Nickel or nickel oxide supported ceria doped lithium aluminum hydride hydrogen storage material and method of making

Abstract

This invention discloses a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, prepared by mechanical ball milling of a supported sample and lithium aluminum hydride. The supported sample is obtained by calcining a precipitate formed by mixing nickel nitrate as the nickel source and cerium nitrate as the cerium source with sodium hydroxide solution in a certain weight ratio and heating. The supported sample is either nickel-supported cerium dioxide or nickel oxide-supported cerium dioxide, named Ni@CeO2 and NiO@CeO2, respectively. The preparation method includes: step 1) preparation of nickel or nickel oxide-supported cerium dioxide; step 2) preparation of the nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material. For application in the field of hydrogen storage, the final system's hydrogen release temperature is reduced to 63.9 to 93.5℃, the hydrogen release amount reaches 6.7 to 7.1 wt%, and the hydrogen release rate is 88.94 to 96.03%. This invention achieves improved hydrogen storage material performance at lower temperatures.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage materials technology in new energy materials, and relates to, but is not limited to, nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials and their preparation methods. Background Technology

[0002] The excessive consumption of fossil fuels globally has resulted in the emission of large amounts of greenhouse gases (CO2), causing the global greenhouse effect and environmental pollution. To address energy consumption issues, many countries have begun developing and utilizing various renewable energy sources. Among them, hydrogen fuel has advantages such as renewable recycling, zero emissions, and high energy density, making it one of the important resources for global development and utilization.

[0003] Among aluminum-based hydrogen storage materials, lithium aluminum hydride (LHH) possesses advantages such as high hydrogen storage capacity (10.6 wt%) and environmental friendliness, making it one of the most promising solid-state hydrogen storage materials. However, in practical applications, it suffers from poor reversibility and slow desorption kinetics. Common solutions include catalytic doping, nano-sizing, and multiphase composites to improve hydrogen storage performance, achieving good results.

[0004] Catalytic doping can effectively address the problem of slow desorption kinetics. Among catalytic doping methods, transition metals, as catalysts, have a significant effect on improving the dehydrogenation performance of LiAlH4. One related technique describes the catalytic performance of three different morphologies of cerium dioxide-doped LiAlH4, achieving improved dehydrogenation performance and lowering the activation energy of the reaction. However, air drying may contaminate the sample, insufficient sample purity can affect the reaction effect, and excessively long temperature and time are also issues. Another technique investigated the effect of different CeO2 doping amounts on the performance improvement of LiAlH4. SEM analysis revealed changes in sample particle size, but the initial dehydrogenation temperature remained high, and the hydrogen release was low, which falls far short of the required hydrogen release performance. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material and its preparation method, which can achieve good hydrogen release at a low initial dehydrogenation temperature and can effectively prepare a catalyst material with high catalytic activity.

[0006] The technical solution of this invention is implemented as follows:

[0007] In a first aspect, embodiments of the present invention provide a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, which is prepared by mechanical ball milling of a supported sample and lithium aluminum hydride; the supported sample is prepared by calcining a precipitate generated by mixing nickel nitrate as a nickel source and cerium nitrate as a cerium source with sodium hydroxide solution in a certain weight ratio and heating the mixture; the supported sample is nickel-supported cerium dioxide or nickel oxide-supported cerium dioxide, respectively named Ni@CeO2 and NiO@CeO2.

[0008] Furthermore, Ni@CeO2 is prepared by calcining a precipitate formed by reacting cerium nitrate and nickel nitrate with sodium hydroxide in a weight ratio of 1:0.1; NiO@CeO2 is prepared by calcining a precipitate formed by reacting cerium nitrate and nickel nitrate with sodium hydroxide in a weight ratio of 1:0.3.

[0009] Furthermore, the microstructure of cerium dioxide is nanorod-shaped, while the microstructure of Ni@CeO2 and NiO@CeO2 is nanorod-supported small particles. The doping amount of Ni@CeO2 is 7wt%, and the doping amount of NiO@CeO2 is 1wt% to 10wt%.

[0010] Secondly, embodiments of the present invention provide a method for preparing a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, comprising:

[0011] Step 1) Preparation of nickel or nickel oxide-supported cerium dioxide: Nickel nitrate and cerium nitrate are mixed in a certain weight ratio and dissolved in deionized water. The mixture is then hydrothermally reacted with sodium hydroxide solution in a reactor. The precipitate generated by the reaction is washed and dried under certain conditions. The resulting sample is then calcined under certain conditions to obtain nickel or nickel oxide-supported cerium dioxide materials, which are named Ni@CeO2 and NiO@CeO2, respectively.

[0012] Step 2) Preparation of nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials: Using Ni@CeO2 or NiO@CeO2 obtained in Step 1 as a catalyst, and mechanically ball-milling with lithium aluminum hydride under certain conditions with a certain doping amount, nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials can be obtained, named LiAlH4 / Ni@CeO2 and LiAlH4 / NiO@CeO2, respectively.

[0013] Furthermore, when the weight ratio of the mixed cerium nitrate and nickel nitrate is 1:0.1, the product obtained is Ni@CeO2; when the weight ratio of the mixed cerium nitrate and nickel nitrate is 1:0.3, the product obtained is NiO@CeO2.

[0014] Furthermore, in step 1), the conditions for adding the mixed aqueous solution of cerium nitrate and nickel nitrate to the sodium hydroxide solution are as follows: the stirring speed is 40 to 60 times / minute under magnetic stirring, the stirring time is 20 to 40 minutes, and 1 to 2 ml is added every 2 minutes.

[0015] Further, in step 2), the hydrothermal reaction temperature is 80 to 120°C, and the reaction time is 20 to 25 hours; the filtration and washing conditions are washing the precipitate 3 to 4 times with deionized water; the drying conditions are vacuum drying, drying temperature is 60 to 80°C, and drying time is 10 to 12 hours; the calcination conditions are heating at a rate of 4 to 8°C / minute under air conditions, calcination temperature is 400 to 600°C, and calcination time is 2 to 5 hours.

[0016] Furthermore, in step 2), the NiO@CeO2 doping amount is 1 to 10 wt%; the Ni@CeO2 doping amount is 7 wt%.

[0017] Thirdly, embodiments of the present invention provide a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material for use in the field of hydrogen storage: when the doping amount of Ni@CeO2 as a catalyst is 7wt%, the hydrogen release temperature of the system drops to 81.4℃, and the hydrogen release amount reaches 7wt%; when the doping amount of NiO@CeO2 as a catalyst is 7wt%, the hydrogen release temperature of the system drops to 75.4℃, and the hydrogen release amount reaches 7.1wt%; when the doping amount of NiO@CeO2 as a catalyst is 1-10wt%, the initial hydrogen release temperature drops to 63.9 to 93.4℃, the hydrogen release amount reaches 6.7 to 7.1wt%, and the hydrogen release rate is 88.94 to 96.03%.

[0018] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0019] In this invention embodiment, two different products were obtained by varying the weight ratios of cerium nitrate and nickel nitrate. The prepared Ni and NiO particles can be loaded onto CeO2 nanorods, forming an effective catalyst to improve the hydrogen storage performance of LiAlH4. The method used to prepare the NiO@CeO2 product yields high consistency, as it utilizes uniformly purchased cerium nitrate and nickel nitrate, and the calcination environment is in air to prepare the oxides, resulting in higher sample purity. The hydrogen storage material prepared by this invention can effectively improve the hydrogen desorption performance of lithium aluminum hydride. Attached Figure Description

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

[0021] Figure 1 The XRD patterns of Ni@CeO2 and NiO@CeO2 prepared in Examples 1 and 2 of this invention are shown below.

[0022] Figure 2 SEM image of Ni@CeO2 prepared for specific example 2 of the present invention;

[0023] Figure 3 SEM image of NiO@CeO2 prepared as a specific example 1 of the present invention;

[0024] Figure 4 TEM image of NiO@CeO2 prepared as specific example 1 of the present invention;

[0025] Figure 5 TEM image of Ni@CeO2 prepared as specific example 2 of the present invention;

[0026] Figure 6 The graphs show the dehydrogenation curves of LiAlH4 in specific examples 1, 3, 4 and 5 of the present invention, with no catalyst and with NiO@CeO2 doping amounts of 1wt%, 3wt%, 7wt%, and 10wt%.

[0027] Figure 7 The dehydrogenation curves of LiAlH4, NiO, CeO2 with the same doping ratio and Ni@CeO2 and NiO@CeO2 with the same doping ratio are shown in Specific Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 2 of the present invention.

[0028] Figure 8 Isothermal hydrogen desorption curves of LiAlH4-150, LiAlH4 / NiO@CeO2-90, LiAlH4 / NiO@CeO2-120, LiAlH4 / NiO@CeO2-150, and LiAlH4 / NiO@CeO2-200 in Example 1 and Comparative Example 1 of the present invention;

[0029] Figure 9 The isothermal hydrogen desorption curves of LiAlH4-150, LiAlH4 / Ni@CeO2-150, and LiAlH4 / NiO@CeO2-150 are for Example 1, Comparative Example 1, and Example 2 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. 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.

[0031] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0032] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which these embodiments of the invention pertain. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0033] Related technique one investigated the effect of different CeO2 doping amounts on the performance improvement of LiAlH4. SEM analysis revealed particle size changes in the samples. This technique demonstrated that doped samples exhibited better particle dispersion than undoped samples, while agglomeration resulted in poor dehydrogenation performance. Related technique two achieved an initial hydrogen release temperature of 120℃ and a total hydrogen release of 6.2 wt% by doping LiAlH4 with 3 mol% CeO2. However, this technique suffers from two drawbacks: 1) a relatively high initial dehydrogenation temperature; and 2) a low hydrogen release, which falls far short of the required performance and requires further improvement. Related technique three studied the effect of Ni on the stability of LiAlH4 and its bond interactions using first-principles methods. Ni doping can promote the dehydrogenation of [AlH4]. - The release of H atoms from the group improves the dehydrogenation kinetics of LiAlH4.

[0034] Current research indicates that CeO2 nanorods exhibit a porous, three-dimensional supported structure. Introducing Ni or NiO onto the surface of the CeO2 nanorods allows for the formation of more active sites for CeO2. Nano-CeO2, as a catalyst, can weaken Al-H bonds and accelerate the formation of [AlH4]. - The tetrahedral decomposition of H facilitates the dissociation of H, thereby achieving better hydrogen release performance.

[0035] Based on this theoretical foundation, this invention provides a method to prepare hydrogen storage materials by adjusting the weight ratio of nickel nitrate and cerium nitrate to obtain two different loaded samples, Ni@CeO2 and NiO@CeO2, and doping them with LiAlH4. This method aims to reduce the initial hydrogen release temperature of the hydrogen release process and reduce the amount of catalyst used, thereby releasing more hydrogen during the entire hydrogen release process.

[0036] This invention provides a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, which is prepared by mechanical ball milling of a supported sample and lithium aluminum hydride; the supported sample is prepared by calcining a precipitate generated by mixing nickel nitrate as nickel source and cerium nitrate as cerium source with sodium hydroxide solution in a certain weight ratio and heating reaction; the supported sample is nickel-supported cerium dioxide or nickel oxide-supported cerium dioxide, named Ni@CeO2 and NiO@CeO2, respectively.

[0037] Here, nickel nitrate is used as the nickel source and cerium nitrate as the cerium source. Depending on the different doping ratios of nickel nitrate and cerium nitrate, the precipitate generated by mixing and heating with sodium hydroxide solution is dried into a solid powder and calcined to obtain Ni@CeO2 or NiO@CeO2. Then, it is mechanically ball-milled with lithium aluminum hydride to obtain nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material.

[0038] Furthermore, Ni@CeO2 is prepared by calcining a precipitate formed by reacting cerium nitrate and nickel nitrate with sodium hydroxide in a weight ratio of 1:0.1; NiO@CeO2 is prepared by calcining a precipitate formed by reacting cerium nitrate and nickel nitrate with sodium hydroxide in a weight ratio of 1:0.3.

[0039] The microstructure of cerium dioxide is nanorod-shaped, while the microstructure of Ni@CeO2 and NiO@CeO2 is nanorod-supported small particles. The doping amount of Ni@CeO2 is 7wt%, and the doping amount of NiO@CeO2 is 1wt% to 10wt%.

[0040] This invention provides a method for preparing a nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, comprising:

[0041] Step 1) Preparation of nickel or nickel oxide-supported cerium dioxide: Nickel nitrate and cerium nitrate are mixed in a certain weight ratio under air conditions and dissolved in deionized water. The mixture is then hydrothermally reacted with sodium hydroxide solution in a reactor. The precipitate generated by the reaction is washed and dried under certain conditions. The resulting sample is then calcined under certain conditions to obtain nickel or nickel oxide-supported cerium dioxide materials, which are named Ni@CeO2 and NiO@CeO2, respectively.

[0042] Step 2) Preparation of nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials: Using Ni@CeO2 or NiO@CeO2 obtained in Step 1 as a catalyst, and mechanically ball-milling with lithium aluminum hydride under certain conditions with a certain doping amount, nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials can be obtained, named LiAlH4 / Ni@CeO2 and LiAlH4 / NiO@CeO2, respectively.

[0043] Here, firstly, nickel nitrate and cerium nitrate are mixed in a certain mass ratio and dissolved in deionized water; a sodium hydroxide solution of a certain proportion is prepared and cooled to room temperature, and then the mixed solution of cerium nitrate and nickel nitrate is slowly added dropwise to the sodium hydroxide solution; then, the mixed solution obtained in the previous step is placed in a reaction vessel for hydrothermal reaction, the generated precipitate is washed and dried, the obtained sample is ground and then calcined under certain conditions to prepare Ni@CeO2 or NiO@CeO2; then, Ni@CeO2 and LiAlH4 are mechanically ball-milled under certain conditions with a certain doping amount to obtain nickel-loaded cerium dioxide-doped lithium aluminum hydride hydrogen storage material, or NiO@CeO2 and LiAlH4 are mechanically ball-milled under certain conditions with a certain doping amount to obtain nickel oxide-loaded cerium dioxide-doped lithium aluminum hydride hydrogen storage material.

[0044] It should be noted that, unless otherwise specified in step 1), the preparation method of nickel-supported cerium dioxide is the same as that of nickel oxide-supported cerium dioxide. The difference lies in the weight ratio of nickel nitrate and cerium nitrate, and the preparation ratio of nickel-supported cerium dioxide material is smaller than that of nickel oxide-supported cerium dioxide material.

[0045] In some embodiments, nickel nitrate and cerium nitrate are mixed in a certain mass ratio to prepare Ni@CeO2 and NiO@CeO2. The weight ratios of cerium nitrate and nickel nitrate used are 1:0.1 and 1:0.3, respectively. The weight of cerium nitrate (Ce(NO3)3·6H2O) in the prepared materials Ni@CeO2 and NiO@CeO2 is about 1.74g.

[0046] Furthermore, when the weight ratio of the mixed cerium nitrate and nickel nitrate is 1:0.1, the product obtained is Ni@CeO2; when the weight ratio of the mixed cerium nitrate and nickel nitrate is 1:0.3, the product obtained is NiO@CeO. 2。

[0047] Furthermore, in step 1), the conditions for adding the mixed aqueous solution of cerium nitrate and nickel nitrate to the sodium hydroxide solution are as follows: the stirring speed is 40 to 60 times / minute under magnetic stirring, the stirring time is 20 to 40 minutes, and 1 to 2 ml is added every 2 minutes.

[0048] Further, in step 2), the hydrothermal reaction temperature is 80 to 120°C, and the reaction time is 20 to 25 hours; the filtration and washing conditions are to wash the precipitate 3 to 4 times with deionized water to wash the strongly alkaline solution to neutrality; the drying conditions are vacuum drying at a temperature of 60 to 80°C for 10 to 12 hours; and the calcination conditions are to heat at a rate of 4 to 8°C / minute under air conditions, at a calcination temperature of 400 to 600°C, and for 2 to 5 hours.

[0049] In some embodiments, the hydrothermal reaction temperature is selected as 100°C and the reaction time is 12 hours; in other embodiments, the product is first dried in a vacuum environment and then calcined in air, with a heating rate of 5 to 8°C / minute, a calcination temperature of 500°C, and a calcination time of 3 to 5 hours.

[0050] Furthermore, in step 2), the NiO@CeO2 doping amount is 1 to 10 wt%; the Ni@CeO2 doping amount is 7 wt%.

[0051] Furthermore, in step 2), the ball milling conditions are as follows: under argon protection, the ball-to-material ratio is (150-300):1, the ball milling speed is 400 to 500 rpm, and the ball milling time is 10 to 15 hours.

[0052] The nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material provided by this invention is used in the field of hydrogen storage. Two different products, Ni@CeO2 and NiO@CeO2, are prepared by using cerium nitrate and nickel nitrate in weight ratios of 1:0.1 and 1:0.3, respectively. When the proportion of nickel decreases, the product changes from NiO to Ni. For NiO@CeO2, when the catalyst doping amount is 1 to 10 wt%, the initial hydrogen release temperature drops to 63.9-93.4℃, the hydrogen release amount reaches 6.7-7.1 wt%, and the hydrogen release rate is 88.94-96.03%. For Ni@CeO2, when the catalyst doping amount is 7 wt%, the hydrogen release temperature drops to 81.4℃, the hydrogen release amount reaches 7 wt%, and the hydrogen release rate is 94.68%.

[0053] The test results of the hydrogen storage material obtained by this invention are as follows:

[0054] To prove the successful preparation of NiO@CeO2 material, X-ray diffraction tests were performed, and the results are as follows: Figure 1As shown, the obtained spectra show diffraction peaks at 28.54°, 33.07°, 47.48°, 56.33°, 59.08°, 69.40°, 76.69°, 79.06°, and 88.41°, corresponding to the (111), (200), (220), (311), (222), (400), (331), (420), and (422) crystal planes of CeO2, respectively. NiO shows diffraction peaks at 37.25°, 43.29°, 62.85°, 75.41°, and 79.37°, corresponding to the (101), (012), (110), (104), and (113) crystal planes of NiO, respectively, indicating that NiO@CeO2 was successfully prepared.

[0055] SEM testing revealed that the Ni@CeO2 and NiO@CeO2 prepared in this invention exhibited a surface structure of small particles supporting nanorods.

[0056] TEM testing revealed the microstructure of Ni@CeO2, with lattice fringes corresponding to the Ni(111) (d = 0.203 nm) and CeO2(111) (d = 0.311 nm) crystal planes. Electron diffraction patterns detected diffraction rings of the Ni(111), CeO2(111), and CeO2(022) crystal planes. EDS spectra showed that Ni, Ce, and O were uniformly distributed. These mapping indices all indicate that the content of Ni and Ce is relatively uniform.

[0057] TEM testing revealed the microstructure of NiO@CeO2, with lattice fringes corresponding to the NiO(012) (d = 0.206 nm) and CeO2(111) (d = 0.316 nm) crystal planes. Electron diffraction patterns detected diffraction rings of the NiO(012) and CeO2(111) crystal planes. EDS spectra showed that Ni, Ce, and O were uniformly distributed. These mapping indices all indicate that the content of Ni and Ce is relatively uniform.

[0058] After temperature-programmed dehydrogenation experiments, when the LiAlH4 / Ni@CeO2 catalyst was doped with 7wt%, the initial hydrogen release temperature dropped to 81.4℃, and the hydrogen release amount reached 7wt%. When the LiAlH4 / NiO@CeO2 catalyst was doped with 7wt%, the initial hydrogen release temperature dropped to 75.4℃, and the hydrogen release amount reached 7.1wt%. It can be seen that Ni@CeO2 and NiO@CeO2 greatly improve the dehydrogenation performance of LiAlH4.

[0059] According to the dehydrogenation kinetics test, LiAlH4 / NiO@CeO2-7 released 0.28wt% of hydrogen in 20 min at 90℃, 4wt% in 50 min at 120℃, 4wt% in 10 min at 150℃, and 6.4wt% in 20 min at 200℃.

[0060] According to the dehydrogenation kinetics test, at 150℃, the initial hydrogen release temperature of LiAlH4 / Ni@CeO2-7 was 81.4℃, the hydrogen release amount was 7wt%, and the hydrogen release rate was 94.68%; the initial hydrogen release temperature of LiAlH4 / NiO@CeO2-7 was 75.4℃, the hydrogen release amount was 7.1wt%, and the hydrogen release rate was 96.03%; and the initial hydrogen release temperature of LiAlH4-7 was 151℃, the hydrogen release amount was 7.54wt%, and the hydrogen release rate was 94.84%.

[0061] This invention improves the performance of hydrogen storage materials by adjusting the morphology of CeO2 and doping with transition metals to achieve a synergistic effect. The technical solution involves adjusting the morphology of CeO2 and using transition metal compounds as catalysts. Small particles supporting nanorods can be observed on the surface under a scanning electron microscope. Ultimately, an initial hydrogen dehydrogenation temperature of 75.4℃ and a hydrogen dehydrogenation amount of 7.1 wt% were achieved. This invention demonstrates a good hydrogen dehydrogenation amount while maintaining a relatively low initial dehydrogenation temperature, effectively preparing highly catalytically active catalyst materials.

[0062] The preparation method of the above-mentioned nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material is described below with some specific examples. However, it should be noted that these specific examples are only for better illustrating the present invention and do not constitute an improper limitation of the present invention.

[0063] Example 1

[0064] This invention provides a method for preparing a nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, comprising the following steps:

[0065] Step 1) Under air conditions, dissolve nickel nitrate and cerium nitrate in deionized water at a mass ratio of 1:0.3 to obtain a mixed solution; cool the prepared NaOH solution to room temperature, measure the NaOH solution and the mixed solution of nickel nitrate and cerium nitrate according to a volume ratio of 5:1, and magnetically stir the solvent at a speed of 50 rpm / min. While stirring, add the mixed solution of cerium nitrate and nickel nitrate dropwise to the NaOH solution, and stir for 30 min.

[0066] Step 2) Preparation of nickel oxide supported on cerium dioxide: The mixed solution obtained in step 1 is placed in a reaction vessel and subjected to hydrothermal reaction at 100℃ for 24 hours. After the reaction is completed, the precipitate is washed 4 times with deionized water and then vacuum dried in a vacuum oven at 80℃ for 12 hours. The sample is then calcined at 500℃ for 3 hours with a heating rate of 5℃ / min to obtain nickel oxide supported on cerium dioxide, named NiO@CeO2.

[0067] Step 3) Preparation of nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material: Using the NiO@CeO2 obtained in step 2 as a catalyst, 0.021 g of NiO@CeO2 and 0.279 g of lithium aluminum hydride were weighed under an argon atmosphere. The ball-to-material ratio was 200:1, the ball milling speed was 500 r / min, and the ball milling time was 15 h. A nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material with a NiO@CeO2 doping amount of 7 wt% was obtained and named LiAlH4 / NiO@CeO2-7.

[0068] To prove the successful preparation of NiO@CeO2 material, X-ray diffraction tests were performed on it, and the results are as follows: Figure 1 As shown, the obtained spectra show diffraction peaks at 28.54°, 33.07°, 47.48°, 56.33°, 59.08°, 69.40°, 76.69°, 79.06°, and 88.41°, corresponding to the (111), (200), (220), (311), (222), (400), (331), (420), and (422) crystal planes of CeO2, respectively. The diffraction peaks of nickel oxide at 37.25°, 43.29°, 62.85°, 75.41°, and 79.374°, corresponding to the (101), (012), (110), (104), and (113) crystal planes of nickel oxide, respectively, indicating that NiO@CeO2 was successfully prepared.

[0069] To demonstrate the structural characteristics of NiO@CeO2 material, SEM testing was conducted, and the results showed that... Figure 3 As shown, the material structure prepared by this invention exhibits a uniformly dispersed particle structure, indicating that nickel oxide is loaded onto cerium dioxide nanorods. SEM analysis reveals that the NiO@CeO2 prepared in this invention has a small particle-loaded nanorod surface structure.

[0070] To further confirm the composition of NiO@CeO2, TEM testing was conducted, and the results proved that... Figure 4As shown, fine lattice fringes correspond to the crystal planes of Ni(012) (d = 0.206 nm) and CeO2(111) (d = 0.316 nm). Electron diffraction patterns can detect diffraction rings of Ni(012), CeO2(111), and CeO2(022) crystal planes. EDS spectra show that Ni, Ce, and O are uniformly distributed. These mapping indices all indicate that the content of Ni and Ce is relatively uniform.

[0071] To demonstrate the hydrogen dehydrogenation kinetics performance of the LiAlH4 / NiO@CeO2-7 hydrogen storage material, the test method was as follows: An appropriate amount of sample (50mg-80mg) was weighed, and the temperature was increased to 300℃ at a rate of 2℃ / min to test the hydrogen desorption performance of the storage material. The test results are as follows: Figure 7 As shown, its hydrogen release temperature is 75.40℃, and when the temperature is raised to 300℃, the hydrogen release temperature is 7.1wt%, and the hydrogen release rate reaches 96.03% of the theoretical value.

[0072] To further demonstrate the hydrogen dehydrogenation kinetics performance of the LiAlH4 / NiO@CeO2-7 hydrogen storage material, isothermal dehydrogenation tests were conducted at different temperatures. The test results are as follows: Figure 8 As shown, at 90℃, LiAlH4 / NiO@CeO2-7 was named LiAlH4 / NiO@CeO2-90 after 20 min, with a hydrogen release of 0.28 wt%; at 120℃, LiAlH4 / NiO@CeO2-7 was named LiAlH4 / NiO@CeO2-120 after 50 min, with a hydrogen release of 4.0 wt%; at 150℃, LiAlH4 / NiO@CeO2-7 was named LiAlH4 / NiO@CeO2-150 after 10 min, with a hydrogen release of 4.0 wt%; and at 200℃, LiAlH4 / NiO@CeO2-7 was named LiAlH4 / NiO@CeO2-200 after 20 min, with a hydrogen release of 6.4 wt%. Based on the above test results, LiAlH4 / NiO@CeO2-7 with a content of 7wt% exhibits good hydrogen desorption performance.

[0073] To demonstrate the roles of cerium nitrate as a cerium source and nickel nitrate as a nickel source in the scheme, Comparative Examples 2 and 3 are provided, which are lithium aluminum hydride hydrogen storage materials prepared by separately doping cerium dioxide and nickel oxide, respectively. Comparative Example 1 is a pure lithium aluminum hydride hydrogen storage material without any catalyst. By comparing the dehydrogenation kinetics test, it can be seen that the catalyst synthesized in Example 1 has the best performance.

[0074] Comparative Example 1

[0075] A method for preparing lithium aluminum hydride hydrogen storage material without adding NiO@CeO2, i.e., lithium aluminum hydride hydrogen storage material with NiO@CeO2 content of 0wt%, wherein the steps unless otherwise specified are the same as in Example 1, except that in step 2, NiO@CeO2 is not added, i.e. only 0.30g of lithium aluminum hydride is weighed.

[0076] The obtained lithium aluminum hydride hydrogen storage material with a NiO@CeO2 content of 0 wt% was subjected to a temperature-induced dehydrogenation test. The test results were consistent with those obtained by [previous test]. Figure 7 As shown, its initial hydrogen release temperature is 151℃, and when the temperature is raised to 300℃, the amount of hydrogen released is 7.54wt%, and the hydrogen release rate reaches 94.84% of the theoretical value.

[0077] As shown in Example 1 and Comparative Example 1, NiO@CeO2 as a catalyst reduced the initial hydrogen desorption temperature of lithium aluminum hydride from 151°C to 75.4°C and increased the hydrogen desorption rate from 94.84% to 96.03%.

[0078] Comparative Example 2

[0079] A method for preparing cerium dioxide-doped lithium aluminum hydride hydrogen storage material is provided. Unless otherwise specified, the steps are the same as in Example 1, except that: in step 1, a cerium nitrate solution is prepared without nickel nitrate doping; the material obtained in step 2 is named CeO2; in step 3, cerium dioxide-doped lithium aluminum hydride hydrogen storage material is obtained with a doping amount of 7wt%, and the cerium dioxide-doped lithium aluminum hydride hydrogen storage material is named LiAlH4 / CeO2-7.

[0080] The obtained cerium dioxide-doped lithium aluminum hydride hydrogen storage material was subjected to a temperature-induced dehydrogenation test, using the same method as in Example 1. The test results are as follows. Figure 7 As shown, its hydrogen release temperature is 82.6℃, and the amount of hydrogen released when the temperature is raised to 300℃ is 7wt%, with the hydrogen release rate reaching 94.48% of the theoretical value.

[0081] The comparison between Example 1 and Comparative Example 2 shows that the initial temperature of LiAlH4 / CeO2-7 decreased from 82.6℃ to 75.4℃, and the hydrogen release rate increased from 7wt% to 7.1wt%. The comparison between Actual Comparative Example 1 and Comparative Example 2 shows that the initial temperature of LiAlH4 / CeO2-7 decreased from 151℃ to 82.6℃. It is evident that the addition of cerium dioxide can lower the initial hydrogen release temperature and increase the hydrogen release rate, significantly improving the hydrogen release performance of LiAlH4.

[0082] Comparative Example 3

[0083] A method for preparing a nickel oxide-doped lithium aluminum hydride hydrogen storage material, wherein the steps unless otherwise specified are the same as those in Example 1, except that: in step 1, a nickel nitrate solution is prepared without doping with cerium nitrate; the nickel oxide material obtained in step 2 is named NiO; and in step 3, the nickel oxide-doped lithium aluminum hydride hydrogen storage material is obtained with a doping amount of 7wt%, named LiAlH4 / NiO-7.

[0084] The obtained nickel oxide-doped lithium aluminum hydride hydrogen storage material was subjected to a temperature-induced dehydrogenation test, using the same method as in Example 1. The test results are as follows. Figure 7 As shown, its initial hydrogen release temperature is 79.5℃, and the amount of hydrogen released when the temperature is raised to 300℃ is 7.1wt%, with a hydrogen release rate of 96.03% of the theoretical value.

[0085] A comparison of Example 1 and Comparative Example 3 shows that the initial dehydrogenation temperature of LiAlH4 / NiO-7 decreased from 79.5℃ to 74.6℃. Comparative Examples 1 and 3 show that the initial dehydrogenation temperature decreased from 151℃ to 79.50℃, and the hydrogen release rate increased from 94.51% to 96.03%. This demonstrates that adding nickel oxide can lower the initial hydrogen release temperature, increase the hydrogen release rate, and improve the hydrogen release performance of LiAlH4.

[0086] The following conclusions can be drawn from Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3: Cerium dioxide and nickel oxide as catalysts for doping lithium aluminum hydride hydrogen storage materials have significant effects on reducing the initial hydrogen release temperature and increasing the hydrogen release rate.

[0087] Example 2

[0088] A method for preparing a nickel-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material is provided. The steps not specifically described are the same as those in Example 1, except that: in step 1, the weight ratio of cerium nitrate and nickel nitrate is 1:0.1; the material obtained in step 2 is named Ni@CeO2; and the step yields a nickel-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material with a doping amount of 7wt%, named LiAlH4 / Ni@CeO2-7.

[0089] To demonstrate the structural characteristics of the Ni@CeO2 material, SEM testing was conducted, and the results showed that... Figure 2 As shown, the material structure prepared by this invention exhibits an agglomeration phenomenon.

[0090] To further demonstrate the structural characteristics of Ni@CeO2 material, TEM testing revealed lattice fringes corresponding to the Ni(111) (d = 0.203 nm) and CeO2(111) (d = 0.311 nm) crystal planes. Electron diffraction patterns detected diffraction rings of the Ni(111), CeO2(111), and CeO2(022) crystal planes. EDS spectra showed that Ni, Ce, and O were uniformly distributed. These mapping indices all indicate that the content of Ni and Ce is relatively uniform.

[0091] Comparing Example 1 and Example 2, the synthesized substances changed as the doping ratio of cerium nitrate and nickel nitrate decreased, resulting in the appearance of elemental Ni instead of NiO, thus producing Ni@CeO2 and NiO@CeO2.

[0092] The obtained Ni@CeO2-doped lithium aluminum hydride hydrogen storage material was subjected to a temperature-induced dehydrogenation test, using the same method as in Example 1. The test results are as follows. Figure 7 As shown, its initial hydrogen release temperature is 81.4℃, and when the temperature is raised to 300℃, the amount of hydrogen released is 7wt%, and the hydrogen release rate reaches 94.68% of the theoretical value.

[0093] To further demonstrate the dehydrogenation performance, isothermal dehydrogenation tests were conducted on LiAlH4, LiAlH4 / NiO@CeO2-7, and LiAlH4 / Ni@CeO2-7. The results are as follows: Figure 9 As shown, at 150℃, LiAlH4 was named LiAlH4-150 after 37 min, with a hydrogen release of 0.5 wt%; at 150℃, LiAlH4 / NiO@CeO2-7 was named LiAlH4 / NiO@CeO2-150 after 13 min, with a hydrogen release of 4.4 wt%; at 150℃, LiAlH4 / Ni@CeO2-7 was named LiAlH4 / Ni@CeO2-150 after 22 min, with a hydrogen release of 4.4 wt%.

[0094] Example 3

[0095] A method for preparing a nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material (NiO@CeO2 content of 1wt%) is provided. The steps unless otherwise specified are the same as in Example 1, except that in step 2, the amount of NiO@CeO2 added is 1wt%, and 0.003g of NiO@CeO2 and 0.297g of LiAlH4 are weighed in an argon atmosphere glove box.

[0096] The obtained lithium aluminum hydride hydrogen storage material with a Ni@CeO2 content of 1 wt% was subjected to a temperature-induced dehydrogenation test. The test method was the same as in Example 1, and the test results are as follows. Figure 7As shown, its initial hydrogen release temperature is 93.5℃, and the amount of hydrogen released when the temperature is raised to 300℃ is 7wt%, with a hydrogen release rate of 88.94% of the theoretical value.

[0097] Example 4

[0098] A method for preparing a nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material (NiO@CeO2 content of 3wt%) is provided. The steps not specifically described are the same as those in Example 1, except that in step 2, the amount of NiO@CeO2 added is 3wt%, and 0.009g of NiO2@C and 0.291g of LiAlH4 are weighed in an argon atmosphere glove box.

[0099] The obtained lithium aluminum hydride hydrogen storage material with a NiO@CeO2 content of 3wt% was subjected to a temperature-induced dehydrogenation test. The test method was the same as in Example 1, and the test results are as follows. Figure 7 As shown, its initial hydrogen release temperature is 79.5℃, and when the temperature is raised to 300℃, the amount of hydrogen released is 7wt%, and the hydrogen release rate reaches 90.77% of the theoretical value.

[0100] Example 5

[0101] A method for preparing a nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material (NiO@CeO2 content of 10wt%) is provided. The steps not specifically described are the same as those in Example 1, except that in step 2, the amount of NiO@CeO2 added is 10wt%, and 0.03g of NiO@CeO2 and 0.27g of LiAlH4 are weighed in an argon atmosphere glove box.

[0102] The obtained lithium aluminum hydride hydrogen storage material with a NiO@CeO2 content of 10 wt% was subjected to a temperature-induced dehydrogenation test. The test method was the same as in Example 1, and the test results are as follows. Figure 7 As shown, its initial hydrogen release temperature is 63.9℃, and when the temperature is raised to 300℃, the amount of hydrogen released is 6.70wt%, and the hydrogen release rate reaches 93.64% of the theoretical value.

[0103] The Ni and NiO particles prepared in this invention can be loaded onto CeO2 nanorods to form an effective catalyst that improves the hydrogen storage performance of LiAlH4. The hydrogen storage material prepared in this invention can effectively improve the hydrogen desorption performance of lithium aluminum hydride. When LiAlH4 / NiO@CeO2-7 is used, the initial hydrogen desorption temperature drops to 75.40℃, and the final hydrogen desorption amount reaches 7.1wt%. This invention obtains two different products by using different weight ratios of cerium nitrate and nickel nitrate, and explores the catalytic effects of the two substances. Both can improve the catalytic performance of hydrogen storage materials. Through specific experimental comparison, the catalytic effect of NiO@CeO2 is better. The method used to prepare NiO@CeO2 in this invention produces products with high consistency. It uses uniformly purchased cerium nitrate and nickel nitrate, and the calcination environment is in air to prepare oxides, resulting in higher sample purity.

[0104] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of the invention, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the invention. The sequence numbers of the above-described embodiments of the invention are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0105] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0106] The methods disclosed in the several method embodiments provided by this invention can be arbitrarily combined to obtain new method embodiments without conflict. The features disclosed in the several method or device embodiments provided by this invention can be arbitrarily combined to obtain new method or device embodiments without conflict.

[0107] The above description is merely an embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material, characterized in that, The loaded sample was prepared by mechanical ball milling with lithium aluminum hydride; the loaded sample was prepared by calcining the precipitate generated by mixing nickel nitrate as nickel source and cerium nitrate as cerium source with sodium hydroxide solution in a certain weight ratio and heating reaction; the loaded sample was nickel-loaded cerium dioxide or nickel oxide-loaded cerium dioxide, named Ni@CeO2 and NiO@CeO2, respectively. The Ni@CeO2 is prepared at a weight ratio of 1: The NiO@CeO2 is prepared by calcining the precipitate formed by the reaction of 0.1% cerium nitrate and nickel nitrate with sodium hydroxide; the NiO@CeO2 is prepared by calcining the precipitate formed by the reaction of cerium nitrate and nickel nitrate with sodium hydroxide in a weight ratio of 1:0.

3. The cerium dioxide has a nanorod-like microstructure, while Ni@CeO2 and NiO@CeO2 have nanorod-supported small particles. The doping amount of Ni@CeO2 is 7wt%, and the doping amount of NiO@CeO2 is 1wt% to 10wt%. The preparation method of nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material is as follows: Step 1) Preparation of nickel or nickel oxide-supported cerium dioxide: Nickel nitrate and cerium nitrate are mixed in air at a certain weight ratio and dissolved in deionized water. The mixture is then hydrothermally reacted with sodium hydroxide solution in a reactor. The precipitate generated by the reaction is washed and dried under certain conditions. The resulting sample is then calcined under certain conditions to obtain nickel or nickel oxide-supported cerium dioxide materials, which are named Ni@CeO2 and NiO@CeO2, respectively. The conditions for adding the mixed aqueous solution of cerium nitrate and nickel nitrate to sodium hydroxide solution are as follows: the stirring speed is 40 to 60 times / minute under magnetic stirring, the stirring time is 20 to 40 minutes, and 1 to 2 ml is added dropwise every 2 minutes. The hydrothermal reaction is carried out at a temperature of 80 to 120°C for a duration of 20 to 25 hours. The washing conditions are to wash the precipitate 3 to 4 times with deionized water; The drying conditions are vacuum drying, with a drying temperature of 60 to 80°C and a drying time of 10 to 12 hours; The calcination conditions are as follows: heating rate of 4 to 8 °C / min under air conditions, calcination temperature of 400 to 600 °C, and calcination time of 2 to 5 hours. Step 2) Preparation of nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials: Using Ni@CeO2 or NiO@CeO2 obtained in Step 1 as a catalyst, and mechanically ball-milling with lithium aluminum hydride under certain conditions with a certain doping amount, nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage materials can be obtained, named LiAlH4 / Ni@CeO2 and LiAlH4 / NiO@CeO2, respectively.

2. The application of the nickel or nickel oxide-supported cerium dioxide-doped lithium aluminum hydride hydrogen storage material according to claim 1 in the field of hydrogen storage is characterized in that: When the doping amount of Ni@CeO2 as a catalyst is 7wt%, the hydrogen release temperature of the system drops to 81.4℃, and the hydrogen release amount reaches 7wt%; when the doping amount of NiO@CeO2 as a catalyst is 7wt%, the hydrogen release temperature of the system drops to 75.4℃, and the hydrogen release amount reaches 7.1wt%; when the doping amount of NiO@CeO2 as a catalyst is 1 to 10wt%, the initial hydrogen release temperature drops to 63.9 to 93.4℃, the hydrogen release amount reaches 6.7 to 7.1wt%, and the hydrogen release rate is 88.94% to 96.03%.

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