阅读说明：本技术 一种模拟溶剂环境下催化剂表面催化反应机理的计算方法 (Calculation method for catalyst surface catalytic reaction mechanism under simulated solvent environment ) 是由 贺涛 ***·路易 郭令举 于 2019-09-18 设计创作，主要内容包括：本发明涉及一种模拟溶剂环境下催化剂表面催化反应机理的计算方法,所述计算方法包括将催化剂的表面体系模型划分为晶体周期结构、表面层和真空层,之后基于隐式溶剂模型利用密度泛函理论进行计算得到溶剂环境下催化剂表面催化反应机理；相较于传统的真空环境下的计算方法,本发明所述方法的计算结果更加准确,利用本发明所述方法能更深入的理解催化反应的微观机理,为实验改进和设计新型催化剂提供理论支撑。(The invention relates to a method for calculating a catalytic reaction mechanism on the surface of a catalyst in a simulated solvent environment, which comprises the steps of dividing a surface system model of the catalyst into a crystal periodic structure, a surface layer and a vacuum layer, and calculating by using a density functional theory based on an implicit solvent model to obtain the catalytic reaction mechanism on the surface of the catalyst in the solvent environment; compared with the traditional calculation method under the vacuum environment, the method has the advantages that the calculation result is more accurate, the microscopic mechanism of catalytic reaction can be deeply understood by using the method, and theoretical support is provided for experimental improvement and novel catalyst design.)

1. A calculation method for simulating a catalytic reaction mechanism on the surface of a catalyst in a solvent environment is characterized by comprising the steps of dividing a surface system model of the catalyst into a crystal periodic structure, a surface layer and a vacuum layer, and calculating by using a density functional theory based on an implicit solvent model to obtain the catalytic reaction mechanism on the surface of the catalyst in the solvent environment.

2. The calculation method of claim 1, wherein the method for calculating the catalytic reaction mechanism of the catalyst surface in the solvent environment based on the implicit solvent model by using the density functional theory comprises calculating the most stable adsorption configuration of reactant and product molecules on the catalyst surface in the solvent environment by using the density functional theory, so as to obtain the catalytic reaction mechanism of the catalyst surface in the solvent environment;

preferably, the catalyst comprises a metallic catalytic material and a semiconducting catalytic material;

preferably, the metal catalytic material comprises any one or a combination of at least two of Au, Pt, Ag, Cu or Ni;

preferably, the semiconductor catalytic material comprises any one of or a combination of at least two of a binary oxide, a ternary oxide or a sulfide;

preferably, the semiconducting catalytic material comprises BiOCl;

preferably, the thickness of the vacuum layer is > 10 angstroms;

preferably, the number of layers of the surface layer is > 4 layers.

3. The computing method of claim 1 or 2, wherein the implicit solvent model comprises any of Onsager, PCM, CPCM, IPCM, SCIPCM, COSMO, SMD, or SMx;

preferably, the solvent comprises any one of water, ethanol, acetone, acetonitrile or benzene or a combination of at least two thereof.

4. The calculation method according to any one of claims 1 to 3, further comprising, before the partitioning of the catalyst surface system model, determining the exposed crystal planes under study;

preferably, the exposed crystal plane includes any one of (001), (101), (110), or (111) or a combination of at least two thereof.

5. The method of any one of claims 1 to 4, wherein the method of computing using density functional theory comprises generalized gradient approximation and/or local density approximation;

preferably, the functional form of the generalized gradient approximation comprises any one of PW91, PBE or BLYP;

preferably, the software for local density approximation comprises VASP, Dmol³Either Gaussian or Q-Chem.

6. The method according to any one of claims 1 to 5, characterized in that it comprises the steps of:

(1) determining crystal structure information of the catalyst, and then carrying out geometric structure optimization to obtain the lowest energy structure of the bulk material of the catalyst;

(2) selecting the lowest energy structure obtained in the step (1), determining an exposed crystal face to be researched, shearing a surface structure, and dividing a surface layer and a vacuum layer, wherein the thickness of the vacuum layer is more than 10 angstroms, and the number of layers of the surface layer is more than 4; performing optimization calculation to obtain an optimized surface structure;

(3) analyzing and determining possible adsorption configurations of reactant and product molecules adsorbed at adsorption sites in a vacuum environment on the basis of the optimized surface structure obtained in the step (2);

(4) selecting solvent molecules on the basis of the possible adsorption configuration obtained in the step (3), and calculating by using a density functional theory on the basis of an implicit solvent model to obtain the most stable adsorption configuration of the molecules in a solvent environment;

(5) and (4) determining the initial state and the final state of the reaction on the basis of the most stable adsorption configuration of the reactant and the product molecules in the solvent environment obtained in the step (4), so as to calculate the transition state and the reaction potential barrier of the reaction in the solvent environment and obtain the mechanism of the catalytic reaction on the surface of the catalyst in the solvent environment.

7. The method of claim 6, wherein the step (3) of analyzing the possible adsorption configuration of the reactant and product molecules at the adsorption sites in the vacuum environment comprises determining the adsorption sites based on the optimized surface structure obtained in step (2) to analyze the possible adsorption configuration of the reactant and product molecules at the adsorption sites.

8. The method of claim 6 or 7, wherein the method of calculating of step (5) comprises a transition state search method.

9. The method of claim 8, wherein the transition state search method comprises NEB or CI-NEB.

10. The calculation method according to any one of claims 1 to 9, wherein the method can be used for calculating and obtaining the adsorption structure, adsorption energy and migration energy of the catalyst surface molecules in a solvent environment;

preferably, the method can be used to predict intermediate products, reaction barriers and reaction paths of catalyst surface chemistry in a solvent environment.

Technical Field

The invention relates to the field of computing materials and computational chemistry, in particular to a computing method for a catalytic reaction mechanism on the surface of a catalyst in a simulated solvent environment.

Background

Catalysts are of great importance throughout the modern chemical industry, with almost 80% or more of the chemicals being made using catalysts in the manufacturing process. The search for and improvement of new, highly efficient catalysts is one of the very important tasks in modern chemical research. However, the research on the catalyst is not thorough, and the intrinsic catalytic reaction mechanism needs to be studied more deeply. The main process of catalytic reaction takes place on the surface of catalyst, so it is very important to monitor the absorption and desorption of the reactant and product on the surface of catalyst and the catalytic reaction process, but with the current experimental observation means, there are many difficulties in situ observation of the microscopic process of catalytic reaction on the atom and molecular level, and it can't meet the demand of rapid development in the catalytic field. The catalytic reaction process of the surface of the catalyst is simulated by combining the first principle calculation method with the existing physical and chemical rules, so that the defects of in-situ characterization means can be effectively supplemented, the process of the surface catalytic reaction is understood and even predicted from the microscopic view of atomic molecules, and the catalyst is further designed or improved. At present, the simulation of catalytic reaction on the surface of a catalyst by utilizing a first sexual principle is a research hotspot at home and abroad.

Through the calculation of a first principle, researchers have carried out some work on the aspects of band gap regulation and prediction of band edge positions of materials, adsorption, desorption and migration of specific crystal faces of catalysts, prediction of chemical reaction paths of catalytic reactions on surface and the like. However, most of the theoretical calculation work related to the photocatalyst only considers the vacuum environment or the gas-solid interface, and the actual photocatalytic reaction is mostly carried out in the solvent environment (particularly the water environment). Many influencing factors brought by the solvent environment are ignored in the conclusion obtained by calculation under the gas-solid model, and the factors are often of great importance. Such as: calculating the position of a valence conduction band of a certain catalyst under a gas-solid model, and under the solvent environment, if the energy level position is suitable due to energy band bending caused by a solid-liquid interface, reevaluating; the reaction path from the surface reactant of the catalyst to the reduction product is complex, the number of intermediate products is large, and the predicted possible reaction path is calculated under a gas-solid model and can be greatly changed under the solvent environment. Therefore, the simulation of the first principle under the solid-liquid interface is extremely important.

CN108256286A discloses a reaction mechanism research and analysis method for oxidizing benzyl alcohol into benzaldehyde by oxygen in an amphoteric water-soluble catalyst, which adopts a density functional theory to carry out amphoteric water-soluble Cu^IIThe reaction mechanism of the TEMPO catalytic system for catalyzing and oxidizing alcohol into aldehyde in the alkaline aqueous solution is researched; CN106430092A discloses graphiteSimulation method for water decomposition performance of alkene-loaded semiconductor material, which simulates surface catalytic reduction H of composite material by optimizing structure of composite material₂O to H₂The relation between the structure of the defect-state graphene-loaded semiconductor catalyst CdS composite material and the performance of hydrogen production by decomposing water is researched by adopting a density functional theory of a first raw material and a molecular dynamics simulation method; the above documents all adopt density functional theory to calculate and research the mechanism of catalytic reaction, but the analysis process only adopts vacuum simulation conditions, so that the simulation result is greatly different from the actual result.

Although the above documents provide a method for simulating and calculating a catalytic reaction mechanism, the analysis process thereof adopts a vacuum environment, so that the accuracy of the result is poor, and in order to further improve the precision of the catalytic mechanism simulation calculation, it is still of great significance to develop a calculation method suitable for simulating a catalytic reaction mechanism on the surface of a catalyst in a solvent environment.

Disclosure of Invention

The invention aims to provide a method for calculating a catalytic reaction mechanism on the surface of a catalyst under a simulated solvent environment, which comprises the steps of dividing a surface system model of the catalyst into a crystal periodic structure, a surface layer and a vacuum layer, and calculating by using a density functional theory based on an implicit solvent model to obtain the catalytic reaction mechanism on the surface of the catalyst under the solvent environment; compared with the traditional calculation method under the vacuum environment, the method has the advantages that the calculation result is more accurate, the microscopic mechanism of catalytic reaction can be deeply understood by using the method, and theoretical support is provided for experimental improvement and novel catalyst design.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for calculating a catalytic reaction mechanism on the surface of a catalyst in a simulated solvent environment, which comprises the steps of dividing a surface system model of the catalyst into a crystal periodic structure, a surface layer and a vacuum layer, and calculating by using a density functional theory based on an implicit solvent model to obtain the catalytic reaction mechanism on the surface of the catalyst in the solvent environment.

The method is based on an implicit solvent model and utilizes a density functional theory to calculate and obtain a catalytic reaction mechanism of the catalyst surface in a solvent environment, compared with a traditional calculation method in a vacuum environment, the calculated catalytic reaction mechanism of the catalyst surface is more accurate, the method adopts the implicit solvent model, the calculation scale is smaller, a model which is described by thousands of atoms under an explicit solvent model is needed, and the method can be accurately described by 18-220 atoms.

The method adopts an implicit solvent model to solve the problems that solvent influence is neglected and the error of a calculation result is large in the calculation process of the surface reaction mechanism of the catalyst in the traditional vacuum environment.

Preferably, the method for calculating the catalytic reaction mechanism on the surface of the catalyst in the solvent environment based on the implicit solvent model by using the density functional theory comprises the step of calculating the most stable adsorption configuration of reactant and product molecules on the surface of the catalyst in the solvent environment by using the density functional theory, so that the catalytic reaction mechanism on the surface of the catalyst in the solvent environment is obtained.

Preferably, the method for calculating the most stable adsorption configuration of the reactant and the product molecules on the surface of the catalyst in the solvent environment by using the density functional theory comprises the steps of calculating the possible adsorption configurations of the reactant and the product molecules on the adsorption sites on the surface of the catalyst in the vacuum environment by using the density functional theory, and then calculating the most stable adsorption configuration of the reactant and the product molecules on the adsorption sites on the surface of the catalyst in the solvent environment by using the density functional theory in combination with an implicit solvent model.

The method adopts the possible adsorption configuration of the reactant and the product molecules adsorbed on the adsorption sites on the surface of the catalyst in the vacuum environment and combines an implicit solvent model to calculate the most stable adsorption configuration and reaction path of the reactant and the product molecules on the surface of the catalyst in the solvent environment, and the calculation method is simpler and more convenient and is beneficial to shortening the calculation scale.

Preferably, the catalyst comprises a metallic catalytic material and a semiconductor catalytic material.

Preferably, the metal catalytic material comprises any one of Au, Pt, Ag, Cu or Ni or a combination of at least two thereof, which illustratively includes a combination of Au and Pt, a combination of Ag and Cu, or a combination of Ni and Pt, and the like.

Preferably, the semiconductor catalytic material comprises any one of a binary oxide, a ternary oxide or a sulfide, or a combination of at least two thereof.

Preferably, the semiconductor catalytic material comprises BiOCl.

Preferably, the vacuum layer has a thickness > 10 angstroms, such as 12 angstroms, 15 angstroms, 18 angstroms, or 20 angstroms, etc.

Preferably, the number of layers of the surface layer is > 4 layers, such as 5, 8, 10, 12 or 14 layers, etc.

Preferably, the surface ensures that the length of the super cell in the x-direction and y-direction is > 10 angstrom, such as 12 angstrom, 15 angstrom, 18 angstrom or 20 angstrom, respectively, by structuring the super cell.

Preferably, the implicit solvent model comprises any one of Onsager, PCM, CPCM, IPCM, SCIPCM, COSMO, SMD, or SMx.

Preferably, the solvent comprises any one of water, ethanol, acetone, acetonitrile or benzene or a combination of at least two of them, the combination comprises a combination of water and ethanol, a combination of acetone and acetonitrile or a combination of benzene and ethanol, etc.

Preferably, the method further comprises determining the investigated exposed crystal planes before the partitioning of the catalyst surface system model.

Preferably, the exposed crystal plane includes any one of (001), (101), (110), or (111) or a combination of at least two thereof.

Preferably, the method for calculating by using the density functional theory comprises generalized gradient approximation and/or local density approximation.

Preferably, the functional form of the generalized gradient approximation includes any one of PW91, PBE or BLYP.

Preferably, the software for local density approximation comprises VASP, Dmol³Either Gaussian or Q-Chem.

As a preferable technical scheme of the invention, the method for calculating the catalytic reaction mechanism of the catalyst surface under the simulated solvent environment comprises the following steps:

(1) determining crystal structure information of the catalyst, and then carrying out geometric structure optimization to obtain the lowest energy structure of the bulk material of the catalyst;

(2) selecting the lowest energy structure obtained in the step (1), determining an exposed crystal face to be researched, shearing a surface structure, and dividing a surface layer and a vacuum layer, wherein the thickness of the vacuum layer is more than 10 angstroms, and the number of layers of the surface layer is more than 4; performing optimization calculation to obtain an optimized surface structure;

(3) analyzing and determining possible adsorption configurations of reactant and product molecules adsorbed at adsorption sites in a vacuum environment on the basis of the optimized surface structure obtained in the step (2);

(4) selecting solvent molecules on the basis of the possible adsorption configuration obtained in the step (3), and calculating by using a density functional theory on the basis of an implicit solvent model to obtain the most stable adsorption configuration of the molecules in a solvent environment;

(5) and (4) determining the initial state and the final state of the reaction on the basis of the most stable adsorption configuration of the reactant and the product molecules in the solvent environment obtained in the step (4), so as to calculate the transition state and the reaction potential barrier of the reaction in the solvent environment and obtain the mechanism of the catalytic reaction on the surface of the catalyst in the solvent environment.

Preferably, the method for determining the crystal structure information of the catalyst in the step (1) comprises deriving a crystal structure file of the catalyst from a crystallography database.

Preferably, the crystallography database comprises ICSD.

Preferably, the calculation method for geometry optimization in step (1) includes any one of exchange correlation potential, exchange correlation functional, convergence accuracy or K-point density.

Preferably, in the process of geometric structure optimization in the step (1), the optimized crystal structure parameters are compared with experimental parameters, the accuracy of the optimized crystal structure parameters is verified, then geometric structure optimization is repeatedly performed, and finally the standard basically compounded with the experimental parameters is achieved, so that the lowest energy structure of the bulk material of the catalyst is obtained.

Preferably, the direction of shearing the surface structure in step (2) is a vertical direction.

Preferably, the process of shearing the surface structure in the step (2) further comprises constructing different surface atom termination structure models according to the bond breaking condition and the difference of atom positions.

Preferably, the method for optimizing calculation in step (2) includes any one of exchange correlation potential, exchange correlation functional, convergence accuracy or K-point density.

Preferably, the method for analyzing and determining the possible adsorption configuration of the reactant and product molecules on the adsorption sites in the vacuum environment in step (3) comprises determining the adsorption sites on the basis of the optimized surface structure obtained in step (2), and then analyzing the possible adsorption configuration of the reactant and product molecules on the adsorption sites.

Preferably, the optimized surface structure obtained in step (2) is expanded in both directions X, Y before the adsorption sites are determined to avoid that the adsorbed molecules are too close together due to the periodic structure.

Preferably, the method of calculating in step (5) includes a transition state search method.

Preferably, the transition state search method comprises NEB or CI-NEB.

Preferably, the method for calculating the catalytic reaction mechanism on the surface of the catalyst in the simulated solvent environment can be used for calculating and obtaining the adsorption structure, the adsorption energy and the migration energy of the molecules on the surface of the catalyst in the solvent environment.

Preferably, the calculation method for simulating the catalytic reaction mechanism of the catalyst surface in the solvent environment can be used for predicting intermediate products, reaction barriers and reaction paths of the catalytic surface chemical reaction in the solvent environment.

Preferably, the calculation method for simulating the catalytic reaction mechanism of the catalyst surface in the solvent environment is used for calculating the reaction mechanism of the catalyst surface in the photocatalytic reaction process in the solvent environment.

Preferably, the method for calculating the catalytic reaction mechanism of the catalyst surface in the simulated solvent environment is used for calculating BiOCl as the catalyst, and CO is subjected to photocatalytic reduction in the solvent environment₂The catalyst surface catalyzes the reaction mechanism in the process of (1).

Compared with the prior art, the invention has the following beneficial effects:

(1) the method for calculating the catalytic reaction mechanism on the surface of the catalyst in the simulated solvent environment adopts the implicit solvent model combined with the calculation method of the density functional theory, so that the accuracy of the result obtained by calculation is obviously improved compared with the traditional calculation method in the vacuum environment;

(2) the method for calculating the catalytic reaction mechanism on the surface of the catalyst in the simulated solvent environment gives consideration to the precision and the calculated amount of the solvent environment, the calculation scale is small, and the accuracy of the calculation result is high.

Drawings

FIG. 1 is a diagram showing the lowest energy structure of a bulk material of a catalyst obtained in step (1) in example 1 of the present invention;

FIG. 2 is a diagram showing the structure of the surface of the catalyst obtained in step (2) in example 1 of the present invention after the optimization;

FIGS. 3A-3E are CO in vacuum₂、CO、CH₃OH、CH₄And the most stable adsorption pattern of COOH on the surface of BiOCl;

FIGS. 4A-4E are CO in aqueous environments₂、CH₃OH、CH₄Most stable adsorption pattern of CO and COOH on the surface of BiOCl;

FIG. 5 shows the CO concentration in the vacuum environment in example 1 of the present invention₂A sub-wave state density graph adsorbed on the BiOCl surface;

FIG. 6 shows CO in water environment in example 1 of the present invention₂A sub-wave state density graph adsorbed on the BiOCl surface;

FIGS. 7A to 7C are each a diagram showing CO in a solvent atmosphere in example 1 of the present invention₂Schematic representation of reactants, products and intermediates decomposed on the surface of BiOCl.

FIG. 8 is a path diagram of a transition state search.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.