High-performance solid-state hydrogen storage material and hydrogen energy electric bicycle using solid-state hydrogen storage as hydrogen source

Abstract

The application discloses a kind of high-performance solid-state hydrogen storage materials and hydrogen energy electric bicycle with solid-state hydrogen storage as hydrogen source, the hydrogen storage material is prepared by the following method: MgH2Powder, MgF2Powder, LiBH4Powder and catalyst are mixed according to the mass ratio MgH2:MgF2:LiBH4:Catalyst=45~65:6~13:18~30:5~20 Proportion is loaded into ball mill, ball material ratio 30~55:1, under argon protection, 300-650rpm Ball milling 4-10h, obtain high-performance solid-state hydrogen storage material.The application is compounded with MgH2Hydrogen storage alloy and LiBH4Hydrogen storage alloy, and is doped with MgF2And metal oxide-carbon-based material composite catalyst in it, can improve the hydrogen storage capacity of material, reduce hydrogen release reaction temperature.The hydrogen energy electric bicycle provided by the application has the advantages of safety, high efficiency, energy saving and environmental protection, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the hydrogen energy technology field, in particular to a high-performance solid-state hydrogen storage material and a hydrogen energy electric bicycle using solid-state hydrogen storage as hydrogen source. BACKGROUND

[0002] Electric vehicles are light, moderate speed, cheap, no noise and exhaust pollution, and take up less parking space, which can greatly improve the traffic efficiency of non-motorized lanes, and are very suitable for single short-distance travel in cities, and have incomparable advantages over other means of transportation. The current market electric bicycle power reserve is mainly borne by lead-acid batteries and lithium-ion batteries, both of which have the problems of short endurance, slow charging, difficult charging, and life attenuation, and lithium-ion batteries have certain safety hazards and the disadvantage of expensive replacement; and the pre-stage and post-stage pollution of lead-acid batteries and lithium batteries is also a long-term environmental problem.

[0003] Hydrogen energy is considered an ideal clean energy with the advantages of light weight, abundant reserves, and environmental friendliness. Solid-state hydrogen storage technology has the characteristics of high volume hydrogen storage density, low hydrogen storage pressure, and high safety, and has attracted widespread attention, and has great potential for application in electric bicycles. For example, patent CN114735128A provides a composite solid-state hydrogen storage fuel cell electric bicycle without battery assistance, and patent CN110606160B provides a hydrogen energy bicycle based on low-pressure solid-state hydrogen storage as hydrogen source.

[0004] Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6wt%), and magnesium resources are abundant, so it is a solid-state hydrogen storage material with great application prospect. However, the thermodynamic stability of MgH2 is too high, resulting in a too high hydrogen absorption and desorption temperature (above 300℃), which seriously restricts its practical application. LiBH4 has a high hydrogen storage density, and the theoretical hydrogen storage density is about 18.5wt%, which is much higher than that of magnesium hydride. However, the main defect of LiBH4 is that the hydrogen desorption temperature is too high (more than 400℃).

[0005] Therefore, it is necessary to improve the prior art to provide a more reliable solution. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a high-performance solid-state hydrogen storage material and a hydrogen energy electric bicycle using solid-state hydrogen storage as hydrogen source to solve the problems in the prior art.

[0007] To solve the above technical problems, the technical solution adopted by the present application is as follows: the present application provides a high-performance solid-state hydrogen storage material, which is prepared by the following method:

[0008] MgH2 powder, MgF2 powder, LiBH4 powder and catalyst are mixed in a ball mill in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 45-65:6-13:18-30:5-20, with a ball-to-material ratio of 30-55:1. The mixture is ball-milled at argon protection and 300-650 rpm for 4-10 hours to obtain a high-performance solid hydrogen storage material.

[0009] Preferably, the high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve and mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:8:25:12, and loaded into a ball mill with a ball-to-material ratio of 40:1, argon protection, and ball milling at 550 rpm for 6 hours to obtain a high-performance solid-state hydrogen storage material; wherein, intermittent ball milling is adopted, and the ball milling is stopped for 5 minutes after 25 minutes.

[0010] Preferably, the catalyst is a metal oxide-carbon-based material composite catalyst, which is prepared by the following method:

[0011] 1) Graphene oxide pretreatment;

[0012] 2) preparing porous cerium iron oxide microsphere-graphene oxide composite materials;

[0013] 3) Preparation of reduced carbon dots;

[0014] 4) The metal oxide-carbon-based material composite catalyst is prepared by a one-pot hydrothermal reaction using a porous cerium iron oxide microsphere-graphene oxide composite material and reduced carbon dots.

[0015] Preferably, the metal oxide-carbon-based material composite catalyst is prepared by the following method:

[0016] 1) Graphene oxide pretreatment:

[0017] adding graphene oxide to a mixed acid consisting of 95 wt % concentrated sulfuric acid and 30 wt % hydrogen peroxide, immersing the mixture under ultrasound, filtering, and drying to obtain pretreated graphene oxide;

[0018] 2) preparing porous cerium iron oxide microsphere-graphene oxide composite materials;

[0019] 2-1) adding 0.25-0.9 g of the treated graphene oxide to 25-100 mL of deionized water and ultrasonically dispersing the mixture for 15-60 min;

[0020] 2-2) 0.325-1.3 g of cerium nitrate hexahydrate, 0.6-2.4 g of ferric nitrate nonahydrate, 35-140 mL of deionized water, and 15-60 mL of ethanol were added to a container and stirred for 5-30 minutes. 0.85-3 g of polyvinyl pyrrolidone was then added and stirred for 2-10 minutes. The dispersion prepared in step 2-1) was then added with stirring. Stirring was continued for 10-45 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 160-200° C. for 8-20 hours.

[0021] 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried under vacuum, and then calcined in an air atmosphere at 420-550° C. for 1-4 hours to obtain a porous cerium iron oxide microsphere-graphene oxide composite material;

[0022] 3) Preparation of reduced carbon dots:

[0023] 3-1) Weigh 384-1152 mg of citric acid, 142-568 mg of lutein, 117-468 mg of bipyridine, 54-216 mg of o-phenylenediamine, and 119-476 mg of titanium tetrachloride into 125-500 mL of aqueous ethanol. After ultrasonic dispersion for 15-60 minutes, transfer the resulting mixture to a polytetrafluoroethylene-lined reactor and react at 180-210° C. for 3-12 hours.

[0024] The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 2:1 to 1:2;

[0025] 3-2) After the reaction is completed, the mixture is cooled to room temperature and filtered through a filter membrane. The filtrate is dialyzed in deionized water using a dialysis bag with a molecular weight cutoff of 800-1200 Da for 12-48 hours. The product in the dialysis bag is collected and freeze-dried to obtain reduced carbon dots;

[0026] 4) 0.5-2 g of the porous cerium iron oxide microsphere-graphene oxide composite material prepared in step 2) is added to a citric acid aqueous solution with a mass concentration of 1.5-6%, soaked for 2-15 minutes, and then filtered. The resulting solid product is added to 100-400 mL of deionized water, and 0.175-0.7 g of the reduced carbon dots prepared in step 3) is added under stirring. The mixture is ultrasonically dispersed for 30-90 minutes. The resulting mixture is transferred to a polytetrafluoroethylene-lined reactor, reacted at 120-160° C. for 2.5-8 hours, cooled to room temperature, centrifuged, and the solid product is washed with deionized water and vacuum-dried to obtain the metal oxide-carbon-based material composite catalyst.

[0027] Preferably, step 1) is specifically: adding 1 g of graphene oxide to 200 mL of a mixed acid consisting of 95 wt% concentrated sulfuric acid and 30 wt% hydrogen peroxide in a volume ratio of 3:1, ultrasonically treating at 60 ° C for 2 h, filtering, washing the solid product with deionized water until neutral, and vacuum drying at 80 ° C for 12 h to obtain pretreated graphene oxide.

[0028] Preferably, step 2) is specifically as follows: 2-1) adding 0.45 g of the treated graphene oxide to 50 mL of deionized water and ultrasonically dispersing the mixture for 30 min;

[0029] 2-2) 0.65 g of cerium nitrate hexahydrate, 1.2 g of ferric nitrate nonahydrate, 70 mL of deionized water, and 30 mL of ethanol were added to a container and stirred for 15 minutes. 1.5 g of polyvinyl pyrrolidone was then added and stirred for 5 minutes. The dispersion prepared in step 2-1) was then added with stirring. Stirring was continued for 20 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 180° C. for 14 hours.

[0030] 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried in vacuo at 60° C. for 12 h, and then calcined in air at 450° C. for 2 h to obtain a porous cerium iron oxide microsphere-graphene oxide composite material.

[0031] Preferably, step 3) is specifically:

[0032] 3-1) 768 mg of citric acid, 284 mg of lutein, 234 mg of bipyridine, 108 mg of o-phenylenediamine, and 238 mg of titanium tetrachloride were weighed and added to 250 mL of ethanol and aqueous solution. After ultrasonic dispersion for 45 minutes, the resulting mixture was transferred to a polytetrafluoroethylene-lined reactor and reacted at 190°C for 6 hours.

[0033] The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 1:1;

[0034] 3-2) After the reaction, the mixture was cooled to room temperature and filtered through a 0.22 μm filter membrane. The filtrate was dialyzed in deionized water using a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h. The product in the dialysis bag was collected and freeze-dried to obtain reduced carbon dots.

[0035] Preferably, step 4) is specifically as follows: 1 g of the porous cerium iron oxide microsphere-graphene oxide composite material prepared in step 2) is added to a 3% mass concentration of citric acid aqueous solution, soaked for 10 minutes and filtered, the resulting solid product is added to 200 mL of deionized water, 0.35 g of the reduced carbon dots prepared in step 3) is added under stirring, ultrasonically dispersed for 45 minutes, the resulting mixture is transferred to a polytetrafluoroethylene-lined reactor, reacted at 140° C. for 5 hours, cooled to room temperature, centrifuged, washed with deionized water, and vacuum dried at 70° C. to constant weight to obtain the metal oxide-carbon-based material composite catalyst.

[0036] The present invention also provides a hydrogen-powered electric bicycle using solid-state hydrogen storage as a hydrogen source, comprising a vehicle body, a hydrogen fuel cell system, and a drive system. The hydrogen fuel cell system utilizes the high-performance solid-state hydrogen storage alloy described above to provide hydrogen to generate electrical energy, and the drive system utilizes the electrical energy provided by the hydrogen fuel cell system to provide driving force for the vehicle body.

[0037] Preferably, the hydrogen fuel cell system includes a hydrogen storage bottle filled with the high-performance solid hydrogen storage alloy described above for providing hydrogen, and a fuel cell for generating electrical energy using hydrogen.

[0038] The beneficial effects of the present invention are:

[0039] The present invention provides a high-performance solid-state hydrogen storage material, which is obtained by compounding an MgH2 hydrogen storage alloy with a LiBH4 hydrogen storage alloy, and doping the alloy with MgF2 and a metal oxide-carbon-based material composite catalyst. The high hydrogen storage density of the LiBH4 hydrogen storage alloy can improve the hydrogen storage capacity of the material, while MgH2 can change the stability of the LiBH4 hydrogen desorption reaction product by interacting with LiBH4, reducing the reaction formation enthalpy, thereby reducing the hydrogen desorption reaction temperature. The doping of MgF2 can improve the hydrogen desorption kinetics of MgH2 by forming a solid solution with MgH2, and can further reduce the hydrogen desorption temperature of LiBH4 through the effects of F- on the lattice substitution of LiBH4. The added metal oxide-carbon-based material composite catalyst can simultaneously comprehensively improve the hydrogen absorption and desorption performance and cycle stability of the MgH2 and LiBH4 composite hydrogen storage material system.

[0040] The present invention further provides a hydrogen-powered electric bicycle based on the high-performance solid-state hydrogen storage material. The electric bicycle has the advantages of safety, high efficiency, energy saving and environmental protection, can meet the market demand for green travel, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The hydrogen release curves of the hydrogen storage materials prepared in Example 1 and Comparative Examples 1-7 under 0.1 MPa are shown;

[0042] Figure 2 The hydrogen absorption curves of the hydrogen storage materials prepared in Example 1, Comparative Example 2, and Comparative Example 6 at 6 MPa are shown;

[0043] Figure 3 The hydrogen release curves of the hydrogen storage materials prepared in Example 1, Comparative Example 2, and Comparative Example 6 at 350°C and 0.1 MPa are shown;

[0044] Figure 4 The test results of the initial hydrogen desorption temperature of the hydrogen storage materials prepared in Examples 1-4 and Comparative Examples 1-7 are as follows;

[0045] Figure 5 The test results of hydrogen storage density of hydrogen storage materials prepared in Examples 1-4 and Comparative Examples 1-7 are as follows;

[0046] Figure 6 The test results of the capacity retention rate of the hydrogen storage materials prepared in Examples 1-4 and Comparative Examples 1-7 are as follows;

[0047] Figure 7 is the infrared absorption spectrum of the reduced carbon dots Ti-CDs prepared in Example 1;

[0048] Figure 8 The XRD pattern of the metal oxide-carbon-based material composite catalyst prepared in Example 1;

[0049] Figure 9 These are the test results of the antioxidant properties of the reduced carbon dots Ti-CDs prepared in Example 1. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0051] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0052] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Materials and reagents used in the following examples are commercially available unless otherwise specified. In the following examples, where specific conditions are not specified, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Reagents and instruments used, where the manufacturer is not specified, are commercially available conventional products.

[0053] In a first aspect of the present invention, a high-performance solid-state hydrogen storage material is provided, which is prepared by the following method:

[0054] MgH2 powder, MgF2 powder, LiBH4 powder and catalyst are mixed in a ball mill in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 45-65:6-13:18-30:5-20, with a ball-to-material ratio of 30-55:1. The mixture is ball-milled at argon protection and 300-650 rpm for 4-10 hours to obtain a high-performance solid hydrogen storage material.

[0055] In a preferred embodiment, the ball milling process is performed in an intermittent ball milling mode, with ball milling for 20-30 minutes and stopping for 5-10 minutes.

[0056] In a preferred embodiment, the metal oxide-carbon-based material composite catalyst is prepared by the following method:

[0057] 1) Graphene oxide pretreatment:

[0058] adding graphene oxide to a mixed acid consisting of 95 wt % concentrated sulfuric acid and 30 wt % hydrogen peroxide, immersing the mixture under ultrasound, filtering, and drying to obtain pretreated graphene oxide;

[0059] 2) preparing porous cerium iron oxide microsphere-graphene oxide composite materials;

[0060] 2-1) adding 0.25-0.9 g of the treated graphene oxide to 25-100 mL of deionized water and ultrasonically dispersing the mixture for 15-60 min;

[0061] 2-2) 0.325-1.3 g of cerium nitrate hexahydrate, 0.6-2.4 g of ferric nitrate nonahydrate, 35-140 mL of deionized water, and 15-60 mL of ethanol were added to a container and stirred for 5-30 minutes. 0.85-3 g of polyvinyl pyrrolidone was then added and stirred for 2-10 minutes. The dispersion prepared in step 2-1) was then added with stirring. Stirring was continued for 10-45 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 160-200° C. for 8-20 hours.

[0062] 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried under vacuum, and then calcined in an air atmosphere at 420-550° C. for 1-4 hours to obtain a porous cerium iron oxide microsphere-graphene oxide composite material;

[0063] 3) Preparation of reduced carbon dots:

[0064] 3-1) Citric acid 384-1152 mg, lutein 142-568 mg, bipyridine 117-468 mg, o-phenylenediamine 54-216 mg, titanium tetrachloride 119-476 mg are weighed into 125-500 mL of an ethanol aqueous solution, and the resulting mixture is ultrasonically dispersed for 15-60 min, and then transferred into a polytetrafluoroethylene-lined reaction kettle, and reacted at 180-210 DEG C for 3-12 h;

[0065] The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 2:1 to 1:2.

[0066] 3-2) After the reaction is completed, the mixture is cooled to room temperature, filtered with a filter membrane, and the filtrate is dialyzed in deionized water for 12-48 h using a dialysis bag with a molecular weight cut-off of 800-1200 Da, and the product in the dialysis bag is collected, and freeze-dried to obtain reduced carbon dots.

[0067] 4) 0.5-2 g of the porous cerium-iron oxide microsphere-graphene oxide composite material prepared in step 2) is added to a 1.5-6% citric acid aqueous solution, soaked for 2-15 min, and then filtered, and the obtained solid product is added to 100-400 mL of deionized water, and 0.175-0.7 g of the reduced carbon dots prepared in step 3) is added under stirring, and ultrasonically dispersed for 30-90 min, and the resulting mixture is transferred into a polytetrafluoroethylene-lined reaction kettle, and reacted at 120-160 DEG C for 2.5-8 h, and then cooled to room temperature, and centrifuged and filtered, and the solid product is washed with deionized water, and vacuum dried to obtain a metal oxide-carbon-based material composite catalyst.

[0068] In a second aspect, the application provides a hydrogen energy electric bicycle using solid-state hydrogen storage alloy as hydrogen source, which comprises a vehicle body, a hydrogen fuel cell system and a driving system.

[0069] In a preferred embodiment, the hydrogen fuel cell system comprises a hydrogen storage bottle for providing hydrogen, which is internally filled with the high-performance solid-state hydrogen storage alloy, and a fuel cell for generating electric energy by using the hydrogen.

[0070] In the present invention, a MgH2 hydrogen storage alloy is compounded with a LiBH4 hydrogen storage alloy, and MgF2 and a metal oxide-carbon-based material composite catalyst are doped therein. The high hydrogen storage density of the LiBH4 hydrogen storage alloy can improve the hydrogen storage capacity of the material, while MgH2 can change the stability of the LiBH4 hydrogen desorption reaction product by interacting with LiBH4, reduce the reaction formation enthalpy, and thus reduce the hydrogen desorption reaction temperature. The doping of MgF2 can improve the hydrogen desorption kinetics of MgH2 by forming a solid solution with MgH2, and can further reduce the hydrogen desorption temperature of LiBH4 through effects such as F- lattice substitution on LiBH4. The added metal oxide-carbon-based material composite catalyst can simultaneously comprehensively improve the hydrogen absorption and desorption performance and cyclic stability of the MgH2 and LiBH4 composite hydrogen storage material system. Ultimately, the prepared high-performance solid-state hydrogen storage alloy has high hydrogen storage capacity, excellent cyclic stability and good hydrogen absorption and desorption performance, and has great potential for application in the fields of hydrogen electric vehicles and hydrogen cars. The principles of the present invention are described in more detail below to facilitate understanding of the present invention.

[0071] MgH2 hydrogen storage alloy has a high hydrogen storage capacity (theoretical hydrogen storage density of 7.6wt%), abundant resources and low price. It is a very promising hydrogen storage material, but it also has some defects, including: high hydrogen desorption temperature, slow hydrogen absorption and desorption reaction rate, and poor cyclic stability.

[0072] The hydrogen release reaction of MgH2 is:

[0073] MgH2→Mg+H2

[0074] LiBH4 has a high hydrogen storage density, with a theoretical hydrogen storage density of about 18.5wt%. Its main defect is that the dehydrogenation temperature is too high (over 400°C). Its dehydrogenation reaction is:

[0075] LiBH4→LiH+B+H2

[0076] (1) Adding MgH2 has been shown to change the decomposition pathway of LiBH4, thereby changing the stability of the reaction products, reducing the reaction enthalpy, and ultimately effectively reducing the dehydrogenation temperature of LiBH4. The main reactions involved are as follows (John, J, Vajo, et al. Reversible Storage of Hydrogen in Destabilized LiBH4[J]. The Journal of Physical Chemistry B, 2005, 109(9): 3719–3722. DOI: 10.1021 / jp040769o.):

[0077] 2LiBH4+MgH2→2LiH+MgB2+H2

[0078] (2) After MgF2 is doped into the material system, on the one hand, it can be dissolved in MgH2. During the dehydrogenation heating process, MgF2 precipitates from MgH2, causing the lattice parameters to change, resulting in the instability and breakage of the Mg-H bond, thereby promoting the hydrogen release reaction of MgH2 (Zhang Jian. Hydrogen storage performance of new catalyst ball-milled doped magnesium hydride [D]. South China University of Technology, 2013.); on the other hand, the F- introduced by MgF2 can enter the LiBH4 lattice to form LiBH 1-x F x The substitution structure of LiBH is different from that of F- and H- due to the difference in ionic radius. 1-x F x It can provide more reactive centers and hydrogen atom diffusion channels than LiBH4, thereby further reducing the dehydrogenation temperature of LiBH4 (Wang Xinhua, Xu Lou, Wu Xiaocheng, et al. Effect of Ce-based catalysts on the dehydrogenation performance of 2LiBH4 / MgH2 [J]. Rare Metal Materials and Engineering, 2011(011):040.). It can be seen that the doping of MgF2 can effectively improve the dehydrogenation kinetics of both MgF2 and LiBH4.

[0079] (3) The catalyst in the present invention is a metal oxide-carbon-based material composite catalyst, which is obtained by in situ grafting of a graphene oxide composite material with porous cerium iron oxide microspheres and then modifying it with reducing carbon dots. It can significantly improve the hydrogen absorption and desorption performance and cycle stability of MgF2 and LiBH4.

[0080] 1. The preparation mechanism is:

[0081] First, graphene oxide was pretreated with mixed acid to increase the number of functional groups on its surface, such as carboxyl groups, to facilitate subsequent modification. Then, using polyvinyl pyrrolidone as a surfactant, a hydrothermal reaction combined with high-temperature calcination was used to in situ graft the pretreated graphene oxide with porous structures of ceria and ferric oxide composite microspheres, thus obtaining the porous cerium iron oxide microsphere-graphene oxide composite material CeFeO@GO.

[0082] Then, a titanium-doped reduced carbon dot Ti-CDs with good reduction performance was prepared by hydrothermal reaction using citric acid 3, lutein, bipyridine as carbon sources, o-phenylenediamine as nitrogen source, and titanium tetrachloride as doping component.

[0083] Finally, the reduced carbon dots are modified onto the porous cerium iron oxide microsphere-graphene oxide composite material through a one-pot hydrothermal reaction, resulting in the final metal oxide-carbon-based composite catalyst Ti-CDs@CeFeO@GO. In this step, the porous cerium iron oxide microsphere-graphene oxide composite material is soaked in dilute acid (citric acid), which produces a large number of metal ions (Ce4+, Fe3+) on its surface. These ions bind to functional groups such as carboxyl and hydroxyl groups on the surface of the reduced carbon dots, causing a large number of reduced carbon dots to attach to the porous cerium iron oxide microsphere-graphene oxide composite material. A hydrothermal reaction then forms stable chemical bonds, achieving a strong grafting, ultimately constructing the "reduced carbon dots + porous cerium iron oxide microspheres + graphene oxide" ternary composite structure: Ti-CDs@CeFeO@GO.

[0084] 2. Mechanism of Action

[0085] A. The role of porous cerium iron oxide

[0086] Cerium dioxide has excellent catalytic properties for hydrogen absorption and desorption in hydrogen storage materials. This catalytic performance mainly depends on the valence change characteristics of cerium ions and the oxygen vacancy concentration that changes with the valence change of cerium ions (Zhang Guofang, Zhai Tingting, Hou Zhonghui, et al. Study on the influence of spectral characteristics of nano-CeO2-xNx solid solution on its catalytic performance [J]. Spectroscopy and Spectral Analysis, 2018, 38(10): 7. DOI: 10.3964 / j.issn.1000-0593(2018)10-3192-07.).

[0087] The porous cerium iron oxide (ferric oxide doped with cerium dioxide) microspheres have a rich mesoporous structure, which can enhance the material's ability to physically adsorb and store hydrogen. Their high specific surface area allows the material surface to expose more active sites, providing more channels for hydrogen diffusion, thereby improving hydrogen absorption and desorption performance. They can also act as a grinding aid during ball milling.

[0088] As a transition metal oxide, ferric oxide can reduce the hydrogen absorption and desorption temperature of hydrogen storage materials such as MgF2 and improve the hydrogen absorption and desorption kinetics (Zhang Yao, Li Shouquan, Ying Tiao, et al. Effect of ball milling surface coating on the electrochemical properties of magnesium-based hydrogen storage alloys [J]. Journal of Nonferrous Metals, 2001, 11(004): 582-586. DOI: 10.3321 / j.issn: 1004-0609.2001.04.010.).

[0089] On the other hand, the doping of nickel and iron metals and the doping of titanium in carbon dots can improve the dispersion performance of graphene oxide in the hydrogen storage alloy material system and promote its uniform mixing with the hydrogen storage alloy material system.

[0090] B. The role of graphene oxide

[0091] By attaching to the surface of hydrogen storage alloys, graphene oxide can enhance their specific surface area and lubrication effect. During ball milling, the graphene oxide surface breaks into irregular flakes, creating more edge sites and hydrogen channels, thereby improving the material's hydrogen storage performance (Yankun Wang, Xusheng Liu, Yuping Chen, et al. High energy ball milling composite modifcation of Mg2Ni hydrogen storage alloy bygraphene and MWCNTs[J]. International journal of hydrogen energy, 50(2024)1562–1573.). In addition, graphene oxide has high thermal conductivity and can improve the thermal conductivity and uniformity of the material by forming a thermal conductive network within the system. The excellent mechanical properties of graphene oxide can reduce the pulverization of hydrogen storage alloys during use and improve their cyclic stability.

[0092] C. Effect of Titanium-Cerium Doped Carbon Dots

[0093] The lutein and bipyridine in the raw materials for preparing the carbon dots of the present invention both have good reducing properties, and the carbon dots also inherit this property well, can provide antioxidant properties in the hydrogen storage material system, can effectively avoid the oxidation of MgF2 and LiBH4, and thus can significantly improve the cyclic stability of the hydrogen storage material.

[0094] Carbon doped titanium has a catalytic effect on the hydrogen release process of hydrogen storage alloys, which can improve the activation performance and increase the service life of the material (Hu Sumei. Research on hydrogen storage properties of magnesium-based carbon nanotube composites [D]. Lanzhou University of Technology, 2009. DOI: 10.7666 / d.y1464595.).

[0095] In addition, during the ball milling process, the ball milling action will destroy the oxide layer on the surface of the alloy. As a nano-carbon material, carbon dots have good reducing properties, which enable them to react with the oxide layer and / or prevent the formation of a new oxide layer, thereby improving the activation performance of the alloy (Wu Junqing, Zhou Shixue, Yang Minjian, et al. Hydrogen storage function of carbon materials [J]. Coal Science and Technology, 2006, 34(11): 4. DOI: 10.3969 / j.issn.0253-2336.2006.11.025.).

[0096] Furthermore, the small size, high specific surface area and rich surface functional groups of carbon dots that can interact with hydrogen molecules can provide a large number of active sites for hydrogen adsorption, thereby improving the physical hydrogen storage capacity; at the same time, carbon dots have excellent electron transfer properties and can increase the electron density, which can be beneficial to catalyze the promotion of hydrogen absorption and desorption reactions.

[0097] The present invention further provides promising application scenarios for this high-performance solid-state hydrogen storage material, such as hydrogen-powered electric bicycles. Of course, this high-performance solid-state hydrogen storage material also has the potential for application in many other scenarios, including hydrogen fuel cell vehicles, distributed energy supply, large-scale batteries, and backup power supplies. It should be understood that when this high-performance solid-state hydrogen storage material is applied to scenarios such as hydrogen-powered electric bicycles and hydrogen fuel cell vehicles, a corresponding thermal management system is required to provide the temperature environment required for hydrogen desorption. However, since the hydrogen desorption temperature of the material in the present invention is significantly reduced, the requirements for the thermal management system are lower, making its application more conducive.

[0098] The above is the overall concept of the present invention. Detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0099] Example 1

[0100] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve, mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:8:25:12, and loaded into a ball mill with a ball-to-material ratio of 40:1. The material is ball-milled at 550 rpm for 6 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0101] In this embodiment, the catalyst is a metal oxide-carbon-based material composite catalyst, which is prepared by the following method:

[0102] 1) Graphene oxide pretreatment:

[0103] 1 g of graphene oxide (flaky graphene oxide, thickness range 0.5-1 nm, flake diameter range 2-5 μm, purchased from Suzhou Kaifa New Material Technology Co., Ltd., the same as in the following examples and comparative examples) was added to 200 mL of a mixed acid consisting of 95 wt% concentrated sulfuric acid and 30 wt% hydrogen peroxide in a volume ratio of 3:1, and ultrasonically treated at 60 ° C for 2 h. The solid product was filtered, washed with deionized water until neutral, and vacuum dried at 80 ° C for 12 h to obtain pretreated graphene oxide.

[0104] 2) Preparation of porous cerium iron oxide microspheres-graphene oxide composite materials:

[0105] 2-1) 0.45 g of the treated graphene oxide was added to 50 mL of deionized water and ultrasonically dispersed for 30 min;

[0106] 2-2) 0.65 g of cerium nitrate hexahydrate, 1.2 g of ferric nitrate nonahydrate, 70 mL of deionized water, and 30 mL of ethanol were added to a container and stirred for 15 minutes. 1.5 g of polyvinyl pyrrolidone was then added and stirred for 5 minutes. The dispersion prepared in step 2-1) was then added with stirring. Stirring was continued for 20 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 180° C. for 14 hours.

[0107] 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried in vacuo at 60° C. for 12 h, and then calcined in air at 450° C. for 2 h to obtain a porous cerium iron oxide microsphere-graphene oxide composite material.

[0108] 3) Preparation of reduced carbon dots:

[0109] 3-1) 768 mg of citric acid, 284 mg of lutein, 234 mg of bipyridine, 108 mg of o-phenylenediamine, and 238 mg of titanium tetrachloride were weighed and added to 250 mL of ethanol and aqueous solution. After ultrasonic dispersion for 45 minutes, the resulting mixture was transferred to a polytetrafluoroethylene-lined reactor and reacted at 190°C for 6 hours.

[0110] The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 1:1;

[0111] 3-2) After the reaction, the mixture was cooled to room temperature and filtered through a 0.22 μm filter membrane. The filtrate was dialyzed in deionized water using a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h. The product in the dialysis bag was collected and freeze-dried to obtain reduced carbon dots.

[0112] 4) A metal oxide-carbon-based composite catalyst was prepared by a one-pot hydrothermal reaction using porous cerium iron oxide microspheres-graphene oxide composite materials and reduced carbon dots:

[0113] 1 g of the porous cerium iron oxide microsphere-graphene oxide composite material prepared in step 2) was added to a 3% mass concentration of citric acid aqueous solution, soaked for 10 minutes, and then filtered. The resulting solid product was added to 200 mL of deionized water, and 0.35 g of the reduced carbon dots prepared in step 3) was added under stirring. Ultrasonic dispersion was performed for 45 minutes. The resulting mixture was transferred to a polytetrafluoroethylene-lined reactor, reacted at 140° C. for 5 hours, cooled to room temperature, and centrifuged. The solid product was washed with deionized water and vacuum dried at 70° C. to constant weight to obtain a metal oxide-carbon-based material composite catalyst.

[0114] Example 2

[0115] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve, mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:9:25:11, and loaded into a ball mill with a ball-to-material ratio of 40:1. The material is ball-milled at 550 rpm for 6 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0116] Example 3

[0117] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve, mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:10:25:10, and loaded into a ball mill with a ball-to-material ratio of 40:1. The material is ball-milled at 550 rpm for 6 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0118] Example 4

[0119] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve and mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:8:25:12, and then loaded into a ball mill with a ball-to-material ratio of 35:1. The material is ball-milled at 500 rpm for 8 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0120] Example 5

[0121] A hydrogen-powered electric bicycle using solid-state hydrogen storage as a hydrogen source comprises a vehicle body, a hydrogen fuel cell system, and a drive system. The hydrogen fuel cell system utilizes the high-performance solid-state hydrogen storage alloy of Example 1 to provide hydrogen to generate electrical energy, and the drive system utilizes the electrical energy provided by the hydrogen fuel cell system to provide driving force for the vehicle body.

[0122] The hydrogen fuel cell system includes a hydrogen storage bottle filled with the high-performance solid hydrogen storage alloy of Example 1 for providing hydrogen and a fuel cell for generating electricity using hydrogen.

[0123] Comparative Example 1

[0124] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder and LiBH4 powder are passed through a 200-mesh sieve and mixed with a catalyst in a mass ratio of MgH2:LiBH4:catalyst = 55:25:12, and the mixture is loaded into a ball mill with a ball-to-material ratio of 40:1. The mixture is ball-milled at 550 rpm for 6 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0125] The catalyst in this example is the same as that in Example 1.

[0126] Comparative Example 2

[0127] A high-performance solid-state hydrogen storage material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve, mixed in a mass ratio of MgH2:MgF2:LiBH4=55:8:25, and loaded into a ball mill with a ball-to-material ratio of 40:1. The material is ball-milled at 550 rpm for 6 hours under argon protection to obtain the high-performance solid-state hydrogen storage material; wherein the process is operated in an intermittent ball milling mode, with ball milling for 25 minutes and resting for 5 minutes.

[0128] Comparative Example 3

[0129] This example is basically the same as Example 1, except that:

[0130] The catalyst in this example is the porous cerium iron oxide microsphere-graphene oxide composite material in Example 1.

[0131] Comparative Example 4

[0132] This example is basically the same as Example 1, except that:

[0133] The catalyst was prepared by the following method:

[0134] 1) Graphene oxide pretreatment, the same as in Example 1;

[0135] 2) preparing a porous cerium iron oxide microsphere-graphene oxide composite material, the same as in Example 1;

[0136] 3) Preparation of reduced carbon dots:

[0137] 3-1) 768 mg of citric acid, 284 mg of lutein, 234 mg of bipyridine, and 108 mg of o-phenylenediamine were weighed and added to 250 mL of ethanol and aqueous solution. After ultrasonic dispersion for 45 minutes, the resulting mixture was transferred to a polytetrafluoroethylene-lined reactor and reacted at 190°C for 6 hours.

[0138] The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 1:1;

[0139] 3-2) After the reaction is completed, cool to room temperature, filter with a filter membrane of 0.22 μm, dialyze the filtrate in a dialysis bag with a molecular weight cut-off of 1000 Da in deionized water for 24 h, collect the product in the dialysis bag, and freeze-dry to obtain the reduced carbon dots.

[0140] 4) Take 1 g of the porous cerium-iron oxide microsphere-graphene oxide composite material prepared in step 2) and add it to a 3% mass concentration citric acid aqueous solution, soak for 10 min, then filter, add the obtained solid product to 200 mL of deionized water, and add 0.35 g of the reduced carbon dots prepared in step 3) under stirring, ultrasonic dispersion for 45 min, transfer the obtained mixture to a polytetrafluoroethylene-lined reaction kettle, react at 140°C for 5 h, cool to room temperature, centrifugal filter, wash the solid product with deionized water, and vacuum dry at 70°C to constant weight to obtain the catalyst.

[0141] Comparative Example 5

[0142] This example is basically the same as Example 1, except that:

[0143] The catalyst is prepared by the following method:

[0144] 1) Graphene oxide pretreatment, same as Example 1;

[0145] 2) Preparation of porous oxide microsphere-graphene oxide composite material:

[0146] 2-1) Take 0.45 g of the treated graphene oxide and add it to 50 mL of deionized water, ultrasonic dispersion for 30 min;

[0147] 2-2) Take 1.2 g of iron nitrate nonahydrate, 70 mL of deionized water, and 30 mL of ethanol, add them to a container, stir for 15 min, then add 1.5 g of polyvinylpyrrolidone, stir for 5 min, then add the dispersion prepared in step 2-1) under stirring, continue stirring for 20 min, then transfer the obtained mixture to a polytetrafluoroethylene-lined reaction kettle, react at 180°C for 14 h;

[0148] 2-3) After the reaction is completed, cool to room temperature, filter, wash with ethanol and deionized water in turn, vacuum dry at 60°C for 12 h, then calcine in air at 450°C for 2 h to obtain the porous oxide microsphere-graphene oxide composite material.

[0149] 3) Preparation of reduced carbon dots, same as Example 1;

[0150] 4) 1 g of the porous oxide microsphere-graphene oxide composite material prepared in step 2) was added to a 3% mass concentration of citric acid aqueous solution, soaked for 10 min, and filtered. The resulting solid product was added to 200 mL of deionized water, and 0.35 g of the reduced carbon dots prepared in step 3) was added under stirring. The mixture was ultrasonically dispersed for 45 min. The resulting mixture was transferred to a polytetrafluoroethylene-lined reactor, reacted at 140° C. for 5 h, cooled to room temperature, and centrifuged. The solid product was washed with deionized water and vacuum-dried at 70° C. to constant weight to obtain a catalyst.

[0151] Comparative Example 6

[0152] This example is basically the same as Example 1, except that:

[0153] The catalyst in this example is a mixture of pretreated graphene oxide and reduced carbon dots in a mass ratio of 10:3.5.

[0154] The pre-treated graphene oxide is the same as that in Example 1, and the reduced carbon dots are also the same as those in Example 1.

[0155] Comparative Example 7

[0156] This example is basically the same as Example 1, except that:

[0157] The catalyst in this example is a mixture of porous cerium iron oxide microspheres-graphene oxide composite material and reduced carbon dots in a mass ratio of 10:3.5.

[0158] The porous cerium iron oxide microsphere-graphene oxide composite material is the same as that in Example 1, and the reduced carbon dots are also the same as those in Example 1.

[0159] Performance testing and characterization

[0160] 1. Hydrogen storage density and hydrogen absorption and desorption performance tests were performed using the H-Sorb 2600 fully automatic PCT hydrogen storage material tester.

[0161] 2. Cyclic stability test: 40 complete hydrogen absorption / desorption cycles were performed at 350°C (hydrogen desorption pressure 0.1 MPa, hydrogen absorption pressure 6 MPa), the hydrogen storage capacity (hydrogen storage density) was measured, and then the capacity retention rate was calculated. Capacity retention rate = (hydrogen storage capacity after multiple cycles / initial hydrogen storage capacity) × 100%.

[0162] The test results are shown in Table 1 and Figure 1-6 As shown:

[0163] Table 1

[0164]

[0165]

[0166] Figure 1 The hydrogen release curves of the hydrogen storage materials prepared in Example 1 and Comparative Examples 1-7 under 0.1 MPa are shown in FIG. Figure 2 The hydrogen absorption curves of the hydrogen storage materials prepared in Example 1, Comparative Example 2, and Comparative Example 6 at 6 MPa are shown below: Figure 3 The hydrogen release curves of the hydrogen storage materials prepared in Example 1, Comparative Example 2, and Comparative Example 6 at 350°C and 0.1 MPa are shown. Figure 4-Figure 6 The test results of the initial hydrogen desorption temperature, hydrogen storage density, and capacity retention rate of the hydrogen storage materials prepared in Examples 1-4 and Comparative Examples 1-7 are shown in sequence.

[0167] According to Table 1, Figure 1 as well as Figure 4-Figure 6 It can be seen from the test results that the hydrogen storage materials prepared in Examples 1-4 have lower hydrogen desorption temperature, higher hydrogen storage density and excellent cycle stability, and have excellent comprehensive performance. In Comparative Example 1, MgF2 is not doped, resulting in a significant increase in its initial hydrogen desorption temperature; in Comparative Example 2, due to the lack of doped catalyst, the initial hydrogen desorption temperature increases significantly, and the cycle stability performance (capacity retention rate) decreases significantly; the reason for the increase in initial hydrogen desorption temperature and the decrease in cycle stability performance in Comparative Example 3 is that the reduced carbon dots are not grafted into the catalyst; the changes in initial hydrogen desorption temperature and capacity retention rate in Comparative Example 4 can illustrate the effect of titanium doping of the reduced carbon dots; the results of Comparative Example 5 can illustrate the promoting effect of cerium doping of porous cerium-iron composite oxide microspheres on hydrogen desorption performance; in Comparative Example 6, all performance factors decreased, which was attributed to the lack of porous cerium-iron composite oxide microspheres doped in the catalyst; the decrease in various performance factors in Comparative Example 7 shows that the effect of constructing the "reduced carbon dots + porous cerium-iron oxide microspheres + graphene oxide" ternary composite structural system Ti-CDs@CeFeO@GO is better than the scheme of directly blending and adding reduced carbon dots and porous cerium-iron oxide microspheres-graphene oxide composite materials.

[0168] according to Figure 2 and Figure 3 The results show that the hydrogen absorption and desorption kinetics of Example 1 are significantly better than those of Comparative Examples 2 and 6.

[0169] In order to further illustrate the mechanism of the metal oxide-carbon-based material composite catalyst in the present invention, the following performance characterization test is carried out using Example 1 as an example.

[0170] (1)Reference Figure 7 , is the infrared absorption spectrum of the reduced carbon dots Ti-CDs prepared in Example 1. It can be seen that the surface of the carbon dots has abundant functional groups such as carboxyl, hydroxyl, and amino groups. The appearance of the characteristic peak of the Ti-O bond indicates the successful doping of Ti.

[0171] (2)Reference Figure 8 , which is the XRD pattern of the metal oxide-carbon-based material composite catalyst prepared in Example 1, and the pattern can illustrate the successful synthesis of the catalyst.

[0172] (3) The antioxidant performance of the reduced carbon dots (Ti-CDs) prepared in Example 1 was tested using the following method:

[0173] The reduced carbon dots prepared in Example 1 were prepared into a dispersion with a concentration of 0.5 mg / mL using ethanol, and the antioxidant properties of the dispersion were tested at different times using a DPPH free radical scavenging ability test kit (provided by Hefei Lyle Biotechnology Co., Ltd.).

[0174] Determination principle: DPPH free radical has a single electron, its alcohol solution is purple, and has strong absorption at 515nm. When there is an antioxidant, the DPPH free radical is scavenged, the color becomes lighter, and the absorbance at 515nm decreases. Within a certain range, the change in absorbance is proportional to the degree of free radical scavenging, that is, the lower the absorbance at 515nm, the stronger the nitrogen free radical scavenging ability and the stronger the antioxidant performance.

[0175] Reference Figure 9 , which is the test result. It can be seen that the reduced carbon dots have good reduction performance.

[0176] (4) The BET specific surface area of ​​the metal oxide-carbon-based material composite catalyst prepared in Example 1 was measured using a BET specific surface area analyzer and was 283 m 2 / g.

[0177] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A high-performance solid-state hydrogen storage material, characterized in that: It is prepared by the following method: MgH2 powder, MgF2 powder, LiBH4 powder and catalyst are mixed in a ball mill at a mass ratio of MgH2:MgF2:LiBH4:catalyst = 45-65:6-13:18-30:5-20, with a ball-to-material ratio of 30-55:1, and ball milled at 300-650 rpm for 4-10 hours under argon protection to obtain a high-performance solid hydrogen storage material; The catalyst is a metal oxide-carbon-based material composite catalyst, which is prepared by the following method: 1) Graphene oxide pretreatment; 2) Preparation of porous cerium iron oxide microsphere-graphene oxide composites; 3) Preparation of reduced carbon dots; 4) The metal oxide-carbon-based material composite catalyst is prepared by a one-pot hydrothermal reaction using a porous cerium iron oxide microsphere-graphene oxide composite material and reduced carbon dots.

2. The high performance solid-state hydrogen storage material according to claim 1, characterized in that: The material is prepared by the following method: MgH2 powder, MgF2 powder, and LiBH4 powder are passed through a 200-mesh sieve and mixed with a catalyst in a mass ratio of MgH2:MgF2:LiBH4:catalyst = 55:8:25:12, and then loaded into a ball mill with a ball-to-material ratio of 40:

1. The material is ball-milled at 550 rpm for 6 hours under argon protection to obtain a high-performance solid-state hydrogen storage material; the material is ball-milled in an intermittent ball milling mode, with ball milling for 25 minutes and stopping for 5 minutes.

3. The high performance solid-state hydrogen storage material according to claim 1, characterized in that: The metal oxide-carbon-based material composite catalyst is prepared by the following method: 1) Graphene oxide pretreatment: adding graphene oxide to a mixed acid consisting of 95 wt % concentrated sulfuric acid and 30 wt % hydrogen peroxide, immersing the mixture under ultrasound, filtering, and drying to obtain pretreated graphene oxide; 2) Preparation of porous cerium iron oxide microsphere-graphene oxide composites; 2-1) Add 0.25-0.9 g of treated graphene oxide to 25-100 mL of deionized water and ultrasonically disperse for 15-60 minutes; 2-2) 0.325-1.3 g of cerium nitrate hexahydrate, 0.6-2.4 g of ferric nitrate nonahydrate, 35-140 mL of deionized water, and 15-60 mL of ethanol were added to a container and stirred for 5-30 minutes. 0.85-3 g of polyvinyl pyrrolidone was then added and stirred for 2-10 minutes. The dispersion prepared in step 2-1) was then added while stirring. Stirring was continued for 10-45 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 160-200° C. for 8-20 hours. 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried under vacuum, and then calcined in air at 420-550°C for 1-4 hours to obtain a porous cerium iron oxide microsphere-graphene oxide composite material; 3) Preparation of reduced carbon dots: 3-1) Weigh 384-1152 mg of citric acid, 142-568 mg of lutein, 117-468 mg of bipyridine, 54-216 mg of o-phenylenediamine, and 119-476 mg of titanium tetrachloride into 125-500 mL of ethanol and disperse them ultrasonically for 15-60 minutes. Then, transfer the resulting mixture to a polytetrafluoroethylene-lined reactor and react at 180-210°C for 3-12 hours. The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 2:1 to 1:2; 3-2) After the reaction is completed, the mixture is cooled to room temperature and filtered through a membrane. The filtrate is dialyzed in deionized water using a dialysis bag with a molecular weight cutoff of 800-1200 Da for 12-48 hours. The product in the dialysis bag is collected and freeze-dried to obtain reduced carbon dots. 4) 0.5-2 g of the porous cerium iron oxide microsphere-graphene oxide composite material prepared in step 2) is added to a 1.5-6% mass concentration of citric acid aqueous solution, soaked for 2-15 minutes, and then filtered. The resulting solid product is added to 100-400 mL of deionized water, and 0.175-0.7 g of the reduced carbon dots prepared in step 3) is added under stirring. The mixture is ultrasonically dispersed for 30-90 minutes. The resulting mixture is transferred to a polytetrafluoroethylene-lined reactor, reacted at 120-160° C. for 2.5-8 hours, cooled to room temperature, centrifuged, and the solid product is washed with deionized water and vacuum dried to obtain the metal oxide-carbon-based material composite catalyst.

4. The high performance solid-state hydrogen storage material according to claim 3, characterized in that: Step 1) is specifically as follows: 1 g of graphene oxide is added to 200 mL of a mixed acid consisting of 95 wt% concentrated sulfuric acid and 30 wt% hydrogen peroxide in a volume ratio of 3:1, ultrasonically treated at 60°C for 2 hours, filtered, and the solid product is washed with deionized water until neutral, and vacuum dried at 80°C for 12 hours to obtain pretreated graphene oxide.

5. The high performance solid-state hydrogen storage material according to claim 3, characterized in that: Step 2) is specifically as follows: 2-1) 0.45 g of the treated graphene oxide was added to 50 mL of deionized water and ultrasonically dispersed for 30 minutes; 2-2) 0.65 g of cerium nitrate hexahydrate, 1.2 g of ferric nitrate nonahydrate, 70 mL of deionized water, and 30 mL of ethanol were added to a container and stirred for 15 minutes. 1.5 g of polyvinyl pyrrolidone was then added and stirred for 5 minutes. The dispersion prepared in step 2-1) was then added with stirring. Stirring was continued for 20 minutes. The resulting mixture was then transferred to a polytetrafluoroethylene-lined reactor and reacted at 180°C for 14 hours. 2-3) After the reaction is completed, the mixture is cooled to room temperature, filtered, washed with ethanol and deionized water in sequence, dried in a vacuum at 60°C for 12 hours, and then calcined at 450°C in an air atmosphere for 2 hours to obtain a porous cerium iron oxide microsphere-graphene oxide composite material.

6. The high performance solid-state hydrogen storage material according to claim 3, characterized in that: Step 3) is as follows: 3-1) Weigh 768 mg of citric acid, 284 mg of lutein, 234 mg of bipyridine, 108 mg of o-phenylenediamine, and 238 mg of titanium tetrachloride into 250 mL of ethanol and ultrasonically disperse for 45 minutes. Then, transfer the resulting mixture to a polytetrafluoroethylene-lined reactor and react at 190°C for 6 hours. The ethanol aqueous solution is obtained by mixing ethanol and deionized water in a volume ratio of 1:1; 3-2) After the reaction, the mixture was cooled to room temperature and filtered through a 0.22 μm filter membrane. The filtrate was dialyzed in deionized water using a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h. The product in the dialysis bag was collected and freeze-dried to obtain reduced carbon dots.

7. The high performance solid-state hydrogen storage material according to claim 3, characterized in that: Step 4) is specifically as follows: 1 g of the porous cerium iron oxide microsphere-graphene oxide composite material prepared in step 2) is added to a 3% mass concentration of citric acid aqueous solution, soaked for 10 minutes, and filtered. The resulting solid product is added to 200 mL of deionized water, and 0.35 g of the reduced carbon dots prepared in step 3) is added under stirring. Ultrasonic dispersion is performed for 45 minutes. The resulting mixture is transferred to a polytetrafluoroethylene-lined reactor, reacted at 140° C. for 5 hours, cooled to room temperature, centrifuged, washed with deionized water, and vacuum dried at 70° C. to constant weight to obtain the metal oxide-carbon-based material composite catalyst.

8. A hydrogen-powered electric bicycle using solid-state hydrogen storage as a hydrogen source, comprising a vehicle body, a hydrogen fuel cell system, and a drive system, wherein the hydrogen fuel cell system utilizes the high-performance solid-state hydrogen storage material described in any one of claims 1-7 to provide hydrogen to generate electrical energy, and the drive system utilizes the electrical energy provided by the hydrogen fuel cell system to provide driving force for the vehicle body.

9. The hydrogen-powered electric bicycle using solid-state hydrogen storage as a hydrogen source according to claim 8, characterized in that: The hydrogen fuel cell system includes a hydrogen storage bottle filled with the high-performance solid hydrogen storage material as described in any one of claims 1 to 7 for providing hydrogen, and a fuel cell for generating electrical energy using hydrogen.

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