Preparation method of composite hydrogen storage material and product thereof

Abstract

The application discloses a preparation method of a composite hydrogen storage material, and is characterized in that the method comprises the following steps: adding graphite oxide into ultrapure water, ultrasonicating, then adding Co(NO3)2.6H2O and NiCl.6H2O and dissolving; adding triethanolamine, uniformly stirring, and heating at 80-100 DEG C for 12-15 hours; after cooling, centrifuging and washing the obtained precipitate; drying at 60 DEG C for 6-8 hours; heating to 300-400 DEG C in a nitrogen flow, once heat preservation, then continuously heating to 500-550 DEG C, twice heat preservation, cooling, and obtaining CoNi-CoO@rGO; and ball-milling MgH2 and CoNi-CoO@rGO, and keeping an argon atmosphere all the time. The application further discloses the composite hydrogen storage material obtained by the preparation method. The application has good catalytic effect, significantly optimizes the hydrogen storage kinetics of MgH2, has a lower initial hydrogen absorption temperature, and has good hydrogen absorption kinetics performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to hydrogen storage materials and its preparation method, and specifically relates to a preparation method of a composite hydrogen storage material and a product obtained by the method. BACKGROUND

[0002] Traditional fossil energy such as oil and coal is becoming increasingly depleted with the continuous use of human beings, and the resulting energy crisis restricts the development of human society. Finding green and efficient renewable new energy to replace fossil energy has become the consensus of all mankind, and a large amount of research results have been achieved. Hydrogen energy has advantages such as rich raw material sources, high energy density, environmentally friendly products, and renewability, and has become one of the most potential alternative energies. At present, the development and utilization of hydrogen energy mainly faces three key problems of production, storage and transportation. Among them, how to safely and efficiently use hydrogen energy as a vehicle-mounted energy storage carrier is the most challenging and commercially valuable research topic. Traditional high-pressure liquid and gaseous hydrogen storage has low efficiency, high energy consumption and low safety, which restricts the commercial use of vehicle-mounted hydrogen storage. As a safe and efficient hydrogen storage method, solid-state hydrogen storage technology has great research potential and is the most likely to be used on a large scale in the future.

[0003] Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6wt%) and good reversibility, and is considered to be one of the most potential solid-state hydrogen storage materials. However, its high thermal stability and slow kinetics seriously restrict its use as a vehicle-mounted energy storage carrier.

[0004] In recent years, researchers have improved the hydrogen storage performance of MgH2 by means of doping modification, nanocrystallization, composite system construction and confinement, i.e. reducing the hydrogen absorption / desorption temperature, improving the hydrogen absorption / desorption kinetics and reversibility. Among them, doping modification, i.e. adding carbon-based materials and various transition metal compounds (oxides, chlorides and nitrides, etc.), is the most studied. It has been reported that carbon-based materials as carriers of MgH2 hydrogen storage catalysts (such as MWCNT, etc.) have almost no catalytic effect, and transition metal compounds such as TiO2, NiCl2, NiO, Nb2O5 and TiN as catalysts can effectively improve the hydrogen storage performance of MgH2, but they have no special morphology as support to further improve the hydrogen storage performance of MgH2.

[0005] The existing hydrogen storage catalyst preparation process is relatively complicated, and the ball milling process usually takes a long time, sometimes even several days. This not only consumes time, but also increases energy costs and equipment wear and tear, thereby increasing the cost of preparation. Moreover, during the evacuation process, the evacuation system must be able to maintain the required atmosphere conditions to ensure that the sample is not affected by humidity, oxygen or other pollutants in the external air. If the atmosphere control is not proper, it may affect the quality and performance of the sample. SUMMARY

[0006] The application aims to provide a preparation method of a composite hydrogen storage material for improving the kinetic and thermodynamic properties of magnesium hydride, and to provide a composite hydrogen storage material with a low initial hydrogen absorption temperature and good hydrogen absorption kinetic properties.

[0007] The application provides a preparation method of a composite hydrogen storage material.

[0008] In step one, graphite oxide is added to ultrapure water, ultrasonic treatment is performed, and then Co(NO3)2·6H2O and NiCl·6H2O are added and dissolved.

[0009] In step two, triethanolamine is added to the solution obtained in step one, stirring is performed until uniform, and heating is performed at 80-100 DEG C for 12-15 hours.

[0010] In step three, after the product obtained in step two is cooled, centrifugation and washing are performed on the obtained precipitate.

[0011] In step four, the product obtained in step three is dried at 60-80 DEG C for 6-8 hours.

[0012] In step five, the product obtained in step four is heated to 300-400 DEG C in a nitrogen stream, one-time heat preservation is performed, then heating is continued to 500-550 DEG C, two-time heat preservation is performed, cooling is performed, and CoNi-CoO@rGO is obtained.

[0013] In step six, MgH2 is ball milled with CoNi-CoO@rGO, an argon atmosphere is maintained all the time, the speed is 300-400 r / min, ball milling is performed for 4-5 hours, every 20-30 min of ball milling, 5-6 min of stopping and reversing.

[0014] Further, in step one, the mass ratio of graphite oxide, Co(NO3)2·6H2O and NiCl·6H2O is 50-60:110-120:40-50, the volume ratio of ultrapure water and triethanolamine is 12:1-4, and the ultrasonic treatment time is 30-40 min.

[0015] The mass ratio of graphite oxide, Co(NO3)2·6H2O and NiCl·6H2O is determined through experiments to ensure that the synthesized material has the required structure, composition and properties. If the ratio deviates from these ranges, the synthesized material cannot meet the design or specification requirements, and will have a negative effect on the experimental results. First, the reaction efficiency is reduced, and the proportion of reactants will affect the efficiency of the reaction to a certain extent, the reaction will be excessive or insufficient, resulting in low product yield or too many impurities. Second, instability or inconsistency, the proportion exceeding the specified range may cause instability or inconsistency of the material, which will adversely affect the preparation process and the performance of the material.

[0016] CoNi-CoO@rGO has two aspects of catalysis for MgH2, one is that the Schottky defects caused by Co-CoO promote the migration of H, thereby promoting the dissociation and absorption of H in MgH2, and the other is that Mg2Co-Mg2CoH5 and Mg2Ni-Mg2NiH4 coupling are formed in the hydrogen absorption and desorption cycle, which promotes the accelerated transfer of hydrogen.

[0017] Further, in step two, the heating is carried out in a reaction kettle, and the inner lining material of the reaction kettle is polytetrafluoroethylene, which is beneficial to the chemical reaction of various corrosive and viscous substances, avoids cross contamination, and at the same time, polytetrafluoroethylene can work at a relatively high temperature, ensuring the accuracy of the experiment.

[0018] Further, in step three, the washing is first carried out with ultrapure water, and then with anhydrous ethanol, so as to facilitate drying.

[0019] Further, in step five, the nitrogen flow of the nitrogen gas flow is controlled at 60-200sccm, the heating rate is 0.5-1℃ / min, the first holding time is 2-5h, and the second holding time is 4-6h. The cooling time is 18-24 hours.

[0020] The composite hydrogen storage material prepared by the preparation method of any one of claims 1-8 comprises MgH2 and CoNi-CoO@rGO, the metal Co and the oxide CoO can conveniently introduce the metal-semiconductor structure of Schottky, have uniform and abundant active sites, and the composite hydrogen storage material has a disordered stacked lamellar structure.

[0021] Further, the particle size of CoNi-CoO@rGO is 150-350nm, and the mass percentage of CoNi-CoO@rGO is 3-9wt%. rGO usually exists as a carrier or support material, and its main role is to provide specific surface area, enhance the dispersibility and stability of the catalyst.

[0022] Working principle: CoO in the CoNi-CoO@rGO catalyst and the alloy in the reaction process form Schottky defects, which provide more channels for the movement of hydrogen, thereby accelerating the hydrogen diffusion in the reaction process, and play an important role in improving the reaction kinetics.

[0023] Advantages: compared with the prior art, the present application has the following remarkable features:

[0024] 1. The preparation of CoNi-CoO@rGO is convenient and fast, and the preparation time is short, which is suitable for popularization and application.

[0025] 2、CoNi-CoO@rGO catalyst is uniformly distributed around the sub-micron MgH2 particles, has good catalytic effect, and forms Mg2Co-Mg2CoH5 and Mg2Ni-Mg2NiH4 coupling during the hydrogen absorption and release cycle, promotes the accelerated transfer of hydrogen, and significantly optimizes the hydrogen storage kinetics of MgH2;

[0026] 3、7wt% of CoNi-CoO@rGO catalyst after ball milling and compounding, the initial hydrogen release temperature of the sample is reduced to 195.5℃, and the sample can quickly release hydrogen at a constant temperature of 290℃, and 7.01wt% of hydrogen can be released in 30 minutes, and at the same time, 5.8wt% of hydrogen absorption amount can be obtained under the condition of 150℃ and 3.3MPa in 20 minutes, and the MgH2+7wt% CoNi-CoO@rGO composite hydrogen storage material has excellent hydrogen absorption performance, and has low initial hydrogen absorption temperature and good hydrogen absorption kinetics. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the XRD pattern of the CoNi-CoO@rGO catalyst obtained in Example 2 of the present application;

[0028] Figure 2 is the SEM pattern of the CoNi-CoO@rGO catalyst obtained in Example 2 of the present application;

[0029] Figure 3 is the temperature rising hydrogen release curve of the present application;

[0030] Figure 4 is the temperature rising hydrogen absorption curve of the present application;

[0031] Figure 5 is the temperature rising hydrogen release comparison curve of the present application;

[0032] Figure 6 is the temperature rising hydrogen absorption comparison curve of the present application;

[0033] Figure 7 is the temperature rising hydrogen release curve of Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0034] In the following examples, graphite oxide was purchased from (99.99% purity, Aladdin), Co(NO3)2·6H2O was purchased from (99.99% purity, Aladdin), NiCl·6H2O was purchased from (99.99% purity, Aladdin), and triethanolamine was purchased from (99.99% purity, Aladdin).

[0035] Graphite oxide (99.99% purity, Aladdin): Graphite oxide is commonly used as an electrical conductor or a support for catalysts. In many chemical reactions, graphite oxide can be used to provide a reaction surface, facilitating catalytic reactions or electrochemical processes. Its high purity helps to reduce factors that can lead to impurities, ensuring the stability and reproducibility of reactions or experiments.

[0036] Co(NO3)2·6H2O (99.99% purity, Aladdin): Cobalt nitrate is a cobalt-containing compound commonly used in the preparation of cobalt-based catalysts. It can be used as a precursor for catalysts in the synthesis or improvement of chemical reactions, especially those requiring cobalt ions. High-purity cobalt nitrate helps to ensure the quality stability of the prepared catalyst.

[0037] NiCl·6H2O (99.99% purity, Aladdin): Nickel chloride is a nickel-containing compound commonly used in the preparation of nickel catalysts. It can be used to synthesize or improve a variety of organic chemical reactions, especially those involving nickel catalysis. High-purity nickel chloride helps to ensure that the prepared catalyst has controllable performance.

[0038] Triethanolamine (99.99% purity, Aladdin): Triethanolamine is an organic compound commonly used as a base or neutralizing agent to adjust the pH value in reactions or experiments. It can also be used as a solvent, ligand for catalysts, or intermediate for the synthesis of organic compounds. High-purity triethanolamine helps to ensure that unnecessary impurities or reaction interference are avoided in the reaction.

[0039] Example 1

[0040] A method for preparing a composite hydrogen storage material, comprising the following steps:

[0041] (1) Add 30 mg of graphite oxide to 60 mL of ultrapure water and sonicate for 40 minutes. Dissolve 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O in it.

[0042] (2) After the dissolution is complete, add 20 mL of triethanolamine to the solution obtained in step (1), then transfer the solution to a polytetrafluoroethylene-lined reaction kettle, stir uniformly, and heat in an oven at 100°C for 12 hours.

[0043] (3) After the product of step (2) is cooled, centrifuge the resulting precipitate, wash it with ultrapure water 5 times, and finally wash it with anhydrous ethanol once to facilitate drying.

[0044] (4) Dry the product obtained in step (3) at 60°C for 7h.

[0045] (5) The product obtained in step (4) was placed in a tube furnace, and heated to 400°C at a rate of 1°C / min in a nitrogen flow of 100 sccm, once for 4 h, and then continuously heated to 500°C at a rate of 1°C / min, twice for 5 h, and cooled for 20 h to obtain CoNi-CoO@rGO.

[0046] (6) In a glove box, 91 wt% of MgH2 and 9 wt% of CoNi-CoO@rGO were added to a ball milling jar, followed by the addition of iron balls at a ball-to-material ratio of 40:1, a sealing ring was installed and the screw was tightened, and the ball milling jar was kept in an argon atmosphere at all times. The assembled ball milling jar was loaded on a planetary ball mill, and ball milled at a speed of 300 r / min for 5 h, with 30 min of ball milling, 5 min of stopping and reversing every 30 min.

[0047] The composite hydrogen storage material obtained in this example has a CoO with a Schottky structure, has uniform and abundant active sites, and has a disordered stacked sheet-like structure. The particle size of CoNi-CoO@rGO is 150-350 nm.

[0048] Example 2

[0049] A method for preparing a composite hydrogen storage material, comprising the following steps:

[0050] (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water, and ultrasonicated for 30 min, and 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein.

[0051] (2) After the dissolution was completed, 10 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated in an oven at 80°C for 12 h.

[0052] (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water 4 times, and finally washed with anhydrous ethanol once to facilitate drying.

[0053] (4) The product obtained in step (3) was dried at 60°C for 6 h.

[0054] (5) The product obtained in step (4) was placed in a tube furnace, and heated to 400°C at a rate of 1°C / min in a nitrogen flow of 100 sccm, once for 4 h, and then continuously heated to 500°C at a rate of 1°C / min, twice for 5 h, and cooled for 20 h to obtain CoNi-CoO@rGO.

[0055] As Figure 1The XRD spectrum of the prepared CoNi-CoO@rGO shows that the proportion of each component in the catalyst is 2.3wt% CoO and 97.7wt% CoNi alloy, indicating that the CoNi-CoO@rGO is successfully prepared.

[0056] (6) In the glove box, 97wt% MgH2 and 3wt% CoNi-CoO@rGO were added to the ball milling tank, followed by adding iron balls at a ball-to-material ratio of 40:1, sealing the ring and screwing the screw, so that the ball milling tank always maintains an argon atmosphere. The assembled ball milling tank was loaded on a planetary ball mill, and ball milling was carried out at a speed of 400r / min for 4 hours, with 30min of ball milling, 6min of stopping and reversing every 30min.

[0057] As Figure 2 The TEM image of CoNi-CoO@rGO shows that CoNi-CoO@rGO is composed of nanoparticles with a size of 150-350nm, maintaining the special layered structure of graphite oxide.

[0058] Example 3

[0059] A preparation method of a composite hydrogen storage material, comprising the following steps:

[0060] (1) 35mg of graphite oxide was added to 60mL of ultrapure water and ultrasonicated for 30min, and 4mmol of Co(NO3)2·6H2O and 2mmol of NiCl·6H2O were dissolved therein.

[0061] (2) After the dissolution was completed, 10mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated in an oven at 100℃ for 15 hours.

[0062] (3) After the product of step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water 4 times, and finally washed with anhydrous ethanol once to facilitate drying.

[0063] (4) The product of step (3) was dried at 60℃ for 8h.

[0064] (5) The product of step (4) was placed in a tube furnace, and heated to 300℃ at a rate of 1℃ / min under a nitrogen flow of 200sccm, and once-heat treated for 5h, then continued to heat to 500℃ at a rate of 1℃ / min, and twice-heat treated for 5h, and cooled for 24h to obtain CoNi-CoO@rGO.

[0065] (6) In the glove box, 93wt% of MgH2 and 7wt% of CoNi-CoO@rGO were added to the ball milling jar, followed by the addition of iron balls at a ball-to-powder ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was kept in an argon atmosphere at all times. The assembled ball milling jar was loaded on a planetary ball mill, and ball milling was performed at a speed of 400 r / min for 4.5 hours, with 25 minutes of ball milling, 5 minutes of stopping and reversing every 25 minutes.

[0066] The composite hydrogen storage material obtained in this example has a CoO with a Schottky structure, has uniform and abundant active sites, and has a disordered stacked sheet-like structure. The particle size of CoNi-CoO@rGO is 150-350 nm.

[0067] Example 4

[0068] A method for preparing a composite hydrogen storage material, comprising the following steps:

[0069] (1) 40 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 30 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved in the solution.

[0070] (2) After the dissolution was completed, 5 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 100°C in an oven for 15 hours.

[0071] (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water 5 times, and finally washed with anhydrous ethanol once to facilitate drying.

[0072] (4) The product obtained in step (3) was dried at 80°C for 6 hours.

[0073] (5) The product obtained in step (4) was placed in a tube furnace, and heated to 400°C at a rate of 1°C / min in a nitrogen flow of 150 sccm, and then heated to 500°C at a rate of 1°C / min, and then heated for 6 hours, and then cooled for 22 hours to obtain CoNi-CoO@rGO.

[0074] (6) In the glove box, 95wt% of MgH2 and 5wt% of CoNi-CoO@rGO were added to the ball milling jar, followed by the addition of iron balls at a ball-to-powder ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was kept in an argon atmosphere at all times. The assembled ball milling jar was loaded on a planetary ball mill, and ball milling was performed at a speed of 350 r / min for 4 hours, with 20 minutes of ball milling, 6 minutes of stopping and reversing every 20 minutes.

[0075] The composite hydrogen storage material obtained in the embodiment has a Schottky structure, has uniform and rich active sites, and has a disordered stacked sheet structure. The particle size of the CoNi-CoO@rGO is 150-350 nm.

[0076] Example 5

[0077] A preparation method of a composite hydrogen storage material, comprising the following steps:

[0078] (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water, and ultrasonic was performed for 35 minutes. 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved in the solution.

[0079] (2) After the dissolution was completed, 15 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle. After being stirred uniformly, the solution was heated in a drying oven at 90°C for 14 hours.

[0080] (3) After the obtained product in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water for 4 times, and finally washed with anhydrous ethanol once to facilitate drying.

[0081] (4) The obtained product in step (3) was dried at 70°C for 7h.

[0082] (5) The obtained product in step (4) was placed in a tube furnace, and was heated to 350°C at a rate of 0.5°C / min in a nitrogen flow of 120 sccm. Once the temperature was maintained for 4h, then the temperature was continuously increased to 550°C at a rate of 0.5°C / min. Twice the temperature was maintained for 6h. After being cooled for 23 hours, CoNi-CoO@rGO was obtained.

[0083] (6) In a glove box, 96wt% of MgH2 and 4wt% of CoNi-CoO@rGO were added to a ball milling tank, and then iron balls were added according to a ball-to-material ratio of 40:1. A sealing ring was installed and the screw was tightened, so that the ball milling tank was always maintained in an argon atmosphere. The assembled ball milling tank was loaded on a planetary ball mill, and was ball milled at a speed of 300r / min for 5 hours. Every 25 minutes of ball milling, the rotation was stopped for 5 minutes and the direction was reversed.

[0084] The composite hydrogen storage material obtained in the embodiment has a Schottky structure, has uniform and rich active sites, and has a disordered stacked sheet structure. The particle size of the CoNi-CoO@rGO is 150-350 nm.

[0085] Example 6

[0086] The remaining steps of this example are the same as those of Example 2, with the only difference being that in step (6), 93 wt% of MgH2and 7 wt% of CoNi-CoO@rGO are added to the ball mill tank inside the glove box.

[0087] In the glove box, 150 mg of the composite hydrogen storage material sample is placed into the hydrogen storage tester reactor, the vacuum pump is turned on for evacuation, and then the reactor is tested for air tightness. Hydrogen is introduced at 32-33 bar, and the test is started. The temperature is raised at a rate of 1°C / min to 350°C. The temperature rise hydrogen desorption and absorption properties of MgH2+7 wt% CoNi-CoO@rGO composite material and MgH2are determined.

[0088] In the glove box, 150 mg of the composite hydrogen storage material sample is placed into the hydrogen storage tester reactor, the vacuum pump is turned on for evacuation, and then the reactor is tested for air tightness. Hydrogen is introduced at 32-33 bar, and the test is started. The temperature is raised at a rate of 1°C / min to 350°C. The temperature rise hydrogen desorption and absorption properties of MgH2+7 wt% CoNi-CoO@rGO composite material and MgH2are determined.

[0089] The "constant volume-pressure difference method" is used to test the effect of CoNi-CoO@rGO on the temperature rise hydrogen desorption (absorption) properties of MgH2. The hydrogen desorption and absorption properties of MgH2+7 wt% CoNi-CoO@rGO composite material and MgH2are determined by Figures 3-4 It can be seen that after the addition of CoNi-CoO@rGO, the initial hydrogen desorption temperature of MgH2+7 wt% CoNi-CoO@rGO composite material is reduced to 190°C, the initial hydrogen desorption temperature is significantly reduced, and the hydrogen desorption rate is increased. In the hydrogen absorption process, the initial hydrogen absorption temperature of MgH2+7 wt% CoNi-CoO@rGO composite material is significantly advanced, hydrogen absorption starts at room temperature, and the end temperature of hydrogen absorption is also significantly reduced. The hydrogen absorption and desorption kinetics of MgH2are greatly improved.

[0090] Comparative Example 1

[0091] MgH2and CoNi are physically mixed to prepare a composite material containing 7 wt% NiCo.

[0092] In the same way as in Example 6, 70 mg of NiCo (physically mixed) prepared in Comparative Example 1 and 930 mg of MgH2are placed into an argon-filled ball mill tank, and then ball milled in a ball mill for 6 hours to obtain a uniformly mixed MgH2+7 wt% NiCo composite hydrogen storage material. The MgH2+7 wt% NiCo composite hydrogen storage material is then placed into a hydrogen storage tester reactor for testing of the temperature rise hydrogen desorption and absorption properties.

[0093] The "constant volume-pressure difference method" is used to test the effect of the heterostructure in Ni / V2O3 on the temperature rise hydrogen desorption (absorption) properties of MgH2. The hydrogen desorption and absorption properties of MgH2+7 wt% Ni / V2O3 composite material and MgH2are determined by Figures 5-6It can be seen that the initial dehydrogenation temperature of MgH2 added with CoNi-CoO@rGO is obviously lower than that of MgH2 added with NiCo, and the dehydrogenation rate is also faster than that of MgH2 added with NiCo; and in the hydrogen absorption process, the initial hydrogen absorption temperature of MgH2 added with CoNi-CoO@rGO is also lower than that of MgH2 added with NiCo. The above results show that CoNi-CoO@rGO with Schottky structure has a better catalytic effect on MgH2, and the Schottky structure in the prepared CoNi-CoO@rGO can provide more active sites and catalytic centers, and better improve the hydrogen absorption and desorption kinetics of MgH2.

[0094] Example 7

[0095] The remaining steps of this example are the same as those of Example 2, and the only difference is that in step (6), 95wt% of MgH2 and 5wt% of CoNi-CoO@rGO are added to the ball mill tank in the glove box.

[0096] Example 8

[0097] The remaining steps of this example are the same as those of Example 2, and the only difference is that in step (6), 91wt% of MgH2 and 9wt% of CoNi-CoO@rGO are added to the ball mill tank in the glove box.

[0098] The temperature rising dehydrogenation performance is tested by the same method as in Example 6, and it is found that: Figure 7 , the initial dehydrogenation temperature of MgH2+7wt% CoNi-CoO@rGO is lower than that of MgH2+5wt% CoNi-CoO@rGO, and it has better hydrogen storage performance, and MgH2+9wt% CoNi-CoO@rGO has similar hydrogen storage performance to MgH2+7wt% CoNi-CoO@rGO, and the dehydrogenation amount is greatly reduced, therefore, MgH2+7wt% CoNi-CoO@rGO is the best ratio, i.e. Example 6 is the best embodiment.

[0099] Comparative Example 2

[0100] The remaining steps of this comparative example are the same as those of Example 6, and the only difference is that in step (1), Co(NO3)2·6H2O is 5mmol and NiCl·6H2O is 3mmol. The prepared CoNi-CoO@rGO nanocatalyst is mixed with MgH2 material by ball milling at a doping ratio of 7wt%, to obtain a uniformly mixed composite hydrogen storage material. The temperature rising dehydrogenation performance is detected, and it is found that when too much Ni is added, it will interact with Co to affect the generation of Schottky defects of Co-CoO. The hydrogen storage performance of MgH2+7wt% CoNi-CoO@rGO prepared in Example 6 is better than that of MgH2+7wt% CoNi-CoO@rGO prepared in this comparative example.

[0101] Comparative Example 3

[0102] The comparative example is identical to the remaining steps of Example 6, except that in step (1), Co(NO3)2·6H2O is 3 mmol and NiCl·6H2O is 1 mmol. The prepared CoNi-CoO@rGO nanocatalyst is mixed with MgH2 material by ball milling at a doping ratio of 7 wt%, to obtain a uniformly mixed composite hydrogen storage material. The temperature rising hydrogen desorption performance of the composite hydrogen storage material is detected, and it is found that when the amount of Ni added is too small, the coupling of Mg2Ni-Mg2NiH4 is affected, and the catalytic performance is weakened. The hydrogen storage performance of MgH2+7wt%CoNi-CoO@rGO prepared in Example 6 is better than that of MgH2+7wt%CoNi-CoO@rGO prepared in the comparative example, indicating that the CoNi-CoO@rGO in Example 6 has better catalytic effect.

Claims

1. A method for preparing a composite hydrogen storage material, characterized by, Comprising the following steps: (1) 30 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 40 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 20 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 100°C in a drying oven for 12 hours; (3) After the product obtained in step (2) was cooled, the precipitate was centrifuged, washed with ultrapure water 5 times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 60°C for 7h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 400°C at a rate of 1°C / min under a nitrogen flow of 100 sccm, once for 4h, and then continued to heat to 500°C at a rate of 1°C / min, twice for 5h, and cooled for 20h to obtain CoNi-CoO@rGO; (6) In a glove box, 91wt% of MgH2 and 9wt% of CoNi-CoO@rGO were added to a ball milling jar, followed by the addition of iron balls at a ball-to-material ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was always kept in an argon atmosphere, and the assembled ball milling jar was loaded on a planetary ball mill at a speed of 300 r / min for 5 hours, with 30 minutes of ball milling, 5 minutes of stopping and reversing every 30 minutes.

2. A method for preparing a composite hydrogen storage material, characterized by, Comprising the following steps: (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 30 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 10 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 80°C in a drying oven for 12 hours; (3) After the product obtained in step (2) was cooled, the precipitate was centrifuged, washed with ultrapure water 4 times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 60°C for 6h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 300°C at a rate of 1°C / min under a nitrogen flow of 60 sccm, once for 2h, and then continued to heat to 500°C at a rate of 1°C / min, twice for 4h, and cooled for 18h to obtain CoNi-CoO@rGO; (6) In a glove box, 97wt% of MgH2 and 3wt% of CoNi-CoO@rGO were added to a ball milling jar, followed by the addition of iron balls at a ball-to-material ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was always kept in an argon atmosphere, and the assembled ball milling jar was loaded on a planetary ball mill at a speed of 400 r / min for 4 hours, with 30 minutes of ball milling, 6 minutes of stopping and reversing every 30 minutes.

3. A method for preparing a composite hydrogen storage material, characterized by, Comprising the following steps: (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 30 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 10 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 100°C in a drying oven for 15 hours; (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water 4 times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 60°C for 8h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 300°C at a rate of 1°C / min under a nitrogen flow of 200 sccm, once for 5h, then continued to heat to 500°C at a rate of 1°C / min, twice for 5h, and cooled for 24 hours to obtain CoNi-CoO@rGO; (6) In a glove box, 93wt% of MgH2 and 7wt% of CoNi-CoO@rGO were added to a ball mill jar, then iron balls were added at a ball-to-material ratio of 40:1, a sealing ring was installed and the screw was tightened, and the ball mill jar was always kept in an argon atmosphere, and the assembled ball mill jar was loaded on a planetary ball mill at a speed of 400 r / min, and ball milled for 4.5 hours, with 25 minutes of ball milling, 5 minutes of stopping and reversing every 25 minutes.

4. A method for preparing a composite hydrogen storage material, characterized by, including the following steps: (1) 40 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 30 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 5 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 100°C in a drying oven for 15 hours; (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water 5 times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 80°C for 6h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 400°C at a rate of 1°C / min under a nitrogen flow of 150 sccm, once for 3h, then continued to heat to 500°C at a rate of 1°C / min, twice for 6h, and cooled for 22 hours to obtain CoNi-CoO@rGO; (6) In a glove box, 95wt% of MgH2 and 5wt% of CoNi-CoO@rGO were added to a ball mill jar, then iron balls were added at a ball-to-material ratio of 40:1, a sealing ring was installed and the screw was tightened, and the ball mill jar was always kept in an argon atmosphere, and the assembled ball mill jar was loaded on a planetary ball mill at a speed of 350 r / min, and ball milled for 4 hours, with 20 minutes of ball milling, 6 minutes of stopping and reversing every 20 minutes.

5. A method for preparing a composite hydrogen storage material, characterized by, including the following steps: (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 35 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 15 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 90°C in a drying oven for 14 hours; (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water four times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 70°C for 7h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 350°C at a rate of 0.5°C / min under a nitrogen flow of 120 sccm, once for 4h, and then continued to heat to 550°C at a rate of 0.5°C / min, twice for 6h, and cooled for 23h to obtain CoNi-CoO@rGO; (6) In a glove box, 96wt% of MgH2 and 4wt% of CoNi-CoO@rGO were added to a ball milling jar, followed by the addition of iron balls at a ball-to-material ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was always kept in an argon atmosphere, and the assembled ball milling jar was loaded on a planetary ball mill at a speed of 300 r / min, and ball milled for 5 hours, every 25 minutes of ball milling, stop for 5 minutes and reverse.

6. A method for preparing a composite hydrogen storage material, characterized by, including the following steps: (1) 35 mg of graphite oxide was added to 60 mL of ultrapure water and ultrasonicated for 35 minutes, 4 mmol of Co(NO3)2·6H2O and 2 mmol of NiCl·6H2O were dissolved therein; (2) After the dissolution was completed, 15 mL of triethanolamine was added to the solution obtained in step (1), and then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, stirred uniformly, and heated at 90°C in a drying oven for 14 hours; (3) After the product obtained in step (2) was cooled, the obtained precipitate was centrifuged, washed with ultrapure water four times, and finally washed with anhydrous ethanol once to facilitate drying; (4) The product obtained in step (3) was dried at 70°C for 7h; (5) The product obtained in step (4) was placed in a tube furnace, heated to 350°C at a rate of 0.5°C / min under a nitrogen flow of 120 sccm, once for 4h, and then continued to heat to 550°C at a rate of 0.5°C / min, twice for 6h, and cooled for 23h to obtain CoNi-CoO@rGO; (6) In a glove box, 96wt% of MgH2 and 4wt% of CoNi-CoO@rGO were added to a ball milling jar, followed by the addition of iron balls at a ball-to-material ratio of 40:1, the sealing ring was installed and the screw was tightened, and the ball milling jar was always kept in an argon atmosphere, and the assembled ball milling jar was loaded on a planetary ball mill at a speed of 300 r / min, and ball milled for 5 hours, every 25 minutes of ball milling, stop for 5 minutes and reverse.

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