阅读说明：本技术 钼酸铋/碳化钛异质结二维光催化材料及其制备方法和应用 (Bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material and preparation method and application thereof ) 是由 李必胜 赖萃 秦蕾 曾光明 刘希贵 李玲 符玉葵 何江凡 许辅杭 王志红 史晓勋 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种钼酸铋/碳化钛异质结二维光催化材料及其制备方法和应用,该二维光催化材料包括碳化钛纳米片及负载在其上的层状钼酸铋。制备方法包括以下步骤：制备块状碳化钛；利用二甲亚砜制备碳化钛纳米片；通过水热反应制备上述二维光催化材料。本发明二维光催化材料具有价廉易得、光生电子和空穴复合效率低、催化性能强、氧化还原活性好、对环境的危害较少等优点,是一种绿色、经济的光催化材料,能够广泛用于处理环境中的污染物,有着较高的使用价值和较好的应用前景。本发明制备方法具有工艺简单、操作方便、原料成本低、耗能少、耗时短、反应条件温和且易于控制、绿色环保等优点,在功能性纳米材料的合成方面展现了良好的应用前景。(The invention discloses a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, and a preparation method and application thereof. The preparation method comprises the following steps: preparing massive titanium carbide; preparing titanium carbide nanosheets by using dimethyl sulfoxide; the two-dimensional photocatalytic material is prepared through a hydrothermal reaction. The two-dimensional photocatalytic material has the advantages of low price, easy obtainment, low efficiency of recombination of photoproduction electrons and holes, strong catalytic performance, good oxidation-reduction activity, less harm to the environment and the like, is a green and economic photocatalytic material, can be widely used for treating pollutants in the environment, and has higher use value and better application prospect. The preparation method has the advantages of simple process, convenience in operation, low raw material cost, low energy consumption, short time consumption, mild reaction conditions, easiness in control, environmental friendliness and the like, and shows a good application prospect in the synthesis of functional nano materials.)

1. The bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is characterized by comprising layered bismuth molybdate and titanium carbide nanosheets, wherein the layered bismuth molybdate is loaded on the titanium carbide nanosheets.

2. The bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material as claimed in claim 1, wherein the mass ratio of the titanium carbide nanosheets to the layered bismuth molybdate in the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is 1: 500-1: 50.

3. The bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material as claimed in claim 1 or 2, wherein the layered bismuth molybdate is a single-layer layered structure and has a thickness of 1.02 nm; the thickness of the titanium carbide nanosheet is 1.98 nm.

4. The preparation method of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material as claimed in any one of claims 1 to 3, which is characterized by comprising the following steps:

s1, mixing aluminum titanium carbide and a mixed solution of hydrochloric acid/sodium fluoride for water bath reaction, cleaning and drying to obtain blocky titanium carbide;

s2, mixing the blocky titanium carbide obtained in the step S1 with dimethyl sulfoxide, stirring, adding water, performing ultrasonic treatment, filtering, cleaning and drying to obtain a titanium carbide nanosheet;

s3, mixing the titanium carbide nanosheets obtained in the step S2 with an aqueous solution of bismuth nitrate pentahydrate, dropwise adding a mixed aqueous solution of sodium molybdate dihydrate and cetyltrimethylammonium bromide to perform hydrothermal reaction, cleaning, and drying to obtain the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material.

5. The preparation method according to claim 4, wherein in the step S1, the ratio of the aluminum titanium carbide to the mixed solution of hydrochloric acid/sodium fluoride is 0.5 g: 20 mL; the concentration of sodium fluoride in the mixed solution of hydrochloric acid and sodium fluoride is 4 mmol/mL; the water bath reaction is carried out at the temperature of 60 ℃; the water bath reaction time is 24 hours; the cleaning is to alternately clean for 3-5 times by using dilute hydrochloric acid, water and absolute ethyl alcohol; the drying is carried out under vacuum conditions; the drying temperature is 60 ℃; the drying time is 12-24 h.

6. The method according to claim 5, wherein in step S2, the ratio of bulk titanium carbide to dimethyl sulfoxide to water is 0.1 g: 2 mL: 10 mL; the stirring time is 24 hours; the ultrasonic time is 5 h; the cleaning is to alternately clean for 3-5 times by adopting water and ethanol; the drying is carried out under vacuum conditions; the drying temperature is 60-80 ℃; the drying time is 12-24 h.

7. The preparation method according to any one of claims 4 to 6, wherein in step S3, the ratio of the titanium carbide nanosheets, the bismuth nitrate pentahydrate in the aqueous solution of the bismuth nitrate pentahydrate, and the sodium molybdate dihydrate and the cetyltrimethylammonium bromide in the mixed aqueous solution of the sodium molybdate dihydrate and the cetyltrimethylammonium bromide is 0.0012g to 0.0122 g: 2 mmol: 1 mmol: 0.3 g; the hydrothermal reaction is carried out at a temperature of 120 ℃; the time of the hydrothermal reaction is 24 hours; the method also comprises the following steps of: introducing nitrogen into the reaction solution, and stirring for 1 h; the cleaning is to alternately clean for 3-5 times by adopting water and ethanol; the drying is carried out under vacuum conditions; the drying temperature is 60-80 ℃; the drying time is 12-24 h.

8. The application of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material as defined in any one of claims 1 to 3 or the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared by the preparation method as defined in any one of claims 4 to 7 in treatment of antibiotic wastewater.

9. Use according to claim 8, characterized in that it comprises the following steps: mixing a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material with the antibiotic wastewater, stirring under a dark condition to achieve adsorption balance, and carrying out photocatalytic reaction under an illumination condition to complete the treatment of the antibiotic wastewater; the addition amount of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is 0.3g of that added in each liter of antibiotic wastewater.

10. The use according to claim 9, wherein the antibiotic in the antibiotic wastewater is tetracycline; the concentration of the antibiotics in the antibiotic wastewater is 20 mg/L; the stirring time is 0.5-2 h; the time of the photocatalytic reaction is 1.5 h.

Technical Field

The invention belongs to the technical field of functional nano materials, and relates to a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material as well as a preparation method and application thereof.

Background

With the rapid development of industrialization, the demand of society for fossil fuels is increasing, but the combustion of fossil fuels generates a large amount of pollutants, and the pollutants pose a great threat to the health of human bodies. Currently, many methods (e.g., fenton, biological, adsorption, and electrocatalytic methods) have been developed to degrade these contaminants and have achieved good results. However, the methods have certain defects that firstly, the mineralization efficiency of pollutants is low, and many pollutants are degraded to generate intermediate products which still have strong toxicity; secondly, some methods require the input of external energy, increasing the cost of operation. Therefore, there is an urgent need in the present society to develop a green, environmentally friendly, sustainable technology.

Semiconductor photocatalysis technology is a technology which is researched more in recent years and is a technology which uses solar energy as a driving force to remove pollutants and generate new energy. The semiconductor photocatalysis technology is that a semiconductor material is utilized to generate photoproduction electrons and holes under the excitation of illumination, the electrons have stronger reducing capability and can react with dissolved oxygen in water to generate superoxide radical and hydroxyl radical; the photogenerated holes have strong oxidizing property and can react with water to generate hydroxyl radicals, the generated active radicals and the photogenerated holes have oxidizing capability and can attack pollution, so that pollutants are thoroughly removed, but the novel semiconductor photocatalysis technology has a certain shortness, and if the recombination of photogenerated electrons and holes in the existing adopted photocatalyst is fast, the practical application of the semiconductor photocatalysis technology is greatly limited. Therefore, it is the biggest challenge to develop a photocatalyst with a fast separation and transfer of photogenerated electrons and holes.

Currently, bismuth-based semiconductors in developed photocatalysts are paid attention by extensive scientific research works due to their superior physical properties, chemical properties, optical properties and mechanical properties, among which bismuth molybdate is widely studied as a perovskite-like bismuth-based semiconductor because of its unique layered structure, but the recombination rate of photo-generated electrons and holes of bismuth molybdate is large, thus greatly limiting its catalytic performance. It has been reported that when the number of layers of bulk bismuth molybdate is reduced to a single layer or a few layers, the recombination efficiency of photo-generated electrons and holes of the formed two-dimensional layered bismuth molybdate is greatly reduced, because when the number of layers of bismuth molybdate is reduced to a certain thickness, the distance for electrons and holes generated under the illumination condition to migrate to the surface of bismuth molybdate is greatly reduced, thereby reducing the probability of recombination. Although the recombination of the photo-generated electrons and the holes of the two-dimensional layered bismuth molybdate is inhibited to a certain extent, the photo-generated electrons and the holes which are transferred to the surface of the bismuth molybdate still have the probability of recombination, and meanwhile, the two-dimensional layered bismuth molybdate is easy to agglomerate, so that the specific surface area of the two-dimensional layered bismuth molybdate is reduced, and a large number of active sites are further covered. Therefore, how to effectively inhibit the photo-generated electron-hole recombination on the surface of the catalyst to enhance the photocatalytic performance and how to overcome the agglomeration phenomenon of the two-dimensional layered bismuth molybdate to improve the active sites on the surface of the material become important technical problems to be solved urgently in the current research.

Titanium carbide is a layered material, and is expected to be a co-catalyst with excellent performance due to its high electrical conductivity and high carrier mobility. In addition, considering the unique two-dimensional structure of bismuth molybdate, the construction of a 2D/2D bismuth molybdate/titanium carbide heterojunction by combining two-dimensional bismuth molybdate and two-dimensional titanium carbide is an effective method for inhibiting the recombination of photogenerated electrons and holes, but the construction of the novel 2D/2D bismuth molybdate/titanium carbide heterojunction still has some difficulties: (1) the preparation method of the two-dimensional layered material is complex and takes long time; (2) the conditions required in the preparation method of the 2D/2D bismuth molybdate/titanium carbide heterojunction are harsh; (3) the mass ratio of the two components in the 2D/2D bismuth molybdate/titanium carbide heterojunction has a larger influence on the catalytic performance. Therefore, how to obtain the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material with low photoproduction electron and hole recombination efficiency, strong catalytic performance, good oxidation reduction activity and good reusability, and the method for preparing the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, which is matched with the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, has the advantages of simple process, convenient operation, low raw material cost, less energy consumption, short time consumption, mild reaction conditions, easy control and environmental protection, and has very important significance for effectively improving the treatment effect of the semiconductor photocatalytic technology and expanding the application range of the semiconductor photocatalytic technology.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material which is low in photoproduction electron and hole recombination efficiency, strong in catalytic performance, good in oxidation-reduction activity and good in reusability, and a preparation method and application thereof.

In order to solve the technical problems, the invention adopts the technical scheme that:

the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material comprises layered bismuth molybdate and titanium carbide nanosheets, wherein the layered bismuth molybdate is loaded on the titanium carbide nanosheets.

In the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, the mass ratio of the titanium carbide nanosheets to the layered bismuth molybdate is further improved to be 1: 500-1: 50.

In the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, the layered bismuth molybdate is further improved to be of a single-layer layered structure and the thickness of the layered bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is 1.02 nm; the thickness of the titanium carbide nanosheet is 1.98 nm.

As a general technical concept, the invention also provides a preparation method of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, which comprises the following steps:

s1, mixing aluminum titanium carbide and a mixed solution of hydrochloric acid/sodium fluoride for water bath reaction, cleaning and drying to obtain blocky titanium carbide;

s2, mixing the blocky titanium carbide obtained in the step S1 with dimethyl sulfoxide, stirring, adding water, performing ultrasonic treatment, filtering, cleaning and drying to obtain a titanium carbide nanosheet;

s3, mixing the titanium carbide nanosheets obtained in the step S2 with an aqueous solution of bismuth nitrate pentahydrate, dropwise adding a mixed aqueous solution of sodium molybdate dihydrate and cetyltrimethylammonium bromide to perform hydrothermal reaction, cleaning, and drying to obtain the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material.

In the above preparation method, further improvement is provided, in step S1, the ratio of the aluminum titanium carbide to the mixed solution of hydrochloric acid/sodium fluoride is 0.5 g: 20 mL; the concentration of sodium fluoride in the mixed solution of hydrochloric acid and sodium fluoride is 4 mmol/mL; the water bath reaction is carried out at the temperature of 60 ℃; the water bath reaction time is 24 hours; the cleaning is to alternately clean for 3-5 times by using dilute hydrochloric acid, water and absolute ethyl alcohol; the drying is carried out under vacuum conditions; the drying temperature is 60 ℃; the drying time is 12-24 h.

In the above preparation method, further improvement is provided, in the step S2, the ratio of the bulk titanium carbide, the dimethyl sulfoxide and the water is 0.1 g: 2 mL: 10 mL; the stirring time is 24 hours; the ultrasonic time is 5 h; the cleaning is to alternately clean for 3-5 times by adopting water and ethanol; the drying is carried out under vacuum conditions; the drying temperature is 60-80 ℃; the drying time is 12-24 h.

In the step S3, the ratio of the titanium carbide nanosheets, bismuth nitrate pentahydrate in the aqueous solution of bismuth nitrate pentahydrate, and sodium molybdate dihydrate and cetyltrimethylammonium bromide in the mixed aqueous solution of sodium molybdate dihydrate and cetyltrimethylammonium bromide is 0.0012 g-0.0122 g: 2 mmol: 1 mmol: 0.3 g; the hydrothermal reaction is carried out at a temperature of 120 ℃; the time of the hydrothermal reaction is 24 hours; the method also comprises the following steps of: introducing nitrogen into the reaction solution, and stirring for 1 h; the cleaning is to alternately clean for 3-5 times by adopting water and ethanol; the drying is carried out under vacuum conditions; the drying temperature is 60-80 ℃; the drying time is 12-24 h.

As a general technical concept, the invention also provides an application of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material or the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared by the preparation method in treatment of antibiotic wastewater.

The application is further improved, and comprises the following steps: mixing a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material with the antibiotic wastewater, stirring under a dark condition to achieve adsorption balance, and carrying out photocatalytic reaction under an illumination condition to complete the treatment of the antibiotic wastewater; the addition amount of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is 0.3g of that added in each liter of antibiotic wastewater.

In the above application, further improved, the antibiotic in the antibiotic wastewater is tetracycline; the concentration of the antibiotics in the antibiotic wastewater is 20 mg/L; the stirring time is 0.5-2 h; the time of the photocatalytic reaction is 1.5 h.

Compared with the prior art, the invention has the advantages that:

(1) the invention provides a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material which comprises layered bismuth molybdate and titanium carbide nanosheets, wherein the layered bismuth molybdate is loaded on the titanium carbide nanosheets. According to the invention, the layered bismuth molybdate and the titanium carbide nanosheet are two-dimensional materials, wherein the layered bismuth molybdate is used as a main material, the titanium carbide nanosheet is used as a carrier material, the layered bismuth molybdate is attached to the surface of the titanium carbide nanosheet to construct a 2D/2D bismuth molybdate/titanium carbide heterojunction, and a Schottky heterojunction can be generated at an interface. The Schottky heterojunction is a special heterojunction formed on the surfaces of metal and a semiconductor, a built-in electric field is formed at the interface of the Schottky heterojunction, the migration direction of electrons can be regulated and controlled by the existence of the built-in electric field, and the separation of photo-generated electrons and holes can be accelerated. In the invention, the surface of the titanium carbide nanosheet contains a plurality of fluorine groups, hydroxyl groups or oxygen groups, and the groups can be used as active sites to improve the catalytic performance; meanwhile, the surface of the titanium carbide nanosheet contains a plurality of terminal metal sites, so that the titanium carbide nanosheet has strong redox activity, and after the layered bismuth molybdate and the titanium carbide nanosheet are compounded, the titanium carbide nanosheet not only can provide a large number of active sites, but also can improve the redox activity of the composite material. The bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material has the advantages of low efficiency of recombination of photo-generated electrons and holes, strong catalytic performance, good redox activity, good reusability and the like, can be widely used for treating pollutants in the environment, and has high use value and good application prospect; meanwhile, the layered bismuth molybdate is used as a main material, so that the layered bismuth molybdate has the advantages of low price, easiness in obtaining, less harm to the environment and the like, and therefore the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material is a green and economic photocatalytic material.

(2) In the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, the dispersibility of the layered bismuth molybdate can be improved and the effective formation of heterojunction between the titanium molybdate nano-sheet and the layered bismuth molybdate is promoted by optimizing the mass ratio of the titanium molybdate nano-sheet to the layered bismuth molybdate to be 1: 500-1: 50, so that the recombination of photo-generated electrons and holes is reduced, the material has better photocatalytic activity and the photocatalytic effect is improved, because when the mass ratio of the titanium molybdate nano-sheet to the layered bismuth molybdate is smaller, the dispersibility of the layered bismuth molybdate is poor, and a lot of layered bismuth molybdate cannot form effective heterojunction with the titanium molybdate nano-sheet, and at the moment, the recombination rate of electrons and holes is still larger; when the mass ratio of the titanium carbide nanosheet to the layered bismuth molybdate is relatively large, the titanium carbide nanosheet is a black material, has relatively high absorptivity, competes with the layered bismuth molybdate to reduce the sunlight absorption of the material, and reduces the catalytic effect of the material, so that the mass ratio of the titanium carbide nanosheet to the layered bismuth molybdate needs to be optimized to ensure that the material can obtain the optimal catalytic effect.

(3) In the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, the layered bismuth molybdate is of a single-layer layered structure and is 1.02nm thick as a two-dimensional single-layer material, and the ultrathin thickness can further shorten the distance of transmission of photo-generated electrons and holes to the surface of the bismuth molybdate, so that the photo-generated electrons and holes can be more rapidly transferred to the surface of the material, the recombination of the photo-generated electrons and holes is further reduced to a certain extent, and the photocatalytic performance of the composite material is improved. In addition, due to the fact that the thickness and the size of the bismuth molybdate are small, the surface energy of the bismuth molybdate is large, materials with large surface energy are easy to migrate, the bismuth molybdate can be seriously agglomerated, the specific surface area of the bismuth molybdate can be reduced due to the serious agglomeration of the bismuth molybdate, and a large number of active sites can be covered.

(4) The invention provides a preparation method of a bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material, which comprises the steps of firstly preparing massive titanium carbide by taking titanium aluminum carbide as a precursor through a water bath reaction under the action of hydrochloric acid and sodium fluoride, then preparing two-dimensional layered titanium carbide nanosheets by stripping the massive titanium carbide through dimethyl sulfoxide, and finally preparing layered bismuth molybdate by taking bismuth nitrate pentahydrate, sodium molybdate dihydrate and hexadecyl trimethyl ammonium bromide as precursors through an anaerobic hydrothermal method and loading the layered bismuth molybdate on the titanium carbide nanosheets, so that the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material with good catalytic performance and good dispersion performance is prepared. Compared with other methods, the preparation method disclosed by the invention has the advantages of mild reaction conditions, no need of precise instruments, simple process, convenience in operation, low raw material cost, low energy consumption, short time consumption, mild reaction conditions, easiness in control, environmental friendliness and the like, is suitable for continuous large-scale batch production, is convenient for industrial utilization, and shows a good application prospect in the aspect of synthesis of functional nano materials.

(5) The invention also provides the application of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material in the treatment of antibiotic wastewater, and the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material has the advantages of simple process, convenience in operation, low cost, high treatment efficiency and high pollutant degradation efficiency, and has good practical application prospect.

Drawings

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

Fig. 1 is a transmission electron microscope image of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared in the embodiment 3 of the present invention.

Fig. 2 is a high-resolution transmission electron microscope image of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared in example 3 of the present invention.

Fig. 3 is an energy spectrum diagram of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared in the embodiment 3 of the invention.

Fig. 4 is an atomic force microscope image of the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared in example 3 of the present invention.

Fig. 5 is an electrochemical impedance spectrum of the two-dimensional photocatalytic material of bismuth molybdate/titanium carbide heterojunction prepared in example 3 of the present invention.

Fig. 6 is a graph showing the degradation effect of bismuth molybdate on tetracycline, which is the bismuth molybdate/titanium carbide heterojunction two-dimensional photocatalytic material prepared in examples 1 to 4 of the present invention.

Detailed Description

The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.

The materials and equipment used in the following examples are commercially available.