阅读说明：本技术 一种富铋型二维纳米卤氧化铋基光催化剂的制备方法 (Preparation method of bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst ) 是由 万俊 孙凯龙 付峰 刘琳 王雪敏 刘萌 刘佳庆 黎小松 于 2020-05-14 设计创作，主要内容包括：本发明提供了一种富铋型二维纳米卤氧化铋基光催化剂的制备方法,属于光催化技术领域。本发明提供的制备方法包括以下步骤：将铋源溶液、卤化盐和氨水溶液混合,得到悬浊液；将所述悬浊液进行溶剂热反应,得到富铋型二维纳米卤氧化铋基光催化剂；所述溶剂热反应的温度为100～220℃。本发明采用简单的一步溶剂热反应,通过反应温度条件的控制,可得到不同的单体卤氧化铋以及卤氧化铋固溶体和复合物卤氧化铋体系,制备工艺简单,产品种类多样,成本低廉,操作重复性好,产率高。本发明所述方法所制备的催化剂具有均相结构且具有高效的可见光光催化活性,对有机污染物的降解具有显著效果,在能源、环境污染物治理等方面具有广阔的应用前景。(The invention provides a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst, belonging to the technical field of photocatalysis. The preparation method provided by the invention comprises the following steps: mixing a bismuth source solution, a halide salt and an ammonia water solution to obtain a suspension; carrying out solvothermal reaction on the suspension to obtain a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst; the temperature of the solvothermal reaction is 100-220 ℃. The invention adopts simple one-step solvothermal reaction, can obtain different monomer bismuth oxyhalide, bismuth oxyhalide solid solution and compound bismuth oxyhalide systems by controlling the reaction temperature condition, and has the advantages of simple preparation process, various product types, low cost, good operation repeatability and high yield. The catalyst prepared by the method has a homogeneous structure, has high-efficiency visible light photocatalytic activity, has a remarkable effect on degradation of organic pollutants, and has a wide application prospect in the aspects of energy, environmental pollutant treatment and the like.)

1. A preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst is characterized by comprising the following steps:

mixing a bismuth source solution, a halide salt and an ammonia water solution to obtain a suspension;

carrying out solvothermal reaction on the suspension to obtain a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst;

the temperature of the solvothermal reaction is 100-220 ℃.

2. The method of claim 1, wherein the bismuth source in the bismuth source solution comprises bismuth nitrate pentahydrate.

3. The preparation method according to claim 2, wherein the solvent of the bismuth source solution is ethylene glycol, and the dosage ratio of the bismuth source to the ethylene glycol is (2-10) mmol:40 mL.

4. The preparation method of claim 2, wherein the halide salt comprises one or more of a chloride salt, a bromide salt and an iodide salt, the chloride salt comprises potassium chloride or sodium chloride, the bromide salt comprises potassium bromide or sodium bromide, and the iodide salt comprises potassium iodide or sodium iodide; the molar amount of the halide salt is the same as the molar amount of the bismuth source.

5. The preparation method according to claim 1, wherein the mass concentration of the aqueous ammonia solution is 5-25%, and the volume ratio of the aqueous ammonia solution to the bismuth source solution is 1: 2.

6. The method according to any one of claims 1 to 5, wherein the mixing comprises: and adding the halide salt into the bismuth source solution, carrying out first stirring, then adding an ammonia water solution into the obtained mixed solution, and carrying out second stirring to obtain a suspension.

7. The method according to claim 6, wherein the first stirring time is 10 to 60min, and the second stirring time is 1 to 5 hours.

8. The preparation method according to claim 1, wherein the temperature of the solvothermal reaction is 120-200 ℃ and the time is 16-24 h.

9. The method according to claim 1, further comprising, after the solvothermal reaction: and cooling the obtained material to room temperature, and sequentially carrying out centrifugal separation, washing, drying and grinding to obtain the bismuth-rich two-dimensional nano bismuth oxyhalide photocatalyst.

10. The preparation method according to claim 9, wherein the drying temperature is 50-100 ℃ and the drying time is 6-12 h.

Technical Field

The invention relates to the technical field of photocatalysis, in particular to a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst.

Background

In recent years, the photocatalytic technology is considered as one of effective technologies for solving energy problems and environmental pollution, and is widely researched, and the search for a photocatalyst which is cheap, efficient, wide in spectral response range and environment-friendly is always the core of research on the photocatalytic technology. Among numerous visible light response semiconductor photocatalysts, bismuth oxyhalide, as a typical Bi-based semiconductor photocatalyst, has the advantages of no toxicity, low price, corrosion resistance and stable chemical properties and optical properties, and is widely applied to the aspects of photocatalytic energy conversion and pollutant treatment.

For the traditional bismuth oxyhalide BiOX (X ═ Cl, Br and I), due to the limitation of the band structure of an intrinsic semiconductor, the bismuth oxyhalide BiOX cannot simultaneously give consideration to a wide photoresponse range and good redox capability of a catalyst, and the photocatalytic activity of the BiOX is greatly limited. Meanwhile, the BiOX photo-generated electrons and holes are easy to combine, so that the photocatalysis efficiency is low, and the application of the BiOX photo-generated electrons and holes in photocatalysis is restricted. The valence band of bismuth oxyhalide is mainly composed of O2p state and Xnp state (X ═ Cl, Br, I; n ═ 3,4), the conduction band is generally composed of Bi6p state, and the band structure of bismuth oxyhalide is closely related to the ratio and kind of each component atom. Research shows that the bismuth-rich bismuth oxyhalide (Bi) is synthesized_mO_nX_p(ii) a X ═ Cl, Br, I; m is more than p), the composition of the valence band can be changed, the energy band structure can be changed, the photoresponse range and the redox capability of the catalyst can be changed, and the photocatalytic activity of the catalyst can be promoted (for example, Applied Catalysis B: Env)ironmental 2020,262,118262 and Journal of Colloid and interface Science,2019,534, 301-311). Alternatively, by forming a solid solution of bismuth oxyhalide (e.g., BiOCl)_1-xBr_x、BiOCl_1-xI_xAnd BiOBr_1-xI_xPatent 201711196343.X) and constructing bismuth oxyhalide composite systems can effectively improve the photo-generated charge separation efficiency of the catalyst, and show more excellent photocatalytic performance than single bismuth oxyhalide. In addition, if the bismuth oxyhalide material is controlled to synthesize the ultrathin two-dimensional nanosheet structure, more active sites can be provided for catalytic reaction, the path of a photon-generated carrier from a bulk phase to a surface is remarkably shortened, the separation efficiency of the photon-generated carrier in the migration process is improved, and the photocatalytic activity is favorably improved.

At present, researches on bismuth-rich bismuth oxyhalide solid solutions or bismuth-rich bismuth oxyhalide compound systems are few, and two-step synthesis methods are generally adopted, such as two-step method for preparing micron spherical Bi through solvothermal reaction and normal temperature hydrolysis reaction in the Applied Catalysis B (Environmental 2017,203,633-640.) of the university of south Yang university₄O₅Br_xI_2-xSolid solution, Applied Catalysis B: Environmental 2016,199,75-86. at Chinese geological university, micron spherical BiOI @ Bi prepared by hydrothermal method and precipitation method₁₂O₁₇Cl₂However, the synthesis method of the composite system is complex, the micro-sphere structure is not favorable for the full catalytic reaction, and the composite system is mostly of a two-phase structure and needs to be further improved. There is currently no method for preparing a variety of homogeneous bismuth-rich bismuth oxyhalide monomer, solid solution, and composite systems by only one process. Therefore, the development of a novel simple and efficient preparation method for synthesizing the bismuth-rich bismuth oxyhalide-based photocatalyst with a two-dimensional nano structure is of great significance.

Disclosure of Invention

The invention aims to provide a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst, which can be used for preparing different monomer bismuth oxyhalide, bismuth oxyhalide solid solutions and a compound bismuth oxyhalide system, and has the advantages of simple process, various product types, low cost, good operation repeatability and high catalytic performance of the catalyst.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst, which comprises the following steps:

mixing a bismuth source solution, a halide salt and an ammonia water solution to obtain a suspension;

carrying out solvothermal reaction on the suspension to obtain a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst;

the temperature of the solvothermal reaction is 100-220 ℃.

Preferably, the bismuth source in the bismuth source solution comprises bismuth nitrate pentahydrate.

Preferably, the solvent of the bismuth source solution is ethylene glycol, and the dosage ratio of the bismuth source to the ethylene glycol is (2-10) mmol:40 mL.

Preferably, the halide salt comprises one or more of a chloride salt, a bromide salt and an iodide salt, the chloride salt comprises potassium chloride or sodium chloride, the bromide salt comprises potassium bromide or sodium bromide, and the iodide salt comprises potassium iodide or sodium iodide; the molar amount of the halide salt is the same as the molar amount of the bismuth source.

Preferably, the mass concentration of the ammonia water solution is 5-25%, and the volume ratio of the ammonia water solution to the bismuth source solution is 1: 2.

Preferably, the mixing process comprises: and adding the halide salt into the bismuth source solution, carrying out first stirring, then adding an ammonia water solution into the obtained mixed solution, and carrying out second stirring to obtain a suspension.

Preferably, the first stirring time is 10-60 min, and the second stirring time is 1-5 h.

Preferably, the temperature of the solvothermal reaction is 120-200 ℃ and the time is 16-24 h.

Preferably, after the solvothermal reaction, the method further comprises: and cooling the obtained material to room temperature, and sequentially carrying out centrifugal separation, washing, drying and grinding to obtain the bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst.

Preferably, the drying temperature is 50-100 ℃, and the drying time is 6-12 h.

The invention provides a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst, which comprises the following steps: mixing a bismuth source solution, a halide salt and an ammonia water solution to obtain a suspension; carrying out solvothermal reaction on the suspension to obtain a bismuth-rich two-dimensional nano bismuth oxyhalide photocatalyst; the temperature of the solvothermal reaction is 100-220 ℃. The invention adopts simple one-step solvothermal reaction, can obtain different monomer bismuth oxyhalide, bismuth oxyhalide solid solution and compound bismuth oxyhalide systems by controlling the reaction temperature condition, and has the advantages of simple process, various product types, low cost, good operation repeatability and high yield.

The photocatalyst prepared by the method has a homogeneous two-dimensional nanosheet structure, is adjustable in shape, can realize effective regulation and control of the microscopic shape of the catalyst, and provides an idea for improving the activity of the catalyst structurally.

The catalyst prepared by the method has high-efficiency visible light photocatalytic activity, has a remarkable effect on degradation of organic pollutants, and has wide application prospects in the aspects of energy, environmental pollutant treatment and the like.

Drawings

FIG. 1 is an XRD pattern of a bismuth-rich bismuth oxybromide catalyst prepared under different reaction temperature conditions in example 1;

FIG. 2 shows Bi prepared under different ammonia concentrations in example 2₂₄O₃₁Br₁₀XRD pattern of the catalyst;

FIG. 3 shows Bi (a) prepared in example 2₂₄O₃₁Br₁₀-1、(b)Bi₂₄O₃₁Br₁₀-3、(c)Bi₂₄O₃₁Br₁₀SEM picture of-5;

FIG. 4 shows different Bi prepared in example 2₂₄O₃₁Br₁₀The effect diagram of the photocatalyst for degrading tetracycline hydrochloride under visible light;

FIG. 5 is an XRD pattern of the photocatalyst prepared in example 3;

FIG. 6 is a TEM, STEM and Mapping plot of the photocatalyst prepared in example 3;

FIG. 7 is a graph showing the effect of degrading tetracycline hydrochloride by the photocatalyst prepared in example 3;

FIG. 8 is an XRD pattern of the photocatalyst prepared in example 4;

FIG. 9 is a TEM, STEM and Mapping plot of the photocatalyst prepared in example 4;

FIG. 10 shows Bi prepared in example 5₄O₅I₂/Bi₂₄O₃₁Br₁₀XRD pattern of the composite photocatalyst;

FIG. 11 is a TEM, STEM, and Mapping plot of the photocatalyst prepared in example 5.

Detailed Description

The invention provides a preparation method of a bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst, which comprises the following steps:

mixing a bismuth source solution, a halide salt and an ammonia water solution to obtain a suspension;

carrying out solvothermal reaction on the suspension to obtain a bismuth-rich two-dimensional nano bismuth oxyhalide photocatalyst;

the temperature of the solvothermal reaction is 100-220 ℃.

In the present invention, unless otherwise specified, all the starting materials required for the preparation are commercially available products well known to those skilled in the art.

The method mixes the bismuth source solution, the halide salt and the ammonia solution to obtain the suspension. In the present invention, the bismuth source in the bismuth source solution preferably includes bismuth nitrate pentahydrate; the solvent of the bismuth source solution is preferably ethylene glycol; the preparation process of the bismuth source solution is preferably to dissolve the bismuth source in ethylene glycol and stir for 10-60 min to form a clear solution, namely the bismuth source solution. The stirring process is not specially limited, and a uniform and clear solution can be obtained. In the present invention, the ratio of the bismuth source to ethylene glycol is preferably (2 to 10) mmol, more preferably (3 to 8) mmol, and still more preferably (5 to 6) mmol, 40 mL.

In the invention, the halide salt preferably comprises one or more of a chloride salt, a bromide salt and an iodide salt, the chloride salt preferably comprises potassium chloride or sodium chloride, the bromide salt preferably comprises potassium bromide or sodium bromide, and the iodide salt preferably comprises potassium iodide or sodium iodide; when the halide salts are the above, the molar ratio of the different halide salts is not particularly limited; the molar amount of the halide salt is preferably the same as the molar amount of the bismuth source.

In the invention, the mass concentration of the ammonia water solution is preferably 5-25%, more preferably 10-20%, and further preferably 12-16%; the volume ratio of the ammonia water solution to the bismuth source solution is preferably 1: 2.

In the present invention, the mixing process preferably includes: and adding the halide salt into the bismuth source solution, carrying out first stirring, then adding an ammonia water solution into the obtained mixed solution, and carrying out second stirring to obtain a suspension. In the present invention, the manner of adding the aqueous ammonia solution is preferably dropwise, and the rate of dropwise addition is not particularly limited in the present invention, and may be performed by a process well known in the art. In the invention, the first stirring time is preferably 10-60 min, more preferably 30-50 min, and the second stirring time is preferably 1-5 h, more preferably 2-3 h. In the present invention, the first stirring and the second stirring are not particularly limited in speed, and a uniform suspension can be obtained. According to the invention, the shape of the photocatalyst is regulated by using ammonia water, the release speed and concentration of OH & lt- & gt in a solution can be effectively controlled by the alkalescence of the photocatalyst, the synthesis of the ultrathin two-dimensional nanosheet-structured bismuth oxyhalide is facilitated, and the crystal face exposure and the micro-morphology of the catalyst can be effectively regulated by the concentration of the ammonia water in the reaction process. In the second stirring process, the bismuth source and OH in the ammonia water solution^-And halogen X^-、Y^-Reaction of (X, Y ═ Cl, Br, and I) produced a precipitate, and a suspension was formed.

After obtaining the suspension, the invention carries out solvothermal reaction on the suspension to obtain the bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst. In the invention, the temperature of the solvothermal reaction is 100-220 ℃, preferably 120-200 ℃, and more preferably 140-180 ℃, more preferably 160 ℃, and the time is preferably 16-24 hours, more preferably 18-22 hours. In the present invention, the solvothermal reaction is preferably carried out in a reaction tank. In the solvent thermal reaction process, under the influence of the reaction temperature condition, the obtained precipitate is further reacted with OH during the second stirring^-Dehalogenation reactions of different degrees occur to form bismuth oxyhalide monomer photocatalysts, bismuth oxyhalide solid solution photocatalysts or bismuth oxyhalide composite photocatalysts with different stoichiometric ratios.

In the present invention, after the solvothermal reaction, the method preferably further comprises: and cooling the obtained material to room temperature, and sequentially carrying out centrifugal separation, washing, drying and grinding to obtain the bismuth-rich two-dimensional nano bismuth oxyhalide-based photocatalyst. In the present invention, the centrifugation process is not particularly limited, and a process known in the art may be used. In the present invention, the washing process preferably includes distilled water washing and absolute ethanol washing sequentially, and the degree of the washing is not particularly limited in the present invention, and the washing may be performed according to a process well known in the art.

In the invention, the drying temperature is preferably 50-100 ℃, more preferably 60-80 ℃, further preferably 70-90 ℃, and the time is preferably 6-12 h, more preferably 7-10 h, further preferably 8-9 h. The process of the present invention is not particularly limited, and may be carried out according to a process known in the art. The particle size of the bismuth-rich two-dimensional nano bismuth oxyhalide photocatalyst obtained after grinding is not particularly limited, and the bismuth-rich two-dimensional nano bismuth oxyhalide photocatalyst can be prepared according to the particle size well known in the art.

The preparation method can synthesize a plurality of bismuth oxyhalide photocatalysts with different stoichiometric ratios by regulating and controlling reaction temperature conditions to obtain photocatalysts with different components, wherein the photocatalysts with different components comprise a monomer photocatalyst, a solid solution photocatalyst or a composite photocatalyst; such as a single photocatalyst Bi₂₄O₃₁Cl₁₀、Bi₄O₅Br₂、Bi₂₄O₃₁Br₁₀Or Bi₄O₅I₂Solid solution photocatalyst Bi₄O₅Br_xI_2-xOr Bi₂₄O₃₁Br_xCl_10-xAnd a composite photocatalyst Bi₄O₅I₂/Bi₂₄O₃₁Br₁₀And the large-scale production is easy to realize.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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.