Preparation method for realizing surface epitaxial growth of metal organic framework by matching two-dimensional material template with lattice symmetry
阅读说明：本技术 通过晶格对称性匹配二维材料模板实现金属有机框架表面外延生长的制备方法 (Preparation method for realizing surface epitaxial growth of metal organic framework by matching two-dimensional material template with lattice symmetry ) 是由 孙正宗 胡安琪 于 2019-09-04 设计创作，主要内容包括：本发明涉及一种通过晶格对称性匹配二维材料模板实现金属有机框架表面外延生长的制备方法。采用化学气相沉积法,在铜箔上生长出石墨烯,或采用液相剥离法制备石墨烯；以所得的石墨烯为模板,采用溶剂热法,在石墨烯表面外延生长出金属有机框架材料；所述模板基底还可以是其它二维材料(如硫化钼)。要求二维模板材料和二维金属有机框架具有匹配的晶格对称性,符合外延生长的重合位置点阵匹配理论。通过本方法得到的金属有机框架薄膜具有高度的晶面选择性,以及与模板耦合作用强的综合性能。本方法分步控制,操作简单,可根据性能要求更改外延生长模板材料,并可以在不同种类金属有机框架上拓展,可以精确构造符合需求的金属有机框架复合材料。(The invention relates to a preparation method for realizing the epitaxial growth of the surface of a metal organic framework by matching a two-dimensional material template with lattice symmetry. Growing graphene on the copper foil by adopting a chemical vapor deposition method, or preparing the graphene by adopting a liquid phase stripping method; epitaxially growing a metal organic framework material on the surface of the graphene by using the obtained graphene as a template and adopting a solvothermal method; the template substrate may also be another two-dimensional material (e.g., molybdenum sulfide). The two-dimensional template material and the two-dimensional metal organic framework are required to have matched lattice symmetry and accord with the coincident position lattice matching theory of epitaxial growth. The metal organic framework film obtained by the method has high crystal face selectivity and strong comprehensive performance of coupling with a template. The method is controlled step by step, is simple to operate, can change the epitaxial growth template material according to the performance requirement, can be expanded on different types of metal organic frames, and can accurately construct the metal organic frame composite material meeting the requirements.)
1. A preparation method for realizing the surface epitaxial growth of a metal organic framework by matching a two-dimensional material template with lattice symmetry is characterized by comprising the following specific operation steps:
the method comprises the steps of taking an electrochemically polished copper foil as a growth substrate, adopting a chemical vapor deposition method, taking methane and hydrogen as gas sources, growing graphene single crystals or graphene films on two surfaces of the copper foil at high temperature, or adopting a liquid phase stripping method to strip graphite to obtain graphene nanosheets, taking the graphene single crystals, the graphene films or the graphene nanosheets as templates, adding the graphene single crystals, the graphene films or the graphene nanosheets templates into a precursor solution by adopting a solvothermal method, and epitaxially growing an organic metal framework on the surfaces of the templates by using the precursor in the precursor solution.
2. The method of claim 1, wherein the copper foil has a thickness of 10 to 30 μm.
3. The method according to claim 1, wherein the electrochemical polishing is carried out under a controlled current condition of 1-3A for 1-3 min, and the electrolytic solution is H in a volume ratio of 3:13PO4:H2O。
4. The preparation method according to claim 1, wherein the conditions for growing the graphene single crystal by the chemical vapor deposition method are as follows: the temperature is 1050 ℃, the hydrogen flow is 500 sccm, the methane concentration is 1% (the carrier gas is argon), the methane flow is 70-90 sccm, and the pressure is 3000-6000 Pa; graphene single crystals with different crystal axis sizes can be obtained by adjusting growth conditions (such as time, pressure and the like).
5. The preparation method according to claim 1, wherein the solution used in the liquid phase stripping method is a precursor solution used in the synthesis of the organic metal framework, the apparatus used in the liquid phase stripping method is an ultrasonic cleaning machine, the ultrasonic power is 100-120W, and the ultrasonic time is 6-8 h.
6. The method according to claim 1, wherein the concentration of the precursor used in the precursor solution added to the template is 1/1000-1/1; different types (such as FDM-23 and MOF-74) of metal-organic frameworks with different thicknesses and sizes can be prepared by changing the concentration of the template and the feeding ratio of the precursors and controlling the growth time.
7. The method of claim 1, wherein the lattice symmetry of the template material matches the lattice symmetry of one of the crystal planes of the metal-organic framework, and the epitaxial growth of the metal-organic framework on the template conforms to the coincident position lattice matching theory (CSL).
8. The method of claim 7, wherein the template material used to grow the two-dimensional metal-organic framework is not modified with precursor functional groups.
9. The preparation method according to claims 1 to 8, characterized in that the metal organic framework thin film obtained by the preparation method has stronger crystal face selectivity (single crystal also has higher plane/thickness ratio) and comprehensive performance which is complementary with the template; other kinds of metal organic frameworks can be epitaxially grown on the surface of different templates (such as molybdenum sulfide) by using a solvothermal method.
Technical Field
The invention belongs to the technical field of new material preparation, and particularly relates to a preparation method for realizing the epitaxial growth of the surface of a Metal Organic Framework (MOFs) by matching a two-dimensional material template through lattice symmetry.
Background
The metal-organic framework Materials (MOFs) have adjustable pore diameters and rich active centers, and can perform specific interaction with guest molecules, so that the MOFs are considered to be catalytic materials with a great application prospect. MOFs have achieved many applications and developments from gas separation to heterogeneous catalysis. The MOF is applied to the field of electrochemistry, so that the types of electrochemical catalysts and electrochemical devices can be greatly enriched, and the application field of the MOF is widened. However, most MOFs are intrinsically insulating, non-conducting, which limits their performance in electrocatalytic applications. Although some conductive MOFs can be synthesized in the laboratory, their number is limited, and the molecular structure design is difficult and difficult to popularize on a large scale. Therefore, how to retain the crystal advantages of the MOF to the maximum extent while improving the electrical properties of the MOF has a very important significance for revealing the intrinsic electrocatalytic properties of the MOF.
Nanomaterials often exhibit new physical, chemical properties that differ from their three-dimensional (3D) bulk structure. For example, hexagonal boron nitride, a typical insulating van der waals layered material, can allow electron tunneling when its thickness is reduced to a single or a few atomic layers. Unlike graphite, graphene has excellent mechanical, electrical, optical and other physical properties, and has become a star material in the scientific research field in recent years, so that revolution and hot tide in the two-dimensional material field are initiated and promoted. Similarly, many MOFs have a layered structure that can be engineered into two-dimensional (2D) nanostructures while retaining the advantages of high crystallinity and large specific surface area. The common method for preparing the two-dimensional metal organic framework comprises the steps of growing the two-dimensional metal organic framework from bottom to top by using a high polymer or an oxide as a template, and stripping the layered block metal organic framework from top to bottom by a liquid phase stripping method to obtain the two-dimensional metal organic framework.
Epitaxial growth is commonly used for material preparation in the field of high-precision electronic devices and is characterized by growing a new single-crystal layer with lattice and symmetry matching on a single-crystal substrate (base) to achieve optimal physical and chemical coupling in the epitaxial heterostructure. In recent years, many two-dimensional materials such as transition metal compounds have been reported as two-dimensional materials of epitaxial layers and van der waals heterojunction structures thereof by epitaxial templating. Epitaxial growth of MOFs on conducting or metallic phase two-dimensional materials would likely improve the overall electrochemical performance of MOFs. Up to now, the epitaxial growth of high-plane orientation 2D MOFs on unmodified graphene templates has not been achieved.
Disclosure of Invention
The invention aims to provide a preparation method for realizing the surface epitaxial growth of Metal Organic Frameworks (MOFs) by matching a two-dimensional material template through lattice symmetry aiming at the problems in the prior art. The metal organic framework film obtained by the method has stronger crystal face selectivity (the single crystal also has higher plane/thickness ratio) and comprehensive performance which is complementary with the template. The preparation method is controlled step by step, is simple to operate, and can be expanded on different templates (such as molybdenum sulfide) and different metal organic frameworks by using the traditional solvothermal method.
The invention provides a preparation method for realizing the epitaxial growth of the surface of a metal organic framework by matching a two-dimensional material template with lattice symmetry, which comprises the following specific operation steps:
the method comprises the steps of taking an electrochemically polished copper foil as a growth substrate, adopting a chemical vapor deposition method, taking methane and hydrogen as gas sources, growing graphene single crystals or graphene films on two surfaces of the copper foil at high temperature, or adopting a liquid phase stripping method to strip graphite to obtain graphene nanosheets, taking the graphene single crystals, the graphene films or the graphene nanosheets as templates, adding the graphene single crystals, the graphene films or the graphene nanosheets templates into a precursor solution by adopting a solvothermal method, and epitaxially growing an organic metal framework on the surfaces of the templates by using the precursor in the precursor solution.
In the invention, the thickness of the copper foil is 10-30 μm.
In the invention, the electrochemical polishing controls the current condition to be 1-3A and the time to be 1-3 min, and the electrolytic solution adopts H with the volume ratio of 3:13PO4:H2O。
In the invention, the conditions for growing the graphene single crystal by adopting the chemical vapor deposition method are as follows: the temperature is 1050 ℃, the hydrogen flow is 500 sccm, the methane concentration is 1% (the carrier gas is argon), the methane flow is 70-90 sccm, and the pressure is 3000-6000 Pa; graphene single crystals with different crystal axis sizes can be obtained by adjusting growth conditions (such as time, pressure and the like).
In the invention, the solution used in the liquid phase stripping method is a precursor solution used in the synthesis of the organic metal framework, the instrument used in the liquid phase stripping is an ultrasonic cleaning machine, the ultrasonic power is 100-120W, and the ultrasonic time is 6-8 h.
In the invention, the concentration of the precursor used in the precursor liquid added into the template is 1/1000-1/1 of the corresponding concentration when synthesizing the massive metal-organic framework without the template; different types (such as FDM-23, MOF-74 and the like), thicknesses and sizes of metal-organic frameworks can be prepared by changing the concentration of the template and the feeding ratio of the precursors and controlling the growth time.
In the invention, the lattice symmetry of the template material is matched with the lattice symmetry of one crystal face of the metal organic framework, and the epitaxial growth of the metal organic framework on the template conforms to the coincidence position lattice matching theory (CSL).
In the present invention, the template material used to grow the two-dimensional metal-organic framework does not require modification of the precursor functional groups.
In the invention, the metal organic framework film obtained by the preparation method has stronger crystal face selectivity (single crystal also has higher plane/thickness ratio) and comprehensive performance which is complementary with a template; other kinds of metal organic frameworks can be epitaxially grown on the surface of different templates (such as molybdenum sulfide) by using a solvothermal method.
In the invention, the two-dimensional metal organic framework grown by the epitaxial template method is characterized and analyzed by methods such as an optical microscope, a Scanning Electron Microscope (SEM), a Raman spectrum (Raman), a Transmission Electron Microscope (TEM), an X-ray crystal diffraction (XRD), an Atomic Force Microscope (AFM) and the like.
Compared with the prior art, the invention has the beneficial effects that: (1) two-dimensional material templates with matched lattice symmetry, particularly graphene conductive templates, can be used for epitaxial growth of an insulated metal organic framework, so that the electrochemical performance of the insulated metal organic framework is greatly improved; (2) the two-dimensional material template is prepared by adopting a simple and easy chemical vapor deposition technology and a liquid phase stripping method, is suitable for large-scale preparation, and has rich types of selectable templates; (3) the two-dimensional metal organic framework is synthesized by adopting a solvothermal method, the operation is simple, and the types of the selectable metal organic frameworks are rich. (4) The two-dimensional metal organic framework grown by the epitaxial template method has higher crystal face selectivity (single crystal also has higher plane/thickness ratio). The novel preparation technology of the two-dimensional metal organic framework has certain significance for expanding the application range of the two-dimensional metal organic framework.
Drawings
Fig. 1 is a representation of the process of epitaxially growing a metal-organic framework on a graphene template surface and its product. Wherein, (a) a schematic diagram of a process for epitaxially growing a metal organic framework on the surface of a graphene template; (b) taking a picture of a two-dimensional metal organic framework single crystal obtained by liquid-phase stripped graphene template epitaxial growth under a TEM; (c) a TEM electronic selective area diffraction superposition graph of the two-dimensional metal organic framework single crystal at A, B, C three positions in (b) and the crystal face of the two-dimensional metal organic framework single crystal are calibrated; (d) marking lattice stripes and crystal faces of the two-dimensional metal organic framework single crystal under a high-resolution TEM; (e) and transferring the graphene grown on the copper foil by the chemical vapor deposition method to a TEMgrid to be used as a template, and carrying out epitaxial growth to obtain a TEM (transmission electron microscope) picture of the metal organic framework crystal on the surface of the graphene.
Fig. 2 is a related structural representation of a two-dimensional organic metal framework single crystal obtained by epitaxial growth using a graphene nanosheet prepared by a liquid phase lift-off method as a template. The graphene nanosheet prepared by the liquid phase stripping method is used as a template to carry out epitaxial growth to obtain a large-size single crystal optical lens photo of a two-dimensional organic metal framework single crystal at a level of 20 microns; (b) determining the position of a graphene template in the two-dimensional organic metal framework single crystal by the red frame region in the Raman mapping (a); (c) raman spectrum characteristic peaks of the graphene template position and other positions in Raman mapping; (d) AFM thickness and surface topography analysis of a typical two-dimensional organometallic framework single crystal; (e) analyzing the AFM thickness statistical distribution of the two-dimensional organic metal framework single crystal; (f) XRD contrast analysis of two-dimensional organic metal framework single crystals and bulk metal organic framework crystals synthesized by the two-dimensional organic metal framework single crystals without graphene templates.
Fig. 3 is a correlation electrochemical performance analysis of a two-dimensional organic metal framework single crystal obtained by epitaxial growth using a graphene nanosheet prepared by a liquid phase lift-off method as a template. The electrochemical Hydrogen Evolution Reaction (HER) catalytic performance characterization method comprises the following steps of (a) characterizing the electrochemical Hydrogen Evolution Reaction (HER) of a two-dimensional organic metal framework single crystal and a metal organic framework crystal which is not synthesized by a graphene template; (b) the Tafel slope of the two is characterized; (c) hydrogen conversion frequency (TOC) characterization of both; (d) the electrochemical active area of the two is characterized; (e) charge transfer resistance characterization of both.
Fig. 4 is an epitaxial growth of a metal organic framework on other template substrates. Wherein, (a) a graphene single crystal photo mirror photo grown on a copper foil by a chemical vapor deposition method; (b) a photo-mirror photograph of the metal-organic frame after the graphene single crystal surface is epitaxially grown; (c) characterizing Raman spectrum characteristic peaks of graphene before and after a metal organic framework is epitaxially grown on the copper foil by using a graphene single crystal grown on the copper foil by a chemical vapor deposition method; (d) AFM (atomic force microscopy) morphology picture and thickness measurement of the molybdenum disulfide single crystal grown on the silicon oxide wafer by the chemical vapor deposition method; (e) AFM appearance photos and thickness measurement of the metal organic frame after the molybdenum disulfide single crystal surface is epitaxially grown; (f) and characterizing Raman spectrum characteristic peaks before and after the molybdenum sulfide single crystal grown on the silicon oxide wafer by a chemical vapor deposition method is epitaxially grown on the metal organic framework.
Detailed Description
The invention is further elucidated with reference to the drawing.