Titanium sesquioxide material doped with transition metal elements as well as preparation method and application of titanium sesquioxide material

Abstract

The invention discloses a transition metal element doped titanium sesquioxide material and a preparation method and application thereof, and belongs to the field of oxide material preparation. According to the invention, a low-temperature water bath method and a traditional impregnation method are combined to prepare rutile type titanium dioxide rhombic nanoparticles doped with transition metal elements, and then the transition metal element doped titanium sesquioxide material is prepared by adding calcium hydride and carrying out vacuum annealing. By continuously exploring experimental conditions, the rhombic titanium sesquioxide nanoparticles doped with different transition metal elements are successfully prepared. The method is simple, the preparation cost is low, the equipment requirement is low, and the prepared doped titanium sesquioxide particles have good morphology and certain dispersity. In a reaction for synthesizing hydrogen peroxide through electro-catalytic oxygen reduction, the nickel-doped titanium sesquioxide can obtain selectivity as high as 96.6%.

Description

Titanium trioxide material doped with transition metal elements, its preparation method and application Technical Field

[0001] This invention belongs to the field of oxide material preparation, specifically relating to a titanium trioxide material doped with transition metal elements, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In recent years, titanium trioxide (TiO2) has attracted considerable attention due to its unique physical properties and wide range of applications in energy, catalysis, biomedicine, and optoelectronics. As an important member of the titanium oxide family, titanium dioxide is a wide-bandgap semiconductor (~3.3 eV) and has been extensively studied in catalysis, where trivalent titanium is considered to play a crucial role in regulating its electronic structure. In stark contrast, titanium trioxide is a pure trivalent titanium metal oxide material with an ultra-narrow bandgap (~0.1 eV), thus exhibiting stronger light absorption and photoresponse properties. Based on this, in-depth research has revealed the enormous application potential of titanium trioxide in fields such as photothermal seawater desalination, cancer treatment, and mid-infrared photoelectric detection.

[0004] With the increasing global energy shortage and severe environmental problems, fuel cells, which generate electricity efficiently using clean and renewable fuels, have attracted growing attention in recent years. Fuel cells typically involve oxidizing fuel (such as hydrogen) at the anode, releasing electrons that are transferred to the cathode via an external circuit, reducing oxygen at the cathode. This process effectively converts chemical energy into electrical energy, which can power electronic devices, homes, or vehicles. This necessitates that the oxygen reduction reaction (OR) catalytic process proceed at a high rate, with high selectivity and high energy efficiency. Despite decades of research, a fast, stable, inexpensive, and highly efficient OR electrocatalyst has yet to be discovered. Therefore, the OR remains one of the greatest challenges in chemical energy research. Currently, research on titanium trioxide nanomaterials in the field of electrocatalytic OR is attracting increasing attention. In-depth study of the mechanism and catalyst properties of electrocatalytic OR holds promise for optimizing catalytic activity and stability, promoting its application and development in various fields. This will make a significant contribution to sustainable development and human well-being.

[0005] Generally, doping and surface modification are the most common methods to improve material properties, but most known methods still produce pure titanium trioxide nanomaterial systems. Existing technologies only disclose one method for preparing doped titanium trioxide acid-resistant photocatalyst supports, but it suffers from drawbacks such as high synthesis temperature, inhomogeneous material morphology and size, and limited dopant element abundance. Therefore, finding a simple, low-cost, and safe method to prepare transition metal-doped titanium trioxide nanomaterials is of profound significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a titanium trioxide material doped with transition metal elements, its preparation method, and its applications. This invention offers a novel approach to preparing this material, combining a low-temperature water bath method with a traditional impregnation method, followed by vacuum annealing. Through continuous exploration of experimental conditions, rhombic titanium trioxide nanoparticles doped with different transition metal elements were successfully prepared.

[0007] It should be noted that in this invention, titanium dioxide without transition metal doping and titanium dioxide with transition metal doping were prepared respectively, and the crystal form of titanium dioxide in both cases was rutile phase. This invention further prepared titanium trioxide without transition metal doping and titanium trioxide with transition metal doping respectively, and the crystal form of titanium trioxide in both cases was α phase.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a titanium dioxide material doped with transition metal elements, wherein the titanium dioxide material doped with transition metal elements is obtained by reducing rutile titanium dioxide material doped with transition metal elements with calcium hydride.

[0009] Titanium trioxide consists of rhombic nanoparticles with a particle size of approximately 50-100 nm.

[0010] In one or more embodiments, the doped transition metal element is selected from cobalt (Co). 2+ ), nickel (Ni 2+ ), copper (Cu) 2+ ) and manganese (Mn 2+ At least one of the following.

[0011] The transition metal element is doped by replacing some titanium atom sites in the titanium trioxide lattice. The doping amount of the transition metal element is 0.1% to 0.6%, preferably 0.3% to 0.5% by mass.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned titanium dioxide material doped with transition metal elements, comprising the following steps: S1, preparing titanium dioxide nanomaterials by a low-temperature water bath method; S2, immersing the titanium dioxide nanomaterials in a metal salt solution to prepare titanium dioxide nanomaterials doped with transition metal elements; S3, mixing the titanium dioxide nanomaterials doped with transition metal elements and calcium hydride, and annealing them under vacuum to obtain the final product.

[0013] In one or more embodiments, the titanium dioxide is in the rutile crystal form.

[0014] In one or more embodiments, step S1 specifically includes: adding a titanium source to a stirred nitric acid aqueous solution under low temperature water bath conditions of 40~50℃, continuing to stir, and the solid obtained after standing and centrifugation is rutile titanium dioxide nanomaterial.

[0015] In this step of the invention, nitric acid must be used to adjust the pH value; no other acid can replace it.

[0016] Factors affecting the crystal form include the concentration of nitric acid, the water bath temperature, and the titration rate. The nitric acid concentration directly affects the crystal form of the formed titanium dioxide. If the concentration is below 1 mol / L, the final product will contain anatase titanium dioxide impurities. Therefore, in this invention, to obtain pure rutile titanium dioxide material, the nitric acid concentration must be greater than 1 mol / L. The water bath temperature and titration rate affect the yield and crystallinity of the final product. If the water bath temperature is below 40°C or above 50°C, or the titration rate of tetrabutyl titanate is too slow / too fast, both will lead to a decrease in titanium dioxide yield and a deterioration in crystallinity.

[0017] Furthermore, in step S1, the titanium source includes tetrabutyl titanate, 99% pure.

[0018] Furthermore, in step S1, the concentration of the nitric acid aqueous solution is 1~6 mol / L, specifically 1 mol / L, 2 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 6 mol / L, preferably 3~5 mol / L, more preferably 3.5~4.5 mol / L.

[0019] Furthermore, in step S1, the titanium source can be added by dropping, with a dropping rate of 0.5~2 drops / s, specifically 0.5 drops / s, 1 drop / s, 1.5 drops / s, or 2 drops / s.

[0020] Furthermore, in step S1, the volume ratio of the nitric acid aqueous solution to the titanium source is (50~100):(20~40), preferably (60~70):(25~35).

[0021] Alternatively, the molar ratio of tetrabutyl titanate to water in the nitric acid aqueous solution is 1:(30~40), preferably 1:35.

[0022] Furthermore, in step S1, stirring continues for 4-8 hours. During this process, a low-temperature water bath at 40-50°C is still used, and the stirring speed can be 500-1000 rpm, preferably 500-700 rpm. More preferably, stirring continues for 4-6 hours.

[0023] Furthermore, in step S1, centrifugation is followed by drying. The conditions for centrifugation and drying are not specifically limited and can be any existing conventional methods. For example, vacuum drying can be used, drying at 50~70℃ for 8~15 hours.

[0024] In one or more embodiments, step S2 specifically includes: immersing titanium dioxide nanomaterials in a metal salt solution, stirring for several days, allowing to stand, centrifuging, and drying to obtain the final product.

[0025] Furthermore, in step S2, the salt containing a transition metal element is selected from at least one of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Cu(NO3)2·4H2O, and Mn(NO3)2.

[0026] Furthermore, in step S2, the stirring speed should be maintained above 600 rpm, such as 600~1000 rpm. Stirring should be continued for 4~10 days, preferably 4~6 days.

[0027] Furthermore, in step S2, the concentration of the metal salt solution is 1~5 mol / L, specifically 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, etc., preferably 1~2 mol / L. The solvent in the metal salt solution is water.

[0028] The volume ratio of titanium source to metal salt solution is (20~40):(40~60), preferably (25~35):(45~55).

[0029] Furthermore, in step S2, the drying temperature is 60℃~80℃ to avoid the nanoparticles failing to crystallize due to excessively low temperature or agglomerating due to excessively high drying temperature.

[0030] Furthermore, step S2 also includes annealing the dried material under vacuum conditions. The annealing temperature is 300~500℃, specifically 300℃, 320℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 480℃, or 500℃, preferably 350~450℃. The annealing time is 15~30h, specifically 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, or 30h, preferably 20~25h. Preferably, the annealing holding process should be at a temperature of 400℃ for 24h to improve the crystallinity of the final reduced sample. Compared to the unannealed crystals, the calcined crystals exhibit better crystallization and are more conducive to subsequent applications.

[0031] In one or more embodiments, in step S3, the mass ratio of titanium dioxide nanoparticles doped with transition metal elements to calcium hydride is 1:(2~7), specifically 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, preferably 1:(4~6).

[0032] In one or more embodiments, in step S3, the powder sample may be mixed by grinding for a period of not less than 2 hours (e.g., 2-5 hours) to ensure that the powder sample and calcium hydride are fully mixed and to ensure that the reduction process is fully carried out in subsequent steps.

[0033] In one or more embodiments, in step S3, the vacuum annealing temperature is 400~460℃, specifically 400℃, 410℃, 420℃, 430℃, 440℃, 445℃, 446℃, 447℃, 448℃, 449℃, 450℃, 451℃, 452℃, 453℃, 454℃, 455℃, or 460℃. The annealing time is 7~10 days, specifically 7, 8, 9, or 10 days. In the process of reducing calcium hydride, especially with materials doped with transition metal elements, excessively high temperatures or excessively long times can lead to over-reduction, generating elemental metals and TiH2; excessively low temperatures or excessively short times can lead to insufficient reduction, generating intermediates such as Ti3O5. The preferred temperature for vacuum annealing is 440~460℃, more preferably 445~455℃, and most preferably 450℃. The preferred annealing time is 7~8 days, and most preferably 7 days.

[0034] In one or more embodiments, step S3, after vacuum annealing, further includes washing, separation, and drying. The number of separation and washing steps should be no less than three, and the drying process should be maintained in a vacuum environment to prevent oxidation of the titanium trioxide nanoparticles.

[0035] As a preferred embodiment, the preparation method of transition metal element-doped titanium dioxide nanoparticles involves doping with Co ions. 2+ Ni 2+ Cu 2+ Mn 2+ The preparation steps are as follows: (1) Stir the nitric acid aqueous solution continuously in a water bath and heat it to a certain temperature. Then slowly add tetrabutyl titanate to it, and then stir it in a water bath for several hours at the same temperature to obtain a suspension; (2) Take out the beaker and let it stand, then separate the solid in the suspension, add a certain mass of transition metal salt solution to it, add water and seal it, and stir it magnetically at room temperature for several days; (3) Let it stand, and dry the product obtained after centrifuging the suspension, and collect the powder sample; (4) Anneal the collected powder under vacuum conditions for a certain time, and collect the powder sample; (5) Then mix the powder sample with nano calcium hydride in a certain proportion, grind it thoroughly, and anneal it under vacuum conditions at a certain temperature for several days; (6) Take out the sample and wash it several times with a washing solvent (such as ammonium chloride methanol solution), and finally separate the product and dry it to obtain transition metal element doped titanium dioxide nanoparticles.

[0036] Thirdly, the present invention provides the application of the above-mentioned titanium trioxide material doped with transition metal elements or the titanium trioxide material doped with transition metal elements prepared by the above-mentioned preparation method in electrocatalysis. The electrocatalysis includes electrocatalytic oxygen reduction.

[0037] Fourthly, the present invention provides a method for electrocatalytic oxygen reduction to synthesize hydrogen peroxide, comprising the following steps: using the above-mentioned titanium trioxide material doped with transition metal elements as a catalyst for electrocatalytic oxygen reduction to synthesize hydrogen peroxide reaction.

[0038] Specifically, the catalyst was loaded onto a glassy carbon electrode, the electrolyte was a potassium hydroxide solution saturated with oxygen (e.g., 0.1 M), and a voltage range of 0–1.1 V (relative to a reversible hydrogen electrode) was applied. The selectivity for hydrogen peroxide was detected using a rotating disk electrode system. A selectivity as high as 96.6% was achieved in nickel-doped titanium trioxide.

[0039] One or more of the above technical solutions have the following advantages or beneficial effects: (1) The present invention uses a low temperature water bath impregnation method to prepare transition metal element doped rutile titanium dioxide rhombic nanoparticles, and then prepares titanium dioxide nanoparticles by adding calcium hydride vacuum annealing. This method is simple, has low preparation cost and low equipment requirements. The prepared doped titanium dioxide particles have good morphology and certain dispersibility.

[0040] (2) The pure titanium trioxide nanoparticles doped with different transition metal elements prepared in this invention have certain electrocatalytic oxygen reduction performance and excellent hydrogen peroxide selectivity and Faraday efficiency. In particular, the performance of nickel-doped titanium trioxide samples is better than that of titanium trioxide samples doped with other transition metal elements, and the doped titanium trioxide samples are better than titanium dioxide samples doped with the same element.

[0041] (3) Although different preparation methods (such as hydrothermal method, gel method, etc.) can all produce titanium dioxide materials, the resulting crystal form is not necessarily pure rutile; it may be anatase or a mixed crystal form. Furthermore, experimental verification shows that only rutile titanium dioxide materials can be reduced with calcium hydride to obtain titanium trioxide. Under the same conditions, anatase titanium dioxide materials cannot be reduced with calcium hydride to obtain titanium trioxide. Therefore, in this invention, transition metal element-doped rutile titanium dioxide rhombic nanoparticles can be prepared by the low-temperature water bath impregnation method in the examples, and then transition metal element-doped titanium trioxide materials can be obtained by reducing them with calcium hydride under vacuum conditions. Attached Figure Description

[0042] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0043] Figure 1 shows the XRD images of anatase titanium dioxide nanomaterials before and after reduction; Figure 2 shows the XRD images of rutile titanium dioxide nanomaterials without transition metal elements and reduced titanium dioxide nanomaterials prepared in Example 1 of this invention; Figure 3 shows the scanning electron microscope (SEM) images of rutile titanium dioxide nanomaterials without transition metal elements and reduced titanium dioxide nanomaterials prepared in Example 1 of this invention; Figure 4 shows photographs of rutile titanium dioxide nanomaterials without transition metal elements and reduced titanium dioxide nanomaterials prepared in Example 1 of this invention; Figure 5 shows a comparison between the XRD images of titanium dioxide without transition metal elements prepared in Example 1, titanium dioxide without transition metal elements prepared in Example 2, rutile titanium dioxide nanomaterials doped with Co, Ni, and Cu respectively, and reduced titanium dioxide nanomaterials and standard cards; Figure 6 shows the titanium dioxide without transition metal elements prepared in Example 1, titanium dioxide without transition metal elements prepared in Example 3, and titanium dioxide nanomaterials doped with Co, Ni, and Cu respectively. Comparison of XRD images of rutile titanium dioxide nanomaterials with u and Mn elements and reduced titanium dioxide nanomaterials with standard cards; Figure 7 shows scanning electron microscope (SEM) images of titanium dioxide without transition metal elements prepared in Example 1 of the present invention and reduced titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn elements respectively prepared in Example 3; Figure 8 shows photographs of titanium dioxide without transition metal elements prepared in Example 1 of the present invention, titanium dioxide without transition metal elements prepared in Example 3, rutile titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn elements respectively, and reduced titanium dioxide nanomaterials; Figure 9 shows the electrocatalytic performance of titanium dioxide without transition metal elements prepared in Example 3 of the present invention and rutile titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn elements respectively; Figure 10 shows the electrocatalytic performance of titanium dioxide without transition metal elements prepared in Example 1 of the present invention and reduced titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn elements respectively prepared in Example 3. Detailed Implementation

[0044] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0045] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0046] Example 1: 63.18 mL of a 4 mol / L nitric acid aqueous solution was weighed into a beaker and heated to 45°C with continuous stirring in a water bath. 30 mL of tetrabutyl titanate was added dropwise to the solution at a rate of 1 drop / s, and the mixture was kept under magnetic stirring in a water bath at 45°C and 600 rpm for 5 hours. The beaker was removed and allowed to stand. After centrifugation, a pure white solid was obtained and dried in a 60°C oven for 10 hours, then the white powder was collected. The obtained white powder was then mixed with calcium hydride at a mass ratio of 1:5 in a mortar and ground thoroughly for 2 hours. The mixture was then compressed into tablets, placed in quartz tubes, and annealed under vacuum at 400°C for 7 days. The black powder sample was washed three times with ammonium chloride methanol solution, and finally the product was separated and vacuum dried to obtain black titanium trioxide nanoparticles.

[0047] Figure 2 shows the XRD patterns of the rutile phase titanium dioxide nanomaterials without transition metal elements and the reduced titanium trioxide nanomaterials prepared in Example 1, indicating that the prepared nanomaterials are rutile titanium dioxide and titanium trioxide, respectively.

[0048] Figure 3 shows scanning electron microscope (SEM) images of the rutile phase titanium dioxide nanomaterials without transition metal elements and the reduced titanium trioxide nanomaterials prepared in Example 1. It can be seen that both exhibit rhomboid nanoparticles with a size of about 50-80 nm, but the rutile phase titanium dioxide has better dispersibility than the black titanium trioxide.

[0049] Figure 4 shows photographs of rutile phase titanium dioxide nanomaterials without transition metal elements prepared in Example 1 and reduced titanium dioxide nanomaterials.

[0050] Example 2: A method for preparing titanium dioxide nanomaterials doped with transition metal elements, comprising the following steps: Weigh 63.18 mL of a 4 mol / L nitric acid aqueous solution into a beaker, place it in a water bath and heat it to 45°C with continuous stirring. Add 30 mL of tetrabutyl titanate to the solution at a rate of 1 drop / s, and then maintain the mixture at 45°C and 600 rpm with magnetic stirring in a water bath for 5 hours. Remove the beaker and let it stand, separating the white solid. Add 50 mL of a 1.5 mol / L transition metal salt solution (the transition metal salt solution is Co(NO3)2·6H2O, Ni(NO3)2·6H2O, or Cu(NO3)2·4H2O) to the solid. Seal the beaker with plastic wrap and perform magnetic stirring at room temperature for 5 days. After stirring, remove the beaker and let it stand. Centrifuge the suspension and dry the resulting product in a 60°C oven for 10 hours, then collect the powder. The resulting white powder was then mixed with calcium hydride at a mass ratio of 1:5 in a mortar and ground thoroughly for 2 hours. After pressing into tablets, the tablets were placed in quartz tubes and annealed at 450°C for 7 days under vacuum. The black powder sample was then removed and washed three times with ammonium chloride methanol solution. Finally, the product was separated and vacuum dried to obtain black titanium trioxide nanoparticles doped with transition metal elements.

[0051] Figure 5 shows a comparison of the XRD images of titanium dioxide without transition metal elements prepared in Example 1, titanium dioxide without transition metal elements prepared in Example 2, pure rutile phase titanium dioxide nanomaterials doped with Co, Ni, and Cu elements, and reduced titanium dioxide nanomaterials with standard cards.

[0052] Example 3: Weigh 63.18 mL of a 4 mol / L nitric acid aqueous solution into a beaker, place it in a water bath and heat it to 45°C with continuous stirring. Add 30 mL of tetrabutyl titanate dropwise to the solution at a rate of 1 drop / s, and then maintain the mixture at 45°C and 600 rpm with magnetic stirring in a water bath for 5 hours. Remove the beaker and let it stand, separating the white solid. Add 50 mL of a 1.5 mol / L transition metal salt solution (the transition metal salt solution is Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Cu(NO3)2·4H2O, or Mn(NO3)2) to the solid. Seal the beaker with plastic wrap and stir magnetically at room temperature for 5 days. After stirring, remove the beaker and let it stand. Centrifuge the suspension and dry the resulting product in a 60°C oven for 10 hours. Collect the powder and anneal the collected powder at 400°C under vacuum for 24 hours. The resulting white powder was then mixed with calcium hydride at a mass ratio of 1:5 in a mortar and ground thoroughly for 2 hours. After pressing into tablets, the tablets were placed in quartz tubes and annealed at 450°C for 7 days under vacuum. The black powder sample was then removed and washed three times with ammonium chloride methanol solution. Finally, the product was separated and vacuum dried to obtain black titanium trioxide nanoparticles doped with transition metal elements.

[0053] Figure 6 shows a comparison of the XRD images of titanium dioxide without transition metal elements prepared in Example 1, titanium dioxide without transition metal elements prepared in Example 3, rutile phase titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn, and reduced titanium dioxide nanomaterials with standard cards.

[0054] Figure 7 shows scanning electron microscope (SEM) images of titanium trioxide nanomaterials prepared in Example 1 without transition metal doping and titanium trioxide nanomaterials prepared in Example 3 after reduction with Co, Ni, Cu and Mn doping.

[0055] Figure 8 shows photographs of titanium dioxide without transition metal elements prepared in Example 1, titanium dioxide without transition metal elements prepared in Example 3, rutile phase titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn, and reduced titanium dioxide nanomaterials.

[0056] The difference between Comparative Example 1 and Example 1 is that, in the calcium hydride reduction, commercial anatase nano-titanium dioxide was used instead of the rutile titanium dioxide synthesized in Example 1. The experiment showed that, as shown in Figure 1, under the same reduction conditions, the product was still mainly titanium dioxide, and titanium trioxide could not be obtained. Therefore, in the process of calcium hydride reduction, only rutile titanium dioxide can be reduced to titanium trioxide.

[0057] The difference between Comparative Example 2 and Example 1 is that in the process of preparing rutile phase titanium dioxide in a low-temperature water bath, the concentration of nitric acid aqueous solution is less than 1 mol / L, and the final titanium dioxide obtained will have anatase impurity phase.

[0058] Electrocatalytic reduction test: Specifically, the catalyst was supported on a glassy carbon electrode (the catalyst dosage in electrocatalysis was 0.2~0.8 mg / cm³). 2 The mass of the catalyst and the area of ​​the working electrode in the electrocatalytic test are shown in the figure. The electrolyte is a 0.1M potassium hydroxide solution saturated with oxygen. The applied voltage range is 0~1.1 V (relative to the reversible hydrogen electrode). The selectivity of hydrogen peroxide is detected using a rotating disk electrode system. A selectivity as high as 96.6% can be obtained in nickel-doped titanium trioxide.

[0059] Figures 9 and 10 show the electrocatalytic performance of titanium dioxide nanomaterials prepared in Example 1 without transition metal doping, titanium dioxide nanomaterials prepared in Example 3 without transition metal doping, rutile phase titanium dioxide nanomaterials doped with Co, Ni, Cu, and Mn, and reduced titanium dioxide nanomaterials.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A titanium trioxide material doped with transition metal elements, characterized in that, The titanium dioxide material doped with transition metal elements is obtained by reducing rutile titanium dioxide material doped with transition metal elements with calcium hydride. Titanium trioxide doped with transition metal elements is a rhombic nanoparticle with an α-phase crystal structure; the doping amount of transition metal elements is 0.1~0.6% by mass.

2. The titanium trioxide material according to claim 1, characterized in that, The doping amount of the transition metal element is 0.3 to 0.5% by mass; preferably, the doped transition metal element is selected from at least one of cobalt, nickel, copper and manganese; preferably, the nanoparticle size is 50 to 100 nm.

3. A method for preparing titanium trioxide material doped with transition metal elements as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Titanium dioxide nanomaterials are prepared by low-temperature water bath method; S2. The titanium dioxide nanomaterials are immersed in metal salt solution to prepare titanium dioxide nanomaterials doped with transition metal elements; S3. The titanium dioxide nanomaterials doped with transition metal elements are mixed with calcium hydride and vacuum annealed to obtain titanium trioxide nanomaterials doped with transition metal elements.

4. The preparation method according to claim 3, characterized in that, The titanium dioxide has a rutile crystal form.

5. The preparation method according to claim 3, characterized in that, In step S1, the specific preparation method includes: adding a titanium source to a stirred nitric acid aqueous solution under low temperature water bath conditions of 40~50℃, continuing to stir, and the solid obtained after standing and centrifugation is titanium dioxide nanomaterial.

6. The preparation method according to claim 5, characterized in that, In step S1, the titanium source includes tetrabutyl titanate; preferably, in step S1, the concentration of the nitric acid aqueous solution is 1~6 mol / L; preferably, in step S1, the volume ratio of the nitric acid aqueous solution to the titanium source is (50~100):(20~40), more preferably (60~70):(25~35); preferably, in step S1, stirring is continued for 4~8 hours.

7. The preparation method according to claim 3, characterized in that, In step S2, the preparation method specifically includes: immersing titanium dioxide nanomaterials in a metal salt solution, stirring for several days, allowing to stand, centrifuging, and drying to obtain the final product; preferably, in step S2, the salt containing transition metal elements is selected from at least one of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Cu(NO3)2·4H2O, and Mn(NO3)2; preferably, in step S2, the stirring speed should be maintained above 600 rpm, and stirring should be continued for 4 to 10 days, preferably 4 to 6 days; preferably, in step S2... In step S2, the concentration of the metal salt solution is 1~5 mol / L, preferably 1~2 mol / L; preferably, the volume ratio of the titanium source to the metal salt solution is (20~40):(40~60), preferably (25~35):(45~55); preferably, in step S2, the drying temperature is 60℃~80℃; preferably, in step S2, the dried material is further annealed under vacuum conditions; the annealing temperature is 300~500℃, preferably 350~450℃; the annealing time is 15~30h, preferably 20~25h.

8. The preparation method according to claim 3, characterized in that, In step S3, the mass ratio of titanium dioxide nanoparticles doped with transition metal elements to calcium hydride is 1:(2~7), preferably 1:(4~6); preferably, in step S3, the mixing can be carried out by grinding, and the grinding time should be no less than 2 hours; preferably, in step S3, the vacuum annealing temperature is 400~460℃, preferably 440~460℃; the annealing time is 7~10 days, preferably 7~8 days.

9. The application of a titanium trioxide material doped with transition metal elements as described in claim 1 or 2, or a titanium trioxide material doped with transition metal elements prepared by any one of claims 3 to 8, in electrocatalysis.

10. A method for electrocatalytic oxygen reduction to synthesize hydrogen peroxide, characterized in that, The method includes the following steps: using the titanium trioxide material doped with transition metal elements as described in claim 1 or 2, or the titanium trioxide material doped with transition metal elements prepared by the preparation method described in any one of claims 3 to 8, as a catalyst for electrocatalytic oxygen reduction.

Images