CN103611559B - A kind of Bi2WO6-SrTaO2N composite photocatalyst and its preparation method - Google Patents

Abstract

The invention discloses a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst and a preparation method thereof, belonging to the field of inorganic functional materials. The key points of the technical scheme of the present invention are: a Bi ₂ WO _{6 -SrTaO 2} N composite photocatalyst, which is a Bi ₂ WO 6 -SrTaO ₂ N composite photocatalyst formed by compounding Bi ₂ WO ₆ and SrTaO ₂ N powder, Wherein the molar ratio of Bi ₂ WO ₆ to SrTaO ₂ N is 5-15:1. The invention also discloses a preparation method of the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst. Compared with the prior art, the present invention has the following significant advantages: 1. The compounding of Bi ₂ WO ₆ and SrTaO ₂ N can greatly broaden the spectral response range of Bi ₂ WO ₆ , so that Bi ₂ WO ₆ has good absorption in the visible light region , improving the utilization rate of solar energy; 2. The recombination of Bi ₂ WO ₆ and SrTaO ₂ N can effectively reduce the recombination probability of photogenerated electrons and holes, and improve the photocatalytic activity of Bi ₂ WO ₆ ; 3. The Bi ₂ WO 6 of the present invention The preparation method of ₆ -SrTaO ₂ N composite photocatalyst is simple and easy to control.

Description

A kind of Bi2WO6-SrTaO2N composite photocatalyst and its preparation method

technical field

The invention belongs to the technical field of inorganic environment-friendly photocatalytic materials, and in particular relates to a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst and a preparation method thereof.

Background technique

The use of solar photocatalytic decomposition of organic matter has become an important means to solve environmental pollution, but traditional photocatalytic materials such as TiO ₂ and ZnO can only absorb ultraviolet light, and their spectral response range is narrow, which limits their practical application. Therefore, the design of highly responsive visible light catalysts has become one of the major research topics facing photocatalytic science and pollution control. Bi ₂ WO ₆ is a new type of photocatalytic material with visible light response. Its forbidden band width is 2.8 eV, and it can absorb visible light with wavelength less than 442 nm. It is a high-performance visible light photocatalytic material. However, the probability of recombination of holes and electrons generated after photoexcitation of Bi ₂ WO ₆ photocatalysts is high, the quantum effect is low, and the photocatalytic activity is low. Therefore, improving its photon quantum efficiency and photocatalytic activity has become the focus and difficulty of photocatalytic research.

SrTaO ₂ N is a transition metal oxynitride. Since the divalent oxygen element is partially replaced by the less electronegative trivalent nitrogen element, the metal cation is more or less reduced, and the crystal structure changes. SrTaO ₂ N thus exhibits New optical, electrical, magnetic and mechanical properties. Studies have shown that SrTaO ₂ N has a forbidden band width of 2.2 eV and can absorb visible light with a wavelength less than 563 nm. It is a photocatalytic material with visible light responsiveness. In order to improve the photon quantum efficiency of Bi ₂ WO ₆ , it is compounded with SrTaO ₂ N with an ideal band gap, and the energy level difference between the two semiconductors can be used to inject photo-generated interceptors from the energy level of one semiconductor particle to the other. On the energy level of semiconductors, the effective separation of charges is an effective way to improve the solar energy utilization rate and light quantum efficiency of Bi ₂ WO ₆ . The conduction band potential E _CB = 0.46 eV and the valence band potential E _VB = 3.26 eV of the Bi ₂ WO ₆ photocatalyst, while the conduction band potential E _CB = -0.71 eV and the valence band potential E _VB = 1.49 eV of the SrTaO ₂ N photocatalyst . In the Bi ₂ WO ₆ -SrTaO ₂ N compound semiconductor, the conduction band potential of SrTaO ₂ N is more negative, and the photogenerated electrons can easily migrate from the lower energy level SrTaO ₂ N conduction band to the higher energy level Bi ₂ WO ₆ conduction band; At the same time, the valence band potential of Bi ₂ WO ₆ is corrected, and the photogenerated holes can easily migrate from the high-energy Bi ₂ WO ₆ valence band to the low-energy SrTaO ₂ N valence band, thereby improving the separation efficiency of photo-generated charges and extending the Spectral response range _{of Bi2WO6} .

Contents of the invention

The technical problem solved by the invention is to provide a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst with high photon quantum efficiency and good photocatalytic activity.

Another technical problem solved by the present invention is to provide a preparation method of Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst which is simple to operate and easy to control.

_The technical solution of the present invention is: a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst, which is characterized in that the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst formed by compounding Bi ₂ WO 6 and SrTaO ₂ N powder Catalyst, wherein the molar ratio of Bi ₂ WO ₆ to SrTaO ₂ N is 5-15:1.

The preparation method of the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst of the present invention is characterized by comprising the following steps: (1) mixing tantalum pentoxide, strontium carbonate and acetone in a molar ratio of 1:2:15 Add it into an agate mortar and grind it evenly, then spread the sample evenly on a corundum boat, put it into a tubular atmosphere furnace, and calcinate it at 1000°C for 20 hours under an ammonia atmosphere to obtain SrTaO ₂ N powder; (2) Prepare lemon Bismuth acid solution, under the condition of stirring, add the SrTaO ₂ N powder and sodium citrate solution obtained in step (1) into the bismuth citrate solution to obtain a mixed solution A, wherein bismuth citrate and the added SrTaO ₂ N powder The molar ratio of bismuth citrate to added sodium citrate is 10-30:1, and the molar ratio of bismuth citrate to added sodium citrate is 1:1; (3) Prepare sodium tungstate solution, and add sodium tungstate solution to mixed solution A under stirring conditions Mixed solution B was obtained, wherein the molar ratio of bismuth citrate to added sodium tungstate in mixed solution A was 2:1, and then mixed solution B was kept in a water bath at 80°C for 24 hours to obtain a wet gel, wet gel Drying at 110°C to obtain a xerogel; (4) transfer the xerogel obtained in step (3) to a muffle furnace and keep it at 450-600°C for 2-12 hours to obtain Bi ₂ WO ₆ with high catalytic activity - SrTaO ₂ N composite photocatalyst.

The preparation method of the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst of the present invention is characterized in that the molar concentration of the bismuth citrate solution in the step (2) is 0.1-0.5 mol/L. The preparation method of the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst of the present invention is characterized in that the molar concentration of the sodium citrate solution in the step (2) is 0.5 mol/L. The preparation method of the Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst of the present invention is characterized in that the molar concentration of the sodium tungstate solution in the step (3) is 0.1-0.5 mol/L.

Compared with the prior art, the present invention has the following significant advantages: 1. The compounding of Bi ₂ WO ₆ and SrTaO ₂ N can greatly broaden the spectral response range of Bi ₂ WO ₆ , so that Bi ₂ WO ₆ has good absorption in the visible light region , improving the utilization rate of solar energy; 2. The recombination of Bi ₂ WO ₆ and SrTaO ₂ N can effectively reduce the recombination probability of photogenerated electrons and holes, and improve the photocatalytic activity of Bi ₂ WO ₆ ; 3. The Bi ₂ WO 6 of the present invention The preparation method of ₆ -SrTaO ₂ N composite photocatalyst is simple and easy to control.

Description of drawings

Fig. 1 is a comparison curve of the degradation of rhodamine B by the Bi ₂ WO ₆ -SrTaO ₂ N photocatalyst prepared in Example 1 of the present invention and the pure Bi ₂ WO ₆ photocatalyst under the irradiation of a 300W xenon lamp (operating conditions: Quantity: 1 g/L; Concentration of Rhodamine B: 5 mg/L).

Detailed ways:

Below in conjunction with embodiment further describe the present invention. It should be noted that the present invention is not limited to the following examples.

Example 1

(1) Add tantalum pentoxide, strontium carbonate, and acetone with the amounts of 0.0005mol, 0.001mol, and 0.075mol respectively into an agate mortar and grind them evenly, then spread the samples evenly on a corundum boat, and put them into a tube SrTaO ₂ N powder was obtained by calcining at 1000°C for 20 hours in an ammonia atmosphere in an atmosphere furnace;

(2) Prepare 100 mL of bismuth citrate solution with a molar concentration of 0.1 mol/L, prepare 20 mL of a sodium citrate solution with a molar concentration of 0.5 mol/L, and mix the SrTaO ₂ N powder obtained in step (1) and the prepared Add the sodium citrate solution in the bismuth citrate solution to get mixed solution A;

(3) Prepare 50mL of sodium tungstate solution with a molar concentration of 0.1mol/L, add the sodium tungstate solution to mixed solution A under stirring conditions to obtain mixed solution B, and then keep mixed solution B in a water bath at 80°C for 24 Hours to get wet gel, dry the wet gel at 110°C to get dry gel;

(4) Transfer the xerogel obtained in step (3) to a muffle furnace and keep it at 450°C for 12 hours to obtain a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst with high catalytic activity.

Example 2

(1) Add tantalum pentoxide, strontium carbonate, and acetone with the amounts of 0.0005mol, 0.001mol, and 0.075mol respectively into an agate mortar and grind them evenly, then spread the samples evenly on a corundum boat, and put them into a tube SrTaO ₂ N powder was obtained by calcining at 1000°C for 20 hours in an ammonia atmosphere in an atmosphere furnace;

(2) Prepare 100 mL of bismuth citrate solution with a molar concentration of 0.2 mol/L, prepare 40 mL of a sodium citrate solution with a molar concentration of 0.5 mol/L, and mix the SrTaO ₂ N powder obtained in step (1) and The sodium citrate solution prepared is added in the bismuth citrate solution to obtain mixed solution A;

(3) Prepare 50mL of sodium tungstate solution with a molar concentration of 0.2mol/L, add the sodium tungstate solution to the mixed solution A under stirring conditions to obtain the mixed solution B, and then keep the mixed solution B in a water bath at 80°C for 24 Hours to get wet gel, dry the wet gel at 110°C to get dry gel;

(4) Transfer the xerogel obtained in step (3) to a muffle furnace and keep it at 500°C for 6 hours to obtain a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst with high catalytic activity.

Example 3

(1) Add tantalum pentoxide, strontium carbonate, and acetone with the amounts of 0.0005mol, 0.001mol, and 0.075mol respectively into an agate mortar and grind them evenly, then spread the samples evenly on a corundum boat, and put them into a tube SrTaO ₂ N powder was obtained by calcining at 1000°C for 20 hours in an ammonia atmosphere in an atmosphere furnace;

(2) Prepare 60 mL of bismuth citrate solution with a molar concentration of 0.5 mol/L, prepare 60 mL of a sodium citrate solution with a molar concentration of 0.5 mol/L, and mix the SrTaO ₂ N powder obtained in step (1) and the prepared Add the sodium citrate solution in the bismuth citrate solution to get mixed solution A;

(3) Prepare 30mL of sodium tungstate solution with a molar concentration of 0.5mol/L, add the sodium tungstate solution to mixed solution A under stirring conditions to obtain mixed solution B, and then keep mixed solution B in a water bath at 80°C for 24 Hours to get wet gel, dry the wet gel at 110°C to get dry gel;

(4) Transfer the xerogel obtained in step (3) to a muffle furnace and keep it at 600°C for 2 hours to obtain a Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst with high catalytic activity.

The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and that described in the above-mentioned embodiments and the specification only illustrates the principle of the present invention, and the present invention also has various aspects without departing from the scope of the principle of the present invention. Changes and improvements, these changes and improvements all fall within the protection scope of the present invention.

Claims (4)

1. A preparation method of Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst, which is characterized in that it specifically comprises the following steps: (1) mixing tantalum pentoxide, strontium carbonate and acetone in a molar ratio of 1:2:15 Add it into an agate mortar and grind it evenly, then spread the sample evenly on a corundum boat, put it into a tubular atmosphere furnace, and calcinate it at 1000°C for 20 hours under an ammonia atmosphere to obtain SrTaO ₂ N powder; (2) Prepare lemon Bismuth acid solution, under the condition of stirring, add the SrTaO ₂ N powder and sodium citrate solution obtained in step (1) into the bismuth citrate solution to obtain a mixed solution A, wherein bismuth citrate and the added SrTaO ₂ N powder The molar ratio of bismuth citrate to added sodium citrate is 10-30:1, and the molar ratio of bismuth citrate to added sodium citrate is 1:1; (3) Prepare sodium tungstate solution, and add sodium tungstate solution to mixed solution A under stirring conditions Mixed solution B was obtained, wherein the molar ratio of bismuth citrate to added sodium tungstate in mixed solution A was 2:1, and then mixed solution B was kept in a water bath at 80°C for 24 hours to obtain a wet gel, wet gel Drying at 110°C to obtain a xerogel; (4) transfer the xerogel obtained in step (3) to a muffle furnace and keep it at 450-600°C for 2-12 hours to obtain Bi ₂ WO ₆ with high catalytic activity - SrTaO ₂ N composite photocatalyst. 2. The preparation method of Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst according to claim 1, characterized in that the molar concentration of bismuth citrate solution in step (2) is 0.1-0.5 mol/L. 3. The preparation method of Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst according to claim 1, characterized in that the molar concentration of the sodium citrate solution in step (2) is 0.5 mol/L. 4. The preparation method of Bi ₂ WO ₆ -SrTaO ₂ N composite photocatalyst according to claim 1, characterized in that the molar concentration of sodium tungstate solution in step (3) is 0.1-0.5 mol/L.