CN106219606B - A kind of nanometer of flower ball-shaped Ag3VO4Preparation method - Google Patents

Abstract

A kind of nanometer of flower ball-shaped Ag₃VO₄Preparation method, using precipitation assisting alcohol-hydrothermal method synthesis, preparation method includes：Silver nitrate is added to polyvinylpyrrolidone and the ammonium metavanadate (NH of a concentration of 0.1~0.3mol/L₄VO₃) in mixed solution, adjust pH value to after 4~12 with the NaOH solution of 0.2mol/L, 4~12h is heat-treated at 80~180 DEG C.It is washed respectively with distilled water and absolute ethyl alcohol after obtained sediment filtering, and dry in 60~80 DEG C of vacuum drying chamber.Obtained vanadic acid silver powder is mono-crystalline structures, and chemical composition is uniform, and purity is higher, has larger specific surface area, improves the photocatalysis performance of material.

Description

A kind of preparation method of nano flower spherical Ag3VO4

technical field

The invention belongs to the field of preparation of inorganic materials, relates to the preparation and application of semiconductor nanometer materials, in particular to a preparation method of nano flower spherical Ag ₃ VO ₄ .

Background technique

Photocatalytic technology is an emerging technology in the field of energy and environment. Photocatalytic materials represented by TiO ₂ can completely oxidize and decompose organic pollutants in the environment into H ₂ O, CO ₂ and other non-toxic and harmless materials at room temperature. It has the advantages of high efficiency, low cost, and resistance to chemical and photochemical corrosion of the catalyst, so it has attracted more and more attention. Vanadate has been extensively studied because of its good photocatalytic properties. Materials such as BiVO ₄ , InVO ₄ , and FeVO ₄ are widely used in the field of photocatalysis. Lithium vanadate materials have also made great progress in the field of batteries.

The high-energy conduction band of Ag ₃ VO ₄ is formed by the hybridization of Ag 5s and V 3d orbitals, while its low-energy valence band is formed by the hybridization of Ag 4d orbitals and O 2p orbitals. The hybridized valence band structure makes the energy levels more active, resulting in a monoclinic bandgap width <2.7eV. This structural feature makes silver vanadate have a wide response range to visible light, and has potential application prospects in the field of photocatalysis.

At present, the morphology of silver vanadate prepared by hydrothermal method, microwave hydrothermal method and other methods proposed at home and abroad includes: granular, square, fibrous and so on. China Invention Announcement Patent No. 201310257173.7 discloses a silver vanadate nanofiber photocatalyst, which is prepared by electrospinning, but has high requirements for moisture and other technical difficulties. No. 201210531539.0 discloses a rod-shaped silver vanadate nano-photocatalyst. The double-injection precipitation method is used to prepare rod-shaped silver vanadate crystallites, but the technology is difficult and requires high storage conditions for the prepared product. No. 201310287983.7 discloses a method for preparing silver vanadate nanowires, but the reaction period is long. CTAB-assisted hydrothermal synthesis of silvervanadates and their photocatalytic characterization. Chao-Ming Huang et al. used CTAB as a surfactant to prepare a mixed phase of Ag ₃ VO ₄ and Ag ₄ V ₂ O ₇ by hydrothermal combined heat treatment. The product purity It is not high, and the size is large. At present, there are few preparation methods of silver vanadate with special morphology, so the research on silver vanadate with special morphology is of great significance.

Contents of the invention

The present invention aims at the deficiencies of the above-mentioned prior art, and proposes a preparation method of nano-flower spherical Ag ₃ VO ₄ , the method has mild reaction conditions, simple operation, can be repeatedly prepared in large quantities, and the prepared silver vanadate product has high purity and excellent properties. Stablize.

In order to achieve the above object, the present invention adopts the following technical solutions.

A preparation method of nano flower spherical Ag ₃ VO ₄ , comprising the following steps:

(1) Polyvinylpyrrolidone is added to an aqueous ammonium metavanadate solution, and stirred evenly to obtain a mixed solution A;

(2) Add the silver nitrate solution dropwise into the mixed solution A, and stir for 1-3 hours to obtain the mixed solution B;

(3) After adjusting the pH value of the mixed solution to 4-12, conduct a hydrothermal reaction at 80-180°C for 4-12 hours, filter the reaction solution to obtain a precipitate, wash and dry the precipitate to obtain Ag ₃ VO ₄ in nano flower shape .

The further improvement of the present invention is that the concentration of ammonium metavanadate aqueous solution is 0.1～0.3mol/L in the step (1), and the consumption ratio of polyvinylpyrrolidone and ammonium metavanadate aqueous solution is (0.01～0.04) g: (20～ 60) mL.

A further improvement of the present invention lies in that the stirring in step (1) is carried out at 40-100° C., and the stirring time is 1-3 hours.

The further improvement of the present invention is that the concentration of the silver nitrate solution described in step (2) is 0.1～0.3mol/L, and the consumption ratio of silver nitrate solution and ammonium metavanadate aqueous solution is (20～60) mL: (10～ 60) mL.

The further improvement of the present invention lies in that step (3) uses 0.1-0.3 mol/L NaOH solution to adjust the pH value of the mixed solution B.

The further improvement of the present invention lies in adjusting the pH value of the mixed solution to 4-12, stirring for 1-8 hours, and then carrying out hydrothermal reaction.

A further improvement of the present invention is that the hydrothermal reaction described in step (3) is carried out in a high-pressure reactor.

A further improvement of the present invention lies in that the washing described in step (3) is to wash the precipitate with distilled water and ethanol.

A further improvement of the present invention is that the drying described in step (3) is carried out at 40-80°C.

Compared with prior art, the present invention can obtain following beneficial effect:

(1) The precipitation-assisted hydrothermal method adopted in the present invention uses _NH4VO3 as the vanadium source, _AgNO3 as the silver source, _PVP as the surfactant, and adjusts the pH value of the solution with NaOH aqueous solution. Under the hydrothermal reaction, the flower-shaped silver vanadate with good photocatalytic performance and uniform size was prepared.

(2) The present invention synthesizes silver vanadate by a wet chemical method, and realizes the mixing of Ag, V, and O at the molecular level. The product is uniform in size and has a single crystal structure.

(3) The precipitation-assisted hydrothermal process of the present invention has short process, simple process, stable product quality and uniform appearance, and is easy to realize industrialization.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the silver vanadate prepared under the condition of embodiment 3 of the present invention.

Fig. 2 is the scanning electron microscope figure of the silver vanadate prepared under the condition of embodiment 3 of the present invention, wherein, figure (a) is the scanning figure of the catalyst prepared without adding PVP, figure (b) is PVP as surfactant Scans of prepared catalysts.

Fig. 3 is the degradation curve of rhodamine B under visible light irradiation of silver vanadate prepared under the conditions of Example 3 of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

Example 1

(1) Add 0.01 g of polyvinylpyrrolidone (PVP) to 20 mL of 0.1 mol/L ammonium metavanadate (NH ₄ VO ₃ ) aqueous solution, stir magnetically at 90° C. for 1 h, and cool to room temperature to obtain mixed solution A.

(2) 60 mL of 0.3 mol/L silver nitrate (AgNO ₃ ) solution was added dropwise into the mixed solution A, and magnetically stirred for 1 hour to obtain the mixed solution B.

(3) Use 0.1mol/L NaOH solution to adjust the pH value of the mixed solution B to 12, then magnetically stir for 3 hours, and conduct a hydrothermal reaction at 180°C for 4 hours. After the reaction, filter the reaction solution to obtain a precipitate, and filter the obtained precipitate Afterwards, they were centrifuged and washed with distilled water and ethanol respectively, and dried in an oven at 70°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

Example 2

(1) Add 0.02g of polyvinylpyrrolidone (PVP) to 20mL of 0.1mol/L ammonium metavanadate (NH ₄ VO ₃ ) aqueous solution, stir magnetically at 80°C for 1 hour, and cool to room temperature to obtain mixed solution A.

(2) 60 mL of 0.3 mol/L silver nitrate (AgNO ₃ ) solution was added dropwise into the mixed solution A, and magnetically stirred for 1 hour to obtain the mixed solution B.

(3) Use 0.2 mol/L NaOH solution to adjust the pH value of the mixed solution B to 10, then magnetically stir for 3 hours, and conduct a hydrothermal reaction at 150°C for 6 hours. After the reaction, filter the reaction solution to obtain a precipitate, and filter the obtained precipitate Afterwards, they were centrifuged and washed with distilled water and ethanol respectively, and dried in an oven at 70°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

Example 3

(1) Add 0.03g of polyvinylpyrrolidone (PVP) to 20mL of 0.1mol/L ammonium metavanadate (NH ₄ VO ₃ ) aqueous solution, stir magnetically at 60°C for 1 hour, and cool to room temperature to obtain mixed solution A.

(2) 60 mL of 0.3 mol/L silver nitrate (AgNO ₃ ) solution was added dropwise into the mixed solution A, and magnetically stirred for 1 hour to obtain the mixed solution B.

(3) Use 0.3 mol/L NaOH solution to adjust the pH value of the mixed solution B to 7, then magnetically stir for 3 hours, and conduct a hydrothermal reaction at 120°C for 8 hours. After the reaction, filter the precipitate obtained by filtering the reaction solution and use Washed with distilled water and ethanol by centrifugation, and dried in an oven at 70°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

Referring to Figure 1, through the XRD diffraction pattern, it can be clearly seen that the Ag ₃ VO ₄ prepared by the present invention has a pure phase single crystal structure;

Referring to Figure 2, it can be seen from the scanning electron microscope photos of Figure 2(a) and Figure 2(b) that the curd-shaped flakes have a thickness of 10nm-20nm, self-assembled into a curd-like shape, and the diameter of the curd is 2-5μm;

Referring to Fig. 3, put 0.05g of the powder into 50mL Rhodamine B solution (Rhodamine B concentration 10mg/L), under the condition of visible light irradiation, the degradation rate of Rhodamine B can reach more than 80% after 4 hours of reaction.

Example 4

(1) Add 0.04g polyvinylpyrrolidone (PVP) to 20mL 0.1mol/L ammonium metavanadate (NH ₄ VO ₃ ) aqueous solution, stir magnetically at 40°C for 1 hour, and cool to room temperature to obtain a mixed solution A.

(2) 60 mL of 0.3 mol/L silver nitrate (AgNO ₃ ) solution was added dropwise into the mixed solution A, and magnetically stirred for 1 hour to obtain the mixed solution B.

(3) Use 0.2 mol/L NaOH solution to adjust the pH value of the mixed solution B to 4, then magnetically stir for 3 hours, and conduct a hydrothermal reaction at 100°C for 10 hours. After the reaction, filter the reaction solution to obtain a precipitate, and filter the obtained precipitate Afterwards, they were centrifuged and washed with distilled water and ethanol respectively, and dried in an oven at 70°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

Example 5

(1) Add polyvinylpyrrolidone to ammonium metavanadate aqueous solution, stir at 40°C for 3 hours to obtain mixed solution A; wherein, the concentration of ammonium metavanadate aqueous solution is 0.2mol/L, polyvinylpyrrolidone and metavanadate The dosage ratio of ammonium aqueous solution is 0.02g:40mL.

(2) silver nitrate solution is added dropwise in mixed solution A, stirs down 2h, obtains mixed solution B; Wherein, the concentration of silver nitrate solution is 0.1mol/L, and the consumption ratio of silver nitrate solution and ammonium metavanadate aqueous solution is 20mL: 40mL.

(3) Use 0.1mol/L NaOH solution to adjust the pH value of the mixed solution to 8, then stir for 1h, then carry out hydrothermal reaction in a high-pressure reactor at 80°C for 12h, filter the reaction solution to obtain a precipitate, and the precipitate is washed with distilled water and Washed with ethanol and dried at 40°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

Example 6

(1) Add polyvinylpyrrolidone to ammonium metavanadate aqueous solution, stir at 100°C for 1 hour to obtain mixed solution A; wherein, the concentration of ammonium metavanadate aqueous solution is 0.3mol/L, polyvinylpyrrolidone and metavanadate The dosage ratio of the ammonium aqueous solution is 0.04g:60mL.

(2) silver nitrate solution is added dropwise in mixed solution A, stirs down 3h, obtains mixed solution B; Wherein, the concentration of silver nitrate solution is 0.2mol/L, and the consumption ratio of silver nitrate solution and ammonium metavanadate aqueous solution is 40mL: 60mL.

(3) Use 0.3mol/L NaOH solution to adjust the pH value of the mixed solution to 5 and then stir for 8 hours, then carry out hydrothermal reaction in a high-pressure reactor at 140°C for 7 hours, filter the reaction solution to obtain a precipitate, and the precipitate is washed with distilled water and Washed with ethanol and dried at 80°C to obtain spherical Ag ₃ VO ₄ nanoflowers.

The flower spherical silver vanadate nanomaterial photocatalyst prepared by the invention has a monoclinic crystal phase, and the composition expression of the particle is Ag ₃ VO ₄ . The thickness of the nanosheet is 10nm-20nm, self-assembled into a curd shape, and the diameter of the curd is 2-5μm.

The silver vanadate is pure phase silver vanadate obtained under different pH conditions. Flower-shaped silver vanadate nanomaterials were synthesized by a precipitation-assisted hydrothermal method. The chemical composition is uniform, the purity is high, and the specific surface area is large, which improves the photocatalytic performance of the material.

Claims (5)

1. a kind of nanometer of flower ball-shaped Ag₃VO₄Preparation method, which is characterized in that include the following steps：

(1) polyvinylpyrrolidone is added in ammonium metavanadate aqueous solution, stirred evenly, obtain mixed solution A；

(2) silver nitrate solution is added drop-wise in mixed solution A, stirs lower 1~3h, obtain mixed solution B；

(3) mixed solution B pH value is adjusted to after 4~12, stirs 1~8h, 4~12h of hydro-thermal reaction is carried out at 80~180 DEG C Afterwards, precipitation is obtained by filtration in reaction solution, precipitation is washed, dry, obtains a nanometer flower ball-shaped Ag₃VO₄；

A concentration of 0.1~0.3mol/L of ammonium metavanadate aqueous solution in step (1)；

Stirring carries out at 40~100 DEG C in step (1), and the time stirred is 1~3h；

The amount ratio of polyvinylpyrrolidone and ammonium metavanadate aqueous solution is (0.01~0.04) g：(20~60) mL；

A concentration of 0.1~0.3mol/L of silver nitrate solution described in step (2), silver nitrate solution and ammonium metavanadate aqueous solution Amount ratio is (20~60) mL：(10~60) mL.

2. a kind of nanometer of flower ball-shaped Ag according to claim 1₃VO₄Preparation method, which is characterized in that step (3) use The NaOH solution of 0.1~0.3mol/L adjusts the pH value of mixed solution B.

3. a kind of nanometer of flower ball-shaped Ag according to claim 1₃VO₄Preparation method, which is characterized in that step (3) is described Hydro-thermal reaction be to be carried out in autoclave.

4. a kind of nanometer of flower ball-shaped Ag according to claim 1₃VO₄Preparation method, which is characterized in that step (3) is described Washing be to wash precipitation with distilled water and ethyl alcohol.

5. a kind of nanometer of flower ball-shaped Ag according to claim 1₃VO₄Preparation method, which is characterized in that step (3) is described Drying be to be carried out at 40~80 DEG C.