Preparation method of layered ternary composite photocatalytic material

Abstract

The present invention relates to the preparation of semiconductor materials, and aims to provide a method for preparing a layered ternary composite photocatalytic material. It includes: reacting titanium aluminum carbide with hydrofluoric acid under stirring conditions, washing and drying to obtain a multilayer structured Mxene material; mixing the Mxene material with a dilute hydrochloric acid solution and sodium fluoroborate evenly and then performing a hydrothermal reaction; centrifuging, washing the precipitate, and drying to obtain a MXene-titanium dioxide composite material; then mixing with a bismuth source, a bromine source, and water and performing a hydrothermal reaction, and washing and drying the obtained precipitate to obtain a product. The MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic material prepared by the present invention overcomes the defect that the MXene-titanium dioxide composite material is difficult to utilize visible light; the MXene-titanium dioxide-bismuth oxybromide nanoheterojunction with close interface contact constructed by an in-situ growth method significantly improves the migration ability and separation efficiency of photogenerated electron-hole pairs, and enhances the visible light catalytic decomposition ability of organic pollutants.

Description

Technical Field

[0001] The invention relates to the preparation of semiconductor materials, and in particular to a method for preparing a layered ternary composite photocatalytic material. Background Art

[0002] Semiconductor photocatalytic technology uses solid semiconductor materials as catalysts, and induces redox reactions on the surface of photocatalysts by absorbing photon energy. As a green, clean, efficient and sustainable technology, semiconductor photocatalytic technology has good development prospects and broad application fields, and has received extensive attention and research in the past few decades. Titanium dioxide is the most representative traditional photocatalytic material, which has outstanding performance in pollutant degradation due to its good oxidation ability, low cost, and high stability. However, as a wide bandgap semiconductor (bandgap width is 3.2eV), titanium dioxide has a low utilization rate of sunlight, and single titanium dioxide still has problems such as easy recombination of photogenerated carriers and low quantum efficiency.

[0003] In recent years, MXene materials have attracted attention as a new type of di-transition metal carbide. This material has an excellent hierarchical structure, high conductivity, and high carrier mobility, making it very suitable for use as a co-catalyst in photocatalysis to improve the efficiency of photogenerated carrier separation. However, the visible light response ability of MXene-titanium dioxide composites is still insufficient, and there is still much room for improvement in their photocatalytic performance.

[0004] Therefore, it is necessary to explore the further compounding of semiconductor photocatalytic materials with good visible light response ability and MXene-titanium dioxide materials to construct ternary composite photocatalytic materials and synergistically improve the visible light response ability and photocatalytic quantum efficiency of composite photocatalytic materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a layered ternary composite photocatalytic material.

[0006] To solve the above technical problems, the solution of the present invention is:

[0007] A method for preparing a layered ternary composite photocatalytic material is provided, comprising the following steps:

[0008] (1) Preparation of multilayer Mxene materials

[0009] 1-2 parts by mass of titanium aluminum carbide are added to 24-48 parts by mass of hydrofluoric acid, and reacted under stirring conditions, wherein the mass fraction of hydrofluoric acid is 40%; after the reaction is completed, centrifuge and collect the precipitate, wash the precipitate with water and anhydrous ethanol in turn, and dry to obtain a multilayered Mxene material;

[0010] (2) Preparation of MXene-titanium dioxide composites

[0011] 1 to 4 parts by weight of the MXene material obtained in step (1) are added to 600 parts by weight of a dilute hydrochloric acid solution and mixed evenly; 6 to 18 parts by weight of sodium fluoroborate are added to the mixed solution, stirred evenly, and then transferred to a reactor for hydrothermal reaction; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide composite material;

[0012] (3) Bismuth oxybromide growth control

[0013] According to the molar ratio of bismuth atoms to bromine atoms of 1:2 to 1:1, 8 to 96 parts by weight of a bismuth source and a corresponding proportion of a bromine source are added together with 1 to 2 parts by weight of the MXene-titanium dioxide composite material prepared in step (2) to 1650 parts by weight of water to prepare a mixed solution; after ultrasonic treatment, the mixture is stirred for 1 hour and then poured into a reactor for hydrothermal reaction; after the reaction is completed, the mixture is centrifuged and the precipitate is collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide-bismuth oxybromide layered ternary composite photocatalytic material.

[0014] As a preferred embodiment of the present invention, the reaction temperature under stirring conditions in step (1) is 20 to 60° C. and the reaction time is 12 to 48 hours.

[0015] As a preferred embodiment of the present invention, the molar concentration of the dilute hydrochloric acid solution in step (2) is 1 to 2 mol / L.

[0016] As a preferred embodiment of the present invention, in the hydrothermal reaction in step (2), the filling rate of the reactor is 60-70%, the reaction temperature is 140-180° C., and the reaction time is 4-24 h.

[0017] As a preferred embodiment of the present invention, the bismuth source in step (3) is at least one of bismuth nitrate, bismuth sulfate and bismuth acetate.

[0018] As a preferred embodiment of the present invention, the bromine source in step (3) is at least one of hexadecyltrimethylammonium bromide, potassium bromide and sodium bromide.

[0019] As a preferred embodiment of the present invention, the ultrasonic treatment time in step (3) is 0.5 to 3 hours.

[0020] As a preferred embodiment of the present invention, in the hydrothermal reaction in step (3), the filling rate of the reactor is 60-70%, the reaction temperature is 120-140° C., and the reaction time is 12-48 h.

[0021] The implementation principle of the present invention:

[0022] At present, there are relatively few studies on the development of ternary composite photocatalytic materials based on MXene-titanium dioxide. Existing public literature mainly uses new narrow-bandgap semiconductors such as graphite-like carbon nitride, silver phosphate, and molybdenum disulfide to improve the visible light response ability of MXene-titanium dioxide materials. However, these narrow-bandgap semiconductors are limited by their own insufficient electron-hole separation ability, and the photocatalytic quantum efficiency needs to be improved.

[0023] Therefore, the present invention selects bismuth oxybromide and MXene-titanium dioxide materials for compounding. The crystal structure of bismuth oxybromide consists of bismuth oxygen layer (Bi2O2 2+ ) and halogen layers (Cl-) are arranged alternately. This layered structure can induce the formation of a built-in electric field perpendicular to the bismuth oxide layer and the halogen layer, promoting the separation of electrons and holes.

[0024] The present invention utilizes the partial oxidation of the surface of the MXene matrix to obtain titanium dioxide nanoparticles in situ, and prepares a MXene-titanium dioxide composite material in which MXene and titanium dioxide are firmly combined; then the multilayer structure of the MXene-titanium dioxide composite material is used to promote the adsorption of bismuth oxybromide precursor ions, forming a site for the in-situ hydrothermal growth of bismuth oxybromide, thereby constructing a MXene-titanium dioxide-bismuth oxybromide nanoheterojunction with uniform microscopic morphology and close interface contact, and under the synergistic effect of the built-in electric field of bismuth oxybromide and the nanoheterojunction formed with MXene-titanium dioxide, the separation efficiency of photogenerated electron-hole pairs is improved. Therefore, the electrons and holes generated by bismuth oxybromide excited by visible light can efficiently migrate to MXene-titanium dioxide, and then react with oxygen or water in the environment to generate active species such as superoxide radicals or hydroxyl radicals, thereby improving the visible light catalytic decomposition ability of organic pollutants.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic material prepared by the present invention overcomes the defect that the MXene-titanium dioxide composite material is difficult to utilize visible light.

[0027] 2. The MXene-titanium dioxide-bismuth oxybromide nanoheterojunction with close interface contact constructed by the in-situ growth method of the present invention significantly improves the migration ability and separation efficiency of photogenerated electron-hole pairs, and enhances the visible light catalytic decomposition ability of organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope photograph of the multilayered Mxene material prepared in Example 1.

[0029] Figure 2 This is a scanning electron microscope photograph of the MXene-titanium dioxide composite material prepared in Example 1.

[0030] Figure 3 This is a scanning electron microscope photograph of the MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic material prepared in Example 1. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific embodiments:

[0032] The method for preparing the layered ternary composite photocatalytic material provided by the present invention comprises the following steps:

[0033] (1) Preparation of multilayer Mxene materials

[0034] 1-2 parts by mass of titanium aluminum carbide are added to 24-48 parts by mass of hydrofluoric acid, and the reaction is carried out under stirring conditions at a temperature of 20-60° C. for 12-48 hours; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a multilayered Mxene material;

[0035] (2) Preparation of MXene-titanium dioxide composites

[0036] 1 to 4 parts by weight of the MXene material prepared in step (1) are added to 600 parts by weight of a dilute hydrochloric acid solution having a molar concentration of 1 to 2 mol / L, and mixed evenly; 6 to 18 parts by weight of sodium fluoroborate are added to the mixed solution, stirred evenly, and then transferred to a reactor for hydrothermal reaction; the filling rate of the reactor is 60 to 70%, the reaction temperature is 140 to 180° C., and the reaction time is 4 to 24 hours; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide composite material;

[0037] (3) Bismuth oxybromide growth control

[0038] According to the molar ratio of bismuth atoms to bromine atoms of 1:2 to 1:1, 8 to 96 parts by weight of a bismuth source and a corresponding proportion of a bromine source are taken, together with 1 to 2 parts by weight of the MXene-titanium dioxide composite material prepared in step (2), and added to 1650 parts by weight of water to prepare a mixed solution; the bismuth source is at least one of bismuth nitrate, bismuth sulfate, and bismuth acetate; and the bromine source is at least one of cetyltrimethylammonium bromide, potassium bromide, and sodium bromide.

[0039] After ultrasonic treatment for 0.5 to 3 hours, the mixture is stirred for 1 hour and then poured into a reactor for hydrothermal reaction; the filling rate of the reactor is 60 to 70%, the reaction temperature is 120 to 140°C, and the reaction time is 12 to 48 hours; after the reaction, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide-bismuth oxybromide layered ternary composite photocatalytic material.

[0040] The following examples can enable professionals in this field to more fully understand the present invention, but do not limit the present invention in any way.

[0041] The preparation methods of MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic materials were successfully prepared through 8 examples respectively. The test data in each example are shown in Table 1 below.

[0042] All the reaction raw materials or reagents used in the examples are commercially available products, and the reagents used can be prepared using commercially available reagents. Among them, the mass fraction of hydrofluoric acid is 40%.

[0043] Table 1 Example data table

[0044]

[0045]

[0046] Application method examples:

[0047] The MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic material prepared in each example was used for photocatalytic decomposition of rhodamine B. The specific test method was as follows:

[0048] 50 mg of the prepared MXene-titanium dioxide-bismuth oxybromide ternary composite photocatalytic material was added to 100 ml of a 20 mg / L rhodamine B solution, and the mixed solution was stirred in the dark for 0.5 h to reach adsorption equilibrium. Then, a xenon lamp was used as a light source to illuminate the mixed solution, and a 420 nm cutoff filter was used to filter out ultraviolet light. The mixed solution was stirred continuously during the illumination process. After 75 min of photocatalytic reaction, 5 mL of the solution was taken out, centrifuged and filtered, and the absorbance C of the clear solution was measured using a UV-visible spectrophotometer. t The decomposition rate of rhodamine B was calculated according to the following equation:

[0049] Decomposition rate = (C0-C t ) / C0×100%

[0050] Where C0 is the initial absorbance of the Rhodamine B solution, C t is the absorbance after t time of photocatalytic reaction.

[0051] Technical effect verification:

[0052] The decomposition rate of Rhodamine B in the photocatalytic reaction for 75 minutes was used as an evaluation index of the photocatalytic performance of the catalytic materials in each embodiment, and the specific values ​​are shown in Table 1. It can be seen that the decomposition rate of the catalyst obtained in the present invention is between 74% and 98%, which is generally higher than the decomposition rate of 60% to 80% of the existing typical modified MXene-titania composite material; and the MXene-titania composite material does not have photocatalytic activity under the visible light condition, which is enough to show its technical superiority.

[0053] Finally, it should be noted that the above examples are only specific implementation examples of the present invention. Obviously, the present invention is not limited to the above implementation examples, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for preparing a layered ternary composite photocatalytic material, characterized in that: The method is to obtain titanium dioxide nanoparticles in situ by partial oxidation of the surface of a MXene matrix, thereby obtaining a MXene-titania composite material in which MXene and titanium dioxide are firmly bonded; then, the multilayer structure of the MXene-titania composite material is used to promote the adsorption of bismuth oxybromide precursor ions, thereby forming a site for in-situ hydrothermal growth of bismuth oxybromide, thereby constructing a MXene-titania-bismuth oxybromide nanoheterojunction with uniform microscopic morphology and close interface contact; The specific steps include: (1) Preparation of multilayer MXene materials 1-2 parts by mass of titanium aluminum carbide are added to 24-48 parts by mass of hydrofluoric acid, and the reaction is carried out under stirring conditions, wherein the mass fraction of the hydrofluoric acid is 40%; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a multilayered Mxene material; (2) Preparation of MXene-titanium dioxide composites 1-4 parts by weight of the MXene material prepared in step (1) is added to 600 parts by weight of a dilute hydrochloric acid solution and mixed evenly; 6-18 parts by weight of sodium fluoroborate is added to the mixed solution, stirred evenly and then transferred to a reactor for hydrothermal reaction, the reaction temperature is controlled to be 140-180° C., the reaction time is 4-24 hours, and the filling rate of the reactor is 60-70%; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide composite material; (3) Bismuth oxybromide growth control According to the molar ratio of bismuth atoms to bromine atoms of 1:2 to 1:1, 8 to 96 parts by weight of a bismuth source and a corresponding proportion of a bromine source are added together with 1 to 2 parts by weight of the MXene-titanium dioxide composite material prepared in step (2) to 1650 parts by weight of water to prepare a mixed solution; the bismuth source is at least one of bismuth nitrate, bismuth sulfate and bismuth acetate; the bromine source is at least one of cetyltrimethylammonium bromide, potassium bromide and sodium bromide; after ultrasonic treatment, the mixture is stirred for 1 hour, then poured into a reactor for hydrothermal reaction, the reaction temperature is controlled to be 120 to 140°C, the reaction time is 12 to 48 hours, and the filling rate of the reactor is 60 to 70%; after the reaction is completed, the precipitate is centrifuged and collected, and the precipitate is washed with water and anhydrous ethanol in turn, and dried to obtain a MXene-titanium dioxide-bismuth oxybromide layered ternary composite photocatalytic material.

2. The method according to claim 1, characterized in that: The reaction temperature under stirring conditions in step (1) is 20-60° C. and the reaction time is 12-48 hours.

3. The method according to claim 1, characterized in that: The molar concentration of the dilute hydrochloric acid solution in step (2) is 1-2 mol / L.

4. The method according to claim 1, characterized in that: The ultrasonic treatment time in step (3) is 0.5 to 3 hours.

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