Synthesis method of coordination polymer, coordination polymer composite heterojunction and application of coordination polymer composite heterojunction

Abstract

The invention relates to a chemical vapor deposition synthesis method of a coordination polymer, and preparation and application of a coordination polymer composite heterojunction, belongs to the technical field of coordination polymers, and solves the problems that a coordination polymer prepared by an existing chemical vapor deposition method is low in crystallinity, difficult to reach a thin layer, non-uniform in structural physical property, low in cost and the like. And the transmission performance is poor. The method comprises the steps that a first precursor and a second precursor are placed in two temperature zones respectively for a liquid-assisted chemical vapor deposition reaction, a growth zone is located in the temperature zone capable of forming a temporary liquid phase environment, vapor of the first precursor and vapor of the second precursor react in a liquid phase after being diffused to the growth zone, and the first precursor and the second precursor are separated from each other. Therefore, a high-quality coordination polymer and single crystal coordination polymer composite heterojunction is grown. The method is simple and easy to operate, the process is controllable, and the obtained material is good in morphology and excellent in performance and has wide application prospects in the fields of sensors and photoelectricity.

Description

Technical Field

[0001] This invention relates to the field of coordination polymer technology, and in particular to a method for preparing coordination polymers, a single-crystal coordination polymer composite heterojunction, its preparation method and application. Background Art

[0002] Coordination polymers are crystals with a periodic network structure formed by the coordination of organic ligands and metal ion centers. Coordination polymers combine the properties of both organic and inorganic materials, exhibiting characteristics such as designable and tunable structure, large specific surface area, and adjustable pore size. They have been extensively studied not only in fundamental fields such as catalytic intermediate capture and energy transfer, but also in their potential practical applications, including gas storage and separation, heterogeneous catalysis, and chemical sensing.

[0003] Coordination polymers prepared using existing chemical vapor deposition methods exhibit low crystallinity, making it difficult to obtain thin layers. Their structural physical properties are also non-uniform, resulting in poor transmission performance when applied to sensors. Furthermore, current techniques for preparing coordination polymer composite heterostructures primarily rely on mechanical transfer methods, and there is currently no direct growth method for preparing high-quality coordination polymer composite heterostructures. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a coordination polymer, a composite heterojunction, a preparation method and application, which can at least solve one of the following technical problems: (1) The coordination polymer prepared by the existing chemical vapor deposition method has low crystallinity and uneven physical properties in structure. At the same time, it is difficult to obtain two-dimensional coordination polymers, resulting in poor transmission performance when applied to sensors; (2) The existing method cannot directly grow the coordination polymer composite heterojunction, but relies on mechanical transfer technology. During the transfer process, the composite heterojunction is easily damaged and contaminated, and the coordination polymer and the two-dimensional material may not adhere tightly after transfer.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for synthesizing coordination polymers by chemical vapor deposition, wherein the chemical vapor deposition includes liquid-assisted chemical vapor deposition; and the coordination polymer includes coordination polymer single crystals.

[0007] Preferably, the coordination polymer comprises a two-dimensional coordination polymer single crystal.

[0008] The synthesis method includes the following steps:

[0009] Step 1: Place the first precursor and the second precursor in the first temperature zone and the second temperature zone, respectively;

[0010] Step 2: Heat the first and second temperature zones in the atmosphere to sublimate the first and second precursors into vapor, and maintain the temperature.

[0011] Step 3: The vapors of the first precursor and the second precursor diffuse onto the growth substrate located in the growth region, and react in the liquid located on the substrate surface to obtain the coordination polymer;

[0012] The growth zone is located in a temperature range where a temporary liquid phase environment can be formed.

[0013] Optionally, in step 3, the liquid is formed by an organic solvent adhering to the surface of the substrate, and / or by the self-condensation of the vapor of the first precursor or the vapor of the second precursor on the surface of the substrate.

[0014] Optionally, the coordination polymer comprises a single-layer coordination polymer crystal.

[0015] Optionally, the coordination polymer comprises a metal M and a ligand X; the metal comprises at least one selected from iron, copper, zinc, molybdenum, cobalt, manganese, chromium, nickel, and tungsten, preferably at least one selected from iron, zinc, cobalt, manganese, and nickel;

[0016] Optionally, the ligand X includes at least one of benzimidazole, 5-methylbenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, and 5-aminobenzimidazole.

[0017] Secondly, the present invention provides a single-crystal coordination polymer composite heterojunction, comprising a coordination polymer single crystal and a two-dimensional material prepared by the above-described synthesis method.

[0018] Optionally, the two-dimensional material includes at least one of transition metal dichalcogenides, graphene, hexagonal boron nitride, and covalent organic frameworks.

[0019] Thirdly, the present invention also provides a method for preparing a coordination polymer composite heterojunction, which is used to prepare the above-mentioned composite heterojunction, comprising the following steps:

[0020] Step i: Place the first precursor and the second precursor in the first temperature zone and the second temperature zone, respectively;

[0021] Step ii: Heat the first and second temperature zones in the atmosphere to sublimate the first and second precursors into vapor, and maintain the temperature;

[0022] Step iii: The vapors of the first precursor and the second precursor diffuse into the substrate located in the growth region and whose surface is covered with a two-dimensional material, and a chemical vapor deposition reaction is carried out in the liquid located on the surface of the substrate to obtain a coordination polymer composite heterojunction;

[0023] The growth zone is located in a temperature range where a temporary liquid phase environment can be formed.

[0024] Fourthly, the present invention also provides an application of the above-mentioned coordination polymer and the above-mentioned composite heterojunction in the fields of sensors and optoelectronics.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] (1) Coordination polymers prepared using existing chemical vapor deposition methods have low crystallinity and uneven physical properties, resulting in poor transmission performance when applied to sensors. This invention directly obtains highly crystalline coordination polymers by sublimating the first and second precursors into vapors dissolved in a liquid, followed by chemical vapor deposition in the liquid. Figure 19 It contains sharp characteristic peaks, and the sharper the peak, the higher the crystallinity, even in coordination polymers with single-crystal structures. Figure 6 Compared to polycrystalline or amorphous structures with low crystallinity, single-crystal coordination polymer molecules and atoms exhibit long-range order and uniform physical properties. They are free from defects such as grain boundaries, lattice dislocations, or vacancies, thus providing superior transmission performance when applied to sensors.

[0027] (2) Traditional chemical vapor deposition (CVD) typically involves reactions at high temperatures (>700°C). Ligand molecules are difficult to maintain stability at such high temperatures, and their large volume and weight limit their transport distance within the tube furnace after vaporization. This invention presents a liquid-assisted CVD method that introduces a temporary liquid environment. In this liquid phase, ligands are less affected by volume and weight, allowing for easier free diffusion and uniform distribution. Furthermore, the liquid environment reduces external interference with coordination polymer growth, enabling growth at low temperatures. Therefore, this invention achieves the preparation of high-quality, highly crystalline coordination polymers at low temperatures (<500°C).

[0028] (3) The coordination polymer prepared by the liquid-assisted chemical vapor deposition method of the present invention has the characteristics of large size (lateral size of 1μm to 10mm), cleanliness and high crystallinity, and can even obtain single-layer (1 molecular layer) coordination polymer single crystal.

[0029] (4) Existing methods cannot directly prepare coordination polymer heterostructures; instead, they rely on mechanical transfer techniques. The preparation method of this invention enables the direct preparation of high-quality, high-crystallinity coordination polymer heterostructures.

[0030] (5) The method of the present invention is simple and easy to operate, and the process is controllable. The resulting coordination polymer and coordination polymer heterostructure have good morphology and excellent performance, and have broad application prospects in the field of sensors.

[0031] (6) The layered structure of the coordination polymer of the present invention has a clean and flat surface with an average roughness of less than 0.5 nm, which makes it suitable for sensor transmission performance and better transport capacity.

[0032] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0034] Figure 1 This is a schematic diagram of the liquid-assisted chemical vapor deposition system used in Embodiment 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the liquid-assisted chemical vapor deposition principle in Embodiment 1 of the present invention;

[0036] Figure 3 An optical microscope image of the iron (benzimidazole) polymer prepared in Example 1 of this invention;

[0037] Figure 4 These are atomic force microscopy height images of the monolayer iron (benzimidazole) polymer (a) and the two-dimensional iron (benzimidazole) polymer (b) prepared in Example 1 of the present invention.

[0038] Figure 5 A three-dimensional atomic force microscope image of the iron (benzimidazole) polymer prepared in Example 1 of this invention;

[0039] Figure 6 The images show a low-resolution transmission electron microscope (a) and a multi-region selected area electron diffraction (B) pattern of the iron (benzimidazole) polymer prepared in Example 1 of this invention.

[0040] Figure 7 The energy dispersive X-ray spectrum of the iron (benzimidazole) polymer prepared in Example 1 of this invention is shown below.

[0041] Figure 8 This is a high-resolution transmission electron microscope image of the iron (benzimidazole) polymer prepared in Example 1 of the present invention;

[0042] Figure 9This is a high-resolution atomic force microscope image of the iron (benzimidazole) polymer prepared in Example 1 of the present invention;

[0043] Figure 10 This is a schematic diagram of the single-crystal structure of the iron (benzimidazole) polymer prepared in Example 1 of the present invention;

[0044] Figure 11 This is a schematic diagram of the interlayer structure of the iron (benzimidazole) polymer prepared in Example 1 of the present invention;

[0045] Figure 12 This is an optical microscope image of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction prepared in Example 2 of the present invention;

[0046] Figure 13 This is a transmission electron microscope image of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction prepared in Example 2 of the present invention;

[0047] Figure 14 This is a schematic diagram of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction device prepared in Example 2 of the present invention;

[0048] Figure 15 This is an optical microscope image of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction device prepared in Example 2 of the present invention;

[0049] Figure 16 This is a graph showing the high selectivity response performance of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction prepared in Example 2 of the present invention;

[0050] Figure 17 This is a normalized sensing performance diagram of the iron (benzimidazole) polymer / molybdenum disulfide heterojunction prepared in Example 2 of the present invention;

[0051] Figure 18 An optical microscope image of the iron (benzimidazole) polymer prepared in Example 3 of this invention;

[0052] Figure 19 The image shows the X-ray diffraction pattern of the polycrystalline iron (benzimidazole) polymer prepared in Example 3 of this invention.

[0053] Figure label:

[0054] 1-First precursor; 2-Second precursor; 3-First temperature zone; 4-Second temperature zone; 5-Growth region; 6-Substrate; 7-Liquid. Detailed Implementation

[0055] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0056] In a first aspect, the present invention provides a method for preparing coordination polymers. Specifically, the present invention uses a liquid-assisted chemical vapor deposition method to prepare large-size, highly crystalline coordination polymers, and even monolayer coordination polymer single crystals, comprising the following steps:

[0057] Step 1: Place the first precursor 1 and the second precursor 2 in the first temperature zone 3 and the second temperature zone 4, respectively;

[0058] Step 2: Heat the first temperature zone 3 and the second temperature zone 4 in the atmosphere to sublimate the first precursor 1 and the second precursor 2 into vapor, and keep them at that temperature for a period of time.

[0059] Step 3: The vapor of the first precursor 1 and the vapor of the second precursor 2 diffuse onto the substrate 6 located in the growth region 5, and a chemical vapor deposition reaction is carried out in the liquid 7 located on the surface of the substrate 6 to obtain the coordination polymer.

[0060] The principle of the above preparation method is as follows: the first precursor sublimates in the first temperature zone, the second precursor sublimates in the second temperature zone, and the vapors of the first and second precursors diffuse into the growth zone. The growth zone is a temperature zone in which a temporary liquid phase environment can be formed. The substrate is located in the growth zone, and its surface may be covered with liquid. The vapors of the first and second precursors diffused into the growth zone dissolve in the liquid and react in the liquid, thereby realizing the growth of coordination polymers on the substrate.

[0061] It should be noted that the coordination polymer described in step 3 includes metal M and ligand X;

[0062] Specifically, metal M includes at least one of iron, copper, zinc, molybdenum, cobalt, manganese, chromium, nickel, and tungsten, preferably at least one of iron, zinc, cobalt, manganese, and nickel;

[0063] Specifically, the ligand X includes at least one of benzimidazole, 5-methylbenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, and 5-aminobenzimidazole.

[0064] It should be noted that the first precursor includes the aforementioned metal M; the second precursor includes the aforementioned ligand X.

[0065] Specifically, in step 1, the molar ratio of the first precursor to the second precursor is 50:1 to 1:50, for example, 50:1, 40:1, 30:1, 20:1, 10:1, 1:1, 1:10, 1:20, 1:30, 1:40, or 1:50, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0066] It should be noted that in step 2, the temperature of the first temperature zone 3 is 40-200℃, for example, 40℃, 60℃, 80℃, 100℃, 120℃, 140℃, 150℃, 170℃, 180℃, 200℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0067] The temperature in the second temperature zone 4 is 50-500℃, for example, 50℃, 80℃, 100℃, 120℃, 150℃, 180℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The temperature selection is adaptively adjusted according to the change of ligand.

[0068] Specifically, in step 2, the heat preservation time is from 1 minute to 10 hours, for example, 1 minute, 5 minutes, 15 minutes, 45 minutes, 60 minutes, 1.5 hours, 3 hours, 4 hours, 5 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0069] Specifically, in step 2, the atmosphere is at least one of nitrogen, argon, helium, neon, krypton, xenon, hydrogen sulfide, oxygen, hydrogen, ammonia, and hydrogen selenide.

[0070] Specifically, in step 3, the liquid is formed from an organic solvent adhering to the substrate surface of the coordination polymer to be grown, and / or from the self-condensation of the vapors of the first precursor and the second precursor on the surface of the substrate of the coordination polymer to be grown. Therefore, the liquid composition includes an organic solvent, and / or components of the first or second precursor.

[0071] Specifically, the organic solvent must satisfy at least one of the following:

[0072] (1) The boiling point of the organic solvent is from 50°C to 1000°C, for example 50°C, 153°C, 259°C, 290°C, 350°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0073] (2) The dielectric constant of the organic solvent is greater than 4, for example, 4, 13, 20 or 37, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0074] (3) The polarity of the organic solvent is greater than 1.2, such as 1.6, 2.5, 2.9 or 3.7, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0075] (4) The molecular weight of the organic solvent is 30 to 1000, such as 30, 73, 92, 170, 740 or 960, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0076] It should be noted that if the boiling point of the organic solvent is too low, the formed liquid will evaporate before the reaction, failing to dissolve the first and second precursors. If the boiling point of the organic solvent is too high, it will remain on the surface of the coordination polymer and cannot be completely removed, affecting the quality of the prepared coordination polymer.

[0077] Specifically, the organic solvents include one or more of N,N-dimethylformamide, benzyl alcohol, glycerol, and diphenyl ether.

[0078] Specifically, the substrate includes at least one of a single-crystal substrate, a polycrystalline substrate, and an amorphous substrate, such as at least one of Si / SiO2, quartz, glass, sapphire, mica, silicon nitride, potassium bromide, copper foil, and single-crystal silicon. In a second aspect, the present invention provides a method for preparing a coordination polymer composite heterojunction, comprising the following steps:

[0079] Step i: Place the first precursor 1 and the second precursor 2 in the first temperature zone 3 and the second temperature zone 4, respectively;

[0080] Step ii: Heat the first temperature zone 3 and the second temperature zone 4 in the atmosphere to sublimate the first precursor 1 and the second precursor 2 into vapor, and keep it at that temperature for a period of time.

[0081] Step iii: The vapor of the first precursor 1 and the vapor of the second precursor 2 diffuse into the substrate 6 located in the growth region 5 and whose surface is covered with a two-dimensional material. A chemical vapor deposition reaction is carried out in the liquid located on the surface of the substrate 6 to obtain a coordination polymer, and at the same time, a coordination polymer composite heterojunction formed by the coordination polymer and the two-dimensional material is obtained.

[0082] It should be noted that the coordination polymer composite heterojunction is formed by the coordination polymer and the two-dimensional material. Therefore, the coordination polymer composite heterojunction is obtained at the same time as the coordination polymer.

[0083] Specifically, in step iii, the two-dimensional material is located on one side of the substrate where the coordination polymer is to be grown. The two-dimensional material includes at least one of transition metal disulfide, graphene, hexagonal boron nitride, and covalent organic framework. Specifically, the two-dimensional material includes one or more of molybdenum disulfide, tungsten disulfide, and graphene.

[0084] The principle of the above preparation method is as follows: the first precursor sublimates in the first temperature zone, the second precursor sublimates in the second temperature zone, and the vapors of the first and second precursors diffuse into the growth zone after sublimation. The growth zone is a temperature zone in which a temporary liquid phase environment can be formed. The substrate is located in the growth zone, and its surface is covered with liquid. The vapors of the first and second precursors diffused into the growth zone dissolve in the liquid and react in the liquid, thereby realizing the growth of coordination polymer on the substrate and obtaining a coordination polymer composite heterojunction formed by coordination polymer and two-dimensional material.

[0085] It should be noted that in step ii, the temperature of the first temperature zone 3 is 40-200℃, for example, 40℃, 60℃, 80℃, 100℃, 120℃, 140℃, 150℃, 170℃, 180℃, 200℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0086] The temperature in the second temperature zone 4 is 50-500℃, for example, 50℃, 80℃, 100℃, 120℃, 150℃, 180℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The temperature selection is adaptively adjusted according to the change of ligand.

[0087] Specifically, in step ii, the heat preservation time is from 1 minute to 10 hours, for example, 1 minute, 5 minutes, 15 minutes, 45 minutes, 60 minutes, 1.5 hours, 3 hours, 4 hours, 5 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0088] Specifically, in step ii, the atmosphere is at least one of nitrogen, argon, helium, neon, krypton, xenon, hydrogen sulfide, oxygen, hydrogen, ammonia, and hydrogen selenide.

[0089] Specifically, in step iii, the liquid is formed from an organic solvent adhering to the substrate surface of the coordination polymer to be grown, and / or from the self-condensation of the vapors of the first precursor and the second precursor on the surface of the substrate of the coordination polymer to be grown. Therefore, the liquid comprises an organic solvent, and / or the components of the first and second precursors.

[0090] Specifically, the organic solvent must satisfy at least one of the following:

[0091] (1) The boiling point of the organic solvent is from 50°C to 1000°C, for example, 50°C, 153°C, 259°C or 290°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0092] (2) The dielectric constant of the organic solvent is greater than 4, for example, 4, 13, 20 or 37, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0093] (3) The polarity of the organic solvent is greater than 1.2, such as 1.6, 2.5, 2.9 or 3.7, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0094] (4) The molecular weight of the organic solvent is 30 to 1000, such as 30, 73, 92, 170, 740 or 960, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0095] It should be noted that if the boiling point of the organic solvent is too low, the formed liquid will evaporate before the reaction, failing to dissolve the first and second precursors. If the boiling point of the organic solvent is too high, it will remain on the surface of the coordination polymer composite heterojunction and cannot be completely removed, affecting the quality of the prepared coordination polymer composite heterojunction.

[0096] Specifically, the organic solvents include one or more of N,N-dimethylformamide, benzyl alcohol, glycerol, and diphenyl ether.

[0097] Given that the surface of substrate 6 is covered with a two-dimensional material, the use of organic solvents may dissolve the two-dimensional material, thereby affecting the quality of the coordination polymer heterojunction. Therefore, in a preferred embodiment, the liquid is formed by the self-condensation of the vapors of the first precursor and the second precursor on the surface of the substrate where the coordination polymer is to be grown, and is not formed by organic solvents adhering to the substrate surface.

[0098] Specifically, the substrate includes at least one of single-crystal substrates, polycrystalline substrates, and amorphous substrates, such as at least one of Si / SiO2, quartz, glass, sapphire, mica, silicon nitride, potassium bromide, copper foil, and single-crystal silicon.

[0099] Thirdly, the present invention provides a single-crystal coordination polymer composite heterojunction synthesized by the above-described method, the composite heterojunction comprising the above-described coordination polymer single crystal and a two-dimensional material. The coordination polymer is the above-described coordination polymer single crystal, or a coordination polymer single crystal prepared using the above-described preparation method. The two-dimensional material is the above-described two-dimensional material attached to a substrate.

[0100] Fourthly, the present invention also provides the application of the above-mentioned coordination polymer and coordination polymer composite heterojunction in the field of sensors.

[0101] Specifically, the aforementioned coordination polymers and coordination polymer composite heterojunctions are used in the field of sensors for highly selective gas response.

[0102] Specifically, the highly selective gas includes at least one of ammonia, hydrogen, and carbon dioxide, with ammonia being preferred.

[0103] Fifthly, the present invention also provides a sensor comprising the aforementioned coordination polymer composite heterojunction.

[0104] Example 1

[0105] This embodiment provides a liquid-assisted chemical vapor deposition synthesis method for coordination polymers, as illustrated in the schematic diagram below. Figure 1 As shown, the schematic diagram is as follows: Figure 2 As shown, the following steps are included:

[0106] 18 mg of benzimidazole and 28 mg of ferrocene (molar ratio 1:1) were respectively placed at both ends of a single-ended sealed inner tube. A clean Si / SiO2 substrate, polished side up, was placed between the benzimidazole and ferrocene. The inner tube was transferred to a dual-temperature zone tube furnace, with the ferrocene and benzimidazole located in temperature zone 1 and temperature zone 2, respectively. The substrate was located in the growth zone between the two temperature zones, with temperature zone 2 upstream of the nitrogen flow. Before growth, the system was evacuated, and then the furnace cavity was purged with nitrogen. A nitrogen flow of 5 sccm was maintained throughout the growth process. Temperature zones 1 and 2 were temperature-controlled, with temperature zone 1 reaching T1 (150°C in this case) and temperature zone 2 reaching T2 (400°C in this case), and held at these temperatures for 15 minutes. The furnace cavity was then evacuated and cooled to obtain the iron (benzimidazole) polymer.

[0107] The prepared iron (benzimidazole) polymer was subjected to optical microscopy, scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and high-resolution atomic force microscopy, respectively. Its morphology and crystal structure information are shown below. Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown, a schematic diagram of the crystal structure of the iron (benzimidazole) polymer is as follows. Figure 10 , Figure 11 As shown.

[0108] In this embodiment, by Figure 3 and Figure 6 (a) It can be seen that the lateral dimensions of the iron (benzimidazole) polymer distribution range from 10 μm to 200 μm; Figure 4 It can be seen that the surface of the iron (benzimidazole) polymer is clean, the thickness of a single-layer iron (benzimidazole) polymer crystal is 1.1 nm, and the thickness of a two-dimensional iron (benzimidazole) polymer crystal is 3.5 nm; from Figure 5 It can be seen that the surface of the iron (benzimidazole) polymer is smooth, with an average roughness of 0.222 nm; from Figure 7 It can be seen that the elements are evenly distributed, and the atomic ratio of iron atoms to nitrogen atoms is 1:4; from Figure 8 and Figure 9 It can be seen that iron (benzimidazole) polymers have good quality and high crystallinity, due to... Figure 6 (b) It can be seen that selected area electron diffraction tests were performed on multiple regions of an iron (benzimidazole) polymer sheet. The test results showed that only one set of quasi-quadruple symmetric diffraction spots were observed in each region, indicating that these regions are all single crystal structures. Furthermore, the SAED pattern showed that the lattice orientation of these regions is almost consistent. The above results confirm that the entire iron (benzimidazole) polymer sheet is a single crystal.

[0109] Example 1-1

[0110] Compared to Example 1, the only difference is that the temperature T1 is controlled at 40°C and the temperature T2 is controlled at 500°C. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0111] Examples 1-2

[0112] Compared to Example 1, the only difference is that the temperature T1 is controlled at 200°C and the temperature T2 is controlled at 50°C. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0113] Examples 1-3

[0114] Compared to Example 1, the only difference is that the heat preservation time is controlled at 1 minute. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0115] Examples 1-4

[0116] Compared to Example 1, the only difference is that the heat preservation time is controlled at 10 hours. Everything else is the same as in Example 1, resulting in an iron (benzimidazole) polymer with the same structure and similar effects.

[0117] Examples 1-5

[0118] Compared to Example 1, the only difference is that the molar ratio of the first precursor to the second precursor is 50:1. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0119] Examples 1-6

[0120] Compared to Example 1, the only difference is that the molar ratio of the first precursor to the second precursor is 1:30. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0121] Examples 1-7

[0122] Compared to Example 1, the only difference is that the molar ratio of the first precursor to the second precursor is 1:50. Everything else is the same as in Example 1, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0123] Example 2

[0124] This embodiment provides a liquid-assisted chemical vapor deposition method for synthesizing coordination polymer composite heterojunctions, the method comprising the following steps:

[0125] 28 mg of ferrocene and 18 mg of benzimidazole were respectively placed at both ends of a single-ended sealed inner tube. A Si / SiO2 substrate with a monolayer of molybdenum disulfide attached to its surface was placed between the benzimidazole and ferrocene. The inner tube was transferred to a dual-temperature zone tube furnace, with the ferrocene and benzimidazole located in temperature zone 1 and temperature zone 2, respectively. The substrate was located in the growth region between the two temperature zones, with temperature zone 2 upstream of the argon gas flow. Before growth, the system was evacuated, and then the furnace cavity was purged with argon gas. An argon gas flow of 10 sccm was maintained throughout the growth process. The temperatures of temperature zones 1 and 2 were controlled, with temperature zone 1 reaching 150°C and temperature zone 2 reaching 400°C, and held at these temperatures for 15 minutes. The furnace cavity was then evacuated and cooled to obtain an iron (benzimidazole) polymer / molybdenum disulfide heterojunction.

[0126] The prepared iron (benzimidazole) polymer / molybdenum disulfide heterojunction was subjected to optical microscopy and transmission electron microscopy, respectively, and its morphology and structure are shown in the figures below. Figure 12 and Figure 13 As shown; by Figure 13As can be seen, multi-region electron diffraction (SED) tests revealed only one set of quasi-quadruple symmetric diffraction spots and one set of hexagonal symmetric diffraction spots in each region, corresponding to the iron (benzimidazole) polymer and molybdenum disulfide, respectively. This indicates that both the iron (benzimidazole) polymer and molybdenum disulfide in these regions are single-crystal structures. Furthermore, the SAED patterns show that the two sets of lattice orientations in these regions are consistent. These results confirm that in the iron (benzimidazole) polymer / molybdenum disulfide heterojunction, both the iron (benzimidazole) polymer and the monolayer molybdenum disulfide are single-crystal structures. The obtained material was fabricated into a sensor device, and a schematic diagram of the sensor device is shown below. Figure 14 As shown, the optical microscope image of the sensor device is as follows: Figure 15 As shown; the sensor device is applied to a mixture of ammonia (NH3), tert-butylamine (TBA), tert-amylamine (TPA), isopropylamine (IPA), and 2-butylamine (2-BA) for high selectivity response to ammonia. The test results are as follows. Figure 16 and Figure 17 As shown.

[0127] Example 2-1

[0128] Compared to Example 2, the only difference is that the substrate is a Si / SiO2 substrate with a single layer of tungsten disulfide attached to its surface. Everything else is the same as in Example 2, and a similar iron (benzimidazole) polymer / tungsten disulfide heterojunction can be obtained.

[0129] Example 2-2

[0130] Compared to Example 2, the only difference is that the substrate is a Si / SiO2 substrate with graphene attached to its surface. Everything else is the same as in Example 2, and a similar iron (benzimidazole) polymer / graphene heterojunction can be obtained.

[0131] Example 2-3

[0132] The only difference from Example 2 is that the substrate is a Si / SiO2 substrate with hexagonal boron nitride attached to its surface. Everything else is the same as in Example 2, and a similar iron (benzimidazole) polymer / hexagonal boron nitride heterojunction can be obtained.

[0133] Example 3

[0134] 18 mg of benzimidazole and 280 mg of ferrocene (molar ratio 1:10) were respectively placed at both ends of a single-ended sealed inner tube, with a clean Si / SiO2 substrate placed between the benzimidazole and ferrocene. The inner tube was transferred to a dual-temperature zone tube furnace, with ferrocene and benzimidazole located in temperature zone 1 and temperature zone 2, respectively, and the substrate located in the growth region between the two temperature zones, where temperature zone 2 was upstream of the neon gas flow. Before growth, the system was evacuated, and then the furnace cavity was purged with helium; a helium flow rate of 2 sccm was maintained throughout the growth process. Temperature zones 1 and 2 were temperature-controlled, reaching 120°C in zone 1 and 400°C in zone 2, and held at these temperatures for 2 hours. The furnace cavity was then evacuated and cooled to obtain an iron (benzimidazole) polymer with the same structure.

[0135] The prepared iron (benzimidazole) polymer was subjected to optical microscopy and X-ray powder diffraction. Its morphology and crystal data are as follows: Figure 18 , Figure 19 As shown, the prepared iron (benzimidazole) polymer can be a single crystal or a polycrystalline film, both of which have high crystallinity.

[0136] Example 3-1

[0137] Compared to Example 3, the only difference is that the substrate is monocrystalline silicon. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0138] Example 3-2

[0139] The only difference from Example 3 is that the substrate is silicon nitride. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0140] Example 3-3

[0141] The only difference from Example 3 is that the substrate is sapphire. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0142] Examples 3-4

[0143] The only difference from Example 3 is that the substrate is mica. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0144] Examples 3-5

[0145] The only difference from Example 3 is that the substrate is quartz. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0146] Examples 3-6

[0147] The only difference from Example 3 is that the substrate is glass. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0148] Examples 3-7

[0149] The only difference from Example 3 is that the substrate is copper foil. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0150] Examples 3-8

[0151] The only difference from Example 3 is that the substrate is potassium bromide crystal. Everything else is the same as in Example 3, and an iron (benzimidazole) polymer with the same structure and similar effects can be obtained.

[0152] Example 4

[0153] 540 mg of benzimidazole and 28 mg of ferrocene (molar ratio 30:1) were respectively placed at both ends of a single-ended sealed inner tube. A Si / SiO2 substrate with N,N-dimethylformamide adhering to its surface was placed between the benzimidazole and ferrocene. The inner tube was transferred to a dual-temperature zone tube furnace, with ferrocene and benzimidazole located in temperature zone 1 and temperature zone 2, respectively. The substrate was located in the growth zone between the two temperature zones, with temperature zone 2 upstream of the neon gas flow. Before growth, the system was evacuated, and then the furnace cavity was purged with neon gas; a neon gas flow of 8 sccm was maintained throughout the growth process. The temperatures of temperature zones 1 and 2 were controlled, with temperature zone 1 reaching 200 °C and temperature zone 2 reaching 180 °C, and held at these temperatures for 5 hours. The furnace cavity was then evacuated and cooled to obtain an iron (benzimidazole) polymer with the same structure. The transverse size distribution of the iron (benzimidazole) polymer can reach 30 μm to 300 μm, and its thickness is 1 nm to 10 nm. The average roughness of the iron (benzimidazole) polymer is 0.413 nm.

[0154] Example 4-1

[0155] Compared to Example 4, the only difference is that the substrate is a Si / SiO2 substrate with diphenyl ether attached to its surface. Everything else is the same as in Example 4, and an iron (benzimidazole) polymer with the same structure can be obtained.

[0156] Example 4-2

[0157] Compared to Example 4, the only difference is that the substrate is a Si / SiO2 substrate with glycerol / benzyl alcohol attached to its surface. Everything else is the same as in Example 4, and an iron (benzimidazole) polymer with the same structure can be obtained.

[0158] Example 4-3

[0159] Compared to Example 4, the only difference is that the substrate is a Si / SiO2 substrate with glycerol / benzyl alcohol attached to its surface. Everything else is the same as in Example 4, and an iron (benzimidazole) polymer with the same structure can be obtained.

[0160] Example 5

[0161] 28 mg of ferrocene and 24 mg of 5-chlorobenzimidazole were placed at opposite ends of a single-ended sealed inner tube, with a clean Si / SiO2 substrate placed between the 5-chlorobenzimidazole and ferrocene. The inner tube was transferred to a dual-temperature zone tube furnace, with the ferrocene and 5-chlorobenzimidazole located in temperature zone 1 and temperature zone 2, respectively. The substrate was positioned in the growth zone between the two temperature zones, with temperature zone 2 located upstream of the krypton gas flow. Before growth, the system was evacuated, and the furnace cavity was then purged with krypton gas; a krypton gas flow rate of 2 sccm was maintained throughout the growth process. Temperature zones 1 and 2 were temperature-controlled, reaching 120°C in zone 1 and 400°C in zone 2, and held at these temperatures for 10 hours. The furnace cavity was then evacuated and cooled to obtain an iron (5-chlorobenzimidazole) polymer with a similar structure. The transverse size distribution of the iron (5-chlorobenzimidazole) polymer can reach 10 μm to 100 μm, and its thickness is 1 nm to 200 nm. The average roughness of the iron (5-chlorobenzimidazole) polymer is 0.342 nm.

[0162] Example 5-1

[0163] The only difference from Example 5 is that the second precursor is 5-methylbenzimidazole. Everything else is the same as in Example 5, and an iron (5-methylbenzimidazole) polymer with similar structure and effects can be obtained.

[0164] Example 5-2

[0165] The only difference from Example 5 is that the second precursor is 5-bromobenzimidazole. Everything else is the same as in Example 5, and an iron (5-bromobenzimidazole) polymer with similar structure and effects can be obtained.

[0166] Example 5-3

[0167] The only difference from Example 5 is that the second precursor is 5-aminobenzimidazole. Everything else is the same as in Example 5, and an iron (5-aminobenzimidazole) polymer with similar structure and effects can be obtained.

[0168] Example 6

[0169] 65 mg of bis(2,2,6,6,-tetramethyl-3,5-heptadecanoic acid) zinc and 18 mg of benzimidazole were placed at opposite ends of a single-ended sealed inner tube. A clean Si / SiO2 substrate was placed between the benzimidazole and the bis(2,2,6,6,-tetramethyl-3,5-heptadecanoic acid) zinc. The inner tube was transferred to a dual-zone tube furnace, with 5-chlorobenzimidazole and benzimidazole located in zones 1 and 2, respectively. The substrate was positioned in the growth zone between the two zones, with zone 2 upstream of the krypton gas flow. Before growth, the system was evacuated, and the furnace cavity was then purged with krypton gas. A krypton gas flow rate of 2 sccm was maintained throughout the growth process. The temperatures of zones 1 and 2 were controlled, with zone 1 reaching 150°C and zone 2 reaching 350°C, and held at these temperatures for 60 minutes. The furnace cavity was then evacuated and cooled to obtain a zinc (benzimidazole) polymer with a similar structure. The transverse size distribution of zinc (benzimidazole) polymers can reach 40 μm to 300 μm, and their thickness ranges from 1 nm to 30 nm. The average roughness of zinc (benzimidazole) polymers is 0.476 nm.

[0170] Example 6-1

[0171] The only difference from Example 6 is that the first precursor is bis(cyclopentadienyl)cobalt(II). Everything else is the same as in Example 6, and a cobalt (benzimidazole) polymer with similar structure and effects can be obtained.

[0172] Example 6-2

[0173] The only difference from Example 6 is that the first precursor is bis(tetramethylcyclopentadienyl)manganese(II). Everything else is the same as in Example 6, and a manganese (benzimidazole) polymer with similar structure and effects can be obtained.

[0174] Example 6-3

[0175] The only difference from Example 6 is that the first precursor is bis-(triphenylphosphine)nickel(II) chloride. Everything else is the same as in Example 6, and a nickel (benzimidazole) polymer with similar structure and effects can be obtained.

[0176] Comparative example:

[0177] Unlike the liquid-assisted chemical vapor deposition synthesis method used in this invention, the coordination polymer synthesis methods listed below produce thick bulk coordination polymers with a thickness of more than micrometers. The coordination polymers obtained have regular square or rectangular morphologies, and their average surface roughness is significantly greater than that of the coordination polymers provided in this invention. Furthermore, none of these synthesis methods can achieve the preparation of coordination polymer heterojunctions.

[0178] Comparative Example 1-1

[0179] 30 mg of ferrocene and 49 mg of benzimidazole were sealed in a layered quartz tube with a diameter of 4 mm. The mixture was heated at 250 °C for 3 days, followed by cooling, to obtain iron (benzimidazole) coordination polymer crystals. Under an optical microscope, the prepared iron (benzimidazole) coordination polymer was observed to be a uniformly square bulk; atomic force microscopy showed a thickness greater than 10 μm and an average roughness greater than 1 nm. This method cannot synthesize coordination polymer heterojunctions. The iron (benzimidazole) coordination polymer synthesized by this method does not possess gas-selective response capabilities.

[0180] Comparative Example 1-2

[0181] Solution A: 0.612 g ZnCl2 was dissolved in 23 mL of N,N-dimethylformamide and stirred for 20 minutes; Solution B: 0.354 g benzimidazole was dissolved in a mixture of 23 mL DMF and 0.22 g diethylamine and stirred for 20 minutes; Solution B was then added to Solution A and stirred. The reaction solution was then transferred to a high-pressure reactor and kept at 130 °C for 42 hours. The resulting white product was washed with methanol and dried in air to obtain a zinc (benzimidazole) coordination polymer. Under an optical microscope, the prepared zinc (benzimidazole) coordination polymer was observed to be a uniformly square or rectangular block; under an atomic force microscope, its thickness was greater than 15 μm and its average roughness was greater than 1.5 nm. This method cannot synthesize coordination polymer heterojunctions. The zinc (benzimidazole) coordination polymer synthesized by this method does not possess gas-selective response capabilities.

[0182] Comparative Examples 1-3

[0183] 1000 mL of DMF was added to a mixture of 3.025 g Zn(NO3)·6H2O and 7.695 g benzimidazole solids. The mixture was stirred for 1 hour, then allowed to stand at room temperature for 72 hours. ZIF-7 nanoparticles were obtained by centrifugation and washing the solids in the reaction solution with methanol. The wet product was dried overnight at 50 °C, and then dried in a vacuum oven at 120 °C for 48 hours. The obtained ZIF-7 nanocrystals were dispersed in distilled water at a concentration of 0.5 wt%, and then refluxed at 100 °C for 24 hours. The reaction solution was filtered, and the solid product was washed with distilled water and methanol, and then dried overnight at 50 °C to obtain a zinc (benzimidazole) coordination polymer. Under an optical microscope, the prepared zinc (benzimidazole) coordination polymer was observed to be a uniformly square bulk; under an atomic force microscope, its thickness was greater than 10 μm, and its average roughness was greater than 1.2 nm. This method cannot synthesize coordination polymer heterojunctions. The zinc (benzimidazole) coordination polymer synthesized by this method does not have the ability to respond selectively to gases.

[0184] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synthesizing a coordination polymer, characterized in that, The synthesis method is chemical vapor deposition, and the coordination polymer has a single crystal structure.

2. A method for synthesizing a coordination polymer, characterized in that, The synthesis method is liquid-assisted chemical vapor deposition.

3. The synthesis method according to claim 1 or 2, characterized in that, Coordination polymer single crystals were prepared by liquid-assisted chemical vapor deposition.

4. The synthesis method according to claim 3, characterized in that, The coordination polymer includes two-dimensional coordination polymer single crystals.

5. The synthesis method according to any one of claims 1-4, characterized in that, The following steps are involved: Step 1: Place the first precursor and the second precursor in the first temperature zone and the second temperature zone, respectively; Step 2: Heat the first and second temperature zones in the atmosphere to sublimate the first and second precursors into vapor, and maintain the temperature. Step 3: The vapors of the first precursor and the second precursor diffuse onto the growth substrate located in the growth region, and react in the liquid located on the substrate surface to obtain the coordination polymer; The growth zone is located in a temperature range where a temporary liquid phase environment can be formed.

6. The synthesis method according to claim 5, characterized in that, In step 3, the liquid is formed by an organic solvent adhering to the surface of the substrate, and / or by the self-condensation of the vapor of the first precursor or the vapor of the second precursor on the surface of the substrate.

7. The synthesis method according to claim 5, characterized in that, The coordination polymer includes a single-layer coordination polymer monocrystal.

8. The synthesis method according to claim 7, characterized in that, The coordination polymer comprises a metal M and a ligand X; The metal M includes at least one of iron, copper, zinc, molybdenum, cobalt, manganese, chromium, nickel, and tungsten; The ligand X includes at least one of benzimidazole, 5-methylbenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, and 5-aminobenzimidazole.

9. A single-crystal coordination polymer composite heterojunction, characterized in that, This includes coordination polymer single crystals and two-dimensional materials prepared by the synthesis method according to any one of claims 1-8; The two-dimensional material includes at least one of transition metal dichalcogenides, graphene, hexagonal boron nitride, and covalent organic frameworks.

10. A method for preparing a coordination polymer composite heterojunction, characterized in that, The following steps are involved: Step i: Place the first precursor and the second precursor in the first temperature zone and the second temperature zone, respectively; Step ii: Heat the first and second temperature zones in the atmosphere to sublimate the first and second precursors into vapor, and maintain the temperature; Step iii: The vapors of the first precursor and the second precursor diffuse into the substrate located in the growth region and whose surface is covered with a two-dimensional material, and react in the liquid located on the substrate surface to obtain a coordination polymer composite heterojunction; The growth zone is located in a temperature range where a temporary liquid phase environment can be formed.

11. The application of the coordination polymer prepared by the synthesis method according to any one of claims 1-8 and the coordination polymer composite heterojunction according to claim 9 in the fields of sensors and optoelectronics.

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