A method for predicting catalytic performance of different curvature tubular fe-n-co2 co2 rr

Abstract

The present application belongs to the technical field of electrochemical catalysis, and provides a method for predicting the catalytic performance of tubular iron-nitrogen-carbon for CO2RR with different curvatures, which is mainly used for predicting the influence of different curvatures on the catalytic performance of tubular iron-nitrogen-carbon for CO2RR, and the main scheme comprises the following steps: a half-pipe iron-nitrogen-carbon structure model is established to replace the whole-pipe structure model to preliminarily screen the curvatures, and the feasibility and advantages of this method are explored; based on the screened iron-nitrogen-carbons with different curvatures, the influence of the curvatures on the catalytic performance of the iron-nitrogen-carbon for CO2RR is analyzed; and the influence of the curvatures on the electronic properties of the iron-nitrogen-carbon system is analyzed based on Bader charge. Under the premise of ensuring the accuracy of the method, the present application saves the calculation resources, predicts the influence of different curvatures on the catalytic performance of the tubular iron-nitrogen-carbon for CO2RR, explores the influence law of the curvatures on the catalytic activity and selectivity of the iron-nitrogen-carbon catalyst, and can be used for guiding the subsequent experimental research work.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, specifically, it relates to a method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures. Background Technology

[0002] Electrochemical catalytic CO2 reduction (CO2RR) technology can utilize renewable energy sources (solar, wind, hydro, etc.) to achieve its effects. It offers advantages such as no secondary pollution, mild reaction conditions, simple reaction equipment, and controllable products. This technology, with the aid of a catalyst, can reduce excess atmospheric CO2 through multi-electron reduction, converting it into high-energy-density, high-economic-value small molecules (such as carbon monoxide (CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4), ethanol (C2H5OH), ethylene (C2H4), and 16 other carbon-based energy products). This reduces carbon emissions while alleviating human dependence on fossil fuels.

[0003] Metal-nitrogen-doped carbon-based (MNC) electrochemical catalysts, developed based on the excellent conductivity and stability of graphene, possess diverse local synergistic environments and catalytic active sites due to their abundant metal dopants and coordinating atoms. MNC catalysts primarily catalyze CO2RR with the C1 product CO, exhibiting poor selectivity for non-CO C1 products. Recent studies have shown that curved structures can weaken the interaction between metal atoms and surrounding atoms in MNC catalysts, altering the electronic structure of metal atoms and increasing the adsorption strength of reaction intermediates, thereby enhancing the catalytic activity of MNC catalysts. Curvature is a descriptor of the degree of surface bending; the greater the curvature of a curved MNC catalyst, the greater its degree of bending, and the greater its influence on the MN groups on the curved surface. Therefore, the performance of curved MNC catalysts can be regulated by changing the curvature. Tubular MNC catalysts are obtained by doping carbon nanotubes with MN groups. They possess a naturally curved surface structure and excellent stability, thus attracting widespread attention in the research of curved MNC catalysts. Tubular MNC catalysts can achieve curvature adjustment simply by changing their diameter; the larger the diameter, the smaller the lateral curvature. Therefore, curvature adjustment of this structure is very easy to achieve in both experimental and computational studies, and the adjustment effect is significant. However, tubular MNC catalyst structures are relatively large, and the number of atoms in the periodically repeating lattice is very large when conducting computational simulations. In addition, the initial curvature screening often requires establishing structures with many different curvatures, thus requiring a large amount of computational time and resources.

[0004] To address the aforementioned problems, this invention proposes a method for predicting the catalytic performance of tubular iron-nitrogen-carbon (FeNiC) CO2RR catalysts with different curvatures. A semi-tubular FeNiC structure is established to replace the whole tubular structure. Density functional theory simulations are used to initially screen tubular FeNiC structures with different curvatures, effectively saving computation time and resources. Electrocatalytic CO2RR processes are simulated on the screened structures with different curvatures, predicting the influence of curvature on the electrocatalytic CO2RR performance of tubular FeNiC catalysts and exploring potential tubular FeNiC catalysts. Summary of the Invention

[0005] The purpose of this invention is to provide a method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures. Under the premise of ensuring the feasibility of the method, it predicts the influence of different curvatures on the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts, explores the influence of curvature on the catalytic activity and selectivity of iron-nitrogen-carbon catalysts, provides guidance for subsequent experimental research, and saves computation time and resources.

[0006] To achieve the above objectives, the present invention provides a method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures, comprising the following steps:

[0007] Step 1: Establish a semi-tube iron-nitrogen-carbon structural model to replace the whole-tube structural model for preliminary screening of curvature, resulting in a series of iron-nitrogen-carbon structures with different curvatures;

[0008] Step 2: Based on the selected iron-nitrogen-carbon structures with different curvatures, analyze the effect of curvature on the CO2RR catalytic performance of iron-nitrogen-carbon structures. On the one hand, calculate the free energy ΔG corresponding to the reduction of CO2 to CO by the selected iron-nitrogen-carbon structures with different curvatures. On the other hand, draw the CO2RR path free energy diagram of iron-nitrogen-carbon structures with different curvatures at 0 potential.

[0009] Step 3: Based on the influence of curvature on the electronic properties of the iron-nitrogen-carbon system by Bader charge analysis, explain why the introduction of curvature affects the performance of the catalyst and obtain the results of Bader charge analysis;

[0010] Step 4: Final results from Bade charge analysis and free energy. Figure 1 By changing the curvature of tubular iron-nitrogen-carbon, the catalytic performance of CO2RR of tubular iron-nitrogen-carbon with different curvatures can be predicted.

[0011] Furthermore, step 1 includes the following steps:

[0012] Step 1.1: Establish a series of single-walled carbon nanotube models with radii ranging from small to large;

[0013] Step 1.2: Remove half of the carbon atoms along the direction perpendicular to the cross-section of the nanotube, passivate the edges of the remaining curved structure with hydrogen atoms, and fix the carbon and hydrogen atoms on both sides of the curved surface.

[0014] Step 1.3: Doping a tetragen-iron group onto the curved surface, and after selective structure optimization, a series of curved iron-nitrogen-carbon structures are obtained;

[0015] Step 1.4: Randomly select three structures from these structures, using iron atoms as adsorption sites for adsorption groups or molecules, and statistically analyze the difference in adsorption energy ΔE between these structures and the whole tubular structure, as well as the computation time required under the same calculation conditions. Specifically, this includes:

[0016] ΔE=E M* -E * -E M

[0017] Where ΔE represents the adsorption energy of M on the structure, E M* Let E be the system energy after M adsorption. * E represents the energy of the adsorbed structure. M It represents the energy of a group or molecule.

[0018] By calculating the adsorption energy of a single carbon atom and carbon dioxide molecule on semi-tubular structures with different curvatures, the curvature is initially screened.

[0019] Furthermore, step 2 includes the following steps:

[0020] Step 2.1: Calculate the free energy ΔG corresponding to the reduction of CO2 to CO for the selected iron-nitrogen-carbon structures with different curvatures.

[0021] In step 2.1, the free energy ΔG corresponding to the reduction of CO2 to CO by the selected iron-nitrogen-carbon structures with different curvatures is calculated, specifically including:

[0022] ΔG=ΔE-TΔS+ΔE ZPE :

[0023] ΔS=S( pro )-S (rea) ;

[0024] ΔE ZPE =ZPE (pro) -ZPE (rea) ;

[0025] Where ΔE is the adsorption energy of the group or molecule on the structure; T is the temperature; ΔS is the entropy change before and after the reaction; and S is the entropy change before and after the reaction. (pro) S is the entropy of the reaction products. (rea) The entropy of the reactants; ΔE ZPE ZPE is the difference in zero-point energy before and after the reaction. (pro) ZPE is the zero-point energy of the reaction products. (rea) This is the zero-point energy of the reactants.

[0026] Furthermore, step 2 includes the following steps:

[0027] Step 2.2: Draw the CO2RR path free energy diagram of iron-nitrogen-carbon structures with different curvatures at 0 potential.

[0028] In step 2.2, the CO2RR path free energy diagrams of iron-nitrogen-carbon structures with different curvatures at 0 potential are plotted, specifically including:

[0029] Plot the CO production reaction path free energy diagram at 0 potential with *+CO2, COOH*, CO*, and *+CO as the x-axis and CO2RR path free energy as the y-axis.

[0030] Furthermore, step 3 includes the following steps:

[0031] Step 3.1: Calculate the Bader charge of iron atoms in iron-nitrogen-carbon with different curvatures, and analyze the charge transfer of iron atoms under different curvature configurations.

[0032] Advantages and beneficial effects of the method of the present invention:

[0033] First, compared with the existing technology, the present invention first establishes a semi-tube iron-nitrogen-carbon structure to replace the whole tube structure for preliminary screening, while ensuring the accuracy of the calculation results, which greatly reduces the calculation time and computing resources.

[0034] Second, this invention uses density functional theory to calculate and simulate the process of structural electrocatalysis of CO2RR, revealing the influence of curvature on the performance of tubular iron-nitrogen-carbon electrocatalysis of CO2RR, exploring potential tubular iron-nitrogen-carbon catalysts, and providing guidance for subsequent experimental synthesis. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Figure 1 This is a schematic diagram of the model of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the modeling method and the feasibility of the verification method.

[0038] Figure 3 Free energy diagrams for CO2RR to CO products catalyzed by different curvature structures;

[0039] Figure 4 Bader charge maps of Fe atoms at active sites in structures with different curvatures; Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0041] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures, provided by an embodiment of the present invention. Specifically, the method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures may include the following steps:

[0042] A semi-tube iron-nitrogen-carbon structural model was established to replace the whole tube structural model for preliminary screening of curvature, and the feasibility and advantages of this approach were explored.

[0043] In the embodiments of this invention, please refer to Figure 2 , Figure 2 This is a schematic diagram illustrating the feasibility and advantages of using a semi-tubular iron-nitrogen-carbon structure model to preliminarily screen curvature instead of a full-tubular structure model. Specifically, the method involves first establishing a series of single-walled carbon nanotube models with radii ranging from small to large; then removing half of the carbon atoms along the direction perpendicular to the nanotube cross-section, passivating the edges of the remaining curved structure with hydrogen atoms, and fixing the carbon and hydrogen atoms on both sides of the curved surface; doping the curved surface with an iron-nitrogen tetra group, and then performing optimization calculations on the structure; randomly selecting three of these structures, using iron atoms as adsorption sites for adsorption groups or molecules, and comparing the difference in adsorption energy ΔE with the full-tubular structure, as well as the computation time required under the same calculation conditions. A total of 19 semi-tubular structures were established, with diameters ranging from... arrive Three semi-tubular structures were randomly selected. Compared with the corresponding tubular structures, the maximum difference in adsorption energy for each group or molecule was 0.03 eV, demonstrating the feasibility of this approach. Using the same number of computational cores, the semi-tubular structure can save up to 56% of the computation time compared to the tubular structure, indicating that this approach effectively improves computational screening efficiency and saves computational resources.

[0044] The 19 structures were numbered 1-19, and their adsorption energies for a single carbon atom and a carbon dioxide molecule were calculated. The results are shown in [reference needed]. Figure 2The curvature of the planar iron-nitrogen-carbon structure can be considered zero. The dashed lines represent the adsorption energies of the planar iron-nitrogen-carbon structure for a single carbon atom and carbon dioxide molecule. It can be seen that the adsorption energies of all curvature structures for a single carbon atom and carbon dioxide molecule are lower than those of the planar iron-nitrogen-carbon structure. In particular, structures 1-7 show a more significant moderating effect on the adsorption energies of a single carbon atom and carbon dioxide molecule. However, the adsorption energies of structures 4 and 5, and 6 and 7 for both are relatively close. To maximize the difference in curvature between the screened structures, the tube structures corresponding to structures 1, 2, 3, 5, and 7 were selected for further research. Their diameters are as follows:

[0045] Based on the selected iron-nitrogen-carbon compounds with different curvatures, the effect of curvature on the CO2RR catalytic performance of iron-nitrogen-carbon was analyzed.

[0046] In this embodiment of the invention, based on the selected iron-nitrogen-carbon structures with different curvatures, the effect of curvature on the CO2RR catalytic performance of the iron-nitrogen-carbon structures is analyzed; specifically, the free energy ΔG corresponding to the reduction of CO2 to CO by the selected iron-nitrogen-carbon structures with different curvatures is:

[0047] ΔG=ΔE-TΔS+ΔE ZPE ;

[0048] ΔS=S (pro) -S (rea) ;

[0049] ΔE ZPE =ZPE (pro) -ZPE (rea) ;

[0050] Where ΔE is the adsorption energy of the group or molecule on the structure; T is the temperature (taken as 298.15 K here); ΔS is the entropy change before and after the reaction; and S... (pro) S is the entropy of the reaction products. (rea) The entropy of the reactants; ΔE ZPE ZPE is the difference in zero-point energy before and after the reaction. (pro) ZPE is the zero-point energy of the reaction products. (rea) This is the zero-point energy of the reactants.

[0051] Plot the CO2RR path free energy diagrams for iron-nitrogen-carbon structures with different curvatures at 0 potential, specifically including:

[0052] A free energy diagram of the CO production reaction path at 0 potential was plotted with *+CO2, COOH*, CO*, and α+CO as the x-axis and the CO2RR path free energy as the y-axis. The results are as follows: Figure 3As shown in the diagram, the free energy plots reveal that curvature does indeed regulate the CO2 RR catalysis of tubular iron-nitrogen-carbon catalysts. Structure 1 catalyzes the CO2 to CO transition from *CO to CO, with a ΔG of 0.72 eV, higher than the 0.68 eV of planar iron-nitrogen-carbon catalysts. However, the free energy change for CO2 to *COOH catalyzes by structure 1 is 0.09 eV, 0.59 eV lower than the 0.68 eV of planar iron-nitrogen-carbon catalysts. This indicates that structure 1 is more inclined to catalyze CO2 as a non-CO product, proving that the introduction of curvature alters the selectivity of the iron-nitrogen-carbon catalyst. Structures 5 and 7 catalyze the CO2 to CO transition from CO2 to *COOH, with ΔG values ​​of 0.60 and 0.66 eV respectively, both lower than the 0.68 eV of planar iron-nitrogen-carbon catalysts. Structure 5 shows a free energy reduction of 0.08 eV, demonstrating that the introduction of curvature enhances the activity of the iron-nitrogen-carbon catalyst. In summary, the main product of planar iron-nitrogen-carbon electrocatalytic CO2RR is CO. Introducing the curvature corresponding to structure 1 into the planar iron-nitrogen-carbon catalyst can change its product selectivity, and introducing the curvature corresponding to structure 5 into the planar iron-nitrogen-carbon catalyst can enhance its activity in producing CO.

[0053] The effect of curvature on the electronic properties of the iron-nitrogen-carbon system was analyzed based on Bader charge analysis.

[0054] In this embodiment of the invention, Bader charge maps of iron atoms at catalytically active sites in tubular iron-nitrogen-carbon structures with different curvatures were established. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a Bader charge diagram of iron atoms at active sites in different curvature structures of the present invention. The dashed lines in the diagram represent the Bader charge of iron atoms in planar iron-nitrogen-carbon catalysts. It can be seen that the introduction of curvature alters the Bader charge of iron atoms. The general trend of Bader charge variation in tubular iron-nitrogen-carbon catalysts is that the greater the curvature, the greater the charge value; as the curvature decreases, the charge value approaches that of planar catalysts. Since iron atoms have 8 valence electrons, a larger Bader charge value indicates more charge on the iron atom and less charge transferred to surrounding atoms. This means that more charge can be provided during the catalytic CO2RR process, demonstrating that a larger curvature in the tubular iron-nitrogen-carbon catalyst has a greater impact on the electronic structure of iron atoms, and a weaker interaction between iron atoms and surrounding atoms, thereby increasing the adsorption strength of reaction intermediates and enhancing the catalytic activity of the catalyst.

[0055] This invention provides a method for predicting the catalytic performance of tubular iron-nitrogen-carbon (FeNiC) CO2RR catalysts with different curvatures. It establishes a semi-tubular FeNiC structural model instead of a full-tubular model to initially screen for curvature, exploring the feasibility and advantages of this approach. Based on the screened FeNiC catalysts with different curvatures, the influence of curvature on the FeNiC CO2RR catalytic performance is analyzed. Furthermore, the influence of curvature on the electronic properties of the FeNiC system is analyzed based on Bader charge analysis. While ensuring the accuracy of the method, this invention saves computational resources, predicts the influence of different curvatures on the catalytic performance of tubular FeNiC CO2RR catalysts, and explores the influence of curvature on the catalytic activity and selectivity of FeNiC catalysts. This method can guide subsequent experimental research.

[0056] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures, characterized in that, include: A semi-tube iron-nitrogen-carbon structural model was established to replace the whole-tube structural model for preliminary screening of curvature, resulting in a series of iron-nitrogen-carbon structures with different curvatures. Based on the selected iron-nitrogen-carbon structures with different curvatures, the influence of curvature on the CO2RR catalytic performance of iron-nitrogen-carbon structures was analyzed. On the one hand, the free energy ΔG corresponding to the reduction of CO2 to CO by the selected iron-nitrogen-carbon structures with different curvatures was calculated. On the other hand, the CO2RR path free energy diagram of iron-nitrogen-carbon structures with different curvatures at 0 potential was plotted. Based on the influence of curvature on the electronic properties of the iron-nitrogen-carbon system by Bader charge analysis, the reason why the introduction of curvature affects the performance of the catalyst is explained, and the results of Bader charge analysis are obtained. Ultimately, by combining the results of Bade charge analysis with the free energy diagram, the CO2RR catalytic performance of tubular iron-nitrogen-carbon structures with different curvatures was predicted by changing the curvature of the tubular iron-nitrogen-carbon structure. The specific steps for establishing a semi-tube iron-nitrogen-carbon structural model to replace the whole-tube structural model for preliminary curvature screening include: A series of single-walled carbon nanotube models with curvature ranging from large to small were established. Half of the carbon atoms were removed along the direction perpendicular to the cross-section of the nanotube, and the edges of the remaining curved structure were passivated with hydrogen atoms to fix the carbon and hydrogen atoms on both sides of the curved surface. A tetragen-iron group was doped onto the curved surface, and selective structure optimization was performed by setting Selective dynamics in the structure file POSCAR to obtain a series of carbon-iron-nitrogen structures with different curvatures. Three iron-nitrogen-carbon structures with different curvatures were randomly selected. Adsorption groups or molecules were formed using iron atoms as adsorption sites. The differences in adsorption energy compared to the whole tubular structure and the required computation time under the same computational conditions were compared. Specifically, this included: ΔE=E M* -E * -E M Where ΔE represents the adsorption energy of M on the structure, E M* Let E be the system energy after M adsorption. * E represents the energy of the adsorbed structure. M represents the energy of a group or molecule, where M is the group or molecule; By calculating the adsorption energy of a single carbon atom and carbon dioxide molecule on semi-tubular structures with different curvatures, the curvature is initially screened.

2. The method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures as described in claim 1, characterized in that, Based on the selected iron-nitrogen-carbon catalysts with different curvatures, the effect of curvature on the CO2RR catalytic performance of the iron-nitrogen-carbon catalyst was analyzed. The specific steps included: The free energy ΔG corresponding to the reduction of CO2 to CO by the selected iron-nitrogen-carbon structures with different curvatures was calculated.

3. The method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures as described in claim 2, characterized in that, The free energy ΔG for reducing CO2 to CO in iron-nitrogen-carbon structures with different curvatures includes: ΔG=ΔE-TΔS+ΔE ZPE ; ΔS=S (pro) -S (rea) ; ΔE ZPE ZPE (pro) -ZPE (rea) ; Where ΔE is the adsorption energy of the group or molecule on the structure; T is the temperature; ΔS is the entropy change before and after the reaction; and S is the entropy change before and after the reaction. (pro) S is the entropy of the reaction products. (rea) The entropy of the reactants; ΔE ZPE ZPE is the difference in zero-point energy before and after the reaction. (pro) ZPE is the zero-point energy of the reaction products. (rea) This is the zero-point energy of the reactants.

4. The method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures as described in claim 1, characterized in that, Based on the selected iron-nitrogen-carbon catalysts with different curvatures, the effect of curvature on the CO2RR catalytic performance of the iron-nitrogen-carbon catalyst was analyzed. Specific steps included: Plot the CO2RR path free energy diagrams for iron-nitrogen-carbon structures with different curvatures at 0 potential.

5. The method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures as described in claim 4, characterized in that, Plot the CO2RR path free energy diagrams for iron-nitrogen-carbon structures with different curvatures at 0 potential, specifically including: Plot the path free energy diagram of carbon monoxide production at 0 potential, with *+CO2, COOH*, CO*, and *+CO as the x-axis and the CO2RR path free energy as the y-axis.

6. The method for predicting the catalytic performance of tubular iron-nitrogen-carbon CO2RR catalysts with different curvatures as described in claim 1, characterized in that, Based on Bader charge analysis and electronic density of states analysis, the effects of different curvatures on the electronic properties of the iron-nitrogen-carbon system are analyzed. The specific steps include: The Bader charge of iron atoms in iron-nitrogen-carbon catalysis with different curvatures was calculated, and the charge transfer of iron atoms under different curvature configurations was analyzed to obtain the intrinsic factors that regulate the performance of iron-nitrogen-carbon catalysis CO2RR.

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