Method for analyzing adsorption effect and bonding strength of C4F7N molecule at pyridyl transition metal monatomic site

Abstract

The invention provides a method for analyzing the adsorption effect and bonding strength of C4F7N molecules at a pyridyl transition metal monatomic site, and aims to solve the problem that the existing theory cannot reflect the surface bonding condition of the C4F7N molecules after adsorption at a material surface active site. The method specifically comprises the following steps: constructing microstructures of different pyridyl transition metal single atoms and C4F7N molecules by using atomic modeling software; the adsorption structure, the adsorption energy, the van der Waals force ratio, the charge transfer and the like of the C4F7N molecule at the pyridyl transition metal monatomic site are calculated through the density functional theory; calculating a crystal orbit Hamiltonian layout function between a pyridyl transition metal single atom and a C4F7N molecule; the chemical bond strength between the pyridyl transition metal and the C4F7N molecule is analyzed, and the interaction mechanism of the pyridyl transition metal single atom and the C4F7N molecule is disclosed. The method is used for systematically analyzing physical and chemical adsorption characteristics of gas molecules at transition metal monatomic sites on one hand, and providing theoretical reference for research and development of C4F7N adsorption and gas-sensitive sensing materials on the other hand.

Description

Technical Field

[0001] The present invention belongs to the field of computational material chemistry technology, and specifically relates to a theoretical method for analyzing the adsorption and bonding strength of C4F7N molecules on pyridyl transition metal single atom sites. Background Art

[0002] Sulfur hexafluoride (SF6) is a widely used gas insulation medium, and its Global Warming Potential (GWP) is 23,500 times that of CO2.

[0003] Perfluoroisobutyronitrile (C4F7N) has excellent insulation performance and a GWP value of only 2100, making it the most promising environmentally friendly insulating gas. However, during the production and long-term operation of gas-insulated electrical equipment, leakage of gas insulating medium is inevitable, which not only weakens the insulation performance of the equipment, but also leads to potential biosafety risks. It is necessary to explore low-cost, high-performance low-concentration C4F7N gas sensors and related technologies in a targeted manner to accurately monitor the concentration of C4F7N in the working environment, which is crucial to ensuring the normal operation of power transmission and transformation equipment and the health and safety of operation and maintenance personnel.

[0004] At present, the methods for detecting low-concentration C4F7N mainly include gas chromatography and optical detection. Gas chromatography has high accuracy, but its equipment is bulky and the detection time is long, which cannot meet the needs of actual scenarios. The optical measurement method has a faster response and better linearity. However, its gas cell module is large in size, high in power and high in cost, so it is difficult to achieve miniaturization and large-scale layout. In recent years, semiconductor gas sensors have been widely used in the field of monitoring low-concentration and trace gases due to their advantages such as small size, low cost and long life. However, the gas-sensitive materials widely used at this stage, such as metal oxides, graphene, etc., lack active sites for C4F7N gas on the surface, resulting in low sensitivity and long response recovery time. Therefore, it is necessary to regulate the surface active sites of gas-sensitive materials to enhance the adsorption performance of C4F7N.

[0005] The pyridyl transition metal single atom structure has good catalytic performance, and its activity can be regulated by changing the central metal element and the coordination environment. In this context, the present invention designs a series of potential C4F7N adsorption and gas-sensitive materials based on the pyridyl transition metal single atom structure through density functional theory simulation, revealing the physical and chemical interaction mechanism between the two. Summary of the invention

[0006] The present invention aims at a theoretical method for analyzing the adsorption and bonding strength of C4F7N molecules on pyridyl transition metal single atom sites. By establishing a microscopic theoretical model of pyridyl transition metal single atom structure adsorbing C4F7N, calculating parameters such as adsorption energy, van der Waals force ratio, charge transfer and COHP, the physicochemical interaction between different pyridyl transition metal single atom sites and C4F7N molecules is obtained, the interaction mechanism is explored more accurately, and the problem that the existing technology is difficult to accurately obtain adsorption active sites for C4F7N is solved.

[0007] A theoretical method for analyzing the adsorption and bonding strength of C4F7N molecules on pyridyl transition metal single atom sites. The specific process is as follows:

[0008] Step S1: using atomic modeling software to construct the microstructure of the pyridyl transition metal single atom site and the C4F7N molecular microstructure;

[0009] Step S2: Using DMol 3 The module calculates the adsorption structure, adsorption energy, van der Waals force ratio and charge transfer of C4F7N molecules on pyridyl transition metal single atom sites;

[0010] Step S3: Based on the adsorption structure in S2, DMol 3 The module calculates the COHP and its integral value between the pyridyl transition metal single atom and the C4F7N molecule;

[0011] Step S4: Based on the adsorption energy, van der Waals force ratio, charge transfer in S2 and the COHP calculation results in S3, the chemical bond strength between the pyridyl transition metal single atom and the C4F7N molecule is analyzed to reveal the interaction mechanism between the two;

[0012] Furthermore, in step S1, the pyridyl transition metal single atom site structure is: a single transition metal atom in the center, and four nitrogen (N) atoms coordinated around it form a pyridine ring, forming a pyridyl TM-N4 structure. The pyridyl TN-N4 structure is surrounded by hexagonal graphene-like carbon atoms, surrounded by hydrogen atoms to prevent the formation of dangling bonds.

[0013] Furthermore, in step S2, the transition metal is set as the adsorption site of the gas molecule, the adsorption direction is that the C≡N triple bond in the C4F7N molecule is perpendicular to the transition metal atom and the N atom is downward, and the distance between the transition metal atom and the N atom is to Based on density functional theory, the initial adsorption structure was geometrically optimized. Geometric optimization was selected and the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional in the Generalized Gradient Approximation (GGA) was selected. The geometric optimization convergence standard was set, and the energy convergence standard was 1×10 -6 Ha, the maximum atomic force is The maximum displacement distance is

[0014] Furthermore, in step S2, the pyridyl transition metal single atom structure and the C4F7N molecule without adsorbed C4F7N molecule are optimized according to the same geometric optimization convergence standard to obtain the energy of the two. The adsorption energy of the C4F7N molecule on the pyridyl transition metal single atom site is calculated using the following formula:

[0015]

[0016] Where E TM-N4 / C4F7N is the total energy after optimization of pyridyl transition metal single atom adsorption on C4F7N, E TM-N4 is the total energy of the optimized pyridyl transition metal single atom TM-N4 structure, E C4F7N is the total energy of the optimized C4F7N molecule. E a The calculations were performed with and without "Grimme" checked to obtain the adsorption energies corrected for van der Waals forces and those without van der Waals force correction. The calculation process of the van der Waals force fraction is as follows:

[0017]

[0018] Where R is the proportion of van der Waals force, E a(noVDW) is the adsorption energy without considering the van der Waals correction, E a(VDW) In order to consider the adsorption energy when van der Waals correction is taken into account, the charge transfer between the pyridyl transition metal atom and C4F7N is calculated using the Hirshfeld method: 3 In the electronic structure calculation of the module, check Population analysis to obtain the Hirshfeld charge of each atom, add up the charge of each atom in the C4F7N molecule, and calculate the charge transfer between the pyridyl transition metal atom and C4F7N.

[0019] Further, in step S3, the COHP and its integral value between the pyridyl transition metal single atom and the C4F7N molecule are calculated according to the following method, and the specific process is as follows:

[0020] For the optimized adsorption structure, in DMol 3 In the module for electronic structure calculation, check Calculate crystal orbital populations in Density ofstate, set the N atom and the pyridyl-centered transition metal atom in C4F7N as COHP objects, and calculate the COHP value of TM-N. Based on the COHP calculation results, make a -COHP curve of C4F7N at different pyridyl transition metal single atom sites, and integrate the curve from -∞ to 0:

[0021]

[0022] Where -ICOHP is the integral value and E is the energy value.

[0023] Further, in the step S4, by comparing the adsorption energy of different pyridyl transition metal single atom structures, the adsorption strength of C4F7N at different pyridyl transition metal single atom sites is evaluated, and the size of the chemical adsorption effect is evaluated in combination with the proportion of van der Waals force. The higher the proportion of van der Waals force, the more dominant the physical adsorption is, and the weaker the chemical adsorption effect is. The characteristics of gaining and losing electrons after adsorption of C4F7N by pyridyl transition metal single atom sites are evaluated by comparing the size of charge transfer. The charge transfer is positive, indicating that C4F7N acts as an electron donor, and negative indicates that C4F7N obtains electrons. Compare the -ICOHP values ​​between different pyridyl transition metal single atom sites and C4F7N to further evaluate the strength of the chemical bond between the two. Generally speaking, the larger the -ICOHP, the stronger the chemical bond between C4F7N and the transition metal atom. By analyzing the physicochemical adsorption and bonding characteristics of the above-mentioned C4F7N at different pyridyl transition metal single atom sites, the interaction mechanism of the two at the microscopic level is revealed.

[0024] Furthermore, the atomic modeling software adopts the Visualization module of Materials Studio.

[0025] Beneficial effects of the present invention:

[0026] Compared with the prior art, the present invention has the following significant advantages:

[0027] (1) The present invention calculates and screens pyridyl transition metal single atom structures for the adsorption and detection of C4F7N based on density functional theory. The method has high calculation accuracy and fast screening speed, and can save a lot of manpower and material resources required for the preparation of pyridyl transition metal single atom structures and adsorption and gas sensing experiments;

[0028] (2) In the conventional gas adsorption calculation based on density functional theory, the present invention divides the adsorption energy into two parts for discussion, including chemical adsorption and van der Waals force. By calculating the proportion of van der Waals force, the strength of physical adsorption and chemical adsorption can be accurately quantified, which is significantly helpful for analyzing the adsorption characteristics of gas molecules and their physical and chemical interactions with the surface;

[0029] (3) Compared with the existing C4F7N adsorption calculation, the present invention further explores the bonding characteristics of C4F7N and transition metal active sites during gas adsorption, quantitatively evaluates the strength of the chemical bonds between different pyridyl transition metal single atoms and C4F7N, and can more accurately explore the physical and chemical interaction mechanism between C4F7N and active sites. The present invention has obvious advantages and broad application prospects in the research of gas molecule adsorption and active site design, and also provides a theoretical reference for the design of high-performance adsorbents and gas-sensitive materials based on single-atom structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Figure 1 Flowchart of the present invention

[0032] Figure 2 The single atom structure of pyridyl transition metal and the molecular structure of C4F7N, where (a) is the single atom structure of pyridyl transition metal and (b) is the molecular structure of C4F7N;

[0033] Figure 3 The structural diagrams of 10 optimized pyridyl transition metal single atom sites (TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) adsorbed on C4F7N;

[0034] Figure 4 Schematic diagram of the adsorption energy and van der Waals proportion of C4F7N at different pyridyl transition metal single atom sites;

[0035] Figure 5 Schematic diagram of charge transfer comparison of C4F7N at different pyridyl transition metal single atom sites;

[0036] Figure 6 -COHP curves of N atoms in C4F7N and different pyridyl transition metal single atoms, (a) to (j) are different elements of transition metal single atoms;

[0037] Figure 7 Schematic diagram of -ICOHP between N atom and different pyridyl transition metal single atom sites in C4F7N; DETAILED DESCRIPTION

[0038] The present invention takes 10 pyridyl transition metal single atom structures (TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) as examples, and further describes the present invention in detail from the aspects of model establishment and optimization, adsorption energy, van der Waals force ratio, charge transfer, COHP calculation and physicochemical interaction analysis, etc., in combination with the accompanying drawings and examples. It should be noted that the content of the embodiments is only used to illustrate the present invention and is not limited to the present invention.

[0039] The present invention provides a specific embodiment of a method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites, comprising the following steps:

[0040] (1) Step S1: Using atomic modeling software (preferably the Visualization module of Materials Studio) to construct the microstructure of the pyridyl transition metal single atom site and the C4F7N molecular microstructure

[0041] The pyridyl transition metal single atom structure is a non-periodic structure, with a single transition metal atom (TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) at the center, and four nitrogen (N) atoms coordinated around it to form a pyridine ring, forming a pyridyl TM-N4 structure. The pyridyl TN-N4 structure is surrounded by hexagonal graphene-like carbon atoms, surrounded by hydrogen atoms to prevent the formation of dangling bonds. Sufficient carbon atoms are built around the pyridyl TM-N4 structure to prevent the edge structure from interfering with the overall adsorption characteristics of TM-N4. The entire structure includes 1 transition metal atom, 4 nitrogen atoms, 74 carbon atoms and 22 hydrogen atoms. The C4F7N molecular structure is also a non-periodic structure, with the central carbon atom connected to 2 CF3 groups, 1 fluorine atom and 1 C≡N group. The pyridyl transition metal single atom structure and the C4F7N structure are as follows Figure 1 shown.

[0042] (2) Step S2: Using DMol 3 The module calculates the adsorption structure, adsorption energy, van der Waals force ratio and charge transfer of C4F7N molecules on pyridyl transition metal single atom sites

[0043] First, the initial adsorption structure is established: the transition metal is set as the adsorption site of the gas molecule, the adsorption direction is that the C≡N triple bond in the C4F7N molecule is perpendicular to the transition metal atom and the N atom is facing downward, and the distance between the transition metal atom and the N atom is to In DMol 3In the module, the initial adsorption structure is geometrically optimized based on density functional theory. Select Geometric optimization and select the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional in the Generalized Gradient Approximation (GGA). Set the geometric optimization convergence standard, where the energy convergence standard is 1×10 -6 Ha, the maximum atomic force is The maximum displacement distance is According to this convergence criterion, the atomic structures of 10 pyridyl transition metal single atom sites adsorbed on C4F7N were optimized, such as Figure 2 Among them, the adsorption distances of Mn-N4, Fe-N4, Co-N4, Ru-N4, Rh-N4 and Ir-N4 are shorter, all less than Moreover, the C—C≡N bond angles in the C4F7N molecules are all less than 180°, namely 143° (Mn-N4), 147° (Fe-N4), 170° (Co-N4), 142° (Ru-N4), 174° (Rh-N4), and 167° (Ir-N4), indicating that the molecular structure of C4F7N undergoes obvious changes after adsorption on the above six pyridyl TM-N4 sites.

[0044] After obtaining the adsorption structure, the pyridyl transition metal single atom structure and the C4F7N molecule without adsorbed C4F7N molecule are optimized according to the same geometric optimization convergence standard to obtain the energy of the two. The adsorption energy of C4F7N molecule on the pyridyl transition metal single atom site is calculated using the following formula:

[0045]

[0046] Where E TM-N4 / C4F7N is the total energy after optimization of pyridyl transition metal single atom adsorption on C4F7N, E TM-N4 is the total energy of the optimized pyridyl transition metal single atom TM-N4 structure, E C4F7N is the total energy of the optimized C4F7N molecule. E a The calculations were performed with and without "Grimme" checked to obtain the adsorption energies corrected for van der Waals forces and those without van der Waals force correction. The calculation process of the van der Waals force fraction is as follows:

[0047]

[0048] Where R is the proportion of van der Waals force, E a(noVDW) is the adsorption energy without considering the van der Waals correction, E a(VDW) is the adsorption energy when considering the van der Waals correction.

[0049] The calculation results of adsorption energy and van der Waals force ratio are shown in Table 1 and Figure 3 As shown. Among them, the absolute values ​​of the adsorption energy of Fe-N4 and Ru-N4 on C4F7N are both greater than 1.0eV, reaching -1.17eV and -1.66eV respectively, and the proportion of van der Waals force is only 0.36 and 0.25 respectively, which is significantly smaller than other TM-N4 structures, indicating that these two structures not only have large adsorption energy, but also have a high proportion of chemical adsorption, and have obvious chemical adsorption effects on C4F7N. The absolute values ​​of the adsorption energy of Mn-N4 and Co-N4 are between 0.5 and 1eV, and the proportion of van der Waals force is 0.51 and 0.59 respectively, both around 0.5, indicating that both physical adsorption and chemical adsorption contribute. For Ni-N4, Cu-N4, Rh-N4, Pd-N4, Pd-N4 and Ir-N4, the absolute values ​​of the adsorption energy are not greater than 0.5eV, and the proportion of van der Waals force is above 0.8, then physical adsorption dominates.

[0050] The Hirshfeld method was used to calculate the charge transfer between the pyridyl transition metal atom and C4F7N. 3 In the electronic structure calculation of the module, check Population analysis to obtain the Hirshfeld charge of each atom, add up the charge of each atom in the C4F7N molecule, and then calculate the charge transfer between the pyridyl transition metal atom and C4F7N. The calculation results are shown in Table 1 and Figure 4 As shown. Among them, the amount of charge transfer during the adsorption of Mn-N4, Fe-N4, and Ru-N4 is large, and the absolute value is greater than or equal to 0.1e, and C4F7N is negatively charged after adsorption, indicating that it has gained electrons. For the Rh-N4 structure, C4F7N is also negatively charged, but the charge transfer is only -0.06e. During the adsorption of the other six TM-N4 structures, C4F7N loses electrons and becomes an electron donor.

[0051] Table 1

[0052]

[0053] (3) Step S3: According to the adsorption structure in S2, DMol 3 The module calculates the COHP and its integral value between a single pyridyl transition metal atom and a C4F7N molecule

[0054] For the optimized adsorption structure, in DMol 3In the module for electronic structure calculation, check Calculate crystal orbital populations in Density ofstate, set the N atom and the pyridyl-centered transition metal atom in C4F7N as COHP objects, and calculate the COHP value of TM-N. Based on the COHP calculation results, make a -COHP curve of C4F7N at different pyridyl-centered transition metal single atom sites, such as Figure 5 As shown. If there are two curve colors in the figure, it means that the optimized adsorption structure is magnetic. If there is only one color, it means that the spin-up and spin-down curves coincide, and the structure is not magnetic. The right end of the dotted line is the bonding orbital, and the left end is the antibonding orbital. According to the figure, only Mn-N4 and Co-N4 are magnetic after adsorbing C4F7N. And for Ni-N4, Cu-N4, Pd-N4 and Pt-N4, the values ​​of the -COHP curve are all small, indicating that basically no new bonds are formed after the four structures are adsorbed, which is also consistent with the adsorption energy results (only -0.33, -0.37, -0.33 and -0.36eV).

[0055] Integrate the -COHP curve from -∞ to 0:

[0056]

[0057] Where -ICOHP is the integral value and E is the energy value. The -ICOHP results between different pyridyl-centered transition metal atoms and C4F7N are shown in Figure 6 , 7 As shown in Table 2, its value reflects the strength of the chemical bond between the TM and N in the pyridine-centered transition metal single atom structure in C4F7N. The stronger the -ICOHP, the greater the strength of the chemical bond. Among them, the -ICOHP values ​​of Mn-N4 and Fe-N4 reached 7.57 and 8.30, indicating that the strength of the newly generated TM-N chemical bond after adsorption is greater than that of the adsorption of the other TM-N4 structures. The -ICOHP of Ru-N4 and Co-N4 are 5.29 and 4.85, respectively, and the strength of the newly generated chemical bond after adsorption is slightly weaker than that of Mn-N4 and Fe-N4. The -COHP values ​​of Ir-N4 and Rh-N4 are 3.20 and 2.28, respectively, and the strength of the new chemical bond is even weaker. For Ni-N4, Cu-N4, Pd-N4 and Pt-N4, their -ICOHP is small, all less than 1, so after these four TM-N4 adsorb C4F7N, basically no new chemical bonds are generated.

[0058] Table 2

[0059]

[0060] (4) Step S4: Based on the adsorption energy, van der Waals force ratio, charge transfer in S2 and the COHP calculation results in S3, the chemical bond strength between the pyridyl transition metal atom and the C4F7N molecule is analyzed to reveal the interaction mechanism between the two.

[0061] This paper combines the adsorption energy, van der Waals force ratio, charge transfer and COHP calculation results to further explore the interaction mechanism between the pyridine-based transition metal single atom structure and C4F7N.

[0062] At present, the research on gas adsorption is limited to exploring the correlation between adsorption energy and adsorption intensity. The present invention further considers the proportion of van der Waals force, thereby quantitatively analyzing physical adsorption and chemical adsorption. According to the calculation results in Table 1, the adsorption structures of 10 pyridyl TM-N4s have a van der Waals force range of -0.3 to -0.44 eV. Therefore, physical adsorption is basically not affected by the central atom of the TM-N4 structure. The chemical adsorption is closely related to different TM-N4 structures and TM element types. Among them, the total adsorption energy and chemical adsorption energy of pyridyl Ru-N4 for C4F7N are the largest, and desorption is not easy to occur. Therefore, pyridyl Ru-N4 is most suitable as an adsorbent for C4F7N gas at room temperature.

[0063] In addition, the performance of semiconductor gas sensors is related to adsorption and charge transfer. When chemical adsorption and bonding occur between gas molecules and gas-sensitive materials, the charge transfer between the two causes the change of carriers in the gas-sensitive material, and then the resistivity changes, resulting in a response. The adsorption energy and chemical adsorption energy of pyridyl Mn-N4, Fe-N4 and Ru-N4 are the largest, and the -ICOHP values ​​of the three are all over 5. Compared with other pyridyl TM-N4 structures, there is obvious new TM-N bond generation during the C4F7N adsorption process, and the absolute value of charge transfer is not less than 0.10e. Therefore, the three pyridyl TM-N4 are suitable as gas-sensitive materials for detecting C4F7N. If the pyridyl TM-N4 is an n-type semiconductor, it will lose electrons when detecting C4F7N, resulting in an increase in resistance, and vice versa. Through the above method, the adsorption and sensing properties of different pyridine-based TM-N4 and other single-atom structures on C4F7N and the interaction mechanism between the two can be analyzed, providing a reference for the design and development of high-performance C4F7N adsorption and sensing materials.

[0064] The above further illustrates the implementation method of the present invention through the accompanying drawings and a typical embodiment. It should be noted that the above embodiment can provide technical reference for relevant technical personnel in this profession. If other technical solutions are changed, modified or adjusted on the basis of the present invention, they should still fall within the scope of protection required by the present invention.

Claims

1. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites, characterized in that: The following steps are involved: S1: Use atomic modeling software to construct the microstructure of the pyridyl transition metal single atom site and the C4F7N molecular microstructure; S2: Using DMol 3 The module calculates the adsorption structure, adsorption energy, van der Waals force ratio and charge transfer of C4F7N molecules on pyridyl transition metal single atom sites; S3: According to the adsorption structure in S2, DMol 3 The module calculates the Crystal Orbital Hamilton Populations (COHP) and its integral value between pyridyl transition metal single atoms and C4F7N molecules; S4: Based on the adsorption energy, van der Waals force ratio, charge transfer in S2 and COHP calculation results in S3, the chemical bond strength between the pyridine transition metal single atom and the C4F7N molecule is analyzed to reveal the interaction mechanism between the two.

2. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to claim 1, characterized in that: The pyridyl transition metal single atom site structure constructed in step S1 is: a single transition metal atom in the center and four nitrogen (N) atoms coordinated around it form a pyridine ring, constituting a pyridyl TM-N4 structure.

3. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to claim 1, characterized in that: The specific calculation process of the adsorption structure in step S2 is: In DMol 3 In the module, check Geometric optimization to optimize the microstructure of C4F7N molecules at the pyridyl transition metal single atom site, select the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional in the Generalized Gradient Approximation (GGA), and set the geometric optimization convergence criterion, where the energy convergence criterion is 1×10 -6 Ha, the maximum atomic force is The maximum displacement distance is 4. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to claim 1, characterized in that: In step S2, the adsorption energy calculation process is as follows: Where E a is the adsorption energy, E TM-N4 / C4F7N is the total energy after optimization of pyridyl transition metal single atom adsorption on C4F7N, E TM-N4 is the total energy of the optimized pyridyl transition metal single atom TM-N4 structure, E C4F7N is the total energy of the optimized C4F7N molecule. E a Calculate with "Grimme" checked and unchecked to obtain the adsorption energy with and without Van der Waals' force (VDW) correction; The calculation process of the van der Waals force ratio is as follows: Where R is the proportion of van der Waals force, E a(noVDW) is the adsorption energy without considering the van der Waals correction, E a(VDW) In order to consider the adsorption energy with van der Waals correction, the charge transfer was calculated using the Hirshfeld method.

5. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to claim 1, characterized in that: In step S3, the COHP and its integral value between the pyridyl transition metal single atom and the C4F7N molecule are calculated, and the specific process is as follows: For the optimized adsorption structure, in DMol 3 In the module for electronic structure calculation, check Calculate crystal orbital populations in Density of state, and set the N atom and the pyridyl-centered transition metal atom in C4F7N as COHP calculation objects; According to the calculation results, after making the -COHP curve of C4F7N at different pyridyl transition metal single atom sites, the curve is integrated from -∞ to 0: Where -ICOHP is the integral value and E is the energy value.

6. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to claim 1, characterized in that: The analysis process of step S4 includes: evaluating the adsorption strength of C4F7N at different pyridyl transition metal single atom sites by comparing the adsorption energy, and evaluating the chemical adsorption effect by combining the proportion of van der Waals force; evaluating the electron gain and loss characteristics after the pyridyl transition metal single atom site adsorbs C4F7N by comparing the charge transfer size; comparing the -ICOHP values ​​between different pyridyl transition metal nitrogen atom sites and C4F7N, and further evaluating the chemical bond strength between the two.

7. A method for analyzing the adsorption and bonding strength of C4F7N molecules at pyridyl transition metal single atom sites according to any one of claims 1 to 6, characterized in that: The atomic modeling software adopts the Visualization module of Materials Studio.

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