阅读说明：本技术 一种测试二氧化钛复合材料光催化效果的方法 (Method for testing photocatalytic effect of titanium dioxide composite material ) 是由 刘婷 王巍 李铸铁 谢景洋 张晓辰 于 2019-09-09 设计创作，主要内容包括：本发明涉及光催化测试分析技术领域,尤其涉及一种测试二氧化钛复合材料光催化效果的方法。是基于密度泛函理论计算材料的禁带宽度值、探针分子的吸附能量值参数；依据上述参数定性判断材料的光催化等级的方法。本发明可实现多种二氧化钛复合材料光催化效果的快速评价,有助于节约实验时间、减少实验成本,进而预测新型二氧化钛复合材料的光催化效果,从而推进光催化材料的研究与应用。(The invention relates to the technical field of photocatalytic test analysis, in particular to a method for testing the photocatalytic effect of a titanium dioxide composite material. Calculating parameters of forbidden band width value of the material and adsorption energy value of probe molecules based on a density functional theory; and (3) qualitatively judging the photocatalytic grade of the material according to the parameters. The method can realize the rapid evaluation of the photocatalytic effect of various titanium dioxide composite materials, is beneficial to saving the experimental time and reducing the experimental cost, and further predicts the photocatalytic effect of the novel titanium dioxide composite material, thereby promoting the research and application of the photocatalytic material.)

1. A method for testing the photocatalytic effect of a titanium dioxide composite material is characterized by comprising the following steps: the qualitative assessment method comprises the following steps: calculating parameters of forbidden band width value of the material and adsorption energy value of probe molecules based on a density functional theory; and qualitatively judging the photocatalytic grade of the material according to the parameters.

2. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 1, characterized in that: before calculating the parameters, establishing a simulation model of the active surface of the titanium dioxide composite material and the probe molecules.

3. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 2, characterized in that: the active surface of the titanium dioxide composite material is rutile type TiO₂Anatase type TiO₂The surface is the active surface of a carrier, the unit cell structure size of the active surface of the titanium dioxide composite material is 2 x 2 or 4 x 2, and the probe molecule is a formaldehyde, acetaldehyde or nitrogen oxide small molecule pollutant.

4. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 1, characterized in that: the calculated value of forbidden band width E of the material_gThe calculation formula of (2) is as follows:

E_g＝E_CB-E_VB

Wherein E is_CBThe energy value of the composite surface low-energy band top is obtained; e_VBThe energy value of the composite surface high-energy conduction band bottom is obtained; adsorption energy value E of the probe molecule_adsorpThe calculation formula of (2) is as follows:

E_adsorp＝E_total-E_surface-E_{probemolecule}

Wherein E is_totalis the total energy of the composite system; e_surfaceThe total energy of the composite surface; e_{probemolecule}Is the energy of the probe molecule.

5. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 4, characterized in that:

In order to verify the reliability of the calculation method, the calculated value is compared with the experimental test value by adopting an alpha factor:

α＝E′_g/E_g

wherein the alpha factor is the interaction of the composite surfacecorrection coefficient, E'_gis an experimental value of the forbidden band width of the material, E_gCalculating the forbidden band width of the material; if the value range of alpha is between 1.0 and 1.2, the calculated value is proved to be applicable to quantitative evaluation of the photocatalytic performance of the titanium dioxide composite material.

6. the method for testing photocatalytic effect of titanium dioxide composite material according to claim 1, characterized in that: and dividing the photoresponse range according to the forbidden band width value of the material, and qualitatively judging the photocatalytic grade of the material according to the adsorption energy value of the probe molecules.

7. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 6, characterized in that: dividing a light response range according to the size of a forbidden band width value of the material, wherein the smaller the Eg value is, the wider the light absorption range is, the boundary of wavelengths of ultraviolet light and visible light is 400nm, namely the forbidden band width value of the material is 3.1eV, and the Eg value is less than 3.1eV, the response range of the material in a visible light region is divided; when the Eg value is more than 3.1eV, dividing the material into the response range of an ultraviolet region; then, qualitatively judging the photocatalytic grade of the material according to the adsorption energy value of the probe molecules, wherein the photocatalytic grade is divided into A class and B class, the higher the adsorption energy value is, the higher the photocatalytic reaction activity is, and the adsorption energy value E is_adsorpThe photocatalytic grade is judged as A class when the molecular weight is more than 1.0eV, and the adsorption energy value E_adsorpAnd the photocatalytic grade is judged as B class when the concentration is less than 1.0 eV.

8. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 1 or 2, characterized in that: the quantitative evaluation method comprises the following steps: after qualitative evaluation, preparing a titanium dioxide composite material sample, carrying out photocatalytic degradation reaction, and recording the concentration of probe molecules before and after the reaction by an ultraviolet spectrometer; and solving the photocatalytic removal rate of the titanium dioxide composite material.

9. the method for testing photocatalytic effect of titanium dioxide composite material according to claim 8, characterized in that: the preparation of the titanium dioxide composite material sample comprises three steps of sample preparation, pretreatment and loading; placing the sample in a photocatalytic reactor, setting the reaction conditions of the photocatalytic reactor, and carrying out photocatalytic degradation reaction; wherein the reaction conditions comprise the settings of temperature, humidity, illumination wavelength, illumination intensity, probe molecule concentration and gas flow.

10. The method for testing photocatalytic effect of titanium dioxide composite material according to claim 8, characterized in that: the calculation formula of the photocatalytic removal rate P is as follows:

Wherein, C_Ais the concentration of probe molecules before reaction; c_BThe concentration of the probe molecule after the reaction is stabilized.

Technical Field

The invention relates to the technical field of photocatalytic test analysis, in particular to a method for testing the photocatalytic effect of a titanium dioxide composite material.

Background

Due to the fact thatExcellent photocatalytic performance and chemical stability, titanium dioxide (TiO)₂) Has become the most widely used photocatalytic material in research for removing organic pollutants. In order to overcome the problems of low photocatalytic efficiency, easy poisoning and inactivation of materials, secondary pollution of materials and the like, the composite TiO is used₂Photocatalytic materials have been studied in large quantities. The titanium dioxide material is used as a base to construct a compound with materials such as carbon materials, polymers or semiconductors, and the like, and the method is an effective way for enhancing the light absorption performance of the titanium dioxide. The two or more materials have matched energy levels, can effectively separate electrons and holes, are beneficial to the transfer of the electrons, and effectively inhibit the recombination of the electrons and the holes, so that the composite material has better photocatalytic performance.

The research on the photocatalytic effect is mostly an experimental test method established on a macroscopic scale, and can realize the evaluation on the photocatalytic performance of the titanium dioxide composite material, but from the preparation of the material to the completion of the test, the research period is long, the cost is high, and the prediction on the photocatalytic performance of the material and the design improvement on a new material cannot be realized. Quantum chemistry uses quantum mechanics as a principle to study electron shell structures, chemical bond theories, intermolecular forces, chemical reaction theories, various spectra, wave spectrums and electronic energy spectrums of atoms, molecules and crystals. Particularly, with the improvement of computer performance and the acceleration of computing speed, the establishment and development of the density functional theory lead quantum chemistry to be developed in a breakthrough way and become a general tool for researching the microstructure of a substance. From a small molecular compound to a solid and then to the surface of the solid, the quantum chemistry of substances with different sizes, dimensions and dimensions based on the density functional theory can be used for very accurate calculation of relevant properties, reasonable design, physical property prediction, action mechanism research and the like of molecules and materials, and a bridge is built between the macroscopic characteristics and the microscopic characteristics of the materials. The method can lay a foundation for building a novel titanium dioxide composite material model and quickly screening a high-performance catalytic material, and provides a scientific basis for the optimization design and the industrial development of the photocatalytic composite material.

Disclosure of Invention

The technical problem to be solved by the invention is composite TiO₂Photo catalysisThe research of the photocatalytic effect of the chemical material is mostly an experimental test method established on a macroscopic scale, and the evaluation of the photocatalytic performance can be realized, but from the preparation of the material to the completion of the test, the research period is long, the cost is high, and the prediction of the photocatalytic performance of the material and the design improvement of a new material cannot be realized.

In order to solve the problems, the invention provides a computer-aided method for testing the photocatalytic effect of a titanium dioxide composite material, which can realize the rapid evaluation and the targeted measurement of the catalytic effect of the titanium dioxide composite photocatalytic material and provide a feasible scheme for accelerating the development of a novel titanium dioxide composite photocatalytic material and realizing the rapid evaluation of the photocatalytic effect of various titanium dioxide composite materials.

In order to achieve the purpose, the invention is realized by the following technical scheme: a method for testing the photocatalytic effect of a titanium dioxide composite material, wherein the qualitative evaluation method comprises the following steps: calculating parameters of forbidden band width value of the material and adsorption energy value of probe molecules based on a density functional theory; and qualitatively judging the photocatalytic grade of the material according to the parameters.

furthermore, before calculating parameters, a simulation model of the active surface of the titanium dioxide composite material and probe molecules is established.

Furthermore, the active surface of the titanium dioxide composite material is rutile type TiO₂(110) Anatase type TiO₂(101) The surface is the active surface of a carrier, the unit cell structure size of the active surface of the titanium dioxide composite material is 2 x 2 or 4 x 2, and the probe molecule is a formaldehyde, acetaldehyde or nitrogen oxide small molecule pollutant.

Further, the forbidden band width of the material is calculated as E_gThe calculation formula of (2) is as follows:

E_g＝E_CB-E_VB

Wherein E is_CBThe energy value of the composite surface low-energy band top is obtained; e_VBThe energy value of the composite surface high-energy conduction band bottom.

E_CB、E_VBThe calculation is carried out through a CAStep module of a materials studio software package;

In order to verify the reliability of the calculation method, the calculated value is compared with the experimental test value by adopting the alpha factor. And the value range of alpha is 1.0-1.2, so that the calculated value can be used for quantitatively evaluating the photocatalytic performance of the titanium dioxide composite material.

α＝E′_g/E_g

Wherein the alpha factor is an interaction correction coefficient, E ', of the composite surface'_gIs an experimental value of the forbidden band width of the material, E_gThe calculated value of the forbidden band width of the material.

Forbidden band width experimental value E'_gThe experimental test process comprises the steps of utilizing the absorbance and the wavelength of the composite material in the ultraviolet visible diffuse reflection measurement to be plotted, and adopting a line intercept method to make an absorption wavelength threshold value lambda_g(nm) and then by the formula E_g＝1240/λ_g(eV) was obtained.

Further, the adsorption energy value E of the probe molecule_adsorpThe calculation formula of (2) is as follows:

E_adsorp＝E_total-E_surface-E_{probemolecule}

Wherein E is_totalIs the total energy of the composite system; e_surfaceThe total energy of the composite surface; e_{probemolecule}Is the energy of the probe molecule. E_total、E_surface、E_{probemolecule}Is calculated by a 'materials studio software package'.

Furthermore, the optical response range is divided according to the forbidden band width value of the material, and then the photocatalytic grade of the material is qualitatively judged according to the adsorption energy value of the probe molecules.

Further, the optical response range is divided according to the forbidden bandwidth value of the material, E_gThe smaller the value, the wider the absorption range, bounded by the 400nm wavelength boundary between ultraviolet and visible light, i.e. the 3.1eV forbidden bandwidth of the material, E_gIf the value is less than 3.1eV, the material is divided into a response range of a visible light region; e_gIf the value is more than 3.1eV, dividing the material into a response range of an ultraviolet region; then, the photocatalytic grade of the material is qualitatively judged according to the adsorption energy value of the probe molecules, the photocatalytic grade is divided into A class and B class, and the adsorption energy isThe larger the adsorption energy value is, the higher the photocatalytic reaction activity is, the adsorption energy value is more than 1.0eV, the photocatalytic grade is judged as A-type, the adsorption energy value is less than 1.0eV, and the photocatalytic grade is judged as B-type.

Further, the quantitative evaluation method comprises: after qualitative evaluation, preparing a titanium dioxide composite material sample, carrying out photocatalytic degradation reaction, and recording the concentration of probe molecules before and after the reaction by an ultraviolet spectrometer; and solving the photocatalytic removal rate of the titanium dioxide composite material.

Further, the preparation of the titanium dioxide composite material sample comprises three steps of sample preparation, pretreatment and loading; placing the sample in a photocatalytic reactor, setting the reaction conditions of the photocatalytic reactor, and carrying out photocatalytic degradation reaction; wherein the reaction conditions comprise the settings of temperature, humidity, illumination wavelength, illumination intensity, probe molecule concentration and gas flow.

Further, the calculation formula of the photocatalytic removal rate P is as follows:

Wherein, C_AIs the concentration of probe molecules before reaction; c_BThe concentration of the probe molecule after the reaction is stabilized.

the invention has the beneficial effects that:

1) The method for testing the photocatalytic effect of the titanium dioxide composite material can realize the rapid evaluation of the photocatalytic effect of various titanium dioxide composite materials, combine qualitative and quantitative tests, shorten the test evaluation time and greatly reduce the preparation cost of the composite material.

2) The method for testing the photocatalytic effect of the titanium dioxide composite material combines the theoretical research and the experimental test of the photocatalytic material, adopts a theoretical guidance experiment mode, can not only explore the photocatalytic mechanism of the titanium dioxide composite material and realize the prediction of the photocatalytic performance of the novel composite material, but also can play a certain role in promoting the research and the application of the titanium dioxide photocatalytic material.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

FIG. 2 is a simulation model of the active surface G-Rutile (110) of the graphene/titanium dioxide composite material in example 1;

FIG. 3 shows formaldehyde (CH) as a probe molecule in example 1₂O) a simulation model;

fig. 4 is an ultraviolet-visible absorption spectrum of the graphene/titanium dioxide composite material in example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.