阅读说明：本技术 复合储氢材料及其制备方法 (Composite hydrogen storage material and preparation method thereof ) 是由 李松 刘成宝 陈浩 夏潇潇 于 2021-09-06 设计创作，主要内容包括：本发明涉及复合储氢材料的技术领域,特别涉及一种复合储氢材料及其制备方法。所述复合储氢材料的材质为金属有机骨架和氧化石墨烯的复合载体与可溶性锂盐的复合物。本发明的复合储氢材料能够解决金属有机骨架在室温条件下氢气吸附量低的问题。(The invention relates to the technical field of composite hydrogen storage materials, in particular to a composite hydrogen storage material and a preparation method thereof. The composite hydrogen storage material is made of a composite of a metal organic framework, a composite carrier of graphene oxide and a soluble lithium salt. The composite hydrogen storage material can solve the problem that the metal organic framework has low hydrogen adsorption capacity at room temperature.)

1. The composite hydrogen storage material is characterized in that the composite hydrogen storage material is a composite of a composite carrier of a metal organic framework and graphene oxide and a soluble lithium salt.

2. The composite hydrogen storage material according to claim 1, wherein the ratio of the amount of the substance of the soluble lithium salt to the mass of the composite support of the metal-organic framework and graphene oxide is (0.0005-0.005) mol: 1g of the total weight of the composition.

3. The composite hydrogen storage material of claim 1 or 2, wherein in the composite support of the metal-organic framework and the graphene oxide, the metal-organic framework is one or more of MIL-100(Fe), MIL-101(Cr), HKUST-1, MOF-5, MIL-53, UiO-66 and DUT-67.

4. A composite hydrogen storage material according to claim 1 or 2, characterized in that the soluble lithium salt is one or several of lithium chloride, lithium nitrate and lithium sulphate.

5. A method of making a composite hydrogen storage material according to any one of claims 1 to 4, comprising the steps of:

preparing a composite carrier of a metal organic framework and graphene oxide;

and (3) soaking the composite carrier of the metal organic framework and the graphene oxide in a soluble lithium salt solution, and collecting a solid after stirring.

6. The method of claim 5, wherein the solvent of the soluble lithium salt solution is ethanol, methanol, acetone, acetonitrile or dichloromethane.

7. The method for preparing a composite hydrogen storage material according to claim 5, wherein the metal-organic framework is MIL-100(Fe), and the method for preparing the composite support of the metal-organic framework and the graphene oxide comprises the following steps:

mixing trimesic acid, an alkaline substance and water to prepare a first solution;

mixing graphene oxide, soluble iron salt and water to prepare a second solution;

adding the first solution into the second solution, and collecting a solid after stirring.

8. The method of claim 7, wherein the molar ratio of trimesic acid, alkaline substance and soluble iron salt is 2:6: 3.

9. The method for preparing a composite hydrogen storage material according to claim 8, wherein the graphene oxide accounts for 2-20% of the soluble iron salt by mass.

10. The method of preparing a composite hydrogen storage material of claim 7, wherein the alkaline substance is sodium hydroxide; and/or

The soluble ferric salt is ferrous chloride tetrahydrate.

Technical Field

The invention relates to the technical field of composite hydrogen storage materials, in particular to a composite hydrogen storage material and a preparation method thereof.

Background

The hydrogen is a clean and pollution-free green energy, can assist the realization of the aims of carbon peak reaching and carbon neutralization, and has attracted much attention in recent years.

Metal Organic Frameworks (MOFs) are considered to be promising hydrogen storage adsorbents due to their advantages of high specific surface area, adjustable pore volume and adjustable structure. However, since the interaction between MOFs and hydrogen is mainly van der waals force, the interaction is weak, and a high hydrogen adsorption amount can be obtained only at a low temperature, and the hydrogen adsorption amount is extremely low at room temperature.

Disclosure of Invention

Based on the above, the invention provides a composite hydrogen storage material, which solves the problem that the metal organic framework has low hydrogen adsorption capacity at room temperature.

In order to solve the problems, the technical scheme of the invention is as follows:

the composite hydrogen storage material is prepared from a composite carrier of a metal organic framework and graphene oxide and a soluble lithium salt.

In one embodiment, the ratio of the amount of the soluble lithium salt to the mass of the composite support of the metal-organic framework and graphene oxide is (0.0005 to 0.005) mol: 1g of the total weight of the composition.

In one embodiment, in the composite carrier of the metal organic framework and the graphene oxide, the metal organic framework is one or more of MIL-100(Fe), MIL-101(Cr), HKUST-1, MOF-5, MIL-53, UiO-66 and DUT-67.

In one embodiment, the soluble lithium salt is one or more of lithium chloride, lithium nitrate, and lithium sulfate.

The invention also provides a preparation method of the composite hydrogen storage material.

The preparation method of the composite hydrogen storage material comprises the following steps:

preparing a composite carrier of a metal organic framework and graphene oxide;

and (3) soaking the composite carrier of the metal organic framework and the graphene oxide in a soluble lithium salt solution, and collecting a solid after stirring.

In one embodiment, the solvent of the soluble lithium salt solution is ethanol, methanol, acetone, acetonitrile, or dichloromethane.

In one embodiment, the metal-organic framework is MIL-100(Fe), and the preparation method of the composite support of the metal-organic framework and graphene oxide comprises the following steps:

mixing trimesic acid, an alkaline substance and water to prepare a first solution;

mixing graphene oxide, soluble iron salt and water to prepare a second solution;

adding the first solution into the second solution, and collecting a solid after stirring.

In one embodiment, the molar ratio of trimesic acid, alkaline material and soluble iron salt is 2:6: 3.

In one embodiment, the graphene oxide accounts for 2-20% of the soluble iron salt by mass.

In one embodiment, the alkaline material is sodium hydroxide.

In one embodiment, the soluble iron salt is ferrous chloride tetrahydrate.

Compared with the traditional scheme, the invention has the following beneficial effects:

the composite hydrogen storage material is a composite of a composite carrier of a metal organic framework and Graphene Oxide (GO) and a soluble lithium salt. The graphene oxide is a graphene-like structure which is obtained by oxidizing graphite and is rich in oxygen-containing functional groups, has high atomic density and can provide high dispersion force, and has the effect of improving the hydrogen adsorption capacity after the graphene oxide is compounded with a metal organic framework.

In addition, when the composite hydrogen storage material is prepared, the composite carrier of the metal organic framework and the graphene oxide is prepared, and then the soluble lithium salt is compounded, so that lithium ions are uniformly dispersed on the composite carrier, the addition of the soluble lithium salt is easy to control, the doping amount of lithium in the composite hydrogen storage material is easy to control, and the experimental controllability is improved. In addition, the preparation method of the composite hydrogen storage material does not need heating or corrosive acid assistance such as hydrofluoric acid, has the advantages of simple process, energy conservation, environmental protection, high safety and low cost, and has great potential for industrial large-scale preparation.

Drawings

FIG. 1 is an XRD pattern of composite hydrogen storage materials prepared in examples 1-3 and comparative example 1;

FIG. 2 is an SEM image of composite hydrogen storage materials prepared in examples 1-3 and comparative example 1;

FIG. 3 is a hydrogen sorption capacity isotherm of the composite hydrogen storage material 298K prepared in examples 1-3 and comparative example 1;

FIG. 4 is an XRD pattern of the composite hydrogen storage material prepared in comparative example 2;

FIG. 5 is an SEM image of a composite hydrogen storage material prepared in comparative example 2;

FIG. 6 is a hydrogen sorption capacity isotherm of the composite hydrogen storage material 298K prepared in comparative example 2.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Term(s) for

Unless otherwise stated or contradicted, terms or phrases used herein have the following meanings:

as used herein, the term "and/or", "and/or" includes any one of two or more of the associated listed items, as well as any and all combinations of the associated listed items, including any two of the associated listed items, any more of the associated listed items, or all combinations of the associated listed items.

As used herein, "one or more" means any one, any two, or any two or more of the listed items. Wherein, the 'several' means any two or more than any two.

As used herein, "a combination thereof," "any combination thereof," and the like, includes all suitable combinations of any two or more of the listed items.

In the present specification, the term "suitable" in "a suitable combination, a suitable manner," any suitable manner "and the like shall be construed to mean that the technical solution of the present invention can be implemented, the technical problem of the present invention can be solved, and the technical effect of the present invention can be achieved.

Herein, "preferred" merely describes a more effective embodiment or example, and it should be understood that the scope of the present invention is not limited thereto.

In the present invention, the technical features described in the open type include a closed technical solution composed of the listed features, and also include an open technical solution including the listed features.

In the present invention, the numerical range is defined to include both end points of the numerical range unless otherwise specified.

The percentage contents referred to in the present invention mean, unless otherwise specified, mass percentages for solid-liquid mixing and solid-solid phase mixing, and volume percentages for liquid-liquid phase mixing.

The percentage concentrations referred to in the present invention refer to the final concentrations unless otherwise specified. The final concentration refers to the ratio of the additive component in the system to which the component is added.

The temperature parameter in the present invention is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.

In the present invention, unless otherwise specified, "room temperature" means 25 ℃ and 298K, and also means a temperature which fluctuates within a certain similar temperature range.

The hydrogen is a clean and pollution-free green energy, can assist the realization of the aims of carbon peak reaching and carbon neutralization, and has attracted much attention in recent years.

Metal Organic Frameworks (MOFs) are considered to be promising hydrogen storage adsorbents due to their advantages of high specific surface area, adjustable pore volume and adjustable structure. However, since the interaction between MOFs and hydrogen is mainly van der waals force, the interaction is weak, and a high hydrogen adsorption amount can be obtained only at a low temperature, and the hydrogen adsorption amount is extremely low at room temperature.

Based on the above, the invention provides a composite hydrogen storage material, which solves the problem that the metal organic framework has low hydrogen adsorption capacity at room temperature.

The technical scheme is as follows:

the composite hydrogen storage material is prepared from a composite carrier of a metal organic framework and graphene oxide and a soluble lithium salt.

On the basis of a metal organic framework, graphene oxide is added, the graphene oxide is a graphene-like structure which is formed by oxidizing graphite and is rich in oxygen-containing functional groups, has high atomic density and can provide high dispersion force, and after the graphene oxide is compounded with the metal organic framework, the hydrogen adsorption capacity is improved. The graphene oxide can be a graphene oxide suspension prepared by a reference Hummers method or an improved method.

On the basis of the composite carrier, soluble lithium salt is further added, so that the interaction between the composite hydrogen storage material and hydrogen molecules is enhanced, and the hydrogen adsorption capacity of the composite hydrogen storage material at room temperature (298K) can be effectively improved.

Alternatively, the ratio of the amount of the soluble lithium salt to the mass of the composite support of the metal-organic framework and graphene oxide is (0.0005 to 0.005) mol: 1g of the total weight of the composition.

In one embodiment, the preparation method of the composite hydrogen storage material comprises the following steps:

preparing a composite carrier of a metal organic framework and graphene oxide;

and (3) soaking the composite carrier of the metal organic framework and the graphene oxide in a soluble lithium salt solution, and collecting a solid after stirring.

The composite carrier of the metal organic framework and the graphene oxide can be prepared by an in-situ composite method, and the graphene oxide suspension can be added into a precursor solution for synthesizing the metal organic framework.

It will be appreciated that the stirring time may be from 4h to 12 h. In one embodiment, the stirring time is 8h and the stirring temperature is room temperature.

According to the invention, when the composite hydrogen storage material is prepared, the composite carrier of the metal organic framework and the graphene oxide is prepared, and then the soluble lithium salt is compounded, during compounding, the composite carrier of the metal organic framework and the graphene oxide is soaked in the soluble lithium salt solution, after the composite carrier is contacted for a period of time, lithium ions in the soluble lithium salt can be attached to the composite carrier of the metal organic framework and the graphene oxide, and the impregnation method is favorable for uniformly dispersing the lithium ions on the composite carrier, the addition amount of the soluble lithium salt is easy to control, the doping amount of lithium in the composite hydrogen storage material is easy to control, and the experimental controllability is improved. In addition, the preparation method of the composite hydrogen storage material does not need heating or corrosive acid assistance such as hydrofluoric acid, has the advantages of simple process, energy conservation, environmental protection, high safety and low cost, and has great potential for industrial large-scale preparation.

In one embodiment, the composite support of the metal-organic framework and the graphene oxide may be dispersed in a solvent to obtain a composite support dispersion solution of the metal-organic framework and the graphene oxide. Then soaking in soluble lithium salt solution, stirring and collecting solid.

Optionally, in the composite carrier dispersion solution of the metal organic framework and the graphene oxide, the mass-to-volume ratio of the composite carrier of the metal organic framework and the graphene oxide to the solvent is 0.5-3 g: 100 mL. In one embodiment, the mass-to-volume ratio of the composite carrier of the metal organic framework and the graphene oxide to the solvent is 1 g: 100 mL.

It is understood that the solvent is a general organic solvent capable of activating the metal-organic framework material, but it is required that the metal-organic framework structure is not broken, and the solvent has a low boiling point so as to be evaporated later. Alternatively, the solvent includes, but is not limited to, ethanol, methanol, acetone, acetonitrile, or dichloromethane.

The composite carrier of the metal organic framework and the graphene oxide is soaked in the soluble lithium salt solution, and the soluble lithium salt solution can be dropwise added into the composite carrier dispersion solution of the metal organic framework and the graphene oxide. Soaking the composite carrier of the metal organic framework and the graphene oxide in a soluble lithium salt solution, and after the composite carrier is contacted for a period of time, lithium ions in the soluble lithium salt can be attached to the composite carrier of the metal organic framework and the graphene oxide.

Alternatively, the soluble lithium salt solution is formulated by dissolving a soluble lithium salt in a solvent.

Optionally, the concentration of the soluble lithium salt in the soluble lithium salt solution is 0.5-3 mol/L. In one embodiment, the concentration of the soluble lithium salt is 1 mol/L.

Alternatively, the solvent of the soluble lithium salt solution includes, but is not limited to, ethanol, methanol, acetone, acetonitrile, or dichloromethane.

Optionally, the metal organic framework is one or more of MIL-100(Fe), MIL-101(Cr), HKUST-1, MOF-5, MIL-53, UiO-66 and DUT-67.

Optionally, the soluble lithium salt is one or more of lithium chloride, lithium nitrate, and lithium sulfate.

The solubility of lithium chloride in ethanol at room temperature was 25.0 g.

It will be appreciated that after agitation, the solids are collected by centrifugation, and the collected solids may be washed and finally dried. The rotation speed and time of centrifugation can be 6000rpm and 5min, respectively.

Alternatively, the washing may be by alternating washing with ultrapure water and anhydrous ethanol.

Alternatively, drying may be carried out at elevated temperature, for example 80 ℃. The drying time may be 8 h.

Preferably, the metal organic framework is MIL-100(Fe), the soluble lithium salt is lithium chloride, and the two are compounded with graphene oxide to form lithium-doped MIL-100 (Fe)/graphene oxide, which has excellent hydrogen adsorption capacity at room temperature.

In one embodiment, the metal organic framework is MIL-100(Fe), and MIL-100(Fe) can be obtained by taking trimesic acid and soluble iron salt as main reactants and stirring at room temperature. The MIL-100(Fe) and graphene oxide composite carrier can be obtained by taking trimesic acid, soluble ferric salt and graphene oxide as main reactants and stirring at room temperature. In one embodiment, the preparation method of the composite carrier of MIL-100(Fe) and graphene oxide comprises the following steps:

mixing trimesic acid, an alkaline substance and water to prepare a first solution;

mixing graphene oxide, soluble iron salt and water to prepare a second solution;

adding the first solution into the second solution, and collecting a solid after stirring.

It will be appreciated that the water used may be ultra pure water.

In one embodiment, the first solution is prepared by mixing trimesic acid with an aqueous solution of an alkaline substance and stirring for 10 min. The concentration of the aqueous solution of the basic substance may be 1 mol/L.

In one embodiment, the first solution is prepared by mixing graphene oxide and water, and then performing ultrasonic treatment for 15min, adding the soluble iron salt, and stirring until the soluble iron salt is completely dissolved, wherein the stirring time can be 10 min.

Optionally, the molar ratio of trimesic acid, alkaline substance and soluble iron salt is 2:6: 3.

Optionally, the mass of the graphene oxide accounts for 2% to 20% of the mass of the soluble iron salt, and more preferably, the mass of the graphene oxide accounts for 1% to 10% of the mass of the soluble iron salt. In one embodiment, the mass of the graphene oxide is 5% of the mass of the soluble iron salt.

Optionally, the alkaline substance is sodium hydroxide.

Optionally, the soluble iron salt is ferrous chloride tetrahydrate.

It will be appreciated that the first solution is added to the second solution and the stirring time may be 12-48 h. In one embodiment, the stirring time is 24h and the stirring temperature is room temperature.

It is to be understood that, when the first solution is added to the second solution, the first solution is added dropwise.

It will be appreciated that after agitation, the solids are collected by centrifugation, and the collected solids may be washed and finally dried. The rotation speed and time of centrifugation can be 6000rpm and 5min, respectively.

Alternatively, the washing may be by alternating washing with ultrapure water and anhydrous ethanol.

Alternatively, drying may be carried out at elevated temperature, for example 80 ℃. The drying time may be 8 h.

In the following, the raw materials referred to in the following specific examples are commercially available, unless otherwise specified, the equipment used, and the processes referred to, unless otherwise specified, are all routinely selected by those skilled in the art.

The preparation method of the graphene oxide suspension refers to a Hummers method, and is slightly modified as follows:

first, 23ml of concentrated sulfuric acid was measured and placed in an ice bath environment for 1 hour so that the temperature was lowered to about 4 ℃. Then, 1g of graphite powder and 0.5g of sodium nitrate were slowly added to the concentrated sulfuric acid, and cooling was continued for 1 hour. Then, potassium permanganate was slowly added thereto while controlling the temperature below 20 ℃ during the addition. After the potassium permanganate is added, the reaction is kept for about 30min when the temperature of the mixture rises to about 35 ℃. The ice bath was then removed and 46ml of deionized water was slowly added and the temperature was raised to around 98 ℃ and the solution turned brown in color and the reaction was allowed to stand under these conditions for 15 min. Next, 140ml of deionized water was added to dilute the solution, and 15ml of 30% hydrogen peroxide solution was added to terminate the reaction, and the solution became pale yellow. After 15min of reaction, 40ml of 10% hydrochloric acid were added. Then, the mixture is centrifuged at low speed for several times to remove excess acid and by-products. And finally, dispersing the washed approximately neutral graphite oxide in 320ml of deionized water, performing ultrasonic dispersion for 40min, and performing low-speed centrifugation at 2500rpm for 30min to obtain GO suspension as upper-layer liquid.

Example 1

The embodiment provides a composite hydrogen storage material and a preparation method thereof, and the preparation method comprises the following steps:

(1) 3.352g (15.2mmol) of trimesic acid was dissolved in 45.6mL of a 1mol/L aqueous solution of NaOH45.6mmol and stirred at room temperature for 10min until completely dissolved, and the resulting solution was designated as a first solution.

(2) 0.226g of the graphene oxide suspension was added to 194.4g of ultrapure water, followed by ultrasonic treatment for 15 min. Then 4.52g (22.8mmol) of ferrous chloride tetrahydrate was added to the above solution, and stirred at room temperature for 10min until completely dissolved, and the resulting solution was designated as a second solution.

(3) And (3) placing the second solution on a magnetic stirrer for stirring, dropwise adding the first solution into the second solution, starting timing when the dropwise adding is finished, and stirring at room temperature for 24 hours. And after stirring, centrifuging the suspension at 6000rpm for 5min to realize solid-liquid separation, sequentially washing the centrifuged product with ultrapure water and absolute ethyl alcohol for three times, and drying the obtained product at 80 ℃ for 8h to obtain the MIL-100(Fe)/GO composite carrier.

(4) 1g of dry MIL-100(Fe)/GO composite carrier is taken and dispersed into 100ml of absolute ethyl alcohol. Then, 0.5mL of a 1mol/L lithium chloride solution in ethanol was slowly added dropwise thereto, and stirred at room temperature for 8 hours. And finally, drying the centrifuged product at 80 ℃ for 8h to obtain the lithium ion doped metal organic framework/graphene oxide composite hydrogen storage material.

Powder X-ray diffraction of the composite hydrogen storage material prepared in this example was performed on an Empyrean model X-ray diffractometer manufactured by parnacho, the netherlands, with an operating voltage and an operating current of 40kV and 40mA, respectively, and a scanning range of 2 θ of 3 ° to 15 °, as shown in fig. 1.

The SEM image of the composite hydrogen storage material prepared in this example was obtained on a Nova Nano SEM 450 model field emission scanning electron microscope manufactured by FEI of the Netherlands, and the acceleration voltage tested was 15kV, and the result is shown in FIG. 2.

The room temperature hydrogen storage performance test of the composite hydrogen storage material prepared in this example was carried out on a BELSORP-HP type high pressure gas adsorption apparatus manufactured by Mickelbert corporation of Japan (MicrotracBEL), and the sample was vacuum-pretreated at 150 ℃ for 12 hours before the test, with the results shown in FIG. 3.

Example 2

The present embodiment provides a composite hydrogen storage material and a preparation method thereof, and the main differences from embodiment 1 are as follows: the adding amount of lithium chloride is different, and the steps are as follows:

(1) 3.352g of trimesic acid was dissolved in 45.6mL of a 1mol/L NaOH aqueous solution, and the solution was stirred at room temperature for 10min until complete dissolution, and the resulting solution was designated as a first solution.

(2) 0.226g of the graphene oxide suspension was added to 194.4g of ultrapure water, followed by ultrasonic treatment for 15 min. Then 4.52g of ferrous chloride tetrahydrate was added to the above solution and stirred at room temperature for 10min to be completely dissolved, and the resulting solution was designated as a second solution.

(3) And (3) placing the second solution on a magnetic stirrer for stirring, dropwise adding the first solution into the second solution, starting timing when the dropwise adding is finished, and stirring at room temperature for 24 hours. And after stirring, centrifuging the suspension at 6000rpm for 5min to realize solid-liquid separation, sequentially washing the centrifuged product with ultrapure water and absolute ethyl alcohol for three times, and drying the obtained product at 80 ℃ for 8h to obtain the MIL-100(Fe)/GO composite carrier.

(4) 1g of dry MIL-100(Fe)/GO composite carrier is taken and dispersed into 100ml of absolute ethyl alcohol. Then, 1mL of a 1mol/L lithium chloride ethanol solution was slowly added dropwise thereto, and stirred at room temperature for 8 hours. And finally, drying the centrifuged product at 80 ℃ for 8h to obtain the lithium ion doped metal organic framework/graphene oxide composite hydrogen storage material.

Powder X-ray diffraction of the composite hydrogen storage material prepared in this example was performed on an Empyrean model X-ray diffractometer manufactured by parnacho, the netherlands, with an operating voltage and an operating current of 40kV and 40mA, respectively, and a scanning range of 2 θ of 3 ° to 15 °, as shown in fig. 1.

The SEM image of the composite hydrogen storage material prepared in this example was obtained on a Nova Nano SEM 450 model field emission scanning electron microscope manufactured by FEI of the Netherlands, and the acceleration voltage tested was 15kV, and the result is shown in FIG. 2.

The room temperature hydrogen storage performance test of the composite hydrogen storage material prepared in this example was carried out on a BELSORP-HP type high pressure gas adsorption apparatus manufactured by Mickelbert corporation of Japan (MicrotracBEL), and the sample was vacuum-pretreated at 150 ℃ for 12 hours before the test, with the results shown in FIG. 3.

Example 3

The present embodiment provides a composite hydrogen storage material and a preparation method thereof, and the main differences from embodiment 1 are as follows: the adding amount of lithium chloride is different, and the steps are as follows:

(1) 3.352g of trimesic acid was dissolved in 45.6mL of a 1mol/L NaOH aqueous solution, and the solution was stirred at room temperature for 10min until complete dissolution, and the resulting solution was designated as a first solution.

(2) 0.226g of the graphene oxide suspension was added to 194.4g of ultrapure water, followed by ultrasonic treatment for 15 min. Then 4.52g of ferrous chloride tetrahydrate was added to the above solution and stirred at room temperature for 10min to be completely dissolved, and the resulting solution was designated as a second solution.

(3) And (3) placing the second solution on a magnetic stirrer for stirring, dropwise adding the first solution into the second solution, starting timing when the dropwise adding is finished, and stirring at room temperature for 24 hours. And after stirring, centrifuging the suspension at 6000rpm for 5min to realize solid-liquid separation, sequentially washing the centrifuged product with ultrapure water and absolute ethyl alcohol for three times, and drying the obtained product at 80 ℃ for 8h to obtain the MIL-100(Fe)/GO composite carrier.

(4) 1g of dry MIL-100(Fe)/GO composite carrier is taken and dispersed into 100ml of absolute ethyl alcohol. Then, 5mL of a 1mol/L lithium chloride ethanol solution was slowly added dropwise thereto, and stirred at room temperature for 8 hours. And finally, drying the centrifuged product at 80 ℃ for 8h to obtain the lithium ion doped metal organic framework/graphene oxide composite hydrogen storage material.

Powder X-ray diffraction of the composite hydrogen storage material prepared in this example was performed on an Empyrean model X-ray diffractometer manufactured by parnacho, the netherlands, with an operating voltage and an operating current of 40kV and 40mA, respectively, and a scanning range of 2 θ of 3 ° to 15 °, as shown in fig. 1.

The SEM image of the composite hydrogen storage material prepared in this example was obtained on a Nova Nano SEM 450 model field emission scanning electron microscope manufactured by FEI of the Netherlands, and the acceleration voltage tested was 15kV, and the result is shown in FIG. 2.

The room temperature hydrogen storage performance test of the composite hydrogen storage material prepared in this example was carried out on a BELSORP-HP type high pressure gas adsorption apparatus manufactured by Mickelbert corporation of Japan (MicrotracBEL), and the sample was vacuum-pretreated at 150 ℃ for 12 hours before the test, with the results shown in FIG. 3.

Comparative example 1

The comparative example provides a composite hydrogen storage material and a preparation method thereof, comprising the following steps:

(1) 3.352g of trimesic acid was weighed out and dissolved in 45.6mL of a 1mol/L NaOH aqueous solution, and the solution was sufficiently stirred and dissolved until it was completely dissolved, and the obtained solution was referred to as a first solution.

(2) 4.52g of ferrous chloride tetrahydrate is weighed and dissolved in 194.4g of water, the solution is fully stirred and dissolved until the solution is completely dissolved, and the obtained solution is marked as a second solution.

(3) And (3) stirring the second solution on a magnetic stirrer, dropwise adding the first solution into the second solution, starting timing after dropwise adding, and stirring for 24 hours at room temperature. And after stirring is finished, centrifuging the suspension at 6000rpm for 5min to realize solid-liquid separation, and washing with deionized water and absolute ethyl alcohol for three times respectively. Finally, the orange-yellow precipitate was dried in an oven at 80 ℃ for 8h to obtain MIL-100(Fe) synthesized at room temperature.

Powder X-ray diffraction of the composite hydrogen storage material prepared in this comparative example was performed on an Empyrean model X-ray diffractometer manufactured by parnacho, the netherlands, with an operating voltage and an operating current of 40kV and 40mA, respectively, and a scanning range of 2 θ of 3 ° to 15 °, the results are shown in fig. 1.

The SEM image of the composite hydrogen storage material prepared in this comparative example was obtained on a Nova Nano SEM 450 model field emission scanning electron microscope manufactured by FEI of the Netherlands, and the acceleration voltage tested was 15kV, and the result is shown in FIG. 2.

The room temperature hydrogen storage performance test of the composite hydrogen storage material prepared in this comparative example was carried out on a BELSORP-HP type high pressure gas adsorption apparatus manufactured by Mickelbert corporation of Japan (MicrotracBEL), and the sample was vacuum-pretreated at 150 ℃ for 12 hours before the test, with the results shown in FIG. 3.

Comparative example 2

This comparative example provides a composite hydrogen storage material and a method for preparing the same, the main differences from example 1 are: lithium chloride was not added, and the procedure was as follows:

(1) 3.352g of trimesic acid was dissolved in 45.6mL of a 1mol/L NaOH aqueous solution, and the solution was stirred at room temperature for 10min until complete dissolution, and the resulting solution was designated as a first solution.

(2) 0.226g of the graphene oxide suspension was added to 194.4g of ultrapure water, followed by ultrasonic treatment for 15 min. Then 4.52g of ferrous chloride tetrahydrate was added to the above solution and stirred at room temperature for 10min to be completely dissolved, and the resulting solution was designated as a second solution.

(3) And (3) placing the second solution on a magnetic stirrer for stirring, dropwise adding the first solution into the second solution, starting timing when the dropwise adding is finished, and stirring at room temperature for 24 hours. And after stirring, centrifuging the suspension at 6000rpm for 5min to realize solid-liquid separation, sequentially cleaning the centrifuged product with ultrapure water and absolute ethyl alcohol for three times, and drying the obtained product at 80 ℃ for 8h to obtain the MIL-100(Fe)/GO composite hydrogen storage material.

Powder X-ray diffraction of the composite hydrogen storage material prepared in this comparative example was performed on an Empyrean model X-ray diffractometer manufactured by parnacho, the netherlands, with an operating voltage and an operating current of 40kV and 40mA, respectively, and a scanning range of 2 θ of 3 ° to 15 °, the results are shown in fig. 4.

The SEM image of the composite hydrogen storage material prepared in this comparative example was obtained on a Nova Nano SEM 450 model field emission scanning electron microscope manufactured by FEI of the Netherlands, and the acceleration voltage tested was 15kV, and the result is shown in FIG. 5.

The room temperature hydrogen storage performance test of the composite hydrogen storage material prepared in this comparative example was carried out on a BELSORP-HP type high pressure gas adsorption apparatus manufactured by Mickelbert corporation of Japan (MicrotracBEL), and the sample was vacuum-pretreated at 150 ℃ for 12 hours before the test, with the results shown in FIG. 6.

As can be seen from the above examples and comparative examples, in FIG. 1, the composite hydrogen storage materials obtained in examples 1 to 3 maintained the crystal structure of MIL-100 (Fe). In FIG. 2, the composite hydrogen storage materials obtained in examples 1 to 3 exhibited octahedra structures and were substantially identical in microstructure to MIL-100 (Fe). In FIG. 3, the hydrogen adsorptions of examples 1, 2 and 3 under the conditions of 298K and 50bar reached 1.01 wt%, 2.02 wt% and 0.88 wt%, respectively, which were higher than 0.74 wt% of the conventional metal-organic framework MIL-100(Fe) of comparative example 1 under the same conditions. FIGS. 4-6 are XRD, SEM and hydrogen sorption capacity under 298K conditions for the MIL-100(Fe)/GO composite hydrogen storage material of comparative example 2. As can be seen from FIG. 6, the hydrogen adsorption capacity at 50bar was 0.96 wt%, which is lower than that of the lithium ion-doped composite hydrogen storage material of example 1.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.