A rapid screening method for corrosion-resistant crystal planes of copper-group metals

Abstract

The present invention provides a rapid screening method for corrosion-resistant crystal planes of coinage metals, including: simulating the dissolution process of metals at the electrochemical interface using a layered flat periodic model and outputting an electron density distribution file; preprocessing the output file to obtain a plane-average electron density distribution curve along the Z-axis; dividing the intra-layer and inter-layer regions of the atomic layer of the structure; analyzing the change of electron density in the inter-layer and intra-layer regions, and judging the corrosion-resistant dissolution performance of different crystal planes of coinage metals through the proportion of the number of electrons in the inter-layer. The present invention innovatively divides the intra-layer and inter-layer regions of the atomic layer of the first-principles calculation model, can more efficiently perform quantitative calculation of the electron density of the coinage metal structure, and finally obtain a simple and clear distribution map of the proportion of the number of electrons, effectively presenting the difference in electron density distribution caused by structural changes, and can more quickly judge the more corrosion-resistant crystal plane structure compared with performing energy curve calculation.

Description

Technical Field

[0001] The present invention relates to a method for rapidly judging the corrosion resistance related to the crystal plane of copper group metals, which is applicable to the analysis of the simulation calculation results of the electrochemical processes of copper group metals in vacuum or solution, and screens more corrosion-resistant crystal plane structures by analyzing the change of electron density. Background Art

[0002] The first-principles calculation method based on density functional theory has been widely used in the research on the microstructure and properties of crystal materials. In recent years, the development of high-throughput calculations has also given rise to many related simulation calculation software. The first-principles calculation has important scientific significance in material design and principle analysis. Taking the research on electrochemical corrosion behavior as an example, at the experimental level, it is often difficult to conduct microscopic-scale research due to reasons such as cost and accuracy, while the first-principles calculation has become an increasingly widely used effective research method. In the process of calculating and simulating the electrochemical interface, a layered slab model is often used for the electrode part and the crystal periodic boundary conditions are applied. The solution layer is added between the metal surface and the vacuum isolation layer above to perform a series of simulation calculations. By establishing a relevant model around the electrochemical interface of metal materials, through the fine calculation at the atomic and electronic scales theoretically and combining the relationship between the material components and structures, the mechanism related to the corrosion phenomenon of the material can be explored, and then assist and guide experiments to improve the corrosion resistance of the material. Among them, different crystal orientations have an important influence on the corrosion behavior of metals. Obtaining more corrosion-resistant crystal plane structures by experimental or computational means is of great significance for the research and design of metal electrode materials.

[0003] In the microscopic-scale simulation process of the first-principles, the distribution of electron density in the crystal structure has a strong influence on the adsorption and binding properties of the material. By analyzing the difference in electron density distribution, the reasons for various electrochemical behaviors can be revealed. Based on this, it is an urgent need in the art to use a simple and intuitive electron density analysis method to judge the more corrosion-resistant crystal plane structure of a metal copper electrode. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a rapid screening method for the corrosion-resistant crystal planes of copper group metals, and solves the technical problems proposed in the above background art.

[0005] To achieve the above object, one aspect of the present invention provides a rapid screening method for the corrosion-resistant crystal planes of copper group metals, including the following steps:

[0006] S1. Based on the JDFTx computational software, a layered flat plate model is used to simulate and establish an electrochemical interface, and an initial calculation is performed on the copper group metal model to obtain the output results of the structural calculation; in the output file, an electron density distribution file at each position in the spatial coordinate axes (x, y, z) after the corresponding k-point grid division is obtained;

[0007] S2. Based on the initial electron density distribution file, a distribution curve of the average electron density along the Z-axis is established using a calculation script;

[0008] S3. Based on the distribution curve of the electron density along the Z-axis obtained in S2, the intra-atomic layer and inter-layer regions are divided in the model atomic layer structure;

[0009] S4. Analyze the changes in the electron density in the inter-layer and intra-layer regions, and judge the corrosion-resistant dissolution performance of the copper group metal electrode structure by the proportion of the number of electrons in the inter-layer.

[0010] Preferably, the distribution curve of the average electron density along the Z-axis is established using a calculation script:

[0011] Preprocess the initial electron density distribution file of the spatial coordinate axes (x, y, z), and the electron density distribution at the corresponding a×b×c spatial grid points is known; perform summation and averaging on the electron density on the plane perpendicular to the Z-axis, that is, convert the series of a×b×c data point sets in space into an m×c two-dimensional matrix; take the position of the middle layer atom of the electrode structure as the 0 point, and connect the surface-averaged electron density sites distributed along the Z-axis to obtain the distribution curve of the electron density along the Z-axis.

[0012] Preferably, the division of the intra-atomic layer and inter-layer regions in the model atomic layer structure includes:

[0013] The coordinates of each atomic layer in the Z-axis direction and the volume parameters of the model in the calculation model are known, and the distance d between adjacent atomic layers in the structure is calculated accordingly; the atomic layer spacing is divided into 4 equal parts on average, and the two side parts are respectively attributed to the intra-atomic layer regions of the corresponding adjacent atomic layers, and the middle two equal parts are combined and called the inter-layer region of the two atomic layers.

[0014] Preferably, the analysis of the changes in the electron density in the inter-layer and intra-layer regions includes:

[0015] Sum the electron densities of two adjacent sites on the left and right sides of the division critical line respectively, and reallocate the electron densities of these two sites according to the ratio of their respective distances from the critical line; according to the distribution of the electron density along the Z-axis and the volume parameters of the structure, integrate the electron density in each divided region to obtain the total number of electrons in the corresponding region; calculate the proportion of the number of electrons in each region to the total number of electrons in the entire structure, and present it by drawing.

[0016] Preferably, the preprocessing of the initial electron density distribution file for the spatial coordinate axes (x, y, z) includes:

[0017] Extract the coordinates and perform operations on the point set in the model in the form of a python program file.

[0018] Preferably, the rapid screening method is also applicable to the simulation of the electrochemical interface of the Bulk structure model, and the corrosion resistance of different crystal planes of the coinage metals is studied for comparative analysis and calculation.

[0019] Compared with the prior art, the present invention provides a rapid screening method for the corrosion-resistant crystal planes of coinage metals, having the following beneficial effects:

[0020] 1. The rapid screening method for the corrosion-resistant crystal planes of coinage metals provided by the present invention innovatively divides the intra-layer and inter-layer regions of the atomic layer of the first-principles calculation model, can more efficiently quantify the electron density of the coinage metal structure, and finally obtains a simple and clear electron number ratio distribution map, effectively presenting the difference in electron density distribution caused by structural changes, and then quickly judging the more corrosion-resistant crystal plane structure.

[0021] 2. The rapid screening method for the corrosion-resistant crystal planes of coinage metals provided by the present invention is simple and efficient, does not require complex calculation means, can present an intuitive and clear electron number ratio distribution map, can fully realize an automated processing flow through a script program, can effectively improve the efficiency of processing calculation simulation results and promote the simulation research process, and accelerate the judgment of the corrosion resistance and characteristics of coinage metals.

[0022] 3. The rapid screening method for the corrosion-resistant crystal planes of coinage metals of the present invention is applicable to the processing and analysis of the first-principles calculation results of various coinage metals using a flat periodic model, and can output calculation results for different differential structures such as the Bulk vacuum structure model, so as to perform effective intuitive comparison. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flowchart of the rapid screening method for the corrosion-resistant crystal planes of coinage metals provided by the present invention;

[0024] Figure 2 is a curve showing the change in the adsorption energy of solute Cu atoms on the surface of each crystal plane electrode structure of the metal Cu material as an example in the preferred embodiment of the present invention under different applied net charges: (a) Cu(110), (b) Cu(100), (c) Cu(111) planes;

[0025] Figure 3In a preferred embodiment of the present invention, taking a metal Cu material as an example, the electronic density output file of the initial simulation calculation is preprocessed, and a schematic diagram of the distribution of the cross-sectional average electronic density along the Z-axis of the Slab structure and the Bulk structure of the Cu electrode system on each crystal plane is obtained by plotting;

[0026] Figure 4 In a preferred embodiment of the present invention, further, a distribution diagram of the proportion of the number of electrons in each divided region of the atoms of the crystal plane structure of the Cu electrode finally obtained by dividing the intra-layer and inter-layer regions of the atoms;

[0027] Figure 5 In a preferred embodiment of the present invention, further, a distribution diagram of the proportion of the number of electrons in the intra-layer and inter-layer regions of the atomic layer of each crystal plane structure is obtained by increasing the number of atomic layers of the single-crystal Cu electrode simulation structure;

[0028] Figure 6 In a preferred embodiment of the present invention, first-principles related calculations are carried out again with a metal Ag material, and finally a distribution diagram of the proportion of the number of electrons in the corresponding regions is obtained; Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Figure 1 The flowchart of the rapid screening method for the corrosion-resistant crystal planes of copper group metals provided by the present invention is shown. As Figure 1 shown, the present invention provides a rapid screening method for the corrosion-resistant crystal planes of copper group metals, including:

[0031] S1. Based on the DFT calculation software, a layered flat plate model is used to simulate and establish an electrochemical interface, and an initial calculation is carried out on the copper group metal model to obtain the output result of the structure calculation; in the output file, an electronic density distribution file at each position in the spatial coordinate axes (x, y, z) after the corresponding k-point grid division is obtained;

[0032] S2. Based on the initial electronic density distribution file, a distribution curve of the average electronic density along the Z-axis is established by using a calculation script;

[0033] S3. Based on the distribution curve of the electronic density along the Z-axis obtained in S2, the intra-layer and inter-layer regions of the atomic layer structure of the model are divided;

[0034] S4. Analyze the changes in electron density in the interlayer and intralayer regions, and judge the corrosion-resistant dissolution performance of the coinage metal electrode structure by the proportion of the number of interlayer electrons.

[0035] The above solution will be further described below in conjunction with specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0036] Example 1: Taking metal Cu as an example, during the study of the dissolution / adsorption process of Cu atoms on the surfaces of Cu(110), (100), and (111) electrode structures, in order to reveal the more corrosion-resistant Cu electrode crystal plane structure at different electrode potentials, a series of calculations on energy changes are often required.

[0037] Figure 2 In the preferred embodiment of the present invention, taking metal Cu material as an example, the adsorption energy change curves of solute Cu atoms on the surfaces of each crystal plane electrode structure under different applied net charges: (a) Cu(110), (b) Cu(100), (c) Cu(111) plane. As Figure 2 shown, by changing the distance between the solute Cu atom and the electrode surface for a series of calculations, the energy curves of Cu(110), (100), and (111) crystal planes as single crystal electrode structures changing with the distance between the Cu atom and the surface under different applied net charges can be obtained. Figure 2 The horizontal axis in the figure is the distance between the solute atom and the outermost atomic layer The vertical axis is the adsorption energy E of the current system ad (eV). Each curve corresponds to a different applied net charge, which is represented by different grayscales accordingly. The solid line represents the process in which the adsorbed Cu atoms can spontaneously dissolve to the electrolyte interface. The gray marked area is the dissolution process of the solute Cu atoms. It can be seen from the adsorption energy curve that the Cu atoms adsorbed on the Cu(110) plane need to apply a larger net charge to dissolve, which further indicates that the Cu(110) plane has better corrosion resistance than the (100) and (111) crystal plane structures. However, this analysis process requires a large number of calculations for a series of numerical points.

[0038] In this embodiment, the rapid screening method for the corrosion-resistant crystal planes of coinage metals includes the following steps:

[0039] S1. Establish an electrochemical interface calculation model and perform first-principles related calculations:

[0040] Based on the JDFTx calculation software, a single-crystal Cu electrode / electrolyte model was established, and the Slab periodic model was used for the calculation. By setting the thickness of the vacuum layer and its related parameters, DFT calculations were performed on the electrode part, and the electrolyte solution environment was added for corresponding simulation calculations. Through a series of calculations, the Slab and Bulk structures of single-crystal electrodes with different orientations of Cu(110), (100), and (111) can be obtained. Among them, the Slab structure is the Slab plate structure of the Cu electrode model relaxed in the solution environment. Twenty atoms are used to simulate the Cu electrode thin plate with a periodic structure of five layers (2x2 atoms per layer), showing a symmetric distribution. For the symmetric structure of the Bulk thin film obtained in the vacuum environment (without solution environment and vacuum layer structure), it is called the Bulk structure. To form a symmetric structure, the Bulk structure of the Cu(100) and (110) single-crystal electrode models consists of 16 atoms with a four-layer (2x2 atoms per layer) atomic model, and the Cu(111) electrode is a 12-atom three-layer (2x2 atoms per layer) atomic structure model. The direction perpendicular to the contact surface between the electrode and the electrolyte solution is set as the Z-axis direction.

[0041] The initial electron density output file was obtained by calculation. Taking the Slab structure of the Cu(100) single-crystal electrode model as an example, the following series of electron density grids can be obtained: 40 40 420

[0043] 1.0683074932e+05 8.9518159787e+04 5.3854463158e+04 2.5009796367e+04 9.8841719396e+03

[0044] 3.6648752188e+03 1.5420069521e+03 8.0849986412e+02 5.1404189136e+02 4.1077833956e+02

[0045] 3.8214613876e+02 4.1077833956e+02 5.1404189136e+02 8.0849986412e+02 1.5420069521e+03

[0046] 3.6648752188e+03 9.8841719396e+03 2.5009796367e+04 5.3854463158e+04 8.9518159787e+04

[0047] 1.0683074932e+05 8.9518159787e+04 5.3854463158e+04 2.5009796367e+049.8841719396e+03

[0048] 3.6648752188e+03 1.5420069521e+03 8.0849986412e+02 5.1404189136e+024.1077833956e+02

[0049] 3.8214613876e+02 4.1077833956e+02 5.1404189136e+02 8.0849986412e+021.5420069521e+03

[0050] ……

[0051] The electron density of a 40×40×420 spatial grid. Similarly, electron density files corresponding to simulated structures under various different environments can be obtained.

[0052] S2. Preprocess the initial output file of the electron density on the spatial coordinate axes to obtain the curve of the cross-sectional average electron density of the electrode structure along the Z-axis.

[0053] Using scripts to process the electron density with a three-dimensional spatial distribution, k-point sampling, and structural volume parameters, etc., and perform summation and averaging on the electron density in the same plane perpendicular to the Z-axis. Taking the position of the atoms in the middle layer of the electrode structure as the 0 point, the curve of the plane-averaged electron density is symmetrically distributed, and the electron density distributions of the electrode structure models with different crystal planes are as Figure 3 shown.

[0054] By calculating the plane-averaged electron densities of the Slab structure and the Bulk structure of the Cu electrodes on each crystal plane, further divide the structure into intra-atomic-layer and inter-layer regions. Specifically, knowing the coordinates of each atomic layer in the Z-axis direction and the model volume parameters in the calculation model, calculate the distance d between adjacent atomic layers in the structure; divide the atomic layer spacing into 4 equal parts on average, and the two side parts belong to the intra-layer regions of the corresponding adjacent atomic layers respectively, and the middle two equal parts are combined and called the inter-layer region between the two atomic layers.

[0055] Using parameters such as the atomic layer spacing and the structure volume of the structure, and integrating the electron density in their respective regions by using calculation scripts to obtain the total number of electrons in the intra-layer and inter-layer regions, and finally calculate the proportion of the number of electrons in each region to the total number of electrons in the entire structure, and draw the distribution diagram of the proportion of the number of electrons in each divided region.

[0056] The proportion of the number of electrons in the intra-layer and inter-layer regions between the atomic layers of the Bulk structure is the same. Normalizing it to a 5-layer structure identical to the Slab structure yields the proportion of the number of electrons in the intra-layer and inter-layer regions of the corresponding structure. By plotting, the distribution of the proportion of the number of electrons in the intra-layer and inter-layer regions of each atomic layer of the Slab structure and the Bulk structure can be obtained, as Figure 4 shown. The vertical axis in the figure represents the value of the proportion of the number of electrons in the region to the total number of electrons in the structure, and the horizontal axis is the various divided regions of the marked 5-layer atomic model structure: the white region is the intra-layer region of each atomic layer, the light gray region is the inter-layer region of each atomic layer, and the dark gray on both sides represents the outer region of the atomic layer structure of the electrode. The proportion of the number of electrons in each divided region of the Slab structure of the Cu(110), (100), and (111) planes is marked by geometric figures of three different grayscales, while the proportion of the number of electrons in the inter-layer and intra-layer regions of the atomic layers of the Bulk structure of the three crystal planes is represented by short horizontal lines of the corresponding grayscales.

[0057] Through the proportion of the number of electrons in the intra-layer and inter-layer regions of the Slab and Bulk structures of single-crystal Cu electrodes with different crystal planes, the electron distribution differences between the Cu(110) structure and the other two crystal planes can be intuitively and clearly observed: there is an obvious transfer of electrons between the outermost layer and the second outermost layer in the Slab structure of the Cu(110) plane. The higher proportion of the number of electrons in the inter-layer region of the Cu(110) plane can lead to a stronger attraction between adjacent atomic layers. Therefore, through this analysis method, the Cu(110) plane structure of the metal Cu electrode with better corrosion resistance can be quickly screened out.

[0058] Example 2: Similarly, taking metal Cu as an example, an electrode / electrolyte interface model is established based on the JDFTx first-principles calculation software for calculation. The difference is that the Slab structures of the single-crystal electrode models of the Cu(110), Cu(100), and Cu(111) planes constructed consist of 7 atomic layers.

[0059] Similarly, by obtaining the distribution of the average electron density of the Slab structure of the Cu electrode of each crystal plane along the Z-axis and finally dividing the intra-layer and inter-layer regions, the distribution map of the proportion of the number of electrons in each region can also be obtained, as Figure 5 shown. When the electrode structure is increased to a 7-layer atomic model, the corresponding result also shows that the proportion of the number of electrons in the inter-layer of the Cu(110) plane structure is the highest among the three planes, and the outermost atomic layer of Cu(110) shows the largest transfer amount of the number of electrons from the intra-layer region to the inter-layer. It can be seen that as the number of atomic layers of the Cu electrode structure increases, the same screening method can also be used to obtain effective analysis conclusions.

[0060] Example 3: In this example, a single-crystal Ag electrode / electrolyte interface model was re-simulated and established with metallic Ag as the object, and the first-principles related calculations were carried out similarly. Similarly, the distribution of the cross-sectional average electron density of the Slab structure along the Z-axis can be obtained based on the initial electron density output file, and the intra-layer and inter-layer regions can be divided. Finally, the percentage of the number of electrons in each region in the total number of electrons in the structure can be obtained for analysis and comparison.

[0061] Metallic Ag and Cu are metals in the same main group and both have a face-centered cubic (FCC) structure. The diffusion behavior of Ag / Ag(110) is very similar to that of Cu / Cu(110), and the Ag(110) surface is also chemically similar to the Cu(110) surface. By establishing a model for metallic Ag with similar characteristics to Cu as the electrode and using this screening method for calculation and comparison, the corresponding conclusions can also be obtained. For example Figure 6 , the results show that the analysis and calculation conclusions of metallic Ag can correspond well with those of Cu. It can be seen that this rapid screening method can be effectively applied to the coinage metals.

[0062] The rapid screening method for the corrosion-resistant crystal planes of the coinage metals provided by the present invention innovatively divides the intra-layer and inter-layer regions of the atomic layer of the first-principles calculation model, can more efficiently quantify the electron density of the coinage metal structure, and finally obtain a simple and clear distribution map of the percentage of the number of electrons, effectively presenting the difference in the electron density distribution caused by the structural change, and outputting the calculation results for different differential structures such as the Bulk vacuum structure model, so as to conduct effective visual comparison, and then quickly judge the crystal plane structure with better corrosion resistance.

[0063] The above has described the embodiments of the present invention in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made according to the purpose of the invention of the present invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent replacement methods. As long as they meet the invention purpose of the present invention and do not deviate from the technical principle and inventive concept of the present invention, they all belong to the protection scope of the present invention.

[0064] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rapid screening method for the corrosion-resistant crystal planes of copper group metals, characterized in that, It includes the following steps: S1. Based on the JDFTx calculation software, use a layered flat plate model to simulate and establish an electrochemical interface, perform an initial calculation on the coinage metal model, and obtain the output results of the structural calculation; obtain the electron density distribution file at each position in the spatial coordinate axes (x, y, z) after the corresponding k-point grid division in the output file; S2. Based on the initial electron density distribution file, use a calculation script to establish a distribution curve of the average electron density along the Z axis; S3. Based on the distribution curve of the electron density along the Z axis obtained in S2, divide the atomic layer structure of the model into intra-layer and inter-layer regions; S4. Analyze the changes in the electron density in the inter-layer and intra-layer regions, and judge the corrosion-resistant dissolution performance of the coinage metal electrode structure by the proportion of the number of electrons in the inter-layer.

2. The rapid screening method for the corrosion-resistant crystal planes of copper group metals according to claim 1, characterized in that: The establishment of the distribution curve of the average electron density along the Z axis by using the calculation script: Preprocess the initial electron density distribution file of the spatial coordinate axes (x, y, z), and know the electron density distribution corresponding to a×b×c spatial grid points; sum and average the electron density on the plane perpendicular to the Z axis, that is, convert the data point set of a series of spatial a×b×c into an m×c two-dimensional matrix; take the position of the middle-layer atom of the electrode structure as the 0 point, and connect the surface-averaged electron density sites distributed along the Z axis to obtain the distribution curve of the electron density along the Z axis.

3. The rapid screening method for the corrosion-resistant crystal planes of copper group metals according to claim 1, characterized in that: The division of the atomic layer structure of the model into intra-layer and inter-layer regions includes: Know the coordinates of each atomic layer in the Z axis direction of the calculation model and the volume parameters of the model, and calculate the distance d between adjacent atomic layers in the structure accordingly; divide the atomic layer spacing into 4 equal parts on average, and the two side parts belong to the intra-layer regions of the corresponding adjacent atomic layers respectively, and the middle two equal parts are combined and called the inter-layer region of the two atomic layers.

4. The rapid screening method for the corrosion-resistant crystal planes of copper group metals according to claim 2, characterized in that: The analysis of the changes in the electron density in the inter-layer and intra-layer regions includes: Sum the electron densities of two adjacent sites on the left and right sides of the division critical line respectively, and reallocate the electron densities of these two sites according to the ratio of their respective distances from the critical line; according to the distribution of the electron density along the Z axis and the volume parameters of the structure, integrate the electron density of each divided region to obtain the total number of electrons in the corresponding region; calculate the proportion of the number of electrons in each region to the total number of electrons in the entire structure, and present it by drawing.

5. The rapid screening method for the corrosion-resistant crystal planes of copper group metals according to claim 2, characterized in that: The preprocessing of the initial electron density distribution file of the spatial coordinate axes (x, y, z) includes: Extract the coordinates and perform calculation processing on the point set in the model in the form of a python program file.

6. The rapid screening method for the corrosion-resistant crystal planes of copper group metals according to any one of claims 1 to 5, characterized in that: The rapid screening method is also applicable to the simulation and establishment of an electrochemical interface for the Bulk structure model, and study the corrosion resistance of different crystal planes of coinage metals for comparative analysis and calculation.

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