阅读说明：本技术 一种具有同质晶面结的溴氧铋高效光催化剂的制备方法 (Preparation method of bismuth oxybromide efficient photocatalyst with homogenous crystal face junction ) 是由 季梦夏 李华明 夏杰祥 狄俊 尹盛 于 2020-12-16 设计创作，主要内容包括：本发明属于催化剂领域,具体涉及一种具有同质晶面结的溴氧铋高效光催化剂的制备方法。本催化剂通过溶剂热法合成,以五水硝酸铋为铋源,均三溴苄为溴源,制备得到具有(110)/(120)同质晶面结的溴氧铋光催化剂。相比于侧面只暴露(110)或者(120)晶面的溴氧铋材料,该具有(110)/(120)同质晶面结的溴氧铋材料表现出更高的光催化还原二氧化碳的性能。该合成方法操作简单,可重复性高,清洁环保。(The invention belongs to the field of catalysts, and particularly relates to a preparation method of a bismuth oxybromide efficient photocatalyst with a homogeneous crystal face junction. The catalyst is synthesized by a solvothermal method, bismuth nitrate pentahydrate is used as a bismuth source, and sym-tribromobenzyl is used as a bromine source, so that the bismuth oxybromide photocatalyst with a (110)/(120) homogeneous crystal face structure is prepared. Compared with a bismuth oxybromide material with only (110) or (120) crystal planes exposed on the side surface, the bismuth oxybromide material with the (110)/(120) homogeneous crystal plane junction has higher performance of photocatalytic reduction of carbon dioxide. The synthetic method is simple to operate, high in repeatability, clean and environment-friendly.)

1. A preparation method of a bismuth oxybromide high-efficiency photocatalyst with a homogeneous crystal face junction is characterized by comprising the following steps:

(1) adding a proper amount of sym-tribromobenzyl and oleylamine into the mannitol aqueous solution, and continuously stirring at room temperature to obtain a mixed solution A;

(2) adding a proper amount of bismuth nitrate pentahydrate into the mixed solution A obtained in the step (1), and continuously stirring at room temperature to obtain a mixed solution B;

(3) pouring the mixed solution B obtained in the step (2) into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction;

(4) and (4) centrifuging the product obtained in the step (3), washing with deionized water and absolute ethyl alcohol for several times respectively, and drying to obtain the bismuth oxybromide photocatalyst with the homogeneous crystal face structure.

2. The method according to claim 1, wherein in the step (1), the content of bromine in the mixed solution A is 0.01 to 0.1mol/L, the content of oleylamine is 0.01 to 0.05mol/L, and the concentration of the aqueous mannitol solution is 0.01 to 0.15 mol/L.

3. The production method according to claim 1, wherein in the step (2), the content of bismuth in the mixed solution B is 0.002 to 0.008 mol/L.

4. The method according to claim 1, wherein in the step (2), the stirring time at room temperature is 5 to 60 minutes.

5. The method according to claim 1, wherein in the step (3), the reaction temperature is 80 to 150 ℃ and the reaction time is 5 to 24 hours.

6. The method according to claim 1, wherein in the step (4), the drying temperature is 60 ℃ and the drying time is 10 to 20 hours.

7. A bismuth oxybromide high-efficiency photocatalyst with a homogenous crystal face junction is characterized by being prepared by the preparation method of any one of claims 1-6 and being in a nano-sheet shape, and the thickness of the nano-sheet is 1.2 nm.

8. Use of the bismuth oxybromide photocatalyst having a homo-crystal junction according to claim 7 for photocatalytic reduction of carbon dioxide to carbon monoxide.

Technical Field

The invention belongs to the field of preparation of photocatalytic materials, and particularly relates to a preparation method of a bismuth oxybromide photocatalyst with a homogeneous crystal face junction.

Background

Since 2000, the excessive use of fossil fuels led to a rapid increase in global carbon dioxide emissions, creating a new history again in 2019. The annual increase of carbon dioxide emission causes global climate abnormality and accelerates the melting of polar icebergs. Therefore, it is urgent to alleviate excessive dependence on fossil fuels, optimize energy structures, and develop new renewable clean energy. The carbon dioxide is converted into the carbon-based fuel with high added value by utilizing the artificial photosynthesis technology, so that the greenhouse effect can be slowed down, and a new way is provided for diversification of novel energy sources, thereby forming good carbon cycle.

Bismuth oxybromide materials are novel visible light response type photocatalysts, and the interlayer open structural characteristics endow the bismuth oxybromide materials with high adjustability, which are prominent in the fields of photochemical environment restoration and energy conversion in recent years. At present, in the process of photocatalytic reaction, the separation and transmission rate of photo-generated charges are key factors for restricting the photocatalytic performance of the bismuth oxybromide material. Considering that energy level differences exist among different crystal faces, crystal face homojunctions are constructed through surface atomic rearrangement, in-situ high-efficiency separation of photo-generated electron-hole pairs is further induced, the defect that recombination rate of photo-generated carriers in the bismuth oxybromide material is high is remarkably improved, and finally the carbon monoxide is prepared through high-selectivity and high-efficiency photocatalytic reduction of carbon dioxide by the bismuth oxybromide material. At present, no relevant report exists.

Disclosure of Invention

The invention aims to provide a preparation method of a bismuth oxybromide visible light photocatalyst with a homogeneous crystal face junction, which is used for relieving the greenhouse effect and simultaneously provides a new way for developing new energy.

The technical scheme of the invention is as follows:

a preparation method of a bismuth oxybromide high-efficiency photocatalyst with a homogeneous crystal face junction comprises the following steps:

(1) adding a proper amount of sym-tribromobenzyl and oleylamine into the mannitol aqueous solution, and continuously stirring at room temperature to obtain a mixed solution A;

(2) adding a proper amount of bismuth nitrate pentahydrate into the mixed solution A obtained in the step (1), and continuously stirring at room temperature to obtain a mixed solution B;

(3) pouring the mixed solution B obtained in the step (2) into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction;

(4) and (4) centrifuging the product obtained in the step (3), washing with deionized water and absolute ethyl alcohol for several times respectively, and drying to obtain the bismuth oxybromide photocatalyst with the homogeneous crystal face structure.

In the step (1), the content of bromine in the mixed solution A is 0.01-0.1mol/L, the content of oleylamine is 0.01-0.05mol/L, and the concentration of the mannitol aqueous solution is 0.01-0.15 mol/L.

In the step (2), the content of bismuth in the mixed solution B is 0.002-0.008 mol/L.

In the step (2), the stirring time at room temperature is 5-60 minutes.

In the step (3), the reaction temperature is 80-150 ℃, and the reaction time is 5-24 h.

In the step (4), the drying temperature is 60 ℃, and the drying time is 10-20 h.

The bismuth oxybromide visible light response photocatalyst with the homogeneous crystal face junction is in a nanosheet shape, and the thickness of the nanosheet is 1.2 nm.

The bismuth oxybromide photocatalyst with the homogeneous crystal face junction is used for preparing carbon monoxide by photocatalytic reduction of carbon dioxide.

The invention has the beneficial effects that:

compared with the prior art, the bismuth oxybromide material with the homogeneous crystal junctions can realize the photocatalytic conversion of carbon dioxide into carbon monoxide at room temperature without adding a sacrificial agent and a photosensitizer, the selectivity of the product carbon monoxide reaches 100%, and the apparent quantum efficiency under the irradiation of single-wavelength light of 400nm reaches 1.03%, so that a new path is provided for the industrial production of clean fuels such as ethanol.

Drawings

FIG. 1 is an XRD pattern of bismuth oxybromide with a (110)/(120) homocrystal plane junction and a bismuth oxybromide material with only the (110) or (120) crystal plane exposed.

FIG. 2 is a TEM, HRTEM and AFM thickness plot of a bismuth oxybromide material with (110)/(120) homogenous lattice junctions.

FIG. 3 is a TEM and HRTEM image of a bismuth oxybromide material with only the (110) or (120) crystal planes exposed.

FIG. 4 is an activity diagram of carbon monoxide preparation by photocatalytic carbon dioxide reduction using bismuth oxybromide having (110)/(120) homogeneous crystal plane junction and bismuth oxybromide material exposing only (110) or (120) crystal plane under xenon lamp irradiation.

FIG. 5 is a graph showing the yield of carbon monoxide produced by photocatalytic carbon dioxide reduction with bismuth oxybromide having (110)/(120) homogeneous crystal plane junctions under different single-wavelength light irradiation and the corresponding UV-visible diffuse reflectance spectrum.

Detailed Description

Example 1

Adopting sym-tribromobenzyl as raw material, oleylamine as slow release agent, dispersing in 0.01-0.05L mannitol solution, wherein bromine content is 0.01-0.1mol/L, oleylamine content is 0.01-0.05mol/L, concentration of mannitol aqueous solution is 0.01-0.15mol/L, then adding bismuth nitrate pentahydrate as raw material into the solution, wherein bismuth content is 0.002-0.008mol/L, continuously stirring at room temperature for 5-60 minutes, pouring the mixed solution into a high pressure reaction kettle with polytetrafluoroethylene lining, heating for reaction at 80-150 ℃, and reacting for 5-24 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 10-20 hr.

Example 2

Adopting sym-tribromobenzyl as a raw material, oleylamine as a slow release agent, dispersing in 0.01L of mannitol solution, wherein the content of bromine is 0.02mol/L, the content of oleylamine is 0.02/L, the concentration of mannitol aqueous solution is 0.01mol/L, then adding bismuth nitrate pentahydrate as a raw material into the solution, wherein the content of bismuth is 0.002mol/L, continuously stirring at room temperature for 10 minutes, pouring the mixed solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction at the reaction temperature of 80 ℃ for 10 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 10 hr.

Example 3

Adopting sym-tribromobenzyl as a raw material, oleylamine as a slow release agent, dispersing in 0.02L of mannitol solution, wherein the content of bromine is 0.02mol/L, the content of oleylamine is 0.04mol/L, the concentration of mannitol aqueous solution is 0.01mol/L, then adding bismuth nitrate pentahydrate as a raw material into the solution, wherein the content of bismuth is 0.004mol/L, continuously stirring at room temperature for 30 minutes, pouring the mixed solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction at the reaction temperature of 100 ℃ for 10 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 15 hr.

Example 4

Adopting sym-tribromobenzyl as a raw material, oleylamine as a slow release agent, dispersing in 0.03L of mannitol solution, wherein the content of bromine is 0.05mol/L, the content of oleylamine is 0.05mol/L, the concentration of mannitol aqueous solution is 0.15mol/L, then adding bismuth nitrate pentahydrate as a raw material into the solution, wherein the content of bismuth is 0.005mol/L, continuously stirring at room temperature for 60 minutes, pouring the mixed solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction at the reaction temperature of 120 ℃ for 20 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 15 hr.

Comparative example

Preparing a bismuth oxybromide photocatalyst with a side surface only exposing a (110) crystal face: adding 0.5mmol of sodium bromide and 0.16mL of oleylamine into 15mL of 0.1mol/L mannitol solution, then adding 0.05mmol of bismuth nitrate pentahydrate into the solution, stirring at room temperature for 30 minutes, pouring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction at 120 ℃ for 10 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 20 hr.

Comparative example

Preparing a bismuth oxybromide photocatalyst with a side surface only exposing a (120) crystal face: adding 0.05mmol of bismuth nitrate pentahydrate into 10mL of distilled water to prepare solution A, adding 0.5mmol of potassium bromide into 5mL of distilled water in another container to prepare solution B, dropwise adding the solution B into the solution A under the condition of stirring the solution A, stirring the solution A at room temperature for 30 minutes, pouring the solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining, and heating for reaction at 160 ℃ for 24 hours. Centrifuging the obtained product, washing with deionized water and anhydrous ethanol for several times, and drying at 60 deg.C for 20 hr.

FIG. 1 is an XRD pattern of a bismuth oxybromide material having a (110)/(120) homogenous lattice junction and a bismuth oxybromide photocatalytic material exposing only the (110) or (120) lattice planes, wherein BiOBr- (110) is the bismuth oxybromide material exposing only the (110) lattice plane, BiOBr- (110)/(120) is the bismuth oxybromide material having a (110)/(120) homogenous lattice junction, and BiOBr- (120) is the bismuth oxybromide material exposing only the (110) lattice plane, and the spectrum in FIG. 1 corresponds to BiOBr JCPDS # 85-0862.

FIG. 2 is TEM, HRTEM and AFM thickness diagrams of a bismuth oxybromide material with a (110)/(120) homogeneous crystal plane junction, wherein the bismuth oxybromide material with the homogeneous crystal plane junction is a nanosheet and has a thickness of 1.2 nm.

FIG. 3 is TEM and HRTEM images of a bismuth oxybromide material with only (110) or (120) crystal planes exposed, both nanosheets, where a-c are the bismuth oxybromide material with only (110) crystal planes exposed and d-f are the bismuth oxybromide material with only (120) crystal planes exposed.

Fig. 4 is a graph showing activity of photocatalytic carbon dioxide reduction of bismuth oxybromide having (110)/(120) homojunction and a bismuth oxybromide material exposing only (110) or (120) crystal face under xenon lamp irradiation to produce carbon monoxide, wherein BiOBr- (110) is a bismuth oxybromide material exposing only (110) crystal face, BiOBr- (110)/(120) is a bismuth oxybromide material exposing only (110) crystal face, and BiOBr- (120) is a bismuth oxybromide material exposing only (110) crystal face, and it can be seen from fig. 4 that the bismuth oxybromide material having (110)/(120) homojunction has higher performance of photocatalytic carbon dioxide reduction to produce carbon monoxide compared to the bismuth oxybromide material exposing only (110) or (120) crystal face, and the yield of carbon monoxide per gram after 10 hours of irradiation is 680 micromoles.

Fig. 5 is a graph of the yield of carbon monoxide prepared by carbon dioxide reduction catalyzed by bismuth oxybromide having (110)/(120) homogeneous crystal plane junctions under single-wavelength light irradiation of 380nm, 400nm, 420nm and 450nm, respectively, and a corresponding graph of ultraviolet-visible diffuse reflectance spectrum, wherein the light absorption band edge of the bismuth oxybromide material having (110)/(120) homogeneous crystal plane junctions is 455nm, the highest carbon monoxide yield under single-wavelength light irradiation of 400nm is 35 micromoles per gram per hour, and the apparent quantum efficiency is 1.03%.