阅读说明：本技术 一种三维ZnFe2O4/BiOCl(001)复合光催化剂及其制备方法 (Three-dimensional ZnFe2O4/BiOCl (001) composite photocatalyst and preparation method thereof ) 是由 宋桂贤 罗晋朝 于 2020-06-08 设计创作，主要内容包括：本发明实施例提供了一种三维ZnFe<Sub>2</Sub>O<Sub>4</Sub>/BiOCl(001)复合光催化剂及其制备方法,首先以油胺作为形貌引导剂和晶面控制剂,运用水热法在140℃～180℃温度下水热制备三维微球结构BiOCl(001),再在BiOCl的表面沉积ZnFe<Sub>2</Sub>O<Sub>4</Sub>纳米颗粒,形成ZnFe<Sub>2</Sub>O<Sub>4</Sub>/BiOCl(001)复合物,在环己醇中光催化还原CO<Sub>2</Sub>制备有机化合物的活性测试中表现出良好的催化活性,与片状结构ZnFe<Sub>2</Sub>O<Sub>4</Sub>/BiOCl复合物相比,目标产物的生产量有较大的提高。本发明的三维ZnFe<Sub>2</Sub>O<Sub>4</Sub>/BiOCl(001)复合光催化剂具有制备过程简单,催化剂形貌和晶形可控,催化活性良好的优点。(The embodiment of the invention provides three-dimensional ZnFe 2 O 4 /BiOCl (001) composite photocatalystFirstly, oleylamine is used as a morphology guiding agent and a crystal face control agent, a hydrothermal method is used for preparing BiOCl (001) with a three-dimensional microsphere structure at the temperature of 140-180 ℃, and ZnFe is deposited on the surface of the BiOCl 2 O 4 Nanoparticles of ZnFe 2 O 4 BiOCl (001) complex for photocatalytic reduction of CO in cyclohexanol 2 The catalyst shows good catalytic activity in an activity test for preparing organic compounds and has a flaky structure ZnFe 2 O 4 Compared with the BiOCl compound, the production quantity of the target product is greatly improved. Three-dimensional ZnFe of the invention 2 O 4 the/BiOCl (001) composite photocatalyst has the advantages of simple preparation process, controllable catalyst morphology and crystal form and good catalytic activity.)

1. Three-dimensional ZnFe₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized by comprising the following steps:

adding a mixture of bismuth nitrate and potassium chloride into distilled water, and uniformly stirring to obtain a first mixed solution; wherein the molar ratio of the bismuth nitrate to the potassium chloride is 1: 1; the concentration of the bismuth nitrate in the first mixed solution is 0.05-0.1 mol/L;

adding oleylamine into the first mixed solution, and uniformly mixing to obtain a bismuth oxychloride precursor solution; wherein the concentration of oleylamine in the bismuth oxychloride precursor solution is 0.01-0.02 mol/L;

transferring the bismuth oxychloride precursor solution into a hydrothermal kettle, carrying out hydrothermal reaction for 20-24h at the temperature of 140-180 ℃, cooling, separating out a gray precipitate, washing and drying the gray precipitate to obtain bismuth oxychloride (001);

dissolving zinc ferrite and zinc nitrate in water, and adding the bismuth oxychloride in the process of uniformly stirring until the bismuth oxychloride is fully mixed to obtain a second mixed solution;

adding a mixed solution of ethylene glycol and sodium acetate into the second mixed solution, and continuously stirring to obtain a reddish brown precursor solution;

transferring the reddish brown precursor solution into a hydrothermal kettle, carrying out hydrothermal reaction for 10-13h at the temperature of 120-130 ℃, separating out light red precipitate after cooling, and washing and drying the light red precipitate to obtain three-dimensional ZnFe₂O₄the/BiOCl (001) composite photocatalyst.

2. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that the gray precipitate is washed and dried to obtain bismuth oxychloride, and the drying temperature is 80 ℃ and the drying time is 12 hours.

3. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that the molar ratio of zinc ferrite to zinc nitrate is 1: 1.

4. the three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that the preparation method comprises the step of preparing three-dimensional ZnFe₂O₄ZnFe in/BiOCl (001) composite photocatalyst₂O₄The mass percentage of the component (A) is 3-8%.

5. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that the ethylene glycol/sodium acetate mixed solution is formed by mixing ethylene glycol and sodium acetate, and the concentration of the ethylene glycol in the ethylene glycol/sodium acetate mixed solution is 0.01-0.02 mol/L.

6. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl composite photocatalyst is characterized in that the light red precipitate is washed and dried at the drying temperature of 80 ℃ for 10 hours.

7. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that in the process of washing and drying the gray precipitate, the washing method comprises the steps of sequentially washing the gray precipitate by deionized water and absolute ethyl alcohol, and then drying the washed gray precipitate.

8. The three-dimensional ZnFe of claim 1₂O₄The preparation method of the/BiOCl (001) composite photocatalyst is characterized in that in the process of washing and drying the light red precipitate, the washing method comprises the steps of washing the light red precipitate by deionized water and absolute ethyl alcohol in sequence, and then drying the washed light red precipitate.

9. Three-dimensional ZnFe₂O₄A/BiOCl (001) composite photocatalyst, which is prepared by the method for preparing the composite photocatalyst as claimed in any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of composite photocatalysts, in particular to a three-dimensional ZnFe₂O₄/BiOCl (001) composite photocatalyst and a preparation method thereof.

Background

Conversion of CO by photocatalytic technology₂Can simultaneously solve the problem of energy shortage and CO₂Increasing the global warming problem that arises. Due to CO₂Stable molecular structure, and current photocatalytic conversion of CO₂The process has the problems of low conversion rate, complex product and the like, so the research on the photocatalyst still improves CO₂The key to conversion.

Bismuth oxychloride is a ternary semiconductor photocatalyst, the conduction band position (ECB ═ 1.1vvs. nhe, pH ═ 7), itself has a layered structure and high photochemical stability, there is an internal electrostatic field self-established along the (001) direction, the electric field between bismuth layer and chlorine layer is favorable for the effective separation of photogenerated carriers, the catalyst has been proved to have excellent photocatalytic performance, and has attracted extensive attention in the environmental field.

Studies have shown that the (001) crystal plane-exposed BiOCl contains a higher density of terminal oxygen atoms than the (010) crystal plane BiOCl, and therefore oxygen vacancies are more easily formed. The density functional theory calculation shows that the BiOCl unit of the (001) crystal face has clear Bi₂O₂]Layer and halogen layer, BiOCl of this structure has high thermodynamic stability and ability to effectively separate electron-hole. The photocatalyst with the three-dimensional microsphere structure can obtain stronger absorption through multi-surface reflection energy of light, the BiOCl with the exposed (001) crystal surface is prepared into the three-dimensional structure, more terminal oxygen atoms with high density can be exposed to form more active sites, the absorption of the catalyst in a visible light driver is enhanced, the transfer of a photon-generated carrier can be improved, and oxygen vacancies are beneficial to adsorbing and activating CO on the surface of the catalyst₂This will be more advantageous in improving the photocatalytic efficiency than the sheet structure BiOCl (001).

Zinc ferrite (ZnFe)₂O₄) Is a narrow band (1.8-1.9 eV) magnetic semiconductor material with better response in a visible light region, and ZnFe₂O₄The conduction band position (ECB is-1.5 Vvs. NHE, pH is 7), has the advantages of stable chemical property, low price, no toxicity and the like, and has application in biotechnology, photocatalytic degradation of organic matters, water decomposition and the like. Zinc ferrite is deposited on the surface of the bismuth oxychloride with the three-dimensional structure to form the composite catalyst, so that the photocatalytic activity of the bismuth oxychloride can be effectively improved, the recombination of photo-generated electrons and holes can be inhibited, and the response of the catalyst in a visible light region can be increased.

Disclosure of Invention

In view of the problems in the background art, the invention aims to provide three-dimensional ZnFe₂O₄The preparation method has simple process and controllable catalyst appearance, and can be used for photocatalytic reduction of CO₂To enhance the photocatalytic reduction of CO₂The conversion rate of (c).

In a first aspect, the embodiments of the present invention provide a three-dimensional ZnFe₂O₄The preparation method of the/BiOCl (001) composite photocatalyst comprises the following steps:

s110, adding a mixture of bismuth nitrate and potassium chloride into distilled water, and uniformly stirring to obtain a first mixed solution; wherein the molar ratio of the bismuth nitrate to the potassium chloride is 1: 1; the concentration of the bismuth nitrate in the first mixed solution is 0.05-0.1 mol/L;

s120, adding oleylamine into the first mixed solution, and uniformly mixing to obtain a bismuth oxychloride precursor solution; wherein the concentration of oleylamine in the bismuth oxychloride precursor solution is 0.01-0.02 mol/L;

s130, transferring the bismuth oxychloride precursor liquid into a hydrothermal kettle, carrying out hydrothermal reaction for 20-24h at the temperature of 140-180 ℃, cooling, separating out a gray precipitate, and washing and drying the gray precipitate to obtain bismuth oxychloride;

s140, dissolving zinc ferrite and zinc nitrate in water, and adding the bismuth oxychloride in the process of uniformly stirring until the bismuth oxychloride is fully mixed to obtain a second mixed solution;

s150, adding a mixed solution of ethylene glycol and sodium acetate into the second mixed solution, and continuously stirring to obtain a reddish brown precursor solution;

s160, transferring the reddish brown precursor liquid into a hydrothermal kettle, carrying out hydrothermal reaction for 10-13h at the temperature of 120-130 ℃, separating a light red precipitate after cooling, and washing and drying the light red precipitate to obtain three-dimensional ZnFe₂O₄the/BiOCl (001) composite photocatalyst.

Optionally, washing and drying the gray precipitate to obtain bismuth oxychloride, wherein the drying temperature is 80 ℃ and the drying time is 12 hours.

Optionally, the molar ratio of zinc ferrite to zinc nitrate is 1: 1.

optionally, ZnFe₂O₄ZnFe in/BiOCl (001) composite photocatalyst₂O₄The mass percentage of the component (A) is 3-8%.

Optionally, the ethylene glycol/sodium acetate mixed solution is formed by mixing ethylene glycol and sodium acetate, and the concentration of ethylene glycol in the ethylene glycol/sodium acetate mixed solution is 0.01-0.02 mol/L.

Optionally, the light red precipitate is washed and dried at 80 ℃ for 10 hours.

Optionally, in the washing and drying of the gray precipitate, the washing method includes washing the gray precipitate with deionized water and absolute ethyl alcohol in sequence, and then drying the washed gray precipitate.

Optionally, in the washing and drying of the light red precipitate, the washing method includes washing the light red precipitate with deionized water and absolute ethyl alcohol in sequence, and then drying the washed light red precipitate.

In a second aspect, embodiments of the present invention provide a three-dimensional ZnFe₂O₄the/BiOCl (001) composite photocatalyst is prepared by the preparation method of the composite photocatalyst.

The invention prepares a three-dimensional ZnFe₂O₄the/BiOCl (001) composite photocatalyst takes oleylamine as morphology guideA crystal face control agent, a hydrothermal method is used for preparing BiOCl (001) with a three-dimensional microsphere structure at the temperature of 140-180 ℃, and ZnFe is deposited on the surface of the BiOCl (001)₂O₄Nanoparticles of ZnFe₂O₄BiOCl (001) complex for photocatalytic reduction of CO in cyclohexanol₂The catalyst shows good catalytic activity in an activity test for preparing organic compounds and has a flaky structure ZnFe₂O₄The yield of the target product is greatly increased compared with that of the/BiOCl (001) complex. Three-dimensional ZnFe of the invention₂O₄the/BiOCl (001) composite photocatalyst has the advantages of simple preparation process, controllable catalyst morphology and crystal form and good catalytic activity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a scanning electron micrograph of three-dimensional bismuth oxychloride (001) prepared in example 1;

FIG. 2 is the three-dimensional ZnFe prepared in example 1₂O₄A scanning electron microscope image of the BiOCl (001) composite photocatalyst;

FIG. 3 shows three-dimensional bismuth oxychloride (001) and ZnFe prepared in example 1₂O₄XRD pattern of the/BiOCl (001) composite photocatalyst;

FIG. 4 shows three-dimensional ZnFe prepared in example 1, example 2 and example 3₂O₄Photocatalytic reduction of CO in cyclohexanol by using/BiOCl (001) composite photocatalyst₂And the quantity of the generated Cyclohexyl Formate (CF) is subjected to esterification reaction along with the change of time; in the figure, line BOC is a pure BiOCl sample, line BOCZ-1 is the sample prepared in example 1, line BOCZ-2 is the sample prepared in example 2, and line BOCZ-3 is the sample prepared in example 3;

FIG. 5 shows three-dimensional ZnFe prepared in example 1, example 2 and example 3₂O₄Photocatalytic reduction of CO in cyclohexanol by using/BiOCl (001) composite photocatalyst₂The amount of cyclohexanol oxidized to Cyclohexanone (CH) as a function of timeAnd (5) forming a relational graph. In the figure, line BOC is a pure BiOCl sample, line BOCZ-1 is the sample prepared in example 1, line BOCZ-2 is the sample prepared in example 2, and line BOCZ-3 is the sample prepared in example 3;

FIG. 6 is a scanning electron micrograph of bismuth oxychloride prepared in example 2;

FIG. 7 shows ZnFe prepared in example 2₂O₄A scanning electron microscope image of the BiOCl composite photocatalyst;

FIG. 8 is a scanning electron micrograph of bismuth oxychloride prepared in example 3;

FIG. 9 is the ZnFe prepared in example 2₂O₄A scanning electron microscope image of the BiOCl composite photocatalyst;

FIG. 10 is ZnFe provided in the examples₂O₄A flow chart of a preparation method of the BiOCl composite photocatalyst.

Detailed Description

The technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention.

The three-dimensional hierarchical structure bismuth oxychloride (BiOCl) microsphere composed of the nano sheets which are staggered with each other can obtain strong absorption through multi-surface reflection of light, the bismuth oxychloride microsphere composed of the nano sheets with exposed (001) crystal surfaces can expose more high-density terminal oxygen atoms, more active sites are formed, the transfer rate of photo-generated carriers is improved, and the photocatalytic reduction of CO is improved₂Efficiency. The surface of bismuth oxychloride (001) is loaded with zinc ferrite (ZnFe)₂O₄) The nano particles are beneficial to improving the separation of photo-generated electrons and holes, widening the response of bismuth oxychloride in a visible light region and improving the photocatalytic activity. At present, ZnFe is used for the three-dimensional microsphere structure₂O₄Preparation of/BiOCl (001) composite photocatalyst and application of photocatalyst in photocatalytic reduction of CO₂Research is carried out to develop a three-dimensional ZnFe with high activity and good stability₂O₄A/BiOCl (001) composite photocatalyst is necessary.

The technical preparation method provided by the embodiment of the invention adopts the raw materials of bismuth nitrate, potassium chloride, oleylamine, zinc ferrite, zinc nitrate, ethylene glycol and sodium acetate.