM lattice fringe pattern of Cu(I)-MPM / TiO2 heterojunction in Figure d; Figure f shows the electron diffraction pattern of Cu(I)-MPM / TiO2 heterojunction in Figure d.

[0040] Figure 3 The upper spectrum is a comparison of the X-ray photoelectron spectra (Cu2p fine spectrum) of the Cu(I)-MPM / TiO2 heterojunction prepared by L-cysteine ​​modification in Example 1, and the lower spectrum is the Cu2p spectrum of Cu(II)-MPM in Example 1.

[0041] Figure 4 The upper spectrum is the Cu2p spectrum of the Cu(I)-MPM / TiO2 heterojunction prepared by glutathione modification in Example 2, and the lower spectrum is the Cu2p spectrum of Cu(II)-MPM in Example 2.

[0042] Figure 5 The upper spectrum is the Cu2p spectrum of the Cu(I)-MPM / TiO2 heterojunction prepared by L-homocysteine ​​modification in Example 3, and the lower spectrum is the Cu2p spectrum of Cu(II)-MPM in Example 3.

[0043] Figure 6The upper spectrum is the Cu2p spectrum of the Cu(I)-MPM / TiO2 heterojunction prepared by γ-glutamic acid-cysteine ​​modification in Example 4, and the lower spectrum is the Cu2p spectrum of Cu(II)-MPM in Example 4. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The preparation process of the Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent in this invention is as follows:

[0047] Step S1: Preparation of Suspension A

[0048] Natural biological small molecule compounds containing thiol, carboxyl, and amino groups in their molecular structure are dissolved in their respective solvents, and TiO2 nanomaterials are added and dispersed evenly to obtain suspension A.

[0049] Step S2: Preparation of Cu(II)-MPM powder

[0050] Cu(II) copper source, adenine, and ammonium hexafluorosilicate were dissolved in their respective solvents, mixed and reacted at a certain temperature for a period of time, and then separated, washed, and dried to obtain Cu(II)-MPM powder.

[0051] Step S3: Preparation of Cu(I)-MPM / TiO2 heterojunction

[0052] The Cu(II)-MPM powder obtained in step S2 was added to suspension A and mixed and reacted at a certain temperature for a period of time. After separation, washing and drying, Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent was obtained.

[0053] The solvents used in steps S1 and S2 are one or more of water, methanol, ethanol, and acetonitrile.

[0054] Material characterization and performance testing:

[0055] Microstructure and structural characterization: The microstructures of TiO2, Cu(II)-MPM, Cu(I)-MPM and Cu(I)-MPM / TiO2 heterojunctions were observed by TEM; the lattice structure of the interface of Cu(I)-MPM / TiO2 heterojunction was analyzed by high-resolution TEM; the crystallinity of Cu(I)-MPM / TiO2 heterojunction was characterized by selected area electron diffraction; and the valence state of copper in Cu(I)-MPM / TiO2 heterojunction and Cu(II)-MPM was analyzed by Cu2p fine spectrum in X-ray photoelectron spectroscopy.

[0056] Photoresponse performance testing: A three-electrode system was used. The working electrode was made by coating the prepared material onto conductive glass, the counter electrode was a platinum sheet, the reference electrode was a saturated calomel electrode, and the electrolyte was 0.1M Na2SO4 solution. Simulated sunlight (AM 1.5G, 100mW / cm²) was applied. 2 The photocurrent density of the test material under irradiation.

[0057] Antibacterial performance test: The plate count method was used to determine the antibacterial rate of Cu(I)-MPM / TiO2 heterojunctions using three typical marine fouling bacteria, namely Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, as test species.

[0058] It should be noted that the core of this invention lies in utilizing the synergistic effect of natural trifunctional biomolecules to simultaneously complete the in-situ reduction of Cu(II), the stable anchoring of Cu(I), and the robust construction of the Cu(I)-MPM-TiO2 heterojunction interface in a single reaction system. The reaction principle is as follows:

[0059] In-situ reduction and strong coordination of thiol groups: The thiol groups in natural biological small molecule compounds first act as mild reducing agents, reacting with Cu(II) ions in Cu(II)-MPM powder in a redox reaction, reducing them in-situ to Cu(I) with higher intrinsic antibacterial activity. Immediately afterwards, the reduced Cu(I) (soft acid) undergoes strong coordination with the thiol sulfur atoms (soft base) of the same or neighboring molecules, forming an exceptionally strong Cu-S coordination bond. This stably anchors the highly active but extremely unstable Cu(I) within the porous framework of MPM, forming Cu(I)-MPM, fundamentally solving the problem of Cu(I)'s easy oxidation and disproportionation.

[0060] The chemical bonding effect of carboxyl groups: Carboxyl groups in natural biomolecules can undergo esterification or bidentate coordination reactions with the abundant hydroxyl groups on the TiO2 surface to form Ti-OC covalent bonds, achieving strong chemical bonding between biomolecules and the TiO2 surface. This ensures that one end of the biomolecule is strongly fixed and will not easily fall off in subsequent reactions or the environment in which it is used, providing a stable foundation for the subsequent connection of the Cu(I)-MPM framework.

[0061] Hydrogen-bonding assisted role of amino groups: Amino groups in natural biomolecules can form intermolecular hydrogen bonds with hydroxyl groups on the TiO2 surface, producing a synergistic anchoring effect with carboxyl groups. This significantly enhances the adsorption strength of biomolecules on the TiO2 surface, preventing their detachment during subsequent reactions. On the other hand, they can form weak coordination with Cu(I), further improving the anchoring stability of Cu(I) within the MPM framework. Furthermore, amino groups can act as hydrogen bond donors, participating in the construction of the hydrogen bond network within the Cu(I)-MPM framework, further connecting Cu(I)-MPM and TiO2 into a unified whole. This improves the structural stability and erosion resistance of the Cu(I)-MPM / TiO2 heterojunction in seawater environments, ensuring the integrity of the heterojunction interface and the durability of antifouling activity during long-term service.

[0062] Specifically, after step S1, a layer of biomolecules is uniformly covered on the surface of TiO2. One end of the molecules is fixed to the TiO2 surface by carboxyl and amino groups, while the other end of the thiol group is exposed, providing an active site for the subsequent reaction with Cu(II)-MPM.

[0063] In step S2, adenine acts as a nitrogen-containing organic ligand, and the N7 and N9 atoms in its molecule can form coordination bonds with Cu(II) ions to construct the main framework of a two-dimensional layered structure. Hexafluorosilicate acts as a counter anion, filling the pores between layers through hydrogen bonding, thus supporting the Cu(II)-MPM framework structure and improving its water stability. Cu(II)-MPM powder is obtained after the reaction.

[0064] In step S3, the thiol and amino groups in the biomolecules pre-anchored on the TiO2 surface function simultaneously to complete the in-situ reduction of Cu(II) and the stable anchoring of Cu(I) under mild conditions, as well as the construction of the Cu(I)-MPM-TiO2 heterojunction interface. The specific process is as follows:

[0065] Exposed thiol groups come into contact with Cu(II) sites on the Cu(II)-MPM powder surface, undergoing a redox reaction to reduce them in situ to Cu(I). The newly generated Cu(I) immediately forms strong Cu-S coordination bonds with thiol sulfur atoms on the same or adjacent biomolecules through "soft acid-soft base" interactions, thus stably confining and anchoring the highly active Cu(I) to the porous framework nodes of the MPM. Furthermore, the amino groups of the biomolecules not only enhance their anchoring on the TiO2 surface through hydrogen bonds, but more importantly, they also form a broad hydrogen bond network with adenine ligands in the Cu(I)-MPM framework and with carboxyl or amino groups on adjacent biomolecules. This network acts like a "molecular scaffolding," spatially weaving the stabilized Cu(I)-MPM framework tightly together with the TiO2 surface, synergistically with the chemical bonding of carboxyl groups, ultimately constructing a Cu(I)-MPM / TiO2 heterojunction interface that is stably bound together by multiple strong interactions of covalent bonds, coordination bonds, and hydrogen bonds.

[0066] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0067] Example 1

[0068] In this embodiment, L-cysteine ​​is used as a multifunctional bridging molecule to prepare Cu(I)-MPM / TiO2 heterojunction material. The chemical structural formula of L-cysteine ​​is shown in formula (I), and the specific steps are as follows:

[0069]

[0070] Equation (I)

[0071] Step S1: Preparation of Suspension A

[0072] 0.01 mol of L-cysteine ​​was dissolved in 50 mL of deionized water, and 0.5 g of anatase TiO2 nanoparticles were added. The mixture was ultrasonically dispersed for 30 min to obtain suspension A.

[0073] Step S2: Preparation of Cu(II)-MPM powder

[0074] 0.01 mol of cuprous nitrate trihydrate (used as a Cu(II) copper source, partially oxidized to Cu(II) under the reaction conditions), 0.015 mol of adenine, and 0.02 mol of ammonium hexafluorosilicate were dissolved in 100 mL of deionized water, and the mixture was stirred in a water bath at 60 °C for 12 h. After the reaction was completed, the mixture was centrifuged, washed three times alternately with deionized water and ethanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(II)-MPM powder.

[0075] Step S3: Preparation of Cu(I)-MPM / TiO2 heterojunction

[0076] 0.2 g of Cu(II)-MPM powder obtained in step S2 was added to suspension A obtained in step S1, and the mixture was stirred at 40 °C for 6 h under nitrogen protection. After the reaction was completed, the mixture was centrifuged, washed three times alternately with deionized water and ethanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent.

[0077] Material characterization and performance testing:

[0078] Microscopic morphology and structural characterization: TEM characterization results are as follows Figure 2 As shown: Figure a is the TEM morphology of pure TiO2, which shows that TiO2 is a uniform particle with a particle size of 10~20nm; Figure b is the TEM morphology of Cu(II)-MPM, which shows that it is a uniform two-dimensional lamellar structure with a particle size of about 1~2μm; Figure c is the TEM morphology of Cu(I)-MPM obtained after L-cysteine ​​modification, which shows that it basically maintains the original two-dimensional lamellar structure without obvious structural collapse; Figure d is the TEM morphology of the finally obtained Cu(I)-MPM / TiO2 heterojunction, which shows that TiO2 particles are uniformly coated on the surface of Cu(I)-MPM lamellars, indicating that the two are successfully composited.

[0079] High-resolution TEM and electron diffraction characterization results are as follows Figure 2 As shown in e and f: lattice fringes with a spacing of 0.352 nm can be clearly observed at the interface of the heterojunction, corresponding to the (101) crystal plane of anatase TiO2; the electron diffraction pattern shows clear polycrystalline diffraction rings, indicating that the composite Cu(I)-MPM / TiO2 heterojunction has good crystallinity.

[0080] The Cu2p fine spectrum characterization results of Cu(II)-MPM and Cu(I)-MPM / TiO2 heterostructures are as follows: Figure 3 As shown, Cu(II)-MPM has a distinct satellite peak at a binding energy of approximately 940-945 eV, which is a characteristic signal of Cu(II); while the satellite peak of Cu(I)-MPM / TiO2 heterojunction basically disappears in this region, indicating that the thiol group of L-cysteine ​​successfully reduces Cu(II) to Cu(I) in situ, that is, the copper element in L-cysteine-modified Cu(I)-MPM / TiO2 is positive monovalent.

[0081] Photoresponse performance tests show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has a photocurrent density of 2.38 μA / cm². 2 It is approximately 4.2 times that of pure TiO2.

[0082] The antibacterial performance test results show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has an inhibition rate of 99.6% against Escherichia coli, 99.2% against Staphylococcus aureus, and 99.8% against Pseudomonas aeruginosa.

[0083] In this embodiment, the thiol group of L-cysteine ​​reduces Cu(II) in Cu(II)-MPM to Cu(I), while it is oxidized to cystine and participates in coordination to form a stable Cu(I)-S bond; the carboxyl group chemically bonds with the hydroxyl group on the TiO2 surface, and the amino group participates in the construction of the hydrogen bond network, jointly constructing a stable heterojunction interface.

[0084] Example 2

[0085] In this embodiment, reduced glutathione is used as a multifunctional bridging molecule to prepare Cu(I)-MPM / TiO2 heterojunction material. The chemical structural formula of reduced glutathione is shown in formula (II), and the specific preparation steps are as follows:

[0086]

[0087] Equation (II)

[0088] Step S1: Preparation of Suspension A

[0089] 0.01 mol of glutathione was dissolved in 50 mL of a 1:1 ethanol / water mixture, and 0.8 g of anatase TiO2 nanoparticles were added. The mixture was ultrasonically dispersed for 30 min to obtain suspension A.

[0090] Step S2: Preparation of Cu(II)-MPM powder

[0091] 0.01 mol cuprous chloride (used as a Cu(II) copper source, partially oxidized to Cu(II) under the reaction conditions), 0.02 mol adenine, and 0.02 mol ammonium hexafluorosilicate were dissolved in 100 mL of ethanol, and the mixture was stirred in a water bath at 50 °C for 10 h. After the reaction was completed, the mixture was centrifuged, washed three times with ethanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(II)-MPM powder.

[0092] Step S3: Preparation of Cu(I)-MPM / TiO2 heterojunction

[0093] 0.3 g of Cu(II)-MPM powder obtained in step S2 was added to suspension A obtained in step S1, and the mixture was stirred and reacted at 35 °C for 8 h under nitrogen protection. After the reaction was completed, the mixture was centrifuged, washed three times with ethanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent.

[0094] Material characterization and performance testing:

[0095] The Cu2p fine spectrum characterization results of Cu(II)-MPM and Cu(I)-MPM / TiO2 heterojunctions in this embodiment are as follows: Figure 4 As shown, Cu(II)-MPM has a distinct satellite peak at a binding energy of approximately 940-945 eV, while the satellite peak of Cu(I)-MPM / TiO2 heterojunction basically disappears in this region. This indicates that the thiol group of glutathione successfully reduces Cu(II) to Cu(I) in situ, meaning that the copper element in glutathione-modified Cu(I)-MPM / TiO2 is in the +1 valence.

[0096] Photoresponse performance tests show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has a photocurrent density of 2.51 μA / cm². 2 It is approximately 4.4 times that of pure TiO2.

[0097] The antibacterial performance test results show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has an antibacterial rate of 95.7% against Escherichia coli, 99.4% against Staphylococcus aureus, and 99.9% against Pseudomonas aeruginosa.

[0098] In this embodiment, the cysteine ​​residues in the reduced glutathione provide thiol groups, reducing Cu(II) to Cu(I) and forming a stable coordination; the carboxyl groups of the glutamic acid residues and glycine residues synergistically enhance the anchoring effect with TiO2; and the amino groups participate in the construction of the hydrogen bond network in the MPM framework.

[0099] Example 3

[0100] In this embodiment, L-homocysteine ​​is used as a multifunctional bridging molecule to prepare Cu(I)-MPM / TiO2 heterojunction material. The chemical structural formula of L-homocysteine ​​is shown in formula (Ⅲ), and the specific steps are as follows:

[0101]

[0102] Formula (III)

[0103] Step S1: Preparation of Suspension A

[0104] 0.015 mol of L-homocysteine ​​was dissolved in 50 mL of methanol, and 0.6 g of anatase TiO2 nanoparticles were added. The mixture was ultrasonically dispersed for 30 min to obtain suspension A.

[0105] Step S2: Preparation of Cu(II)-MPM powder

[0106] 0.01 mol cuprous bromide (used as a Cu(II) copper source, partially oxidized to Cu(II) under the reaction conditions), 0.01 mol adenine, and 0.01 mol ammonium hexafluorosilicate were dissolved in 100 mL of methanol, and the mixture was stirred in a water bath at 55 °C for 8 h. After the reaction was completed, the mixture was centrifuged, washed three times with methanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(II)-MPM powder.

[0107] Step S3: Preparation of Cu(I)-MPM / TiO2 heterojunction

[0108] 0.25 g of Cu(II)-MPM powder obtained in step S2 was added to suspension A obtained in step S1, and the mixture was stirred and reacted at 45 °C for 5 h under nitrogen protection. After the reaction was completed, the mixture was centrifuged, washed three times with methanol, and dried under vacuum at 60 °C for 12 h to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent.

[0109] Material characterization and performance testing:

[0110] The Cu2p fine spectrum characterization results of Cu(II)-MPM and Cu(I)-MPM / TiO2 heterojunctions in this embodiment are as follows: Figure 5 As shown, Cu(II)-MPM has a distinct satellite peak at a binding energy of approximately 940-945 eV, while the satellite peak of Cu(I)-MPM / TiO2 heterojunction basically disappears in this region. This indicates that the thiol group of L-homocysteine ​​successfully reduces Cu(II) to Cu(I) in situ, meaning that the copper element in L-homocysteine-modified Cu(I)-MPM / TiO2 has a positive monovalent.

[0111] Photoresponse performance tests show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has a photocurrent density of 2.62 μA / cm². 2 It is approximately 4.6 times that of pure TiO2.

[0112] The antibacterial performance test results show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has an antibacterial rate of 96.8% against Escherichia coli, 99.5% against Staphylococcus aureus, and 99.9% against Pseudomonas aeruginosa.

[0113] In this embodiment, the thiol group of L-homocysteine ​​forms a strong coordination bond with Cu(I), and at the same time reduces Cu(II) that may exist in the system to Cu(I); its carboxyl group forms a chemical bond with the hydroxyl group on the surface of the anatase phase TiO2; since the side chain has one more methylene group than L-cysteine, the molecular flexibility is enhanced, which is beneficial to interface adaptation.

[0114] Example 4

[0115] In this embodiment, γ-glutamic acid-cysteine ​​is used as a multifunctional bridging molecule to prepare Cu(I)-MPM / TiO2 heterojunction material. The chemical structural formula of γ-glutamic acid-cysteine ​​is shown in formula (Ⅳ), and the specific steps are as follows:

[0116]

[0117] Equation (Ⅳ)

[0118] Step S1: Preparation of Suspension A

[0119] 0.012 mol of γ-glutamic acid-cysteine ​​was dissolved in 50 mL of a 1:1 acetonitrile / water mixture, and 0.4 g of rutile TiO2 nanoparticles were added. The mixture was ultrasonically dispersed for 30 min to obtain suspension A.

[0120] Step S2: Preparation of Cu(II)-MPM powder

[0121] 0.01 mol cuprous acetate (used as a Cu(II) copper source, partially oxidized to Cu(II) under the reaction conditions), 0.012 mol adenine, and 0.01 mol ammonium hexafluorosilicate were dissolved in 100 mL acetonitrile, and the mixture was stirred in a water bath at 65 °C for 15 h. After the reaction was completed, the mixture was centrifuged, washed three times with acetonitrile, and dried under vacuum at 60 °C for 12 h to obtain Cu(II)-MPM powder.

[0122] Step S3: Preparation of Cu(I)-MPM / TiO2 heterojunction

[0123] 0.15 g of Cu(II)-MPM powder obtained in step S2 was added to suspension A obtained in step S1, and the mixture was stirred and reacted at 30 °C for 10 h under nitrogen protection. After the reaction was completed, the mixture was centrifuged, washed three times with acetonitrile, and dried under vacuum at 60 °C for 12 h to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent.

[0124] Material characterization and performance testing:

[0125] The Cu2p fine spectrum characterization results of Cu(II)-MPM and Cu(I)-MPM / TiO2 heterojunctions in this embodiment are as follows: Figure 6 As shown, Cu(II)-MPM has a distinct satellite peak at a binding energy of approximately 940-945 eV, while the satellite peak of Cu(I)-MPM / TiO2 heterojunction basically disappears in this region. This indicates that the thiol group of γ-glutamic acid-cysteine ​​successfully reduces Cu(II) to Cu(I) in situ, meaning that the copper element in γ-glutamic acid-cysteine ​​modified Cu(I)-MPM / TiO2 is in the +1 valence.

[0126] Photoresponse performance testing shows that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has a photocurrent density of 2.45 μA / cm². 2 It is approximately 4.3 times that of pure TiO2.

[0127] The antibacterial performance test results show that the Cu(I)-MPM / TiO2 heterojunction material prepared in this embodiment has an antibacterial rate of 99.7% against Escherichia coli, 97.4% against Staphylococcus aureus, and 98.8% against Pseudomonas aeruginosa.

[0128] In this embodiment, γ-glutamic acid-cysteine ​​retains free thiol groups, forming stable Cu-S bonds with Cu(I), effectively preventing Cu(I) oxidation; the carboxyl groups are chemically bonded to the TiO2 surface, and the α-carboxyl groups of glutamic acid residues and cysteine ​​residues in the molecule can simultaneously form covalent bonds with the hydroxyl groups on the TiO2 surface, which significantly enhances the interfacial anchoring strength compared to single carboxyl biomolecules.

[0129] In summary, this invention provides a method for preparing a Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent. This method utilizes a natural biomolecule containing thiol, carboxyl, and amino groups as a multifunctional bridge. The thiol group is used to reduce Cu(II) in situ to Cu(I) and form a stable Cu-S coordination bond. Simultaneously, the carboxyl group chemically bonds with the TiO2 surface, and the amino group assists in forming a hydrogen bond network, thus simultaneously achieving stable anchoring of Cu(I) and robust construction of the Cu(I)-MPM / TiO2 heterojunction. The resulting Cu(I)-MPM / TiO2 heterojunction photoresponsive antifouling agent possesses advantages such as long-term controllable release of copper ions, excellent broadband photoresponsive antibacterial properties, good stability in the marine environment, and low heavy metal load, showing broad application prospects in the field of antifouling for marine engineering equipment.

[0130] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent, characterized in that, Includes the following steps: Step S1: Disperse a natural biomolecule compound containing three functional groups (thiol, carboxyl, and amino) with TiO2 in a solvent to obtain suspension A; Step S2: Prepare Cu(II)-MPM powder; Step S3: Add the Cu(II)-MPM powder obtained in step S2 to the suspension A obtained in step S1, and react under an inert atmosphere to obtain Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent. In step S3, the synergistic effect of thiol, carboxyl and amino groups in natural biological small molecule compounds is utilized to simultaneously achieve the in-situ reduction and stabilization of Cu(II) and the construction of the Cu(I)-MPM and TiO2 heterojunction interface.

2. The preparation method according to claim 1, characterized in that, The natural biological small molecule compound is one or more of L-cysteine, glutathione, L-homocysteine, and γ-glutamic acid-cysteine.

3. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of the natural biomolecule compound to TiO2 is 1:(0.5~5).

4. The preparation method according to claim 1, characterized in that, In step S3, the mass concentration of Cu(II)-MPM powder in suspension A is 0.1~10 g / L; and the mass ratio of Cu(II)-MPM powder to TiO2 in suspension A is 1:(0.1~10).

5. The preparation method according to claim 1, characterized in that, In step S2, the raw materials for preparing Cu(II)-MPM powder include Cu(II) copper source, adenine and ammonium hexafluorosilicate, and the molar ratio of Cu(II) copper source, adenine and ammonium hexafluorosilicate is 1:(0.5~5):(0.5~5).

6. The preparation method according to claim 5, characterized in that, The Cu(II) copper source is one or more of copper nitrate, cuprous chloride, cuprous bromide, cuprous iodide, and cuprous acetate.

7. The preparation method according to claim 5, characterized in that, In step S2, when the Cu(II) copper source, adenine and ammonium hexafluorosilicate are used to prepare the Cu(II)-MPM powder, the reaction temperature is 20~80℃ and the reaction time is 2~24h.

8. The preparation method according to claim 1, characterized in that, In step S3, the reaction temperature of the Cu(II)-MPM powder with the suspension A is 20~60℃, and the reaction time is 1~12h.

9. The preparation method according to claim 1, characterized in that, The TiO2 is one or more of the following: anatase TiO2, rutile TiO2, TiO2 nanotubes, and TiO2 nanosheets.

10. A Cu(I)-MPM / TiO2 heterojunction photoresponsive marine antifouling agent, characterized in that, The antifouling agent is prepared by the preparation method according to any one of claims 1 to 9.

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