A nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation and its preparation method
Nanoporous Ti/Ni heterojunctions were synthesized by electrolytic synergistic ultrasonic impregnation. By combining frequency-division ultrasonication and temperature-pressure synergistic regulation, the problems of limited mass transfer and hydrogen migration and agglomeration in the Mg/MgH2 system at room temperature were solved, realizing the preparation of efficient magnesium hydride hydrogen storage materials with excellent hydrogen storage performance and cycle stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIV
- Filing Date
- 2026-04-15
- Publication Date
- 2026-06-02
Smart Images
Figure CN122126798A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of advanced energy materials technology, specifically relating to a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation and its preparation method. Background Technology
[0002] Solid-state hydrogen storage technology, as one of the core directions for solving the challenges of hydrogen energy storage and transportation safety and efficiency, has always been a research focus in the new energy field. The Mg / MgH2 system, with its outstanding comprehensive advantages, has attracted widespread attention from academia and industry. This is due to its high mass hydrogen storage density (7.6 wt%), which can meet the long-term needs of on-board hydrogen storage. Furthermore, the abundance of magnesium resources, environmental friendliness, and relatively low cost make it a key breakthrough in solid-state hydrogen storage materials. However, ideal hydrogen storage materials, in addition to high hydrogen storage capacity, must also possess key performance indicators such as suitable operating temperature, controllable hydrogen absorption and desorption rates, and stable service life. The high thermodynamic stability of the Mg / MgH2 system means that the hydrogen absorption and desorption reactions must occur at relatively high temperatures, making it difficult to adapt to practical applications at room temperature or medium to low temperatures. Simultaneously, its slow kinetic performance means that its hydrogen absorption and desorption rates cannot meet the requirements for rapid hydrogen charging and discharging. These two core problems seriously hinder the commercialization of the Mg / MgH2 system.
[0003] To overcome the aforementioned technical bottlenecks, researchers have developed various modification strategies, among which adding transition metal catalysts to the Mg / MgH2 system has proven to be the simplest and most efficient modification method. Among numerous transition metal catalysts, Ni and Ti exhibit excellent modification effects due to their unique catalytic mechanisms. Studies have shown that Ni can react with Mg to form Mg2NiH4 / Mg2Ni, simultaneously promoting hydrogen molecule dissociation and hydrogen atom transport through a "hydrogen pump" mechanism; while Ti's multivalent state characteristics can... 2+ The ions act as electron transfer bridges between the ions and H atoms, providing more active catalytic sites. Based on the synergistic catalytic effect of the two, constructing a Ti / Ni heterojunction interface by combining Ti and Ni can induce interfacial charge reconstruction, forming a local electric field, further optimizing the adsorption and dissociation behavior of hydrogen molecules, and realizing the synergistic catalysis of hydrophilic titanium and hydrophobic nickel.
[0004] Meanwhile, studies have shown that confining MgH2 within nanopores (nanoporation) can significantly increase the specific surface area, shorten the hydrogen diffusion path, and effectively suppress grain growth during cycling. Therefore, constructing Ti / Ni heterojunctions with nanoporous structures as catalysts and supports for MgH2 is expected to fully leverage the synergistic effect of nanoconfinement and interfacial catalysis, overcoming the performance limitations of single modification strategies. Among these methods, the dibutylmagnesium precursor method has attracted attention due to its unique advantages: utilizing the solubility of dibutylmagnesium in organic solvents, it is introduced into the porous framework channels through liquid-phase impregnation, and then high-pressure hydrogenation under mild conditions generates highly active nanocrystalline MgH2 in situ.
[0005] However, several key technical challenges remain when applying the dibutylmagnesium precursor method to nanoporous Ti / Ni heterojunctions. First, mass transfer is limited during the impregnation process. Nanoporous Ti / Ni heterojunctions possess abundant mesoporous structures. During conventional static impregnation, the dibutylmagnesium solution is affected by capillary action and diffusion resistance, making it difficult to uniformly fill deep pores, resulting in low loading and uneven distribution. Second, MgH2 migration and agglomeration occur during hydrogenation. The dibutylmagnesium hydrogenation reaction is exothermic; localized temperature rises lead to vigorous reactions, causing the generated MgH2 nanocrystals to easily migrate from the pores to the heterojunction surface, crystallizing and agglomerating to form a dense capping layer. This not only blocks the pore entrances but also causes a large amount of MgH2 to lose its nano-confinement effect. Third, the reaction process is poorly controlled. Existing hydrogenation processes mostly employ isothermal and isobaric modes, failing to finely control the kinetic characteristics of the dibutylmagnesium hydrogenation reaction, making it difficult to balance the dual requirements of avoiding excessively rapid decomposition in the early stages of the reaction and ensuring complete conversion in the later stages.
[0006] Therefore, it is necessary to design a nanoporous heterostructure-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation and its preparation method. Summary of the Invention
[0007] To overcome the shortcomings of existing technologies, this paper provides a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation and its preparation method.
[0008] To achieve the above objectives, the present invention provides the following technical solution: A method for synthesizing a nanoporous heterojunction-loaded magnesium hydride composite hydrogen storage material by electrolytic synergistic ultrasonic impregnation, the material comprising a nanoporous heterojunction and magnesium hydride loaded therein; the nanoporous heterojunction comprises at least two metals, wherein at least one metal has hydrogen-loving properties and the other at least one metal has hydrogen-repellent properties, and the different metals are combined to form a heterojunction interface.
[0009] The nanoporous metal heterostructure has a pore size distribution of 5-100 nm, a porosity ≥50%, and a specific surface area ≥30 m². 2 / g.
[0010] A method for synthesizing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material by electrolytic synergistic ultrasonic impregnation, the method comprising the following steps: Step 1: Metal A and metal B are mixed and melted, and after hot isostatic pressing, isothermal forging, grinding and leveling, an AB alloy is obtained. The AB alloy is placed in an electrolytic solution and dealloyed by electrochemical selective dissolution to construct a nanoporous A / B heterostructure in situ. After washing and drying, a nanoporous metal heterostructure is obtained. Step 2: Place the nanoporous metal heterostructure obtained in Step 1 into a reaction vessel and add a dibutylmagnesium solution; place the reaction vessel in an ultrasonic bath and apply ultrasound at the first frequency for assisted impregnation; after the ultrasound is completed, let it stand and soak at the same temperature; then filter to remove excess solution to obtain the composite precursor loaded with dibutylmagnesium. Step 3: Quickly transfer the precursor obtained in Step 2 to a high-pressure reactor and seal it under an inert atmosphere; purge the atmosphere inside the reactor with high-purity hydrogen 3-5 times; set the initial hydrogen pressure and turn on the heating and ultrasonic devices; apply second-frequency ultrasound for assisted hydrogenation; increase the temperature in stages according to the programmed heating method and simultaneously perform dynamic pressure control; after the reaction is completed, allow it to cool naturally to room temperature to obtain the crude product. Step 4: Place the crude product obtained in Step 3 in a vacuum glove box and wash it 2-3 times with an organic solvent; then vacuum dry it; finally, remove the crystalline material distributed on the surface of the heterojunction by mechanical peeling to obtain a pure nanoporous alloy heterojunction supported magnesium hydride composite material.
[0011] In step one, metal A in the nanoporous metal heterostructure is at least one of Ti, V, and Zr, and metal B is at least one of Ni, Fe, Co, and Cu.
[0012] In step one, the nanoporous metal heterostructure is selected from one of the following combinations: Ti / Ni heterojunction, Ti:Ni atomic ratio 1:0.5-1:2; Ti / Fe heterojunction, Ti:Fe atomic ratio 1:0.5-1:2; V / Ni heterojunction, V:Ni atomic ratio 1:0.5-1:2; Zr / Co heterojunction, Zr:Co atomic ratio 1:0.5-1:2; Ti / Ni / Fe ternary heterostructure, with Ti:Ni:Fe atomic ratio of 1:0.3-1:0.3-1.
[0013] In step one, the electrolyte solution is an alkaline electrolyte or an acidic electrolyte; The concentration of the electrolyte solution is 0.1-5 M; the alkaline electrolyte solution is NaOH solution or KOH solution; the acidic electrolyte solution is H2SO4 solution or HCl solution. The process parameters for the electrochemical selective dissolution are: electrode voltage 0.5-5 V, polarization time 10-120 minutes, and electrolysis temperature 20-80℃. The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃. The washing process involves alternating between deionized water and anhydrous ethanol for 3-5 times. The drying process is vacuum drying, at a temperature of 40-80℃, for 2-6 hours.
[0014] In step two, the solid-liquid ratio of the nanoporous metal heterostructure to the dibutylmagnesium solution is 1:5-1:20 (g:mL). The concentration of the dibutylmagnesium solution is 0.5-1.5 M, and its solvent is heptane or hexane; The frequency of the first frequency ultrasound is 20-40 kHz; the power of the first frequency ultrasound is 100-300 W; the processing temperature of the first frequency ultrasound is 0-25℃; and the processing time of the first frequency ultrasound is 30-120 minutes. The soaking time is 2-6 hours.
[0015] In step three, the purity of the high-purity hydrogen gas is ≥99.999%; The initial hydrogen pressure is 1-3 MPa; The frequency of the second frequency ultrasound is 60-100 kHz; the power of the second frequency ultrasound is 50-200 W. The programmed heating method is as follows: heat up to the first temperature range of 80-120℃ at a rate of 1-5℃ / min, hold for 30-60 minutes; then continue to heat up to the second temperature range of 150-200℃ at a rate of 1-5℃ / min, hold for 60-120 minutes. The dynamic pressure control is as follows: when the temperature rises to the second temperature range, the hydrogen pressure is simultaneously adjusted from the initial pressure to 3-8 MPa; the dynamic pressure control is a linear pressurization mode with a pressurization rate of 0.05-0.1 MPa / min.
[0016] In step four, the organic solvent is anhydrous heptane or hexane; The vacuum drying conditions are 40-60℃ for 2-4 hours; The mechanical peeling method is slight abrasion or airflow purging.
[0017] An insertion-type ultrasonic probe is installed inside the high-pressure reactor; both the first and second frequency ultrasonic probes adopt pulse mode with a duty cycle of 30-70%. In step two, repeat the "ultrasonic-assisted impregnation-static soaking" cycle 2-3 times, and dry to remove the solvent after each cycle; The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃.
[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This application provides a method for synthesizing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material via electrolytic synergistic ultrasonic impregnation. The structural design of the nanoporous heterojunction allows direct contact between a hydrophilic metal and a hydrophores metal at the nanoscale, inducing charge reconstruction and forming a local electric field at the interface, thereby optimizing the adsorption and dissociation behavior of hydrogen molecules. Compared with single metal catalysis or simple physical mixing, the presence of the heterojunction interface can simultaneously exert the affinity adsorption of hydrogen molecules by the hydrophilic metal and the catalytic effect of hydrogen molecule dissociation by the hydrophores metal, forming a synergistic catalytic effect. Simultaneously, the confined space provided by the nanoporous structure restricts magnesium hydride to pores with a diameter of 5 to 100 nanometers, increasing the specific surface area of magnesium hydride, shortening the diffusion path of hydrogen atoms, and effectively suppressing grain growth of magnesium hydride during hydrogen adsorption and desorption cycles.
[0019] 2. In the preparation of this composite material, this application employs frequency-division ultrasonic assistance to enhance both the impregnation and hydrogenation steps. Addressing the mass transfer limitation issue inherent in conventional static impregnation of the rich mesoporous structure of the nanoporous heterostructure, this application applies first-frequency ultrasound for assisted impregnation during the impregnation step. When the nanoporous metal heterostructure and dibutylmagnesium solution are placed together in an ultrasonic bath, the cavitation effect and microjets generated by the first-frequency ultrasound effectively reduce the diffusion resistance at the liquid-solid interface, enabling the dibutylmagnesium solution to overcome capillary forces and fill more uniformly into the deep pores. Simultaneously, the ultrasonic action improves wettability within the pores, preventing air embolism caused by surface tension, thereby achieving a high loading and uniform distribution of dibutylmagnesium within the nanoporous structure. Compared to simple static impregnation, ultrasonic-assisted impregnation allows for more complete filling of the precursor within the pores, providing a uniform magnesium source distribution for the subsequent hydrogenation reaction.
[0020] 3. In the hydrogenation reaction stage, this application applies a second-frequency ultrasound at a different frequency than that used in the impregnation step for assisted hydrogenation. The hydrogenation reaction of dibutylmagnesium is an exothermic reaction. In conventional processes, local temperature rises can easily lead to violent reactions, and the generated magnesium hydride nanocrystals tend to migrate from the inside of the pores to the surface of the heterojunction and crystallize and agglomerate, forming a dense capping layer. This application introduces a second-frequency ultrasound during the hydrogenation process, utilizing the micro-perturbation effect and acoustic flow generated by higher-frequency ultrasound to microscopically control the temperature and concentration fields at the reaction interface, avoiding reaction runaway due to local overheating. At the same time, the ultrasound action can promote the in-situ transformation of reaction intermediates inside the pores, reducing the tendency of magnesium hydride to migrate to the outside of the pores, thereby inhibiting the formation of surface crystals. Through the synergistic effect of frequency-divided ultrasound, a lower frequency is used in the impregnation stage to focus on enhancing mass transfer, while a higher frequency is used in the hydrogenation stage to focus on controlling the reaction process, achieving targeted enhancement of both steps.
[0021] 4. This application also employs a refined control method combining programmed temperature rise and dynamic pressure regulation during the hydrogenation reaction. Considering the differences in kinetic characteristics of the dibutylmagnesium hydrogenation reaction at different temperature stages, this application sets up a staged temperature rise mode. First, dibutylmagnesium is initially hydrogenated in a lower temperature range to avoid violent decomposition caused by excessively rapid temperature rise in the early stages of the reaction. Then, the hydrogenation reaction is ensured to proceed completely in a higher temperature range. Simultaneously, pressure regulation is implemented when the temperature reaches the higher temperature range, gradually increasing the hydrogen pressure from the initial value to a higher pressure. This pressure change further promotes the hydrogenation reaction towards the formation of magnesium hydride. This temperature-pressure coordinated dynamic regulation method can balance the dual requirements of avoiding excessively rapid decomposition in the early stages of the reaction and ensuring complete conversion in the later stages, thereby improving the conversion efficiency of dibutylmagnesium to magnesium hydride. Finally, a small amount of crystalline material that may exist on the surface of the heterojunction is removed by mechanical exfoliation to obtain a pure nanoporous alloy heterojunction-supported magnesium hydride composite material. Detailed Implementation
[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] The technical solution of this application is as follows: A nanoporous heterojunction-loaded magnesium hydride composite hydrogen storage material prepared by electrolytic synergistic ultrasonic impregnation, the material comprising a nanoporous heterojunction and magnesium hydride loaded therein; the nanoporous heterojunction comprises at least two metals, wherein at least one metal has hydrogen-loving properties and the other at least one metal has hydrogen-repellent properties, and the different metals are combined to form a heterojunction interface.
[0024] The nanoporous metal heterostructure has a pore size distribution of 5-100 nm, a porosity ≥50%, and a specific surface area ≥30 m². 2 / g.
[0025] A method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material by electrolytic synergistic ultrasonic impregnation, the method comprising the following steps: Step 1: Metal A and metal B are mixed and melted, and after hot isostatic pressing, isothermal forging, grinding and leveling, an AB alloy is obtained. The AB alloy is placed in an electrolytic solution and dealloyed by electrochemical selective dissolution to construct a nanoporous A / B heterostructure in situ. After washing and drying, a nanoporous metal heterostructure is obtained. Step 2: Place the nanoporous metal heterostructure obtained in Step 1 into a reaction vessel and add a dibutylmagnesium solution; place the reaction vessel in an ultrasonic bath and apply ultrasound at the first frequency for assisted impregnation; after the ultrasound is completed, let it stand and soak at the same temperature; then filter to remove excess solution to obtain the composite precursor loaded with dibutylmagnesium. Step 3: Quickly transfer the precursor obtained in Step 2 to a high-pressure reactor and seal it under an inert atmosphere; purge the atmosphere inside the reactor with high-purity hydrogen 3-5 times; set the initial hydrogen pressure and turn on the heating and ultrasonic devices; apply second-frequency ultrasound for assisted hydrogenation; increase the temperature in stages according to the programmed heating method and simultaneously perform dynamic pressure control; after the reaction is completed, allow it to cool naturally to room temperature to obtain the crude product. Step 4: Place the crude product obtained in Step 3 in a vacuum glove box and wash it 2-3 times with an organic solvent; then vacuum dry it; finally, remove the crystalline material distributed on the surface of the heterojunction by mechanical peeling to obtain a pure nanoporous alloy heterojunction supported magnesium hydride composite material.
[0026] Regarding the preparation process of MgH2 loaded in nanoporous Ti / Ni heterojunctions, this invention achieves precise and uniform loading of MgH2 in nanopores by using "lower frequency ultrasonic-assisted impregnation followed by higher frequency ultrasonic-assisted hydrogenation" combined with dynamic pressure-temperature synergistic control. This fully leverages the interfacial catalytic effect of the Ti / Ni heterojunction and the confinement effect of the nanopores to obtain MgH2@Ti / Ni composite materials with excellent comprehensive hydrogen storage performance.
[0027] In step one, metal A in the nanoporous metal heterostructure is at least one of Ti, V, and Zr, and metal B is at least one of Ni, Fe, Co, and Cu.
[0028] In step one, the nanoporous metal heterostructure is selected from one of the following combinations: Ti / Ni heterojunction, Ti:Ni atomic ratio 1:0.5-1:2; Ti / Fe heterojunction, Ti:Fe atomic ratio 1:0.5-1:2; V / Ni heterojunction, V:Ni atomic ratio 1:0.5-1:2; Zr / Co heterojunction, Zr:Co atomic ratio 1:0.5-1:2; Ti / Ni / Fe ternary heterostructure, with Ti:Ni:Fe atomic ratio of 1:0.3-1:0.3-1.
[0029] This invention constructs a Ti / Ni heterostructure nanoporous framework. Utilizing the difference in electrochemical activity between Ti and Ni, a Ti / Ni heterostructure with high specific surface area and abundant nanopores is prepared by electrolytic etching. This framework possesses both catalytic function (Ti / Ni interface synergistic catalysis of hydrogen dissociation) and confinement function (physical confinement of MgH2 within nanopores).
[0030] In step one, the electrolyte solution is an alkaline electrolyte or an acidic electrolyte; The concentration of the electrolyte solution is 0.1-5 M; the alkaline electrolyte solution is NaOH solution or KOH solution; the acidic electrolyte solution is H2SO4 solution or HCl solution. The process parameters for the electrochemical selective dissolution are: electrode voltage 0.5-5 V, polarization time 10-120 minutes, and electrolysis temperature 20-80℃. The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃. The washing process involves alternating between deionized water and anhydrous ethanol for 3-5 times. The drying process is vacuum drying, at a temperature of 40-80℃, for 2-6 hours.
[0031] In step two, the solid-liquid ratio of the nanoporous metal heterostructure to the dibutylmagnesium solution is 1:5-1:20 (g:mL). The concentration of the dibutylmagnesium solution is 0.5-1.5 M, and its solvent is heptane or hexane; The frequency of the first frequency ultrasound is 20-40 kHz; the power of the first frequency ultrasound is 100-300 W; the processing temperature of the first frequency ultrasound is 0-25℃; and the processing time of the first frequency ultrasound is 30-120 minutes. The soaking time is 2-6 hours.
[0032] In step three, the purity of the high-purity hydrogen gas is ≥99.999%; The initial hydrogen pressure is 1-3 MPa; The frequency of the second frequency ultrasound is 60-100 kHz; the power of the second frequency ultrasound is 50-200 W. The programmed heating method is as follows: heat up to the first temperature range of 80-120℃ at a rate of 1-5℃ / min, hold for 30-60 minutes; then continue to heat up to the second temperature range of 150-200℃ at a rate of 1-5℃ / min, hold for 60-120 minutes. The dynamic pressure control is as follows: when the temperature rises to the second temperature range, the hydrogen pressure is simultaneously adjusted from the initial pressure to 3-8 MPa; the dynamic pressure control is a linear pressurization mode with a pressurization rate of 0.05-0.1 MPa / min.
[0033] This invention introduces a dynamic pressure-temperature coordinated control mechanism. The hydrogenation process adopts a programmed temperature increase combined with a linear pressurization mode: first, dibutylmagnesium is initially converted in a low temperature and low pressure stage to form an "anchor point"; then, the pressure is increased simultaneously with the temperature increase to ensure that the hydrogenation reaction proceeds smoothly and to prevent MgH2 from being "rushed out" of the pores by a violent reaction.
[0034] In step four, the organic solvent is anhydrous heptane or hexane; The vacuum drying conditions are 40-60℃ for 2-4 hours; The mechanical peeling method is slight abrasion or airflow purging.
[0035] An insertion-type ultrasonic probe is installed inside the high-pressure reactor; both the first and second frequency ultrasonic probes are in pulse mode with a duty cycle of 30-70%; the first frequency ultrasonic probe (lower: 20-40 kHz) mainly generates cavitation effect and microjets, which can significantly promote the permeation of liquid in porous media; the second frequency ultrasonic probe (higher: 60-100 kHz) has a significant sonochemical effect, which can accelerate the dissociation of hydrogen molecules and chemical reactions.
[0036] In step two, repeat the "ultrasonic-assisted impregnation-static soaking" cycle 2-3 times, and dry to remove the solvent after each cycle; The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃.
[0037] This invention constructs a nanoporous heterostructure-supported magnesium hydride composite material that combines interfacial catalytic synergy with nanoconfinement effect, and combines frequency-division ultrasonic-assisted impregnation with temperature-pressure synergistic dynamic hydrogenation process to achieve high-load uniform distribution and in-situ controllable conversion of magnesium hydride in nanopores.
[0038] The present invention will be described in detail below with reference to examples, comparative examples, and accompanying drawings, but the scope of protection of the present invention is not limited to these examples. Unless otherwise specified, the chemical reagents and raw materials used in the following examples and comparative examples are all conventional commercially available products. Attached Figure Description
[0039] Figure 1 Scanning electron microscope image of the nanoporous Ti / Ni heterostructure obtained in Example 1. Figure 2 The hydrogen absorption curve of the MgH2@Ti / Ni composite material obtained in Example 1 at 150℃ Figure 3 The hydrogen desorption curve of the MgH2@Ti / Ni composite material obtained in Example 1 at 250℃. Figure 4 The hydrogen adsorption / desorption cycle curve of the MgH2@Ti / Ni composite material obtained in Example 1 after 50 cycles is shown. Example 1: Ti / Ni heterojunction (Ti:Ni=1:1) (1) Titanium powder and nickel powder were mixed and smelted at an atomic ratio of Ti:Ni = 1:1. After hot isostatic pressing, isothermal forging, grinding and smoothing, Ti-Ni alloy sheets were obtained. The Ti-Ni alloy was placed in 1 M NaOH electrolyte, with the alloy as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. A voltage of 2 V was applied, and electrolysis was carried out at 50 °C for 60 minutes. After the reaction, the mixture was washed three times alternately with deionized water and anhydrous ethanol, and then vacuum dried at 50 °C for 4 hours to obtain nanoporous Ti / Ni heterojunctions. Characterization showed that the pore size was 20-50 nm and the specific surface area was 68 m². 2 / g, porosity 65%, such as Figure 1 As shown, a uniformly distributed nanoscale porous structure is formed on the surface of the Ti / Ni heterojunction, indicating that a dealloying process was achieved during electrolysis. Mechanism analysis suggests that the voltage exceeds the dissolution potential of Ti, but may still be lower than the dissolution potential of Ni. Titanium acts as the active component, with Ti... 3+ / Ti 4+ The inert form preferentially dissolves into the acidic electrolyte, while Ni remains in situ and rearranges through surface diffusion, self-assembling to form a bicontinuous nanoporous framework. This structure constitutes an ideal Ti / Ni heterojunction interface, whose high specific surface area and abundant interfacial active sites are extremely beneficial for the subsequent catalytic process of magnesium-based hydrogen storage.
[0040] (2) Take 1.0 g of the above nanoporous Ti / Ni heterojunction, dry it in vacuum at 100℃ for 3 hours, and cool it under argon protection for later use.
[0041] (3) Place the dried heterojunction in a reaction flask and add 10 mL of a 1.0 M dibutylmagnesium heptane solution (solid-liquid ratio 1:10); place the reaction flask in an ultrasonic cleaning tank, apply 30 kHz ultrasound at 200 W, cool in an ice-water bath to maintain the temperature at 10±2℃, and sonicate for 60 minutes; then let it stand and soak for 4 hours; filter to remove the solution and obtain the precursor loaded with dibutylmagnesium.
[0042] (4) Quickly transfer the precursor to a 50 mL high-pressure reactor and seal it under argon protection; purge with high-purity hydrogen (99.999%) three times; set the initial hydrogen pressure to 2 MPa; turn on the insertion ultrasonic probe and apply 80 kHz ultrasound at a power of 100 W with a pulse mode duty cycle of 50%; raise the temperature to 100℃ at 2℃ / min and hold for 45 minutes; then continue to raise the temperature to 180℃ at 2℃ / min, while simultaneously starting linear pressurization, increasing the pressure uniformly from 2 MPa to 6 MPa (pressurization rate of approximately 0.067 MPa / min), and hold at 180℃ for 90 minutes; after the reaction is complete, allow it to cool naturally, release the gas, and remove the product.
[0043] (5) The crude product was washed twice with anhydrous heptane in a glove box, 5 mL each time; dried under vacuum at 50°C for 3 hours; then it was lightly ground for 2 minutes under a weak argon gas purging to remove surface crystals and obtain the final product MgH2@Ti / Ni.
[0044] (6) Performance characterization Hydrogen storage capacity: at 250℃ and 3 MPa hydrogen pressure, the reversible hydrogen storage capacity is 3.2 wt% (based on the total mass of composite materials). Hydrogen absorption kinetics: At 150℃, 1.5 wt% hydrogen is absorbed in 1 minute and 3.0 wt% in 5 minutes. Figure 2 As shown, from Figure 2 It can be seen that under a hydrogen atmosphere of 150 ℃ and 3 MPa, MgH2@Ti / Ni Composite materials The material exhibits exceptionally high hydrogen absorption kinetics. In the initial hydrogen absorption phase, it reaches a hydrogen capacity of 1.5 wt% within 1 minute, demonstrating a rapid, high-rate response. Subsequently, the hydrogen absorption capacity rapidly increases to 3.0 wt% within 5 minutes, further confirming its rapid hydrogen diffusion and surface permeation capabilities. The extremely low activation energy required for this process indicates a significantly reduced dissociation and adsorption barrier for hydrogen molecules on the material surface, allowing hydrogen atoms to easily enter the lattice or interface sites, thus achieving a rapid hydrogenation reaction. This extremely low activation energy and short-duration, high-capacity hydrogen absorption behavior make this material highly promising for applications in rapid hydrogen storage and responsive hydrogen energy systems.
[0045] Hydrogen release kinetics: 2.9 wt% hydrogen is released in 5 minutes at 250°C. Figure 3The hydrogen desorption curve of the MgH2@Ti / Ni composite material obtained in Example 1 at 250℃ is shown below. Figure 1 As can be seen, the MgH2@Ti / Ni heterojunction composite material exhibits excellent kinetic performance during hydrogen storage and desorption. During hydrogen desorption, 2.9 wt% of hydrogen is released within 5 minutes, further increasing to 3.2 wt% within 10 minutes, achieving highly efficient hydrogen desorption. On one hand, the nanoscale confinement space constructed by the Ti / Ni components confines the MgH2 particles to the nanoscale, effectively shortening the diffusion path of hydrogen atoms and inhibiting aggregation and growth during cycling. On the other hand, the Ti / Ni heterojunction interface provides abundant catalytic active sites; Ti promotes rapid diffusion of hydrogen atoms, while Ni acts as a "hydrogen pump," lowering the energy barrier for breaking the Mg-H bond. The coupling effect of confinement and catalysis significantly reduces the activation energy for hydrogen absorption and desorption, enabling the composite material to possess high capacity, fast response, and good cycling stability, providing an effective strategy for developing high-performance magnesium-based hydrogen storage materials.
[0046] Cyclic stability: 91% capacity retention after 50 cycles, such as... Figure 4 As shown, after 50 hydrogen adsorption / desorption cycles, the composite material maintained a capacity retention of 91%, and its excellent cycling stability is also attributed to the synergistic effect of confinement and Ti / Ni catalysis. The nanoscale confinement space constructed by the Ti / Ni components effectively confines the MgH2 particles, preventing them from agglomerating and coarsening during repeated hydrogen adsorption / desorption, thereby suppressing structural factors that cause capacity decay. The bimetallic heterojunction interface maintains stable catalytic activity during cycling, continuously reducing the Mg-H bond breaking energy barrier and avoiding kinetic degradation caused by catalyst deactivation or agglomeration. The synergistic effect of both ensures that the material can maintain rapid and efficient hydrogen adsorption / desorption performance even during long-term cycling.
[0047] Example 2: V / Ni heterojunction (V:Ni=1:1) Except for step 1, where vanadium powder and nickel powder were mixed and smelted at an atomic ratio of V:Ni = 1:1 to prepare the V-Ni alloy, and the electrolyte was changed to 0.5 M H₂SO₄, the electrolysis voltage was 1.5 V, and the electrolysis time was 45 minutes, the other conditions were the same as in Example 1. The resulting nanoporous V / Ni heterojunction had a pore size of 10-60 nm and a specific surface area of 55 m². 2 / g. The final product MgH2@V / Ni has a hydrogen storage capacity of 3.0 wt% and a retention rate of 86% after 50 cycles.
[0048] Example 3: Zr / Co heterojunction (Zr:Co=1:1.5) Except for step 1, where zirconium powder and cobalt powder were mixed and smelted at an atomic ratio of Zr:Co = 1:1.5 to prepare the Zr-Co alloy, and the electrolyte was changed to 1 M KOH, the electrolysis voltage was 2.5 V, and the electrolysis time was 80 minutes, all other conditions were the same as in Example 1. The resulting nanoporous Zr / Co heterojunction had a pore size of 10-50 nm and a specific surface area of 48 m². 2 / g. The hydrogen storage capacity of the final product MgH2@Zr / Co is 2.8 wt%.
[0049] Example 4: Ti / Fe heterojunction (Ti:Fe=1:0.8) Except for step 1, where titanium powder and iron powder were mixed and smelted at an atomic ratio of Ti:Fe = 1:0.8 to prepare the Ti-Fe alloy, and the electrolyte was changed to 0.3 M HCl, the electrolysis voltage was 1.2 V, and the electrolysis time was 40 minutes, all other conditions were the same as in Example 1. The resulting nanoporous Ti / Fe heterostructure had a pore size of 15-45 nm and a specific surface area of 52 m². 2 / g. The hydrogen storage capacity of the final product MgH2@Ti / Fe is 2.6wt%.
[0050] Example 5: Ti / Ni / Fe ternary heterojunction (Ti:Ni:Fe=1:0.5:0.5) Except for step 1, where titanium powder, nickel powder, and iron powder were mixed and smelted in an atomic ratio of Ti:Ni:Fe = 1:0.5:0.5 to prepare the Ti-Ni-Fe ternary alloy, and the electrolyte was 1 M NaOH, the electrolysis voltage was 2.2 V, and the electrolysis time was 70 minutes, all other conditions were the same as in Example 1. The resulting nanoporous Ti / Ni / Fe heterostructure had a pore size of 10-40 nm and a specific surface area of 62 m². 2 / g. The final product MgH2@Ti / Ni / Fe has a hydrogen storage capacity of 3.1 wt% and a retention rate of 89% after 50 cycles.
[0051] Comparative Example 1 (Single low-frequency ultrasound throughout the entire process) Except for the impregnation and hydrogenation stages, which were conducted entirely using 30 kHz ultrasound, the other conditions were the same as in Example 1. Results: Hydrogen storage capacity of 1.2 wt%. TEM showed that a large amount of MgH2 agglomerated into 100-200 nm particles on the surface of the heterojunction, blocking the pores.
[0052] Comparative Example 2 (Single high-frequency ultrasound throughout the entire process) Except for the impregnation and hydrogenation stages, which were conducted entirely using 80 kHz ultrasound, the other conditions were the same as in Example 1. Results: In the impregnation stage, dibutylmagnesium permeation was insufficient, resulting in low loading within the pores and a hydrogen storage capacity of only 1.0 wt%.
[0053] Comparative Example 3 (without ultrasound assistance) Except for the absence of any ultrasound, the conditions were the same as in Example 1. Results: uneven impregnation, incomplete hydrogenation, hydrogen storage capacity of 0.65 wt%, and a large amount of organic residue.
[0054] Comparative Example 4 (Constant Pressure Hydrogenation) Except for maintaining a constant pressure of 4 MPa during the hydrogenation process and not increasing the pressure in stages, the other conditions were the same as in Example 1. Results: The reaction was vigorous in the initial stage, with some MgH2 being flushed out of the pores and severe surface aggregation. The hydrogen storage capacity was 1.6 wt%.
[0055] Comparative Example 5 (Non-heterojunction single metal) Nanoporous Ni material (Ti-free) was used instead of the Ti / Ni heterojunction, and the other conditions were the same as in Example 1. Results: Hydrogen storage capacity was 1.2 wt%, and the retention rate after 50 cycles was 75%, indicating the lack of synergistic catalytic effect at the heterojunction interface.
[0056] The composite material prepared by the method of this invention was observed by TEM to show that MgH2 was mainly distributed inside the 10-50 nm pores, with no obvious agglomeration layer on the surface, thus achieving precise loading of MgH2 in the nanopores.
[0057] PCT testing showed that the composite material prepared in this invention has a reversible hydrogen storage capacity of 2.5-3.2 wt% at 250℃ and 3 MPa hydrogen pressure, which is significantly better than the comparative example. Among them, the optimal hydrogen storage capacity of the Ti / Ni heterojunction composite material can reach 3.2 wt%.
[0058] Hydrogen absorption performance: At 150℃, it can absorb 95% of the capacity within 5 minutes and completely absorb it within 10 minutes; Hydrogen release performance: At 250℃, it can completely release hydrogen within 10 minutes; It is more than 100℃ lower than pure MgH2.
[0059] After 50 hydrogen adsorption / desorption cycles, the capacity retention of the Ti / Ni heterojunction composite material is >90%.
[0060] The method of this invention is not only applicable to Ti / Ni heterojunctions, but can also be extended to various metal combinations (V / Ni, Zr / Co, Ti / Fe, Ti / Ni / Fe, etc.), and has good versatility.
[0061] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation, characterized in that, The material comprises a nanoporous heterostructure and magnesium hydride loaded therein; the nanoporous heterostructure comprises at least two metals, wherein at least one metal has hydrogen-loving properties and the other at least one metal has hydrogen-repellent properties, and the different metals are combined to form a heterostructure interface.
2. The nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 1, characterized in that, The nanoporous metal heterostructure has a pore size distribution of 5-100 nm, a porosity of ≥50%, and a specific surface area of ≥30 m² / g.
3. A method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation as described in claim 1 or 2, characterized in that, The method includes the following steps: Step 1: Metal A and metal B are mixed and melted, and after hot isostatic pressing, isothermal forging, grinding and leveling, an AB alloy is obtained. The AB alloy is placed in an electrolytic solution and dealloyed by electrochemical selective dissolution to construct a nanoporous A / B heterostructure in situ. After washing and drying, a nanoporous metal heterostructure is obtained. Step 2: Place the nanoporous metal heterostructure obtained in Step 1 into a reaction vessel and add a dibutylmagnesium solution; place the reaction vessel in an ultrasonic bath and apply ultrasound at the first frequency for assisted impregnation; after the ultrasound is completed, let it stand and soak at the same temperature; then filter to remove excess solution to obtain the composite precursor loaded with dibutylmagnesium. Step 3: Quickly transfer the precursor obtained in Step 2 to a high-pressure reactor and seal it under an inert atmosphere; purge the atmosphere inside the reactor with high-purity hydrogen 3-5 times; set the initial hydrogen pressure and turn on the heating and ultrasonic devices; apply second-frequency ultrasound for assisted hydrogenation; increase the temperature in stages according to the programmed heating method and simultaneously perform dynamic pressure control; after the reaction is completed, allow it to cool naturally to room temperature to obtain the crude product. Step 4: Place the crude product obtained in Step 3 in a vacuum glove box and wash it 2-3 times with an organic solvent; then vacuum dry it; finally, remove the crystalline material distributed on the surface of the heterojunction by mechanical peeling to obtain a pure nanoporous alloy heterojunction supported magnesium hydride composite material.
4. The preparation method of a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, In step one, metal A in the nanoporous metal heterostructure is at least one of Ti, V, and Zr, and metal B is at least one of Ni, Fe, Co, and Cu.
5. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 4, characterized in that, In step one, the nanoporous metal heterostructure is selected from one of the following combinations: Ti / Ni heterojunction, Ti:Ni atomic ratio 1:0.5-1:2; Ti / Fe heterojunction, Ti:Fe atomic ratio 1:0.5-1:2; V / Ni heterojunction, V:Ni atomic ratio 1:0.5-1:2; Zr / Co heterojunction, Zr:Co atomic ratio 1:0.5-1:2; Ti / Ni / Fe ternary heterostructure, with Ti:Ni:Fe atomic ratio of 1:0.5-2:0.5-2.
6. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, In step one, the electrolyte solution is an alkaline electrolyte or an acidic electrolyte; The concentration of the electrolyte solution is 0.1-5 M; The alkaline electrolyte is a NaOH solution or a KOH solution; the acidic electrolyte is a H2SO4 solution or an HCl solution. The process parameters for the electrochemical selective dissolution are: electrode voltage 0.5-5 V, polarization time 10-120 minutes, and electrolysis temperature 20-80℃. The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃. The washing process involves alternating between deionized water and anhydrous ethanol for 3-5 times. The drying process is vacuum drying, at a temperature of 40-80℃, for 2-6 hours.
7. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, In step two, the solid-liquid ratio of the nanoporous metal heterostructure to the dibutylmagnesium solution is 1:5-1:20 (g:mL). The concentration of the dibutylmagnesium solution is 0.5-1.5 M, and its solvent is heptane or hexane; The frequency of the first frequency ultrasound is 20-40 kHz; the power of the first frequency ultrasound is 100-300 W; the processing temperature of the first frequency ultrasound is 0-25℃; and the processing time of the first frequency ultrasound is 30-120 minutes. The soaking time is 2-6 hours.
8. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, In step three, the purity of the high-purity hydrogen gas is ≥99.999%; The initial hydrogen pressure is 1-3 MPa; The frequency of the second frequency ultrasound is 60-100 kHz; the power of the second frequency ultrasound is 50-200 W. The programmed heating method is as follows: heat up to the first temperature range of 80-120℃ at a rate of 1-5℃ / min, hold for 30-60 minutes; then continue to heat up to the second temperature range of 150-200℃ at a rate of 1-5℃ / min, hold for 60-120 minutes. The dynamic pressure control is as follows: when the temperature rises to the second temperature range, the hydrogen pressure is simultaneously adjusted from the initial pressure to 3-8 MPa; the dynamic pressure control is a linear pressurization mode with a pressurization rate of 0.05-0.1 MPa / min.
9. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, In step four, the organic solvent is anhydrous heptane or hexane; The vacuum drying conditions are 40-60℃ for 2-4 hours; The mechanical peeling method is slight abrasion or airflow purging.
10. The method for preparing a nanoporous heterojunction-supported magnesium hydride composite hydrogen storage material synthesized by electrolysis-assisted ultrasonic impregnation according to claim 3, characterized in that, An insertion-type ultrasonic probe is installed inside the high-pressure reactor; both the first and second frequency ultrasonic probes adopt pulse mode with a duty cycle of 30-70%. In step two, repeat the "ultrasonic-assisted impregnation-static soaking" cycle 2-3 times, and dry to remove the solvent after each cycle; The electrochemical selective dissolution employs a three-electrode system, with AB alloy as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode; the electrolysis voltage is 1-3 V, the electrolysis time is 30-90 minutes, and the electrolysis temperature is 30-60℃.