A method for preparing sodium intercalation-induced high-purity 1T phase molybdenum disulfide solid-state hydrogen storage material

Abstract

A method for preparing a sodium intercalation-induced high-purity 1T-phase molybdenum disulfide solid-state hydrogen storage material comprises: adding ammonium molybdate, ammonium thioacetyl, and urea to deionized water and stirring uniformly to obtain a precursor solution; subjecting the precursor solution to a hydrothermal reaction and then rapidly cooling to room temperature to obtain a crude product solution; refrigerating the crude product solution at 4°C for insulation, centrifuging, and washing to retain a solid MoS2 primary product; adding deionized water and ultrasonically treating to obtain a MoS2 deionized water dispersion; adding Na2SO4 to the MoS2 deionized water dispersion, stirring thoroughly with a magnetic stirrer, and then centrifuging, washing, ultrasonically treating, and drying in a vacuum oven to obtain the product. Advantageously, the material combines the high hydrogen storage density of chemical adsorption-type hydrogen storage materials with the good kinetic properties of physical adsorption-type hydrogen storage materials, resulting in a high hydrogen storage density, fast hydrogen absorption and desorption rates, and mild operating conditions.

Description

Technical Field

[0001] The invention relates to a preparation method of a sodium intercalation-induced high-purity 1T-phase molybdenum disulfide solid-state hydrogen storage material, which is mainly used for solid-state hydrogen storage materials. Technical Background

[0002] As a highly anticipated clean energy source, hydrogen energy has attracted much attention due to its unique advantages, including a high calorific value of 142 megajoules per kilogram, widely distributed resources, non-toxicity, and environmental friendliness, making it one of the first choices to replace traditional fossil fuels in the future. However, a major difficulty in the application of hydrogen energy lies in the efficient storage of hydrogen. Hydrogen energy storage is divided into three-state energy storage methods: solid, liquid, and gas. Traditional high-pressure gaseous and low-temperature liquid hydrogen storage methods have poor safety and high costs, which are not conducive to the storage and transportation of hydrogen. Solid-state hydrogen storage technology stands out from solid, liquid, and gas energy storage methods due to its high mass hydrogen storage density and volume hydrogen storage density as well as safety in practical applications.

[0003] The development of solid-state hydrogen storage materials is still in its early stages and is primarily divided into two types: intercalation-type hydrogen storage materials, represented by MgH2, AlH3, and LiBH4, whose hydrogen storage mechanism primarily relies on chemical reactions of cracked hydrogen molecules. Physical adsorption-type hydrogen storage materials, represented by graphene, porous carbon, and carbon nanotubes, primarily rely on physical adsorption of undisturbed hydrogen molecules. Intercalation-type hydrogen storage materials exhibit slow kinetics, poor cyclic stability, and demanding operating conditions during hydrogen absorption and desorption due to the high energy barrier for hydrogen molecules to dissociate on the surface of the host material and their strong chemical bonding with hydrogen atoms. While physical adsorption-type hydrogen storage materials offer good cyclic stability and fast hydrogen absorption and desorption kinetics, their weak van der Waals interactions with hydrogen molecules result in relatively low hydrogen storage density at ambient pressure. CN112960696 B discloses "a wide interlayer spacing molybdenum disulfide nanosheet and its preparation method." The molybdenum disulfide nanosheets have an interlayer spacing of 0.95 nm and a thickness of 5 to 10 nm. MoS2 belongs to TMDs (transition metal sulfides), which itself has a graphene-like hierarchical structure, and the layers are connected by weak van der Waals forces. It has three phases: 2H, 1T, and 3R, of which 2H is a stable structure, and 1T and 3R are metastable structures. The material itself has rich structural characteristics and special functional properties, a large specific surface area, and is easy to prepare nanoscale samples. Due to the presence of S atoms and Mo atoms, it has a large adsorption capacity. At the same time, it is low in price and can be mass-produced. The molybdenum disulfide nanosheets obtained by this method are still dominated by the 2H phase structure, with low hydrogen storage capacity, and are not suitable for use as hydrogen storage materials. As a metastable 1T phase MoS2 structure, it has higher conductivity and hydrophilicity, and its atomic coordination structure is octahedral coordination, which has more surface activity and has a positive effect on the transport of cations, Na+ The diffusion barrier in the 1T phase is lower, and its layered structure composed of weak van der Waals forces can be + The intercalation layer has a larger interlayer spacing, providing more storage sites for H2 molecules to adsorb. However, the 1T phase is metastable and difficult to store in bulk or for long periods of time. In practice, intercalation technology also suffers from problems such as long intercalation times and low 1T phase content. Therefore, there is an urgent need to develop a hydrogen storage material that combines these advantages while offering high hydrogen storage density, fast hydrogen absorption and desorption rates, and mild operating conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a sodium intercalation-induced high-purity 1T phase molybdenum disulfide solid-state hydrogen storage material. The material obtained by the preparation method has a high 1T phase ratio. At the same time, the material can simultaneously take into account the dual advantages of high hydrogen storage density of chemical adsorption type hydrogen storage materials and good kinetic properties of physical adsorption type hydrogen storage materials, so that it has the advantages of good hydrogen storage density, fast hydrogen absorption and desorption rate, mild operating conditions, etc.

[0005] The technical solution of the present invention is:

[0006] A method for preparing a sodium intercalation-induced high-purity 1T-phase molybdenum disulfide solid-state hydrogen storage material, the specific steps of which are as follows:

[0007] (1) Preparation of precursor solution

[0008] Ammonium molybdate, ammonium thioacetate, and urea were added to deionized water in a mass ratio of 5:6:20 and stirred thoroughly with a magnetic stirrer to obtain a precursor solution;

[0009] (2) Hydrothermal reaction

[0010] The precursor solution is transferred to a hydrothermal synthesis reactor, subjected to hydrothermal reaction at 180°C-220°C for 18h-24h, and then rapidly cooled to room temperature to obtain a crude product solution;

[0011] (3) Preparation of MoS2 primary product

[0012] The crude product solution was placed in a refrigerator at 4°C for 2 hours, centrifuged at a speed of 8000 rpm-9000 rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol to retain the solid MoS2 primary product; deionized water was added according to a mass ratio of 1:5 between the solid MoS2 primary product and deionized water, and the product was ultrasonically treated for 30 minutes to 60 minutes to obtain a MoS2 deionized water dispersion;

[0013] (4) Preparation of Na intercalation-induced high-purity 1T phase solid-state hydrogen storage materials

[0014] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 initial product of 2:1, and the mixture was fully stirred with a magnetic stirrer. After mixing evenly, the mixture was centrifuged at a speed of 8000rpm-9000rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol. After washing, the solid material was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment. Subsequently, the product was dried in an oven at 60℃-100℃ under vacuum for 4h-6h to obtain a powdery gray-black Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material.

[0015] Furthermore, in step (4), the stirring speed is 100 rpm-130 rpm, and the stirring time is 0.5 h-1 h.

[0016] Furthermore, rapid cooling is achieved by immersing in cold water, pouring with continuous water flow, or placing in a low temperature environment.

[0017] Furthermore, in step (1), the stirring speed is 300 rpm-450 rpm, and the stirring time is 0.5 h-2 h.

[0018] Furthermore, the amount of deionized water added in step (1) accounts for 1 / 3-2 / 3 of the volume of the hydrothermal synthesis reactor.

[0019] As a further preference, the mass ratio of the total mass of ammonium molybdate, ammonium thioacetate and urea to deionized water in step (1) is 6.5:1000.

[0020] Furthermore, the deionized water and anhydrous ethanol were washed alternately three times.

[0021] Beneficial effects of the present invention:

[0022] (1) The process is simple and reasonable, using ammonium molybdate ((NH4)6Mo7O 24 4H2O) is a Mo precursor, thioacetyl ammonium (C2H5NS) is a S precursor, urea CH4N2O acts as a regulator to adjust the reaction conditions, and as a reducing agent and gelling agent to assist in the preparation. In this system, the addition of metal salts at a later stage can help form relatively uniform grains in the metal nanocrystals. By controlling the urea concentration and reaction conditions, metal nanoparticles of suitable size and shape can be prepared. The addition of deionized water can not only act as a dissolving medium for drugs such as precursors, but also help eliminate the influence of other ionic impurities on the final product. After the hydrothermal reaction, refrigeration at 4°C can fully precipitate and separate the hydrothermal products, making the products more stable. + The intercalated 1T-MoS2 makes Na2SO4 fully dissolved in the solution, Na +It can be intercalated into 1T-MoS2, increasing the interlayer spacing of 1T-MoS2 products, and the acid ions it carries will play a role in the subsequent hydrogen storage performance. Compared with commercial MoS2, it has a larger hydrogen storage space. Secondly, the introduction of Na + During intercalation, it provides co-donating sites for chemical adsorption, ultimately making the homemade intercalated MoS2 have the characteristics of both physical adsorption and chemical adsorption. Compared with unintercalated MoS2 and commercial MoS2, its hydrogen storage capacity and cyclic stability show opposite hydrogen storage characteristics. Its hydrogen storage capacity increases with increasing pressure, number of cycles, and temperature, rather than continuously decreasing as before.

[0023] (2) The prepared Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material has coexistence of 1T phase and 2H phase, with the 1T phase being dominant, accounting for up to 74%. At the same time, the interlayer spacing increases accordingly, providing more space for hydrogen adsorption. Compared with commercial nano-MoS2, the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material of the present invention has a few-layer structure, is not easy to cluster, and has better hydrogen storage capacity and cyclic stability;

[0024] (3) The prepared Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material is a non-cracking chemical adsorption hydrogen storage material. Its surface induces chemical adsorption and has a medium adsorption strength between physical adsorption and chemical reaction. The material can simultaneously take into account the dual advantages of high hydrogen storage density of chemical adsorption type hydrogen storage materials and good kinetic properties of physical adsorption type hydrogen storage materials. It has good hydrogen storage density, fast hydrogen absorption and desorption rate, and mild operating conditions.

[0025] (a) Compared with existing physical adsorption materials, such as activated carbon and graphene, it has a wider range of applicable conditions. Its hydrogen release capacity is tested using the same brute force test method as chemical adsorption, that is, a vacuum pump is used to extract the hydrogen from the material and the space in which the material is located, reducing the pressure to 0.001 bar, and then the temperature is raised to release the hydrogen. If the same test method is used on activated carbon / graphene materials, the stored hydrogen will be completely released when the vacuum is evacuated or even when the pressure value returns to normal pressure (1 bar). In terms of hydrogen absorption, it directly uses room temperature instead of liquid nitrogen, which already meets the international hydrogen storage target of storing hydrogen at room temperature.

[0026] (b) The prepared Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material has a lower first hydrogen release temperature than existing physical adsorption materials and existing chemical adsorption materials, such as LiBH4 and MgH2. It can release a small amount of hydrogen at room temperature and most of its stored hydrogen in the range of 50°C to 80°C, with an even lower hydrogen release temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A scanning electron microscope photograph of the Na intercalation-induced high-purity 1T phase solid hydrogen storage material prepared in the present invention (corresponding to Example 1) at 10 μm and an energy spectrum diagram of the corresponding elements;

[0028] Figure 2 Scanning electron microscope photos of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1) at different scales;

[0029] Figure 3 Transmission electron micrographs of the Na intercalation-induced high-purity 1T-phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1) at different scales;

[0030] Figure 4 High-resolution transmission microscopy photographs and interlayer spacing measurements of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0031] Figure 5 This is the energy spectrum of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0032] Figure 6 This is the full X-ray photoelectron spectrum of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0033] Figure 7 This is a high-resolution X-ray photoelectron spectrum of Na 1s orbitals of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0034] Figure 8 A high-resolution X-ray photoelectron spectrum of the C1s orbital in the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0035] Figure 9 This is a high-resolution X-ray photoelectron spectrum of Mo 3d orbitals in the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0036] Figure 10 A high-resolution X-ray photoelectron spectrum of the S2p orbitals in the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0037] Figure 11 This is an X-ray characterization image of the Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1);

[0038] Figure 12The hydrogen adsorption curves of the unintercalated primary molybdenum disulfide hydrogen storage material (hydrogen partial pressures are 3 MPa, 4 MPa, and 5 MPa respectively);

[0039] Figure 13 The hydrogen adsorption curves (hydrogen partial pressures of 3 MPa, 4 MPa, and 5 MPa, respectively) of the Na intercalation-induced high-purity 1T-phase solid-state hydrogen storage material prepared in the present invention (corresponding to Example 1) are shown;

[0040] Figure 14 This is the hydrogen desorption curve of the currently commercially available nano-scale molybdenum disulfide hydrogen storage material under different conditions, which are as follows: adsorption (hydrogen partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen partial pressure 5 MPa) followed by desorption (heating to 500°C), a hydrogen desorption curve for three cycles;

[0041] Figure 15 The hydrogen desorption curves of the unintercalated primary molybdenum disulfide hydrogen storage material under different conditions are as follows: adsorption (hydrogen partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen partial pressure 5 MPa) followed by desorption (heating to 500°C), three cycles of hydrogen desorption curves; Figure 16 The hydrogen desorption curves of the Na intercalation-induced high-purity 1T phase solid hydrogen storage material prepared according to the present invention (corresponding to Example 1) under different conditions are as follows: adsorption (hydrogen absorption partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen absorption partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen absorption partial pressure 5 MPa) followed by desorption (heating to 500°C), a hydrogen desorption curve for three cycles;

[0042] Figure 17 The hydrogen desorption curves of the Na intercalation solid hydrogen storage material prepared in the present invention (corresponding to Example 1) under different conditions are as follows: adsorption (hydrogen absorption partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen absorption partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen absorption partial pressure 5 MPa) followed by desorption (heating to 500°C), a hydrogen desorption curve of three cycles;

[0043] Figure 18 The hydrogen desorption curves of the Na intercalation solid hydrogen storage material prepared according to the present invention (corresponding to Example 2) under different conditions are continuously performed, namely: adsorption (hydrogen absorption partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen absorption partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen absorption partial pressure 5 MPa) followed by desorption (heating to 500°C), a hydrogen desorption curve of three cycles. DETAILED DESCRIPTION

[0044] Example 1

[0045] (1) Preparation of precursor solution

[0046] 75 mg of ammonium molybdate, 90 mg of ammonium thioacetate, and 300 mg of urea were added to 70 mL of deionized water and stirred at 450 rpm with a magnetic stirrer for 30 minutes to obtain a precursor solution;

[0047] (2) Hydrothermal reaction

[0048] The precursor solution was transferred to a 100 mL hydrothermal synthesis reactor and subjected to hydrothermal reaction at 180°C for 18 h. The hydrothermal synthesis reactor was then immersed in cold water and rapidly cooled to room temperature to obtain a crude product solution.

[0049] (3) Preparation of MoS2 primary product

[0050] The crude product solution was placed in a refrigerator at 4°C for 2 h, centrifuged at 9000 rpm for 30 min, and the product was washed alternately with deionized water and anhydrous ethanol three times to retain the solid MoS2 primary product; deionized water was added according to the mass ratio of the solid MoS2 primary product to deionized water of 1:5, and the product was ultrasonically treated for 30 min to obtain a MoS2 deionized water dispersion; (4) Preparation of Na intercalation-induced high-purity 1T phase solid hydrogen storage material

[0051] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 of 2:1, and stirred at 120 rpm with a magnetic stirrer for 30 minutes. After mixing evenly, the mixture was centrifuged at 9000 rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol for 3 times. After washing, the solid material was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment, and then dried at 70°C in a vacuum oven for 6 hours to obtain a powdery gray-black Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material.

[0052] The scanning electron microscope photograph of the Na intercalation-induced high-purity 1T phase solid hydrogen storage material of this embodiment at 10 μm and the energy spectrum of its corresponding elements are shown in Figure 1. Figure 1 The scanning electron microscope in the figure shows its surface morphology and the characteristics of Na crystals; its energy spectrum clearly shows that the elements C, Na, S, and Mo exist and are evenly distributed.

[0053] The scanning electron microscope photos of the Na intercalation-induced high-purity 1T phase solid hydrogen storage material at different scales are shown in Figure 2. Figure 2 As shown by Figure 2(b) clearly shows the morphology of the sample. The layered characteristics of MoS2 can be observed. At the same time, Na exists on the surface of MoS2. While intercalating MoS2 to ensure the expansion of the interlayer spacing, it can also play some of its own characteristics, such as Figure 2 (ej) proves that the preparation method of this embodiment not only improves the hydrogen storage performance by expanding the interlayer spacing of molybdenum disulfide, but also retains the intrinsic advantages of Na2SO4 and provides sites for chemical adsorption.

[0054] The transmission electron microscopy images of the high-purity 1T phase solid hydrogen storage material induced by Na intercalation in this embodiment at different scales are shown in Figure 2. Figure 3 As shown in the high-resolution transmission microscopy images and the interlayer spacing measurements, Figure 4 As shown, the energy spectrum is as Figure 5 As shown;

[0055] Figure 3 This further proves that the preparation method retains the morphological characteristics of molybdenum disulfide; Figure 4 This further supports the expansion of the interlayer spacing of MoS2; Figure 5 It also further proves the introduction of Na element and its uniform distribution.

[0056] The full spectrum of X-ray photoelectron spectrum of Na intercalation-induced high-purity 1T phase solid hydrogen storage material in this embodiment is shown in the figure below. Figure 6 As shown; Na 1s orbital high resolution X-ray photoelectron spectrum is shown Figure 7 As shown; the high-resolution X-ray photoelectron spectrum of C 1s orbital is shown Figure 8 As shown; the high-resolution X-ray photoelectron spectrum of Mo 3d orbital is shown Figure 9 As shown; the high-resolution X-ray photoelectron spectrum of S2p orbital is shown Figure 10 As shown; Figure 6 This further supports the above-mentioned energy spectrum characterization results. Figure 7 , which proves the successful introduction of Na element into the sample, which can be verified by the above SEM, EDS, and HAADF Mapping images. Figure 8 Energy spectrum analysis of element C, Figure 9 The high-resolution X-ray photoelectron spectroscopy of the Mo 3d orbital proves the existence of the 1T phase, and the 1T phase content is relatively high. After calculation through the peak area ratio, it is concluded that the relative content of the 1T phase is as high as 74%, among which there is a partial oxidation state. This indicates that partial oxidation may bring better hydrogen storage performance. Its less sensitive property to oxidation makes it easier to move towards industrialization. Figure 10 The energy spectrum of the S2p orbital also proves the coexistence of the 1T phase and the 2H phase, with the 1T phase dominating. It also proves the existence of Na2SO4, providing evidence for its chemical adsorption. In summary, the success of this preparation method is proven.

[0057] The X-ray characterization of the Na intercalation-induced high-purity 1T phase solid hydrogen storage material of this embodiment is shown in FIG. Figure 11 As shown; Figure 11 It can be clearly seen that it retains the presence of some MoS2 and some Na2SO4, and the characteristic peaks of the two appear at the same time, working synergistically to improve hydrogen storage performance.

[0058] The hydrogen adsorption curve of the high-purity 1T phase solid hydrogen storage material induced by Na intercalation in this embodiment is as follows Figure 13 shown; with Figure 12 The unintercalated primary molybdenum disulfide hydrogen storage material (the MoS2 deionized water dispersion prepared in this embodiment is directly dried in an oven at 70°C under vacuum for 6 hours) has obvious physical adsorption properties, such as Figure 13 The material also demonstrated its physical adsorption properties, with the higher the pressure, the greater the hydrogen absorption. It also exhibited extremely high hydrogen storage capacities (8.1% and 7.3%) and rapid kinetics, reaching saturation within seconds.

[0059] Hydrogen desorption test:

[0060] The hydrogen desorption of purchased commercial nano-scale molybdenum disulfide, the unintercalated primary molybdenum disulfide hydrogen storage material (the MoS2 deionized water dispersion prepared in this example was directly dried in an oven at 70°C under vacuum for 6 hours), and the Na intercalation-induced high-purity 1T phase solid hydrogen storage material of this example were tested using the same conditions, specifically:

[0061] Each sample was subjected to three sets of hydrogen absorption and desorption tests at once, which were hydrogen absorption at 3MPa, heating and desorption (180℃), hydrogen absorption at 4MPa, heating and desorption (300℃), and hydrogen absorption at 5MPa, heating and desorption (500℃). That is, each sample was subjected to three sets of hydrogen absorption and desorption tests. The hydrogen desorption curve is shown in the figure below. Figure 14 、 15 16, which are respectively the hydrogen desorption curves of commercial nano-scale molybdenum disulfide, the hydrogen desorption curve of the unintercalated primary molybdenum disulfide hydrogen storage material, and the hydrogen desorption curve of the Na ion intercalated molybdenum disulfide hydrogen storage material prepared in this embodiment.

[0062] in, Figure 14 and Figure 15 All of them showed poor cycle performance and low hydrogen release, and the hydrogen release gradually decreased with the number of cycles (the hydrogen release of traditional activated carbon is almost 0 at this temperature); the unintercalated primary molybdenum disulfide hydrogen storage material showed better desorption performance due to the presence of a small amount of 1T phase in it, but the cycle stability showed the same trend as commercial MoS2. Figure 16The hydrogen absorption and desorption curves of the sample are exactly the opposite. Although the initial desorption rate is low, it reaches a hydrogen desorption rate of 2.2% as the cycle progresses. This demonstrates the uniqueness of this sample and its combination of chemical and physical adsorption. It can still release more hydrogen during the continuous heating process, indicating the presence of chemical adsorption. The hydrogen release rate also increases with increasing pressure, demonstrating its physical adsorption capacity. The test method does not use PCT testing. Instead, similar to traditional chemical adsorption materials, the easily released hydrogen is extracted before testing. This is potential evidence that the adsorption rate is far greater than the release rate. Figure 16 As shown, the sufficiently high hydrogen release capacity and special cycling characteristics demonstrate the successful preparation of this hydrogen storage material.

[0063] Comparative Example 1 only changes the mass ratio of Na2SO4 to MoS2 to 1:2, and the rest is the same as Example 1

[0064] (1) Preparation of precursor solution

[0065] 75 mg of ammonium molybdate, 90 mg of ammonium thioacetate, and 300 mg of urea were added to 70 mL of deionized water and stirred at 450 rpm with a magnetic stirrer for 30 minutes to obtain a precursor solution;

[0066] (2) Hydrothermal reaction

[0067] The precursor solution was transferred to a 100 mL hydrothermal synthesis reactor and subjected to hydrothermal reaction at 180°C for 18 h. The hydrothermal synthesis reactor was then immersed in cold water and rapidly cooled to room temperature to obtain a crude product solution.

[0068] (3) Preparation of MoS2 primary product

[0069] The crude product solution was placed in a refrigerator at 4°C for 2 hours, centrifuged at 9000 rpm for 30 minutes, and washed with deionized water and anhydrous ethanol three times to retain the solid MoS2 primary product; deionized water was added according to the mass ratio of the solid MoS2 primary product to deionized water of 1:5, and ultrasonically treated for 30 minutes to obtain a MoS2 deionized water dispersion; (4) Preparation of Na intercalation solid hydrogen storage material

[0070] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 of 1:2, and stirred at 120 rpm with a magnetic stirrer for 30 minutes. After mixing evenly, the mixture was centrifuged at 9000 rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol for 3 times. After washing, the solid matter was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment, and then dried in an oven at 70°C under vacuum for 6 hours to obtain a powdery gray-black Na intercalation solid hydrogen storage material.

[0071] The hydrogen desorption curves of the Na intercalation solid hydrogen storage material prepared in Comparative Example 1 were continuously subjected to different conditions, which were: adsorption (hydrogen partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen partial pressure 5 MPa) followed by desorption (heating to 500°C). The hydrogen desorption curves of the three cycles were as follows: Figure 17 shown by Figure 17 and Figure 15 By comparison, it can be seen that Figure 17 In the first desorption, the desorption capacity is enhanced due to the presence of intercalation, but the overall cycle stability is Figure 15 The prepared unintercalated primary molybdenum disulfide hydrogen storage material is similar. Compared with Example 1, Comparative Example 1 still has no breakthrough in cycle stability, and the hydrogen storage performance is not ideal.

[0072] Comparative Example 2 only changes the mass ratio of Na2SO4 to MoS2 to 1:1, and the rest is the same as Example 1

[0073] (1) Preparation of precursor solution

[0074] 75 mg of ammonium molybdate, 90 mg of ammonium thioacetate, and 300 mg of urea were added to 70 mL of deionized water and stirred at 450 rpm with a magnetic stirrer for 30 minutes to obtain a precursor solution;

[0075] (2) Hydrothermal reaction

[0076] The precursor solution was transferred to a 100 mL hydrothermal synthesis reactor and subjected to hydrothermal reaction at 180°C for 18 h. The hydrothermal synthesis reactor was then immersed in cold water and rapidly cooled to room temperature to obtain a crude product solution.

[0077] (3) Preparation of MoS2 primary product

[0078] The crude product solution was placed in a refrigerator at 4°C for 2 hours, centrifuged at 9000 rpm for 30 minutes, and washed with deionized water and anhydrous ethanol three times to retain the solid MoS2 primary product; deionized water was added according to the mass ratio of the solid MoS2 primary product to deionized water of 1:5, and ultrasonically treated for 30 minutes to obtain a MoS2 deionized water dispersion; (4) Preparation of Na intercalation solid hydrogen storage material

[0079] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 of 1:1, stirred at 120 rpm with a magnetic stirrer for 30 minutes, and after mixing evenly, dried in an oven at 70°C under vacuum for 6 hours to obtain a powdery gray-black Na intercalation solid hydrogen storage material.

[0080] Figure 18 The hydrogen desorption curves of the Na intercalation solid hydrogen storage material prepared in Comparative Example 2 of the present invention under different conditions are continuously subjected to the following steps: adsorption (hydrogen absorption partial pressure 3 MPa) followed by desorption (heating to 180°C) - adsorption (hydrogen absorption partial pressure 4 MPa) followed by desorption (heating to 300°C) - adsorption (hydrogen absorption partial pressure 5 MPa) followed by desorption (heating to 500°C). The hydrogen desorption curves of the three cycles are shown in FIG. Figure 18 As shown; Figure 18 Relative to Figure 16 Come and see, Figure 18 The maximum hydrogen storage capacity is low, and in the third cycle, Figure 16 The same trend, although it has improved, but it cannot reach Figure 16 The hydrogen storage capacity is shown.

[0081] Example 2

[0082] (1) Preparation of precursor solution

[0083] 75 mg of ammonium molybdate, 90 mg of ammonium thioacetate, and 300 mg of urea were added to 70 mL of deionized water and stirred at 300 rpm with a magnetic stirrer for 120 minutes to obtain a precursor solution;

[0084] (2) Hydrothermal reaction

[0085] The precursor solution was transferred to a 100 mL hydrothermal synthesis reactor and subjected to hydrothermal reaction at 200 °C for 24 h. The hydrothermal synthesis reactor was then immersed in cold water and rapidly cooled to room temperature to obtain a crude product solution.

[0086] (3) Preparation of MoS2 primary product

[0087] The crude product solution was placed in a refrigerator at 4°C for 2 h, centrifuged at 8000 rpm for 30 min, and the product was washed alternately with deionized water and anhydrous ethanol three times to retain the solid MoS2 primary product; deionized water was added according to the mass ratio of the solid MoS2 primary product to deionized water of 1:5, and the product was ultrasonically treated for 60 min to obtain a MoS2 deionized water dispersion; (4) Preparation of Na intercalation-induced high-purity 1T phase solid hydrogen storage material

[0088] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 of 2:1, and stirred at 100 rpm with a magnetic stirrer for 45 minutes. After mixing evenly, the mixture was centrifuged at 8000 rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol for 3 times. After washing, the solid material was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment, and then dried at 60°C in a vacuum oven for 5 hours to obtain a powdery gray-black Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material.

[0089] Example 3

[0090] (1) Preparation of precursor solution

[0091] 75 mg of ammonium molybdate, 90 mg of ammonium thioacetate, and 300 mg of urea were added to 70 mL of deionized water and stirred at 350 rpm with a magnetic stirrer for 60 minutes to obtain a precursor solution;

[0092] (2) Hydrothermal reaction

[0093] The precursor solution was transferred to a 100 mL hydrothermal synthesis reactor and subjected to hydrothermal reaction at 220°C for 20 h. The hydrothermal synthesis reactor was then immersed in cold water and rapidly cooled to room temperature to obtain a crude product solution.

[0094] (3) Preparation of MoS2 primary product

[0095] The crude product solution was placed in a refrigerator at 4°C for 2 h, centrifuged at 8500 rpm for 30 min, and washed alternately with deionized water and anhydrous ethanol for 3 times to retain the solid MoS2 primary product; deionized water was added according to the mass ratio of the solid MoS2 primary product to deionized water of 1:5, and ultrasonically treated for 45 min to obtain a MoS2 deionized water dispersion; (4) Preparation of Na intercalation-induced high-purity 1T phase solid hydrogen storage material

[0096] Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 of 2:1, and stirred at 130 rpm with a magnetic stirrer for 60 minutes. After mixing evenly, the mixture was centrifuged at 8500 rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol for 3 times. After washing, the solid material was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment, and then dried at 100°C in a vacuum oven for 4 hours to obtain a powdery gray-black Na intercalation-induced high-purity 1T phase solid-state hydrogen storage material.

[0097] The above are merely specific embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material, characterized by: (1) Preparation of precursor solution Ammonium molybdate, ammonium thioacetate, and urea were added to deionized water in a mass ratio of 5:6:20 and stirred thoroughly with a magnetic stirrer to obtain a precursor solution; (2) Hydrothermal reaction The precursor solution is transferred to a hydrothermal synthesis reactor, subjected to hydrothermal reaction at 180°C-220°C for 18h-24h, and then rapidly cooled to room temperature to obtain a crude product solution; (3) Preparation of MoS2 primary product The crude product solution was refrigerated and kept warm at 4°C for 2 hours, centrifuged at a speed of 8000-9000 rpm for 30 minutes, and the product was washed alternately with deionized water and ethanol to retain the solid MoS2 primary product; deionized water was added according to a mass ratio of 1:5 between the solid MoS2 primary product and deionized water, and the product was ultrasonically treated for 30-60 minutes to obtain a MoS2 deionized water dispersion; (4) Preparation of Na ion intercalation-induced 1T phase MoS2 solid-state hydrogen storage material Na2SO4 was added to the MoS2 deionized water dispersion according to the mass ratio of Na2SO4 to MoS2 initial product of 2:1, and the mixture was fully stirred with a magnetic stirrer. After mixing evenly, the mixture was centrifuged at a speed of 8000rpm-9000rpm for 30 minutes, and the product was washed alternately with deionized water and anhydrous ethanol. After washing, the solid material was retained and deionized water was added at a ratio of 1:5 for ultrasonic treatment. Subsequently, the product was dried in an oven at 60℃-100℃ under vacuum for 4h-6h to obtain a powdery gray-black Na ion intercalation induced 1T phase molybdenum disulfide solid hydrogen storage material.

2. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 1, characterized in that: In step (4), the stirring speed is 100 rpm-130 rpm, and the stirring time is 0.5 h-1 h.

3. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 1, characterized in that: Rapid cooling is achieved by immersing in cold water, pouring water continuously or placing in a low temperature environment.

4. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 1, characterized in that: In step (1), the stirring speed is 300 rpm-450 rpm, and the stirring time is 0.5 h-2 h.

5. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 1, characterized in that: The amount of deionized water added in step (1) accounts for 1 / 3-2 / 3 of the volume of the hydrothermal synthesis reactor.

6. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 5, characterized in that: In step (1), the mass ratio of the total mass of ammonium molybdate, ammonium thioacetate and urea to deionized water is 6.5:1000.

7. The method for preparing the sodium intercalation-induced 1T phase molybdenum disulfide solid hydrogen storage material according to claim 1, characterized in that: In step (3) and step (4), the washing times of deionized water and ethanol are alternating 3 times.

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