Construction method of stable distribution structure of oxygen-containing functional groups on surface of graphene oxide

Abstract

The invention discloses a method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide, the stable distribution structure of the oxygen-containing functional groups on the surface of the graphene oxide can be constructed through density functional theory calculation on the basis of the microcosmic local distribution thermodynamic law of the oxygen-containing functional groups on the surface of the graphene oxide, the construction process is simple and efficient, and the method is suitable for industrial production. The dependence on computing resources is not high, and a scientific and reasonable theoretical structure model can be provided for related theoretical calculation research of the graphene oxide.

Description

Technical Field

[0001] The present invention relates to the technical field of computational material chemistry, and in particular to a method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide. Background Art

[0002] Graphene oxide is an important derivative of graphene and can serve as a reliable precursor for the large-scale preparation of high-performance graphene macro-assembly materials. The chemical structure of graphene oxide is extremely complex. The types and relative contents of oxygen-containing functional groups on its surface are mainly affected by the preparation process and the degree of oxidation, and there is no fixed stoichiometric ratio. Over the past few decades, the continuous development of experimental characterization methods has promoted the establishment of a series of graphene oxide chemical structure models. Among them, the most widely used Lerf-Klinowski model believes that the surface of graphene oxide has randomly distributed oxidized and unoxidized regions. The randomly distributed hydroxyl groups and epoxy groups in the oxidized regions are very close, while the edges are mainly hydroxyl and carboxyl groups. There is a strong correlation between the surface chemical structure of graphene oxide and its physicochemical properties, but experimental characterization methods have limited ability to explore the fine chemical structure of graphene oxide, making it difficult to reveal the structure-activity relationship of graphene oxide at the microscopic level.

[0003] Theoretical calculation studies represented by density functional theory calculations and molecular dynamics simulations can explore the structure and properties of materials at the microscopic level of the atomic scale, laying a theoretical foundation for revealing the structure-activity relationship of graphene oxide. At the beginning of theoretical calculation studies, it is necessary to first construct a scientific and reasonable general model of the fine chemical structure of graphene oxide, which relies on the researchers' theoretical understanding of the distribution of oxygen-containing functional groups on the surface of graphene oxide. With the help of theoretical calculation studies, the thermodynamic distribution law of oxygen-containing functional groups on the surface of graphene oxide is revealed. In the local microstructure at the atomic scale, the distribution of oxygen-containing functional groups is mainly affected by the joint effects of electron distribution, steric hindrance and hydrogen bonding. However, in existing studies, the oxygen-containing functional groups in common graphene oxide structural models are randomly distributed or periodically distributed, which lacks a theoretical basis and may lead to unreasonable structures, greatly affecting the scientific nature and reliability of subsequent theoretical calculation research results.

[0004] How to simply and efficiently construct a scientifically sound and stable distribution of oxygen-containing functional groups on the surface of graphene oxide for subsequent theoretical calculations has long been a key focus in theoretical research related to graphene oxide structure and properties. To address this issue, we propose a solution. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide, so as to solve the structural irrationality caused by the random distribution or periodic regular distribution of oxygen-containing functional groups on the surface of the commonly used graphene oxide structure model, and provide a reliable structural model for theoretical calculation research involving the structure and performance of graphene oxide.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide, wherein the oxygen-containing functional groups on the surface of graphene oxide are hydroxyl groups and epoxy groups, comprising the following steps:

[0008] S1: Use modeling software to construct a single-layer graphene structure model G, setting The vacuum layer above;

[0009] S2: constructing an initial stable structure on the surface of the single-layer graphene structure model G, adding a number of initial oxygen-containing functional groups, which bond with carbon atoms to form a graphene oxide structure model GO-1;

[0010] S3: Based on density functional theory, using the first-principles calculation software CP2K, the generalized gradient approximation was adopted, the DFT-D3 (BJ) dispersion-corrected PBE exchange-correlation functional was set, and the DZVP-MOLOPT-SR-GTH basis set was combined to perform geometry optimization on the graphene oxide structure model GO-1, and the optimized graphene oxide structure model GO-1' structure was obtained;

[0011] S4: Based on density functional theory, using CP2K and the REPEAT method, the RESP charge was calculated to analyze the changes in the electron distribution of carbon atoms caused by the bonding between the surface of the graphene oxide structure model GO-1' and the oxygen-containing functional groups;

[0012] S5: Select a number of carbon atoms on the surface of the graphene oxide structural model GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add new oxygen-containing functional groups to form bonds with them, and obtain the structural model GO-2;

[0013] S6: Repeat steps S3-S5, and continuously add oxygen-containing functional groups according to the change in the electron distribution on the graphene oxide surface until the number and ratio of oxygen-containing functional groups in the graphene oxide structure reach the desired level, thereby obtaining a stable distribution structure of oxygen-containing functional groups on the graphene oxide surface.

[0014] Preferably, in step S5, the newly added oxygen-containing functional groups and the existing oxygen-containing functional groups are located on both sides of the graphene carbon plane to avoid steric hindrance.

[0015] Preferably, in step S5, the hydroxyl group in the oxygen-containing functional group is bonded to only one carbon atom, and the carbon atom with more electrons is selected to form a bond with it; the epoxy group is bonded to two carbon atoms, and two adjacent carbon atoms that have gained electrons are selected to form a bond with it; if there are no two adjacent carbon atoms that have gained electrons, the two carbon atoms whose sum of the number of electrons gained and lost is positive and as large as possible are selected to form a bond with the epoxy group.

[0016] Preferably, in step S5, after the new oxygen-containing functional group is added, the orientation of the hydroxyl group is adjusted so that the hydroxyl group forms as many hydrogen bonds as possible with adjacent oxygen-containing functional groups.

[0017] Preferably, step S6 is performed by repeatedly looping through the following steps: geometrically optimizing the structure; analyzing changes in surface electron distribution; and adding oxygen-containing functional groups at selected sites. Repeating these loops, oxygen-containing functional groups are continuously added until the desired number and ratio of oxygen-containing functional groups in the graphene oxide structure are achieved, thereby achieving a stable distribution of oxygen-containing functional groups on the graphene oxide surface.

[0018] The beneficial effects of the present invention are:

[0019] 1. Based on the thermodynamic laws of the microscopic local distribution of oxygen-containing functional groups on the surface of graphene oxide, density functional theory calculations are used to construct a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide, providing a scientific and reasonable theoretical structural model for subsequent theoretical calculation studies on the structure and properties of graphene oxide;

[0020] 2. The process of constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide is simple and efficient, with low dependence on computing resources. It is possible to independently design a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide with different types and numbers of oxygen-containing functional groups based on different research. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Figure 1 is a diagram of the addition process and structure of oxygen-containing functional groups on the graphene oxide surface corresponding to Example 1, wherein the dotted circles represent the subsequent hydroxyl binding sites selected based on the surface electron distribution;

[0022] Figure 2 The graphene oxide surface oxygen-containing functional group addition process and structure corresponding to Example 2, wherein the dotted circle represents the subsequent hydroxyl group binding site selected based on the surface electron distribution, and the dotted box represents the subsequent epoxy group binding site selected based on the surface electron distribution;

[0023] Figure 3 3 is a diagram of the addition process and structure of oxygen-containing functional groups on the graphene oxide surface corresponding to Example 3, wherein the dotted circle represents the subsequent hydroxyl binding site selected based on the surface electron distribution, and the dotted box represents the subsequent epoxy binding site selected based on the surface electron distribution. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following is only a preferred embodiment of the present invention, and the scope of protection is not limited to this embodiment. All technical solutions under the concept of the present invention should fall within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figure 1 As shown,

[0027] S1: Building with Materials Studio The single-layer graphene structure model G, containing 168 carbon atoms, is set Vacuum layer;

[0028] S2: Construct an initial stable structure on the G surface, add two hydroxyl groups, bond with carbon atoms, and form a graphene oxide structure model GO-1;

[0029] S3: Based on density functional theory, using the first-principles calculation software CP2K, the generalized gradient approximation was adopted, the DFT-D3 (BJ) dispersion-corrected PBE exchange-correlation functional was set, and the DZVP-MOLOPT-SR-GTH basis set was combined to perform geometry optimization on GO-1 and obtain the optimized GO-1' structure;

[0030] S4: Based on density functional theory, using CP2K and the REPEAT method, the RESP charge was calculated to analyze the changes in the electron distribution of carbon atoms caused by the bonding of the two hydroxyl groups on the GO-1' surface.

[0031] S5: Select four carbon atoms on the surface of GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add four new hydroxyl groups to form bonds with them, and obtain the structural model GO-2;

[0032] S6: Repeat the cycle of S3-S5, and according to the change of the electron distribution on the graphene oxide surface, 4, 4, 4, 4, 6, 8, 8, 12, 7, and 7 hydroxyl groups are added in sequence on the basis of the initial stable structure of 2 hydroxyl groups, and finally a stable distribution structure of oxygen-containing functional groups on the graphene oxide surface (C 168 OH 66 ).

[0033] Example 2

[0034] like Figure 2 As shown,

[0035] S1: Building with Materials Studio The single-layer graphene structure model G, containing 168 carbon atoms, is set Vacuum layer;

[0036] S2: Construct an initial stable structure on the G surface, add two hydroxyl groups, bond with carbon atoms, and form a graphene oxide structure model GO-1;

[0037] S3: Based on density functional theory, using the first-principles calculation software CP2K, the generalized gradient approximation was adopted, the DFT-D3 (BJ) dispersion-corrected PBE exchange-correlation functional was set, and the DZVP-MOLOPT-SR-GTH basis set was combined to perform geometry optimization on GO-1 and obtain the optimized GO-1' structure;

[0038] S4: Based on density functional theory, using CP2K and the REPEAT method, the RESP charge was calculated to analyze the changes in the electron distribution of carbon atoms caused by the bonding of the two hydroxyl groups on the GO-1' surface.

[0039] S5: Select two adjacent carbon atoms on the surface of GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add an epoxy group to form a bond with them, and obtain the structural model GO-2;

[0040] S6: Repeat the cycle of S3-S5. According to the change of the electron distribution on the graphene oxide surface, 1 epoxy group, 2 hydroxyl groups and 1 epoxy group, 4 hydroxyl groups and 2 epoxy groups, 6 hydroxyl groups and 3 epoxy groups, 10 hydroxyl groups and 4 epoxy groups, and 10 hydroxyl groups and 6 epoxy groups are added in sequence on the basis of the initial stable structure of 2 hydroxyl groups, and finally a stable distribution structure of oxygen-containing functional groups on the graphene oxide surface (C 168 OH 34 O 17 ),like Figure 2 shown.

[0041] Example 3

[0042] like Figure 3 As shown,

[0043] S1: Building with Materials Studio The single-layer graphene structure model G, containing 168 carbon atoms, is set Vacuum layer;

[0044] S2: Construct an initial stable structure on the G surface, add two hydroxyl groups and two epoxy groups, bond with carbon atoms, and form a graphene oxide structure model GO-1;

[0045] S3: Based on density functional theory, using the first-principles calculation software CP2K, the generalized gradient approximation was adopted, the DFT-D3 (BJ) dispersion-corrected PBE exchange-correlation functional was set, and the DZVP-MOLOPT-SR-GTH basis set was combined to perform geometry optimization on GO-1 and obtain the optimized GO-1' structure;

[0046] S4: Based on density functional theory, using CP2K and the REPEAT method, the RESP charge was calculated, and the changes in the electron distribution of carbon atoms caused by the bonding of GO-1' surface with two hydroxyl groups and two epoxy groups were analyzed;

[0047] S5: Select four carbon atoms on the surface of GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add four hydroxyl groups to form bonds with them, select four adjacent carbon atoms on the surface of GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add two epoxy groups to form bonds with them, and obtain the structural model GO-2;

[0048] S6: Repeat the cycle of S3-S5. According to the change of the electron distribution on the graphene oxide surface, 4 hydroxyl-2 epoxy groups, 8 hydroxyl-3 epoxy groups, 10 hydroxyl-5 epoxy groups, and 12 hydroxyl-9 epoxy groups are added in sequence on the basis of the initial stable structure of 2 hydroxyl groups and 2 epoxy groups, and finally a stable distribution structure of oxygen-containing functional groups on the graphene oxide surface (C 168 OH 36 O 21 ),like Figure 3 shown.

[0049] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide, wherein the oxygen-containing functional groups on the surface of graphene oxide are hydroxyl groups and epoxy groups, characterized in that: The following steps are involved: S1: Use modeling software to construct a single-layer graphene structure model G, setting The vacuum layer above; S2: constructing an initial stable structure on the surface of the single-layer graphene structure model G, adding a number of initial oxygen-containing functional groups, which bond with carbon atoms to form a graphene oxide structure model GO-1; S3: Based on density functional theory, using the first-principles calculation software CP2K, the generalized gradient approximation was adopted, the DFT-D3 (BJ) dispersion-corrected PBE exchange-correlation functional was set, and the DZVP-MOLOPT-SR-GTH basis set was combined to perform geometry optimization on the graphene oxide structure model GO-1, and the optimized graphene oxide structure model GO-1' structure was obtained; S4: Based on density functional theory, using CP2K and the REPEAT method, the RESP charge was calculated to analyze the changes in the electron distribution of carbon atoms caused by the bonding between the surface of the graphene oxide structure model GO-1' and the oxygen-containing functional groups; S5: Select a number of carbon atoms on the surface of the graphene oxide structural model GO-1' that have relatively more electrons and have not yet formed bonds with oxygen-containing functional groups, add new oxygen-containing functional groups to form bonds with them, and obtain the structural model GO-2; S6: Repeat steps S3-S5, and continuously add oxygen-containing functional groups according to the change in the electron distribution on the graphene oxide surface until the number and ratio of oxygen-containing functional groups in the graphene oxide structure reach the desired level, thereby obtaining a stable distribution structure of oxygen-containing functional groups on the graphene oxide surface.

2. The method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide according to claim 1, wherein: In step S5, the newly added oxygen-containing functional groups and the existing oxygen-containing functional groups are located on both sides of the graphene carbon plane to avoid steric hindrance.

3. The method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide according to claim 2, wherein: In step S5, the hydroxyl group in the oxygen-containing functional group is bonded to only one carbon atom, and the carbon atom with more electrons is selected to form a bond with it; the epoxy group is bonded to two carbon atoms, and two adjacent carbon atoms that have gained electrons are selected to form a bond with it; if there are no two adjacent carbon atoms that have gained electrons, the two carbon atoms whose sum of the number of electrons gained and lost is positive and as large as possible are selected to form a bond with the epoxy group.

4. The method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide according to claim 3, wherein: In step S5, after the new oxygen-containing functional group is added, the orientation of the hydroxyl group is adjusted so that the hydroxyl group forms as many hydrogen bonds as possible with the adjacent oxygen-containing functional groups.

5. The method for constructing a stable distribution structure of oxygen-containing functional groups on the surface of graphene oxide according to claim 1, wherein: In step S6, the following steps are repeatedly performed: geometric optimization of the structure; analysis of changes in surface electron distribution; and addition of oxygen-containing functional groups at selected sites. This process is repeated repeatedly until the desired number and ratio of oxygen-containing functional groups in the graphene oxide structure are achieved, resulting in a stable distribution of oxygen-containing functional groups on the graphene oxide surface.

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