A metal-modified graphene structure model in predicting the application of hydrogen storage materials

Abstract

A metal modified graphene structure model is applied to predict hydrogen storage materials, comprising a structure simulation unit, a simulation data unit, a preparation measurement unit, a data processing unit and a parameter feedback unit; the structure simulation unit includes a graphene base structure composed of carbon atoms and a plurality of modified structure models pre-prepared for metal modification of the graphene base, combined into hydrogen storage materials; the simulation data unit calculates the structure of H2 molecules adsorbed on the hydrogen storage materials and calculates the simulation hydrogen storage data; the preparation measurement unit actually prepares the hydrogen storage materials and measures the actual hydrogen storage data; when the actual hydrogen storage rate data is greater than or equal to the first threshold value, the data processing unit calculates the difference percentage of the actual hydrogen storage data and the simulation hydrogen storage data, and outputs the data difference degree; otherwise, an abnormal warning signal is output; when the data difference degree is less than or equal to the second threshold value, the parameter feedback unit outputs that the hydrogen storage data of the preparation measurement unit is qualified, otherwise, an abnormal warning signal is output and feedback is performed, and data optimization is performed.

Description

Technical Field

[0001] This invention relates to the field of carbon-based hydrogen storage technology, and more specifically, to the application of a metal-modified graphene structure model in predicting hydrogen storage materials. Background Technology

[0002] Finding new, pollution-free, and low-cost energy sources is a pressing issue for the world today. Hydrogen, one of the most abundant elements on Earth, is considered a new green energy source that can replace traditional fossil fuels and address the energy crisis and environmental pollution. While hydrogen production technology is relatively mature, hydrogen storage technology still needs further development. Traditional high-pressure gaseous hydrogen storage and cryogenic liquid hydrogen storage technologies are costly, difficult to transport, and pose explosion risks. Solid-state hydrogen storage, on the other hand, is attracting increasing attention from researchers due to its advantages such as large capacity, high safety, and simple hydrogen adsorption / desorption.

[0003] In recent years, two-dimensional material physical adsorption hydrogen storage technology has attracted widespread attention as an emerging hydrogen storage technology. Hydrogen is adsorbed onto the surface of a two-dimensional material in molecular form, and these molecules are connected to the substrate by van der Waals forces. Carbon-based materials, due to their advantages such as light weight, high porosity, and good electronic properties, have been extensively studied as hydrogen storage materials. The adsorption energy of H2 on the substrate should be in the range of -0.20 to -0.60 eV to ensure hydrogen adsorption / desorption under suitable operating conditions. Furthermore, the hydrogen storage rate should meet the requirements of the U.S. Department of Energy (DOE), reaching at least 5.5 wt%. However, the adsorption capacity of pristine carbon materials is typically low.

[0004] Therefore, the existing technology has problems and needs further improvement and development. Summary of the Invention

[0005] (I) Purpose of the invention: In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a metal-modified graphene structure model for predicting the application of hydrogen storage materials.

[0006] (II) Technical Solution: In order to solve the above technical problems, this technical solution provides a metal-modified graphene structure model for predicting the application of hydrogen storage materials, including a structure simulation unit, a simulation data unit, a preparation and measurement unit, a data processing unit and a parameter feedback unit.

[0007] The structural simulation unit includes a graphene substrate structure composed of carbon atoms and multiple prefabricated modified structural models that are metal-modified onto a graphene substrate. The structural simulation unit receives input data and matches the corresponding modified structural models to the input data. The matched modified structural models and graphene substrate structures are then combined to generate hydrogen storage materials.

[0008] The simulation data unit calculates the structure of H2 molecules adsorbed on the hydrogen storage material, calculates the simulated hydrogen storage data of the hydrogen storage material, and outputs it to the data processing unit.

[0009] The preparation and measurement unit actually prepares the hydrogen storage material, measures and stores the actual hydrogen storage data of the prepared hydrogen storage material, and outputs it to the data processing unit;

[0010] When the actual hydrogen storage rate is greater than or equal to the first threshold, the data processing unit calculates the percentage difference between the actual hydrogen storage data and the simulated hydrogen storage data and outputs the data difference degree; otherwise, the data processing unit outputs an abnormal warning signal.

[0011] When the data difference is less than or equal to the second threshold, the parameter feedback unit outputs that the hydrogen storage data of the preparation measurement unit is qualified; otherwise, it outputs an abnormal warning signal and feeds it back to the simulation data unit and the preparation measurement unit for data optimization until the data difference is less than or equal to the second threshold.

[0012] The modified structure model is formed by the adsorption of metal atoms on a Tri-G substrate through van der Waals interactions, with the metal atoms adsorbed at the center of the twelve rings of the Tri-G substrate.

[0013] The metal atoms are adsorbed on a Tri-G substrate, where the C=C bond length connecting two triangles in the Tri-G substrate remains unchanged, while the C=C bond length in the triangle increases.

[0014] The simulated H2 adsorption intensity data of the Tri-G substrate structure model and the K@Tri-G structure model are outside the energy range and cannot stably adsorb H2 molecules, thus they cannot be used as hydrogen storage materials.

[0015] The hydrogen storage capacity of the hydrogen storage material is reflected by hydrogen storage data, which includes hydrogen storage rate data and H2 desorption temperature data; H2 molecules are adsorbed at the center of the dodecagonal structure of the hydrogen storage material.

[0016] The hydrogen storage data is affected by temperature and pressure. The higher the temperature and pressure, the more stable the adsorption of H2. The amount of H2 adsorbed increases with the increase of pressure and tends to the same saturation value at different temperatures. When the pressure is constant, H2 will gradually desorb as the temperature increases.

[0017] Wherein, the data difference S represents the percentage difference between the actual hydrogen storage data measured by the preparation measurement unit and the simulated hydrogen storage data calculated by the simulation data unit.

[0018] .

[0019] Among them, Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures are highly efficient reversible hydrogen storage materials, and the Ca@Tri-G structure can even be used for room temperature hydrogen storage.

[0020] The first threshold and the second threshold are preset before the data is input to the structural simulation unit. Once the settings are successful, they cannot be changed during the operation of the entire hydrogen storage preparation system.

[0021] A metal-modified graphene structural model for predicting applications in hydrogen storage materials includes the following steps:

[0022] Step 1: Input the atomic number of the metal atoms. The structure simulation unit receives the input data, simulates the adsorption of metal atoms on the graphene substrate, matches the corresponding modified structure model, and generates hydrogen storage material.

[0023] Step 2: The simulation data unit calculates the structure of H2 molecules adsorbed on the hydrogen storage material, calculates the simulated hydrogen storage data of the hydrogen storage material, and outputs it to the data processing unit.

[0024] Step 3: The preparation and measurement unit actually prepares the hydrogen storage material, measures and stores the actual hydrogen storage data of the prepared hydrogen storage material, and outputs it to the data processing unit;

[0025] Step 4: The data processing unit analyzes and processes the simulated hydrogen storage data and the actual hydrogen storage data. When the actual hydrogen storage rate data is greater than or equal to the first threshold, the data processing unit outputs the data difference between the simulated hydrogen storage data and the actual hydrogen storage data to the parameter feedback unit; when the actual hydrogen storage rate data is less than the first threshold, the data processing unit outputs an abnormal warning signal.

[0026] Step 5: When all the data differences are less than or equal to the second threshold, the parameter feedback unit outputs that the hydrogen storage data of the preparation measurement unit is qualified; when any of the data differences is greater than the second threshold, the parameter feedback unit outputs an abnormal warning signal and feeds it back to the simulation data unit and the preparation measurement unit, repeating steps 2 to 5 to optimize the data until all the data differences are less than or equal to the second threshold.

[0027] (III) Beneficial effects: This invention provides a metal-modified graphene structure model for predicting the application of hydrogen storage materials. It theoretically simulates the structure of hydrogen storage materials and calculates the simulated hydrogen storage data for each structure. At the same time, it actually prepares metal-modified graphene hydrogen storage materials and measures the actual hydrogen storage data. It compares the simulated hydrogen storage data with the actual hydrogen storage data one by one and outputs the hydrogen storage data that meets the conditions. Otherwise, it issues an abnormal warning for optimization. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the application of a metal-modified graphene structure model of the present invention in predicting hydrogen storage materials.

[0029] Figure 2 It is the 2×2×1 structure of the Tri-G of this invention;

[0030] Figure 3 These are possible adsorption sites for the metal atom modification of the Tri-G structure in this invention;

[0031] Figure 4 This is an optimized 2×2×1 structure of Li@Tri-G in this invention;

[0032] Figure 5 This is an optimized 2×2×1 structure of Na@Tri-G in this invention;

[0033] Figure 6 It is an optimized 2×2×1 structure of the K@Tri-G of this invention;

[0034] Figure 7 This is an optimized 2×2×1 structure of Ca@Tri-G in this invention;

[0035] Figure 8 This is the electronic localization function diagram of the 2×2×1 structure of the Tri-G structure of this invention;

[0036] Figure 9 This is the electronic localization function diagram of the 2×2×1 structure of Li@Tri-G in this invention;

[0037] Figure 10 This is the electronic localization function diagram of the 2×2×1 structure of Na@Tri-G in this invention;

[0038] Figure 11 This is the electronic localization function diagram of the 2×2×1 structure of K@Tri-G in this invention;

[0039] Figure 12 This is the electronic localization function diagram of the 2×2×1 structure of Ca@Tri-G in this invention;

[0040] Figure 13 This is the Bader charge transfer diagram of metal atoms in Li / Na / K / Ca@Tri-G of this invention;

[0041] Figure 14 These are possible adsorption sites for H2 in the metal atom-modified Tri-G structure of this invention;

[0042] Figure 15 This is an occupancy rate-pressure-temperature diagram of hydrogen storage in Li@Tri-G of this invention;

[0043] Figure 16This is a diagram showing the occupancy rate-pressure-temperature of hydrogen storage in Na@Tri-G of this invention;

[0044] Figure 17 This is the occupancy rate-pressure-temperature diagram of hydrogen storage in Ca@Tri-G of this invention;

[0045] Figure 18 This is a flowchart illustrating the application of a metal-modified graphene structure model of the present invention in predicting hydrogen storage materials. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to preferred embodiments. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0047] The accompanying drawings are schematic diagrams of embodiments of the present invention. It should be noted that these drawings are for illustrative purposes only and are not drawn to scale, and should not be construed as limiting the actual scope of protection of the present invention.

[0048] This invention provides a metal-modified graphene structural model for predicting applications in hydrogen storage materials, such as... Figure 1 As shown, the system includes a structural simulation unit, a simulation data unit, a preparation and measurement unit, a data processing unit, and a parameter feedback unit. The structural simulation unit receives input data and performs simulations of the graphene substrate structure and multiple pre-set modified structural models with metal modifications to the graphene substrate. The simulation data unit calculates the simulated hydrogen storage data of the structural models simulated by the structural simulation unit. Simultaneously, the preparation and measurement unit actually prepares hydrogen storage materials, measures the actual hydrogen storage performance, and stores the data. The data processing unit calculates the percentage difference between the simulated hydrogen storage data calculated by the simulation data unit and the actual hydrogen storage data measured by the preparation and measurement unit for hydrogen storage materials whose actual hydrogen storage rate is greater than or equal to a first threshold, and outputs the data difference degree; otherwise, an abnormal signal warning is issued. When the data difference degree is less than or equal to a second threshold, the parameter feedback unit outputs that the hydrogen storage performance data of the preparation and measurement unit is qualified; otherwise, an abnormal warning signal is output and fed back to the simulation data unit and the preparation and measurement unit for data optimization until it is less than or equal to the second threshold.

[0049] The first threshold is the hydrogen storage rate standard stipulated by the U.S. Department of Energy, which should be greater than or equal to 5.5 wt%; the second threshold is calculated by subtracting the hydrogen storage data from the simulated data unit and the hydrogen storage data measured by the preparation measurement unit, and the percentage difference between the difference and the actual hydrogen storage data. .

[0050] The structural simulation unit includes the simulation of graphene substrate structure and the simulation of multiple preset modified structure models of graphene substrate with metal modification obtained from input data. In this embodiment, by inputting the atomic numbers of the four metal atoms Li, Na, K and Ca, the metal-modified graphene structure models are obtained and named Li@Tri-G, Na@Tri-G, K@Tri-G and Ca@Tri-G structure models, respectively.

[0051] Replacing each carbon atom in cubic diamond with a tetrahedral structural unit consisting of four carbon atoms creates a novel three-dimensional cubic crystal structure of carbon, called T-carbon. When T-carbon is located on the

[110] crystal plane, it is a planar two-dimensional porous carbon material, called tri-graphene (Tri-G). Figure 2 The diagram shows a 2×2×1 Tri-G substrate structure composed of triangles and twelve bodies. The Tri-G structure consists of six carbon atoms with a lattice constant a=b=5.19 Å. The C-C bonds within the triangles are sp bonds. 3 The hybrid single bond has a C=C bond length of d1 = 1.42 Å; the C=C bond connecting the two triangles is sp 3 The hybrid double bond has a C=C bond length of d2 = 1.35 Å.

[0052] Four metal-modified graphene structural models were named Li@Tri-G, Na@Tri-G, K@Tri-G, and Ca@Tri-G. All possible metal modification sites, including vacant sites (H1, H2), apical sites (T1), and bridging sites (B1, B2), are shown below. Figure 3 As shown.

[0053] The bonding strength between the metal atoms and the substrate is expressed as the bonding energy ( To describe, use formula (1) to calculate:

[0054] (1)

[0055] It is the total energy of the metal-modified Tri-G;

[0056] It is the energy of a single layer of Tri-G;

[0057] It is the energy of isolated metal atoms.

[0058] Known The lower the value, the easier it is for the metal atoms to adsorb onto the Tri-G substrate, and the more stable the adsorption of the metal atoms onto the Tri-G substrate.

[0059] However, the binding energy between the metal atoms and the substrate should be less than the cohesive energy between the metal atoms to avoid metal clustering, which would prevent the metal from adsorbing onto the Tri-G substrate. The cohesive energy of Li metal atoms is known to be -1.63 eV, Na metal atoms -1.11 eV, K metal atoms -0.93 eV, and Ca metal atoms -1.84 eV.

[0060] The binding energies of the metal atoms adsorbed on the Tri-G substrate according to formula (1) are shown in Table 1. The results show that the minimum binding energies of these four metal atoms adsorbed on the Tri-G substrate are all at the center of the twelve-ring. The atomic number of the metal atom is input into the structural simulation unit, which matches the corresponding modified structural model, such as... Figures 4-7 The figures shown are simulated Li@Tri-G, Na@Tri-G, K@Tri-G, and Ca@Tri-G modified structure models, respectively.

[0061]

[0062] Table 1. Binding energies (E) of Li, Na, K, and Ca adsorbed on Tri-G. b H1 and H2 represent the twelve-ring structure, the sites above the triangle. T1 is the apex site above the C atom, and B1 and B2 are the bridge sites above the C=C and C-C bonds, respectively.

[0063] As shown in Table 2, the C=C bond length d2 of the metal-modified Tri-G is 1.35 Å, while the C=C bond length d1 is increased to varying degrees.

[0064]

[0065] Table 2. Lattice constants and bond lengths of Tri-G, Li@Tri-G, Na@Tri-G, K@Tri-G and Ca@Tri-G.

[0066] When the metal is adsorbed at the center of the twelve-ring structure on the Tri-G substrate, the C-C bond length d1 increases to varying degrees. Therefore, it is necessary to understand the bonding patterns between the atoms after the metal atoms are adsorbed onto the Tri-G substrate. This invention calculates the electronic localization function (ELF) to understand the bonding relationships between atoms, such as... Figures 8-13 As shown.

[0067] It is known that when the localization degree is greater than 0.5, it is considered a covalent bond between atoms; otherwise, it is considered an ionic bond. Therefore, it can be concluded that all C-C bonds are covalent bonds. However, it is clear that the C-C bond strength of Tri-G before metal modification is significantly higher than that after metal modification, indicating that the addition of metal atoms weakens the C-C bond strength. Furthermore, there is no bonding in the region surrounding the metal atom, proving that there is no chemical bond between the metal atom and the surrounding C atoms. The metal atom is merely adsorbed onto the Tri-G matrix in the form of physical adsorption, and the metal atom and the Tri-G matrix are connected by van der Waals interactions.

[0068] The simulation data unit calculates simulated hydrogen storage data for the structural model of the structural simulation unit. This simulated hydrogen storage data includes simulated hydrogen storage rate data and simulated H2 desorption temperature data, and is output to the data processing unit. In this embodiment, the simulation data unit calculates simulated hydrogen storage data for the Li@Tri-G, Na@Tri-G, K@Tri-G, and Ca@Tri-G structural models of the structural simulation unit and outputs this data to the data processing unit.

[0069] The adsorption strength of the H2 molecules on the metal-modified Tri-G structure is expressed as the average adsorption energy ( ). To describe, calculate according to formula (2):

[0070] (2)

[0071] It is the total energy of n H2 molecules adsorbed on the metal-modified Tri-G;

[0072] It is the energy of metal atoms adsorbed on Tri-G;

[0073] It is the energy of isolated H2;

[0074] This represents the number of H2 molecules adsorbed.

[0075] Based on existing conclusions, when When the value is in the range of -0.60 eV to -0.20 eV, it is conducive to the adsorption of H2 molecules on Tri-G, while also facilitating their desorption.

[0076] like Figure 14 The diagram shows all possible adsorption sites for H2 molecules. The results indicate that in all structures, H2 molecules tend to adsorb at the center of the dodecagonal (H'1) structure.

[0077] For the adsorption of one H2 molecule, according to formula (2), the average adsorption energies of the Tri-G structural model and the K@Tri-G structural model are -0.19 eV and -0.17 eV, respectively, which exceed the energy range of -0.60 eV to -0.20 eV. Therefore, the Tri-G structural model and the K@Tri-G structural model cannot stably adsorb H2 molecules and are not suitable as hydrogen storage materials. The average adsorption energies of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models calculated according to formula (2) are shown in Table 3, all of which are within the reasonable range of -0.60 eV to -0.20 eV.

[0078]

[0079] Table 3 Adsorption energies (E) of H2 on Li@Tri-G, Na@Tri-G and Ca@Tri-G ads ).

[0080] Because Tri-G materials have many H , 2. Adsorption sites: Therefore, this embodiment further calculates the maximum adsorption quantity of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models to calculate the hydrogen storage rate. The results show that when the Li@Tri-G structural model adsorbs the 13th H2 molecule, the distance between one H2 molecule and the Li@Tri-G structural model is as high as 4.69 Å, far exceeding the standard of 4 Å. Therefore, it is impossible for all 13 H2 molecules to be stably adsorbed on the surface of the Li@Tri-G structural model. Therefore, another attempt was made to adsorb 12 H2 molecules onto the substrate. It was found that both the energy and distance met the standard. Therefore, it is considered that the Li@Tri-G structural model can adsorb 12 H2 molecules on one side, and the same applies to the Ca@Tri-G structural model, which can adsorb 12 H2 molecules on one side. The adsorption energy of the Na@Tri-G structural model when it adsorbs 7 H2 molecules is -0.20 eV. If more H2 molecules are adsorbed, the adsorption energy may be greater than -0.20 eV, and all H2 molecules may not be able to exist stably. Therefore, it is believed that the Na@Tri-G structural model can adsorb 7 H2 molecules on one side.

[0081] Next, considering the hydrogen storage capacity on both sides, this invention attempts to directly adsorb the same number of H2 molecules as the upper layer in the lower layer of the Tri-G substrate. The results show that the lower surface of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models can still stably adsorb the same number of H2 molecules as the upper layer. Therefore, the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models can stably adsorb 24, 14, and 24 H2 molecules, respectively.

[0082] The hydrogen storage capacity of the metal-modified Tri-G is defined as follows:

[0083] (3)

[0084] It is the mass of the total number of H2 molecules;

[0085] It is the quality of Tri-G with metal modification.

[0086] The simulated hydrogen storage rates of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models calculated according to formula (3) are 13.99%, 8.26%, and 12.77%, respectively, all of which are higher than the 5.5% standard set by the U.S. Department of Energy (DOE).

[0087] To investigate the practical application of the metal-modified Tri-G structure in hydrogen storage, the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures also need to be easily desorbed by H2 molecules. This invention determines the desorption temperature of H2 molecules adsorbed on the substrate based on the van Hoff equation. ), calculated according to formula (4):

[0088] (4)

[0089] It is the average adsorption energy of the metal-modified Tri-G structure;

[0090] It is the Boltzmann constant, with a value of 1.38 × 10⁻⁶. -23 J / K;

[0091] It is the entropy change from gaseous hydrogen to liquid, with a value of 75.44 J / mol·K;

[0092] It is the universal gas constant, with a value of 8.314 J / mol·K;

[0093] Balanced pressure Set to 1 atm, its value is 1.01325 × 10 5 Pa.

[0094] Desorption temperature ( The desorption temperature (T) is an important indicator for characterizing the reversible hydrogen storage capacity of materials at room temperature. As shown in Table 4, the desorption temperatures of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models are calculated according to formula (4).

[0095]

[0096] Table 4. Desorption temperatures (T) of nH2 (n=1~24) adsorbed on Li@Tri-G, Na@Tri-G and Ca@Tri-G, respectively. D ).

[0097] As shown in Table 4, the desorption temperature range of the Li@Tri-G structural model is 268.33 K to 459.99 K, with an average desorption temperature of 271.52 K. The desorption temperature range of the Na@Tri-G structural model is 255.55 K to 319.44 K, with an average desorption temperature of 273.44 K. The desorption temperature range of the Ca@Tri-G structural model is 281.11 K to 434.44 K, with an average desorption temperature of 305.07 K. The desorption temperatures of the three hydrogen storage materials, Li@Tri-G, Na@Tri-G, and Ca@Tri-G, are all within an adjustable temperature range and are all more than 8 times higher than the H2 critical temperature (33 K). These results indicate that the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures are highly efficient reversible hydrogen storage materials above 255 K. The average desorption temperature of the Li@Tri-G and Na@Tri-G structures is close to the freezing point, while the average desorption temperature of the Ca@Tri-G structure is close to room temperature.

[0098] However, in actual operation, since hydrogen storage performance is affected by pressure (p) and temperature (T), this embodiment introduces the occupancy number (…). To analyze the adsorption / desorption of H2, the occupancy number (OCN) was used. The actual temperature was analyzed according to formula (5). ) and pressure ( Thermodynamic properties of hydrogen molecules adsorbed on Tri-G:

[0099] (5)

[0100] This is the maximum number of H2 molecules that can be adsorbed.

[0101] It represents the amount of H2 adsorbed;

[0102] It is 1.38×10 -23 J / K;

[0103] The degeneracy of a configuration is represented by the total number of equivalent equilibrium configurations separated by a non-zero barrier. The contribution of phonons to entropy is negligible, therefore... Set to 1.

[0104] like Figures 15-17As shown, from left to right, the adsorption amounts of H2 molecules on the metal-modified Tri-G structures are 1 Pa, 10 Pa, 30 Pa, 50 Pa, and 100 Pa, respectively. The results indicate that the higher the temperature and pressure, the more stable the H2 adsorption. Clearly, the adsorption amount increases with increasing pressure and tends to the same saturation value at different temperatures. When the pressure is constant, the adsorption amount decreases with increasing temperature, and H2 molecules gradually desorb. The stable adsorption temperature range of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models is 100–200 K, and the desorption temperature range is 200–400 K. Therefore, the adsorption and desorption of H2 molecules on the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models can be adjusted by regulating the temperature.

[0105] In summary, based on the excellent theoretical hydrogen storage capacity and predicted thermodynamic desorption temperature of the Li@Tri-G and Na@Tri-G structures, the Li@Tri-G and Na@Tri-G structures are expected to become efficient reversible hydrogen storage media under adjustable temperatures, and the Ca@Tri-G structure can even be used for room temperature hydrogen storage.

[0106] Simultaneously, the preparation and measurement unit prepares the structure simulated by the structure simulation unit and measures the actual hydrogen storage data, outputting the data to the data processing unit for storage. Many preparation methods exist, as long as the metal atoms can be stably adsorbed at the dodecyl ring center of the Tri-G substrate; no specific limitations are imposed here. To facilitate data comparison by the data processing unit, the temperature and pressure measured for the actual hydrogen storage data are consistent with the temperature and pressure calculated by the simulation unit for the simulated hydrogen storage data. Correspondingly, the actual hydrogen storage data also includes actual hydrogen storage rate data and actual H2 desorption temperature data.

[0107] The hydrogen storage material prepared by the preparation and measurement unit should correspond one-to-one with the hydrogen storage material model simulated by the structure simulation unit, and the actual hydrogen storage data measured by the preparation and measurement unit should correspond one-to-one with the simulated hydrogen storage data calculated by the simulation data unit.

[0108] Since the Tri-G structure model and the K@Tri-G structure model calculated by the simulation data unit are outside the energy range and cannot stably adsorb H2 molecules, in this embodiment, H2 molecules are only adsorbed on the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures at 100 Pa and 298 K, and the hydrogen storage data of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures are measured respectively.

[0109] The data processing unit processes the actual hydrogen storage data of the hydrogen storage material measured by the preparation and measurement unit and the simulated hydrogen storage data of the hydrogen storage material calculated by the simulation data unit. If the actual hydrogen storage rate is greater than or equal to a first threshold, the data processing unit calculates the difference between the simulated hydrogen storage data and the actual hydrogen storage data, and outputs the percentage of the difference to the simulated hydrogen storage data calculated by the simulation data unit as the data difference degree to the parameter feedback unit. If the actual hydrogen storage rate is less than the first threshold, the data processing unit outputs an abnormal warning signal to the parameter feedback unit.

[0110] The hydrogen storage data includes hydrogen storage rate data of hydrogen storage materials and H2 desorption temperature data. The hydrogen storage rate data includes simulated hydrogen storage rate data and actual hydrogen storage rate data. The H2 desorption temperature data includes simulated H2 desorption temperature data and actual H2 desorption temperature data. The corresponding data difference also includes the difference in hydrogen storage rate data of hydrogen storage materials and the difference in H2 desorption temperature data.

[0111] The parameter feedback unit analyzes and processes the data difference degree output by the data processing unit. If all the data difference degrees are less than or equal to the second threshold, the parameter feedback unit outputs the hydrogen storage data simulated by the simulation data unit. If any of the data difference degrees is greater than the second threshold, the parameter feedback unit outputs an abnormal warning signal and feeds it back to the simulation data unit and the preparation measurement unit. The simulation data unit recalculates the simulated hydrogen storage data, and the preparation measurement unit remeasures the actual hydrogen storage data and recalculates the data difference degree until the data difference degree is less than or equal to the second threshold.

[0112] The first and second thresholds can be set and changed before the metal-modified graphene structure model of this invention is started to predict the application of hydrogen storage materials, that is, before the atomic number of the metal atoms is input into the structure simulation unit. Once the data is input and the preparation system is running, they cannot be changed. This is to prevent errors in the hydrogen storage data comparison and processing process caused by changing the first or second threshold during operation, thus preventing data errors.

[0113] A metal-modified graphene structural model is used to predict applications in hydrogen storage materials, such as... Figure 18 As shown, it includes the following steps:

[0114] Step 1: Input the atomic number of the metal atoms. The structure simulation unit receives the input data, simulates the adsorption of metal atoms on the graphene substrate, and matches the corresponding modified structure model to the input data to generate a hydrogen storage material.

[0115] Step 2: The simulation data unit calculates the structure of H2 molecules adsorbed on the hydrogen storage material, calculates the simulated hydrogen storage data of the hydrogen storage material, and outputs it to the data processing unit.

[0116] Step 3: The preparation and measurement unit actually prepares the hydrogen storage material, measures the actual hydrogen storage data of the prepared hydrogen storage material, and outputs it to the data processing unit;

[0117] Step 4: The data processing unit analyzes and processes the simulated hydrogen storage data and the actual hydrogen storage data. When the actual hydrogen storage rate data is greater than or equal to the first threshold, the data processing unit outputs the data difference between the simulated hydrogen storage data and the actual hydrogen storage data to the parameter feedback unit. When the actual hydrogen storage rate data is less than the first threshold, the data processing unit outputs an abnormal warning signal to the parameter feedback unit.

[0118] Step 5: When all the data differences are less than or equal to the second threshold, the parameter feedback unit outputs the hydrogen storage data simulated by the simulation data unit; when any of the data differences is greater than the second threshold, the parameter feedback unit outputs an abnormal warning signal and feeds it back to the simulation data unit and the preparation measurement unit. The simulation data unit recalculates the simulated hydrogen storage data, the preparation measurement unit remeasures the actual hydrogen storage data, and the data processing unit recalculates the data differences and performs analysis and comparison until the data differences are less than or equal to the second threshold.

[0119] The above description illustrates preferred embodiments of the present invention and helps those skilled in the art to more fully understand the technical solution of the present invention. However, these embodiments are merely illustrative and should not be construed as limiting the specific implementation of the present invention to these embodiments. For those skilled in the art, several simple deductions and modifications can be made without departing from the inventive concept, and all such modifications should be considered within the protection scope of the present invention.

Claims

1. A metal-modified graphene structural model for predicting applications in hydrogen storage materials, characterized in that, The graphene structural model is the Tri-G trigraphene structural model, which includes triangles and twelve rings; Compared to the trigraphene structure, the C=C bond length remains unchanged in the metal-modified graphene structural model, while the C=C bond length increases. This indicates that the metal atoms act on the twelve-ring center of the trigraphene structural model through van der Waals forces, thus obtaining the metal-modified graphene structural model. The metal atoms include four types: Li, Na, K, and Ca. The resulting metal-modified graphene structural models are Li@Tri-G, Na@Tri-G, K@Tri-G, and Ca@Tri-G. The binding energy between the metal atoms and the trigraphene structure is calculated. , It is the total energy of the metal-modified Tri-G; It is the energy of a single layer of Tri-G; It is the energy of isolated metal atoms; The calculations showed that the minimum binding energy of the four metal atoms adsorbed on the Tri-G substrate was all at the center of the twelve ring, thus obtaining the predicted hydrogen storage material. Calculate and predict the average adsorption energy of H2 molecules in a metal-modified graphene structure model for hydrogen storage materials. , It is the total energy of n H2 molecules adsorbed on the metal-modified Tri-G; It is the energy of metal atoms adsorbed on Tri-G; It is the energy of isolated H2; The number of H2 molecules adsorbed; in all structures, H2 molecules tend to adsorb at the center of the dodecagon; The average H2 adsorption energies of the Tri-G substrate structure model and the K@Tri-G structure model exceed -0.60 eV to -0.20 eV, indicating that they cannot stably adsorb H2 molecules and are therefore unsuitable as hydrogen storage materials. In contrast, the average H2 adsorption energies of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structure models are all within the range of -0.60 eV to -0.20 eV, making them suitable as hydrogen storage materials. The maximum adsorption quantity of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models is calculated to determine the hydrogen storage rate. , It is the mass of the total number of H2 molecules; The mass of the metal-modified Tri-G is given; the simulated hydrogen storage rates of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models are 13.99%, 8.26%, and 12.77%, respectively. The desorption temperature of H2 molecules adsorbed on the substrate was determined using the van Hoff equation. The desorption temperature range of the Li@Tri-G structure model is 268.33 K to 459.99 K, with an average desorption temperature of 271.52 K; the desorption temperature range of the Na@Tri-G structure model is 255.55 K to 319.44 K, with an average desorption temperature of 273.44 K; and the desorption temperature range of the Ca@Tri-G structure model is 281.11 K to 434.44 K, with an average desorption temperature of 305.07 K. This indicates that the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structures are highly efficient reversible hydrogen storage materials above 255 K. In practical operation, considering the effects of temperature and pressure, further calculations using the occupational factor... Analyze actual temperature and pressure Thermodynamic properties of H2 molecules adsorbed on Tri-G , This is the maximum number of H2 molecules that can be adsorbed. It represents the amount of H2 adsorbed; It is 1.38×10 -23 J / K; The degeneracy of the configuration is indicated; the higher the temperature and pressure, the more stable the adsorption of H2; the adsorption amount increases with increasing pressure and tends to the same saturation value at different temperatures. When the pressure is constant, the adsorption amount decreases with increasing temperature, and H2 molecules gradually desorb; the stable adsorption temperature range of the Li@Tri-G, Na@Tri-G, and Ca@Tri-G structural models is 100~200K, and the desorption temperature range is 200~400K; the Li@Tri-G and Na@Tri-G structures are reversible hydrogen storage media at adjustable temperatures, and the Ca@Tri-G structure can even be used for hydrogen storage at room temperature.

Images