Method for calculating CO2 adsorption of graphite diyne loaded transition metal based on first principle

Abstract

The invention designs a method for calculating CO2 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 CO2 adsorption model, carrying out geometric optimization on the model, and determining a CO2 adsorption stable structure. Meanwhile, a wave function file during CO2 adsorption is generated, a wave function is analyzed through Multiwfn software, the strength of chemical bonds formed by combination of metal elements and CO2 is calculated and used for evaluating the combination mode of CO2 and a catalyst, finally, the adsorption energy of CO2 adsorption is calculated, and the adsorption condition of CO2 is evaluated in combination with the strength of the chemical bonds. According to the design of the CO2 conversion catalyst, CO2 is activated, energy needed by CO2 conversion 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 CO2 by graphdiyne loaded with transition metals based on first principles. Background Art

[0002] Human activities around the world have produced a large amount of greenhouse gas carbon dioxide, leading to rapid global warming. According to relevant reports and predictions, in the 21st century, due to the emission of greenhouse gases such as carbon dioxide, the global temperature will rise by 0.3-1.7℃ to 2.6-4.8℃.

[0003] The use of cleaner fuels is becoming a global focus. Natural gas is a clean and efficient fossil fuel. However, natural gas in nature can hardly meet the large demand of human beings. In order to solve environmental and energy problems, the methanation of carbon dioxide has received widespread attention. Since carbon dioxide is extremely stable and methanation is an 8-electron transfer process, the reaction process requires extremely high activation energy. In order to save energy, the use of catalysts in the reaction process is essential. In recent years, in order to develop high-efficiency catalysts, single-atom catalysts have entered people's field of vision.

[0004] 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.

[0005] 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 of single-atom catalysts. The single-atom catalysts composed of it are involved in various fields, such as the oxidation of carbon monoxide, the reduction of carbon dioxide, hydrogenation, nitrogen reduction reaction, oxygen reduction reaction, etc. In recent years, significant progress has been made in the reduction of carbon dioxide by single metal atom catalysts supported by graphdiyne. Summary of the invention

[0006] The purpose of the present invention is to provide a method for calculating the adsorption of carbon dioxide by transition metal supported on graphdiyne based on first principles, optimize the structure of the catalyst, test its stability, analyze its electronic structure and evaluate its performance in adsorbing carbon dioxide, so as to provide a theoretical basis for the design of carbon dioxide conversion catalysts.

[0007] The technical solution adopted by the present invention is a method for calculating the adsorption of carbon dioxide by transition metals loaded on graphdiyne based on first principles. The geometric configuration of four transition metals (Ni, Fe, Mo, Ru) loaded on graphdiyne is calculated based on first principles, the partial wave state density and bond order of the four metals loaded on graphdiyne are calculated to verify the structural stability, and the configurations of carbon dioxide adsorbed by the four structures are calculated, the adsorption energy of carbon dioxide is calculated, and the bond order between the metal and carbon dioxide is analyzed to determine the adsorption of carbon dioxide.

[0008] 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 carbon dioxide adsorbed by graphdiyne loaded with four different metals, generating a .inp file, optimizing the structure, obtaining the stable configuration of carbon dioxide adsorbed by graphdiyne loaded with four different metals 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 carbon dioxide molecule and then calculate the adsorption energy of carbon dioxide; (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 was analyzed using Multiwfn software and plotted using Origin; (12) In step 6, a 15 Å 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 adsorption of carbon dioxide, E adsorbate is the energy of carbon dioxide, 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.

[0009] The beneficial effect of the present invention is that based on the first principles calculation method of graphdiyne loaded transition metal adsorption of carbon dioxide, a single atom catalyst is designed from the perspective of theoretical calculation to activate carbon dioxide and reduce the energy required for converting carbon dioxide into usable energy products, thereby providing a theoretical basis for the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 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 structural diagram of carbon dioxide adsorption of four structures in the present invention; Figure 5 is a histogram of adsorption energy in the present invention; Figure 6 This is a bond order analysis diagram of the adsorption of carbon dioxide by the four structures in the present invention. DETAILED DESCRIPTION

[0011] 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, expand the graphene primitive 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. 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 PDOS, and display them using drawing software; (6) constructing a structural model of carbon dioxide adsorbed by graphdiyne loaded with four different metals, 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 carbon dioxide adsorbed by graphdiyne loaded with four different metals 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 carbon dioxide molecule, and then calculate the adsorption energy of carbon dioxide. The calculation formula for 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 adsorption of carbon dioxide, E adsorbate is the energy of carbon dioxide, 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, a bond order diagram is drawn based on the calculated data, such as Figure 3 , Figure 3 The direct bonding relationship between the original graphene and the single metal atom after loading a single metal element was demonstrated, reflecting the adsorption strength and structural stability between the metal atom and graphene. Among them, graphene loaded with Ru atoms is relatively stable. (11) In step 6, the specific configuration of adsorbed carbon dioxide is calculated as follows Figure 4 As shown; (12) In step 7, the adsorption energy of carbon dioxide is calculated as Figure 5 As shown, the four configurations Ru, Fe, and Mo have negative values, indicating that the adsorption of carbon dioxide is chemical adsorption, which activates carbon dioxide, while Ni is physical adsorption and cannot activate carbon dioxide; (13) In step 8, the bond order analysis is as follows Figure 6 As shown in the figure, through the analysis of bond order, it is inferred that the adsorption of carbon dioxide by Ru, Fe, and Mo is chemical adsorption, and that by Ni is physical adsorption, which is consistent with the results of adsorption energy analysis.

Claims

1. A method for calculating the adsorption of carbon dioxide by transition metals loaded on graphdiyne based on first principles, characterized in that: The CP2K software was used to obtain the geometric configurations of four transition metals (Ni, Fe, Mo, and Ru) loaded on graphdiyne. The partial wave state density and bond order of the four metals loaded on graphdiyne were calculated to verify the structural stability. The configurations of the four structures adsorbing carbon dioxide were calculated, the adsorption energy of carbon dioxide was calculated, and the bond order between the metal and carbon dioxide was used to determine the adsorption of carbon dioxide.

2. The method for calculating the adsorption of carbon dioxide by transition metal supported on graphdiyne based on first principles according to claim 1, characterized in that: Follow the steps below to implement it: (1) Obtain the structure file of the graphene diyne primitive cell in the .cif format, convert the .cif file into a .gjf file, and expand the graphene diyne 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 PDOS, and display them using drawing software; (6) Constructing a structural model of carbon dioxide adsorbed by graphdiyne loaded with four different metals, generating a .inp file, optimizing the structure, obtaining the stable configuration of carbon dioxide adsorbed by graphdiyne loaded with four different metals 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 carbon dioxide molecule and then calculate the adsorption energy of carbon dioxide; (8) Analyze the wave function .molden file obtained in step (6), calculate the Mayer bond order, and display it using drawing software.

3. The method for calculating the adsorption of carbon dioxide by transition metals loaded 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.

4. The method for calculating the adsorption of carbon dioxide 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.

5. The method for calculating carbon dioxide 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 and plotted using Origin.

6. The method for calculating the adsorption of carbon dioxide by transition metal 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.

7. The method for calculating carbon dioxide 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 adsorption of carbon dioxide, E adsorbate is the energy of carbon dioxide, E catalysts Loading single metal atom energy for graphdiyne.

8. The method for calculating carbon dioxide 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.

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