WO2008046343A1

WO2008046343A1 - Manganese dioxide / hydrotalcite inorganic nano flake composite film and its preparation method

Info

Publication number: WO2008046343A1
Application number: PCT/CN2007/070829
Authority: WO
Inventors: Wensheng Yang; Yi Wang; Xiong Zhang
Original assignee: Beijing University Of Chemical Technology
Priority date: 2006-10-12
Filing date: 2007-09-29
Publication date: 2008-04-24
Also published as: CN1948159A; CN100390066C

Abstract

A manganese dioxide / hydrotalcite inorganic nano flake composite film and its preparation are provided. The technical field belongs to material of inorganic film and its preparation. The chemical composition general formula of the composite film is (ns-MnO2 / ns-LDHs)m, in which ns-MnO2 is manganese dioxide nano flake, from which a laminated sheet with negative charge is formed, ns-LDHs is hydrotalcite nano flake, from which a laminated sheet with positive charge is formed, m is layer number of said composite film, m is greater than or equal to 1. By utilizing electrostatic self-assembly technique, the manganese dioxide nano flake, from which a laminated sheet with negative charge is formed, and the hydrotalcite nano flake, from which a laminated sheet with positive charge is formed, are successively assembled on the surface treated substrate, thereby obtaining said inorganic nano flake composite film. The inorganic nano flake composite film can be used as UV shielding material or electrode material of alkaline battery, in addition, the inorganic nano flake composite film can be used in the field of photovoltaic conversion, photoelectrocatalysis, sensor of electrochemistry and so on.

Description

Manganese dioxide/hydrotalcite inorganic nanosheet composite film and preparation method thereof

The invention belongs to the technical field of inorganic thin film materials and preparation thereof, and particularly relates to a manganese dioxide/hydrotalcite inorganic nanosheet composite film and a preparation method thereof. Background technique

The inorganic layered compound can be obtained into a single layer or a plurality of thin layer nanosheets by a layer stripping technique.

(nanosheet). Inorganic nanosheets generally have a thickness of one nanometer to several nanometers, a lateral dimension of several tens of nanometers to several micrometers, and thus have high anisotropy and high specific surface area; inorganic nanosheets are only a few nanometers thick and have significant Nano-effects, with unique optical, electrical, magnetic, and thermal properties; inorganic nanosheets have precise chemical composition and two-dimensional crystal structure, and each nanosheet can be regarded as a single crystal.

Based on the structural characteristics of nanosheets, inorganic nanosheets and polymers were assembled by electrostatic layer self-assembly technology. A variety of organic/inorganic, inorganic/inorganic films have been successfully prepared and exhibited various performance characteristics.

In the literature Chem. Mater., 2003, 15:2873-2878, Lianzhou Wang et al. prepared a polydiallyldimethylammonium (PDDA) polycation and a manganese dioxide nanosheet by electrostatic self-assembly technique. Organic/inorganic multilayer film. A single-layer branched polyvinylamine (PEI) / MnO ₂ nanosheet film electrode deposited on the surface of indium tin oxide (ITO) conductive glass is used as the working electrode, Ag/Ag+/acetonitrile electrode is used as the reference electrode, and the glassy carbon electrode is used as the auxiliary electrode. Electrode, 0.1 mol/L LiClO ₄ propylene carbonate (PC) solution was used as an electrolyte for electrochemical cyclic voltammetry. The PEI/MnO ₂ nanosheet film electrode was at -0.66 V (vs. Ag/Ag ⁺ / acetonitrile). There is a reduction peak at -0.36V and 0.23V (vs. Ag/Ag+/acetonitrile) with two oxidation peaks corresponding to the electrochemical transition between Mn ³⁺ and Mn ⁴⁺ in the manganese dioxide nanosheet.

In the literature Chem. Mater., 2005, 17:1352-1357, Lianzhou Wang et al.

[ΑΙΟ ₄ ΑΙ ₁₂ (ΟΗ) ₂ 4 (; Η ₂ Ο) ₁₂ ] ⁷⁺ (; ΑΙ ₁₃ ;) Polycation and manganese dioxide nanosheets An inorganic/inorganic multilayer film was prepared by electrostatic self-assembly technique. The multilayer film is used as a working electrode, the Ag/Ag+/acetonitrile electrode is used as a reference electrode, and the platinum black electrode is used as an auxiliary electrode for electrochemical cyclic voltammetry. After the first 20 to 30 cycles, a stable cyclic volt can be formed. Anthracene, whose oxidation and reduction peaks correspond to manganese dioxide Oxidation/reduction of manganese in rice flakes and extraction/intercalation of lithium ions.

In the literature J. Am. Chem. Soc, 2006, 128:4872-4880, Zhaoping Liu et al. prepared a polysulfonated styrene (PSS) polyanion and cobalt aluminum hydrotalcite nanosheet by electrostatic self-assembly technique. An organic/inorganic composite film having a remarkable magneto-optical effect.

At present, self-assembly techniques based on inorganic nanosheets mostly use organic polymers or inorganic polymers as a medium for connecting nanosheets. So far, no technique has been reported in the literature for directly assembling two nanosheets with opposite charges. Summary of the invention

The object of the present invention is to directly electrostatically assemble a negatively charged manganese dioxide nanosheet and a positively charged hydrotalcite nanosheet to obtain a novel manganese dioxide/hydrotalcite inorganic nanosheet composite film. The nano-synergy effect of the two nanosheets enhances the functionality of the single nanosheet and provides new functions and applications for the composite film.

The invention firstly provides a manganese dioxide/hydrotalcite inorganic nanosheet composite film, and the chemical composition formula of the manganese dioxide/hydrotalcite inorganic nanosheet composite film is (n _S -M _n O ₂ /n _S -LDH _S ) _m , wherein ns-MnO ₂ is a negatively charged manganese dioxide nanosheet, ns-LDHs is a layer of positively charged hydrotalcite nanosheets, m is the number of layers of the composite film, m^l.

In the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention, the layer m of the composite film is usually lm 30, and the overall thickness of the film is 2 to 100 nm. Since the overall thickness is nanometer, the film of the present invention can also be used. Called "ultra-thin film".

In the manganese dioxide/hydrotalcite inorganic nanosheet composite film provided by the invention, the manganese dioxide nanometer

Μη ³⁺ and Μη ⁴⁺ represent manganese ions of +3 valence and +4 valence, respectively, δ and l-δ are the fractions of the substances of +3 valence and +4 valence manganese ions, respectively, δ- is the manganese dioxide nanosheet The negative charge; the manganese octahedron forms a sheet-like structure by co-edge, the sheet structure has a thickness of 0.6 to 10 nm, and the length and width are in the range of 50 to 300 nm. The chemical composition of the hydrotalcite nanosheet is [Μ ²⁺ _1-β Μ ³⁺ _β (ΟΗ) ₂ ] ^β+ _; Μ ²⁺ represents +2 valent metal ions Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , One of Fe ²⁺ and Mn ²⁺ is preferably Mg ²⁺ ; M ³⁺ represents +3 valent metal ions Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ^{One of 3+} and Ti ³⁺ , preferably Al ³⁺ ; the amount of substances in which l-β and β are +2 valence and +3 valent metal ion, respectively Number, and 0.2 β 0.4; β+ is a positive charge of the hydrotalcite nanosheet; the metal ion and the hydroxide ion form an octahedron by covalent bond, and the sheet structure is formed by co-edge forming, the thickness of the sheet structure is 0.6 ~5nm, its length and width are in the range of 50~500nm.

The invention also provides a preparation method of the manganese dioxide/hydrotalcite inorganic nanosheet composite film, which mainly comprises a negatively charged manganese dioxide nanosheet and a layer of positively charged hydrotalcite by electrostatic self-assembly technology. The nanosheet is repeatedly assembled to the surface treated substrate in sequence. Specifically, the method for preparing the manganese dioxide/hydrotalcite inorganic nanosheet composite film comprises the steps of:

Taking a cleaned substrate, immersing it in an aqueous solution of about 1.0 to 1.5 g / L of branched polyvinylamine for about 15 to 30 minutes, taking it out, and drying it with N _{2 to} obtain a positively charged substrate;

The positively charged substrate is immersed in a manganese dioxide nanosheet sol having a negatively charged manganese dioxide nanosheet concentration of about 0.01 to 0.40 g/L for about 10 to 30 minutes, and then taken out, rinsed with distilled water. Clean, re-immersed into the hydrotalcite nanosheet sol with a positive charge of hydrotalcite nanosheets at a concentration of about 0.01~0.40g/L for about 10~30 minutes, then remove it with distilled water to complete a layer of manganese dioxide. Preparation of a hydrotalcite nanosheet composite film;

Repeating the above steps, that is, the substrate with a layer of manganese dioxide/hydrotalcite nanosheet composite film is sequentially immersed into the manganese dioxide nanosheet sol and the hydrotalcite nanosheet sol, respectively, to prepare a plurality of layers. Manganese dioxide/hydrotalcite inorganic nanosheet composite film. Usually, the number m of layers of the composite film can be controlled to be 1 m 30 to maintain a good bonding force between the composite film and the substrate.

According to a specific embodiment of the present invention, the method for preparing the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention may further comprise preparing the laminate negatively charged manganese dioxide nanosheet according to the following steps to prepare a solution The process of the concentration of the manganese dioxide nanoplate sol, gP, the negatively charged manganese dioxide nanosheet of the laminate can be prepared according to the following steps:

The ratio of ΟΗ· to Mn ²⁺ is about 3:1~4:1, and the ratio of H ₂ O ₂ to Mn ²⁺ is about 6:1~8:1, which will contain about 0.6~0.8mol. /L NaOH and a mixed solution of about 1.0~1.5mol / L H ₂ O ₂ is added to about 0.3~0.4mol / L of Mn (NO ₃ ;> ₂ solution, stirred for about 20~30 minutes, filtered, collecting filter cake; And adding NaOH solution with a concentration of about 2.0~3.0mol/L to the filter cake according to the ratio of ΟΗ· and MnO _{2 to} about 2:1~4:1, stirring in a paste, hydrothermal treatment at 150~160°C After about 15~20 hours; then naturally cool to room temperature, suction filtration, wash the filter cake with distilled water until the pH of the filtrate is about 8~9, and the filter cake is about 70~ Drying in an air atmosphere at 80 ° C for about 6 to 9 hours to obtain layered manganese dioxide;

According to the amount ratio of H+ to the layered manganese dioxide substance is about 10:1 to 15:1, the layered manganese dioxide is added to the HNO ₃ solution having a concentration of about 1.0 to 1.5 mol/L, and the reaction is stirred at room temperature for about 3 ~5 days, during which time a new 1.0~1.5mol/L HNO ₃ solution is replaced every 24 hours. After the reaction is finished, the mixture is filtered by suction and washed with distilled water until the pH of the filtrate is about 6~7. The cake is dried in an air atmosphere of about 70 to 80 ° C for about 6 to 9 hours to obtain a hydrogen exchange layered manganese dioxide;

The hydrogen exchange layered manganese dioxide is added to a mass fraction of about 1.5% to 2.0% by an amount ratio of tetramethylammonium hydroxide to hydrogen exchanged layered manganese dioxide of about 2:1 to 4:1. In a tetramethylammonium hydroxide aqueous solution, the reaction is stirred at room temperature for about 7 to 10 days, and centrifuged (the mixture can be centrifuged at about 10,000 to 12,000 rpm for about 5 to 15 minutes, and washed with distilled water. The precipitate is separated, and the lower layer precipitate is a negatively charged manganese dioxide nanosheet. The manganese dioxide nanosheet can be prepared by adding water to prepare a manganese dioxide nanosheet sol of the desired concentration of the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention.

The precipitate obtained above was characterized by X-ray diffraction analysis. The XRD pattern showed that the diffraction peak of the layered structure characteristic of the hydrogen exchange layered manganese dioxide disappeared, and it was confirmed that the negatively charged manganese dioxide nanosheet was obtained. . The chemical composition of the manganese dioxide nanosheet can be used

Among them, Mn ³⁺ and Mn ⁴⁺ represent manganese ions of +3 and +4, respectively, and δ and l-δ are the fractions of substances with +3 and +4 valent manganese ions, respectively, and δ- is manganese dioxide nanometer. The sheet is negatively charged, and the manganese octahedron forms a sheet-like structure by co-edge. The sheet structure has a thickness of about 0.6 to 10 nm and a length and a width of about 50 to 300 nm.

According to a specific embodiment of the present invention, the method for preparing the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention may further comprise preparing the laminate positively charged hydrotalcite nanosheet according to the following steps to formulate the The process of concentration of the hydrotalcite nanoplate sol, gP, the layer of positively charged hydrotalcite nanoplate sol can be prepared according to the following steps:

The soluble salt of M ^{2+ and} the soluble salt of M ³⁺ are dissolved in distilled water according to the ratio of M ²⁺ /M ³⁺ substance in an amount of about 1.5 to 4, and mixed into a salt solution to make M ²⁺ The concentration is about 0.1~1.6mol/L; the NaOH is dissolved in distilled water to prepare an alkali solution having a concentration of about 0.5~2.0 mol/L; the two solutions are simultaneously dropped into the glycine aqueous solution under the protection of N ₂ . Obtaining a slurry in which the amount of glycine substance is M ³⁺ The amount of the mass is about 1 to 4 times, and the pH of the system is maintained at about 8 to 12 during the dropwise addition; the slurry obtained above is crystallized under the protection of N ₂ at about 40 to 90 ° C for about 2~ 24 hours, washing, filtration, vacuum drying the filter cake at room temperature for about 12~24h, to obtain glycine intercalated hydrotalcite;

According to the ratio of glycine intercalated hydrotalcite mass/formamide volume to about 1~5g/L, the glycine intercalated hydrotalcite is weighed into the corresponding volume of formamide, and the reaction is stirred for about 1~3 hours to obtain a clear and transparent sol. The transparent sol is a sol of a layer of positively charged hydrotalcite nanosheets. The transparent sol of the hydrotalcite nanosheet can be appropriately diluted with water to prepare a hydrotalcite nanoplate sol having a desired concentration for preparing the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention.

1 to 2 drops of the above-obtained transparent sol were dropped on a frosted glass sheet for X-ray diffraction analysis, and the XRD spectrum showed that the diffraction peak of the layered structure characteristic of the glycine intercalated hydrotalcite disappeared, and it was confirmed that the layer was positively charged. Talc nanosheets. The metal ion and the hydroxide ion in the hydrotalcite nanosheet form a octahedron by covalent bond, and form a sheet structure by co-edge, the thickness of the sheet structure is about 0.6~5 nm, and the length and width thereof are about 50~ Within the range of 500 nm. Specifically, the chemical composition of the hydrotalcite nanosheet can be represented by [M ²⁺ ₁ .pM ³ 3⁄4OH) ₂ ] ^p+ , wherein M ²⁺ represents a +2 valent metal ion Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ^{One of 2+} and Mn ²⁺ , preferably Mg ²⁺ ; M ³⁺ represents +3 valent metal ions Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ^{3 +} , Ti ³⁺ , preferably Al ³⁺ ; l-β and β are the fractions of the +2 and +3 valent metal ions, respectively, 0.2 β 0.4; β+ is hydrotalcite nano The film has a positive charge.

In the above method for preparing a positively charged hydrotalcite nanosheet, the soluble salt of Μ ²⁺ may be nitrate of Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ , chlorine One of a salt or a sulfate, the soluble salt of M ³⁺ may be a nitrate of Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ , chlorine One of a salt or a sulfate.

In the method for preparing the manganese dioxide/hydrotalcite inorganic nanosheet composite film of the present invention, the substrate may be a quartz substrate, a single crystal silicon substrate, or an indium tin oxide (ITO) conductive glass substrate. One. Preferably, the various substrates should be ultrasonically cleaned in advance in the washing liquid to remove surface contaminants and then immersed in the aqueous solution of the branched polyvinylamine for activation, specifically, the surface of various substrates. The cleaning methods can be:

(1) The quartz substrate may be a substrate cleaned by the following steps: The quartz substrate is ultrasonically washed successively with acetone, absolute ethanol, and distilled water for about 20 to 30 minutes, and then immersed in an aqueous solution of H ₂ O ₂ (H). ₂ O ₂ quality The amount is about 30%~33%) and the concentrated sulfuric acid (sulfuric acid mass fraction is about 95%~98%) is ultrasonically cleaned in a washing solution prepared by a volume ratio of about 3:7 (can be cleaned until no bubbles are generated), and then Re-immersed in H ₂ O ₂ aqueous solution (H ₂ O ₂ mass fraction is about 30%~33%), concentrated ammonia water (ammonia mass fraction is about 25%~28%) and distilled water is prepared by volume ratio of 1:1:5. Ultrasonic cleaning in the wash solution (can be washed until no air bubbles are generated), and finally rinsed with distilled water and then dried with N ₂ .

(2) The single crystal silicon substrate may be a substrate cleaned by the following steps: The single crystal silicon substrate is prepared by using methanol and concentrated hydrochloric acid (hydrogen hydrochloric acid mass fraction of about 36% to 38%) at a volume ratio of about 1:1. Ultrasonic cleaning in the washing solution for about 20 to 30 minutes, followed by ultrasonic cleaning with concentrated sulfuric acid (sulfuric acid mass fraction of about 95% to 98%) for about 20 to 30 minutes, and finally rinsed with distilled water, and then dried with N ₂ .

(3) The indium tin oxide (ITO) conductive glass substrate may be a substrate cleaned by the following steps: The indium tin oxide conductive glass substrate is sequentially ultrasonically cleaned with acetone, absolute ethanol, and distilled water for about 20 to 30 minutes. , then immersed in H ₂ O ₂ aqueous solution (H ₂ O ₂ mass fraction is about 30%~33%), concentrated ammonia water (ammonia mass fraction is about 25%~28%) and double distilled water by volume ratio 1:1: Ultrasonic cleaning in the wash solution prepared around 5 (can be cleaned until no air bubbles are generated), and finally rinsed with distilled water and then dried with N ₂ . The invention also adopts the Shimadzu XRD-6000 X-ray powder diffractometer (XRD) (Cu K«^, λ=1.5406Α) to characterize the film structure, and utilizes the layered structure characteristic diffraction peak intensity with the number of assembled layers. The change tracked the assembly process of the multilayer film and the results showed that the assembly process of the film was continuous and uniform.

The invention also uses the Shimadzu UV-2501PC ultraviolet-visible spectrophotometer to characterize the ultraviolet absorption property of the film, and the results show that the inorganic nanosheet composite film of the invention has good ultraviolet in a wide ultraviolet region of about 200 to 400 nm. Absorption performance, its maximum absorption peak is around 380nm, and it can be used as UV shielding film material.

The inorganic nanosheet composite film of the present invention also has new functions and applications. The invention relates to a manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film assembled on an indium tin oxide (ITO) conductive glass substrate (see Example 5) as a working electrode, and a Hg/HgO electrode as a reference electrode, large area. Platinum wire is the auxiliary electrode, lmol/L NaOH aqueous solution is used as the electrolyte, assembled into a three-electrode test system, and subjected to cyclic voltammetry test using ZMHer's IM6e electrochemical workstation in Germany. The potential scanning range is 0.0~0.6V (vs. Hg/ HgO), scan rate ΐΓην·. Electrochemical test results show that the inorganic nanosheet composite film can It is used as a positive electrode material for alkaline secondary batteries and has good electrochemical properties.

The invention also electrochemically tests the manganese dioxide/hydrotalcite inorganic nanosheet film obtained in other embodiments, and the results show that: the manganese dioxide nanosheet and the nickel aluminum hydrotalcite, the cobalt aluminum hydrotalcite, etc. in the invention Composite films obtained by electrochemically active nanosheet composites (see Examples 3, 4, and 5) can be used as alkaline battery electrode materials or supercapacitor electrode materials, respectively, which have good electrochemical properties. It has good UV absorption capacity, so it has potential application value in photoelectric conversion and photoelectric catalytic materials; composite film obtained by combining manganese dioxide nanosheets with zinc-aluminum hydrotalcite with good biocompatibility (see Example 1) , 6), can be used as an electrode material for electrochemical biosensors.

The effects and advantages of the present invention are: The present invention directly combines two functional nanosheets on a nanometer scale, that is, a negatively charged manganese dioxide nanosheet and a positively charged hydrotalcite nanosheet are directly electrostatically assembled. Thus, a novel structure manganese dioxide/hydrotalcite inorganic nanosheet composite film is obtained, and the nano synergistic effect of the two nanosheets can be achieved. Compared to a film containing only one type of nanosheet, the composite film of the present invention comprising two nanosheets can enhance the function of a single nanosheet or exhibit a new function not possessed by a single nanosheet film. Compared with the PDDA/MnO ₂ nanosheet composite film reported in the literature, the manganese dioxide/hydrotalcite nanosheet composite film of the invention not only has good ultraviolet absorption performance, but also has higher structural stability and thermal stability. . Moreover, depending on the chemical composition, the inorganic nanosheet composite film of the present invention can be used as a battery electrode material in the fields of photoelectric conversion, photoelectrocatalysis, and electrochemical sensors (in a broad sense, the present invention is used for photoelectric conversion, photoelectric Thin film materials in the field of catalysis can also be regarded as electrode materials) and have broad application prospects. DRAWINGS

1 is an X-ray diffraction spectrum of a hydrogen exchange layered manganese dioxide and manganese dioxide stripped nanosheet. Abscissa: Angle 2Θ, unit is. (Degrees); ordinate: intensity, the unit absolute unit _(a .u.). Wherein, the curve (a) is an X-ray diffraction spectrum of the hydrogen exchange layered manganese dioxide; and the curve (b) is an X-ray diffraction spectrum of the manganese dioxide stripped nanosheet.

2 is an X-ray diffraction spectrum of glycine intercalated zinc aluminum hydrotalcite (Ζη/Α1=3) and zinc aluminum hydrotalcite stripped nanosheets. Abscissa: Angle 2Θ, unit is. (degrees); ordinate: intensity, in absolute units (au). Among them, the curve (a) is the X-ray diffraction spectrum of glycine intercalated zinc-aluminum hydrotalcite (Ζη/Α1=3) Figure; Curve (b) is an X-ray diffraction spectrum of a zinc-aluminum hydrotalcite-peeled nanosheet.

Figure 3 shows the UV-visible absorption spectra of manganese dioxide/zinc-aluminum hydrotalcite nanosheet composite films with different layers. Abscissa: Wavelength, in nanometers (nm); ordinate: absorbance, no unit.

Figure 4 shows the relationship between the absorbance of the manganese dioxide/zinc-aluminum hydrotalcite nanosheet composite film at 380 nm and the number of layers assembled. Abscissa: Assemble the number of layers, the unit is layer; ordinate: absorbance at 380nm, no unit.

Fig. 5 is an X-ray diffraction spectrum of a composite film of different layers of manganese dioxide/magnesium aluminum hydrotalcite nanosheets. Abscissa: Angle 2Θ, unit is. (Degrees); ordinate: intensity, the unit absolute unit _(a .u.).

Figure 6 shows the electrochemical cyclic voltammetry curves of a manganese dioxide/nickel aluminum hydrotalcite nanosheet composite film. Abscissa: voltage in millivolts (mV); ordinate: current in milliamps per square centimeter (mA m- ² ). E ₀ : oxidation peak potential; E _R: reduction peak potential; E _OE: oxygen evolution potential. BEST MODE FOR CARRYING OUT THE INVENTION The technology and features of the present invention are described in detail below by way of specific examples, but these embodiments are not intended to limit the scope of the present invention. Example 1: Manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film and preparation method thereof a. Preparation of negatively charged manganese dioxide nanosheets on a laminate:

200 mL of a mixed solution containing 0.6 mol/L NaOH and 1.5 mol/L H ₂ O ₂ was added to 100 mL of a solution containing 0.4 mol/L Mn(NO 3 ) ₂ , stirred for 30 minutes, filtered, and the filter cake was transferred to 100 mL of poly In a tetrafluoroethylene cup; add 40 mL of a 2.0 mol/L NaOH solution to the Teflon cup, stir it into a paste, and then seal the Teflon cup in a hydrothermal kettle and hydrotreat at 160 °C. After 15 hours; the hydrothermal kettle was naturally cooled to room temperature, and the mixture was filtered under suction. The filter cake was washed with double distilled water until the pH of the filtrate was about 8, and the filter cake was dried in an air atmosphere at 70 ° C for 9 hours to obtain a layered shape. Manganese oxide solid powder;

2.5 g of the layered manganese dioxide solid powder obtained above was weighed and added to 300 mL of a 1.0 mol/L HNO ₃ solution, and stirred at room temperature for 3 days, during which a new 1.0 mol/L HNO was replaced every 24 hours. ₃ solution; the mixture was suction filtered, washed with double distilled water until the pH of the filtrate was 6, and the filter cake was dried in an air atmosphere at 70 ° C for 9 hours to obtain a hydrogen exchange layered manganese dioxide; 12 mL of tetramethylammonium hydroxide having a mass fraction of 25% was weighed and added to 188 mL of twice-distilled water to prepare a solution, and 1.4 g of the hydrogen exchange layered manganese dioxide obtained above was weighed and dispersed in the above tetramethyl group. In the ammonium hydroxide solution, the reaction was stirred at room temperature for 7 days; the mixture was centrifuged at 12,000 rpm for 10 minutes, washed twice with 400 mL of secondary distilled water, centrifuged, and the precipitate was subjected to X-ray diffraction analysis. For the XRD spectrum, please refer to FIG. 1 , wherein the curve (a) is an X-ray diffraction spectrum of the hydrogen exchange layered manganese dioxide; and the curve (b) is an X-ray diffraction spectrum of the precipitate obtained in the present embodiment, showing hydrogen exchange. The layered structure characteristic diffraction peak of the layered manganese dioxide disappeared, and it was confirmed that the negatively charged manganese dioxide stripped nanosheet of the laminate was obtained.

The layer of negatively charged manganese dioxide nanosheets was added with water to prepare a 0.20 g/L manganese dioxide nanosheet sol.

b. Preparation of positively charged zinc-aluminum hydrotalcite nanosheets:

The take 0.075mol _{_{Ζη (ΝΟ 3) 2 · 6Η}} 2 Ο and 0.025mol of _{_{Α1 (ΝΟ 3) 3 · 9Η}} 2 Ο, v ₂ in the de-protection was dissolved in CO ₂ in double distilled water to prepare a total metal ion a mixed salt solution having a concentration of 1.0 mol/L; taking 0.1 mol of NaOH, dissolved in a secondary distilled water of CO ₂ under N ₂ protection, and preparing an alkali solution having a concentration of 1.0 mol/L; taking 0.025 mol Glycine, dissolved in de-CO ₂ in double distilled water under the protection of 3⁄4, formulated into a concentration of 0.05 mol / L of glycine aqueous solution 500mL;

The mixed salt solution and the alkali solution are simultaneously dropped into the glycine aqueous solution under the protection of N ₂ , and the dropping rate of the NaOH solution is controlled during the dropwise addition and stirred to maintain the pH of the system at about 8, thereby obtaining a slurry; the resulting slurry under N ₂ at about 40 ° C crystallization about 6 hours, cooled to room temperature, washed twice with distilled water removal of CO _2, filtered and the filter cake was dried for 24 hours in vacuo to give intercalation zinc glycinate at room temperature Aluminum hydrotalcite powder;

0.10 g of the glycine intercalated zinc aluminum hydrotalcite powder obtained above was added to 100 mL of the formamide solution, and the reaction was stirred for 1 hour to obtain a clear and transparent sol; 1 drop of the sol was dropped on the frosted glass piece for X-ray diffraction analysis, XRD spectrum 2, wherein curve (a) is an X-ray diffraction spectrum of glycine intercalated zinc-aluminum hydrotalcite; curve (b) is an X-ray diffraction spectrum of the transparent sol obtained in the present example, showing glycine intercalated zinc aluminum The diffraction peaks of the layered structure of the hydrotalcite disappeared, and it was confirmed that the layered positive-charged zinc-aluminum hydrotalcite-peeled nanosheets were obtained.

The clarified transparent sol of the zinc-aluminum hydrotalcite nanosheet obtained above is added with water to prepare 0.20 g/L of zinc-aluminum water. Talc nanosheet sol.

C. Cleaning and activation of quartz substrate:

A quartz substrate was first washed with acetone, ethanol, after the second ultrasonic washing in distilled water for about 20 minutes each, and then immersed in an aqueous solution of H _₂ O ₂ (H _₂ O ₂ content of 30%) and concentrated sulfuric acid (sulfuric acid content 98%) Ultrasonic cleaning in a wash solution prepared at a volume ratio of 3:7 until no bubbles are generated, followed by immersion in an aqueous H ₂ O ₂ solution (H ₂ O ₂ mass fraction of 30%), concentrated ammonia (ammonia mass fraction) Ultrasonic cleaning of 28%) and double distilled water in a volume ratio of 1:1:5 until no bubbles were generated, and finally rinsed with a large amount of double distilled water and then dried with N ₂ . The cleaned quartz substrate was further immersed in an aqueous solution of 1.25 g/L of branched polyvinylamine (PEI) for 20 minutes, taken out, and dried with N _{2 to} obtain a positively charged quartz substrate.

d. Preparation of manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film:

The positively charged quartz substrate was immersed in a 0.20 g/L manganese dioxide nanosheet sol at room temperature in an air atmosphere, taken out after 20 minutes, rinsed with double distilled water, and dried under N ₂ ; Immerse in 0.20g/L zinc-aluminum hydrotalcite nanosheet sol, take it out after 20 minutes, rinse it with double distilled water, dry it with N ₂ , and complete a layer of manganese dioxide/zinc-aluminum hydrotalcite nanosheet composite film (assembly double Preparation of the number of layers m = l). Repeat the above operation as a multi-layer manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film.

The ultraviolet absorption properties of the composite film of the present embodiment were tested by an ultraviolet-visible spectrophotometer. Fig. 3 shows the ultraviolet-visible absorption spectra of the different layers of manganese dioxide/zinc-aluminum hydrotalcite nanosheet composite film, and the results show that the inorganic nanometer The composite film has a broad ultraviolet absorption peak at 380 nm and good ultraviolet absorption properties in a wide ultraviolet region of 200 to 400 nm, and can be used as an ultraviolet shielding film material, and has the advantages of high structural stability and high thermal stability. The relationship between the absorbance at 380 nm and the number of layers of the inorganic nanosheet composite film is shown in Fig. 4, which shows a good linear relationship, indicating that the assembly process of the inorganic nanosheet film is continuous and uniform. Example 2: Manganese dioxide / mirror aluminum hydrotalcite inorganic nanosheet composite film and preparation method thereof a. Preparation of negatively charged manganese dioxide nanosheets with laminate:

200 mL of a mixed solution containing 0.6 mol/L NaOH and 1.0 mol/L H ₂ O ₂ was added to 100 mL of a solution containing 0.3 mol/L Mn(NO 3 ) ₂ , stirred for 20 minutes, filtered, and the filter cake was transferred to 100 mL of poly In a tetrafluoroethylene cup; then, 30 mL of a 3.0 mol/L NaOH solution was added to the Teflon cup, stirred in a paste, and the Teflon cup was sealed in a hydrothermal kettle at 150°. C water treatment 20 small Then, the hydrothermal kettle was naturally cooled to room temperature, and the mixture was filtered under suction. The filter cake was washed with double distilled water until the pH of the filtrate was 9, and the filter cake was dried in an air atmosphere at 80 ° C for 6 hours to obtain a layered dioxide. Manganese solid powder;

Weigh 2.0 g of the layered manganese dioxide solid powder obtained above into 200 mL of a 1.5 mol/L HNO ₃ solution, and stir the reaction at room temperature for 5 days, during which a new 1.5 mol/L HNO was replaced every 24 hours. ₃ solution; the mixture was suction filtered, washed with double distilled water until the filtrate pH value of 7, the filter cake was dried in an air atmosphere of 80 ° C for 6 hours to obtain hydrogen exchange layered manganese dioxide;

Measure 18 mL of 25% by mass of tetramethylammonium hydroxide, add to 21 lmL of secondary distilled water to form a solution, and weigh 1.lg of the hydrogen exchange layered manganese dioxide obtained above to be dispersed to the above tetramethylhydrogen In the ammonium oxide solution, the reaction was stirred at room temperature for 10 days. The mixture was centrifuged at 10,000 rpm for 15 minutes, washed twice with 400 mL of secondary distilled water, centrifuged, and the precipitate was subjected to X-ray diffraction analysis. The XRD pattern showed a layer of hydrogen exchange layered manganese dioxide. The diffraction peak of the structural characteristic disappeared, and it was confirmed that the negatively charged manganese dioxide stripped nanosheet of the laminate was obtained.

The layer of negatively charged manganese dioxide nanosheets was added with water to prepare a 0.10 g/L manganese dioxide nanosheet sol.

b. Preparation of positively charged magnesium aluminum hydrotalcite nanosheets:

Take O.lmol of Mg(NO ₃ ) 6H ₂ O and 0.05 mol of Α1(ΝΟ ₃ ) ₃ ·9Η ₂ Ο, dissolved in de-CO ₂ in twice distilled water under the protection of Ν _{2 to} prepare the total concentration of metal ions. It is a mixed salt solution of 1.5 mol/L; 0.2 mol of NaOH is dissolved in a secondary distilled water of CO ₂ under N ₂ protection to prepare an alkali solution having a concentration of 2.0 mol/L; 0.05 mol of glycine is taken. Dissolved in a double distilled water deCO ₂ under a protection of 3⁄4, and formulated into a 500 mL aqueous solution of glycine having a concentration of 0.1 mol/L;

The mixed salt solution and the alkali solution are simultaneously dropped into the glycine aqueous solution under the protection of N ₂ , and the dropping rate of the NaOH solution is controlled during the dropwise addition and stirred to maintain the pH of the system at about 12 to obtain a slurry; the resulting slurry under N ₂ at 90 ° C crystallization for 3 hours and cooled to room temperature, washed twice with distilled water removal of CO _2, filtered, and the filter cake was dried in vacuo at room temperature for 12 hours to give magnesium aluminum hydrotalcite intercalated glycine Powder

0.50 g of the glycine intercalated magnesium aluminum hydrotalcite powder obtained above was added to 100 mL of the formamide solution, and the reaction was stirred for 3 hours to obtain a clear and transparent sol; 2 drops of the sol were dropped on the frosted glass sheet for X-ray diffraction analysis, XRD pattern The layered structure showing the glycine intercalated magnesium aluminum hydrotalcite disappeared, and it was confirmed A layer of positively charged magnesium aluminum hydrotalcite stripped nanosheets.

The clear transparent sol of the magnesium aluminum hydrotalcite nanosheet obtained above was added with water to prepare a 0.10 g/L magnesium aluminum hydrotalcite nanosheet sol.

c. Cleaning and activation of single crystal silicon substrate:

The single crystal silicon substrate was immersed in methanol and concentrated hydrochloric acid (hydrogen sulfate content: 37%). The ultrasonic solution was washed in a washing solution prepared by volume ratio of 1:1 for 30 minutes, and then immersed in concentrated sulfuric acid (sulfuric acid mass fraction: 98%). After washing for 30 minutes, it was finally rinsed with a large amount of double distilled water and then dried with N ₂ . The cleaned single crystal silicon substrate was further immersed in an aqueous solution of 1.5 g/L of branched polyvinylamine (PEI) for 15 minutes, taken out, and blown dry with N _{2 to} obtain a positively charged single crystal silicon substrate.

d. Preparation of manganese dioxide/magnesium aluminum hydrotalcite inorganic nanosheet composite film:

The positively charged single crystal silicon substrate was immersed in a 0.10 g/L manganese dioxide nanosheet sol at room temperature in an air atmosphere, taken out after 30 minutes, rinsed with double distilled water, dried under N ₂ , and then dried. The substrate was immersed in a 0.10 g/L magnesium aluminum hydrotalcite nanosheet sol, taken out after 30 minutes, rinsed with double distilled water, and dried by N _{2 to} complete a layer of manganese dioxide/magnesium aluminum hydrotalcite nanosheet composite film. preparation. Repeat the above operation as a multi-layer manganese dioxide/magnesium aluminum hydrotalcite inorganic nanosheet composite film.

X-ray diffraction analysis was used to characterize the structure of the different layer films of this example (see Fig. 5). The characteristic diffraction peak intensity at 2° showed a good linear relationship with the number of assembled layers, indicating that the inorganic nanosheet composite of this example The assembly process of the film is continuous and uniform.

The ultraviolet absorption properties of the composite film in this example were tested by an ultraviolet-visible spectrophotometer. The results show that the inorganic nanosheet composite film has a broad ultraviolet absorption peak at 380 nm and has a wide ultraviolet region of 200 to 400 nm. Good UV absorption properties, can be used as UV shielding film materials. In addition, since the magnesium aluminum hydrotalcite is a solid base catalyst with excellent performance, the manganese dioxide nanosheet has good electrical conductivity and ultraviolet absorption property, so the manganese dioxide/magnesium aluminum hydrotalcite inorganic nanosheet composite film of the embodiment It has application value in the field of photoelectric catalysis. Example 3: Manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film and preparation method thereof a. Preparation of negatively charged manganese dioxide nanosheets with laminate:

200 mL of a mixed solution containing 0.6 mol/L NaOH and 1.2 mol/L H ₂ O ₂ was added to 100 mL of a solution containing 0.3 mol/L Mn(NO 3 ) ₂ , stirred for 30 minutes, filtered, and the filter cake was transferred to 100 mL of poly In the tetrafluoroethylene cup; add 30 mL of a 2.0 mol/L NaOH solution to the Teflon cup, stir it into a paste, and seal the Teflon cup in a hydrothermal kettle at 150 ° C. After hydrothermal treatment for 20 hours; then the hydrothermal kettle was naturally cooled to room temperature, and the mixture was suction filtered, and the filter cake was washed with double distilled water until the pH of the filtrate was 9, and the cake was dried in an air atmosphere at 80 ° C for 8 hours to obtain a layer. Manganese dioxide solid powder;

2.18 g of the layered manganese dioxide solid powder obtained above was weighed and added to 300 mL of a 1.25 mol/L HNO ₃ solution, and stirred at room temperature for 4 days, during which a new 1.25 mol/L HNO3 was replaced every 24 hours. Solution; the mixture was suction filtered, washed with double distilled water until the pH of the filtrate was 7, and the filter cake was dried in an air atmosphere at 80 ° for 6 hours to obtain a hydrogen exchange layered manganese dioxide;

Measure 18 mL of 4% by mass of tetramethylammonium hydroxide, add to 200 mL of twice-distilled water to prepare a solution, and weigh 1.lg of the hydrogen exchange layered manganese dioxide obtained above, and disperse it in the above four In the ammonium hydroxide solution, the reaction was stirred at room temperature for 7 days; the mixture was centrifuged at 10,000 rpm for 10 minutes, washed twice with 400 mL of secondary distilled water, centrifuged, and the precipitate was subjected to X-ray diffraction analysis. The XRD spectrum shows that the diffraction peaks of the layered structure of the hydrogen exchange layered manganese dioxide disappeared, and it was confirmed that the negatively charged manganese dioxide stripped nanosheets were obtained.

The layer of negatively charged manganese dioxide nanosheets was added with water to prepare a 0.40 g/L manganese dioxide nanosheet sol.

b. Preparation of positively charged nickel-aluminum hydrotalcite nanosheets:

Take 0.075 mol of Μ(ΝΟ ₃ ) ₂ ·6Η ₂ Ο and 0.025 mol of Α1(ΝΟ ₃ ) ₃ ·9Η ₂ Ο, dissolved in de-CO ₂ in double distilled water under the protection of Ν _{2 to} prepare total metal ions a mixed salt solution having a concentration of 1.0 mol/L; taking O.lmol of NaOH, dissolved in a secondary distilled water of CO ₂ under N ₂ protection, and preparing an alkali solution having a concentration of 0.5 mol/L; Lmol of glycine, dissolved in double distilled water de CO ₂ under the protection of 3⁄4, formulated into a concentration of 0.2mol / L of glycine aqueous solution 500mL;

The mixed salt solution and the alkali solution are simultaneously dropped into the glycine aqueous solution under the protection of N ₂ to obtain a slurry, and the dropping rate of the NaOH solution is controlled during the dropwise addition and stirred to maintain the pH of the system at 10; slurry under N ₂ at 60 ° C crystallization 24 hours, cooled to room temperature, washed twice with distilled water removal of CO _2, filtered, and the filter cake was dried in vacuo at room temperature for 18 hours to give the glycine water intercalated nickel-aluminum talc body;

0.50 g of the glycine intercalated nickel aluminum hydrotalcite powder obtained above was added to 100 mL of a formamide solution The reaction was stirred for 2 hours to obtain a clear and transparent sol; a drop of sol was dropped on a frosted glass sheet for X-ray diffraction analysis, and the XRD pattern showed that the diffraction peak of the layered structure characteristic of the glycine intercalated nickel-aluminum hydrotalcite disappeared, and it was confirmed that A layer of positively charged nickel aluminum hydrotalcite stripped nanosheets.

The clear transparent sol of the nickel-aluminum hydrotalcite nanosheet obtained above was added with water to prepare a nickel-aluminum hydrotalcite nanoplate sol of 0.40 g/L.

c. The process of cleaning and activating the single crystal silicon substrate to have a positive charge is the same as in Example 2. d. Preparation of manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film:

The positively charged single crystal silicon substrate was immersed in a 0.40 g/L manganese dioxide nanosheet sol at room temperature in an air atmosphere, taken out after 10 minutes, rinsed with double distilled water, dried under N ₂ , and then dried. The substrate was immersed in a 0.40 g/L nickel-aluminum hydrotalcite nanosheet sol, taken out after 10 minutes, rinsed with double distilled water, and blown dry to complete the preparation of a layer of manganese dioxide/nickel aluminum hydrotalcite nanosheet composite film. . The above operation is repeated, that is, a multi-layer manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film.

The structure of the composite film of this example was characterized by X-ray diffraction analysis, and the characteristic diffraction peak intensity showed a good linear relationship with the number of the assembled layers, indicating that the assembly process of the inorganic nanosheet composite film was continuous and uniform.

The ultraviolet absorption properties of the composite film in this example were tested by an ultraviolet-visible spectrophotometer. The results show that the inorganic nanosheet composite film has a broad ultraviolet absorption peak at 380 nm and has a wide ultraviolet region of 200 to 400 nm. Good UV absorption properties, can be used as UV shielding film materials. In addition, the manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film of the invention has application value in the field of photoelectric conversion by utilizing the synergistic effect between the ultraviolet absorption performance of the manganese dioxide nanosheet and the electrochemical performance of the nickel aluminum hydrotalcite. Example 4: Manganese dioxide / cobalt aluminum hydrotalcite inorganic nanosheet composite film and preparation method thereof A. The preparation method of the negatively charged manganese dioxide nanosheet of the laminate is the same as in the second embodiment. The obtained negatively charged manganese dioxide nanosheets were added with water to prepare a 0.20 g/L manganese dioxide nanoplate sol.

b. Preparation of positively charged cobalt aluminum hydrotalcite nanosheets:

Take 0.075mol the _{_{_{Co (NO 3) 2 -6H 2}}} O and 0.025mol of _{_{Α1 (ΝΟ 3) 3 · 9Η}} 2 Ο, v ₂ in the de-protection was dissolved in CO ₂ in double distilled water to prepare a total metal ion a mixed salt solution having a concentration of 1.0 mol/L; taking 0.1 mol of NaOH, dissolved in a secondary distilled water of CO ₂ under N ₂ protection, and preparing an alkali solution having a concentration of 1.0 mol/L; taking 0.05 mol glycine, protected at ¾ was dissolved in double distilled off CO ₂ Medium, formulated into a concentration of 0.1mol / L of glycine aqueous solution 500mL;

The mixed salt solution and the alkali solution are simultaneously dropped into the glycine aqueous solution under the protection of N ₂ , and the dropping rate of the NaOH solution is controlled during the dropwise addition and stirred to maintain the pH of the system at 9, to obtain a slurry; the slurry under N ₂ at 80 ° C crystallization 24 hours, cooled to room temperature, washed twice with distilled water removal of CO _2, filtered, and the filter cake was dried in vacuo at room temperature for 12 hours to give glycine cobalt aluminum hydrotalcite intercalated Powder

0.40 g of the glycine intercalated cobalt aluminum hydrotalcite powder obtained above was added to 100 mL of the formamide solution, and the reaction was stirred for 2 hours to obtain a clear and transparent sol; 1 drop of the sol was dropped on the frosted glass piece for X-ray diffraction analysis, XRD spectrum The diffraction peaks of the layered structure characteristic of the glycine-intercalated cobalt-aluminum hydrotalcite disappeared, and it was confirmed that the cobalt-aluminum hydrotalcite-peeled nanosheet with positive charge was obtained.

The clarified transparent sol of the cobalt aluminum hydrotalcite nanosheet obtained above was added with water to prepare a 0.20 g/L cobalt aluminum hydrotalcite nanosheet sol.

c. The process of cleaning and activating the quartz substrate to obtain a positively charged quartz substrate is the same as in Example 1.

d. Preparation of manganese dioxide/cobalt aluminum hydrotalcite inorganic nanosheet composite film:

The positively charged quartz substrate was immersed in a 0.20 g/L manganese dioxide nanosheet sol at room temperature in an air atmosphere, taken out after 20 minutes, rinsed with double distilled water, N ₂ dried, and then the substrate was dried. It was immersed in a 0.20 g/L cobalt aluminum hydrotalcite nanosheet sol, taken out after 20 minutes, rinsed with double distilled water, and dried by N _{2 to} complete the preparation of a layer of manganese dioxide/cobalt aluminum hydrotalcite nanosheet composite film. Repeat the above operation as a multi-layer manganese dioxide/cobalt aluminum hydrotalcite inorganic nanosheet composite film.

The ultraviolet absorption properties of the composite film in this example were tested by an ultraviolet-visible spectrophotometer. The results show that the inorganic nanosheet composite film has a broad ultraviolet absorption peak at 380 nm and has a wide ultraviolet region of 200 to 400 nm. Good UV absorption properties, can be used as UV shielding film materials. In addition, since the cobalt aluminum hydrotalcite has good electrochemical properties, the manganese dioxide/cobalt aluminum hydrotalcite inorganic nanosheet composite film of the present embodiment can be used as an electrode material for an alkaline battery or a supercapacitor, and is used for photoelectric conversion and Photoelectric catalysis and other fields have application value. Example 5: Manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film and preparation method thereof: a. Preparation of negatively charged manganese dioxide nanosheets and preparation of 0.20 g/L manganese dioxide nanosheets The method of the sol was the same as in Example 1.

b. The preparation method of the nickel-aluminum hydrotalcite nanosheet with a positive charge on the laminate is the same as in the third embodiment. The clarified transparent sol of the obtained nickel-aluminum hydrotalcite nanosheet was added with water to prepare a 0.20 g/L nickel aluminum hydrotalcite nanosheet sol.

c. Cleaning and activation of indium tin oxide (ITO) conductive glass substrates:

The indium tin oxide (ITO) conductive glass substrate was ultrasonically washed with acetone, absolute ethanol and double distilled water for 20 minutes, and then immersed in an aqueous H ₂ O ₂ solution (H ₂ O ₂ mass fraction of 30%). Ammonia water (ammonium mass fraction of 28%) and double distilled water were ultrasonically cleaned in a washing solution prepared at a volume ratio of 1:1:5 until no bubbles were generated, and finally rinsed with a large amount of secondary distilled water, and then dried with N ₂ . The cleaned indium tin oxide (ITO) conductive glass substrate was immersed in an aqueous solution of 1.25 g/L branched polyvinylamine (PEI) for 20 minutes, taken out, and dried by N _{2 to} obtain a positively charged indium tin oxide. (ITO) Conductive glass substrate.

d. Preparation of manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film:

A positively charged indium tin oxide (ITO) conductive glass substrate was immersed in an aqueous solution of 0.20 g/L of manganese dioxide nanosheet at room temperature in an air atmosphere, taken out after 20 minutes, rinsed with double distilled water, and blown Dry, then immerse the substrate in 0.20g / L aqueous solution of nickel aluminum hydrotalcite nanosheet, take it out after 20 minutes, rinse it with double distilled water, blow dry N ₂ , complete a layer of manganese dioxide / nickel aluminum hydrotalcite nanosheet Preparation of composite films. The above operation is repeated, that is, a multi-layer manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film.

The ultraviolet absorption properties of the composite film in this example were tested by an ultraviolet-visible spectrophotometer. The results show that the inorganic nanosheet composite film has a broad ultraviolet absorption peak at 380 nm and has a wide ultraviolet region of 200 to 400 nm. Good UV absorption properties, can be used as UV shielding film materials.

In this embodiment, 10 layers (m=10) of manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet composite film were assembled on the indium tin oxide (ITO) conductive glass substrate as the working electrode, and the Hg/HgO electrode was used as the reference electrode. Large-area platinum wire is used as auxiliary electrode, lmol/L NaOH aqueous solution is used as electrolyte, assembled into three-electrode test system, and cyclic voltammetry test is carried out by ZMHNER's IM6e electrochemical workstation in Germany. The potential scanning range is 0.0~0.6V (vs Hg/HgO), scan rate lmV^ Electrochemical test results are shown in Figure 6. There is a reversible redox peak in the range of 0.4 to 0.5 V (vs. Hg/HgO), indicating that the inorganic nanosheet composite film can be used as a positive electrode material for an alkaline secondary battery. The oxidation peak potential (E ₀ ) is 0.470V, the reduction peak potential (E _R ) is 0.416V, ΔΕ _Ρ = Ε ₀ - E _R = 0.054V, which is much smaller than the ΔΕ _ρ value of the general nickel hydroxide electrode material of about 0.1V. , indicating that the electrode material has good reversibility; the oxidation peak and the oxygen evolution peak (E _QE ) are relatively open, which is beneficial to the oxidation of the film electrode, thereby improving the charging current efficiency. Changing the number of layers of the manganese dioxide/nickel aluminum hydrotalcite inorganic nanosheet double layer (ie, changing the m value), and its oxidation peak potential Ε ₀ ,

There was no significant change in the oxygen evolution peak potential E _C)E , but the peak current increased with the increase of the number of assembled layers. Example 6: Manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film

a. The preparation method of the negatively charged manganese dioxide nanosheet of the laminate is the same as in the third embodiment. The obtained negatively-charged manganese dioxide nanosheets were added with water to prepare a 0.02 g/L manganese dioxide nanoplate sol.

b. The method for preparing a positively charged zinc aluminum hydrotalcite nanosheet is the same as in the first embodiment. The clarified transparent sol of the obtained zinc-aluminum hydrotalcite nanosheet was added with water to prepare a 0.02 g/L zinc-aluminum hydrotalcite nanosheet sol.

c. The process of cleaning and activating a single crystal silicon substrate to obtain a positively charged single crystal silicon substrate is the same as in Embodiment 2.

d. The positively charged single crystal silicon substrate was immersed in a 0.02 g/L manganese dioxide nanosheet sol at room temperature in an air atmosphere, taken out after 15 minutes, rinsed with double distilled water, and dried under N ₂ . The substrate was immersed in a 0.02 g/L zinc-aluminum hydrotalcite nanosheet sol, taken out after 15 minutes, rinsed with double distilled water, and blown dry to complete a layer of manganese dioxide/zinc-aluminum hydrotalcite nanosheet composite film. Preparation. Repeat the above operation as a multi-layer manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film.

The ultraviolet absorption properties of the composite film in this example were tested by an ultraviolet-visible spectrophotometer. The results show that the inorganic nanosheet composite film has a broad ultraviolet absorption peak at 380 nm and has a wide ultraviolet region of 200 to 400 nm. Good UV absorption properties, can be used as UV shielding film materials. In addition, since the zinc-aluminum hydrotalcite has good biocompatibility, the manganese dioxide/zinc-aluminum hydrotalcite inorganic nanosheet composite film of the invention has application value in the field of electrochemical biosensors, and can be used as an electrochemical biosensor. Electrode material.

Claims

Claim

1. A manganese dioxide/hydrotalcite inorganic nanosheet composite film, wherein the chemical composition of the inorganic nanosheet composite film is (ns-MnO ₂ /ns-LDHs) _m , wherein ns-MnO ₂ is negative for the laminate Charged manganese dioxide nanosheets, ns-LDHs are layered positively charged hydrotalcite nanosheets, m is the number of layers of the composite film, m^l.

The film according to claim 1, wherein the film has a thickness of 2 to 100 nm, and the number of layers of the composite film is l m 30.

3. The film according to claim 1, wherein the chemical composition of the manganese dioxide nanosheet is

Μη ³⁺ and Μη ⁴⁺ represent manganese ions of +3 valence and +4 valence, respectively, δ and l-δ are the fractions of the substances of +3 valence and +4 valence manganese ions, respectively, δ- is the manganese dioxide nanosheet The negative charge; the manganese octahedron forms a sheet-like structure by co-edge, the sheet structure has a thickness of 0.6 to 10 nm, and a length and a width of 50 to 300 nm.

The film according to claim 1 or 2 or 3, wherein the chemical composition of the hydrotalcite nanosheet is [MS+LpMS+p OH ^ M ²⁺ represents +2 valent metal ion Mg ²⁺ , Zn ^{2 One of +} , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ ; M ³⁺ represents +3 valent metal ions Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ And one of Ti ³⁺ ; l-β and β are the fractions of the substance of the +2 valence and the +3 valent metal ion, respectively, and 0.2 β 0.4; β+ is a positive charge of the hydrotalcite nanosheet; And the hydroxide ions form a octahedron by covalent bonding, and form a sheet structure by co-edge, the sheet structure has a thickness of 0.6 to 5 nm, and a length and a width of 50 to 500 nm.

The film according to claim 4, wherein the M ²⁺ represents Mg ²⁺ .

6. The film according to claim 4, wherein the M ³⁺ represents Al ³⁺ .

7. A method of preparing a manganese dioxide/hydrotalcite inorganic nanosheet composite film according to claim 1, the method comprising the steps of:

Taking a cleaned substrate, immersing in 1.0~1.5g / L branched polyethyleneamine aqueous solution for 15~30 minutes, taking out, drying with N _{2 to} obtain a positively charged substrate;

The positively charged substrate is immersed in a manganese dioxide nanosheet sol having a concentration of negatively charged manganese dioxide nanosheets of 0.01 to 0.40 g/L for 10 to 30 minutes, and then taken out, and rinsed with distilled water. Re-infiltrated into the hydrotalcite nanosheet sol with a concentration of positively charged hydrotalcite nanosheets of 0.01~0.40g/L. After 10 to 30 minutes, take it out and rinse it with distilled water to complete the preparation of a layer of manganese dioxide/hydrotalcite nanosheet composite film. Repeat the above steps to prepare a multilayer manganese dioxide/hydrotalcite inorganic nanosheet composite film.

8. The method according to claim 7, further comprising the step of preparing the layer of negatively charged manganese dioxide nanosheets to prepare the concentration of manganese dioxide nanosheet sol according to the following steps: The ratio of the amount of Mn ^{2+ to the} substance is 3:1 to 4:1, and the ratio of the amount of H ₂ O ₂ to Mn ²⁺ is 6:1 to 8:1, which will contain 0.6 to 0.8 mol/L of NaOH and 1.0~. A mixed solution of 1.5 mol/L H ₂ O ₂ is added to 0.3~0.4 mol/L of Mn (NO ₃ ;> ₂ solution, stirred for 20 to 30 minutes, filtered, and the filter cake is collected; and according to ΟΗ· and ΜηΟ ₂ substances The ratio of 2:1 to 4:1 is added to the filter cake with a concentration of 2.0~3.0mol/L NaOH solution, stirred in a paste, hydrothermally treated at 150~160 °C for 15~20 hours; then naturally cooled to room temperature. , suction filtration, washing the filter cake with distilled water until the pH of the filtrate is 8~9, and drying the filter cake in an air atmosphere of 70-80 ° C for 6 to 9 hours to obtain layered manganese dioxide;

According to the ratio of H+ to layered manganese dioxide, the ratio of 10:1 to 15:1, the above layered manganese dioxide is added to the HNO ₃ solution at a concentration of 1.0 to 1.5 mol/L, and the reaction is stirred at room temperature for 3 to 5 days. In the meantime, a new HNO ₃ solution with a concentration of 1.0~1.5mol/L is replaced every 24 hours. After the reaction is finished, the mixture is suction filtered, washed with distilled water until the pH of the filtrate is 6~7, and the filter cake is 70~ Drying in an air atmosphere at 80 ° C for 6 to 9 hours to obtain a hydrogen exchange layered manganese dioxide;

The hydrogen exchange layered manganese dioxide is added to the mass fraction of 1.5% to 2.0% by mass ratio of tetramethylammonium hydroxide to hydrogen exchange layered manganese dioxide. In the aqueous solution of ammonium hydroxide, the reaction was stirred at room temperature for 7 to 10 days, and centrifuged to separate, and the lower layer precipitated was a negatively charged manganese dioxide nanosheet.

9 Process according to claim 7 or claim 8, further comprising said hydrotalcite nano-ply sheet prepared positively charged following steps to formulate the concentrations of hydrotalcite nanosheet sol: the M ² The soluble salt of ^{+ and} the soluble salt of M ³⁺ are dissolved in distilled water according to the ratio of M ²⁺ /M ^{3 +} substance in a ratio of 1.5 to 4, and a mixed salt solution is prepared, wherein the concentration of M ²⁺ is 0.1~ 1.6mol/L;

Dissolving NaOH in distilled water to prepare an alkali solution having a concentration of 0.5 to 2.0 mol/L;

The above two solutions are simultaneously dropped into the glycine aqueous solution under the protection of 3⁄4, wherein the amount of the glycine substance is 1 to 4 times the amount of the M ³⁺ substance, and the pH of the system is maintained during the dropwise addition to 8 to 12 Getting a slurry; The slurry obtained above is crystallized under the protection of N ₂ at 40 to 90 ° C for 2 to 24 hours, washed, filtered, and the filter cake is dried under vacuum at room temperature for 12 to 24 hours to obtain a glycine intercalated hydrotalcite;

According to the ratio of glycine intercalated hydrotalcite mass/formamide volume=l~5g/L, the glycine intercalated hydrotalcite is weighed into the corresponding volume of formamide, and the reaction is stirred for 1~3 hours to obtain a clear and transparent laminar strip. A sol of a positively charged hydrotalcite nanosheet.

10. The method according to claim 9, wherein the soluble salt of M ²⁺ is a nitrate, a chloride or a sulfuric acid of Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ²⁺ , Mn ²⁺ . One of the salts, the soluble salt of M ³⁺ is Al ³⁺ , Cr ³⁺ , Fe ³⁺ , V ³⁺ , Co ³⁺ , Ga ³⁺ , Ti ³⁺ nitrate, chloride or One of the sulfates.

The method according to claim 7, wherein the substrate is a quartz substrate, a single crystal silicon substrate or an indium tin oxide conductive glass substrate.

12. The method according to claim 11, wherein

The quartz substrate is a substrate cleaned by the following steps: The quartz substrate is ultrasonically washed with acetone, absolute ethanol and distilled water for 20 to 30 minutes, and then immersed in a mass fraction of 30% to 33%. ₂ O ₂ aqueous solution and concentrated sulfuric acid with a mass fraction of 95%~98% are ultrasonically cleaned in a washing solution prepared at a volume ratio of 3:7, and then immersed in an aqueous solution of H ₂ O _{2 having a} mass fraction of 30% to 33%, quality The concentrated ammonia water and distilled water with a fraction of 25%~28% are ultrasonically cleaned in a washing solution prepared by volume ratio of 1:1:5, and finally rinsed with distilled water, and then dried by 3⁄4;

The single crystal silicon substrate is a substrate cleaned by the following steps: ultrasonic cleaning of a single crystal silicon substrate with a methanol and a mass fraction of 36% to 38% concentrated hydrochloric acid in a volume ratio of 1:1. After 20~30 minutes, ultrasonic cleaning with concentrated sulfuric acid with a mass fraction of 95%~98% for 20~30 minutes, finally rinsed with distilled water, and then dried with N ₂ ;

The indium tin oxide conductive glass substrate is a substrate cleaned by the following steps: the indium tin oxide conductive glass substrate is ultrasonically washed successively with acetone, absolute ethanol and distilled water for 20 to 30 minutes, and then immersed in a mass fraction. Ultrasonic cleaning of 30%~33% H ₂ O ₂ aqueous solution, concentrated ammonia and distilled water with a mass fraction of 25%~28% in a volume ratio of 1:1:5, and finally rinsed with distilled water. N _{2 is} blown dry.