Method for calculating hydrogen adsorption of graphite diyne loaded transition metal based on first principle

Abstract

The invention designs a method for calculating hydrogen adsorption of graphite diyne loaded transition metals based on a first principle, geometric configurations of four graphite diyne loaded transition metals (Ni, Fe, Mo and Ru) are calculated based on the first principle, and the strength of chemical bonds formed by the four graphite diyne loaded transition metals and carbon atoms close to the four graphite diyne loaded transition metals is calculated to test the structural stability of the catalyst. And constructing a hydrogen adsorption model, carrying out geometric optimization on the model, and determining a hydrogen adsorption stable structure. Meanwhile, a wave function file during hydrogen adsorption is generated, a wave function is analyzed through Multiwfn software, the strength of chemical bonds formed by combination of metal elements and hydrogen is calculated and used for evaluating the combination mode of hydrogen and a catalyst, finally, the adsorption energy of hydrogen adsorption is calculated, and the adsorption condition of hydrogen is evaluated in combination with the strength of the chemical bonds. The invention is suitable for the design of a hydrogen adsorption catalyst, hydrogen is activated, energy required by hydrogen decomposition is reduced, the cost is saved, and meanwhile, the experiment direction can be guided.

Description

Technical Field

[0001] The invention relates to the technical field of electrical digital data processing, and in particular to a method for calculating the adsorption of hydrogen by transition metal loaded with graphdiyne based on first principles. Background Art

[0002] Single-atom catalysts are heterogeneous catalysts in which metal atoms are highly dispersed on a carrier. This material has attracted increasing attention due to its uniform catalytic active sites and maximum atomic utilization. In addition, its uniform catalytic activity makes it easier to study its properties and mechanisms.

[0003] Graphdiyne is a two-dimensional layered material composed of sp hybridized and sp 2 The crystal composed of hybridized carbon atoms has a highly conjugated porous structure, good conductivity and controllable electronic structure. Due to its uniform porous structure, it becomes one of the best carriers for single-atom catalysts. The single-atom catalysts composed of it are involved in various fields, such as CO oxidation, carbon dioxide reduction, hydrogenation, nitrogen reduction reaction, oxygen reduction reaction, etc. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the adsorption of hydrogen by transition metals supported on graphdiyne based on first principles, to optimize the structure of the catalyst, to test its stability, to analyze its electronic structure and to evaluate the performance of hydrogen adsorption, so as to provide a theoretical basis for catalyst design.

[0005] The present invention designs a method for calculating the adsorption of hydrogen by transition metals loaded on graphene diyne based on the first principles, obtains the geometric configuration of four transition metals (Ni, Fe, Mo, Ru) loaded on graphene diyne based on the first principles calculation, calculates the chemical bond strength formed by the four metals loaded on graphene diyne and the carbon atoms close to them to test the stability of the catalyst structure, constructs a model for the adsorption of hydrogen, performs geometric optimization on the model, and determines the stable structure of the adsorbed hydrogen. At the same time, a wave function file is generated when hydrogen is adsorbed, and the wave function is analyzed using Multiwfn software to calculate the strength of the chemical bond formed by the metal element and hydrogen, which is used to evaluate the combination mode of hydrogen and the catalyst, and finally calculates the adsorption energy of the adsorbed hydrogen, and evaluates the adsorption of hydrogen in combination with the chemical bond strength. The present invention is suitable for the design of hydrogen adsorption catalysts, activates hydrogen, reduces the energy required for hydrogen decomposition, and is used to save costs, and can guide the direction of experiments at the same time.

[0006] The method comprises the following steps: (1) Obtain the .cif file of the graphdiyne unit cell structure. The unit cell file is obtained from the MaterialsProject crystal database. Convert the .cif file into a .gjf file, expand the graphdiyne cell into a 2*2*1 supercell, and name it supercell.gjf; (2) Use supercell.gjf to generate the test.inp file and perform the cutoff energy and K-point convergence test on graphdiyne; (3) Generate opt.inp file using supercell.gjf, use CP2K software to optimize the structure of 2*2*1 supercell of graphdiyne, and generate optimized .gjf file through the obtained .restart file, which is the optimized stable structure configuration; (4) Construct structural models of Ni, Fe, Mo, and Ru loaded onto a 2*2*1 supercell of graphdiyne, generate .inp files, optimize the four structures, and perform energy calculations on the optimized structures. In the output file, the energy of the 2*2*1 supercell of graphdiyne loaded with four different metals is obtained, and the wave function .molden file is obtained; (5) Analyze the wave function .molden file obtained in step 4, calculate the Mayer bond order, and display it using drawing software; (6) Constructing a structural model of graphdiyne loaded with four different metals and adsorbing hydrogen, generating a .inp file, optimizing the structure, obtaining the stable configuration of graphdiyne loaded with four different metals and adsorbing hydrogen through the output file, and performing energy calculation on the optimized structure, obtaining the final energy of the four structures in the output file and obtaining the wave function .molden file; (7) Calculate the energy of a hydrogen molecule and then calculate the adsorption energy of hydrogen; (8) Analyze the wave function .molden file obtained in step 5, calculate the Mayer bond order, and display it using drawing software; (9) In step 2, the cutoff energy test result is 400Ry, and the k point of 221 is selected after the K point test; (10) In step 4, a 15 angstrom vacuum region is left above the model when constructing the model, and the loaded metal is a single atom, constituting a single atom catalyst; (11) In step 5, the wave function is analyzed using Multiwfn software; (12) In step 6, a 15 angstrom vacuum region was left above the model when constructing the model; (13) In step 7, the adsorption energy is calculated as E ads =E tot -E adsorbate -E catalysts，Where E ads is the adsorption energy, E tot is the total energy after hydrogen adsorption, E adsorbate is the energy of hydrogen, E catalysts Loading single metal atom energy for graphdiyne; (14) In step 8, the wave function was analyzed using Multiwfn software and plotted using VMD.

[0007] Beneficial Effects Based on the first-principles calculation method of graphdiyne-loaded transition metal adsorption of hydrogen, a single-atom catalyst is designed from the perspective of theoretical calculation to activate hydrogen, decompose hydrogen into single hydrogen radicals, provide a hydrogen source, and provide a theoretical basis for the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a flow chart of the method of the present invention; Figure 2 The structural diagram of graphdiyne loaded with four metals in the present invention; Figure 3 The bond order analysis diagram of four metals loaded on graphdiyne in the present invention; Figure 4 The four structures of the present invention are hydrogen adsorption structure diagrams; Figure 5 is a histogram of adsorption energy in the present invention; Figure 6 It is the bond order analysis diagram of hydrogen adsorption of four structures in the present invention. DETAILED DESCRIPTION

[0009] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: (1) Obtain the .cif file of the graphene primitive cell structure, convert the .cif file into a .gjf file, and expand the graphene primitive cell into a 2*2*1 supercell named supercell.gjf; (2) Use supercell.gjf to generate the test.inp file, and perform the cutoff energy and K-point convergence test on graphdiyne. The cutoff energy test result is 55Ry, and the K-point of 221 is selected after the K-point test; (3) Use supercell.gjf to generate opt.inp file, optimize the structure of the 2*2*1 supercell of graphene diyne, and obtain the stable configuration of the 2*2*1 supercell of graphene diyne through the information in the output file; (4) Construct structural models in which Ni, Fe, Mo, and Ru are loaded onto a 2*2*1 supercell of graphdiyne, respectively, leaving a 15 angstrom vacuum region on top. The loaded metal is a single atom, forming a single atom catalyst, and generate a .inp file. Optimize the four structures and calculate the energy of the optimized structures. The energy of the 2*2*1 supercell of graphdiyne loaded with four different metals is obtained in the output file, and the wave function .molden file is obtained; (5) Analyze the wave function .molden file obtained in step (4), calculate the Mayer bond order, and display it using drawing software; (6) constructing a structural model of graphdiyne loaded with four different metals and adsorbing hydrogen, leaving a 15 angstrom vacuum area above the model when constructing the model, generating a .inp file, optimizing the structure, obtaining the stable configuration of graphdiyne loaded with four different metals and adsorbing hydrogen through the output file, and performing energy calculation on the optimized structure, obtaining the final energy of the four structures in the output file and obtaining the wave function .molden file; (7) Calculate the energy of a hydrogen molecule, and then calculate the adsorption energy of hydrogen. The formula for calculating the adsorption energy is E ads =E tot -E adsorbate -E catalysts， Where E ads is the adsorption energy, E tot is the total energy after hydrogen adsorption, E adsorbate is the energy of hydrogen, E catalysts Loading single metal atom energy for graphdiyne; (8) Analyze the wave function .molden file obtained in step (6), calculate the Mayer bond order, and display it using VMD software; (9) In step (4), the optimized stable configuration is as follows Figure 2 , the four different metals all stay at one corner of GDY. By comparing GDY monomer and GDY loaded with single metal atoms, it can be observed that the four metals will cause GDY to deform to different degrees; (10) In step (5), based on the calculated data, a bond order diagram is drawn as follows: Figure 3 . Figure 3 The direct bonding relationship between the original graphene and the single metal atom after loading metal elements was demonstrated, reflecting the adsorption strength and structural stability between metal atoms and graphene. Among them, graphene loaded with Ru atoms is relatively stable. (11) In step (6), the specific configuration of adsorbed hydrogen is calculated as follows: Figure 4 As shown; (12) In step (7), the adsorption energy of hydrogen is calculated as Figure 5As shown, the four configurations of Ru, Fe, Mo, and Ni are negative values, indicating that the adsorbed hydrogen is chemically adsorbed and the hydrogen is activated; (13) In step (8), the bond order analysis is shown in Figure (6). Through the bond order analysis, it is inferred that the adsorption of hydrogen by Ru, Fe, Mo, and Ni is chemical adsorption, which is consistent with the adsorption energy analysis results.

Claims

1. A method for calculating the adsorption of hydrogen by transition metals on graphdiyne based on first principles, characterized in that: Follow the steps below to implement it: (1) Obtain the .cif file of the graphene primitive cell structure, convert the .cif file into a .gjf file, and expand the graphene primitive cell into a 2*2*1 supercell named supercell.gjf; (2) Use supercell.gjf to generate the test.inp file and perform the cutoff energy and K-point convergence test on graphdiyne; (3) Use supercell.gjf to generate opt.inp file, optimize the structure of the 2*2*1 supercell of graphene diyne, and obtain the stable configuration of the 2*2*1 supercell of graphene diyne through the information in the output file; (4) Construct structural models of Ni, Fe, Mo, and Ru loaded onto a 2*2*1 supercell of graphdiyne, generate .inp files, optimize the four structures, and perform energy calculations on the optimized structures. In the output file, the energy of the 2*2*1 supercell of graphdiyne loaded with four different metals is obtained, and the wave function .molden file is obtained; (5) Analyze the wave function .molden file obtained in step (4), calculate the Mayer bond order, and display it using drawing software; (6) Constructing a structural model of graphdiyne loaded with four different metals and adsorbing hydrogen, generating a .inp file, optimizing the structure, obtaining the stable configuration of graphdiyne loaded with four different metals and adsorbing hydrogen through the output file, and performing energy calculation on the optimized structure, obtaining the final energy of the four structures in the output file and obtaining the wave function .molden file; (7) Calculate the energy of a hydrogen molecule and then calculate the adsorption energy of hydrogen; (8) Analyze the wave function .molden file obtained in step (6), calculate the Mayer bond order, and display it using drawing software.

2. The method for calculating the adsorption of hydrogen by transition metals supported on graphdiyne based on first principles according to claim 2, characterized in that: In step (2), the cutoff energy test result is 400Ry, and after the K point test, a k point of 221 is selected.

3. The method for calculating hydrogen adsorption by transition metal supported on graphdiyne based on first principles according to claim 2, characterized in that: In step (4), a vacuum region of 15 angstroms is left above the model when the model is constructed, and the loaded metal is a single atom, constituting a single atom catalyst.

4. The method for calculating hydrogen adsorption by transition metal supported on graphdiyne based on first principles according to claim 2, characterized in that: In step (5), the wave function is analyzed using Multiwfn software.

5. The method for calculating the adsorption of hydrogen by transition metals supported on graphdiyne based on first principles according to claim 2, characterized in that: In step (6), a 15 angstrom vacuum region is left above the model when the model is constructed.

6. The method for calculating hydrogen adsorption by transition metal supported on graphdiyne based on first principles according to claim 2, characterized in that: In step 7, the adsorption energy is calculated as E ads =E tot -E adsorbate -E catalysts， Where E ads is the adsorption energy, E tot is the total energy after hydrogen adsorption, E adsorbate is the energy of hydrogen, E catalysts Loading single metal atom energy to graphdiyne.

7. The method for calculating hydrogen adsorption by transition metal supported on graphdiyne based on first principles according to claim 2, characterized in that: In step (8), the wave function is analyzed using Multiwfn software and plotted using VMD.

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