A TiO2 / MnO2 heterostructured nanocatalyst, its preparation method and application

Abstract

This invention discloses a TiO2 / MnO2 heterostructured nanocatalyst, its preparation method, and its applications. The nanocatalyst uses nano-TiO2 as the main component, with MnO2 grown in situ on the surface of the nano-TiO2. The TiO2 content is >95 wt.%, and the remainder is MnO2 grown in situ. The particle size of the TiO2 / MnO2 heterostructured nanocatalyst is d = 10–40 nm; the specific surface area of ​​the TiO2 / MnO2 heterostructured nanocatalyst is 20–50 cm². 3 / g. This invention utilizes a multi-step, progressively optimized synthesis strategy to chemically combine TiO2 and MnO2, fully leveraging the catalytic advantages of TiO2 and MnO2 in the field of magnesium-based hydrogen storage materials, to obtain a TiO2 / MnO2 heterostructure nanocatalyst that simultaneously handles hydrogen absorption and desorption processes.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage material catalysis technology, specifically relating to a TiO2 / MnO2 heterostructure nanocatalyst, its preparation method, and its application. Background Technology

[0002] The large-scale application of hydrogen energy is constrained by bottlenecks in hydrogen storage technology, particularly in terms of safety and efficiency. Against this backdrop, solid-state hydrogen storage technology, due to its safety, reliability, and high hydrogen storage density, is considered a key breakthrough for the development of the hydrogen energy industry. Magnesium-based solid-state hydrogen storage materials, with their high hydrogen storage capacity, wide resource distribution, and economic viability, have become the most promising research direction in the field. However, the commercial application of magnesium-based hydrogen storage materials is limited by problems such as slow hydrogen absorption and desorption kinetics and unstable thermodynamic properties. The main reason is that the formation of a passivation layer on the surface of magnesium-based hydrogen storage materials hinders the hydrogen absorption process, while the stable structure of MgH2 hinders its hydrogen desorption process. Therefore, researchers have widely adopted surface catalysis methods to optimize and modify these materials. Based on the roles of each element in magnesium-based hydrogen storage materials, the preparation of highly efficient catalysts has also become a current research focus.

[0003] TiO2 is a typical metal oxide widely used in catalysis research across various fields. However, in the field of magnesium-based hydrogen storage materials, the catalytic performance of traditional commercial TiO2 is limited by its large particle size and monolithic morphology. Although current research has optimized and regulated TiO2, TiO2 alone cannot simultaneously optimize both hydrogen absorption and desorption processes. Summary of the Invention

[0004] To overcome the problems existing in the prior art, the present invention aims to provide a TiO2 / MnO2 heterostructure nanocatalyst, its preparation method, and its application. This method uses a multi-step, progressively optimized synthesis strategy to chemically combine TiO2 and MnO2, fully leveraging the catalytic advantages of TiO2 and MnO2 in the field of magnesium-based hydrogen storage materials, and obtaining a TiO2 / MnO2 heterostructure nanocatalyst that simultaneously handles hydrogen absorption and desorption processes.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A TiO2 / MnO2 heterostructured nanocatalyst, comprising nano-TiO2 as the main body, with MnO2 grown in situ on the surface of nano-TiO2, wherein TiO2 accounts for >95wt.% and the remainder is MnO2 grown in situ;

[0007] The particle size of the TiO2 / MnO2 heterostructured nanocatalyst is d = 10–40 nm;

[0008] The specific surface area of ​​TiO2 / MnO2 heterostructured nanocatalysts is 20–50 cm². 3 / g.

[0009] TiO2 / MnO2 heterostructured nanocatalysts were optimized and controlled step by step using strategies such as nano-sizing, surface carbonization, and in-situ surface growth.

[0010] A method for preparing a TiO2 / MnO2 heterostructured nanocatalyst includes the following steps;

[0011] Step 1: Nanoforming

[0012] Tetrabutyl titanate solution was added to a polytetrafluoroethylene liner and stirred. While stirring, hydrofluoric acid was added dropwise to the tetrabutyl titanate solution and stirred continuously. Then, it was placed in a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, it was washed by centrifugation with deionized water and anhydrous ethanol, then dried. The dried sample was placed in a muffle furnace for calcination. The final product was nano-TiO2.

[0013] Step 2: Surface carbonization

[0014] The nano-TiO2 synthesized in step 1 was added to a glucose solution, stirred, and then washed by centrifugation with deionized water and anhydrous ethanol. After drying, the dried sample was placed in a tube furnace and calcined under an Ar atmosphere. The calcined product was nano-TiO2@C. C, as a reducing agent, coated TiO2, thereby protecting TiO2 and reducing KMnO4 to MnO2.

[0015] Step 3: In-situ growth and synthesis of nano-TiO2 / MnO2 heterostructures

[0016] The nano-TiO2@C synthesized in step 2 was added to a potassium permanganate solution, stirred, and then placed in a hydrothermal reactor for a hydrothermal reaction. After the reaction was completed, the mixture was centrifuged and washed with deionized water, and then dried. The final product was the TiO2 / MnO2 nano-heterostructure catalyst. C and KMnO4 undergo a redox reaction, generating MnO2 in situ on the TiO2 surface.

[0017] In step 1, 20–40 mL of tetrabutyl titanate solution is added to a polytetrafluoroethylene liner and stirred. While stirring, 3–6 mL of hydrofluoric acid is added dropwise to the tetrabutyl titanate solution, and stirring is continued for 15–60 min. Then, the solution is placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 150–200 °C. After the reaction is completed, the solution is washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 60–100 °C for 6–12 h. The dried sample is then calcined in a muffle furnace at a temperature of 400–600 °C.

[0018] In step 2, the nano-TiO2 (1-2g) synthesized in step 1 is added to 100-200mL of glucose solution (0.02-0.06mol / L), stirred for 8-12h, washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 60-100℃ for 6-10h. The dried sample is placed in a tube furnace and calcined under Ar atmosphere at a temperature of 400-600℃.

[0019] In step 3, the nano-TiO2@C (1-2g) synthesized in step 2 is added to 40-80mL of potassium permanganate solution (0.003-0.01mol / L), stirred for 15-60min, and then placed in a hydrothermal reactor for hydrothermal reaction at 80-150℃. After the reaction is completed, the nano-TiO2@C is washed by centrifugation with deionized water and dried at 60-100℃ for 6-12h.

[0020] The TiO2 / MnO2 heterostructured nanocatalyst is used in magnesium-based hydrogen storage materials. The heterostructure not only increases the specific surface area and catalytic active sites, but also allows the Ti and Mn elements in TiO2 / MnO2 to chemically react with the Mg alloy matrix, promoting electron transfer and thus enhancing catalytic performance. Ti is beneficial for hydrogen release, while Mn is beneficial for hydrogen absorption.

[0021] The beneficial effects of this invention are:

[0022] This invention synthesizes and optimizes catalysts stepwise through strategies such as nano-sizing, surface carbonization, and in-situ surface growth. TiO2 nanoparticles are synthesized in one step using a hydrothermal method, then coated with a layer of C to impart high reducibility. This C then reacts with KMnO4 in a redox reaction to generate MnO2 in situ, forming a unique heterostructure that combines with TiO2. This invention leverages the catalytic characteristics of TiO2 and MnO2 in magnesium-based hydrogen storage materials to prepare a TiO2 / MnO2 heterostructure nanocatalyst. The catalyst obtained in this invention, with TiO2 as the main component, exhibits a unique nanostructure and a larger specific surface area compared to traditional commercial TiO2, thanks to the stepwise synthesis and optimization strategies involving nano-sizing, surface carbonization, and in-situ surface growth. Therefore, the TiO2 / MnO2 heterostructure nanocatalyst can achieve highly efficient catalytic performance in both hydrogen absorption and desorption processes of magnesium-based hydrogen storage materials. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation process of the TiO2 / MnO2 heterostructured nanocatalyst of the present invention.

[0024] Figure 2The images show the XRD pattern and SEM microstructure of the TiO2 / MnO2 heterostructure nanocatalyst of this invention.

[0025] Figure 3 The figure shows the hydrogen absorption and desorption performance of the TiO2 / MnO2 heterostructure nanocatalyst of this invention on Mg-Ni alloy. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] Example 1

[0028] The TiO2 / MnO2 heterostructure nanocatalyst of the present invention is composed of TiO2, accounting for >95 wt.%, with the remainder being in-situ grown MnO2.

[0029] Step 1, Nano-sizing: 25 mL of tetrabutyl titanate solution was added to a polytetrafluoroethylene liner and stirred. While stirring, 4.5 mL of hydrofluoric acid was added dropwise to the tetrabutyl titanate solution, and stirring continued for 30 min. Then, the solution was placed in a hydrothermal reactor and reacted at 180 °C for 24 h. After the reaction, the sample was washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 60 °C for 12 h. The dried sample was then calcined in a muffle furnace at 500 °C for 2 h, yielding nano-TiO2.

[0030] Step 2, Surface carbonization: The nano-TiO2 (1g) synthesized in Step 1 was added to 100mL of glucose solution (0.04mol / L), stirred for 12h, washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 60℃ for 10h. The dried sample was placed in a tube furnace and calcined under an Ar atmosphere at 500℃ for 2h. The product after calcination is nano-TiO2@C, where C acts as a reducing agent to coat TiO2, thus protecting TiO2 while reducing KMnO4 to MnO2.

[0031] Step 3, in-situ growth of nano-TiO2 / MnO2 heterostructure: The nano-TiO2@C (1g) synthesized in Step 2 was added to 40mL of potassium permanganate solution (0.005mol / L), stirred for 30min, and then placed in a hydrothermal reactor for hydrothermal reaction at 120℃ for 5h. After the reaction, it was washed by centrifugation with deionized water and dried at 60℃ for 12h. The final product is the TiO2 / MnO2 nano-heterostructure catalyst. C and KMnO4 undergo a redox reaction to generate MnO2 in situ on the TiO2 surface.

[0032] The TiO2 / MnO2 nano-heterostructure catalyst prepared in this embodiment is characterized by its small particle size, large specific surface area, and unique heterostructure that optimizes electron transport, thus providing excellent catalytic performance.

[0033] Example 2

[0034] The TiO2 / MnO2 heterostructure nanocatalyst of the present invention is composed of TiO2, accounting for >95 wt.%, with the remainder being in-situ grown MnO2.

[0035] Step 1, Nano-sizing: 20 mL of tetrabutyl titanate solution was added to a polytetrafluoroethylene liner and stirred. While stirring, 4 mL of hydrofluoric acid was added dropwise to the tetrabutyl titanate solution, and stirring continued for 15 min. Then, the solution was placed in a hydrothermal reactor and hydrothermally reacted at 160 °C for 30 h. After the reaction, the sample was washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 100 °C for 6 h. The dried sample was then calcined in a muffle furnace at 600 °C for 1 h, yielding nano-TiO2.

[0036] Step 2, Surface carbonization: The nano-TiO2 (2g) synthesized in Step 1 was added to 200mL of glucose solution (0.04mol / L), stirred for 6h, washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 100℃ for 6h. The dried sample was placed in a tube furnace and calcined under Ar atmosphere at 400℃ for 4h. The product after calcination is nano-TiO2@C, where C acts as a reducing agent to coat TiO2, protecting TiO2 while reducing KMnO4 to MnO2.

[0037] Step 3, in-situ growth of nano-TiO2 / MnO2 heterostructure: The nano-TiO2@C (2g) synthesized in Step 2 was added to 80mL of potassium permanganate solution (0.005mol / L), stirred for 15min, and then placed in a hydrothermal reactor for hydrothermal reaction at 140℃ for 4h. After the reaction, it was washed by centrifugation with deionized water and dried at 80℃ for 10h. The final product is the TiO2 / MnO2 nano-heterostructure catalyst. C and KMnO4 undergo a redox reaction to generate MnO2 in situ on the TiO2 surface.

[0038] The TiO2 / MnO2 nano-heterostructure catalyst prepared in this embodiment is characterized by its small particle size, large specific surface area, and unique heterostructure that optimizes electron transport, thus providing excellent catalytic performance.

[0039] Example 3

[0040] The TiO2 / MnO2 heterostructure nanocatalyst of the present invention is composed of TiO2, accounting for >95 wt.%, with the remainder being in-situ grown MnO2.

[0041] Step 1, Nano-sizing: 30 mL of tetrabutyl titanate solution was added to a polytetrafluoroethylene liner and stirred. While stirring, 5 mL of hydrofluoric acid was added dropwise to the tetrabutyl titanate solution, and stirring was continued for 60 min. Then, the solution was placed in a hydrothermal reactor and hydrothermally reacted at 200 °C for 20 h. After the reaction, the sample was washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 80 °C for 10 h. The dried sample was then calcined in a muffle furnace at 400 °C for 4 h, yielding nano-TiO2.

[0042] Step 2, Surface carbonization: The nano-TiO2 (1.5 g) synthesized in Step 1 was added to 150 mL of glucose solution (0.04 mol / L), stirred for 8 h, washed by centrifugation with deionized water and anhydrous ethanol, and then dried at 80 °C for 8 h. The dried sample was placed in a tube furnace and calcined under an Ar atmosphere at 600 °C for 1 h. The calcined product is nano-TiO2@C, where C acts as a reducing agent to coat TiO2, protecting TiO2 while reducing KMnO4 to MnO2.

[0043] Step 3, in-situ growth of nano-TiO2 / MnO2 heterostructure: The nano-TiO2@C (1.5g) synthesized in Step 2 was added to 60mL of potassium permanganate solution (0.005mol / L), stirred for 60min, and then placed in a hydrothermal reactor for hydrothermal reaction at 100℃ for 6h. After the reaction, it was washed by centrifugation with deionized water and dried at 100℃ for 8h. The final product is the TiO2 / MnO2 nano-heterostructure catalyst. C and KMnO4 undergo a redox reaction to generate MnO2 in situ on the TiO2 surface.

[0044] The TiO2 / MnO2 nano-heterostructure catalyst prepared in this embodiment is characterized by its small particle size, large specific surface area, and unique heterostructure that optimizes electron transport, thus providing excellent catalytic performance.

[0045] Figure 1 This is a process flow diagram of the TiO2 / MnO2 heterostructured nanocatalyst of the present invention. As can be seen from the flow diagram, the catalyst structure was finely controlled through strategies such as nano-sizing, surface carbonization, and in-situ growth, thereby obtaining a TiO2 / MnO2 heterostructured nanocatalyst with a large specific surface area, unique structure, and high catalytic activity.

[0046] Figure 2The images show the XRD and SEM images of the TiO2 / MnO2 heterostructure nanocatalyst of this invention. The XRD pattern shows that the main component of the material is TiO2, with peaks corresponding to MnO2 appearing in the TiO2 spectrum, proving that MnO2 was successfully introduced through in-situ synthesis. The SEM images show that the TiO2 / MnO2 heterostructure nanocatalyst exists in the form of square nanoparticles with a particle size between 10 and 40 nm, successfully achieving nanoscale treatment of the catalyst structure. The high specific surface area and unique heterostructure can provide more catalytic active sites for magnesium-based hydrogen storage materials.

[0047] Figure 3 This figure shows the hydrogen absorption and desorption performance of the TiO2 / MnO2 heterostructure nanocatalyst of the present invention on Mg-Ni alloys. As can be seen from the figure, the catalyst obtained in this invention exhibits excellent catalytic effect, enabling rapid hydrogen absorption and desorption in magnesium-based hydrogen storage materials. The catalytic mechanism lies in the fact that the TiO2 / MnO2 nanostructure provides a large number of catalytically active sites on the surface of the magnesium-based hydrogen storage material. Simultaneously, TiO2 and MnO2, through chemical bonding, synergistically modify the hydrogen absorption and desorption processes of the magnesium-based hydrogen storage material.

[0048] This invention employs optimized strategies such as nanostructuring, surface carbonization, and in-situ surface growth of TiO2 to prepare a TiO2 / MnO2 heterostructure nanocatalyst. This results in a unique morphology and structure with a large specific surface area, fully leveraging its catalytic advantages and enabling it to exhibit superior catalytic performance in magnesium-based hydrogen storage materials. Consequently, magnesium-based hydrogen storage materials achieve excellent hydrogen adsorption and desorption kinetics.

[0049] This invention successfully prepared TiO2 / MnO2 heterostructured nanocatalysts with unique structures and large specific surface areas using a multi-step, progressively optimized synthesis strategy. First, nano-TiO2 was successfully prepared using a combination of hydrothermal and high-temperature calcination methods to achieve nano-sizing. Second, surface carbonization was used for further optimization to prepare a TiO2@C coated structure, resulting in more dispersed nanoparticles. Simultaneously, the reducing properties of C provided the necessary conditions for subsequent in-situ surface growth. Finally, the TiO2 / MnO2 heterostructured nanocatalyst was prepared again using a combination of hydrothermal and high-temperature calcination methods, giving it a unique nanostructure. Studies show that Ti has a high binding force with H, which is beneficial for hydrogen release; while the binding force between Mn and H is weaker, which is beneficial for hydrogen absorption.

Claims

1. Use of a TiO2 / MnO2 heterostructure nanocatalyst, characterized in that, The TiO2 / MnO2 heterostructure nanocatalyst is used for catalyzing hydrogen absorption and hydrogen release of a magnesium-based hydrogen storage material, the heterostructure increases the specific surface area of the material and increases the catalytic active sites, meanwhile, the Ti element and the Mn element in the TiO2 / MnO2 chemically react with the Mg alloy matrix to promote the transfer of electrons and further increase the catalytic performance; The preparation method of the TiO2 / MnO2 heterostructure nanocatalyst comprises the following steps: Step 1: Nanocrystallization 20-40 mL of a tetrabutyl titanate solution is added to a polytetrafluoroethylene liner for stirring, while 3-6 mL of hydrofluoric acid is added dropwise into the tetrabutyl titanate solution, and the stirring is continued for 15-60 min, then it is placed in a hydrothermal kettle for hydrothermal reaction at 150-200 ℃; after the reaction is completed, it is centrifugally washed with deionized water and anhydrous ethanol, then it is dried at 60-100 ℃ for 6-12 h, and the dried sample is calcined in a muffle furnace, and the calcination temperature is 400-600 ℃; the final product is nano TiO2; Step 2: Surface carbonization 1-2 g of the nano TiO2 synthesized in step 1 is added to 100-200 mL of a 0.02-0.06 mol / L glucose solution, and after stirring for 8-12 h, it is centrifugally washed with deionized water and anhydrous ethanol, then it is dried at 60-100 ℃ for 6-10 h, and the dried sample is calcined in a tube furnace under the protection of Ar atmosphere, and the calcination temperature is 400-600 ℃; the calcined product is nano TiO2@C; Step 3: In-situ growth of nano TiO2 / MnO2 heterostructure The nano TiO2@C synthesized in step 2 is added to a potassium permanganate solution, and after stirring, it is placed in a hydrothermal kettle for hydrothermal reaction, and after the reaction is completed, it is centrifugally washed with deionized water and dried, and the final product is a TiO2 / MnO2 nanoheterostructure catalyst.

2. The use of a TiO2 / MnO2 heterostructure nanocatalyst according to claim 1, characterized in that, In step 3, 1-2 g of the nano TiO2@C synthesized in step 2 is added to 40-80 mL of a 0.003-0.01 mol / L potassium permanganate solution, and after stirring for 15-60 min, it is placed in a hydrothermal kettle for hydrothermal reaction at 80-150 ℃, and after the reaction is completed, it is centrifugally washed with deionized water and dried at 60-100 ℃ for 6-12 h.

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