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CN-121975142-A - Method for directly growing highly oriented metal organic framework film by liquid-gas phase reaction

CN121975142ACN 121975142 ACN121975142 ACN 121975142ACN-121975142-A

Abstract

The application discloses a method for directly growing a highly oriented metal organic frame film by utilizing a liquid-gas phase reaction, which utilizes direct chemical reaction of solvated metal ions on the surface of a substrate and organic ligands in gas phase at a liquid-gas interface, and is different from the traditional solid-gas reaction (such as ALD or CVD), wherein an LVD process directly utilizes metal ions dissolved in a water phase, an ultrathin water layer is used as a carrier, continuous supply and uniform distribution of the metal ions at a reaction interface are ensured by the fluidity of the liquid phase, so as to support a continuous nucleation process, and methanol is introduced into a reaction system as a structure guiding agent in the film forming process depending on the accurate balance between the reaction temperature and the water evaporation rate and the ligand vapor consumption dynamics. The methanol molecules have stronger interactions with the (112) crystal face of KAUST-7 crystals, stabilize the surface by the "solvent-capping effect" produced, and inhibit the growth of the crystals in the direction perpendicular to that face, thereby inducing the crystals to form a high degree of (112) preferential orientation on the substrate surface.

Inventors

  • LIU YUTAO
  • Shen Yule
  • LAN TIANHAO
  • LI LIBO

Assignees

  • 太原理工大学

Dates

Publication Date
20260505
Application Date
20260320

Claims (10)

  1. 1. A method for directly growing a highly oriented metal organic framework film by utilizing a liquid-gas phase reaction is characterized in that the method is to directly grow a continuous MOF film with oriented crystal face orientation, such as (112) oriented crystal face and (002) oriented crystal face, on a porous substrate by a liquid-gas deposition process, wherein the core of the process is to carry out interface reaction between a solvated metal ion liquid layer reserved on the surface of the substrate and ligand molecules in a gas phase, and the water evaporation and crystal nucleation growth process can be accurately balanced by adjusting the ambient temperature and the precursor concentration, so that random orientation is avoided, and crystals are induced to be arranged in a specific direction.
  2. 2. A method for directly growing highly oriented metalorganic framework films utilizing liquid-vapor phase reactions according to claim 1, characterized in that the method comprises interfacial liquid layer build-up, vapor phase ligand reaction and synergistic regulatory growth steps; The interface liquid layer is constructed by immersing a porous substrate in a precursor aqueous solution containing a metal source, and retaining a liquid interface layer containing saturated metal ions on the surface of the substrate and in the pores after taking out the porous substrate; the gas phase ligand reaction is to put a substrate with a liquid interface layer into a reactor containing organic ligand vapor and structure directing agent vapor; The synergistic regulation and control growth is to directly induce MOF crystals to grow along a specific crystal direction at a liquid-gas interface by controlling the reaction temperature so as to balance the liquid layer water evaporation rate and the ligand diffusion consumption rate, so that a continuous compact oriented film is formed.
  3. 3. A method for directly growing highly oriented metal-organic framework films by liquid-gas phase reaction according to claim 1, The mixed vapor of gas ligand reaction is generated by the volatilization of liquid pyrazine-methanol mixture under the closed environment, and the structure directing agent generates a solvent end-capping effect through the strong interaction with a specific crystal face, thereby dynamically inhibiting the vertical growth of the crystal face.
  4. 4. A method for directly growing a highly oriented metal organic framework film by liquid-gas phase reaction according to any of claims 1-2, wherein the metal source is selected from the group consisting of salts containing fluorinated metal anions, niNbOF5, the organic ligand is pyrazine, the structure directing agent is a polar alcohol, the polar alcohol is methanol, and the porous substrate is an α -Al2O3 ceramic substrate when the MOF film is KAUST-7 film, i.e., nbOFFIVE-1-Ni.
  5. 5. A method for directly growing highly oriented metal-organic framework films by liquid-gas phase reaction according to claim 3, When the MOF film is KAUST-7 films, the concentration of the precursor aqueous solution in the interface liquid layer construction is 0.01 g/mL to-0.03 g/mL, and the mass ratio of the organic ligand to the structure directing agent is 1:1.5-1.7.
  6. 6. A method for directly growing highly oriented metal-organic framework films by liquid-gas phase reaction according to claim 3, characterized in that the reaction temperature of the method is 60 ℃ to 80 ℃ and is kept static for 24 hours in a 60 ℃ environment.
  7. 7. A method for directly growing a highly oriented metal organic framework film by liquid-vapor phase reaction according to claim 3, wherein in the preparation of KAUST-7 films, the methanol vapor is preferentially adsorbed on (112) crystal planes to induce formation of highly (112) oriented ultrathin films, and the film thickness of the prepared MOFs is controlled to be 200-500 nm.
  8. 8. A method for directly growing a highly oriented metal-organic framework film by liquid-gas phase reaction according to claim 3, wherein the method is carried out in such a manner that a highly (002) film can be obtained when an oriented Zn2 (bim) 4 film or a (Co/Zn) 2 (bim) 4 film is prepared by changing a metal source and a structure directing agent.
  9. 9. A method for directly growing highly oriented metal-organic framework films by liquid-gas phase reaction according to claim 7, When the Zn2 (bim) 4 film is oriented, the metal source is zinc nitrate, the organic ligand is pyrazine, the structure directing agent is ethanol, the mass ratio of the organic ligand to the structure directing agent is 1:1.25-1.5, the reaction temperature is 165-180 ℃, and the reaction time is 10-16 hours.
  10. 10. The method for directly growing a highly oriented metal-organic framework film by liquid-gas phase reaction according to claim 7, wherein a (Co/Zn) 2 (bim) 4 film is prepared, the oriented metal source is zinc nitrate, the organic ligand is pyrazine, the structure directing agent is ethanol or methanol, the mass ratio of the organic ligand to the structure directing agent of the highly (002) oriented film is 1:1.25-1.5, and the highly (002) oriented film can be obtained. The reaction temperature is 165-180 ℃ and the reaction time is 10-16 hours.

Description

Method for directly growing highly oriented metal organic framework film by liquid-gas phase reaction Technical Field The invention belongs to the technical field of nano material preparation and membrane separation, and particularly relates to a method for directly growing a highly oriented metal organic framework membrane by utilizing liquid-gas phase reaction. Technical Field The metal organic frame film (MOF film) is used as a film form of the MOFs material, so that the porous characteristic of the MOFs can be combined with the continuity and the easy integration of the film, the limitation that the MOF powder material is difficult to directly apply to device integration is broken through, the application scene of the MOFs material is further expanded, and the MOFs material becomes one of research hotspots in the current material science field. The performance of the MOF film is closely related to the crystal orientation of the MOF film, the highly oriented MOF film can realize the directional arrangement of crystal pore channels, effectively reduce the grain boundary defects in the film, and remarkably improve the selectivity, permeability and stability of the MOF film in the applications of gas separation, catalysis and the like, so that the preparation of the highly oriented MOF film is one of the key preconditions for realizing the industrial application of the MOF film. Currently, the main preparation methods of MOF films include in-situ solvothermal synthesis, secondary growth, electrochemical deposition, layer-by-layer self-assembly, vapor deposition, vapor-phase assisted synthesis, and the like. Among them, the in-situ solvothermal synthesis method is one of the most commonly used methods, and the method is to soak a substrate in a mixed solution containing metal ions and organic ligands, and react under high temperature and high pressure conditions to make MOF crystals grow in-situ on the surface of the substrate to form a film. The method has the obvious defects that the reaction system is in a homogeneous liquid phase environment, the nucleation and growth directions of MOF crystals are difficult to control, irregularly oriented polycrystalline films are easy to form, the grain boundary defects are more, meanwhile, the reaction time is long, usually tens of hours or even days are required, the preparation efficiency is low, the requirements on equipment are high under the condition of high temperature and high pressure, the preparation cost is increased, and the large-scale production is not facilitated. The secondary growth method is the most commonly used preparation method, through loading MOF seed crystal on the surface of the substrate first, then carrying out secondary growth to form a continuous film, although the orientation of the film can be improved to a certain extent, the method has complicated steps, the preparation and loading processes of the seed crystal need to be accurately controlled, the operation difficulty is high, and the problem of unsound combination between the seed crystal and the substrate, between the seed crystal and the MOF film which grows subsequently easily occurs, so that the mechanical stability of the film is poor, the rigorous requirements in practical application are difficult to meet, meanwhile, the whole preparation period is still longer, the production efficiency is limited, and the method involves depositing an orientation seed crystal layer on the substrate in advance, and then carrying out epitaxial growth. The electrochemical deposition method can be carried out at normal temperature and normal pressure, can accurately control the film growth thickness, is suitable for preparing the MOF film on the conductive substrate, but the method has higher requirements on equipment, can possibly introduce impurities to influence the film performance, is difficult to realize highly oriented crystal growth, is only suitable for preparing the MOF film of a specific type, has poor universality, and cannot meet the preparation requirements of oriented films of various MOF systems. As CN 119701652A discloses a high-stability MOF film and preparation and gas-liquid separation application thereof, firstly, a compact MIL-140s seed crystal layer is deposited on a porous carrier, then, the film is placed in precursor liquid containing a metal source and an organic ligand, after a certain period of thermodynamic growth, gaps between the seed crystal layers are gradually closed through coordination reaction of the metal source and the organic ligand, and finally, a continuous and good continuous MIL-140s film layer is formed, and gas (liquid) separation tests show that the MIL-140s film has excellent gas-liquid separation performance. The micro-mesoscopic structure (such as crystal orientation, film layer thickness, inter-crystal defects and the like) of the MIL-140s film can be obviously regulated and optimized by changing the thermodynamic growth temperature, so that