Method for controllably synthesizing metal-organic nanobelt

Abstract

The invention discloses a method for controllably synthesizing a metal-organic nanobelt, which comprises the following steps: sequentially depositing iron atoms and TCT molecules on the surface of clean Au (111) to obtain a metal substrate with the iron atoms and the TCT molecules; and the metal substrate is subjected to annealing treatment, and the heteromorphic C-Fe-N nanobelt structure is obtained. The metal-organic nanobelt is synthesized by introducing iron atoms to the surface and regulating and controlling the ratio of the iron atoms to organic molecules, and the product is single in structure and has high selectivity. The synthesized metal-organic nanobelt has C-Fe-N asymmetric bonding, and compared with a symmetric coordinate bond / organic metal covalent bond in the conventional metal-organic nanobelt, the metal-organic nanobelt has unique electromagnetic properties and has a wider application prospect in the interdisciplinary application aspects such as catalysis, information storage and sensors.

Description

Technical Field

[0001] The invention relates to a method for synthesizing a one-dimensional metal-organic nanobelt, and belongs to the technical field of material preparation. Background Art

[0002] The precise construction of relatively strong, well-defined and novel nanostructures on surfaces has attracted extensive attention due to its broad application prospects in the design and development of molecular devices. Metal atoms in metal-organic nanostructures can enrich the electromagnetic properties of organic systems, and thus show great application potential in multidisciplinary fields such as catalysis, information storage and sensors. In view of its potential application prospects, the selective construction of more complex metal-organic nanostructures has become a research hotspot.

[0003] Previously, most studies have focused on metal-organic nanostructures containing symmetric coordination bonds, such as di-, tri-, or tetra-coordinated N-metal-N coordination nanostructures or C-metal-C organometallic nanostructures. However, studies on asymmetric coordination metal-organic structures in which metal atoms are simultaneously bound to mixed ligands or even different functional groups are less common and remain challenging, which may enable the association of novel and unique properties of metal-organic systems. Therefore, the establishment of heterocoordinate metal-organic nanostructures may involve new chemical phenomena or properties and is of great research significance. To date, the synthesis of heterocoordinate nanostructures has been carried out in solution. The preparation of such structures by synthesis in solution generally has disadvantages such as low selectivity and is often accompanied by the generation of a large number of by-products. Summary of the invention

[0004] In order to solve the current problem of difficulty in heteroleptic synthesis, the purpose of the present invention is to provide a method for rationally selecting heteroleptic precursors and synthesizing heteroleptic C-Fe-N nanobelts by combining surface synthesis with surface coordination.

[0005] In order to solve the above technical problems, the present invention provides a method for synthesizing heteroleptic C-Fe-N nanobelts by surface coupling reaction, which specifically comprises the following steps:

[0006] Step 1: Iron atoms (Fe) and (cyanuric chloride) TCT molecules are sequentially deposited onto a clean Au (111) surface to obtain a metal substrate with iron atoms and (cyanuric chloride) TCT molecules;

[0007] Step 2: Annealing the metal substrate obtained in step 1 to obtain a heteroleptic C-Fe-N nanobelt structure. Further, in step 1, the clean Au (111) surface is obtained by cyclic argon etching-annealing treatment of the Au (111) surface.

[0008] Furthermore, the specific steps are as follows: the Au (111) metal single crystal substrate is introduced into the sample preparation chamber, the leak valve is slowly turned on, and argon gas is introduced into the chamber; when the gas pressure rises to 2.5×10 -5 mbar, adjust the argon etching parameters, set the argon ion energy to 1.5keV, and argon etching for 15 minutes; after the argon etching is completed, the substrate temperature is raised to 600K by the EBH-150 electron beam heating device to complete the high temperature annealing treatment; repeat the above argon etching-annealing operation 5 times to obtain a clean Au(111) surface. Further, in step 1, iron atoms are deposited by electron beam evaporation technology, and the fuse current and high voltage are controlled to be 4.5nA and 1.5kV respectively, and the deposition time is 10 minutes.

[0009] Furthermore, in step 1, OMBE organic molecule evaporation technology is used to deposit TCT molecules, and the deposition temperature is controlled to be 400K and the deposition time is 20 minutes.

[0010] Furthermore, in step 2, the annealing temperature is 500 K and the holding time is 15 minutes.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) The present invention synthesizes heteroleptic C-Fe-N nanobelts by a surface synthesis method. The preparation process is simple and controllable, avoiding the use of hazardous reagents, and the reaction rate of raw material molecules is higher, reducing waste.

[0013] (2) The synthesized heteroleptic C-Fe-N nanobelts are highly selective and have no by-products.

[0014] (3) As an important product of organic synthesis, the synthesized heteroleptic C-Fe-N nanobelts have great application potential in multidisciplinary fields such as catalysis, information storage and sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 (a) is a large-scale STM image of the metal substrate with Fe atoms and TCT molecules after annealing in Example 1 and the DFT optimization model of its enlarged image.

[0016] Figure 2 The large-size STM image (a), high-resolution STM image (b), and the overlap of the high-resolution STM image and its DFT-optimized gas phase structure model (c) of the metal substrate with TCT molecules in Comparative Example 1.

[0017] Figure 3 This is a large-scale STM scan image (30×30 nm) of the metal substrate with TCT molecules after annealing in Comparative Example 1.

[0018] Figure 4This is a large-scale STM scan image (50×50 nm) of the metal substrate with Fe atoms and TCT molecules after annealing in Comparative Example 2. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0020] The concept of the present invention is: after the organic molecules are deposited on the surface to form a self-assembled structure, sufficient energy is provided by heating, and the organic molecules are prompted to undergo chemical reactions under the catalytic action of the metal surface. Surface reactions are mainly stimulated by heating, but some surface reactions still cannot occur by heating alone. In this case, it is possible to consider introducing foreign metal atoms on the surface to promote surface reactions in the following two ways: on the one hand, foreign metal Fe atoms can act as catalysts to increase the reaction activity of the system; on the other hand, co-adsorbed foreign metal Fe atoms can form metal-organic coordination C-Fe-N nanobelt structures with organic molecules TCT molecules, which serve as templates for subsequent surface reactions.

[0021] The chemical reaction process of synthesizing heteroleptic C-Fe-N nanobelts by surface coupling reaction of the present invention is as follows:

[0022]

[0023] The invention discloses a method for synthesizing heteroleptic C-Fe-N nanobelts by surface coupling reaction, wherein (cyanuric chloride) TCT molecules undergo aldehyde dehydrogenation and intermolecular carbon-carbon coupling under the catalysis of Au (111) surface and Fe atoms to synthesize heteroleptic C-Fe-N nanobelts, and the method specifically comprises the following steps:

[0024] Step 1: Perform cyclic argon etching-annealing treatment on the Au(111) surface to obtain a clean Au(111) surface;

[0025] Step 2: First, electron beam evaporation technology is used to increase the fuse current and high voltage to 4.5nA and 1.5kV respectively, and Fe atoms are deposited on the clean Au(111) surface for 10 minutes to obtain a metal substrate with Fe atoms; then OMBE organic molecule evaporation technology is used to deposit TCT molecules on the surface of the metal substrate with Fe atoms, the deposition temperature is 400K, and the deposition time is 20 minutes to obtain a metal substrate with Fe atoms and TCT molecules;

[0026] Step 3: The metal substrate obtained in step 2 is annealed to 500 K and kept warm for 15 minutes, and then cooled naturally to obtain a metal substrate with heterogeneous C-Fe-N nanobelts.

[0027] Example 1

[0028] Step 1: Place the Au (111) metal single crystal substrate into the sample preparation chamber, slowly open the valve, and introduce argon gas into the chamber; wait until the gas pressure rises to 2.5×10 -5 mbar, adjust the argon etching parameters, set the argon ion energy to 1.5keV, and argon etching for 15 minutes. After the argon etching is completed, the substrate temperature is raised to 600K by the EBH-150 electron beam heating device to complete the high-temperature annealing treatment. Repeat the above argon etching-annealing operation 5 times to obtain a clean Au(111) surface.

[0029] Step 2: At room temperature, place the iron rod into the metal source, install the metal source into the fast injection chamber, and evacuate the chamber. Wait until the pressure in the chamber is less than 8×10 -8 mbar, using electron beam evaporation technology, the fuse current and high voltage were increased to 4.5nA and 1.5kV respectively, and the deposition time was controlled to be 10 minutes. Fe atoms were deposited on the clean Au(111) surface to obtain a metal substrate with Fe atoms. TCT molecules were loaded into a crucible, mounted on the molecular source, and then the molecular source was mounted on the fast injection chamber, and vacuum was drawn until the pressure in the chamber was less than 8×10 -8 mbar, OMBE organic molecule evaporation technology was used to raise the temperature to 400K, and the deposition time was controlled to be 20 minutes, and TCT molecules were deposited on the surface of the metal substrate with Fe atoms to obtain a metal substrate with Fe atoms and TCT molecules.

[0030] Step 3: The metal substrate with Fe atoms and TCT molecules is introduced into the sample preparation chamber, and the metal substrate is heated to 500K by an EBH-150 electron beam heating device and kept warm for 15 minutes, and then cooled naturally to obtain an annealed metal substrate with Fe atoms and TCT molecules.

[0031] The annealed metal substrate with Fe atoms and TCT molecules was introduced into the sample observation chamber and observed by STM. The formation of covalent oligomer structure was observed, mainly covalent dimer structure, which appeared as a one-dimensional chain structure in the STM scanning image (such as Figure 1 a), combined with DFT calculation, we can get its optimized model (such as Figure 1 b). These covalent oligomers are formed by dehalogenation of a C-Cl group in the TCT molecule to form covalent dimers; a C-Cl group in the covalent dimer undergoes dehalogenation, and the dehalogenated covalent dimers are interconnected through C-Fe-N bonds to form a mixed metal-organic hybrid.

[0032] Comparative Example 1

[0033] Step 1: Same as step 1 in Example 1.

[0034] Step 2: At room temperature, place TCT molecules into a crucible, install it on the molecular source, then install the molecular source into the rapid injection chamber, and evacuate the chamber until the pressure in the chamber is less than 8×10 -8 mbar, using OMBE organic molecule evaporation technology, the temperature was raised to 400K, the deposition time was controlled to be 20 minutes, and TCT molecules were deposited on the clean Au(111) surface to obtain a metal substrate with TCT molecules. The metal substrate with TCT molecules was introduced into the sample observation chamber and observed by STM. The large-size STM image and high-resolution STM image are shown as follows: Figure 2 As shown in a and b in Figure 1, the self-assembled structure of TCT molecules can be observed. The DFT optimized model is superimposed on the high-resolution image as shown in Figure c.

[0035] Step 3: Place the metal substrate with TCT molecules into the sample preparation chamber, heat the metal substrate to 500K using an EBH-150 electron beam heating device and keep it warm for 15 minutes, then cool it naturally to obtain an annealed metal substrate. Place the metal substrate into the sample observation chamber and observe it using STM, such as Figure 3 As shown, desorption can be observed at 500 K and no reaction occurs.

[0036] Comparative Example 2

[0037] The other processes are the same as those in Example 1, except that in step (2), the deposition time of TCT molecules is changed to 10 minutes.

[0038] The annealed metal substrate with Fe atoms and TCT molecules is introduced into the sample observation chamber and observed using STM. Figure 4 As shown, since the deposition time of TCT molecules is shortened, resulting in a decrease in their surface coverage, it can be observed that the surface coverage of the product after the surface coupling reaction is reduced compared with Example 1. Compared with Example 1, the deposition time of TCT molecules and Fe atoms in Comparative Example 2 is shortened.

Claims

1. A method for synthesizing heteroleptic C-Fe-N nanobelts by surface coupling reaction, characterized in that: The specific steps include: Step 1: Iron atoms and TCT molecules are sequentially deposited onto a clean Au(111) surface to obtain a metal substrate with iron atoms and TCT molecules; Step 2: Annealing the metal substrate obtained in step 1 to obtain a heterogeneous C-Fe-N nanobelt structure.

2. The method according to claim 1, characterized in that In step 1, the clean Au (111) surface is obtained by performing a cyclic argon etching-annealing treatment on the Au (111) surface.

3. The method according to claim 2, characterized in that The specific steps are as follows: insert the Au (111) metal single crystal substrate into the sample preparation chamber, slowly open the leak valve, and introduce argon gas into the chamber; When the pressure rises to 2.5×10 -5 mbar, adjust the argon etching parameters, set the argon ion energy to 1.5 keV, and argon etching for 15 minutes; after the argon etching is completed, the substrate temperature is raised to 600 K by an EBH-150 electron beam heating device to complete the high-temperature annealing treatment; repeat the above argon etching-annealing operation 5 times to obtain a clean Au(111) surface.

4. The method according to claim 1, characterized in that In step 1, electron beam evaporation technology is used to deposit iron atoms, the fuse current and high voltage are controlled to be 4.5 nA and 1.5 kV respectively, and the deposition time is 10 minutes.

5. The method according to claim 1, characterized in that In step 1, the TCT molecules were deposited using the OMBE organic molecule evaporation technique, with the deposition temperature controlled at 400 K and the deposition time at 20 min.

6. The method according to claim 1, characterized in that In step 2, the annealing temperature is 500 K and the holding time is 15 minutes.

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