High-entropy alloy catalyst oxygen evolution reaction overpotential calculation method based on preferred occupation

Abstract

The invention provides a high-entropy alloy catalyst oxygen evolution reaction overpotential calculation method based on preferred occupancy, which comprises the following steps of: establishing a high-entropy alloy atom distribution supercell model based on occupancy fractions of various component elements of a high-entropy alloy on sublattices, and performing crystal structure relaxation; constructing a slab model according to the optimized structure model, and performing R2 optimization; calculating Gibbs reaction free energy change and site change of three intermediates on different types of adsorption sites, and selecting catalytic sites to obtain tendency elements of different intermediates; preliminarily screening out a first neighbor atom combination covering different intermediate tendency elements on the slab catalytic surface; optimal catalytic site combinations of different intermediates are obtained, the overpotential for completing the catalytic reaction is the lowest, and the lowest overpotential and the average overpotential of the optimal catalytic site combinations are calculated. According to the method, a theoretical calculation model can be more accurately constructed based on preferential occupation, so that the overpotential of the high-entropy alloy OER can be accurately predicted.

Description

Technical Field

[0001] The invention relates to the technical field of oxygen evolution reaction (OER) of high entropy alloy catalysts, in particular to a method for calculating overpotential of oxygen evolution reaction of high entropy alloy catalysts based on preferential site occupancy. Background Art

[0002] OER, as the anodic reaction of electrocatalytic water decomposition, requires the participation of four electrons. The efficiency of water electrocatalytic decomposition is mainly limited by the high kinetic overpotential of anodic OER. Therefore, overcoming the large energy barrier and reducing the overpotential are key requirements for designing high-performance electrocatalysts. Noble metal-based oxides IrO2 and RuO2 are currently practical electrocatalysts, however, limited availability, high cost and low durability severely restrict their widespread application. Therefore, it is imperative to develop efficient and cost-effective catalysts to promote the development of water splitting applications.

[0003] High entropy alloys (HEAs), also known as multi-principal alloys (MPEAs), are characterized by equal or nearly equal mole fractions of principal elements. The most obvious electrocatalytic effect of HEAs is that the number of active sites increases with the growth of surface sites due to different combinations of elements. The large number of different active sites on the catalytic surface provides different reaction types. As the number of active sites increases, the probability of encountering highly catalytically active sites also rises significantly. Therefore, HEAs may show greater catalytic potential compared with single metals or binary alloys. In recent years, the application of HEAs as catalysts in the field of OER has attracted widespread attention. The CoFeMoNi HEA catalyst exhibits an extremely low overpotential of 250mV at a current density of 10mA / cm2, and the catalytic activity is 89mV lower than that of the state-of-the-art IrO2 catalyst. HEAs / HEAs catalysts are significantly better than commercial noble metal RuO2 catalysts. Therefore, HEAs catalysts have shown great potential, exceeding the catalytic activity of noble metal-based catalysts, and have great economic value in industry.

[0004] However, the exploration of HEAs as electrocatalysts is still in its early stages, especially regarding the design and regulation strategies to improve catalytic performance. This is mainly because the synergistic effects of different elements in HEAs-based catalysts make the catalytic mechanism unclear. Considering that experimental screening is time-consuming and costly, reasonable theoretical calculations / predictions play a key role in the development of HEAs-based catalysts. Among the limited HEAs catalysts, CoFeGaNiZnHEA has been characterized quite comprehensively, and some available experimental data for OER catalysis have been obtained, such as Aditi et al. homogenizing FCC_CoFeGaNiZnHEA at 1273K. In addition, Zn atoms have an unusually low d-band center energy in CoFeGaNiZn HEA, making it worthy of attention in OER mechanism studies.

[0005] Therefore, using CoFeGaNiZn HEA as a research system can provide precise information for building theoretical models and verifying their reliability. This helps to explore the potential OER mechanism of HEAs more accurately. In addition, the screening of HEAs-based catalysts relies heavily on a reliable catalytic "material library". Density functional theory (DFT)-based calculation methods are conducive to determining the actual active sites of catalysis, thereby gaining a deeper understanding of the OER mechanism. Establishing a reliable atomic distribution of HEAs is a prerequisite for accurate predictions. Although it is generally believed that the constituent atoms are randomly distributed throughout the lattice, some HEAs have recently shown ordered behavior. If a model is based on an unreasonable disordered crystal structure, that is, the atoms on the lattice are completely randomly distributed, it may not reveal certain unique or potential catalytic properties. For example, based on first-principles calculations, the ordered CuFeNiPtRh HEA exhibits excellent electrocatalytic activity and CO tolerance for ethanol oxidation reaction (EOR) compared with the disordered CuFeNiPtRh HEA. Therefore, when calculating catalytic performance, if it is assumed that all metal atoms occupy the entire lattice randomly or completely randomly, using quasi-random structure (SQS) or coherent potential approximation (CPA) simulations, some catalytic properties may be overlooked.

[0006] In fact, due to the differences in constituent atoms and sublattices, it is inevitable that there will be occupancy preferences in sublattices or even heterogeneous phase structures. In our opinion, under certain composition and heat treatment temperature, the occupancy preferences can be described by the site occupation fractions (SOFs), and they can be quantitatively characterized, so as to further reasonably predict various properties. Therefore, it is necessary to determine the details of the constituent atoms distributed on the sublattice, including the local area and the entire lattice.

[0007] Our previous work utilized an in-house built thermodynamic database involving the temperature-dependent Gibbs free energy of formation of end-group compounds to predict the SOFs of various HEAs. In this work, the site-occupancy preference configurations of FCC_CoFeGaNiZn HEAs were obtained based on the predicted SOFs, which enabled us to more reasonably and reliably predict the adsorption energies at different sites of HEAs. Therefore, a deeper understanding of the adsorption sites and catalytic mechanisms of FCC_CoFeGaNiZn HEAs in OER catalysis can be achieved based on a reasonable atomic distribution model. In this paper, the free energy changes and position changes of three intermediates, *OH, *O and *OOH, on 171 adsorption sites on the surface of FCC_CoFeGaNiZn HEAs during relaxation were systematically studied. In addition, we elucidated the free energy and adsorption site changes of three intermediates in HEAs in OER, the morphological changes on the catalytic surface, the actual active sites of catalysis, the scaling relationship, and calculated the average overpotential on the surface of HEAs. The purpose of this invention is to establish a reasonable and general method to explore and describe the OER mechanism of HEAs, so as to screen and improve the catalysts of HEAs. Summary of the invention

[0008] The purpose of the present invention is to propose a method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalysts based on preferential occupancy, which can more accurately construct a theoretical calculation model based on preferential occupancy, so as to accurately predict the overpotential of high entropy alloy OER. This method can provide a reliable calculation method for calculating the overpotential of OER of other high entropy alloy systems, thereby screening out high entropy alloy catalysts with superior performance.

[0009] To achieve the above object, the technical solution of the present invention is: a method for calculating the overpotential of oxygen evolution reaction of a high entropy alloy catalyst based on preferential occupancy, comprising the following steps:

[0010] Step S1: Modeling is performed based on the phase structure of the high entropy alloy phase, phonon spectrum calculation is performed by density functional perturbation theory, temperature-dependent Gibbs free energy is obtained, a formatted Gibbs free energy database of terminal compound formation is constructed, and the occupancy fractions of various constituent elements of the high entropy alloy on different types of sublattices are calculated based on the database;

[0011] Step S2: Based on the occupancy fraction data of various constituent elements on the sublattice, an n×n×n cell expansion is performed to establish a high entropy alloy atomic distribution block supercell model, and based on the total energy minimization principle, the crystal structure relaxation is performed on the structural model of the actual distribution of atoms in the high entropy alloy to obtain an optimized structural model;

[0012] Step S3: According to the optimized structural model, the average d-band center energy of each component element of the high entropy alloy is calculated, and the element with the highest average d-band center energy is obtained as the element with significant catalytic potential, and then the closest packed surface of the optimized structural model is cut, and the surface with the most atoms containing the element with the highest average d-band center energy is selected as the slab catalytic surface, and the remaining n-1 closest packed surfaces in the cycle are placed under the slab catalytic surface to construct an n-layer slab model including a vacuum layer;

[0013] Step S4: using the selective dynamics method to perform R2 optimization on the constructed n-layer slab model including the vacuum layer, during which the atoms in the bottom n-1 layers are locked and the atoms on the surface are released;

[0014] Step S5: Calculate the Gibbs reaction free energy change ΔG of the three intermediates *OH, *O and *OOH on different types of adsorption sites *OH , ΔG *O , ΔG *OOH and site changes, selecting the site type with the largest change range of Gibbs reaction free energy of the three intermediates *OH, *O and *OOH as the catalytic site; the different types of adsorption sites include top, bridge and hollow sites, wherein the hollow sites include FCC-hollow and HCP-hollow sites;

[0015] Step S6: calculating the average Gibbs reaction free energy changes of the three intermediates at the catalytic sites of different elements to obtain the preferred elements of different intermediates;

[0016] Step S7: Select the preferred element of each intermediate, and preliminarily screen out the first nearest neighbor atom combination covering the preferred elements of different intermediates on the slab catalytic surface;

[0017] Step S8: Calculate the change in Gibbs reaction free energy at each atomic site of the three intermediates in the initially screened atomic combination, obtain the optimal catalytic site combination of different intermediates, and further obtain the minimum overpotential for the completion of the catalytic reaction, then calculate the minimum overpotential of each optimal catalytic site combination, and add and average the overpotentials of all combinations to obtain the average overpotential.

[0018] The present invention realizes the calculation of the OER overpotential of a high entropy alloy catalyst based on the atomic preferential site occupation behavior.

[0019] Preferably, the crystal structure relaxation in step S2 is specifically R3 optimization: optimizing the unit cell volume, unit cell shape and atomic position.

[0020] Preferably, the step S3 is specifically:

[0021] A method for obtaining slab catalytic surfaces from different types of closest-packed surfaces using the d-band center theory based on first principles: the closest-packed surface of the optimized structure is sectioned to obtain n 2 (n is the cell expansion multiple) layers of the most densely packed surface, and n consecutive most densely packed surfaces constitute a cycle. When n tends to infinity, the physical and chemical properties of each most densely packed surface tend to be consistent. However, due to limited computing resources, the expansion multiple of the unit cell is limited, which leads to large differences in the physical and chemical properties of different most densely packed surfaces. Therefore, the d-band center theory is used to select a surface with significant catalytic potential from n types of most densely packed surfaces as a slab catalytic surface, where the calculation formula of the d-band center is shown in formula (1):

[0022]

[0023] Where x is energy, ρ(x) is the energy-related electronic state density function, E f is the energy at the Fermi level. By calculating the d-band center energy of different atoms of different elements in the optimized structure and taking the average of the d-band center energy of each element, the element with significant catalytic potential (the element with the highest d-band center energy) is obtained, and the most densely packed surface containing the most elements is selected as the slab catalytic surface.

[0024] Preferably, the step S5 is specifically:

[0025] For metal or alloy catalysts, there are four types of adsorption sites on the catalytic surface, namely top, bridge, FCC-hollow and HCP-hollow sites. Top sites are located above atoms. Bridge sites are located between two atoms. FCC-hollow sites are located above between three atoms, while the site has no atoms in the lower layer. HCP-hollow sites are located above between three atoms, but there are atoms in the lower layer of the site.

[0026] First, three different adsorbed molecules (intermediates) are placed at different adsorption sites (top, bridge and hollow sites) of the optimized slab model for R2 optimization, and the total energy of the system with different intermediates adsorbed at different sites is obtained respectively; then, the Gibbs reaction free energy change and site relaxation change of different intermediates at different sites are calculated, wherein the optimization process only allows the adsorbed substance and the atomic layer affected by the adsorbed substance in the upper layer of the slab model to relax, and the unaffected atoms in the lower layer of the slab model remain fixed; finally, the Gibbs reaction free energy change range of all optimized intermediates at different types of sites is analyzed, and the site type that can provide the largest Gibbs reaction free energy change range for the three intermediates *OH, *O and *OOH is selected as the catalytic site of the three intermediates (considering the limited computing resources, all intermediates use the same type of catalytic site). The calculation of the adsorption energy of the three intermediates is shown in formulas (2), (3) and (4):

[0027]

[0028] In this model, under the conditions of U = 0 V (where U is the electrode potential relative to the CHE) and PH2 = 1 bar, e - +H + The Gibbs free energy is equal to 1 / 2H2. *OH , ΔE *O , ΔE *OOH are the adsorption energies of the intermediates *OH, *O and *OOH, respectively; E* is the energy of the slab model of the (111) crystal plane in HEA; E *OH 、E *O and E *OOH are the electron energies of the slab model with intermediates *OH, *O and *OOH, is the energy of H2O at 298.15K, is the energy of H2 at 298.15K.

[0029] The Gibbs free energy change (ΔG) for each step involving an electron transfer *OH , ΔG *O and ΔG *OOH ) is calculated as shown in formulas (5), (6) and (7):

[0030] ΔG=ΔE+ΔZPE-TΔS+ΔG U +ΔG pH (5)

[0031] ΔG U =-eU (6)

[0032] ΔG pH=-kTln[H + ]=kTln10×pH (7)

[0033] where ΔG is used to refer to ΔG *OH or ΔG *O or ΔG *OOH , ΔE is the adsorption energy, ΔZPE is the zero-point energy correction, and ΔS is the entropy change. ΔZPE and ΔS can be calculated by DFT calculations and standard thermodynamic data. The free energy of gaseous water is calculated at 0.035 Bar because this pressure corresponds to the equilibrium pressure with liquid water at 298 K. Under these conditions, the free energy of gaseous water is equal to the free energy of liquid water. Since DFT calculations generally cannot adequately describe the high-spin ground state of oxygen molecules, the free energy of O2 molecules is calculated by the chemical reaction 2G(H2O)-2G(H2)-G(O2)=-4.92eV. The vibrational frequencies of the adsorbed species are used to determine the ΔZPE and ΔS values ​​of *OH, *O, and *OOH. During the calculation, the slab model atoms were fixed, and only the atoms of the adsorbed species were allowed to relax. The temperature was set to 298.15K. ΔG U is the external electric field energy, ΔG U = -eU, where U is the potential applied by the electrode and e is the elementary charge. ΔG pH is the corrected value of the free energy at any pH value, where k is the Boltzmann constant, and for acidic conditions, pH is set to 0, [H + ] is the concentration of hydrogen ions.

[0034] Preferably, the number of atomic layers in the upper layer of the slab model affected by the adsorbed substance is determined by observing the charge transfer between the adsorbed substance and the slab model by calculating the differential charge density of the adsorbed substance adsorbed on the slab model, so as to judge whether the adsorbed substance has an effect on the upper layers of atoms in the slab model. For example, if the adsorbed substance only affects two layers of atoms on the upper surface of the slab model, the adsorbed substance and the two layers on the upper surface of the slab model are relaxed, while the bottom n-2 layers of atoms in the slab model remain fixed.

[0035] Preferably, the step S6 is specifically:

[0036] Method for determining the tendency elements of different intermediates: Under the same overpotential path, different intermediates may exist at different catalytic sites. It is necessary to calculate the free energy change values ​​(ΔG) of different intermediates at different element catalytic sites on the slab catalytic surface, and then average the free energy change values ​​of all atoms of different elements on the surface. According to the Sabatier principle, the adsorption strength of elements on intermediates that is too strong or too weak is not conducive to the catalytic reaction. Therefore, the element that minimizes the average free energy difference of the intermediates and makes its average value as close to 0eV as possible is called the tendency element of the intermediate, that is, the element that helps to reduce the overpotential of the intermediate.

[0037] Preferably, the step S7 is specifically:

[0038] The method for screening different atomic combinations participating in OER is: first, the atomic combination must contain the tending elements of different intermediates, and second, the atomic combination only considers adjacent atoms (in the same overpotential path, it is challenging for the reactions of three intermediates to cross multiple strongly adsorbed hollow sites, which hinders their transfer to distant sites).

[0039] Preferably, the step S8 is specifically as follows:

[0040] For the atomic combination of OER that was initially screened, considering that the environments around different atoms of HEA are different, there may be interactions between atoms, which may cause the Gibbs free energy change of the intermediate on its preferred element to be not necessarily the smallest. Therefore, it is necessary to further calculate the Gibbs free energy change of different intermediates at different sites to find the best route with the lowest energy rise of each step of the elementary element, so that the overpotential of the OER catalytic reaction is the lowest. The calculation of the overpotential of the three intermediates is shown in formula (8):

[0041] η OER = max{ΔG1,ΔG2,ΔG3,ΔG4} / e -1.23, (8)

[0042] Among them, ΔG1 is the external electric field energy required for the adsorption of the *OH intermediate in the first step of the OER reaction on the slab model, ΔG1 = ΔG *OH ; ΔG2 is the external electric field energy required for the *O intermediate to adsorb on the slab model after the *OH intermediate in the second step of the oxygen evolution reaction is desorbed on the slab model, ΔG2 = ΔG *O -ΔG *OH ; ΔG3 is the external electric field energy required for the *OOH intermediate to adsorb on the slab model after the *O intermediate desorbs on the slab model in the third step of the OER reaction, ΔG3 = ΔG *OOH -ΔG *O ; ΔG4 is the fourth step of OER reaction H+ After desorption on the slab model, the external electric field energy required for O2 generation is ΔG4 = 4.92-ΔG *OOH ; e is the elementary charge. According to the Nernst equation, at pH = 0, the equilibrium potential of OER is measured to be 1.23 V (relative to CHE), and the theoretical overpotential (η) is equal to the maximum gap (the step with the largest potential in the four steps of the OER reaction) minus the ideal value of 1.23.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention can more accurately construct a theoretical calculation model based on preferential site occupancy, and can accurately predict the overpotential of high entropy alloy OER, thereby reducing experimental costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the thermodynamic model of the prototype AuCu3 of the FCC-structured end group compound of the preferred embodiment of the present invention;

[0046] Figure 2 Schematic diagram of thermodynamic calculation pathway of FCC_CoFeGaNiZn high entropy alloy with FCC structure in a preferred embodiment of the present invention, wherein ①=②+③;

[0047] Figure 3 A trend diagram showing the change in the site fraction of various constituent elements of the FCC_CoFeGaNiZn high entropy alloy of the preferred embodiment of the present invention with temperature;

[0048] Figure 4 A schematic diagram of the 3×3×3 supercell sublattice occupancy configuration of a FCC_CoFeGaNiZn high entropy alloy constructed using 1273K occupancy fraction values ​​according to a preferred embodiment of the present invention;

[0049] Figure 5 A schematic diagram of d-band center energy distribution of five elements of FCC_CoFeGaNiZn high entropy alloy constructed using 1273K occupancy fraction values ​​in a preferred embodiment of the present invention;

[0050] Figure 6 Schematic diagram of different (111) crystal plane sections of a 3×3×3 supercell FCC_CoFeGaNiZn high entropy alloy at 1273K occupancy fraction in a preferred embodiment of the present invention;

[0051] Figure 7 This is a schematic diagram of a slab model of a FCC_CoFeGaNiZn high entropy alloy (111) after crystal plane sectioning in a preferred embodiment of the present invention;

[0052] Figure 8A schematic diagram of four types of adsorption sites on the high entropy alloy catalytic surface according to a preferred embodiment of the present invention;

[0053] Fig. 9 A schematic diagram of different adsorption sites on the surface of a FCC_CoFeGaNiZn high entropy alloy slab model according to a preferred embodiment of the present invention;

[0054] Fig.10 Schematic diagram of the site and energy change distribution of the intermediate *OH of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst of the preferred embodiment of the present invention after relaxation at three different types of different adsorption sites;

[0055] Fig.11 Schematic diagram of the site and energy change distribution of the intermediate *O of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst of the preferred embodiment of the present invention after relaxation at three different types of different adsorption sites;

[0056] Fig.12 Schematic diagram of the site and free energy change distribution of the intermediate *OOH of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst of the preferred embodiment of the present invention after relaxation at three different types of different adsorption sites;

[0057] Fig.13 A schematic diagram showing the distribution of the free energy variation range of three intermediates of the OER on three different types of adsorption sites of the FCC_CoFeGaNiZn high entropy alloy catalyst of the preferred embodiment of the present invention;

[0058] Fig.14 A schematic diagram showing the distribution of average free energy change values ​​of three different intermediates of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst on five different elements in a preferred embodiment of the present invention;

[0059] Fig.15 A diamond configuration of four site clusters of a preferred embodiment of the present invention;

[0060] Fig.16 A schematic diagram of a reaction combination of three intermediate-prone elements at different top sites of the FCC_CoFeGaNiZn high entropy alloy catalyst for OER in a preferred embodiment of the present invention;

[0061] Fig.17 A schematic diagram showing the distribution of free energy change values ​​of three intermediates of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst of the preferred embodiment of the present invention at different sites of the second reaction combination;

[0062] Fig.18Schematic diagram of the change in overpotential of the OER of the FCC_CoFeGaNiZn high entropy alloy catalyst in the optimal reaction combination of the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0064] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0065] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0066] In this embodiment, the FCC_CoFeGaNiZn high entropy alloy with FCC structure is taken as an example to provide a method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy. Figure 1-18 , including the following steps:

[0067] Step S1: FCC single-phase structure based on high entropy alloy, prototype AuCu3 Figure 1 . Construct the corresponding sublattice model AB3 and establish the end group compounds of FCC_CoFeGaNiZn high entropy alloy, which includes a total of 25 end group compounds, such as Figure 2 As shown;

[0068] The corresponding relationship between the Gibbs free energy of the terminal compound and the temperature was obtained by calculating the phonon spectrum based on density functional perturbation theory. According to the general thermodynamic fitting formula of the calculated phase diagram (CALPHAD), G(T) = A + B × T × lnT + C × T^ 2 +D×T^ 3 +E×T^ -1 +F×T, where A, B, C, D, E, and F are constants to be fitted, and T is temperature (K). MATLAB is used to fit the constants in the functional relationship, and then the free energy of the element in the ground state is subtracted and written into the formatted (.TDB) generated Gibbs free energy (ΔG) database. For example, the temperature-dependent Gibbs free energy expression of the element is: FUNCTION SERCO 1.0

[0069] -681500-14.54*T*LN(T)-0.009912*T**2+0.1033E-07*T**3-3.081E+04*T**(-1)+71.78*T; The expression of the end group is: PARAMETER G(FCC,CO:FE;0)1.0

[0070] -755700-12.13*T*LN(T)-0.009343*T**2+9.877E-07*T**3-3.39E+04*T**(-1)+56.47*T-0.25*SER CO#-0.75*SERFE#. Then, based on the database, the occupancy fraction of the element on the sublattice is calculated using Pandat software or Thermo-Calc. The occupancy fraction of each element on the sublattice at different temperatures from low temperature 300K to high temperature 1500K is shown in Figure 2. Figure 3 .

[0071] Step S2: Using the obtained temperature-dependent occupancy fraction data of different elements in the FCC_CoFeGaNiZn high entropy alloy on the sublattice, an atomic arrangement model of the FCC_CoFeGaNiZn high entropy alloy phase at 1273K is constructed, see Figure 4 Based on the principle of total energy minimization, the crystal structure relaxation (unit cell volume, unit cell shape, atomic position, stress tensor of the unit cell and the force exerted on the atoms) of the structural model of the actual distribution of atoms in the high entropy alloy is performed to obtain the optimized stable structural model.

[0072] Step S3: According to the optimized structural model, the d-band center energy of different atoms of different elements in the FCC_CoFeGaNiZn high entropy alloy is calculated, and the d-band center energy of each element is averaged to obtain the element with significant catalytic potential (the element with the highest average d-band center energy), such as Figure 5 As shown, Ga element exhibits the highest average d-band energy (1.655 eV) among the elements in CoFeGaNiZnHEA, which indicates that it is the most active element and the presence of Ga may have a potential positive impact on the environment of the surrounding local sites. Then the (111) plane of FCC_CoFeGaNiZn high entropy alloy was cut to obtain 9 layers of (111) planes, as shown in Fig. Figure 6 , since it is a 3×3×3 expansion cell, three consecutive (111) faces form a loop. We select the second layer (or fifth layer or eighth layer) with the most Ga atoms in the 9 (111) layers as the slab surface, and place the remaining two (111) faces in the loop under the slab surface, constructing a 3-layer, 108-atom and Vacuum layer flat plate model, see Figure 7.

[0073] Step S4: Using the Selective Dynamics method, the crystal structure of the constructed three-layer slab model including the vacuum layer is relaxed (R2 optimization: the unit cell shape and the atomic position are optimized). During the optimization process, the atoms of the bottom two layers are locked, and the atoms of the surface layer are released;

[0074] Step S5: Calculate the free energy change values ​​(ΔG) of the three intermediates (*OH, *O and *OOH) on different types of adsorption sites (top, bridge and FCC-hollow) *OH , ΔG *O and ΔG *OOH ) and site changes, the site type with the largest change range of Gibbs reaction free energy of the three intermediates *OH, *O and *OOH was selected as the catalytic site;

[0075] For FCC_CoFeGaNiZn high entropy alloy, there are three types of adsorption sites on the catalytic surface, namely top, bridge and FCC-hollow sites, see Figure 8 . Top sites are located above an atom. Bridge sites are located between two atoms. FCC-hollow sites are located above three atoms, while sites have no atoms in the lower layer.

[0076] Firstly, three different adsorbed molecules (intermediates) were placed on three different types of different adsorption sites of the optimized slab model for R2 optimization, and the total energy of the system with different intermediates adsorbed on different sites was obtained respectively; then, the free energy change and site relaxation change of different intermediates on different sites were calculated, in which the optimization process only allowed the adsorbed substances and surface atoms to relax, while the bottom two layers of atoms of the slab remained fixed; finally, the energy change range of all intermediates at different types of sites after optimization was analyzed, and the site type that could provide appropriate adsorption strength was selected as the catalytic site. The energy change range of the three intermediates is as follows: Figure 9-13 As shown, considering the limited computing resources, all intermediates are only considered to proceed at the top site.

[0077] Step S6: calculating the average Gibbs reaction free energy changes of the three intermediates at the catalytic sites of different elements to obtain the tendency elements of different intermediates;

[0078] Under the same overpotential path, different intermediates may exist at different catalytic sites. It is necessary to calculate the average Gibbs reaction free energy change of different intermediates at different element catalytic sites. According to the Sabatier principle, the adsorption strength of the element on the intermediate is too strong or too weak, which is not conducive to the catalytic reaction. Therefore, it is necessary to minimize the difference in the average Gibbs reaction free energy of different intermediates on different elements, and make its average value as close as possible to the slab free energy change (0eV). The elements that help reduce the overpotential of the intermediates are called tending elements. Fig.14 As shown, for *OH, the best element for the *OH intermediate is Zn, with Ni as a secondary choice. The average energy difference between the best Zn element and the second best Ni element is 0.124 eV, indicating that some Ni top sites may still have similar activities to those of Zn top sites. Therefore, the Ni element needs to be considered. The free energy difference of Co, Fe and Ga relative to Zn reaches 0.361 eV, indicating that the activity similarity of these three elements with the top site of Zn is limited. Similarly, the same method is applied to the other two intermediates, *O and *OOH. For the *O intermediate, Ga is the best element, while the free energy of the other four elements relative to Ga exceeds 0.350 eV. For the *OOH intermediate, the best element is Fe, and Co is the second best element with a free energy difference of 0.139 eV. The difference between the elements Ga, Ni and Zn and the best element Fe exceeds 0.336 eV.

[0079] Step S7: Select the tendency element of each intermediate, and preliminarily screen out the first nearest neighbor atom combination covering the tendency elements of different intermediates on the slab surface;

[0080] To screen different atomic combinations involved in the OER catalytic reaction, first, the atomic combination must contain the propensity elements of different intermediates, and second, the atomic combination only considers adjacent atoms (in the same overpotential path, it is challenging for the reaction of three intermediates to cross multiple strongly adsorbed hollow sites, which hinders their transfer to more distant sites, see Fig.15 Considering that the best element for the *OH intermediate is Zn, with Ni as a second choice, the best element for the *O intermediate is Ga, and the best element for the *OOH intermediate is Fe, with Co as the second best element, four atomic top sites are identified on the slab surface, and a total of fourteen site combinations are found, see Fig.16 .

[0081] Step S8: Calculate the change in Gibbs free energy at each atomic site of the three intermediates in the initially screened atomic combination, obtain the optimal catalytic site combination suitable for different intermediates, and further obtain the minimum overpotential for the catalytic reaction to be completed.

[0082] For the atomic combinations of the initially screened OER catalytic reaction, considering the different environments around different atoms of HEA, there may be interactions between atoms, resulting in the Gibbs free energy change of the intermediate on its preferred element not necessarily being the smallest. Therefore, it is necessary to further calculate the Gibbs free energy change of different intermediates at different sites. The energy change is as follows: Fig.17 As shown in Figure 1, the optimal route with the lowest energy rise of each unit is found to minimize the overpotential of the OER catalytic reaction. Fig.18 As shown, based on the overpotentials of 14 combinations, the calculated average overpotential is 0.349 V, which is closer to the experimental overpotential of 0.37 V (10 mA / cm2 current density) than the 0.28 V value using a special quasi-random structure (SQS).

[0083] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalysts based on preferential occupancy, characterized in that: The following steps are involved: Step S1: Modeling is performed based on the phase structure of the high entropy alloy phase, phonon spectrum calculation is performed by density functional perturbation theory, temperature-dependent Gibbs free energy is obtained, a formatted Gibbs free energy database of terminal compound formation is constructed, and the occupancy fractions of various constituent elements of the high entropy alloy on different types of sublattices are calculated based on the database; Step S2: Based on the occupancy fraction data of various constituent elements on the sublattice, an n×n×n cell expansion is performed to establish a high entropy alloy atomic distribution block supercell model, and based on the total energy minimization principle, the crystal structure relaxation is performed on the structural model of the actual distribution of atoms in the high entropy alloy to obtain an optimized structural model; Step S3: According to the optimized structural model, the average d-band center energy of each component element of the high entropy alloy is calculated, and the element with the highest average d-band center energy is obtained as the element with significant catalytic potential, and then the closest packed surface of the optimized structural model is cut, and the surface with the most atoms containing the element with the highest average d-band center energy is selected as the slab catalytic surface, and the remaining n-1 closest packed surfaces in the cycle are placed under the slab catalytic surface to construct an n-layer slab model including a vacuum layer; Step S4: using the selective dynamics method to perform R2 optimization on the constructed n-layer slab model including the vacuum layer, during which the atoms in the bottom n-1 layers are locked and the atoms on the surface are released; Step S5: Calculate the Gibbs reaction free energy change ΔG of the three intermediates *OH, *O and *OOH on different types of adsorption sites *OH , ΔG *O , ΔG *OOH and site changes, selecting the site type with the largest change range of Gibbs reaction free energy of the three intermediates *OH, *O and *OOH as the catalytic site; the different types of adsorption sites include top, bridge and hollow sites, wherein the hollow sites include FCC-hollow and HCP-hollow sites; Step S6: calculating the average Gibbs reaction free energy changes of the three intermediates at the catalytic sites of different elements to obtain the preferred elements of different intermediates; Step S7: Select the preferred element of each intermediate, and preliminarily screen out the first nearest neighbor atom combination covering the preferred elements of different intermediates on the slab catalytic surface; Step S8: Calculate the change in Gibbs reaction free energy at each atomic site of the three intermediates in the initially screened atomic combination, obtain the optimal catalytic site combination of different intermediates, and further obtain the minimum overpotential for the completion of the catalytic reaction, then calculate the minimum overpotential of each optimal catalytic site combination, and add and average the overpotentials of all combinations to obtain the average overpotential.

2. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The crystal structure relaxation in step S2 is specifically R3 optimization: optimizing the unit cell volume, unit cell shape and atomic position.

3. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The step S3 is specifically as follows: The d-band center energy of different atoms of different elements in the optimized structural model is calculated, and the d-band center energy of each element is averaged to obtain the average d-band center energy of each component element: Where x is energy, ρ(x) is the energy-related electronic state density function, E f is the energy at the Fermi level; Cut the most densely packed surface of the optimized structural model to obtain n 2 The layer of closest-packed surfaces, n is the cell expansion multiple, and n consecutive closest-packed surfaces constitute a cycle. The element with the highest average d-band center energy is taken as the element with significant catalytic potential, and the closest-packed surface containing the most of this element is selected as the slab catalytic surface.

4. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The R2 optimization in step S4 specifically involves optimizing the unit cell shape and atomic positions.

5. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential site occupancy according to claim 1, characterized in that: The step S5 is specifically: Firstly, three different intermediates were placed at different adsorption sites of the optimized slab model for R2 optimization, and the adsorption energy and Gibbs reaction free energy changes of different intermediates adsorbed at different sites were obtained by using the adsorption energy and Gibbs reaction free energy calculation formulas. Then the Gibbs reaction free energy changes and site relaxation changes of different intermediates at different sites are statistically analyzed, wherein the optimization process only allows the adsorbed substances and the atomic layers affected by the adsorbed substances in the upper layer of the slab model to relax, and the unaffected atoms in the lower layer of the slab model remain fixed; Finally, the variation range of Gibbs reaction free energy of intermediates on all optimized different types of sites was analyzed, and the site type that could provide the largest variation range of Gibbs reaction free energy of three intermediates *OH, *O and *OOH was selected as the catalytic site of the three intermediates; The calculation of the adsorption energy of the three intermediates is shown in formulas (2), (3) and (4): Where, ΔE *OH , ΔE *O , ΔE *OOH are the adsorption energies of the intermediates *OH, *O and *OOH, respectively, and E * is the energy of the slab model of the (111) crystal plane in the high entropy alloy, E *OH 、E *O and E *OOH are the electron energies of the slab model with intermediates *OH, *O and *OOH, is the energy of H2O at 298.15K, is the energy of H2 at 298.15K; The Gibbs free energy change ΔG for each step involving an electron transfer *OH , ΔG *O and ΔG *OOH The calculation of is shown in formulas (5), (6) and (7): ΔG=ΔE+ΔZPE-TΔS+ΔG U +ΔG pH (5) ΔG U =-eU (6) ΔG pH =-kTln[H + ]=kTln10×pH (7) where ΔG is used to refer to ΔG *OH or ΔG *O or ΔG *OOH , ΔE, ΔZPE and ΔS are the adsorption energy, zero-point energy correction and entropy change of the corresponding intermediates, respectively. The vibrational frequencies of the adsorbed species are used to determine the ΔZPE and ΔS values ​​of *OH, *O and *OOH. During the calculation process, the slab model atoms are fixed, and only the atoms of the adsorbed species are allowed to relax. The temperature T is set to 298.15K; ΔG U is the external electric field energy, U is the potential applied by the electrode, e is the elementary charge; ΔG pH is the corrected value of the free energy at any pH value, k is the Boltzmann constant, [H + ] is the concentration of hydrogen ions.

6. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 5, characterized in that: The number of atomic layers on the upper layer of the slab model affected by the adsorbed substance is determined by calculating the differential charge density of the adsorbed substance on the slab model to observe the charge transfer between the adsorbed substance and the slab model, so as to judge whether the adsorbed substance has an impact on the upper atomic layers of the slab model.

7. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The determination of the tendency elements of different intermediates in step S6 is specifically as follows: the free energy change values ​​of different intermediates at the catalytic sites of different elements on the slab catalytic surface are calculated respectively, and then the free energy change values ​​of all atoms of different elements on the surface are averaged respectively, so that the average free energy difference of the intermediates is minimized, and the element whose average value is as close to 0eV as possible is the tendency element of the intermediate.

8. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The step S7 preliminarily screens out the first nearest neighbor atomic combination covering different intermediate tendency elements on the slab catalytic surface based on the following principle: the screened atomic combination must contain the tendency elements of different intermediates, and the atomic combination only considers the atomic neighbors of the tendency elements of different intermediates.

9. The method for calculating the overpotential of oxygen evolution reaction of high entropy alloy catalyst based on preferential occupancy according to claim 1, characterized in that: The step S8 is specifically as follows: For the atomic combinations of oxygen evolution reaction that were initially screened, the Gibbs free energy changes of different intermediates at different sites were calculated to find the best route with the lowest energy rise of each element, so that the overpotential of OER is the lowest. The overpotentials of the three intermediates are calculated as shown in formula (8): or OER = max{ΔG1,ΔG2,ΔG3,ΔG4} / e -1.23 (8) Among them, ΔG1 is the external electric field energy required for the adsorption of the *OH intermediate in the first step of the OER reaction on the slab model, ΔG1 = ΔG *OH ; ΔG2 is the external electric field energy required for the *O intermediate to adsorb on the slab model after the *OH intermediate in the second step of the oxygen evolution reaction is desorbed on the slab model, ΔG2 = ΔG *O -ΔG *OH ; ΔG3 is the external electric field energy required for the *OOH intermediate to adsorb on the slab model after the *O intermediate desorbs on the slab model in the third step of the OER reaction, ΔG3 = ΔG *OOH -ΔG *O ; ΔG4 is the fourth step of OER reaction H + After desorption on the slab model, the external electric field energy required for O2 generation is ΔG4 = 4.92-ΔG *OOH ; e is the elementary charge.

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