CN1333113C - Highly oriented laminated dihydroxy composite metal oxide film and its preparing method - Google Patents

Abstract

The present invention relates to a highly oriented layer-shaped dihydroxy composite metal oxide (LDHs) film and a biomimetic synthesis method thereof. An LDHs film prepared by the present invention is grown on a high molecular base material. The chemical general formula of the LDHs film is [M<1-x><2+>M<x><3+>(OH)<2>]<x+>(CO<3><2->)<x/2>. yH<2>O. The crystal face (001) (or face ab) of the LDHs film is perpendicular to the surface of a subtract, the film is highly oriented and compact, and the film thickness is from 0.5 to 5 micrometers. The biomimetic synthesis method comprises the steps that a high molecular material substrate with surface sulfonation of the film is horizontally suspended in a solution containing urea and a corresponding metal salt; the purpose of controlling anion release is reached by controlling urea decomposition speed through controlling reaction temperature and time; LDHs nucleates and grows in an oriented mode on the substrate to obtain the highly oriented and compact LDHs film of which the crystal face (001)is perpendicular to the surface of the substrate, and the thickness of the obtained LDHs film is from 0.5 to 5 micrometers. The present invention solves the problems that the LDHs film can only be prepared by deposition on an inorganic substrate in the existing method, and the directionality of LDHs crystals in the film is poor.

Description

Highly oriented layered double hydroxyl compound metal oxide film and its preparation method

technical field

The invention relates to a highly oriented layered double hydroxyl compound metal oxide film and a preparation method thereof, in particular to a biomimetic synthesis method of a layered double hydroxyl compound metal oxide film grown on a surface sulfonated polymer material substrate.

Background technique

Oriented calcium carbonate films, goethite (α-FeOOH) films and titanium dioxide films have been successfully synthesized on surface sulfonated polystyrene substrates (Science, 1994, 264:48). Due to the similarity to the biomineralization of inorganic substances in living organisms, the method is called biomimetic synthesis.

Layered double hydroxyl complex metal oxides, also called hydrotalcite-like (LDHs), are an important class of inorganic functional materials. Because of its layered structure, adjustable variability of laminate elements and exchangeability of anions between layers, it has a wide range of applications, such as electrochemical biosensors, humidity sensors, ion-selective electrodes, electrode modification, biomimetic Catalysts, photochromic materials, magnetic material precursors, and shape-selective separation materials for mixtures are currently attracting attention in academic and industrial research. After many inorganic materials are made into oriented thin films, their functionalities, such as the anisotropy and directional catalytic performance of optical, electrical, and magnetic functions, will be significantly improved. If the oriented LDHs thin film is obtained, the above-mentioned functions of LDHs can obviously be improved, which will lay a good foundation for its application in optical, electrical and magnetic devices and directional catalysis. Most layered substances are structurally anisotropic and can be unfolded into films for use as functionalized coatings or separators, however, unlike other layered materials, LDHs are not easily cast into thin films and their crystallinity is more difficult to control The orientation in thin films hinders the application development and deviceization of LDHs materials in this field.

In the document Adv.Mater., 2001,13(16):1263, E.Gandner et al. deposited the colloidal solution of LDHs on glass to obtain an alkoxy-intercalated magnesium-aluminum LDHs film. The preparation method was complicated, and the obtained The thickness of the film is more than 30 μm, the film is formed by the accumulation of LDHs powder, and there are LDHs aggregates in the film, which inevitably has defects such as uneven surface of the film and loose combination with the matrix.

In Langmuir, 2002, 18(5): 1580, J.X.He and others deposited the magnesium aluminum carbonate LDHs obtained from the Langmir-Blodgett film on the mica sheet to obtain the LDHs film. The preparation method is also complicated, and the orientation of the film is very poor. , the surface is very rough, easy to peel off into powder.

In the literature Chem.Commun., 2003: 2740 and Langmuir, 1998, 14 (10): 2890, J.H.Lee and K.Yao etc. deposited LDHs crystals in aqueous solution on highly oriented pyrolytic graphite and silicon (100 ) on the wafer, although it has a certain orientation, the LDHs are discontinuous, have low density, and are not tightly combined with the substrate, so the practicability is not high.

The methods used in the above literatures are to deposit LDHs on the inorganic substrate. However, it is difficult to separate the thin film from the inorganic substrate, and it is difficult to separately display the functionality of the LDHs thin film. The organic matrix can be removed by simple methods such as dissolving organic solvents or oxidative decomposition to obtain unsupported LDHs films.

Contents of the invention

The purpose of the present invention is to provide a highly oriented layered bishydroxy complex metal oxide film on an organic substrate. Another object of the present invention is to provide a method for preparing a highly oriented LDHs film, that is, a method for bionically synthesizing a highly oriented LDHs film on a surface sulfonated polymer material substrate to prepare a LDHs film with high orientation and density. Realize the deviceization of multifunctional material LDHs.

The highly oriented layered double hydroxyl compound metal oxide film provided by the present invention is an LDHs film grown on a polymer material, and the general chemical formula of the film layer LDHs is:

[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ (CO ₃ ^2- ) _x/2 ·yH ₂ O),

Where M ²⁺ represents any one of divalent metal ions Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ , preferably Mg ²⁺ or Ni ²⁺ ; M ³⁺ represents Any of trivalent metal ions Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ , preferably Al ³⁺ ; 0.2≤x≤0.4 , 0≤y≤2;

The (00l) crystal plane (or ab plane) of the LDHs film is perpendicular to the substrate surface, highly oriented, compact, and the film thickness is 0.5-5 microns.

Concrete synthetic steps of the present invention are as follows:

A: Press the sulfonatable polymer material into tablets of different shapes and sizes as required, soak in commercially available concentrated sulfuric acid for 1-6 days to make it fully sulfonated, take it out and rinse it with deionized water, 30-60°C Set aside to dry.

B: In the reaction vessel, the soluble divalent inorganic salt M ²⁺ Y and the soluble trivalent inorganic salt M ³⁺ Y are prepared into a mixed salt solution at a molar ratio of 1.6 to 4.5:1, and the formula is [urea]/[Y ^- ] = Add urea in a ratio of 2 to 6 and make it dissolve.

C: Suspend the surface sulfonated polymer material substrate horizontally in the solution, seal the container, and react at a constant temperature of 50-100°C for 3-12 days, and the preferred reaction condition is at a temperature of 60-90°C React at a constant temperature for 5-9 days; after the solution is cooled, take out the substrate of the polymer material, rinse it with deionized water, and dry it. The film formed on the surface of the polymer material is the LDHs film.

The sulfonatable polymer material in step A is polystyrene, styrene-divinylbenzene copolymer, polyacene or polyaniline.

The immersion time of the substrate described in step A in the concentrated sulfuric acid is related to the substrate material, and the substrate after sulfonation should reach the following index: measure with probe X-ray photoelectron spectroscopy (XPS) instrument (UK Thermo VG ScientificSigma) The molar ratio of S/C on the surface of the substrate is greater than 0.035, or the water contact angle measured by JC2000A static drop contact angle/interfacial tension measuring instrument (Shanghai Zhongchen Digital Technology Equipment Co., Ltd.) is less than 15.0°.

In step B, M ²⁺ is any one of Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ , preferably Mg ²⁺ or Ni ²⁺ ; M ³⁺ is Al ³ Any one of ⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ , preferably Al ³⁺ , Y is Cl ^- , NO ₃ ^- , F ^- Any one of , Br ^- , SO ₄ ^2- , preferably NO ₃ ^- .

Urea is a very weak Brnsted base (pK _b =13.8) and has high solubility in water. The decomposition mechanism of urea in water is shown in the following reaction formula:

CO(NH ₂ ) ₂ →NH4 _C NO: slow

NH ₄ CNO+2H ₂ O→(NH ₄ ) ₂ CO ₃ : fast

The rate constant of this reaction can increase about 200 times when the temperature is increased from 60°C to 100°C. After hydrolysis of the produced ammonium carbonate, OH ^- and CO ₃ ^2- can be provided to the solution, so that the pH value of the solution is around 7-9, thereby providing suitable pH conditions for the synthesis of LDHs. The present invention controls the synthesis temperature of step C To control the release rate of anion OH ^- and CO ₃ ^2- , and then successfully control the nucleation and growth of LDHs crystals.

After sulfonation of the surface of the polymer material substrate, the hydrophobic surface is transformed into a hydrophilic surface. The sulfonic acid group provides a surface negative charge for the biomimetic synthesis of LDHs film, and absorbs and enriches metal cations in the reaction solution through electrostatic interaction. Compared with the bulk solution, since the surface of the polymer material substrate is enriched with more metal ions, when urea slowly decomposes to release OH ^- and CO ₃ ^2- , the ion concentration on the surface of the substrate reaches supersaturation first, thereby Preferential formation of aligned LDHs nuclei. With the further decomposition of urea, the LDHs nuclei on the surface of the substrate grow directionally, and finally an oriented LDHs film is obtained.

The magnesium aluminum carbonate LDHs powder (a), the magnesium aluminum carbonate LDHs film (b) prepared by the present invention, the polystyrene matrix (c), and the The nickel aluminum carbonate LDHs film (d) and the nickel aluminum carbonate LDHs powder (e) prepared by the invention, the results are shown in Figure 1, from Figure 1 it can be seen that the XRD spectrum of the magnesium aluminum carbonate film is broadly diffracted in the polystyrene matrix There are two more sharp diffraction peaks on the peak spectrum, and one more sharp diffraction peak on the spectrum of nickel aluminum carbonate LDHs thin film. The diffraction peak at the low angle of magnesium aluminum carbonate LDHs film can be attributed to the (003) diffraction peak of magnesium aluminum carbonate LDHs (d ₀₀₃ =0.763nm), the second diffraction peak in the XRD spectrum of magnesium aluminum carbonate LDHs film (d _hkl = 0.257nm) cannot be attributed to the (012) diffraction peak of LDHs, because the intensity of all (01l) peaks (l = 3n-1) should be equivalent, and no other (01l) diffraction peaks appear in the figure, This diffraction peak is closer to the (009) diffraction peak (calculated d ₀₀₉ =0.254 nm). Both (01l) and (11l) diffraction peaks appear in the XRD pattern of LDHs powder with disordered orientation, and the absence of (01l) and (11l) diffraction peaks in LDHs film indicates that it has a high degree of orientation.

The JSM-75000F Field Emission Scanning Electron Microscope (FESEM) from Japan JEOL Company was used to observe the morphology of the film surface and its cross-section. The samples used to observe the cross-section were prepared by liquid nitrogen freeze-fracture method, and all FESEM samples were sprayed with gold. From the FESEM photos (Fig. 2-5), it can be clearly seen that the (00l) crystal plane (or ab plane) of the LDHs sheet on the LDHs film is perpendicular to the surface of the substrate. Obviously, a highly oriented and very dense LDHs film is formed on the surface of the sulfonated polymer material substrate. The thickness of these LDHs films are all in the micron order.

It can be seen from Figure 6 that the LDHs film cannot be obtained on the polymer material substrate without sulfonation on the surface; it can be seen from Figure 7 that the LDHs sheet arrangement in the LDHs film obtained on the surface partly sulfonated polymer material substrate Disorder; it shows that dense and highly oriented LDHs films can only be obtained on the surface of fully sulfonated polymer material substrates.

The remarkable effect of the present invention lies in that the (00l) crystal plane (or ab plane) of the LDHs thin film prepared by the present invention is perpendicular to the surface of the substrate, highly oriented, compact, and has a thickness of 0.5-5 microns. By adopting the method provided by the invention, the LDHs thin film can be biomimetically synthesized on the sulfonatable polymer material matrix, and the synthesis method is simple and convenient.

Description of drawings

Fig. 1 is the XRD spectrogram of embodiment 1 and embodiment 4 gained film sample and comparative sample, wherein

a is the curve of magnesium aluminum carbonate LDHs powder;

b is the curve of magnesium aluminum carbonate LDHs film;

c is the curve of the polystyrene matrix;

d is the curve of nickel aluminum carbonate LDHs film;

e is the curve of nickel aluminum carbonate LDHs powder;

Fig. 2 is the FESEM photograph of embodiment 1 gained magnesium aluminum carbonate radical LDHs film sample surface;

Fig. 3 is the FESEM photograph of embodiment 1 gained magnesium aluminum carbonate LDHs film sample section;

Fig. 4 is the FESEM photograph of embodiment 4 gained nickel aluminum carbonate LDHs film sample surface;

Fig. 5 is the FESEM photograph of embodiment 4 gained nickel aluminum carbonate LDHs film sample section;

Fig. 6 is the FESEM photo of embodiment 7 gained sample surface;

Fig. 7 is the FESEM photo of the magnesium aluminum carbonate LDHs film sample surface obtained in embodiment 8.

Detailed ways

Below in conjunction with embodiment the present invention will be further described:

Example 1

Polystyrene was hot-pressed into sheets, soaked in commercially available concentrated sulfuric acid for 3 days, rinsed with deionized water, and dried at 40°C for later use.

In a 1000mL reaction vessel, dissolve 1.923gMg(NO ₃ ) ₂ 6H ₂ O and 1.407gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.015mol/L . After adding 6.306g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 70°C for 9 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The film formed on the surface of polystyrene is magnesium aluminum carbonate LDHs film, the molar ratio of Mg/Al in the film is 1.61, and the content of Al on the film surface is 0.0143mol/m ² . Its XRD spectrum is shown in Figure 1(b), and the FESEM photos are shown in Figure 2 and Figure 3 respectively. It can be seen that the film thickness is about 1.82 μm, dense and well oriented.

Example 2

Polystyrene was hot-pressed into sheets, soaked in commercially available concentrated sulfuric acid for 3 days, rinsed with deionized water, and dried at 40°C for later use.

In a 1000mL reaction vessel, dissolve 0.288g of Mg(NO ₃ ) ₂ 6H ₂ O and 0.141g of Al(NO ₃ ) ₃ 9H ₂ O in 750mL of deionized water at a molar ratio of 4:1 to prepare the total metal ion A solution with a concentration of 0.002mol/L. After adding 0.608g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 60°C for 12 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The film formed on the surface of polystyrene is the magnesium aluminum carbonate LDHs film obtained. The Mg/Al molar ratio in the film is 1.84, the film thickness is about 1.70 μm, and the Al content on the film surface is 0.0127 mol/m ² , which is dense and oriented Good sex.

Example 3

Styrene-divinylbenzene copolymer was hot-pressed into sheets, soaked in commercially available concentrated sulfuric acid for 5 days, rinsed with deionized water, and dried at 30°C for use.

In a 1000mL reaction vessel, dissolve 1.923gMg(NO ₃ ) ₂ 6H ₂ O and 1.407gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.015mol/L . After adding 6.306g of urea and dissolving it, suspend the surface sulfonated styrene-divinylbenzene copolymer substrate horizontally in the solution, seal the container, and react at a constant temperature of 90°C for 3 days. After the solution was cooled, the styrene-divinylbenzene copolymer sheet was taken out, rinsed with deionized water, and dried at 50°C for 24 hours.

The film formed on the surface of styrene-divinylbenzene copolymer is the obtained magnesium aluminum carbonate LDHs film. The Mg/Al molar ratio in the film is 1.66, the Al content on the film surface is 0.0139mol/m ² , and the film thickness is about 1.97μm, dense and well oriented.

Example 4

The hot-pressed polystyrene sheets were soaked in commercially available concentrated sulfuric acid for 3 days, rinsed with deionized water, and dried at 40°C for later use.

In a 1000mL poly reaction vessel, 2.181gNi(NO ₃ ) ₂ ·6H ₂ O and 1.407gAl(NO ₃ ) ₃ ·9H _2O were dissolved in 750mL deionized water to make a total metal ion concentration of 0.015mol/L solution. After adding 6.306g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 70°C for 9 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The film formed on the surface of polystyrene is the obtained nickel aluminum carbonate LDHs film. The molar ratio of Ni/Al in the film is 1.90, and the content of Al on the film surface is 0.0154mol/m ² . The XRD spectrum is shown in Figure 1(d) , FESEM photos are shown in Figures 4 and 5, respectively. It can be seen that the film thickness is about 1.67 μm, dense and well oriented.

Example 5

The hot-pressed polystyrene sheets were soaked in commercially available concentrated sulfuric acid for 3 days, rinsed with deionized water, dried at 30°C, and then used.

In a 1000mL reaction vessel, dissolve 13.19gNi(NO ₃ ) ₂ 6H ₂ O and 5.63gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.080mol/L . Proportion After adding 24.32g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 90°C for 3 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The film formed on the surface of polystyrene is the obtained nickel aluminum carbonate LDHs film. The molar ratio of Ni/Al in the film is 2.83, the content of Al on the film surface is 0.0106mol/m ² , and the film thickness is about 2.06μm. It is dense and oriented Good sex.

Example 6

Styrene-divinylbenzene copolymer was hot-pressed into sheets, soaked in commercially available concentrated sulfuric acid for 5 days, rinsed with deionized water, and dried at 40°C for use.

In a 1000mL reaction vessel, dissolve 0.436gNi(NO ₃ ) ₂ 6H ₂ O and 0.141gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.0025mol/L . After adding 1.486g of urea and dissolving it, the surface sulfonated styrene-divinylbenzene copolymer sheet was horizontally suspended in the solution, and after the container was sealed, it was reacted at a constant temperature of 60°C for 12 days. After the solution was cooled, the styrene-divinylbenzene copolymer sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The film formed on the surface of styrene-divinylbenzene copolymer is the obtained nickel aluminum carbonate LDHs film. The molar ratio of Ni/Al in the film is 3.68, the content of Al on the film surface is 0.0091mol/m ² , and the film thickness is about 1.66μm, dense and well oriented.

Embodiment 7 (comparative example)

After hot-pressing the polystyrene into a sheet, rinse it with deionized water, dry it at 40°C and set it aside.

In a 1000mL reaction vessel, dissolve 1.923gMg(NO ₃ ) ₂ 6H ₂ O and 1.407gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.015mol/L . After adding 6.306g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 70°C for 9 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The FESEM photo of its surface is shown in Figure 6, and it can be seen that no magnesium aluminum carbonate LDHs film is formed on the surface of polystyrene.

Embodiment 8 (comparative example)

The polystyrene is hot-pressed into sheets, soaked in concentrated sulfuric acid in the city for 3 days, rinsed with deionized water, dried at 40°C and used for later use.

In a 1000mL reaction vessel, dissolve 1.923gMg(NO ₃ ) ₂ 6H ₂ O and 1.407gAl(NO ₃ ) ₃ 9H ₂ O in 750mL deionized water to prepare a solution with a total metal ion concentration of 0.015mol/L . After adding 6.306g of urea and dissolving it, suspend the surface sulfonated polystyrene sheet horizontally in the solution, seal the container, and react at a constant temperature of 70°C for 9 days. After the solution was cooled, the polystyrene sheet was taken out, rinsed with deionized water, and dried at 40°C for 24 hours.

The FESEM photo of its surface is shown in Figure 7. It can be seen that the continuity of the magnesium aluminum carbonate LDHs film formed on the surface of polystyrene is poor, and the arrangement of LDHs is chaotic.

Claims (7)

1. A layered double hydroxyl compound metal oxide thin film is a LDHs film grown on a polymer material substrate, and the general chemical formula of the film layer LDHs is: [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ (CO ₃ ^2- ) _x/2 ·yH ₂ O), Among them, M ²⁺ represents any of divalent metal ions Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ ; M ³⁺ represents trivalent metal ions Al ³⁺ , Cr ³⁺ , Any one of Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ ; 0.2≤x≤0.4, 0≤y≤2; The (00l) crystal plane of the LDHs film is vertical to the substrate surface, highly oriented and compact, and has a film thickness of 0.5-5 microns. 2. layered double hydroxyl complex metal oxide thin film according to claim 1, it is characterized in that macromolecular material matrix is any in polystyrene, styrene-divinylbenzene copolymer, polyacene or polyaniline A sort of. 3. The layered bishydroxy compound metal oxide thin film according to claim 1, characterized in that M ²⁺ is Mg ²⁺ or Ni ²⁺ ; M ³⁺ is Al ³⁺ . 4. a kind of preparation method of layered double hydroxyl composite metal oxide film as claimed in claim 1, concrete steps are as follows: A: Press the sulfonatable polymer material into tablets of different shapes and sizes as required, soak in commercially available concentrated sulfuric acid for 1-6 days to make it fully sulfonated, take it out and rinse it with deionized water, 30-60°C Dry down for later use; B: In the reaction vessel, the soluble divalent inorganic salt M ²⁺ Y and the soluble trivalent inorganic salt M ³⁺ Y are prepared into a mixed salt solution at a molar ratio of 1.6 to 4.5:1, and the formula is [urea]/[Y ^- ] = 2 ~ 6 ratio to add urea and make it dissolve; wherein M ²⁺ is any one of Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ , and M ³⁺ is Al ³ Any one of ⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ ; Y is Cl ^- , NO ₃ ^- , F ^- , Br ^- , SO ₄ ^2- any of the C: Suspend the surface sulfonated polymer material substrate horizontally in the solution, seal the container, and react at a constant temperature at 50-100°C for 3-12 days, take out the polymer material substrate after the solution is cooled, and use After rinsing with ionized water and drying, the film formed on the surface of the polymer material is the LDHs film. The general chemical formula of the film layer LDHs is: [M _{2+ 1-x} M ³⁺ _x (OH) ₂ ] ^x+ (CO ₃ ^2- ) _x/2 ·yH ₂ O) Among them, M ²⁺ represents any of divalent metal ions Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ ; M ³⁺ represents trivalent metal ions Al ³⁺ , Cr ³⁺ , Any one of Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ ; 0.2≤x≤0.4, 0≤y≤2; the (00l) crystal plane of the LDHs film is perpendicular to the substrate surface , Highly oriented, dense, with a film thickness of 0.5-5 microns. 5. the preparation method of layered double hydroxyl composite metal oxide film according to claim 4 is characterized in that, the sulfonatable macromolecular material described in step A is polystyrene, styrene-divinylbenzene copolymerization substances, polyacene or polyaniline; the immersion time of the substrate in concentrated sulfuric acid is related to the material of the substrate, and the sulfonated substrate should meet the following indicators: the molar ratio of S/C on the surface of the substrate is greater than 0.035, and the static drip The water contact angle is less than 15.0°. 6. the preparation method of layered double hydroxyl compound metal oxide thin film according to claim 4 is characterized in that, in step B M ²⁺ is Mg ²⁺ or Ni ²⁺ ; M ³⁺ is Al ³⁺ ; Y is NO ₃ ^- . 7 . The method for preparing layered double hydroxy composite metal oxide film according to claim 4 , characterized in that the reaction in Step B and Step C is a constant temperature reaction at 60-90° C. for 5-9 days.

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