A method for synthesizing a two-dimensional conjugated coordination polymer film based on ammonia-assisted chemical vapor deposition
Patent Information
- Application Number
- CN202510365061.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2026-09-29
AI Technical Summary
与传统方法相比，本发明不仅有效解决了残余质子阻碍有序配位网络组装的问题，还避免了溶液法中颗粒污染、溶液诱导腐蚀和表面张力效应等不利因素，同时具备可大面积制备的可行性以及对薄膜生长的高控制性，能够与现有微制造技术无缝兼容，是2D c-CP薄膜制备方式的创新，具有重要的技术价值
[0046]1.本发明通过NH3辅助化学气相沉积(CVD)方法制备二维共轭配位聚合物薄膜，不需要苛刻的反应条件及繁琐的操作步骤，即可实现高效、便捷地制备高质量的2D c-CP薄膜，所述方法显著简化了制备过程，降低了制备难度。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials chemistry technology, specifically relating to a method for synthesizing two-dimensional conjugated coordination polymer films based on ammonia-assisted chemical vapor deposition. Background Technology
[0002] As electronic devices evolve towards higher performance, higher integration, and miniaturization, higher demands are placed on the electrical and mechanical properties of materials. Electrically conductive coordination polymers (ECCPs) and metal-organic frameworks (MOFs), as emerging materials, have attracted widespread attention in optoelectronics and spintronics. Two-dimensional (2D) conjugated coordination polymers (c-CPs), due to their in-plane extended π-conjugation and perpendicular π-π interactions, exhibit many unique properties, including high electrical conductivity, superconductivity, photosensitivity, and inherent ferromagnetism. These characteristics make 2D c-CPs one of the most promising materials.
[0003] Currently, large-scale production of 2D c-CP nanosheets can be achieved by reassembling the exfoliated nanosheets, but this method still suffers from poor control over crystallinity and thickness. Therefore, most 2D c-CP films are synthesized using liquid-liquid or gas-liquid interfaces. While these methods offer advantages in large-scale production and thickness control, they often suffer from particle contamination due to uniform crystal nucleation in solution, and external charge scattering, which affects charge transport properties and limits device performance. Furthermore, solution-induced corrosion and surface tension effects also hinder the integration of the synthesized materials into nanodevices.
[0004] To overcome these problems, chemical vapor deposition (CVD), as a solvent-free synthesis method, has gradually attracted attention. CVD can form uniform films, avoid surface residues, and produce smooth surfaces, which holds promise for synthesizing more high-performance film materials, driving technological progress and industrial upgrading in related fields. Although some studies have successfully used CVD to study two-dimensional conjugated coordination polymers, effective solutions are still lacking for synthesizing highly crystalline products, especially for optimizing film quality through transfer-free strategies. Summary of the Invention
[0005] This invention addresses the problems of existing technologies by providing a method for synthesizing two-dimensional conjugated coordination polymer (CCP) thin films based on ammonia-assisted chemical vapor deposition. This method significantly improves the crystallinity, electrical conductivity, and mechanical properties of the films. Compared with traditional methods, this invention not only effectively solves the problem of residual protons hindering the assembly of ordered coordination networks, but also avoids adverse factors such as particulate contamination, solution-induced corrosion, and surface tension effects in solution methods. Furthermore, it offers feasibility for large-area fabrication and high control over film growth, seamlessly integrating with existing microfabrication technologies. This represents an innovation in 2D c-CP thin film preparation and possesses significant technological value.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] The first aspect of this invention provides a method for synthesizing two-dimensional conjugated coordination polymer films based on ammonia-assisted chemical vapor deposition, comprising the following steps:
[0008] (1) Prepare two single-ended open reaction tubes and place them face to face in the reaction apparatus. Place the metal salt precursor, ligand and substrate in the reaction tubes respectively. The metal salt precursor and ligand are placed at the sealed end of the two reaction tubes respectively, and the substrate is placed in the middle section of one of the reaction tubes. Place the container filled with ammonia water upstream of the gas flow in the reaction apparatus.
[0009] (2) Purge the reaction apparatus with inert gas, and then evacuate the reaction apparatus to below 1 mbar;
[0010] (3) The metal salt precursor and ligand are heated and reacted for a certain time to obtain the two-dimensional conjugated coordination polymer film.
[0011] Furthermore, the reaction apparatus has a heatable reaction chamber and is equipped with gas purging and vacuuming functions; the preferred reaction apparatus is a tube furnace.
[0012] Furthermore, the metal salt precursor is an iron-based metal salt or a copper-based metal salt, preferably an iron-based metal salt.
[0013] Furthermore, the metal salt is an acetylacetone salt. As a ligand, the acetylacetone metal salt has good thermal stability and coordination ability, and can provide a stable metal ion source at an appropriate temperature, which is beneficial to the formation of high-quality thin films. Otherwise, the precursor salt will not be able to become gaseous molecules and participate in the coordination reaction under suitable conditions.
[0014] Furthermore, the metal salt precursor is iron(III)(Fe(acac)3) acetylacetonate or copper(II)(Cu(acac)2).
[0015] Furthermore, the ligand is a ligand containing a hydroxyl (-OH) group or a mercapto (-SH) group, preferably a ligand containing a hydroxyl (-OH) group.
[0016] Compared to the thiol (-SH) group, the hydroxyl (-OH) group has a higher deprotonation activation energy, which further enhances the role of NH3 in deprotonation.
[0017] Furthermore, the ligand is (HHB) or (BHT).
[0018] The chemical reaction equations for Fe-HHB, Cu-HHB, and Cu-BHT are as follows:
[0019]
[0020]
[0021] The method of this invention significantly improves the crystallinity, electrical, and mechanical properties of thin films by introducing ammonia (NH3) as a deprotonating agent and dynamic coordination modifier. Specifically, NH3 neutralizes the protonated groups of ligands (such as -OH, -SH), eliminating electrostatic repulsion and promoting the assembly of ordered coordination networks of metal-ligands (such as Fe-O, Cu-O, Cu-S); simultaneously, as a competing coordination species, it reversibly regulates the formation and breaking of coordination bonds, reduces grain boundary defects, and increases the domain size by two orders of magnitude (from ~10). 2 nm 2 Increased to ~10 4 nm 2 Taking the Fe-HHB system as an example, the conductivity of the obtained thin film increased from 0.002 S / cm to 3 S / cm, and the charge mobility reached 31 cm⁻¹. 2 / (V·s), the elastic modulus and hardness increased to 43.8GPa and 2.0GPa, respectively.
[0022] This invention preferably uses Fe-based metal salts as precursors and compounds containing hydroxyl (-OH) groups as ligands. The Fe-O bond has a high dissociation energy, therefore ammonia can effectively promote the deprotonation of ligands in Fe-HHB, thus significantly improving crystallinity. In contrast, the Cu-O and Cu-S bonds have lower dissociation energies, making the deprotonation process of ligands in Cu-HHB and Cu-BHT materials more reversible, thereby weakening the deprotonation-promoting effect of NH3. Consequently, the improvement in crystallinity of these materials is not as significant as that of Fe-HHB.
[0023] Furthermore, the mass ratio of the metal salt precursor to the ligand is (0.1-60):1, preferably (1-40):1, and more preferably (2-20):1.
[0024] Furthermore, the substrate is one of silicon oxide wafer, bare silicon wafer, quartz, glass, mica, flexible polymer substrate, and tungsten foil.
[0025] Furthermore, the substrate is pretreated before use. The pretreatment process includes cleaning by alternating ultrasonic treatment with acetone, ethanol and deionized water, and finally drying in an N2 gas flow.
[0026] Furthermore, the concentration of the ammonia water is 0.08-0.3 mol / L, preferably 0.1-0.2 mol / L.
[0027] Furthermore, the volume ratio of the ammonia water to the mass of the ligand is 1 mL: (0.1-20) mg.
[0028] Too low ammonia concentration will not effectively promote product deprotonation, while too high ammonia concentration will generate higher concentrations of NH3 gas during the reaction, which will significantly corrode and decompose the two-dimensional conjugated coordination polymer film (2D c-CP), resulting in the inability to obtain a continuous and relatively flat high-quality film. This is because NH3 will destroy the coordination network of the product and decompose it into smaller fragments or molecules. Taking Fe-HHB as an example, high concentrations of NH3 can break down the original FeO4 bonds of Fe-HHB, replacing the HHB molecule as the main ligand coordinating with the Fe atom. Subsequently, it is carried away by the gas flow, making the sample rough and porous. The reaction equation is as follows:
[0029]
[0030] Furthermore, the container containing ammonia is a tubular container, including but not limited to plastic tubes, glass bottles with silicone diaphragms, rigid silica tubes, quartz tubes, polytetrafluoroethylene tubes, preferably plastic centrifuge tubes, and the container capacity is preferably 0.5-10 mL.
[0031] Furthermore, one end of the tubular container has an opening with a diameter of 0.5-1 mm. If the opening is too large, the water in the container will evaporate too quickly, failing to provide steam for the entire reaction process; if the opening is too small, the amount of ammonia provided during the entire reaction process will be insufficient, thus affecting the quality of the product.
[0032] Furthermore, the two single-ended reaction tubes may have the same or different lengths. Preferably, two single-ended reaction tubes of different lengths are used, and the two reaction tubes are placed face to face, i.e., mouth to mouth.
[0033] A reaction tube system arranged face-to-face prevents reactants from being directly sprayed into the outlet under gas flow. The gap between the two reaction tubes should be minimized to effectively prevent the loss of reactants due to evaporation under gas flow conditions. This design aims to increase the concentration of the activated reactants, thereby improving the quality of the synthesized product.
[0034] Furthermore, the ligand is placed at the sealed end of the longer reaction tube, the metal salt precursor is placed at the sealed end of the shorter reaction tube, and the substrate is placed in the middle region of the longer reaction tube. The middle region refers to any location other than the end of the reaction tube, and is not limited to the center of the reaction tube.
[0035] Furthermore, the ratio of the length of the longer reaction tube to the length of the shorter reaction tube is (1.1-5):1, preferably (2-3):1.
[0036] Furthermore, in the longer reaction tube, the distance between the substrate and the ligand is 1 / 30 to 5 / 6 of the total length of the longer reaction tube.
[0037] Taking Fe-HHB as an example, the schematic diagram of the reaction tube is as follows: Figure 1 As shown, the reaction includes two inner tubes of different lengths. The longer inner tube is 160 mm long, with a sealed end containing HHB ligand powder to maintain a higher HHB ligand concentration during growth (by reducing molecule loss due to evaporation). The substrate is placed in the middle of the longer inner tube, approximately 16-96 mm from the ligand. The shorter inner tube is 65 mm long, with a sealed end containing a metal salt precursor (Fe(acac)3) powder to achieve optimal synthesis results. This is merely an illustrative example and not intended to limit the scope of the invention.
[0038] Further, the inert gas in step (2) is one or more of nitrogen, argon, and helium, with nitrogen being preferred.
[0039] Further, in step (3), the metal salt precursor and ligand are heated to 80-400°C, preferably, the metal salt precursor is heated to 80-120°C and the ligand is heated to 120-250°C.
[0040] Further, in step (3), the metal salt precursor and ligand are heated to the required temperature within 1-20 minutes.
[0041] Furthermore, the reaction time in step (3) is from 10 min to 6 h, excluding the preheating time.
[0042] The second aspect of the present invention provides a two-dimensional conjugated coordination polymer film, which is prepared by the above-mentioned method for synthesizing two-dimensional conjugated coordination polymer films based on ammonia-assisted chemical vapor deposition.
[0043] A third aspect of the present invention provides the application of the two-dimensional conjugated coordination polymer film in the preparation of electronic devices, energy storage devices, and optoelectronic devices.
[0044] Furthermore, the electronic devices, energy storage devices, and optoelectronic devices include, but are not limited to, transistors, sensors, flexible displays, wearable devices, lithium-ion batteries, supercapacitors, solar cells, neuromorphic devices, photodetectors, magnetic storage devices, and spin transistors.
[0045] Compared with the prior art, the present invention has the following beneficial effects:
[0046] 1. This invention prepares two-dimensional conjugated coordination polymer films using NH3-assisted chemical vapor deposition (CVD). It eliminates the need for harsh reaction conditions and cumbersome operating steps, enabling efficient and convenient preparation of high-quality 2D c-CP films. The method significantly simplifies the preparation process and reduces the difficulty of preparation.
[0047] 2. This invention is the first to propose an NH3-assisted CVD method, which significantly improves the performance of 2D c-CP films. Combined with a face-to-face inner tube arrangement and low-pressure control, it effectively prevents reactants from being directly sprayed to the outlet under gas flow, reducing evaporation losses, increasing reactant concentration, and thus improving synthesis efficiency. Furthermore, the method of this invention achieves large-area uniform films (~1cm²). 2 The direct growth of 2D c-CP thin films avoids the complex transfer steps required for traditional liquid gallium substrate synthesis, reduces the risk of contamination, and is seamlessly compatible with existing micro / nano device integration technologies. This innovative process has greatly advanced the development of 2D c-CP thin film fabrication technology.
[0048] 3. This invention significantly improves the crystal domains, electrical conductivity, and mechanical properties of the thin film through the deprotonation and competitive coordination effects of NH3. This can greatly improve the performance of electronic devices and provide a new material basis for the development of high-performance electronic devices.
[0049] 4. The method of synthesizing two-dimensional conjugated coordination polymer films by ammonia-assisted chemical vapor deposition in this invention has universality and is applicable to various 2D c-CP systems such as Fe-HHB, Cu-HHB, and Cu-BHT, providing a general solution for the development of diverse conductive polymers and MOF films.
[0050] 5. The precursor metal salts (such as acetylacetone salts) used in this invention are widely available and low in cost. The preparation process does not use harmful solvents, does not pollute the environment, and meets environmental protection requirements. It is a new mechanism for environmentally friendly and green material preparation. Attached Figure Description
[0051] Figure 1 A schematic diagram of a growth apparatus for synthesizing two-dimensional conjugated coordination polymer films by ammonia-assisted chemical vapor deposition.
[0052] Figure 2 The images show a comparison of SEM images of the Fe-HHB films synthesized in Example 1 (left) and Comparative Example 1 (right).
[0053] Figure 3 Comparison diagrams of the thin film conductivity and powder X-ray diffraction (PXRD) spectra obtained in Comparative Example 3 and Example 5.
[0054] Figure 4 Comparison diagrams of the thin film conductivity and powder X-ray diffraction (PXRD) spectra obtained in Comparative Example 4 and Example 6.
[0055] Figure 5 The images show transmission electron microscopy (TEM) characterizations of the Fe-HHB films prepared in Example 1 and Comparative Example 6.
[0056] Figure 6 The graph shows the statistical analysis of the electrical conductivity (a) and domain size (b) of the Fe-HHB films prepared in Example 1 and Comparative Example 6.
[0057] Figure 7 Figure 1 shows a comparison of the mechanical properties of the Fe-HHB films prepared in Example 1 and Comparative Example 6. In Figure 1, the load-displacement curve is shown, Figure 2 shows the elastic modulus curve, and Figure 3 shows the hardness curve. Detailed Implementation
[0058] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, it is worth noting that the raw materials involved in the present invention are all commercially available products unless otherwise specified.
[0059] Example 1
[0060] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Fe-HHB thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0061] (1) As Figure 1As shown, two single-ended reaction tubes of different lengths are prepared. The longer reaction tube is 160 mm long and 16 mm in diameter. 2 mg of ligand (HHB) powder is placed at its sealed end, and a silicon oxide substrate is placed 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. 20 mg of metal salt precursor (Fe(acac)3) powder is placed at its sealed end. The two reaction tubes are arranged face to face in a tube furnace.
[0062] The silicon oxide substrate is pre-treated, and the treatment process includes ultrasonically treating the silicon oxide substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0063] Prepare an ammonia solution with a concentration of 0.14 mol / L. Place 1 mL of the ammonia solution into a 5 mL plastic centrifuge tube. Make a hole with a diameter of 0.8 mm at one end of the plastic centrifuge tube. Place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0064] (2) First purge the tube furnace with 200 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.5 mbar.
[0065] (3) During the synthesis reaction, the region where HHB is located is heated to 200℃ and the region where Fe(acac)3 is located is heated to 105℃ in 5 min, and the reaction is carried out for 1 h to obtain the two-dimensional conjugated coordination polymer film (2D Fe-HHB film).
[0066] Example 2
[0067] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Cu-BHT thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0068] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 15 mg of ligand (BHT) powder at its sealed end and place a silicon oxide substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 43 mg of metal salt precursor (Cu(acac)2) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0069] The silicon oxide substrate is pre-treated, and the treatment process includes ultrasonically treating the silicon oxide substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0070] Prepare an ammonia solution with a concentration of 0.14 mol / L. Place 2 ml of the ammonia solution into a 5 mL plastic centrifuge tube. Make a hole with a diameter of 0.8 mm at one end of the plastic centrifuge tube. Place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0071] (2) First purge the tube furnace with 200 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.4 mbar.
[0072] (3) During the synthesis reaction, the region where BHT is located is heated to 130°C and the region where Cu(acac)2 is located is heated to 90°C in 9 minutes. The reaction is carried out for 1 hour to obtain the two-dimensional conjugated coordination polymer film (2D Cu-BHT film).
[0073] Example 3
[0074] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Fe-HHB thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0075] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 2 mg of ligand (HHB) powder at its sealed end and place a quartz substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 20 mg of metal salt precursor (Fe(acac)3) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0076] The quartz substrate is pretreated, and the treatment process includes ultrasonically treating the quartz substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0077] Prepare an ammonia solution with a concentration of 0.14 mol / L. Place 2 ml of the ammonia solution into a 5 mL plastic centrifuge tube. Make a hole with a diameter of 0.8 mm at one end of the plastic centrifuge tube. Place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0078] (2) First purge the tube furnace with 500 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.4 mbar.
[0079] (3) During the synthesis reaction, the region where HHB is located is heated to 200℃ and the region where Fe(acac)3 is located is heated to 105℃ in 4 min, and the reaction is carried out for 30 min to obtain the two-dimensional conjugated coordination polymer film (2D Fe-HHB film).
[0080] Example 4
[0081] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Cu-HHB thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0082] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 23 mg of ligand (HHB) powder at its sealed end and place a flexible polyimide organic polymer substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 56 mg of metal salt precursor (Cu(acac)2) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0083] The flexible polyimide organic polymer material substrate is pretreated. The treatment process includes ultrasonically treating the flexible polyimide organic polymer material substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0084] Prepare a 0.14 mol / L ammonia solution by placing 1 mL of the ammonia solution into a 5 mL plastic centrifuge tube. Make a 0.8 mm hole at one end of the plastic centrifuge tube and place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0085] (2) First purge the tube furnace with 500 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.5 mbar.
[0086] (3) During the synthesis reaction, the region where HHB is located is heated to 130℃ and the region where Cu(acac)2 is located is heated to 90℃ in 10 min, and the reaction is carried out for 20 min to obtain the two-dimensional conjugated coordination polymer film (2D Cu-HHB film).
[0087] Example 5
[0088] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Cu-BHT thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0089] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 15 mg of ligand (BHT) powder at its sealed end and place a mica substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 43 mg of metal salt precursor (Cu(acac)2) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0090] The mica substrate is pre-treated, and the treatment process includes ultrasonically treating the mica substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0091] Prepare a 0.14 mol / L ammonia solution by placing 1 mL of the ammonia solution into a 5 mL plastic centrifuge tube. Make a 0.8 mm hole at one end of the plastic centrifuge tube and place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0092] (2) First purge the tube furnace with 500 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.5 mbar.
[0093] (3) During the synthesis reaction, the region where BHT is located is heated to 130°C and the region where Cu(acac)2 is located is heated to 90°C in 10 min. The reaction is carried out for 20 min to obtain the two-dimensional conjugated coordination polymer film (2D Cu-BHT film).
[0094] Example 6
[0095] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Cu-HHB thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0096] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 23 mg of ligand (HHB) powder at its sealed end and place a silicon oxide substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 56 mg of metal salt precursor (Cu(acac)2) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0097] The silicon oxide substrate is pre-treated, and the treatment process includes ultrasonically treating the silicon oxide substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0098] Prepare a 0.14 mol / L ammonia solution by placing 3 mL of the ammonia solution into a 5 mL plastic centrifuge tube. Make a 0.8 mm diameter hole at one end of the plastic centrifuge tube and place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0099] (2) First purge the tube furnace with 200 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.4 mbar.
[0100] (3) During the synthesis reaction, the region where HHB is located is heated to 130℃ and the region where Cu(acac)2 is located is heated to 90℃ in 9 minutes. The reaction is carried out for 1 hour to obtain the two-dimensional conjugated coordination polymer film (2D Cu-HHB film).
[0101] Example 7
[0102] This embodiment provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Fe-HHB thin films) based on ammonia-assisted chemical vapor deposition, including the following steps:
[0103] (1) Prepare two single-ended reaction tubes of different lengths. The longer reaction tube is 160 mm long and 16 mm in diameter. Place 3 mg of ligand (HHB) powder at its sealed end and place a quartz substrate 70 mm away from the ligand powder in the middle section. The shorter reaction tube is 65 mm long and 16 mm in diameter. Place 20 mg of metal salt precursor (Fe(acac)3) powder at its sealed end. Place the two reaction tubes face to face in a tube furnace.
[0104] The quartz substrate is pretreated, and the treatment process includes ultrasonically treating the quartz substrate alternately in acetone, ethanol and deionized water for 20 minutes to clean the surface, and finally drying it in N2 airflow.
[0105] Prepare a 0.14 mol / L ammonia solution by placing 2 ml of the ammonia solution into a 5 mL plastic centrifuge tube. Make a 0.7 mm hole at one end of the plastic centrifuge tube and place the plastic centrifuge tube containing the ammonia solution upstream of the gas flow in the tube furnace.
[0106] (2) First purge the tube furnace with 1000 sccm of nitrogen to remove impurity gases from the system, and then evacuate the tube furnace to a negative pressure of about 0.2 mbar.
[0107] (3) During the synthesis reaction, the region where HHB is located is heated to 200℃ and the region where Fe(acac)3 is located is heated to 105℃ in 3 min, and the reaction is carried out for 2 h to obtain the two-dimensional conjugated coordination polymer film (2D Fe-HHB film).
[0108] Comparative Example 1
[0109] This comparative example provides a method for synthesizing two-dimensional conjugated coordination polymer films (2D Fe-HHB films) based on ammonia-assisted chemical vapor deposition. The difference from Example 1 is that the concentration of ammonia is increased to 2 mol / mL.
[0110] The amount of ammonia released during the synthesis process increased significantly. Excessively high concentrations of NH3 can break down the original FeO4 bonds in Fe-HHB, replacing HHB molecules as the main ligands coordinating with Fe atoms. This excessively high ammonia concentration led to severe side reactions, making the resulting film surface more rough and porous. SEM images of the 2D Fe-HHB films prepared in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown, the left figure is Example 1 and the right figure is Comparative Example 1. It can be observed that the surface of the film synthesized with excessively high concentrations of ammonia water exhibits obvious pores and cracks.
[0111] Comparative Example 2
[0112] This comparative example provides a method for synthesizing two-dimensional conjugated coordination polymer thin films (2D Fe-HHB thin films) based on ammonia-assisted chemical vapor deposition. The difference from Example 3 is that no face-to-face reaction tubes are added in the tube furnace, and the ligands, metal salt precursors, and substrates are placed directly in the tube furnace tubes.
[0113] Because there was no relatively enclosed space provided by the reaction tube to prevent the loss of reactants due to evaporation under gas flow conditions, this comparative example could not obtain the required Fe-HHB film, which directly led to the failure of the experiment.
[0114] Comparative Example 3
[0115] This comparative example provides a method for synthesizing a two-dimensional conjugated coordination polymer film (2D Cu-BHT film) by chemical vapor deposition. The difference from Example 5 is that no container holding ammonia water was added during the growth of Cu-BHT, i.e., no NH3 was used to assist in the growth of Cu-BHT-o.
[0116] The sample obtained in Example 5 is designated Cu-BHT-w. The conductivity and powder X-ray diffraction (PXRD) spectra of the Cu-BHT thin films obtained in Comparative Example 3 and Example 5 are shown below. Figure 3 As shown, by Figure 3It can be seen that the full width at half maximum (FWHM) of the (100) peak in the PXRD pattern decreased significantly, indicating that Cu-BHT-w exhibits higher crystallinity than Cu-BHT-o. In addition, the electrical conductivity of the Cu-BHT-w film increased by 1.5 times (from ~595 S / cm to ~905 S / cm), indicating that the synthesis method using NH3-assisted CVD significantly improved the crystallinity and electrical conductivity of the Cu-BHT film.
[0117] Comparative Example 4
[0118] This comparative example provides a method for synthesizing two-dimensional conjugated coordination polymer films (2D Cu-HHB films) by chemical vapor deposition. The difference from Example 6 is that no container holding ammonia water was added during the growth of Cu-HHB, i.e., no NH3 was used to assist in the growth of Cu-HHB-o.
[0119] The sample obtained in Example 6 is denoted as Cu-HHB-w. The electrical conductivity and powder X-ray diffraction (PXRD) spectra of the Cu-HHB thin films obtained in Comparative Example 4 and Example 6 are shown below. Figure 4 As shown, by Figure 4 It can be seen that the full width at half maximum (FWHM) of the (100) peak in the PXRD pattern decreases significantly, indicating that Cu-HHB-w exhibits higher crystallinity than Cu-HHB-o. In addition, the Cu-HHB-w film exhibits a high conductivity of ~113 S / cm, which is more than twice that of Cu-HHB-o (~51 S / cm). This suggests that using an NH3-assisted strategy to improve the crystallinity of CVD Cu-HHB films can lead to higher conductivity.
[0120] Comparative Example 5
[0121] This comparative example provides a method for synthesizing two-dimensional conjugated coordination polymer films (2D Fe-HHB films) based on ammonia-assisted chemical vapor deposition. The difference from Example 1 is that the metal salt precursor Fe(acac)3 is replaced with ferric chloride. This is because ferric chloride hydrolyzes to generate ferric hydroxide and hydrogen chloride gas when heated, instead of sublimating, which directly leads to the failure of Fe-HHB film synthesis.
[0122] Comparative Example 6
[0123] This comparative example provides a method for synthesizing two-dimensional conjugated coordination polymer films (2D Fe-HHB films) by chemical vapor deposition. The difference from Example 1 is that no container holding ammonia water was added during the growth of Fe-HHB, i.e., no NH3 was used to assist in the growth of Fe-HHB-o.
[0124] The sample obtained in Example 1 is designated Fe-HHB-w. Transmission electron microscopy (TEM) images of the Fe-HHB films obtained in Example 1 and Comparative Example 6 are shown below. Figure 5 As shown. By Figure 5 It can be seen that the Fe-HHB-w thin film ~10 4 nm 2 The region exhibits a well-preserved periodic structure, and the corresponding Fast Fourier Transform (FFT) image shows a typical hexagonal diffraction pattern; while the Fe-HHB-o sample exhibits smaller crystal domains (~10). 2 nm 2 The film exhibits obvious orientation errors and large amorphous regions, resulting in a significant decrease in film crystallinity.
[0125] The statistical analysis of the conductivity (a) and domain size (b) of the Fe-HHB thin films prepared in Example 1 and Comparative Example 6 is shown in the figure below. Figure 6 As shown, by Figure 6 It can be seen that the domain size of the Fe-HHB-w film is increased by two orders of magnitude compared to the Fe-HHB-o film (from ~10). 2 nm 2 Increased to ~10 4 nm 2 The electrical conductivity (σ) of Fe-HHB-o thin films (~2×10⁻⁶) -3 The S / cm ratio decreased by approximately three orders of magnitude compared to Fe-HHB-w (~3S / cm).
[0126] The mechanical properties of the Fe-HHB films prepared in Example 1 and Comparative Example 6 are compared as shown in the figure. Figure 7 As shown, the mechanical properties of the products synthesized under ammonia-assisted conditions (Fe-HHB-w) and ammonia-free conditions (Fe-HHB-o) were evaluated using nanoindentation testing. Figure a shows the load-displacement curves. Under the same load, the indentation depth of Fe-HHB-w was consistently lower than that of Fe-HHB-o, indicating its greater resistance to deformation. This is mainly attributed to the high structural integrity of the Fe-HHB-w crystalline region, which effectively resists dislocation movement. Furthermore, the Fe-O bonds in the Fe-HHB-w film have a higher dissociation energy, further enhancing its mechanical properties. Figure b shows the elastic modulus diagram, and Figure c shows the hardness diagram. The average hardness of the Fe-HHB-w film is approximately 2.0 GPa, and the elastic modulus is approximately 43.8 GPa, significantly exceeding that of Fe-HHB-o (average hardness approximately 0.9 GPa, elastic modulus approximately 25.7 GPa). The above results indicate that the product Fe-HHB-w synthesized with ammonia has superior mechanical properties and is expected to be widely used in fields with high requirements for material performance, such as high-durability wearable devices.
[0127] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.
Claims
1. A method for synthesizing two-dimensional conjugated coordination polymer films based on ammonia-assisted chemical vapor deposition, comprising the following steps: (1) Prepare two single-end open reaction tubes, place them face to face in the reaction apparatus, and place the metal salt precursor, ligand, and substrate in the reaction tubes respectively. The metal salt precursor and ligand are placed at the sealed ends of the two reaction tubes, and the substrate is placed in the middle section of one of the reaction tubes; a container filled with ammonia is placed upstream of the gas flow in the reaction apparatus. (2) Purge the reaction apparatus with inert gas, and then evacuate the reaction apparatus to below 1 mbar; (3) The metal salt precursor and ligand are heated and reacted for a certain time to obtain the two-dimensional conjugated coordination polymer film.
2. The method according to claim 1, characterized in that: The metal salt precursor is an iron-based metal salt or a copper-based metal salt.
3. The method according to claim 2, characterized in that: The metal salt is acetylacetone.
4. The method according to claim 3, characterized in that: The metal salt precursor is iron acetylacetonate (III) or copper acetylacetonate (II).
5. The method according to claim 1, characterized in that: The ligand is a ligand containing a hydroxyl group or a thiol group.
6. The method according to claim 5, characterized in that: The ligand is 7. The method according to claim 1, characterized in that: The mass ratio of the metal salt precursor to the ligand is (0.1-60):1, preferably (1-40):1, and more preferably (2-20):
1.
8. The method according to claim 1, characterized in that: The substrate is one of the following: silicon oxide wafer, bare silicon wafer, quartz, glass, mica, flexible polymer substrate, and tungsten foil.
9. The method according to claim 8, characterized in that: The substrate is to be pretreated before use. The pretreatment process includes cleaning the substrate by alternating ultrasonic treatment with acetone, ethanol and deionized water, and finally drying it in N2 gas flow.
10. The method according to claim 1, characterized in that: The concentration of the ammonia water is 0.08-0.3 mol / L, preferably 0.1-0.2 mol / L.
11. The method according to claim 1, characterized in that: The volume ratio of the ammonia water to the mass of the ligand is 1 mL: (0.1-20) mg.
12. The method according to claim 1, characterized in that: The container containing ammonia is a tubular container, and one end of the tubular container has an opening with a diameter of 0.5-1 mm.
13. The method according to claim 1, characterized in that: The two single-ended reaction tubes may have the same or different lengths.
14. The method according to claim 13, characterized in that: The two single-ended reaction tubes are of different lengths.
15. The method according to claim 14, characterized in that: The ratio of the length of the longer reaction tube to the length of the shorter reaction tube in the two single-ended reaction tubes is (1.1-5):1, preferably (2-3):
1.
16. The method according to claim 15, characterized in that: The ligand is placed at the sealed end of the longer reaction tube, the metal salt precursor is placed at the sealed end of the shorter reaction tube, and the substrate is placed in the middle section of the longer reaction tube.
17. The method according to claim 16, characterized in that: In the longer reaction tube, the distance between the substrate and the ligand is 1 / 30 to 5 / 6 of the total length of the longer reaction tube.
18. The method according to claim 1, characterized in that: The inert gas mentioned in step (2) is one or more of nitrogen, argon, and helium.
19. The method according to claim 1, characterized in that: Step (3) Heat the metal salt precursor and ligand to 80-400°C. Preferably, heat the metal salt precursor to 80-120°C and the ligand to 120-250°C.
20. The method according to claim 19, characterized in that: Step (3) Heat the metal salt precursor and ligand to the required temperature within 1-20 minutes.
21. The method according to claim 1, characterized in that: The reaction time in step (3) is from 10 min to 6 h.
22. A two-dimensional conjugated coordination polymer film, characterized in that: It is prepared by the method described in any one of claims 1-21.
23. The application of the two-dimensional conjugated coordination polymer film according to claim 22 in the preparation of electronic devices, energy storage devices, and optoelectronic devices.