Titanium vacancy titania and a method of making the same

Abstract

The application belongs to the field of nanometer functional material preparation, and particularly relates to a titanium vacancy titanium dioxide and a preparation method thereof. The titanium vacancy titanium dioxide comprises the following steps: 1) mixing a titanium source with deionized water to configure a titanium ion solution, and then mixing the titanium ion solution with a metal salt and urea to obtain a precursor solution; 2) adding the precursor solution obtained in step 1) into a reaction kettle to perform a hydrothermal reaction, so as to obtain a metal ion composite titanium dioxide; 3) mixing the metal ion composite titanium dioxide obtained in step 2) with an extractant and a solvent, adding into the solvent, and then putting into a reaction kettle to react, so as to obtain a titanium vacancy titanium dioxide / metal compound composite material; and 4) adding the titanium dioxide / metal sulfide composite material obtained in step 3) into a directional dissolution solution, and then performing a reaction to obtain the titanium vacancy titanium dioxide. By accurately controlling the molar ratio of the doped metal ion and the titanium ion in step 1), the content of the final titanium vacancy can be accurately controlled.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation, and particularly relates to a titanium vacancy titanium dioxide and its preparation method. Background Technology

[0002] Titanium dioxide (TiO2), as an important wide-bandgap semiconductor material, has shown great application potential in environmental remediation, energy conversion, and biomedicine due to its excellent photocatalytic activity, chemical stability, and non-toxicity. However, pure titanium dioxide typically suffers from high photogenerated carrier recombination rates and poor visible light response, limiting further performance improvements. Research shows that introducing defects, such as oxygen vacancies or titanium vacancies, into the titanium dioxide crystal structure can effectively modulate its electronic structure, improve carrier separation efficiency, and enhance visible light absorption, thereby significantly improving its photocatalytic and photoelectric properties. In particular, titanium vacancies can act as trapping centers, promoting charge separation and potentially introducing new energy levels, thus broadening the spectral response range.

[0003] However, the formation energy of titanium vacancies in titanium dioxide is relatively high. Traditional vacancy introduction techniques (such as high-temperature annealing and reducing atmosphere treatment) can only stably introduce oxygen vacancies, making it difficult to obtain titanium vacancies. Existing preparation methods mainly obtain oxygen-vacancy titanium dioxide by creating an oxygen-rich environment. For example, Wang et al. used glycerol in their synthesis, which reacted with the titanium precursor to form layered titanium glycerol ester (TiGly). During subsequent calcination in air, the organic groups between the TiGly layers were removed, forming a local oxygen-rich environment that drove the formation and stabilization of titanium vacancies (Journal of the American Chemical Society, 2015, 137(8): 2975-2983). Similarly, Yang Xiaoyu et al. (CN 202410745091.5) and Shen Yi et al. (ZL 202210423640.8) also synthesized titanium vacancy titanium dioxide using glycerol.

[0004] While the above methods can prepare titanium dioxide with titanium vacancies, the main principle involves the formation of layered TiGly layers from a titanium source and glycerol. Heating in air removes the organic groups between the TiGly layers, creating a locally oxygen-rich environment that generates titanium vacancies. However, the formation of this locally oxygen-rich environment is uncontrollable, making it difficult to precisely control the titanium vacancy content and limiting the further development of titanium dioxide with titanium vacancies in high-performance applications. Therefore, developing a novel preparation method that can efficiently, stably, and precisely control the titanium vacancy content in titanium dioxide is a crucial problem urgently needing to be solved in the current titanium dioxide research field. Summary of the Invention

[0005] The present invention aims to provide a method for preparing titanium dioxide with titanium vacancies, thereby solving the problems of difficulty in preparing titanium vacancies and difficulty in accurately controlling their content in titanium dioxide.

[0006] Specifically, the present invention provides a method for preparing titanium dioxide with titanium vacancies, comprising the following steps: 1) Mix the titanium source with deionized water to prepare a titanium ion solution with a concentration of 0.1-1 mol / L, and then mix the titanium ion solution with metal salt and urea to obtain a precursor solution; 2) Add the precursor solution obtained in step 1) into the reactor and carry out a hydrothermal reaction at 100~180℃ for 8~12h to obtain metal ion composite titanium dioxide; 3) The metal ion composite titanium dioxide obtained in step 2) is mixed with the extractant and solvent. The mixture is then placed in a reaction vessel and reacted at 180-300℃ for 6-48 hours to obtain a titanium vacancy titanium dioxide / metal compound composite material. Because the extractant provides a sulfur-containing reaction environment, and the solubility product of these metal elements' sulfides is less than that of their oxides, the metal elements migrate out of the titanium dioxide lattice and form metal sulfide compounds with the sulfur elements in the extractant. This leaves titanium vacancies in the titanium dioxide lattice, resulting in a titanium vacancy titanium dioxide / metal compound. Therefore, the role of the extractant is to extract metal ions from the metal composite titanium dioxide to form metal compounds, leaving titanium vacancies in the original titanium dioxide structure.

[0007] 4) Add the titanium dioxide / metal sulfide composite material from step 3) to the directional dissolution solution and react at 20–100°C for 1–12 hours to obtain titanium dioxide with titanium vacancies. The role of the directional dissolution solution is to dissolve the metal compound in the titanium dioxide / metal compound, leaving titanium dioxide with titanium vacancies.

[0008] Furthermore, the titanium source is an organic titanium source and / or an inorganic titanium source; it can be one or more of titanium oxysulfate, titanium tetrachloride, or tetrabutyl titanate.

[0009] Furthermore, the metal salt in step 1) is selected from one or more of cadmium salts, tin salts, bismuth salts, iron salts, manganese salts, and zinc salts, preferably one or more of cadmium chloride, cadmium nitrate, tin chloride, bismuth chloride, ferric chloride, ferric nitrate, manganese chloride, manganese nitrate, zinc chloride, or zinc nitrate.

[0010] Furthermore, in step 1), the molar ratio of titanium ions in the titanium ion solution to metal ions in the metal salt and urea is 100:(0.1-30):200.

[0011] Furthermore, the extractant in step 3) is organic sulfur or negatively valent inorganic sulfur; furthermore, the extractant is one or more of sodium sulfide, thioacetamide, thiourea, carbon disulfide or sodium hydrosulfide.

[0012] Furthermore, the solvent in step 3) is one or more of deionized water, ethanol, isopropanol, ethylene glycol, and glycerol.

[0013] Furthermore, in step 3), the mass ratio of the metal composite titanium dioxide to the extractant is 100:(10-30), and the mass ratio of the metal composite titanium dioxide to the solvent is (1-10):100.

[0014] Furthermore, the directional dissolving solution in step 4) is one or more of hydrochloric acid, nitric acid, sulfuric acid or acetic acid, preferably hydrochloric acid or nitric acid with a concentration of 0.05 to 3 mol / L.

[0015] A titanium dioxide with titanium vacancies is prepared according to the above preparation method, wherein the molar ratio of titanium vacancies to titanium is 0.1-30%, and the particle size is 5-15 nm.

[0016] Through the above technical solution, the present invention utilizes the following principle to prepare titanium dioxide with titanium vacancies: First, a specific type of metal salt is introduced into the synthesis environment of titanium dioxide. The metal ions in the metal salt will replace some of the titanium ions and enter the titanium dioxide lattice to form metal composite titanium dioxide. The ratio of metal ions and titanium ions in the titanium dioxide lattice can be precisely controlled by adjusting the amount of metal salt added.

[0017] Secondly, the metal composite titanium dioxide is subjected to a high-temperature hydrothermal reaction with an extractant (sulfur-containing compound). Utilizing the concentration product difference between metal sulfides, metal oxides, and metal hydroxides, metal ions are extracted from the titanium dioxide lattice while preserving the titanium dioxide lattice structure. The extracted metal ions then form complex metal compounds with sulfur, oxygen, hydrogen, and other elements, thus forming a titanium vacancy titanium dioxide / metal compound composite material.

[0018] Finally, by utilizing the difference in solubility between the metal compound and titanium dioxide in the solution, the metal compound is dissolved and removed, leaving only titanium dioxide with titanium vacancies. After centrifugation, washing, and drying, titanium dioxide with titanium vacancies is obtained. The content of titanium vacancies can be controlled by the ratio of metal ions to titanium ions.

[0019] The beneficial effects of this invention are at least as follows: By precisely controlling the molar ratio of the doped metal ions to titanium ions in step 1), the final titanium vacancy content can be precisely controlled. This allows for the customization of titanium dioxide materials with specific vacancy concentrations according to actual application requirements, providing new possibilities for the development of high-performance functional materials. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 These are XRD patterns of titanium dioxide with titanium vacancies prepared in Examples 1 to 5 of this invention; Figure 2 This is a diagram showing the ratio of titanium vacancies to titanium atoms in titanium dioxide prepared according to Examples 1 to 5 of this invention; Figure 3 These are performance graphs of titanium dioxide with vacancy prepared in Examples 1 to 5 of this invention and its ability to degrade benzene with P25. Figure 4 This is a transmission electron microscope image of the titanium vacancy titanium dioxide prepared in Example 1 of the present invention; Figure 5 This is a transmission electron microscope image of the titanium vacancy titanium dioxide prepared in Example 2 of the present invention; Figure 6 This is a transmission electron microscope image of the titanium vacancy titanium dioxide prepared in Example 3 of the present invention; Figure 7 This is a transmission electron microscope image of the titanium vacancy titanium dioxide prepared in Example 4 of the present invention; Figure 8 This is a transmission electron microscope (TEM) image of the titanium vacancy titanium dioxide prepared in Example 5 of the present invention. Detailed Implementation

[0022] The following is a reference to the appendix. Figures 1 to 5 Alternatively, specific embodiments may be used to further illustrate the present invention in detail.

[0023] Various modifications and embodiments can be applied to this invention, with specific examples shown in the drawings and detailed descriptions. However, this is not intended to limit the invention to a particular embodiment, but rather to encompass all variations, equivalents, and substitutions included within the spirit and scope of the invention. In describing this invention, detailed descriptions of relevant prior art are omitted if they are deemed to obscure the main points of the invention.

[0024] The terminology used in this application is for illustrative purposes only and is not intended to limit the invention. Singular expressions are included unless explicitly defined, and plural expressions are also included. In this application, terms such as "comprising" or "having" should be understood to specify the presence of features, numbers, steps, actions, constituent elements, components, or combinations thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, actions, constituent elements, components, or combinations thereof.

[0025] The terms "first," "second," etc., can be used in the description of various constituent elements, but the constituent elements are not limited by the terms. The terms are used only for the purpose of distinguishing one constituent element from another.

[0026] Based on the entirety of the specification, when it is mentioned that one component is located "on" another component, it can be understood that the one component is in direct contact with the other component, or that there may be other components disposed in between. Conversely, when it is mentioned that one component is located "directly" on another component, it can be understood that there are no other components disposed in between.

[0027] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product manual. Instruments and other equipment whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are all obtainable from publicly available commercial sources.

[0028] Example 1 Titanium tetrachloride was prepared into a 1 mol / L titanium ion solution with deionized water. Then, cadmium chloride and urea were added to the solution in a molar ratio of titanium ions: cadmium ions: urea of ​​100: 0.1: 200. After mixing, the solution was reacted in a reactor at 100°C for 12 h to obtain cadmium composite titanium dioxide. Cadmium-containing composite titanium dioxide and thiourea were mixed at a mass ratio of 100:10 and added to deionized water. The mass ratio of cadmium-containing composite titanium dioxide to deionized water was 1:100. After stirring evenly, the mixture was placed in a reaction vessel and reacted at 180°C for 6 hours to obtain titanium vacancy titanium dioxide / cadmium compound composite material. Titanium vacancy titanium dioxide / cadmium compound composite material was added to 0.05 mol / L dilute hydrochloric acid and reacted at 100℃ for 12 h. After centrifugation, washing and drying with deionized water, titanium vacancy titanium dioxide was obtained.

[0029] Example 2

[0030] Titanium oxysulfate and deionized water were used to prepare a 1 mol / L titanium ion solution. Then, tin chloride and urea were added to the solution in a molar ratio of titanium ions: tin ions: urea of ​​100:30:200. After mixing, the solution was reacted in a reactor at 180°C for 12 h to obtain tin composite titanium dioxide. Tin-composite titanium dioxide and thioacetamide were mixed at a mass ratio of 100:30 and added to deionized water. The mass ratio of cadmium-composite titanium dioxide to water was 10:100. After stirring evenly, the mixture was placed in a reaction vessel and reacted at 300℃ for 48 hours to obtain titanium vacancy titanium dioxide / tin compound composite material. Titanium vacancy titanium dioxide / tin compound composite material was added to 3 mol / L dilute nitric acid and reacted at 20 °C for 1 h. After centrifugation, washing and drying with deionized water, titanium vacancy titanium dioxide was obtained.

[0031] Example 3

[0032] Tetrabutyl titanate and deionized water were used to prepare a 1 mol / L titanium ion solution. Then, manganese chloride and urea were added to the solution in a molar ratio of titanium ion: manganese ion: urea of ​​100:15:200. After mixing, the solution was reacted in a reactor at 150°C for 10 h to obtain manganese composite titanium dioxide. Manganese composite titanium dioxide and sodium sulfide were mixed at a mass ratio of 100:10 and added to deionized water. The mass ratio of manganese composite titanium dioxide to water was 5:100. After stirring evenly, the mixture was placed in a reaction vessel and reacted at 220℃ for 30 hours to obtain titanium dioxide / manganese compound composite material with titanium vacancies. Titanium vacancy titanium dioxide / cadmium compound composite material was added to 0.05 mol / L dilute hydrochloric acid and reacted at 100℃ for 12 h. After centrifugation, washing and drying with deionized water, titanium vacancy titanium dioxide was obtained.

[0033] Example 4 Titanium tetrachloride was prepared into a 1 mol / L titanium ion solution with deionized water. Then, manganese chloride, zinc nitrate and urea were added to the solution in a molar ratio of titanium ion:(manganese ion + zinc ion):urea of ​​100:(10+5):200. After mixing, the solution was reacted in a reactor at 140℃ for 8 h to obtain manganese-zinc composite titanium dioxide. Manganese-zinc composite titanium dioxide and sodium sulfide were mixed at a mass ratio of 100:20 and added to a mixed solution of deionized water and ethanol. The mass ratio of cadmium composite titanium dioxide to the mixed solution was 5:100. After stirring evenly, the mixture was placed in a reaction vessel and reacted at 250℃ for 24 hours to obtain titanium vacancy titanium dioxide / manganese-zinc compound composite material. Titanium vacancy titanium dioxide / manganese zinc compound composite material was added to 1 mol / L dilute sulfuric acid and reacted at 150 °C for 4 h. After centrifugation, washing and drying with deionized water, titanium vacancy titanium dioxide was obtained.

[0034] Example 5 Tetrabutyl titanate and deionized water were used to prepare a 1 mol / L titanium ion solution. Then, bismuth chloride and urea were added to the solution in a molar ratio of titanium ion: bismuth ion: urea of ​​100:18:200. After mixing, the solution was reacted in a reactor at 120°C for 12 h to obtain bismuth composite titanium dioxide. Bismuth composite titanium dioxide and carbon disulfide were mixed at a mass ratio of 100:15 and added to ethylene glycol. The mass ratio of cadmium composite titanium dioxide to solvent was 4:100. After stirring evenly, the mixture was placed in a reaction vessel and reacted at 200℃ for 32 hours to obtain titanium vacancy titanium dioxide / bismuth compound composite material. Titanium vacancy titanium dioxide / bismuth compound composite material was added to 1.2 mol / L dilute hydrochloric acid and reacted at 40 °C for 7 h. After centrifugation, washing and drying with deionized water, titanium vacancy titanium dioxide was obtained.

[0035] The titanium dioxide with titanium vacancies prepared according to the methods described in Examples 1-5 were tested respectively, and the results are as follows: 1. The titanium vacancy titanium dioxide prepared in Examples 1 to 55 of this invention was subjected to XRD analysis using an XRD instrument. Comparison of the results with the XRD patterns of anatase phase titanium dioxide revealed that the peak positions were identical to the standard peaks of anatase phase titanium dioxide. Therefore, it can be determined that the prepared titanium vacancy titanium dioxide is anatase phase titanium dioxide. Figure 1 As shown. The XRD test was performed by compacting the powder in a mold and then testing it with a Bruker XRD analyzer at a scanning speed of 8° / min and a test range of 20° to 80°.

[0036] 2. By measuring the titanium content in the material and comparing it with the theoretical value in TiO2, the content of titanium vacancies can be obtained. For example... Figure 2 As shown, Figure 2 This refers to the ratio of titanium vacancies to titanium atoms in the titanium dioxide prepared in Examples 1 to 5 of this invention. It demonstrates that the proportion of titanium vacancies in the final titanium dioxide can be precisely controlled by adjusting the ratio of metal elements to titanium atoms in step 1. The specific testing process is as follows: Take a sample with mass m0, dissolve it by heating with a mixture of sulfuric acid and nitric acid or nitric acid and hydrofluoric acid, bring the volume of the dissolved liquid to a fixed level, and then use inductively coupled plasma mass spectrometry (ICP-MS) to test the concentration of titanium in the liquid. Finally, obtain the mass m1 of titanium in the sample by the liquid volume and the concentration of titanium. Then the mass m2 of oxygen in the sample is m2 = m0 - m1. Based on the atomic weight of titanium (47.867) and oxygen (15.9999), the theoretical mass ratio of titanium to oxygen in TiO2 is 1.4958. Therefore, if there were no titanium vacancies in the sample, the theoretical mass of titanium would be m3 = 1.4958 × m2 = 1.4958 × (m0 - m1). Thus, the mass of titanium vacancies in the sample is m3 - m1 = 1.4958m0 - 2.4958m1. The ratio of titanium vacancies to titanium is (1.4958m0 - 2.4958m1) / m1 × 100%.

[0037] 3. The titanium vacancy titanium dioxide prepared in Examples 1 to 5 of this invention and the control sample P25 were degraded into benzene under visible light. Figure 3 As can be seen above, the degradation ability of P25 is worse than that of the titanium vacancy titanium dioxide prepared in this invention, indicating that the titanium vacancy titanium dioxide prepared in this invention has good visible light photocatalytic performance. The specific test steps are as follows: For the benzene degradation test, 30 mg of powder was first added to 1 mL of anhydrous ethanol, sonicated for 5 min, and then dropped onto a 5 cm × 5 cm glass slide. After drying, it was placed in a sealed container, and benzene standard gas was introduced into it, with a final concentration of approximately 20 ppm. Then, light was applied for irradiation, and the benzene concentration in the air in the container was measured every 30 min. The photocatalytic performance of the sample was characterized based on the change in benzene concentration.

[0038] 4. The titanium dioxide with titanium vacancies prepared in Examples 1 to 5 of this invention were subjected to transmission electron microscopy (TEM). The test results are as follows: Figures 4 to 8 As shown, from Figures 4 to 8 As can be seen, the prepared sample consists of nanoparticles. The specific steps for TEM testing are as follows: 10 mg of powder is added to 5 mL of anhydrous ethanol, sonicated for 5 min, and then dropped onto a copper grid using a pipette, followed by observation using a transmission electron microscope.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing titanium dioxide with titanium vacancies, characterized in that, Includes the following steps: 1) Mix the titanium source with deionized water to prepare a titanium ion solution with a concentration of 0.1-1 mol / L, and then mix the titanium ion solution with metal salt and urea to obtain a precursor solution; 2) Add the precursor solution obtained in step 1) into the reactor and carry out a hydrothermal reaction at 100~180℃ for 8~12h to obtain metal ion composite titanium dioxide; 3) The metal ion composite titanium dioxide obtained in step 2) is mixed with the extractant and solvent, added to the solvent, and placed in a reaction vessel to react at 180~300℃ for 6~48h to obtain titanium vacancy titanium dioxide / metal compound composite material. 4) Add the titanium dioxide / metal sulfide composite material from step 3) to the directional solution and react at 20–100°C for 1–12 h to obtain titanium dioxide with titanium vacancies.

2. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, Step 1) The titanium source is an organic titanium source and / or an inorganic titanium source, preferably one or more of titanium oxysulfate, titanium tetrachloride or tetrabutyl titanate.

3. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, Step 1) The metal salt is selected from one or more of cadmium salts, tin salts, bismuth salts, iron salts, manganese salts, and zinc salts, preferably one or more of cadmium chloride, cadmium nitrate, tin chloride, bismuth chloride, ferric chloride, ferric nitrate, manganese chloride, manganese nitrate, zinc chloride, or zinc nitrate.

4. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, In step 1), the molar ratio of titanium ions in the titanium ion solution to metal ions in the metal salt and urea is 100:(0.1-30):

200.

5. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, Step 3) The extractant is organic sulfur or negatively valence inorganic sulfur.

6. The method for preparing titanium dioxide with titanium vacancies according to claim 5, characterized in that... The extractant is one or more of sodium sulfide, thioacetamide, thiourea, carbon disulfide, or sodium hydrosulfide.

7. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, Step 3) The solvent is one or more of deionized water, ethanol, isopropanol, ethylene glycol, and glycerol.

8. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, In step 3), the mass ratio of the metal composite titanium dioxide to the extractant is 100:(10-30), and the mass ratio of the metal composite titanium dioxide to the solvent is (1-10):

100.

9. The method for preparing titanium dioxide with titanium vacancies according to claim 1, characterized in that, Step 4) The directional dissolving solution is one or more of hydrochloric acid, nitric acid, sulfuric acid or acetic acid, preferably hydrochloric acid or nitric acid with a concentration of 0.05 to 3 mol / L.

10. A titanium dioxide with titanium vacancies, prepared by the method according to any one of claims 1-10, characterized in that, The molar ratio of titanium vacancies to titanium is 0.1-30%, and the particle size is 5-15 nm.

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