A porous spinel type nickel cobaltate and a preparation method and application thereof

Abstract

The application discloses porous spinel type nickel cobaltate and a preparation method and application thereof, and belongs to the technical field of hydrogen storage materials. The porous spinel type nickel cobaltate has a three-dimensional connected porous structure, and the preparation method comprises the following steps: firstly, nickel, cobalt and aluminum metal elements are smelted into a nickel-cobalt-aluminum ternary alloy by using a smelting method, and the alloy is mechanically crushed; then, the alloy powder is poured into a sodium hydroxide solution for dealloying treatment, and the treated solid product is washed and dried to obtain porous nickel-cobalt solid solution powder; finally, the porous nickel-cobalt solid solution powder is placed in a muffle furnace in an air atmosphere for oxidation treatment, and the target product can be obtained. The preparation method of the porous spinel type nickel cobaltate has the advantages of using non-precious nickel, cobalt and aluminum metals as initial raw materials, wide source, low cost, simple process, safety and reliability, and easy scale production. The prepared porous spinel type nickel cobaltate can be applied to sodium aluminum hydride hydrogen storage, can significantly reduce the hydrogen release temperature of sodium aluminum hydride, and has a high hydrogen release amount.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials technology, specifically relating to a porous spinel-type nickel cobalt oxide, its preparation method, and its application in sodium aluminum hydride hydrogen storage. Background Technology

[0002] Hydrogen is considered an ideal secondary energy source for the future, and its safe and efficient storage and transportation are crucial for the large-scale application of hydrogen and the development of a hydrogen economy. Compared to high-pressure gaseous and cryogenic liquid hydrogen storage, solid-state hydrogen storage offers advantages such as safety, reliability, and high storage density. Among these, sodium aluminum hydride (NaAlH4), a representative coordination hydride hydrogen storage material, boasts advantages such as high hydrogen storage capacity and low cost, making it an important solid-state hydrogen storage material. However, NaAlH4 exhibits high thermodynamic stability and a high activation energy for the hydrogen release reaction, requiring relatively high temperatures for effective hydrogen release, which significantly limits its practical application. Catalyst doping is one of the main methods to lower the hydrogen release temperature of NaAlH4 and improve its reversibility, with transition metal oxide catalysts being a typical example.

[0003] Spinel-type nickel cobalt oxide (NiCo2O4) possesses advantages such as good electrical conductivity, high electrochemical activity, abundant resources, and environmental friendliness, making it widely applicable in energy storage and conversion fields such as hydrogen / electricity. Porous spinel-type NiCo2O4 exhibits a three-dimensional interconnected porous structure, resulting in a larger specific surface area and more active sites, thus demonstrating better catalytic performance. Currently, the main methods for preparing porous spinel-type NiCo2O4 include hydrothermal methods, solvothermal methods, microwave-assisted methods, template methods, and sol-gel methods. For example, Kim et al. synthesized porous flower-like NiCo2O4 on nickel foam using cobalt chloride hexahydrate and nickel chloride hexahydrate as raw materials via a hydrothermal method. However, the process is cumbersome, has low production efficiency, and requires nickel foam as a substrate or base [Tae Hyun Kim, Ganesh Kumar Veerasubramani, Sang Jae Kim, Journal of Industrial and Engineering Chemistry, 2018, 61: 181-187]. Li et al. synthesized three-dimensional hierarchical NiCo2O4 using a solvothermal method combined with calcination, but it is difficult to mass-produce and has safety risks [Li Qun, Zhang Kuo, Li Yanhua, et al., Journal of Composite Materials, 2024, 41(1): 281-292]. Lei et al. synthesized three-dimensional layered NiCo2O4 microspheres using a microwave-assisted method, but the operation is complicated and difficult to scale up [Ying Lei, Jing Li, Yanyan Wang, et al., ACS Applied Materials Interfaces, 2014, 6(3): 1773-1780]. Bai et al. used silica sol as a template to prepare three-dimensional porous NiCo2O4 composite materials, but the preparation process is cumbersome, time-consuming, and the material morphology and structure are monotonous [Yang Bai, Ranran Wang, Xiaoyu Lu, et al., Journal of Colloid and Interface Science, 2016, 468: 1-9].

[0004] In summary, although significant progress has been made both domestically and internationally in the preparation of porous spinel-type NiCo2O4 catalysts, they still cannot fully meet the demands of practical applications for high performance, low cost, and ease of large-scale production. Furthermore, for hydrogen storage applications, the hydrogen desorption temperature of NaAlH4 remains relatively high. Summary of the Invention

[0005] This invention addresses the shortcomings of existing porous NiCo2O4 preparation technology and NaAlH4 hydrogen storage technology by providing a porous spinel-type NiCo2O4 and a simple, low-cost, safe and reliable preparation method, with the aim of applying it to NaAlH4 hydrogen storage and significantly reducing the hydrogen desorption temperature of NaAlH4.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The porous spinel-type NiCo2O4 provided by this invention has a three-dimensional interconnected porous structure, and its preparation includes the following steps:

[0008] (1) Nickel, cobalt and aluminum metals with a molar ratio of 1:2:13 to 20 are melted into nickel-cobalt-aluminum ternary alloy by smelting method, and the alloy is mechanically crushed into powder with a particle size of less than 200 mesh.

[0009] (2) The alloy powder obtained in step (1) is poured into sodium hydroxide solution for dealloying treatment, and the treated solid product is washed and dried to obtain porous nickel-cobalt solid solution powder.

[0010] (3) The porous nickel-cobalt solid solution powder obtained in step (2) is placed in a muffle furnace in an air atmosphere for oxidation treatment to obtain porous spinel type NiCo2O4.

[0011] As an optimization, in the preparation step (2), the concentration of sodium hydroxide solution is 2-3 mol / L, the temperature is 25-30℃, and the dealloying time is 8-12h.

[0012] As an optimization, the oxidation treatment in the preparation step (3) is carried out at a temperature of 400-500°C for 4-8 hours.

[0013] This invention also provides the application of the porous spinel-type NiCo2O4 obtained by the above preparation method in NaAlH4 hydrogen storage materials, specifically by mechanically mixing porous spinel-type NiCo2O4 with NaAlH4, wherein the amount of NiCo2O4 added is 10-40 wt.%.

[0014] As an optimization, the amount of NiCo2O4 added is 20 wt.%.

[0015] The innovation of this invention is as follows:

[0016] This invention uses a nickel-cobalt-aluminum ternary alloy as a precursor to obtain a porous NiCo2O4 catalyst through a two-step dealloying and oxidation process. During dealloying, the extraction of aluminum and the rearrangement of nickel and cobalt atoms result in a nickel-cobalt solid solution, achieving both uniform atomic-scale distribution of components and the formation of fine and porous particles. A simple, controllable oxidation process ensures that no oxide phase separation occurs during oxidation, resulting in porous spinel-type NiCo2O4. In applications with NaAlH4 hydrogen storage materials, spinel-type NiCo2O4 can promote charge migration between sodium ions and [AlH4] ion clusters, reducing the Al-H bond binding energy and thus lowering the hydrogen desorption temperature of NaAlH4. Simultaneously, porous NiCo2O4 possesses a larger specific surface area and more active sites, thereby exhibiting stronger catalytic efficacy.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The preparation method of porous spinel NiCo2O4 provided is simple, safe and reliable, and easy to scale up.

[0019] (2) The method for preparing porous spinel-type NiCo2O4 provided uses non-precious nickel, cobalt and aluminum metals as initial raw materials, which are widely available and inexpensive.

[0020] (3) The porous spinel-type NiCo2O4 provided is used as a catalyst for NaAlH4 hydrogen storage material, which can reduce the initial hydrogen release temperature of NaAlH4 to 86℃ and has a high hydrogen release capacity. Attached Figure Description

[0021] Figure 1 The X-ray diffraction pattern of the porous nickel-cobalt solid solution in Example 1 of the present invention is shown.

[0022] Figure 2 This is the X-ray diffraction pattern of porous spinel-type NiCo2O4 in Example 1 of the present invention.

[0023] Figure 3 This is a scanning electron microscope image of the porous spinel-type NiCo2O4 in Example 1 of the present invention.

[0024] Figure 4 The heating and hydrogen release curves of NaAlH4-based hydrogen storage material and pure NaAlH4 in Example 1 of this invention are shown.

[0025] Figure 5 The heating and hydrogen release curves of the NaAlH4-based hydrogen storage material in Example 2 of this invention are shown. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] A nickel-cobalt-aluminum ternary alloy was formed by melting nickel sheets, cobalt granules, and aluminum sheets in a molar ratio of 1:2:17 using vacuum induction melting. The alloy was then mechanically pulverized into powder with a particle size of less than 200 mesh. The alloy powder was then subjected to a dealloying treatment in a 3 mol / L sodium hydroxide solution at 25°C for 8 hours. The dealloyed solid product was washed successively with distilled water and alcohol, and then vacuum dried to obtain a porous nickel-cobalt solid solution powder (its X-ray diffraction pattern is shown below). Figure 1 (As shown); porous nickel-cobalt solid solution powder is placed in a muffle furnace and oxidized in air (temperature 500℃, time 4h) to obtain the porous spinel-type NiCo2O4. Figure 2 and Figure 3 It is evident that the obtained porous spinel-type NiCo2O4 consists of a single NiCo2O4 phase and possesses a three-dimensionally interconnected porous structure. 20 wt.% of the porous spinel-type NiCo2O4 was mixed with NaAlH4 using mechanical ball milling. Figure 4 It can be seen that the obtained NaAlH4-based hydrogen storage material starts to release hydrogen at 86℃ and basically ends at 230℃, with a hydrogen release amount of about 4.4 wt.%. In comparison, the initial hydrogen release temperature of pure NaAlH4 is as high as 175℃, and the end hydrogen release temperature is higher than 300℃.

[0029] Example 2

[0030] A nickel-cobalt-aluminum ternary alloy was formed by melting nickel sheets, cobalt granules, and aluminum sheets in a molar ratio of 1:2:17 using vacuum induction melting. The alloy was then mechanically pulverized into powder with a particle size less than 200 mesh. The alloy powder was then subjected to a dealloying treatment in a 3 mol / L sodium hydroxide solution at 25°C for 8 hours. The dealloyed solid product was washed successively with distilled water and alcohol, followed by vacuum drying to obtain porous nickel-cobalt solid solution powder. This porous nickel-cobalt solid solution powder was then placed in a muffle furnace and oxidized in air (at 450°C for 8 hours) to obtain the porous spinel-type NiCo2O4. 15 wt.% of the porous spinel-type NiCo2O4 was mixed with NaAlH4 using mechanical ball milling. Figure 5 It can be seen that the obtained NaAlH4-based hydrogen storage material begins to release hydrogen at 95°C and the hydrogen release basically ends at 250°C, with a hydrogen release amount of approximately 4.7 wt.%.

[0031] Example 3

[0032] A nickel-cobalt-aluminum ternary alloy was formed by melting nickel sheets, cobalt granules, and aluminum sheets in a molar ratio of 1:2:13 using vacuum induction melting. The alloy was then mechanically pulverized into powder with a particle size of less than 200 mesh. The alloy powder was then subjected to a dealloying treatment in a 2 mol / L sodium hydroxide solution at 25°C for 10 hours. The dealloyed solid product was washed successively with distilled water and alcohol, and then vacuum dried to obtain porous nickel-cobalt solid solution powder. The porous nickel-cobalt solid solution powder was then placed in a muffle furnace and oxidized in air (at a temperature of 400°C for 8 hours) to obtain the porous spinel-type NiCo2O4. Mechanically mixing 10 wt.% of the porous spinel-type NiCo2O4 with NaAlH4 significantly reduced the hydrogen desorption temperature of NaAlH4.

[0033] Example 4

[0034] A nickel-cobalt-aluminum ternary alloy was formed by melting nickel sheets, cobalt granules, and aluminum sheets in a molar ratio of 1:2:20 using vacuum induction melting. The alloy was then mechanically pulverized into powder with a particle size of less than 200 mesh. The alloy powder was then subjected to a dealloying treatment in a 3 mol / L sodium hydroxide solution at 30°C for 12 hours. The dealloyed solid product was washed successively with distilled water and alcohol, and then vacuum dried to obtain porous nickel-cobalt solid solution powder. The porous nickel-cobalt solid solution powder was then placed in a muffle furnace and oxidized in air (at a temperature of 450°C for 6 hours) to obtain the porous spinel-type NiCo2O4. Mechanically mixing 40 wt.% of the porous spinel-type NiCo2O4 with NaAlH4 significantly reduced the hydrogen desorption temperature of NaAlH4.

Claims

1. A porous spinel-type nickel cobaltate characterized by, The spinel-type nickel cobaltate has a three-dimensional interconnected porous structure, and a preparation method thereof comprises the following steps: (1) using a smelting method to smelt nickel, cobalt and aluminum metal elements with a molar ratio of 1:2:13-20 into a nickel-cobalt-aluminum ternary alloy, and mechanically crushing the alloy into a powder with a particle size of less than 200 mesh; (2) pouring the alloy powder obtained in step (1) into a sodium hydroxide solution for dealloying treatment, and washing and drying the treated solid product to obtain a porous nickel-cobalt solid solution powder; the concentration of the sodium hydroxide solution is 2-3 mol / L, the temperature is 25-30 ℃, and the dealloying time is 8-12 h; (3) placing the porous nickel-cobalt solid solution powder obtained in step (2) in a muffle furnace in an air atmosphere for oxidation treatment, and spinel-type nickel cobaltate is obtained; the oxidation treatment temperature is 400-500 ℃, and the time is 4-8 h.

2. The application of the porous spinel-type nickel cobaltate in claim 1 in sodium aluminum hydride hydrogen storage material.

3. Use of the porous spinel-type nickel cobaltate according to claim 2 in sodium aluminum hydride hydrogen storage material, characterized in that, The porous spinel-type nickel cobaltate is mechanically mixed with sodium aluminum hydride, and the addition amount of the nickel cobaltate is 10-40 wt.%.

4. Use of the porous spinel-type nickel cobaltate according to claim 3 in sodium aluminum hydride hydrogen storage material, characterized in that, The addition amount of the nickel cobaltate is 20 wt.%.

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