CN106563437A - Dy-containing nano lamellar structure complex photocatalyst and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of nanometer materials, and in particular relates to a novel photocatalyst containing Dy nano sheet structure complexes and a preparation method thereof. The complex containing Dy nanosheet structure, its chemical formula is [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O, where: pdc is pyridine carboxylic acid molecule; the complex is monoclinic The system, P21/n point group, is a complex 3D structure consisting of repeating [DyCu(pdc) ₂ (OAc) ₂ (H2O) ₂ ]·11H ₂ O units. The unit cell parameters are: a=1.3788(4)nm, α=90°, b=1.1031(3)nm, β=100.300(3)°, c=19.878(5)nm, γ=90°, V=2974.63 nm3, Z=4. In the complex, Cu ²⁺ ions are five-coordinated, and Dy ³⁺ ions are nine-coordinated, forming a three-dimensional network structure. The complex has a relatively uniform lamellar structure and has photocatalytic effect.

Description

A kind of photocatalyst containing Dy nano sheet structure complex and preparation method thereof

technical field

The invention belongs to the technical field of nanometer materials and photocatalytic materials, and in particular relates to a nanosheet structure photocatalyst using a novel Dy-containing complex as a precursor and a preparation method thereof.

Background technique

The design and preparation of metal-ligand compounds have attracted more and more attention. Ligands are mainly responsible for energy absorption and energy transfer. Metal-ligand compounds have important applications in gas physical adsorption, ion exchange and photocatalysis. Due to this unique characteristic, rare earth cuprates have attracted widespread attention and become a research hotspot in the field of materials.

In the prior art, there are many synthetic methods for this type of compound, mainly including the following: (1) Sol-gel method: the hydrolysis of the alkoxide or organic complex of the reactant to generate the corresponding hydroxide Or aqueous oxide sol, then undergo further condensation polymerization to form a gel, and finally separate and dry to obtain a one-dimensional material; (2) Ultrasonic synthesis method: use ammonia water as a precipitant to react with nitrate under ultrasonic conditions, After roasting, the compound of rare earth oxide can be obtained; (3) Spray pyrolysis: the precursor solution containing metal salt is sprayed into the combustion equipment in the form of mist, and at a high temperature above 1000°C, it burns rapidly to form oxide particles, oxidizes After the particles pass through the high-temperature range, the temperature drops and nucleates and grows; (4) Hydrothermal (solvothermal) synthesis method: refers to the reaction in a high-temperature and high-pressure system, using water or organic matter as a solvent, using the anisotropy of the crystal Anisotropic growth characteristics promote the preferential growth of crystals in a certain crystallographic orientation, thereby producing one-dimensional materials; (5) Powder roasting method (also known as ceramic method or solid-state reaction method): the reactants are mixed evenly according to the required ratio , and sintered at high temperature for a long time in the air to obtain the required samples. Although the above methods can be used to prepare this type of composite oxide, the product has more impurities (lower purity), larger particles, poor product uniformity, and the general sintering temperature is higher, and some methods require additional High pressure; the sol-gel method has strict requirements on the precursor components, and the metal alkoxide is expensive, the reaction time is long, and the preparation method is extremely complicated; the metal oxide prepared by the powder roasting method is difficult to control the atomic ratio. And the sintering temperature is higher.

In summary, it is particularly important to study a metal-ligand compound with low production cost and high preparation efficiency.

Contents of the invention

In view of the above problems, the present invention provides a novel photocatalyst containing Dy nanosheet structure complexes and a preparation method thereof. The structure of the complex is relatively uniform lamellar structure, the structure is single and pure, and the powder has photocatalytic effect and can be used for the degradation of industrial organic matter.

In order to achieve the above object, the present invention provides a nanosheet structure complex containing Dy, whose chemical formula is [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O, where: pdc is pyridine Carboxylic acid molecule; the precursor of the complex is monoclinic crystal system, P21/n point group, which is a complex 3D structure consisting of repeated [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O unit composition. The unit cell parameters are: a=1.3788(4)nm, α=90°, b=1.1031(3)nm, β=100.300(3)°, c= 19.878(5)nm, γ=90°, V=2974.63 nm ³ , Z=4. In the complex, Cu ²⁺ ions are five-coordinated, and Dy ³⁺ ions are nine-coordinated, forming a three-dimensional network structure, and the crystal color is light blue.

The Dy-containing nano-sheet structure complex is a precursor of a Dy-containing nano-sheet structure oxide.

In order to achieve the above object, the present invention also provides a method for preparing the above-mentioned novel Dy-containing nanosheet structure oxide, which specifically includes the following steps.

Step 1. Dissolve copper salt and dysprosium salt with a molar ratio of 1:1 in deionized water, and mix well to obtain mixed solution A.

Step 2, dissolving pyridine carboxylic acid in alcohol solution, adding an appropriate amount of alkali solution, adjusting the pH value to 10-12, and obtaining mixed solution B.

Step 3. Mix and stir the solutions A and B. After 30-60 minutes, a blue solution is obtained, and the impurities are removed by filtration to obtain the complex solution C.

Step 4. Take solution C, and let it settle in the air for 1h-10h to obtain light blue polycrystals, which are filtered and dried naturally at room temperature to obtain product D, which is the complex [DyCu(pdc) ₂ (OAc) ₂ ( H ₂ O) ₂ ] · 11H ₂ O.

Step 5. Put the product D into a nitrogen reduction furnace, roast it at a certain temperature, and keep it warm to obtain the desired powder, that is, Dy ₂ Cu ₂ O ₅ oxide.

The copper salt is one or a mixture of soluble copper salts, preferably CuCl ₂ , Cu(NO ₃ ) ₂ or Cu(CH ₃ COO) ₂ ; the The dysprosium salt is one or a mixture of soluble dysprosium salts, preferably one or a mixture of DyCl ₃ , Dy(NO ₃ ) ₃ or Dy(CH ₃ COO) ₃ .

The ratio relationship between the molar dosage of the copper salt and dysprosium salt and the volume dosage of deionized water is: 1mmol:1mmol:10-30ml.

The pyridinecarboxylic acid is one of soluble pyridinecarboxylic acids, preferably 3-4 pyridinecarboxylic acid, 2-6 pyridinecarboxylic acid or 3-5 pyridinecarboxylic acid.

The molar ratio of the pyridine carboxylic acid to the dysprosium salt is 2:1.

The alcohol solution is one of soluble alcohol solutions, preferably one of methanol, ethanol, propanol or butanol.

The alkaline solution is one of soluble alkaline solutions, preferably one of NaOH, KOH, ammonia or triethylamine.

The stirring adopts mechanical stirring or magnetic stirring, and the rotation speed is 500-1000r/min.

The calcination temperature is 800-1000° C., and the temperature is kept for 1-3 hours.

The Dy ₂ Cu ₂ O ₅ oxide prepared above is used for photocatalytic materials, specifically, it can be used for catalyzing methylene blue organic dyes.

Beneficial effects of the present invention.

In the present invention, using pyridine carboxylic acid as a bridging ligand, the soluble salts of copper and dysprosium are dissolved in deionized water according to a certain molar ratio, and lye is added to adjust the pH value to 10-12, and stirred to obtain a light blue solution, which is statically After precipitation and filtration, light blue microcrystals were obtained. Pyridine polyacid is used as a ligand because it has multiple coordination sites and can form a rich coordination structure. We can choose 3,4-pdc acid, 2,6-pdc acid, 3,5-pdc acid as ligands in the preparation process, and the prepared complex has a three-dimensional hollow MOFs structure. Using the complex as a precursor, the Dy ₂ Cu ₂ O ₅ oxide was prepared by sintering under the protection of nitrogen. It is a relatively uniform lamellar structure. It can be seen that different preparation methods have a great influence on the morphology of metal-ligand products. And there is no report about the preparation of dysprosium cuprate by the coordination reduction sintering method.

Since in the complex [DyCu(-pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O, the ratio of Dy atoms to Cu atoms is 1:1, which happens to be the same as the product Dy ₂ Cu ₂ O ₅ , This method is a coordination sintering method, which is a new preparation method. In the preparation of the precursor of this method, the precursor complex has been accurately prepared, so the particles prepared by this method have the advantages of small scale and high purity. In addition, dysprosium cuprate has a photocatalytic effect on the dye methylene blue.

Description of drawings

Figure 1 is a schematic diagram of the coordination environment of Cu(II) and Dy(III) ions in the complex [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O.

Figure 2 is the diffraction pattern of Dy ₂ Cu ₂ O ₅ polycrystalline powder; where a- is the diffraction pattern of Dy ₂ Cu ₂ O ₅ oxide prepared by solution method under the same conditions; b- the Dy ₂ oxide prepared by coordination sintering method Diffraction patterns of Cu ₂ O ₅ oxides.

Figure 3 is a scanning electron microscope image of Dy ₂ Cu ₂ O ₅ oxide; where a- is the morphology of Dy ₂ Cu ₂ O ₅ oxide prepared by solution method under the same conditions; b- Dy ₂ Cu prepared by coordination sintering method ₂ O ₅ oxide morphology.

Figure 4 is the photocatalytic spectrum of Dy ₂ Cu ₂ O ₅ oxide to methylene blue.

detailed description

The present invention will be described in further detail below in conjunction with specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the above content of the present invention belong to the scope of the present invention.

Example 1.

The method for synthesizing a single crystal of a novel Dy-containing nano sheet structure complex specifically comprises: adding 1 mmol CuCl ₂ and 1 mmol DyCl ₃ to a beaker, and adding 10 ml of deionized water. After mixing evenly, solution A was obtained; 2 mmol 3,4 dipicolinic acid was dissolved in 30 ml of absolute ethanol, and 30 ml of triethylamine was added to adjust the pH to 10 to obtain solution B; the solutions A and B were mixed and stirred, and the stirring was turned to The speed is 500r/min. After stirring for 30min, a blue solution is obtained. After filtering to remove impurities, light blue hexagonal microcrystals appear after the resulting solution is left to stand for 3h. Filter and dry naturally at room temperature to obtain Dy-containing nanosheets. Structural complex single crystal. The yield is 45%.

From the novel Dy-containing photocatalyst nanosheet structure complexes prepared in this example, randomly select a blue crystal of 0.2 mm × 0.18 mm × 0.12 mm, use Xcalibur single crystal X-ray diffractometer, use graphite monochromatic The diffraction data were collected by the φ-ω scan mode of the Mo Kα rays (λ=0.71073 nm). Diffraction intensities were Lp corrected. The empirical absorption correction was carried out. The single crystal structure was solved by the direct method, and all non-hydrogen atoms were found by the difference Fourier synthesis method, and the coordinates of all non-hydrogen atoms were corrected by the least square method. The molecular structure formula of the complex is [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O, where Cu(II) and Dy(III) ions coordinate the environment diagram, see Figure 1.

It can be seen from Figure 1 that the single crystal test results of the precursor of the complex show that it belongs to the monoclinic crystal system, the P21/n point group, and is a complex 3D structure consisting of the repeating unit [DyCu(-pdc) ₂ (OAc) ₂ (H ₂ O) ₂ ]·11H ₂ O. Each repeating unit in the crystal structure contains a nine-coordinated Dy ³⁺ unit and a five-coordinated Cu ²⁺ unit. Cu ²⁺ ions are 5-coordinated, tetragonal bipyramidal configuration. Where the equatorial plane is occupied by two N (N1, N2) and two O (O3, O6) atoms from four different pda molecules, and the axial position is occupied by an O4 atom of a coordinated water molecule. The acetic acid ligand connects two Dy atoms, uses two O atoms to chelate and coordinate the Dy atoms, and uses one of the O atoms to bridge the adjacent Dy atom.

The unit cell parameters are: a=1.3788(4)nm, b=1.1031(3)nm, c=19.878(5)nm, α=90°, β=100.300(3)°, γ=90°, V=2974.63 nm ³ , Z=4. In the complex, Cu ²⁺ ions are five-coordinated, and Dy ³⁺ ions are nine-coordinated, forming a three-dimensional network structure, and the crystal color is light blue.

For the bond length and bond angle information of the crystal, see Table 1-2.

Table 1 Bond length information of crystals.

Table 2 Bond length information of crystals.

Example 2.

A kind of synthetic method of novel Dy containing nano lamellar structure oxide, comprises the following steps: in beaker, add 4mmol Cu(NO ₃ ) ₂ , 4mmol Dy(NO ₃ ) ₃ , add deionized water 120ml, after mixing evenly, obtain Solution A: Dissolve 8mmol2, 6-dipicolinic acid in 40ml of methanol, add 30ml of 1/500mol/L sodium hydroxide solution, adjust the pH to 10, and obtain solution B; mix and stir the A and B solutions, and the stirring speed is 800r/min, mixed and stirred for 60min to obtain a blue solution, after filtering to remove impurities, light blue hexagonal microcrystals appeared after the resulting solution was allowed to stand for 3 hours, filtered, and dried naturally at room temperature to obtain a blue single crystal powder, collected The rate is 46%.

Put the single crystal powder into a nitrogen reduction furnace, sinter at 800° C., and keep it warm for 3 hours to obtain Dy ₂ Cu ₂ O ₅ polycrystalline powder.

The powder was tested by a DX2500 X-ray diffractometer. The scanning speed is 0.08°/min, and the 2θ range is 10-90°. The test results are shown in Figure 2; a- is the diffraction pattern of Dy ₂ Cu ₂ O ₅ oxide prepared by solution method under the same conditions; b- coordination sintering Diffraction pattern of Dy ₂ Cu ₂ O ₅ oxide prepared by the method.

It can be seen from Figure 2 that the Dy ₂ Cu ₂ O ₅ oxide prepared by the solution method has miscellaneous peaks, and the Dy ₂ Cu ₂ O ₅ oxide prepared by the coordination sintering method has almost no miscellaneous peaks, indicating that the oxide prepared by this method The purity of the product is high, reaching more than 99%.

Example 3.

A method for synthesizing a novel Dy-containing nanosheet structure oxide, comprising the following steps: add 4mmol Cu(CH ₃ COO) ₂ and 4mmol Dy(CH ₃ COO) ₃ to a beaker, add 80ml of deionized water, and mix well , to obtain solution A; 8mmol 3,4 dipicolinic acid was dissolved in 30ml of butanol, 30ml of 1/500mol/L sodium hydroxide solution, and the pH was adjusted to 11 to obtain solution B; A and B solutions were mixed and stirred, and stirred The number of revolutions is 1000r/min, after mixing and stirring for 40min, a blue solution is obtained, after filtering to remove impurities, light blue hexagonal microcrystals appear after the obtained solution is left to stand for 4h; filter, and dry naturally at room temperature to obtain a blue single Crystal powder, yield 46%.

The single crystal powder was put into a nitrogen reduction furnace, sintered at 1000° C., and kept for 1 hour to obtain Dy ₂ Cu ₂ O ₅ polycrystalline powder.

The scanning electron microscope image of the Dy ₂ Cu ₂ O ₅ oxide in this example is shown in FIG. 3 . Where a-is the morphology of Dy ₂ Cu ₂ O ₅ oxide prepared by solution method under the same conditions; b-is the morphology of Dy ₂ Cu ₂ O ₅ oxide prepared by coordination sintering method. Compared with the Dy ₂ Cu ₂ O ₅ oxide polycrystalline powder prepared by the solution method, the sample prepared by the complex method has a smaller particle size (150-200nm), and presents a lamellar structure with a thickness of about 150nm.

Example 4.

A novel synthesis method of an oxide photocatalyst containing Dy nanosheet structure, comprising the following steps: adding 6mmol CuCl ₂ and 6mmol DyCl ₃ to a beaker, adding 150ml of deionized water, and mixing uniformly to obtain solution A; adding 12mmol3- 5 Dissolve pyridine carboxylic acid in 30ml of propanol, add 40ml of ammonia water, adjust the pH to 12, and obtain solution B; mix and stir the solutions of A and B at a stirring speed of 500r/min, and after mixing and stirring for 60min, a blue solution is obtained. After filtering to remove impurities, light blue microcrystals appeared after the obtained solution was left to stand for 5 hours; filtered and naturally dried at room temperature to obtain blue single crystal powder.

The single crystal powder was put into a nitrogen reduction furnace for sintering at 900° C. and kept for 2 hours to obtain Dy ₂ Cu ₂ O ₅ polycrystalline powder.

Take 5 mg of the polycrystalline powder, put it into a PSX-5009 photocatalytic reactor purchased from PerfectLight, and degrade methylene blue (0.5 g/L) at a wavelength of 360 nm. The degradation curve is shown in Figure 4. It can be seen from Figure 4 that the powder has a good degradation effect on methylene blue.

Claims (10)

1. A nano-sheet structure complex photocatalyst containing Dy, characterized in that, the chemical formula of the nano-sheet structure complex containing Dy is [DyCu(pdc) ₂ (OAc) ₂ (H ₂ O ₎ ] 11H ₂ O, where: pdc is a specific carboxylic acid molecule; the complex is a monoclinic crystal system, P21/n point group, and is a complex 3D structure composed of repeated [DyCu(pdc) (OAc ) (H ₂ O)]·11H ₂ O unit; the unit cell parameters are: a=1.3788(4)nm, α=90°, b=1.1031(3)nm, β=100.300(3)°, c= 19.878(5)nm, γ=90°, V=2974.63nm ³ , Z=4; in the complex, Cu ²⁺ ions are nine-coordinated, Dy ³⁺ ions are five-coordinated, forming a four-dimensional network Structure; the crystal color of the complex is light blue. 2. The photocatalyst of the Dy-containing nano-sheet structure complex according to claim 1, wherein the Dy-containing nano-sheet structure complex is a Dy-containing nano-sheet structure precursor. 3. the preparation method that contains Dy nanosheet structure oxide as claimed in claim 2, is characterized in that, specifically comprises the following steps: Step 1. Dissolve the copper salt and dysprosium salt with a ratio of 1:1 in deionized water, and mix well to obtain solution A; Step 2, dissolving pyridine carboxylic acid in the alcohol solution, and adding an appropriate amount of alkali solution, adjusting the pH value to 10-12 to obtain solution B; Step 3. Mix and stir solutions A and B. After 30-60 minutes, a blue solution is obtained, and filter to remove impurities to obtain solution C; Step 4. The solution C was left to settle for a period of time to obtain a light blue polycrystal, which was filtered and dried at room temperature to obtain the obtained product D; Step 5. Put the product D into a nitrogen reduction furnace, roast it at a certain temperature, and keep it warm to obtain the desired powder, that is, Dy ₂ Cu ₂ O ₅ oxide. 4. preparation method as claimed in claim 3 is characterized in that, described copper salt is the mixture of one or more in soluble copper salt; Described dysprosium salt is one or several in soluble dysprosium salt The mixture of species; the pyridine carboxylic acid is a kind of soluble pyridine carboxylic acid; the alcohol solution is a kind of soluble alcohol solution; the alkali solution is a kind of soluble alkali solution. 5. The preparation method according to claim 1, characterized in that the soluble copper salt is preferably one or a mixture of CuCl ₂ , Cu(NO ₃ ) ₂ or Cu(CH ₃ COO) ₂ ; The soluble dysprosium salt is preferably DyCl ₃ , Dy(NO ₃ ) ₃ , or a mixture of one or more of Dy(CH ₃ COO) ₃ ; the soluble pyridine carboxylic acid is preferably 3-4 pyridine Carboxylic acid, 2-6 pyridine carboxylic acid or 3-5 pyridine carboxylic acid; The alcohol solution is preferably one of methanol, ethanol, propanol or butanol; The alkali solution is preferably NaOH, KOH, ammonia or one of triethylamine. 6. preparation method as claimed in claim 3 is characterized in that, the consumption ratio of the consumption of described copper salt and dysprosium salt and deionized water is 1mmol:1mmol:10-30ml. 7. preparation method as claimed in claim 3, is characterized in that, the mol ratio of described pyridine carboxylic acid and dysprosium salt is 2:1. 8. The preparation method according to claim 3, characterized in that, the stirring adopts mechanical stirring and magnetic stirring, and the rotation speed is 500-1000r/min. 9. The preparation method according to claim 3, characterized in that, the calcination temperature is 800-1000 degrees, and the temperature is kept for 1-3h. 10. The prepared Dy ₂ Cu ₂ O ₅ oxide according to any one of claims 3-8, characterized in that it is used as a photocatalytic material, specifically for catalyzing methylene blue organic dyes.