NANO-TITANATE, NANO-TITANIC ACID, AND NANO-TIO2 CONTAINING DOPING AG, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

The present invention relates to a method for preparing a nano-titanate, a nano-titanic acid and a nano-TiO.sub.2 containing doping E or embedding E nanoparticles, and the use thereof. By using an E-doped Ti-T intermetallic compound as a titanium source, and reacting it with alkaline solution at atmospheric pressure and near its boiling-point temperature, an E-doped titanate nanofilm is prepared with high efficiency and in a short time. Through acid treatment and (or) heat treatment, a titanate nanofilm containing embedding E nanoparticles, an E-doped titanic acid nanofilm, and a titanic acid nanofilm and a TiO.sub.2 flake powder containing embedding E nanoparticles can be further prepared. Through a subsequent reaction at high temperature and pressure, the preparation of an E-doped titanate nanotubes and titanic acid nanotubes, and titanic acid nanotubes and TiO.sub.2 nanotubes/nanorods containing embedding E nanoparticles can be achieved in high efficiency and low-cost.

Claims

1. A method of preparing a titanate nanofilm material doped with E-group elements, comprising the following steps: step 1, providing an initial alloy comprising T-type elements, Ti and E-group elements; wherein the T-type elements comprise at least one of Al and Zn; and the phase composition of the initial alloy comprises a T-Ti intermetallic compound with solid dissolved E-group elements; wherein the atomic percentage content of Ag in the E-group elements is 50%?100%, and the molar ratio of E-group elements to Ti in the initial alloy is 0<C.sub.E/C.sub.Ti?0.25; step 2, reacting the initial alloy with an alkaline solution at a temperature of T.sub.1, during which the reaction interface advances inwardly from the surface of the initial alloy at an average rate of greater than 2 ?m/min, and the initial alloy at the reaction interface undergoes nano-fragmentation through a hydrogen generation and T-removal reaction, and simultaneously undergoes shape and compositional reconfiguration to generate solid flocculent products containing E-group elements; wherein T.sub.1?60? C.; step 3, the temperature of the solid flocculent product containing E-group elements in the reaction system described in step 2 is lowered from T.sub.1 and the solid flocculent product containing E-group elements is collected, i.e., the titanate nanofilm material doped with E-group elements is obtained.

2. A method of preparing a titanate nanofilm material embedded with E nanoparticles, wherein the titanate nanofilm material embedded with E nanoparticles is prepared by heat-treating the product or the titanate nanofilm material doped with E-group elements prepared according to claim 1.

3. A method of preparing a titanic acid nanofilm material doped with E-group elements, wherein the titanic acid nanofilm material doped with E-group elements is obtained by reacting the product or the titanate nanofilm material doped with E-group elements prepared according to claim 1 with an acid solution and then collecting the solid product.

4. A method of preparing a titanic acid nanofilm material embedded with E nanoparticles, wherein the titanic acid nanofilm material embedded with E nanoparticles is prepared by heat-treating the product or the titanic acid nanofilm material doped with E-group elements prepared according to claim 3.

5. A method of preparing a TiO.sub.2 nanosheet powder embedded with E nanoparticles, wherein the TiO.sub.2 nanosheet powder embedded with E nanoparticles is prepared by heat-treating the product or the titanic acid nanofilm material doped with E-group elements prepared according to claim 3.

6. A method of preparing titanate nanotubes doped with E-group elements, comprising the following steps: sealing a solid substance with a alkaline solution in a closed vessel, wherein the solid substance is the product or the titanate nanofilm doped with E-group elements prepared according to claim 1, then the solid substance and the alkaline solution in the closed vessel were treated by a high pressure and a high temperature of T.sub.2 which is higher than that of the T.sub.f solution; wherein the T.sub.f solution is the boiling temperature of the alkali solution involved in the reaction at ambient pressure, and T.sub.f solution<T.sub.2; after a certain time of reaction, the temperature of the closed vessel is lowered and the pressure is restored to ambient pressure, and the final solid product is collected, i.e., the titanate nanotubes doped with E-group elements are obtained.

7. A method of preparing titanate nanotubes embedded with E nanoparticles, wherein the titanate nanotubes embedded with E nanoparticles are prepared by heat-treating the final product or the titanate nanotubes doped with E-group elements prepared according to claim 6.

8. A method of preparing titanic acid nanotubes doped with E-group elements, wherein the titanic acid nanotubes doped with E-group elements are obtained by reacting the final product or the titanate nanotubes doped with E-group elements prepared according to claim 6 with an acid solution and collecting the solid product.

9. A method of preparing titanic acid nanotubes embedded with E nanoparticles, wherein the titanic acid nanotubes embedded with E nanoparticles are prepared by heat-treating the product or the titanic acid nanotubes doped with E-group elements prepared according to claim 8.

10. A method of preparing crystalline TiO.sub.2 nanotubes/rods embedded with E nanoparticles, wherein the crystalline TiO.sub.2 nanotubes/rods embedded with E nanoparticles are prepared by heat-treating the product or the titanic acid nanotubes doped with E-group elements prepared according to claim 8.

11. A titanate nanofilm material doped with E-group elements, which is prepared by a method of preparing a titanate nanofilm material doped with E-group elements prepared according to claim 1, characterized as comprising: the thickness of the titanate nanofilm doped with E-group elements is 0.25 nm?10 nm; the average area of the titanate nanofilm doped with E-group elements is greater than 500 nm.sup.2; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%; the E-group elements is mainly distributed in the titanate nanofilm in the form of atoms or atomic clusters; the phase transition thermal stability of the titanate nanofilm doped with the E-group elements is higher than that of the monolithic titanate nanofilm matrix.

12. A titanate nanofilm material embedded with E nanoparticles, which is prepared by a method of preparing a titanate nanofilm material embedded with E nanoparticles prepared according to claim 2, characterized as comprising: the size of the E nanoparticles is 1.5 nm?10 nm; the E nanoparticles are mainly embedded in the titanate nanofilm; the thickness of the titanate nanofilm with E nanoparticles is 0.3 nm?10 nm; the average area of the titanate nanofilm with E nanoparticles is greater than 400 nm.sup.2; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%4100%.

13. A titanic acid nanofilm material doped with E-group elements, which is prepared by a method of preparing a titanic acid nanofilm material doped with E-group elements prepared according to claim 3, characterized as comprising: the thickness of the titanic acid nanofilm doped with E-group elements is 0.25 nm?10 nm; the average area of the titanic acid nanofilm doped with E-group elements is greater than 500 nm.sup.2; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%; and the E-group elements is mainly distributed in the titanic acid nanofilm in the form of atoms or atomic clusters; the phase transition thermal stability of the titanic acid nanofilm doped with the E-group elements is higher than that of the monolithic titanic acid nanofilm matrix.

14. A titanic acid nanofilm material embedded with E nanoparticles, which is prepared by a method of preparing a titanic acid nanofilm material embedded with E nanoparticles prepared according to claim 4, characterized as comprising: the size of the E nanoparticles is 1.5 nm?10 nm; the E nanoparticles are mainly embedded in the titanic acid nanofilm; the thickness of the titanic acid nanofilm embedded with E nanoparticles is 0.3 nm?10 nm; the average area of the titanic acid nanofilm embedded with E nanoparticles is greater than 400 nm.sup.2; and the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%.

15. A TiO.sub.2 nanosheet powder embedded with E nanoparticles, which is prepared by a method of preparing a TiO.sub.2 nanosheet powder embedded with E nanoparticles prepared according to claim 5, characterized as comprising: the TiO.sub.2 nanosheet embedded with E nanoparticles is in the form of a sheet; the TiO.sub.2 nanosheet embedded with E nanoparticles has a thickness of 1 nm?30 nm; the TiO.sub.2 nanosheet embedded with E nanoparticles has an average area of more than 100 nm.sup.2; the E nanoparticles have a size of 1.5 nm?10 nm; the E nanoparticles are mainly embedded in the TiO.sub.2 nanosheets; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%.

16. A titanate nanotube doped with E-group elements, which is prepared by a method of preparing a titanate nanotube doped with E-group elements prepared according to claim 6, characterized as comprising: the outer diameter of the titanate nanotube doped with E-group elements is 2 nm?20 nm; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%; the E-group elements is mainly distributed in the titanate nanotubes in the form of atoms or atomic clusters; the titanate nanotube doped with E-group elements has a higher phase transition thermal stability than that of the monolithic titanate nanotube matrix.

17. A titanate nanotube embedded with E nanoparticles, which is prepared by a method of preparing a titanate nanotube embedded with E nanoparticles prepared according to claim 7, characterized as comprising: the size of the E nanoparticles is 1.5 nm?10 nm; the E nanoparticles are mainly embedded in the titanate nanotube; the outer diameter of the titanate nanotube embedded with E nanoparticles is 2 nm?20 nm; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; and the atomic percentage content of Ag in the E-group elements is 50%?100%.

18. A titanic acid nanotube doped with E-group elements, which is prepared by a method of preparing a titanic acid nanotube doped with E-group elements prepared according to claim 8, characterized as comprising: the outer diameter of the titanic acid nanotubes doped with E-group elements is 2 nm?20 nm; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; the atomic percentage content of Ag in the E-group elements is 50%?100%; the E-group elements is mainly distributed in the titanic acid nanotubes in the form of atoms or atomic clusters; the titanic acid nanotubes doped with the E-group elements have a higher phase transition thermal stability than that of the monolithic titanic acid nanotube matrix.

19. A titanic acid nanotube embedded with E nanoparticles, which is prepared by a method of preparing a titanic acid nanotube embedded with E nanoparticles prepared according to claim 9, characterized as comprising: the E nanoparticles have a size of 1.5 nm?10 nm; the E nanoparticles are mainly present in titanic acid nanotubes by means of embeddedness; the E nanoparticles are mainly embedded in the titanic acid nanotubes; the titanic acid nanotubes embedded with E nanoparticles have an outer diameter of 2 nm?20 nm; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; and the atomic percentage content of Ag in the E-group elements is 50%?100%.

20. A crystalline TiO.sub.2 nanotube/rod embedded with E nanoparticles, which is prepared by a method of preparing a crystalline TiO.sub.2 nanotube/rod embedded with E nanoparticles prepared according to claim 10, characterized as comprising: the size of the E nanoparticles is 1.5 nm?10 nm; the E nanoparticles are mainly embedded in the crystalline TiO.sub.2 nanotubes/rods; the outer diameter of the TiO.sub.2 nanotubes/rods embedded with E nanoparticles is 2 nm 25 nm; the molar ratio of the E-group elements to Ti satisfies 0<C.sub.E/C.sub.Ti?0.25; and the atomic percentage content of Ag in the E-group elements is 50%?100%.

21. A method of preparing titanate nanotubes doped with E-group elements, which are prepared by the following steps: step 1), providing an initial alloy comprising T-type elements, Ti and E-group elements; wherein the T-type elements comprise at least one of Al and Zn; and the phase composition of the initial alloy comprises a T-Ti intermetallic compound with solid dissolved E-group elements; wherein the atomic percentage content of Ag in the E-group elements is 50%?100%, and the molar ratio of E-group elements solid dissolved in the T-Ti intermetallic compound to Ti in the initial alloy is 0<C.sub.E/C.sub.Ti?0.25; step 2), sealing the initial alloy with the alkaline solution in a closed vessel, and subsequently heating the closed reaction system to the temperature of T.sub.2 and holding it for a certain period of time; wherein 100? C.<T.sub.f solution<T.sub.2; T.sub.f solution is the boiling point temperature of the alkaline solution involved in the reaction at ambient pressure, and the pressure in the reaction vessel at the temperature of T.sub.2 is higher than the ambient pressure; step 3), lowering the temperature of the closed vessel and restoring the pressure to ambient pressure, and collecting the final solid product, i.e., obtaining titanate nanotubes doped with E-group elements.

22. A method of preparing a titanic acid nanotube doped with E-group elements, wherein the titanic acid nanotube doped with E-group elements is obtained by reacting the final product or the titanate nanotubes doped with E-group elements prepared according to claim 21 with an acid solution and collecting the solid product.

23. A method of preparing titanic acid nanotube embedded with E nanoparticles, wherein the titanic acid nanotube embedded with E nanoparticles is prepared by heat-treating the product or the titanic acid nanotube doped with the E-group elements prepared according to claim 22.

24. A method of preparing crystalline TiO.sub.2 nanotubes/rods embedded with E nanoparticles, wherein the crystalline TiO.sub.2 nanotubes/rods embedded with E nanoparticles are prepared by heat-treating the product or the titanic acid nanotube doped with E-group elements prepared according to claim 22.

25. An application of the product materials prepared according to the preparation method described in any one of claims 1-10, or the product materials prepared according to the preparation method described in any one of claims 21-24, or the materials described in any one of claims 11-20, in polymer-based nanocomposites, resin-based composites, ceramic materials, photocatalytic materials, hydrophobic materials, effluent degrading materials, bactericidal coatings, anticorrosive coatings, and marine coatings.

26. An application of the product materials according to claim 3, wherein the Ag-doped titanic acid nanofilm materials prepared according to the method described in claim 3 is mixed with a polymer, and then a composite coating with the Ag-doped titanic acid nanofilm and the polymer is prepared; in the composite coating, the Ag elements are dispersed in the titanate nanofilm by means of atoms or atomic clusters, and the titanic acid nanofilm is dispersed in the polymer; wherein the composite polymer coating can be applied in fields including hydrophobic materials, sewage degradation materials, antiseptic coating materials, coatings for marine equipment and ships.

27. A method of preparing a titanate nanofilm material doped with E-group elements according to claim 1, wherein the methods as described in step 2 for lowering the temperature of the E-doped solid flocculent product in the reaction system from Ti include at least one of dilution by addition of solvent and cooling by filtration.

28. An application of the product materials prepared by the preparation method according to any one of claims 1-10, or the product materials prepared by the preparation method according to any one of claims 21-24, or the materials according to any one of claims 11-20, in home decoration paint, germicidal sprays, and antifouling paints. wherein the titanate nanotubes embedded with E nanoparticles. As a home decoration paint, the Ag-contained product materials or the product materials described above are mixed with the other components of the paint as a paint additive, and applied to the surface of the furniture, the wares, or the wall to achieve an antibacterial effect; As a germicidal spray, the Ag-contained product materials or the product materials described above are mixed with other liquid spray components, and can be sprayed on the surface of furniture, wares, fabrics, and walls to achieve an antibacterial effect; As an antifouling coating, the Ag-contained product materials or the product materials as described above are substituted for the bactericidal antifouling component in the conventional antifouling coating to achieve an antifouling effect.

29. An application of the product materials prepared according to the preparation method described in any one of claims 1-10, or the product materials prepared according to the preparation method described in any one of claims 21-24, or the materials described in any one of claims 11-20, in an antibacterial fabric, wherein the Ag-contained product materials or the materials are dispersed so as to be adhered to or coated on the surface of the fabric or to be mixed and knitted together with the fabric, so that the fabric has an antibacterial and sterilizing effect and capability.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0763] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0764] FIG. 1 shows the low and high magnification TEM photographs of Ag-doped sodium titanate nanofilms in Embodiment 1;

[0765] FIG. 2 shows the TEM photograph of sodium titanate nanofilms embedded with Ag nanoparticles in Embodiment 1;

[0766] FIG. 3 shows the low magnification and high magnification TEM photographs of Ag-doped titanic acid nanofilms in Embodiment 1;

[0767] FIG. 4 shows an elemental distribution of the Ag-doped titanic acid nanofilms in Embodiment 1;

[0768] FIG. 5 shows the low magnification and high magnification TEM photographs of titanic acid nanofilms embedded with Ag nanoparticles in Embodiment 1;

[0769] FIG. 6 shows the low magnification, medium magnification, and high magnification TEM photographs of anatase TiO.sub.2 nanosheet powder embedded with Ag nanoparticles in Embodiment 1;

[0770] FIG. 7 shows the low magnification and high magnification TEM photographs of Ag-doped titanic acid nanofilms in Embodiment 2;

[0771] FIG. 8 shows the low magnification and high magnification TEM photographs of Ag-doped titanic acid nanofilms in Embodiment 9;

[0772] FIG. 9 shows an XRD pattern of the product prepared in Comparative Example 1;

[0773] FIG. 10 shows the XRD pattern of the anatase TiO.sub.2 powder before reaction in Comparative Example 1;

[0774] FIG. 11 shows a low magnification SEM photograph of the product in Comparative Example 2;

[0775] FIG. 12 shows a high magnification SEM photograph of the product in Comparative Example 2;

[0776] FIG. 13 shows the TEM morphology and diffraction spectra of the titanic acid nanofilms without doping elements by heated at 475? C. for 2 h in Comparative Example 3.

DETAILED DESCRIPTION

[0777] Hereinafter, the described technical solutions will be further illustrated by the following specific embodiments:

Embodiment 1

[0778] This embodiment provides a method of preparing of Ag-doped sodium titanate nanofilm material, sodium titanate nanofilm material embedded with Ag nanoparticles, Ag-doped titanic acid nanofilm material, titanic acid nanofilm material embedded with Ag nanoparticles, and TiO.sub.2 nanosheet powder embedded with Ag nanoparticles, and their uses, including the following steps:

[0779] Weighing the metal Ag, Ti and Al raw materials according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percentage), melting to obtain an alloy melt with the composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25; preparing the alloy melt into an initial alloy in the form of ribbons with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compounds containing solid dissolved Ag.

[0780] Under atmospheric pressure, 0.25 g of the above-made Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon was added into 50 ml of aqueous NaOH solution at a concentration of 10 mol/L and a temperature of its boiling point (about 119? C.) with constant stirring. During the reaction with the concentrated alkaline solution, the Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon undergoes nano-fragmentation through intense hydrogen generation and Al-removal reaction, and simultaneously undergoes shape and compositional reconfiguration to produce solid flocculent products diffusely distributed in the alkaline solution.

[0781] The hydrogen generation and Al-removal reaction was finished within 15 s, and the temperature was hold for 2 min to ensure the completion of the reaction, and then 450 ml of room temperature water was rapidly poured into the reaction system under stirring, and the concentration of alkali in the solution was reduced to 1 mol/L within 2 s, and the temperature was reduced to below 45? C.

[0782] The solid flocculent product was separated from the alkaline solution, cleaned, and dried at 280? C. for 10 min, i.e., Ag-doped sodium titanate nanofilm material was obtained, with the thickness of a single film ranging from 0.25 nm to 2 nm, and the average area of the film was larger than 2000 nm.sup.2, which showed the characteristics of an obvious two-dimensional material, as shown the low-magnification and high-magnification TEM images in FIG. 1. Here the Ag element is mainly distributed in the titanate nanofilm as atoms or atomic clusters, and thus it can not be observed by TEM contrast. Although the Ag-doped sodium titanate nanofilms agglomerated together, they did not contain any nanoporous structure or porous skeletal structure in their structure; based on the observation of the agglomerates in FIG. 1, combined with the electron beam penetration of the TEM, it can be found that the thickness of the agglomerates is extremely thin, which suggests that the agglomerates are not structurally stable near-spherical bodies but rather flat aggregates of a large number of films, which were uniformly flattened out on the TEM carbon mesh during the TEM sample preparation process.

[0783] The above Ag-doped sodium titanate nanofilm material was heat-treated at 550? C. for 2 hours, i.e., the sodium titanate nanofilm material embedded with Ag nanoparticles was obtained, with the thickness of a single film in the range of about 0.5 nm?4 nm, the average area of the film being greater than 1000 nm.sup.2, and the size of Ag nanoparticles in the range of 1.5 nm?5 nm. its TEM morphology is shown in FIG. 2. The thermal stability of the sodium titanate nanofilm matrix was greatly improved due to the pinning effect of Ag elements, as detailed in Comparative Example 3.

[0784] The solid flocculent product after separation from the alkaline solution as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added to it, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2 and 5. After 5 min, the solid-liquid separation was carried out, and after being cleaned, and dried at 250? C. for 15 min, i.e., Ag-doped titanic acid nanofilm material was obtained. The thickness of the single film was about 0.25 nm?2 nm, and the average area of the film was larger than 2000 nm.sup.2. The TEM morphology was shown in the low magnification and high magnification photographs of FIG. 3, and the area of the film was larger than 50,000 nm.sup.2. Here the Ag element was mainly distributed as atoms or atomic clusters in the prepared titanic acid nanofilm, as shown in the elemental distribution map of FIG. 4: although the Ag is not visible in the bright-field image, Ag is uniformly distributed in three different regions in the compositional distribution map (for the convenience of characterization, the region where the film disperses small clusters is selected for elemental distribution mapping to obtain the strongest possible differentiated signals from different regions).

[0785] The above Ag-doped titanic acid nanofilm material was heat-treated at 550? C. for 2 hours, and the Ag elements distributed in the prepared titanic acid nanofilm in the form of atoms or atomic clusters were diffused, agglomerated, and grew up to generate Ag nanoparticles embedded in the titanic acid nanofilm, i.e., titanic acid nanofilm material embedded with Ag nanoparticles was obtained, and the thickness of a single film was about 0.5 nm?4 nm, and the average area of the film was greater than 1000 nm.sup.2, and its thickness increased and its area contracted compared with that of the unheated titanic acid nanofilm; the size of the embedded Ag nanoparticles is in the range of 1.5 nm 5 nm, and some of the embedded Ag nanoparticles, in addition to being partially embedded in the film matrix with a portion of the volume, are also partially exposed outside the film matrix with a portion of the volume. The TEM morphology of the resulting titanic acid nanofilm material embedded with Ag nanoparticles is shown in the low-magnification and high-magnification photograph in FIG. 5. The thermal stability of the titanic acid nanofilm matrix was greatly improved due to the pinning effect of the Ag element, as detailed in Comparative Example 3.

[0786] The above Ag-doped titanic acid nanofilm material was heat-treated at 650? C. for 3 hours, i.e., anatase TiO.sub.2 sheet powder embedded with Ag nanoparticles was obtained. With the heat treatment at this temperature, not only the Ag elements distributed as atoms or atomic clusters in the Ag-doped titanic acid nanofilm were diffused, agglomerated, and grew up to generate the embedded Ag nanoparticles, but also the titanic acid film matrix thereof underwent a transformation to anatase TiO.sub.2, and at the same time the morphology underwent a transformation from thin film to sheet; the anatase-type TiO.sub.2 nanosheets had a thickness in the range of 1 nm-15 nm, an average area greater than 500 nm.sup.2, and the size range of the in situ embedded Ag nanoparticles in the anatase TiO.sub.2 nanosheets was 1.5 nm 5 nm, and their TEM morphologies was shown in the low-middle-high magnification images in FIG. 6.

[0787] The rutile TiO.sub.2 sheet powder embedded with Ag nanoparticles was obtained by heat treating the above Ag-doped titanic acid nanofilm material at 950? C. for 2 hours. The rutile TiO.sub.2 nanosheets have a thickness range of 2 nm 25 nm, an average area of more than 300 nm.sup.2, and a size range of Ag nanoparticles of 1.5 nm 5 nm.

[0788] The above Ag-doped titanic acid nanofilm material is mixed with PDMS (polydimethylsiloxane), and then a PDMS composite coating containing the Ag-doped titanic acid nanofilm is obtained according to a coating preparation method. In this coating, Ag is dispersed in the titanic acid nanofilm in the form of atoms or clusters, and the titanic acid nanofilm is dispersed in PDMS, so that the bactericidal properties of Ag and the mechanical strengthening and strong hydrophobic properties of the titanate nanofilm can be utilized to the maximum extent to obtain the PDMS composite coating with excellent mechanical properties, hydrophobic properties and bactericidal properties. This PDMS composite coating material can be applied in fields including hydrophobic materials, wood antiseptic and bactericidal materials, photocatalytic materials, bactericidal coating materials, coatings for offshore equipment and ships.

[0789] Application as a home decoration coating: the Ag-doped titanic acid nanofilm material described above is applied to the surface of furniture, wares, and walls as a coating additive mixed with other components of the coating to achieve an antibacterial effect;

[0790] Application as a germicidal spray: mixing the Ag-doped titanic acid nanofilm material described above with other liquid spray components and spraying them together through a spray carrier on the surface of furniture, wares, fabrics, and walls to achieve an antibacterial effect;

[0791] Application as an antifouling coating: replacing the above-described Ag-doped titanic acid nanofilm material with the bactericidal antifouling component in the conventional antifouling coating to achieve the antifouling effect;

[0792] Application in antimicrobial fabrics: dispersing the above-described Ag-doped titanic acid nanofilm material so that it adheres to or is coated on the surface of fabrics or is mixed and knitted with fabrics, so as to enable the fabrics to possess antibacterial and antiseptic effects and capabilities.

Embodiment 2

[0793] The present embodiment provides a method for preparing an Ag-doped potassium titanate nanofilm material, a potassium titanate nanofilm material embedded with Ag nanoparticles, an Ag-doped titanic acid nanofilm material, a titanic acid nanofilm material embedded with Ag nanoparticles, and a TiO.sub.2 nanosheet powder embedded with Ag nanoparticles, and their uses, including the following steps:

[0794] The raw materials of metal Ag, Ti and Al are weighed according to the ratio of Ag.sub.1Ti.sub.33Al.sub.66 (atomic percent) and melted to obtain an alloy melt with the composition of Ag.sub.1Ti.sub.33Al.sub.66. The alloy melt is prepared into a ribbon-like initial alloy with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.2 intermetallic compounds containing solid dissolved Ag.

[0795] Under atmospheric pressure, 0.25 g of the above-produced Ag.sub.1Ti.sub.33Al.sub.66 initial alloy ribbon was added to 50 ml of aqueous KOH solution at a concentration of 10 mol/L and a temperature of its boiling temperature (about 125? C.) under continuous stirring. The Ag.sub.1Ti.sub.33Al.sub.66 initial alloy ribbon underwent nano-fragmentation through a violent hydrogen generation and Al-removal reaction with the concentrated alkaline solution, and simultaneously generated solid flocculent products diffusely distributed in the alkaline solution through shape and composition reconfiguration.

[0796] The hydrogen generation and Al-removal reaction was completed within 10 s. The temperature was hold for 1 h to confirm the end of the hydrogen generation and Al-removal reaction, and to confirm that the corresponding products could still be obtained by prolonging the holding time; the volume of the solution was maintained at 50 ml by replenishing the evaporated water during the holding time.

[0797] After 1 h, 450 ml of room temperature water was rapidly poured into the reaction system at one time under stirring, and the alkali concentration in the solution was reduced to 1 mol/L within 2 s, and the temperature was reduced to below 45? C.

[0798] The solid flocculent product was separated from the alkaline solution, cleaned, and dried at 150? C. for 10 min, i.e., Ag-doped potassium titanate nanofilm material was obtained, with the thickness of a single film of about 0.25 nm?2 nm, and the average area of the film being larger than 2000 nm.sup.2. Here the Ag element was mainly distributed in the potassium titanate nanofilm in the form of atoms or atomic clusters. Due to the oxidation of Ag during the drying process, such Ag element contains O-bound Ag.

[0799] The solid flocculent product was separated from the alkaline solution, washed, and dried at 250? C. for 30 min to obtain the Ag-doped potassium titanate nanofilm material, with the thickness of a single film of about 0.25 nm?2 nm, and the average area of the film was more than 2,000 nm.sup.2, in which the Ag element was mainly distributed as atoms or atomic clusters in the potassium titanate nanofilm. It is shown that the target products of Ag-doped potassium titanate nanofilms can still be obtained by continuing the holding time for 1 h after the end of the hydrogen generation and Al-removal reaction.

[0800] The above Ag-doped potassium titanate nanofilm material was heat-treated at 550? C. for 1 h. The potassium titanate nanofilm material embedded with Ag nanoparticles was obtained, with the thickness of a single film ranging from about 0.55 nm?4 nm, the average area of the film being greater than 1500 nm.sup.2, and the size of the Ag nanoparticles ranging from 1.5 nm 5 nm.

[0801] The solid flocculent product after separation from the alkaline solution as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added thereto, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2 and 5, and after 5 min, it was separated, cleaned, and dried at 280? C. for 20 min, i.e., the Ag-doped titanic acid nanofilm material was obtained. The thickness of a single film was about 0.25 nm?2 nm, and the average area of the film was greater than 2000 nm.sup.2, Here the Ag element were distributed in the titanic acid nanofilm as atoms or atomic clusters, and its morphology was shown in the low magnification and high magnification images of FIG. 7.

[0802] The Ag-doped titanic acid nanofilm material described above was heat-treated at 500? C. for 5 hours, i.e., the titanic acid nanofilm material embedded with Ag nanoparticles was obtained, and the thickness of a single film was about 0.5 nm?3 nm, and the average area of the film was greater than 1500 nm.sup.2, and the size of the Ag nanoparticles was in the range of 1.5 nm 5 nm; Some of the embedded Ag nanoparticles, in addition to being partially embedded in the film matrix with a portion of the volume, are also partially exposed outside the film matrix with a portion of the volume.

[0803] The Ag-doped titanic acid nanofilm material was heat-treated at 650? C. for 2 hours to obtain anatase TiO.sub.2 nanosheets embedded with Ag nanoparticles. The thickness of the anatase-type TiO.sub.2 nanosheets ranges from 1 nm 15 nm, the average area is greater than 500 nm.sup.2, and the size of the in situ Ag nanoparticles embedded in the anatase-type TiO.sub.2 nanosheets ranges from 1.5 nm 5 nm.

[0804] The rutile-type TiO.sub.2 nanosheets embedded with Ag nanoparticles was obtained by heat treating the above Ag-doped titanic acid nanofilm material at 950? C. for 2 hours. The thickness of the rutile-type TiO.sub.2 nanosheets ranges from 2 nm 25 nm, and the size of the in situ Ag nanoparticles embedded in situ in the rutile-type TiO.sub.2 nanosheets ranges from 1.5 nm 5 nm.

[0805] The Ag-doped titanic acid nanofilm material described above is mixed with a polymer according to a coating preparation method to obtain a composite coating containing polymer and Ag-doped titanic acid nanofilm. The Ag element in the coating is dispersed in the titanic acid nanofilm in the form of atoms or atomic clusters, and the titanic acid nanofilm is dispersed in the polymer composite coating. So that the bactericidal properties of the Ag element, and the mechanically strengthened and strong hydrophobic properties of the titanic acid nanofilm, can be utilized to the maximum extent possible, and to obtain a polymer composite coating with excellent mechanical properties, hydrophobic properties and bactericidal properties. The polymer composite coating material can be applied in the fields of hydrophobic materials, wood anticorrosive and bactericidal materials, photocatalytic materials, bactericidal coating materials, offshore equipment and marine coatings.

Embodiment 3

[0806] This embodiment provides a method of preparing Ag-doped potassium titanate nanofilm material, including the following steps:

[0807] The raw materials of metal Ag, Ti and Al are weighed according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percentage), and melted to obtain an alloy melt with the composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25; The alloy melt is prepared into an initial alloy in the form of ribbons with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compounds containing solid dissolved Ag.

[0808] Under atmospheric pressure, 0.25 g of the above prepared Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon was added into 50 ml of aqueous KOH solution at a concentration of 15 mol/L and a temperature of 60? C. with constant stirring. The Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon underwent nano-fragmentation through a violent hydrogen generation and Al-removal reaction with the concentrated alkaline solution, and simultaneously underwent shape and compositional reconfiguration to generate solid flocculent products diffusely distributed in the alkaline solution.

[0809] The hydrogen generation and Al-removal reaction was completed within 4 min, and the reaction temperature was hold for 2 min to ensure that the reaction was completely finished. Then, the hot alkaline solution containing the solid flocculated products was poured onto five stacked copper meshes with pore sizes of 200 ?m, 20 ?m, 5 ?m, 5 ?m, and 5 ?m, respectively, at an angle of 45? to the horizontal plane, and the solid flocculated products were retained on the five stacked copper meshes, and the alkaline solution was filtered out while the temperature of the solid products was reduced to below 40? C. within 10 s.

[0810] The resulting solid flocculated product was further cleaned and dried at 50? C. for 1 h. The Ag-doped potassium titanate nanofilm material with a yield of more than 60% was obtained, with the thickness of a single film ranging from 0.25 nm?2 nm, and the average area of the film being greater than 2000 nm.sup.2. Here the element Ag was mainly distributed as atoms or atomic clusters in the potassium titanate nanofilm.

Embodiment 4

[0811] The present embodiment provides a method of preparing Ag-doped sodium titanate nanotubes, sodium titanate nanotubes embedded with Ag nanoparticles, Ag-doped titanic acid nanotubes, titanic acid nanotubes embedded with Ag nanoparticles, and TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles, including the following steps:

[0812] The metal Ag, Ti and Al raw materials were weighed according to the ratio of Ag.sub.1.5Ti.sub.24.5Al.sub.74 (atomic percent) and melted to obtain an alloy melt with the composition of Ag.sub.1.5Ti.sub.24.5Al.sub.74. The alloy melt was prepared into a ribbon-like initial alloy with a thickness of ?100 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compounds containing solid dissolved Ag.

[0813] Under atmospheric pressure, 1 g of the above-made Ag.sub.1.5Ti.sub.24.5Al.sub.74 initial alloy ribbon was added into 50 ml of a NaOH aqueous solution at a concentration of 10 mol/L and a temperature of its boiling point (?119? C.) with constant stirring. The initial alloy ribbon of Ag.sub.1.5Ti.sub.24.5Al.sub.74 underwent nano-fragmentation through intense hydrogen generation and Al-removal reaction with the concentrated alkaline solution during the reaction, and simultaneously underwent shape and compositional reconfiguration to produce solid flocculent products diffusely distributed in the alkaline solution.

[0814] The hydrogen generation and Al-removal reaction is completed within 1 min, and then the hot alkaline solution containing the solid flocculated product is sealed in a PTFE-lined reactor, and the reaction system is subsequently heated to 200? C. within 5 min, at which time the pressure in the reactor is higher than atmospheric pressure;

[0815] After holding the reaction vessel at the high temperature of 200? C. and high pressure for 10 min, the reaction vessel was cooled down to ambient temperature in cold water at 20? C. After the reaction vessel is cooled down to ambient temperature, the pressure inside the vessel is restored to atmospheric pressure, and then the solid material inside the reaction vessel is separated from the solution, cleaned, and dried at 250? C. for 10 min, i.e., Ag-doped sodium titanate nanotube material is obtained, with the outer diameter of the tube ranging from 3 nm to 10 nm, and the length of the tube being more than 5 times the outer diameter of the tube. Therein, the element Ag is distributed in the sodium titanate nanotubes as atoms or atomic clusters, and the as-prepared Ag-doped sodium titanate nanotubes have a phase transition thermal stability higher than that of the monolithic sodium titanate nanotube matrix.

[0816] The above Ag-doped sodium titanate nanotubes were heat-treated at 550? C. for 2 hours, i.e., sodium titanate nanotubes embedded with Ag nanoparticles were obtained, whose outer diameter of the tubes was in the range of 3 nm?10 nm, the length of the tubes was more than 5 times the outer diameter of the tubes, and the Ag nanoparticles had a size in the range of 1.5 nm 5 nm, which were distributed in the sodium titanate nanotubes by means of embedded.

[0817] The solid substance after separation from the alkaline solution in the reactor as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added to it, so that the pH value of the mixed solution decreased continuously, and the pH value of the mixed solution was finally controlled between 2 and 4. After 15 min, solid-liquid separation, cleaning, and drying at 250? C. for 15 min were performed, i.e., Ag-doped titanic acid nanotubes were obtained and the outer diameter of the tube ranges from 3 nm to 10 nm, and the length of the tube is more than 5 times the outer diameter of the tube. Wherein, the Ag element is distributed in the titanic acid nanotubes in the form of atoms or atomic clusters, and the phase transition thermal stability of the obtained Ag-doped titanic acid nanotubes is higher than that of the monolithic titanic acid nanotube matrix.

[0818] The above Ag-doped titanic acid nanotubes were heat-treated at 550? C. for 2 h to obtain titanic acid nanotubes embedded with Ag nanoparticles. The size range of the obtained Ag nanoparticles was 1.5 nm?5 nm, which were distributed in the titanic acid nanotubes by means of embedded growth; the outer diameter of the obtained titanic acid nanotubes was 3 nm?10 nm, and the length of the tubes was more than 5 times the outer diameter of the tubes.

[0819] The above Ag-doped titanic acid nanotubes were heat-treated at 650? C. for 2 h to obtain anatase TiO.sub.2 nanotubes embedded with Ag nanoparticles. The Ag nanoparticles have a size range of 1.5 nm?5 nm, which are distributed in anatase TiO.sub.2 nanotubes by means of embedded growth; the anatase TiO.sub.2 nanotubes have an outer diameter of 3 nm?15 nm, and the length of the tubes is more than 5 times the outer diameter of the tubes.

[0820] The Ag-doped titanic acid nanotubes were heat-treated at 950? C. for 2 h to obtain rutile TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles. The Ag nanoparticles have a size range of 1.5 nm?5 nm, which are distributed in the rutile TiO.sub.2 nanotubes/rods by means of embedded growth; the rutile TiO.sub.2 nanotubes/rods have an outer diameter in the range of 5 nm?20 nm, and the length of the tubes/rods is more than 3 times of the outer diameter of the tubes/rods.

Embodiment 5

[0821] The present embodiment provides a method and application for preparing AgAu doped sodium titanate nanofilms, sodium titanate nanofilms containing embedded AgAu nanoparticles, AgAu doped titanic acid nanofilms, titanic acid nanofilms containing embedded AgAu nanoparticles, and nano-TiO.sub.2 sheet powders containing embedded AgAu nanoparticles, including the following steps:

[0822] The raw materials of metal Ag, Au, Ti and Al were weighed according to the ratio of Ag.sub.0.8Au.sub.0.2Ti.sub.24.75Al.sub.74.25 (atomic percent), and an alloy melt with the composition of Ag.sub.0.8Au.sub.0.2Ti.sub.24.75Al.sub.74.25 was obtained by melting. The alloy melt was prepared into a ribbon-like initial alloy with a thickness of ?15 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compounds containing solid dissolved Ag and Au.

[0823] Under atmospheric pressure, 1 g of the as-prepared Ag.sub.0.8Au.sub.0.2Ti.sub.24.75Al.sub.74.25 initial alloy ribbon was added to 50 ml of a NaOH aqueous solution with a concentration of 10 mol/L and a temperature range of 105? C.?119? C. (boiling temperature of alkaline solution) under continuous stirring The Ag.sub.0.8Au.sub.0.2Ti.sub.24.75Al.sub.74.25 initial alloy ribbon underwent nano-fragmentation through a violent hydrogen generation and Al-removal reaction with the concentrated alkaline solution, and simultaneously generated solid flocculent products diffusely distributed in the alkaline solution through shape and composition reconfiguration.

[0824] The hydrogen generation and Al-removal reaction was finished within 10 s, and the reaction temperature was hold for 2 min to ensure the complete completion of the reaction, and then 450 ml of room-temperature water was rapidly poured into the reaction system under stirring, and the concentration of alkali in the solution was reduced to 1 mol/L within 2 s, and the temperature was reduced to below 45? C.

[0825] The solid flocculent product was separated from the solution, cleaned, and dried at 250? C. for 10 min, i.e., AgAu-doped sodium titanate nanofilm material was obtained, with the thickness of a single film of about 0.25 nm?2 nm, and the average area of the film was larger than 2000 nm.sup.2. Here the elements of Ag, Au were mainly distributed in the sodium titanate nanofilm in the form of atoms or atomic clusters; as the pinning effect of the Ag and Au elements, the thermal stability of the sodium titanate nanofilm matrix is greatly improved.

[0826] The above AgAu-doped sodium titanate nanofilm was heat-treated at 600? C. for 0.1 hour, i.e., sodium titanate nanofilm material containing embedded AgAu nanoparticles was obtained, with the thickness of a single film in the range of about 0.5 nm?3 nm, the average area of the film being greater than 1200 nm.sup.2, and the size of AgAu nanoparticles in the range of 1.5 nm 5 nm, which were distributed in the nanofilm by means of embedded growth.

[0827] The solid flocculent material after separation from the alkaline solution as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added therein, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2 and 5. After 4 h, the separation of the solid-liquid mixture, washing and drying at 250? C. for 10 min were carried out, i.e., AgAu doped titanic acid nanofilm was obtained, and a single thin film with a thickness of about 0.25 nm?2 nm, and the average area of the film was greater than 2000 nm.sup.2. Here the elements of Ag and Au were mainly distributed in the titanic acid nanofilm as atoms or atomic clusters; the thermal stability of the titanic acid nanofilm matrix was greatly improved due to the pining effect of the elements of Ag and Au.

[0828] The above AgAu doped titanic acid nanofilm was heat treated at 550? C. for 2 hours, i.e., titanic acid nanofilm material containing embedded AgAu nanoparticles was obtained, and the thickness of the single film was about 0.5 nm?3 nm, and the average area of the film was more than 1500 nm.sup.2, and the size of the AgAu nanoparticles was in the range of 1.5 nm?5 nm, which were distributed in the titanic acid nanofilm by means of embedded growth.

[0829] The above AgAu-doped titanic acid nanofilm was heat-treated at 650? C. for 2 hours to obtain anatase-type nano-TiO.sub.2 sheet powder containing embedded AgAu nanoparticles. The anatase-type nano-TiO.sub.2 sheet has a thickness ranging from 1 nm to 10 nm, and an average area of more than 500 nm.sup.2, and the AgAu nanoparticles have a size of 1.5 nm to 5 nm, which are distributed in the anatase-type nano-TiO.sub.2 sheet by means of embedded growth.

[0830] The above AgAu-doped titanic acid nanofilm was heat-treated at 950? C. for 2 hours to obtain a rutile-type TiO.sub.2 nanosheet powder containing embedded AgAu nanoparticles. The rutile-type nano-TiO.sub.2 sheet has a thickness ranging from 2 nm to 20 nm, and an average area of more than 400 nm.sup.2, and the AgAu nanoparticles have a size ranging from 1.5 nm to 5 nm, which are distributed in the rutile-type nano-TiO.sub.2 sheet by means of embedded growth.

[0831] The AgAu doped titanic acid nanofilm material was mixed with polyaniline to prepare a composite coating with AgAu doped nano-titanic acid and polyaniline. In this coating, Ag and Au elements are dispersed in the titanic acid nanofilm matrix in the form of atoms or atomic clusters, and the titanic acid nanofilm is dispersed in the polyaniline, which can maximize the utilization of the properties of Ag and Au elements and titanic acid films. The material can be applied in fields including hydrophobic materials, photocatalytic materials, bactericidal coating materials, coatings for offshore equipment and ships.

Embodiment 6

[0832] This embodiment provides a method of preparing AgAuPd doped sodium titanate nanotubes, sodium titanate nanotubes containing embedded AgAuPd nanoparticles, AgAuPd doped titanic acid nanotubes, titanic acid nanotubes containing embedded AgAuPd nanoparticles, and TiO.sub.2 nanotubes/rods containing embedded AgAuPd nanoparticles, including the steps of:

[0833] The raw materials of metal Ag, Au, Pd, Ti and Zn were weighed according to the ratio of Ag.sub.0.8Au.sub.0.1Pd.sub.0.1Ti.sub.24.75Zn.sub.74.25 (atomic percentage), and the alloy melt with the composition of Ag.sub.0.8Au.sub.0.1Pd.sub.0.1Ti.sub.24.75Zn.sub.74.25 was obtained by melting. The alloy melt was solidified into an ingot, and then crushed into a fine alloy powder with a particle size of no more than 100 ?m, which mainly consisted of TiZn.sub.3 intermetallic compounds containing solid dissolved Ag, Au and Pd;

[0834] Under atmospheric pressure, 1 g of the as-prepared Ag.sub.0.8Au.sub.0.1Pd.sub.0.1Ti.sub.24.75Zn.sub.74.25 initial alloy powder was added into 50 ml of a NaOH aqueous solution with a concentration of 15 mol/L and a temperature range of 105? C.?115? C. with constant stirring. The Ag.sub.0.8Au.sub.0.1Pd.sub.0.1Ti.sub.24.75Zn.sub.74.25 initial alloy powder reacted with the concentrated alkaline solution underwent nano-fragmentation through a violent hydrogen generation and Zn-removal reaction with the concentrated alkaline solution, and simultaneously generated solid flocculent products diffusely distributed in the alkaline solution through shape and composition reconfiguration (the solid flocculent product was subsequently separated and dried to obtain the AgAuPd doped sodium titanate nanofilm material).

[0835] The hydrogen generation and Zn-removal reaction was completed within 1 min, and then the hot alkaline solution containing the solid flocculent product described above was sealed in a reactor lined with PTFE, and the reaction system was subsequently heated to 250? C. within 10 min, at which time the pressure in the reactor was higher than atmospheric pressure;

[0836] After holding at 250? C. under high pressure for 10 min, the reactor was placed in cold water for rapid cooling. After the reaction vessel was cooled down to room temperature, the pressure in the vessel was restored to normal pressure, and then the solid material in the reaction vessel was separated from the solution, cleaned, and dried at 250? C. for 10 min, the AgAuPd-doped sodium titanate nanotubes were obtained. The outer diameter of the AgAuPd-doped sodium titanate nanotubes was in the range of 3 nm?12 nm, and the length of which was more than 5 times the outer diameter of the tube. Here the elements Ag, Au, and Pd are distributed in the sodium titanate nanotubes in the form of atoms or atomic clusters, and the as-prepared AgAuPd-doped sodium titanate nanotubes have a phase transition thermal stability higher than that of the monolithic sodium titanate nanotube matrix.

[0837] The AgAuPd-doped sodium titanate nanotubes as described above are heat-treated at 550? C. for 1 h to obtain sodium titanate nanotubes containing embedded AgAuPd nanoparticles, the outer diameter of which is in the range of 3 nm?12 nm, and the length of which is more than 5 times the outer diameter of the tubes. The size of the embedded AgAuPd nanoparticles is 1.5 nm?5 nm, the outer diameter of the sodium titanate nanotube ranges from 3 nm?12 nm, and the embedded AgAuPd nanoparticles are distributed in the sodium titanate nanotube by means of embeddedness.

[0838] The above solid substance after separation from the alkaline solution was dispersed in water, and then 0.025 mol/L HCl solution was gradually added to it, so that the pH value of the mixed solution decreased continuously, and the pH value of the mixed solution was finally controlled between 2?4. After 10 min, separation of the solid-liquid mixture, washing and drying at 250? C. for 10 min were carried out, i.e., The AgAuPd-doped titanic acid nanotubes was obtained; wherein the outer diameter of the tube ranges from 3 nm?12 nm, and the length of the tube is more than 5 times the outer diameter of the tube. Here the elements of Ag, Au and Pd are distributed in the titanic acid nanotubes as atoms or atomic clusters, and the phase transition thermal stability of the obtained the AgAuPd-doped titanic acid nanotubes is higher than that of the monolithic titanic acid nanotube matrix.

[0839] The AgAuPd-doped titanic acid nanotubes as described above were heat-treated at 550? C. for 1.5 h to obtain titanic acid nanotubes containing embedded AgAuPd nanoparticles. The size of the as-prepared embedded AgAuPd nanoparticles is 1.5 nm?5 nm, which is distributed in the titanic acid nanotubes by means of embeddedness, and the outer diameter of the as-prepared titanic acid nanotube matrix is 3 nm?12 nm, and the length of the tubes is more than 5 times the outer diameter of the tubes.

[0840] The AgAuPd-doped titanic acid nanotubes as described above were heat-treated at 650? C. for 2 h to obtain anatase-type TiO.sub.2 nanotubes containing embedded AgAuPd nanoparticles. The AgAuPd nanoparticles have a size of 1.5 nm 5 nm, which are distributed in the anatase-type TiO.sub.2 nanotubes by means of embeddedness, and the anatase-type TiO.sub.2 nanotubes have an outer diameter of 3 nm 15 nm, and the length of the tubes is more than 5 times greater than the outer diameter of the tubes.

[0841] The AgAuPd-doped titanic acid nanotubes as described above were heat-treated at 950? C. for 2 h to obtain rutile-type TiO.sub.2 nanotubes/rods containing embedded AgAuPd nanoparticles. The size of the obtained embedded AgAuPd nanoparticles is 1.5 nm?5 nm, which are distributed in the rutile-type TiO.sub.2 nanotubes/rods by means of embeddedness, and the outer diameter of the rutile-type TiO.sub.2 nanotubes/rods is 3 nm?20 nm and the length of the tubes/rods is greater than more than 3 times of the outer diameter of the tubes/rods.

Embodiment 7

[0842] This embodiment provides a method of preparing Ag-doped sodium (potassium) titanate nanofilm material, sodium (potassium) titanate nanofilm material embedded with Ag nanoparticles, Ag-doped titanic acid nanofilm material, titanic acid nanofilm material embedded with Ag nanoparticles, and TiO.sub.2 sheet powder embedded with Ag nanoparticles, including the following steps:

[0843] The raw materials of metal Ag, Ti and Al were weighed according to the ratio of Ag.sub.1Ti.sub.39Al.sub.60 (atomic percentage), and melt to obtain an alloy melt with a composition of Ag.sub.1Ti.sub.39Al.sub.60. The alloy melt is solidified into an ingot and then crushed to an initial alloy powder with a particle size of no more than 1 mm, which mainly consists of TiAl.sub.2 intermetallic compound containing solid dissolved Ag and TiAl intermetallic compound containing solid dissolved Ag.

[0844] A 15 mol/L KOH solution and a 15 mol/L NaOH solution were prepared respectively, and the two solutions were mixed 1:1 by volume to obtain a mixed KOH and NaOH solution with an OH-concentration of 15 mol/L.

[0845] Under atmospheric pressure, 1 g of the above-produced Ag.sub.1Ti.sub.39Al.sub.60 initial alloy powder was added to 50 ml of a mixed aqueous solution of KOH and NaOH with a concentration of 15 mol/L and a temperature range of 105? C.?115? C. with constant stirring. the Ag.sub.1Ti.sub.39Al.sub.60 initial alloy powder underwent nano-fragmentation through a violent hydrogen generation and Al-removal reaction with the concentrated alkaline solution, and simultaneously generated solid flocculent products diffusely distributed in the alkaline solution through shape and composition reconfiguration.

[0846] The hydrogen generation and Al-removal reaction was finished in close to 8 min, and the reaction temperature was hold for 2 min to ensure the complete completion of the reaction, and then, 700 ml of room-temperature water was rapidly poured into the reaction system under stirring, and the concentration of alkali in the solution was reduced to less than 1 mol/L within 2 s, and the temperature was reduced to less than 45? C.

[0847] The above solid flocculent product was separated from the solution, cleaned, and dried at 250? C. for 10 min, i.e., the Ag-doped sodium (potassium) titanate nanofilm material was obtained, with a thickness of a single film of about 0.25 nm?2 nm, and an average area of a single film of more than 2000 nm.sup.2. Wherein the Ag element was mainly distributed in the sodium (potassium) titanate nanofilm in the form of atoms or atomic clusters. Due to the pinning effect of Ag elements, the thermal stability of the sodium (potassium) titanate nanofilm matrix was greatly improved.

[0848] The above Ag-doped sodium (potassium) titanate nanofilms were heat-treated at 550? C. for 2 hours, i.e., a sodium (potassium) titanate nanoparticle film embedded with Ag nanoparticles was obtained, with the thickness of a single film in the range of about 0.5 nm?3 nm, with the average area of the film being greater than 1000 nm.sup.2, and the size of the embedded Ag nanoparticles in the range of 1.5 nm?5 nm;

[0849] The solid flocculent material after separation from the alkaline solution as described above was dispersed in water, and 0.025 mol/L HCl solution was gradually added therein under stirring, so that the pH value of the mixed solution decreased continuously, and the pH value of the mixed solution was finally controlled between 2 and 5. After 5 min, it was separated, cleaned, and dried at 250? C. for 10 min, i.e., the Ag-doped titanic acid nanofilm was obtained, with a thickness of a single film in the range of about 0.25 nm?2 nm, and an average area of a single film larger than 2000 nm.sup.2. Here the Ag elements were mainly distributed in the titanic acid nanofilm in the form of atoms or atomic clusters; the thermal stability of the titanic acid nanofilm matrix was greatly improved due to the pinning effect of Ag elements.

[0850] The above Ag-doped titanic acid nanofilm was heat-treated at 550? C. for 1.5 hours to obtain a titanic acid nanofilm material embedded with Ag nanoparticles, with a thickness of a single film of about 0.5 nm?3 nm, an average area of the film of more than 1000 nm.sup.2, and a size range of the embedded Ag nanoparticles of 1.5 nm?5 nm;

[0851] The above Ag-doped titanic acid nanofilm was heat-treated at 650? C. for 2 hours to obtain anatase TiO.sub.2 nanosheets embedded with Ag nanoparticles. The anatase TiO.sub.2 nanosheets have a thickness ranging from 1 nm to 15 nm, an average area of more than 400 nm.sup.2, and the Ag nanoparticles in situ embedded in the anatase TiO.sub.2 nanosheets have a size ranging from 1.5 nm to 5 nm.

[0852] The above Ag-doped titanic acid nanofilm was heat-treated at 950? C. for 2 hours, i.e., the rutile TiO.sub.2 sheet powder embedded with Ag nanoparticles was obtained; the thickness of the rutile TiO.sub.2 sheet was in the range of 2 nm?20 nm, with an average area of more than 300 nm.sup.2, and the size of the Ag nanoparticles in situ embedded in the rutile TiO.sub.2 sheet was in the range of 1.5 nm?5 nm.

Embodiment 8

[0853] This embodiment provides a method of preparing Ag-doped sodium (lithium) titanate nanotubes, Ag-doped titanic acid nanotubes, titanic acid nanotubes embedded with Ag nanoparticles, and TiO.sub.2 nanotubes embedded with Ag nanoparticles, including the following steps:

[0854] The raw materials of metal Ag, Ti and Al raw materials were weighed according to the ratio of Ag.sub.3Ti.sub.27Al.sub.70 (atomic percentage), and melt to obtain an alloy melt with the composition of Ag.sub.3Ti.sub.27Al.sub.70, The alloy melt was prepared into an initial alloy ribbon with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compound containing solid dissolved Ag and TiAl.sub.2 intermetallic compound containing solid dissolved Ag.

[0855] A LiOH solution of 6 mol/L and a NaOH solution of 14 mol/L were prepared respectively, and the two solutions were mixed 1:1 by volume to obtain a mixed solution of LiOH and NaOH with OH.sup.? concentration of 10 mol/L.

[0856] Under atmospheric pressure, 1 g of the above-produced initial alloy ribbon was added to 50 ml of the above mixed solution in the temperature range of T.sub.f solution?5? C. to T.sub.f solution with constant stirring. The Ag.sub.3Ti.sub.27Al.sub.70 initial alloy ribbon underwent nano-fragmentation through intense hydrogen generation and Al-removal reaction during the reaction with the concentrated alkaline solution, and was simultaneously reconfigured in shape and composition to generate a solid-state flocculent product that was distributed in alkaline solution.

[0857] The hydrogen generation and Al-removal reaction was completed within 20 s. Then, the hot mixed alkaline solution containing the solid flocculent product as described above was sealed in a reactor lined with PTFE, and the reaction system was subsequently heated to 200? C. within 5 min, at which time the pressure in the reactor was higher than atmospheric pressure;

[0858] After holding at 200? C. for 30 min, the reactor was placed in cold water to cool down rapidly. After the reaction vessel is cooled down to room temperature, the pressure in the vessel is restored to atmospheric pressure, and then the solid material in the reaction vessel is separated from the solution, cleaned, and dried at 280? C. for 10 min, i.e., the Ag-doped sodium (lithium) titanate nanotube material is obtained, with an outer diameter of the tube ranging from 3 nm to 10 nm, and a length of the tube more than 5 times greater than the outer diameter of the tube. Therein, the element Ag is distributed in the sodium (lithium) titanate nanotubes in the form of atoms or atomic clusters, and the as-prepared Ag-doped sodium (lithium) titanate nanotubes have a higher phase transition thermal stability than that of the monolithic sodium (lithium) titanate nanotube matrix.

[0859] The above solid substance after separation from the alkaline solution was dispersed in water, and then 0.025 mol/L HCl solution was gradually added therein, so that the pH value of the mixed solution decreased continuously, and the pH value of the mixed solution was finally controlled between 2?4. After 10 min, solid-liquid separation, cleaning, and drying at 250? C. for 10 min were performed, i.e., the Ag-doped titanic acid nanotubes were obtained. The outer diameter of the tube ranges from 3 nm to 10 nm, and the length of the tube is more than 5 times the outer diameter of the tube. The Ag element is distributed in the titanic acid nanotubes as atoms or atomic clusters, and the phase transition thermal stability of the as-prepared Ag-doped titanic acid nanotubes is higher than that of the nomolithic titanic acid nanotube matrix.

[0860] The above Ag-doped titanic acid nanotubes were heat-treated at 550? C. for 1.5 h, i.e., the titanic acid nanotubes embedded with Ag nanoparticles were obtained; the size of the as-prepared embedded Ag nanoparticles was 1.5 nm-5 nm, which were distributed in the titanic acid nanotubes by means of embeddedness, and the outer diameter of the titanic acid nanotubes was 3 nm?10 nm, and the length of the tubes was more than 5 times greater than the outer diameter of the tubes.

[0861] The above Ag-doped titanic acid nanotubes were heat-treated at 650? C. for 3 h, i.e., the anatase TiO.sub.2 nanotubes embedded with Ag nanoparticles were obtained; the size of the obtained embedded Ag nanoparticles was 1.5 nm 5 nm, which was distributed in anatase TiO.sub.2 nanotubes by means of embeddedness, and the outer diameter of the anatase TiO.sub.2 nanotubes was 3 nm 15 nm, and the length of the tubes was more than 5 times the outer diameter of the tubes.

Embodiment 9

[0862] The present embodiment provides a preparation method of Ag-doped titanate nanofilm material, and Ag-doped titanic acid material, including the following steps:

[0863] The raw materials of metal Ag, Ti and Al were weighed according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percentage), and melt to obtain an alloy melt with the composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25. The alloy melt was prepared into an initial alloy in the form of ribbons with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy ribbons mainly consists of TiAl.sub.3 intermetallic compound containing solid dissolved Ag.

[0864] Under atmospheric pressure, 1 g of the as-prepared Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon was added into 50 ml of aqueous NaOH solution at a concentration of 10 mol/L and a temperature of 105? C.?112? C. with constant stirring. The Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon underwent nano-fragmentation through a violent hydrogen generation and Al-removal reaction with the concentrated alkaline solution, and simultaneously underwent shape and composition reconfiguration to generate a solid flocculent product diffusely distributed in the alkaline solution.

[0865] The hydrogen generation and Al-removal reaction was completed within 15 s. After holding the temperature for 2 hours to confirm the end of the hydrogen generation and Al-removal reaction, the corresponding products could still be obtained by prolonging the holding time; the volume of the solution was maintained at 50 ml by replenishing the evaporated water during the holding time.

[0866] After 2 h, the hot concentrated alkaline solution containing the solid flocculated product was poured onto a four-layer copper mesh with pore sizes of 200 ?m, 20 ?m, 5 ?m, and 5 ?m, respectively, at an angle of 45? to the horizontal plane, the solid flocculated product was retained on the four-layer copper mesh, and the alkaline solution was filtered off, while the temperature of the solid flocculated product was reduced to less than 45? C. in 20 s. The as-prepared solid flocculent product was further cleaned and dried at 250? C. for 10 min to obtain Ag-doped sodium titanate nanofilm material, with the thickness of a single film ranging from 0.25 nm to 2 nm, and the average area of the film being larger than 2000 nm.sup.2. Here the Ag element was mainly distributed as atoms or atomic clusters in the sodium titanate nanofilm matrix.

[0867] The above Ag-doped sodium titanate nanofilm was dispersed in water, and 0.025 mol/L HCl solution was gradually added to it under stirring condition, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2 and 5. After 30 min, it was separated, cleaned, and dried at 250? C. for 10 min, and then the Ag-doped titanic acid nanofilm was obtained. The thickness of a single film is about 0.25 nm?2 nm, and the average area of a single film is larger than 2000 nm.sup.2. Its morphology is shown in the low-magnification and high-magnification images in FIG. 8. It indicates that the target products of the Ag-doped titanic acid nanofilms can still be obtained by continuing the holding time for 2 h after the end of the hydrogen generation and Al-removal reaction, combined with the subsequent acid solution reaction. Here the Ag element in the as-prepared products was mainly distributed in the titanic acid nanofilm matrix as atoms or atomic clusters; due to the pinning effect of the Ag element, the thermal stability of the titanic acid nanofilm matrix was greatly improved.

Embodiment 10

[0868] This embodiment provides a method of preparing Ag-doped titanate nanotubes, Ag-doped titanic acid nanotubes, titanic acid nanotubes embedded with Ag nanoparticles, and TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles, including the following steps:

[0869] The raw materials of metal Ag, Ti and Al were weighed according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percent) and melt to obtain an alloy melt with the composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25. The alloy melt is solidified into an ingot, and then the ingot is crushed into an initial alloy powder with a particle size of not more than 50 ?m, which mainly consists of TiAl.sub.3 intermetallic compounds containing solid dissolved Ag.

[0870] At room temperature and pressure, 0.5 g of the above-made initial alloy powder and 50 mL of NaOH aqueous solution with a concentration of 10 mol/L were placed in a sealed reactor lined with PTFE; then the temperature of the sealed reactor and the initial alloy and the NaOH aqueous solution inside it was immediately raised to 250? C. within 10 min, and then hold for 25 min;

[0871] After 25 min, the reactor was placed in cold water to rapidly cool down. After the reaction vessel was cooled down to room temperature, the pressure inside the vessel was restored to normal pressure, and then the solid material inside the reaction vessel was separated from the solution, cleaned, and dried at 250? C. for 10 min, i.e., the Ag-doped sodium titanate nanotubes were obtained, and the outer diameters of the tubes were 3 nm?12 nm, and the length of the tube is more than 5 times the outer diameter of the tube. The Ag element is distributed in the sodium titanate nanotubes as atoms or atomic clusters, and the phase transition thermal stability of the as-prepared Ag-doped sodium titanate nanotubes is higher than that of the monolithic sodium titanate nanotube matrix.

[0872] The above solid substance after separation from the alkaline solution was dispersed in water, and then 0.025 mol/L HCl solution was gradually added therein, so that the pH value of the mixed solution decreased continuously, and the pH value of the mixed solution was finally controlled between 2 and 4. After 10 min, solid-liquid separation, cleaning, and drying at 250? C. for 10 min were performed, i.e., the Ag-doped titanic acid nanotubes were obtained. The outer diameter of the tube ranges from 3 nm to 12 nm, and the length of the tube is more than 5 times the outer diameter of the tube. Here the Ag element is distributed in the titanic acid nanotubes as atoms or atomic clusters, and the phase transition thermal stability of the as-prepared Ag-doped titanic acid nanotubes is higher than that of the monolithic titanic acid nanotube matrix.

[0873] The above Ag-doped titanic acid nanotubes were heat-treated at 550? C. for 2 h to obtain titanic acid nanotubes embedded with Ag nanoparticles. The size of the embedded Ag nanoparticles is 1.5 nm?5 nm, which is distributed in the titanic acid nanotubes by means of embeddedness, and the outer diameter of the titanic acid nanotubes is 3 nm?12 nm, and the length of the tubes is more than 5 times the outer diameter of the tubes.

[0874] The above Ag-doped titanic acid nanotubes were heat-treated at 650? C. for 3 h, i.e., the anatase TiO.sub.2 nanotubes embedded with Ag nanoparticles were obtained; the size of the embedded Ag nanoparticles was 1.5 nm?5 nm, and the embedded Ag nanoparticles was distributed in anatase TiO.sub.2 nanotubes by means of embeddedness, and the outer diameter of the anatase TiO.sub.2 nanotubes was 3 nm?15 nm and the length of the tubes was more than 5 times the outer diameter of the tubes.

[0875] The above Ag-doped titanic acid nanotubes were heat-treated at 950? C. for 2 h, i.e., the rutile TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles were obtained; the size of the embedded Ag nanoparticles was 1.5 nm?5 nm, and they were distributed in rutile TiO.sub.2 nanotubes/rods by means of embeddedness, and the outer diameters of the rutile TiO.sub.2 nanotubes/rods were 4 nm?20 nm. The length of the rutile TiO.sub.2 nanotubes/rods is more than 3 times of the outer diameter of the tubes/rods.

Embodiment 11

[0876] The present embodiment provides a preparing method of an Ag-doped sodium titanate nanofilm material, a sodium titanate nanofilm material embedded with Ag nanoparticles, an Ag-doped titanic acid nanofilm material, a titanic acid nanofilm material embedded with Ag nanoparticles, and a TiO.sub.2 sheet powder embedded with Ag nanoparticles, and the use thereof, including the following steps:

[0877] The raw materials of metal Ag, Ti and Zn are weighed according to the ratio of Ag.sub.0.5Ti.sub.24.5Zn.sub.75 (atomic percent), and an alloy melt with the composition of Ag.sub.0.5Ti.sub.24.5Zn.sub.75 is obtained by melting. The alloy melt was prepared into a ribbon-like initial alloy with a thickness of ?20 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiZn.sub.3 intermetallic compound containing solid dissolved Ag.

[0878] Under atmospheric pressure, 1 g of the above-made Ag.sub.0.5Ti.sub.24.5Zn.sub.75 initial alloy ribbon was added into 50 ml of aqueous NaOH solution at a concentration of 15 mol/L and a temperature of its boiling point (about 140? C.) with constant stirring. The Ag.sub.0.5Ti.sub.24.5Zn.sub.75 initial alloy ribbon underwent nano-fragmentation through a violent hydrogen generation and Zn-removal reaction with the concentrated alkaline solution, and simultaneously underwent shape and compositional reconfiguration to generate a solid flocculent product diffusely distributed in the alkaline solution.

[0879] The hydrogen generation and Zn-removal reaction was completed within 15 s, and the holding time was continued for 2 min to ensure the complete completion of the reaction, and then 700 ml of room-temperature water was rapidly poured into the reaction system at one time under stirring, and the alkali concentration in the solution was lowered to less than 1 mol/L and the temperature was lowered to below 45? C. in 2 s.

[0880] The solid flocculent product was separated from the alkaline solution, cleaned, and dried at 250? C. for 10 min, i.e., the Ag-doped sodium titanate nanofilm material was obtained, and the thickness of its single film was about 0.25 nm?2 nm, and the average area of the film was larger than 2000 nm.sup.2. Here the Ag elements were mainly distributed in the sodium titanate nanofilm in the form of atoms or atomic clusters, and the thermal stability of the sodium titanate nanofilm matrix is greatly improved due to the pinning effect of Ag elements.

[0881] The Ag-doped sodium titanate nanofilm material was heat-treated at 550? C. for 1 h. The sodium titanate nanofilm material embedded with Ag nanoparticles was obtained, and the thickness of a single film was in the range of about 0.5 nm?3 nm, the average area of the film was greater than 1500 nm.sup.2, and the size of the Ag nanoparticles was in the range of 1.5 nm?5 nm.

[0882] The solid flocculent product after separation from the alkaline solution as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added therein, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2 and 5, and after 20 min, it was separated, cleaned, and dried at 280? C. for 10 min, i.e., The Ag doped titanic acid nanofilm was obtained. The thin film material has a thickness of a single film of about 0.25 nm?2 nm, and the average area of the film is greater than 2000 nm.sup.2. wherein the Ag element is mainly distributed in the titanic acid nanofilm in the form of atoms or atomic clusters, and the thermal stability of the titanic acid nanofilm film matrix has been greatly improved due to the pinning effect of the Ag element.

[0883] The Ag-doped titanic acid nanofilm material was heat-treated at 500? C. for 5 hours to obtain a titanic acid nanofilm material embedded with Ag nanoparticles, with a thickness of a single film of about 0.5 nm?3 nm, an average area of the film of more than 1500 nm.sup.2, and a size range of the embedded Ag nanoparticles of 1.5 nm?5 nm.

[0884] The above Ag-doped titanic acid nanofilm material was heat-treated at 650? C. for 2 hours to obtain an anatase TiO.sub.2 nanosheet powder embedded with Ag nanoparticles. The thickness of the anatase TiO.sub.2 nanosheets ranges from 1 nm to 10 nm, the average area thereof is greater than 500 nm.sup.2, and the size of the Ag nanoparticles in situ embedded in the anatase TiO.sub.2 nanosheets is 1.5 nm?nm.

[0885] The rutile TiO.sub.2 nanosheet powder embedded with Ag nanoparticles was obtained by heat treating the above Ag-doped titania acid nanofilm material at 950? C. for 2 hours. The thickness of the rutile TiO.sub.2 nanosheet ranges from 2 nm to 20 nm, its average area is greater than 300 nm.sup.2, and the size of the Ag nanoparticles in situ embedded in the rutile TiO.sub.2 nanosheet is 1.5 nm?5 nm.

[0886] The above Ag-doped titanic acid nanofilm material was mixed with polyvinylidene fluoride (PVDF) to prepare a composite coating containing Ag-doped titanic acid nanofilm and PVDF. In this coating, Ag element is dispersed in the titanic acid nanofilm in the form of atoms or atomic clusters, and the titanic acid nanofilm is dispersed in PVDF, which can maximize the utilization of the properties of Ag element and titanic acid. The material can be applied in fields including hydrophobic materials, photocatalytic materials, bactericidal coating materials, coatings for offshore equipment and ships.

Embodiment 12

[0887] The present embodiment provides a method for preparing Ag-doped sodium titanate nanotubes, Ag-doped titanic acid nanotubes, titanic acid nanotubes embedded with Ag nanoparticles, and TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles, including the following steps:

[0888] At room temperature and pressure, in a sealed reactor lined with polytetrafluoroethylene, the Ag-doped titanate nanofilm material is placed with 50 mL of 10 mol/L aqueous NaOH in a volume ratio of 1:50; then the temperature of the sealed reactor containing the Ag-doped titanate nanofilm material and the aqueous NaOH solution is elevated to 250? C. within 10 min, and then held for 10 min;

[0889] After 10 min, the reactor was placed in cold water to rapidly cool down. After the reaction vessel was cooled down to room temperature, the pressure inside the vessel was restored to normal pressure, and then the solid material inside the reaction vessel was separated from the solution, cleaned, and dried at 250? C. for 10 min, i.e., the Ag-doped sodium titanate nanotubes were obtained, and the outer diameters of the tubes were 3 nm?12 nm.

[0890] The length of the tube is more than 5 times the outer diameter of the tube. Therein, the Ag element is distributed in the sodium titanate nanotubes in the form of atoms or atomic clusters, and the phase transition thermal stability of the as-prepared Ag-doped sodium titanate nanotubes is higher than that of the monolithic sodium titanate nanotube matrix.

[0891] The solid substance after separation from the alkaline solution as described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added thereto, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 2?4. After 60 min, the solid-liquid separation was carried out, followed by being cleaned and dried for 10 min at 250? C., i.e., the Ag-doped titanic acid nanotubes were obtained. The outer diameter of the tubes ranges from 3 nm to 12 nm, and the length of the tube is more than 5 times the outer diameter of the tube. Here the Ag element is distributed in the titanic acid nanotubes as atoms or atomic clusters, and the phase transition thermal stability of the as-prepared Ag-doped titanic acid nanotubes is higher than that of the monolithic titanic acid nanotube matrix.

[0892] The above Ag-doped titanic acid nanotubes were heat-treated at 550? C. for 2 h to obtain titanic acid nanotubes embedded with Ag nanoparticles. The size of the embedded Ag nanoparticles is 1.5 nm 5 nm, which is distributed in the titanic acid nanotubes by means of embeddedness, and the outer diameter of the titanic acid nanotubes is 3 nm?12 nm, and the length of the tubes is more than 5 times the outer diameter of the tubes.

[0893] The above Ag-doped titanic acid nanotubes were heat-treated at 650? C. for 3 h, i.e., the anatase TiO.sub.2 nanotubes embedded with Ag nanoparticles were obtained; the size of the embedded Ag nanoparticles was 1.5 nm 5 nm, which was distributed in anatase TiO.sub.2 nanotubes by means of embeddedness, and the outer diameter of the anatase TiO.sub.2 nanotubes was 3 nm 15 nm, and the length of the tubes was more than 5 times the outer diameter of the tubes.

[0894] The above Ag-doped titanic acid nanotubes were heat-treated at 950? C. for 2 h, i.e., the rutile TiO.sub.2 nanotubes/rods embedded with Ag nanoparticles were obtained; the size of the embedded Ag nanoparticles was 1.5 nm 5 nm, and they were distributed in rutile TiO.sub.2 nanotubes/rods by means of embeddedness, and the outer diameters of the rutile TiO.sub.2 nanotubes/rods were 4 nm?20 nm. The length of the rutile TiO.sub.2 nanotubes/rods is more than 3 times of the outer diameter of the tubes/rods.

Embodiment 13

[0895] The present embodiment provides a preparation method of Ag-doped titanate nanofilm material, Ag-doped titanic acid nanofilm material, including the following steps:

[0896] The raw materials of metal Ag, Ti and Al were weighed according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percentage), and melt to obtain an alloy melt with a composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25. The alloy melt is prepared into an initial alloy in the form of ribbons with a thickness of ?100 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compound containing solid dissolved Ag.

[0897] Under atmospheric pressure, 0.5 g of the Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon and 50 ml of NaOH aqueous solution with a concentration of 10 mol/L were placed in a closed container, and the initial alloy ribbon was not in contact with the alkaline solution at the beginning;

[0898] The temperature inside the closed container, as well as the temperature of the initial alloy ribbon and the alkaline solution is raised to 150? C., at which time the closed container is in a high-pressure state, and then the Ag.sub.1Ti.sub.24.75Al.sub.74.25 initial alloy ribbon inside the closed container is mixed with the alkaline solution at this temperature, so that a violent hydrogen generation and T-removal reaction occurs. The initial Ag.sub.1Ti.sub.24.75Al.sub.74.25 alloy ribbon was nano-fragmented by the intense hydrogen generation and Al-removal reaction under the high temperature and high pressure, and the solid flocculent product containing Ag was generated by the simultaneous shape and composition reconfiguration.

[0899] The hydrogen generation and Al-removal reaction was completed within 30 s. After 30 s, the closed vessel and the reaction system were rapidly cooled down to near room temperature in cooling water, and the pressure in the closed vessel was lowered to atmospheric pressure;

[0900] After the temperature of the reaction system was reduced to ambient temperature and pressure, the solid flocculent product was separated from the alkaline solution, cleaned, and dried at 280? C. for 10 min, i.e., the Ag-doped sodium titanate nanofilm material was obtained, with the thickness of the single film ranging from 0.25 nm to 5 nm, and the average area of the film being larger than 1000 nm.sup.2, showing the characteristics of an obvious two-dimensional material. The Ag element is mainly distributed in the sodium titanate nanofilm in the form of atoms or atomic clusters.

[0901] The solid flocculent product after separation from the alkaline solution described above was dispersed in water, and then 0.025 mol/L HCl solution was gradually added to it, so that the pH value of the mixed solution was continuously decreased, and the pH value of the mixed solution was finally controlled between 3 and 5. After 5 min, the solid-liquid separation was carried out, and the solid product was cleaned, and dried at 250? C. for 15 min, which resulted in the Ag-doped titanic acid nanofilm. and the thickness of its single film was about 0.25 nm 5 nm, and the average area of the film was larger than 1000 nm.sup.2. wherein the element Ag is mainly distributed as atoms or atomic clusters in the as-prepared titanic acid nanofilm matrix.

Comparative Example 1

[0902] Under atmospheric pressure, 1 g of anatase TiO.sub.2 powder with a particle size range of 50 nm?100 nm was added to 50 ml of aqueous NaOH solution with a concentration of 10 mol/L and a temperature of its boiling point temperature (about 119? C.) with constant stirring.

[0903] After 10 min, 450 ml of room temperature water was rapidly poured into the reaction system under stirring, and the alkali concentration in the solution was reduced to 1 mol/L, and the temperature was reduced to below 40? C.

[0904] The solid material in the solution was separated from the solution, cleaned and dried, and the XRD pattern of the as-prepared product was measured, as shown in FIG. 9.

[0905] The XRD pattern of the anatase TiO.sub.2 powder before the reaction is shown in FIG. 10, it can be seen that after the reaction for 10 min, the anatase TiO.sub.2 almost did not undergo any change. According to the width of the XRD peaks, it concluded that the size of the TiO.sub.2 particles also did not change significantly. This comparative example shows that, when the Ti source is TiO.sub.2 powder, enve on the boiling temperature of the alkaline solution in the atmospheric environment, it is very difficult to break the T.sub.1-O bond of TiO.sub.2 in a short time.

Comparative Example 2

[0906] The raw materials of metal Ag, Ti and Al were weighed according to the ratio of Ag.sub.1Ti.sub.24.75Al.sub.74.25 (atomic percentage), and the alloy melt with the composition of Ag.sub.1Ti.sub.24.75Al.sub.74.25 was obtained by melting; the alloy melt was solidified into an alloy ingot, and then crushed into the initial alloy powder with a particle size of no more than 30 ?m. The initial alloy is mainly composed of TiAl.sub.3 intermetallic compound containing solid dissolved Ag.

[0907] Under atmospheric pressure, the above initial alloy powder was reacted with 10 mol/L NaOH solution at a temperature of 35? C. for 2 h, and the as-prepared products are shown in FIGS. 11 and 12. It can be seen that under the reaction conditions, the shape of the original initial alloy powder before and after the reaction was roughly unchanged, and it was still the original crushed and angular powder particles, as shown in FIG. 12, and its microstructure did not show a large number of monolithic two-dimensional thin films, but rather, it showed a nanoporous powder particle morphology with original angular. Therefore, the reaction equilibrium of the initial alloy with the alkaline solution occurring at a lower temperature is completely different from the reaction equilibrium of the present invention occurring near the boiling point temperature of the alkaline solution, and the product morphology is also completely different.

Comparative Example 3

[0908] The raw materials of metal Ti and Al were weighed according to the ratio of Ti.sub.25Al.sub.75 (atomic percent), and the alloy melt with the composition of Ti.sub.25Al.sub.75 was obtained by melting; the alloy melt was prepared into the initial alloy in the form of ribbons with a thickness of ?30 ?m by a rapid solidification method using melt spinning with copper roller. The initial alloy is mainly consisted of TiAl.sub.3 intermetallic compound.

[0909] Under atmospheric pressure, 0.25 g of the as-prepared Ti.sub.25Al.sub.75 initial alloy ribbon was added into 50 ml of aqueous NaOH solution at a concentration of 10 mol/L and a temperature of its boiling point (?119? C.) with constant stirring. The Ti.sub.25Al.sub.75 initial alloy ribbon underwent nano-fragmentation through intense hydrogen generation and Al-removal reaction in the concentrated alkaline solution, and was simultaneously reconfigured in shape and composition to generate diffusely distributed solid flocculent products in the alkaline solution.

[0910] The hydrogen generation and Al-removal reaction was finished within 15 s. The reaction temperature was hold for 2 min to ensure the completion of the reaction, and then 450 ml of room-temperature water was rapidly poured into the reaction system at one time under stirring, and the alkali concentration in the solution was lowered to 1 mol/L within 2 s, and the temperature was lowered to below 45? C.

[0911] The solid flocculent product after the above separation from the alkaline solution was dispersed in water, and then 0.025 mol/L HCl solution was gradually added to it, so that the pH value of the mixed solution was continuously decreased, and finally the pH value of the mixed solution was controlled between 2?5. After 10 min, the titanic acid nanofilm was obtained. The as-prepared titanic acid nanofilm were solid-liquid separated from the solution and cleaned, and then heat-treated for 2 h at 475? C., the anatase TiO.sub.2 nanosheet were obtained, as shown its TEM morphology and diffraction spectrum in FIG. 13. This comparative example illustrates that the titanic acid nanofilm without doping elements can undergo an obvious phase transition at 475? C., as well as an obvious morphological change from thin film to sheet at the same time.

[0912] The technical features of the above examples may be arbitrarily combined. For conciseness, all possible combinations of the technical features of the above embodiments have not been completely described. However, as long as there is no contradiction between the combinations of these technical features, they shall be considered to be within the scope of the present disclosure.

[0913] The above examples only express several embodiments of the disclosure, and their descriptions are more specific and detailed, but they cannot be interpreted as a limitation on the scope of the present disclosure. It should be noted that for one of ordinary skill in the art, several variations and improvements may be made without deviating from the concept of the disclosure, which all fall within the scope of protection of the disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.