阅读说明：本技术 一种全光谱响应的氟掺杂铵钨青铜光催化剂及其制备方法 (Full-spectrum response fluorine-doped ammonium tungsten bronze photocatalyst and preparation method thereof ) 是由 高强 吴笑梅 康毅 于 2019-10-16 设计创作，主要内容包括：本发明公开了一种具有全光谱响应的氟掺杂铵钨青铜光催化剂及其制备方法。该方法是将氯化钨和乙酸铵加入正丙醇溶液中,超声溶解,得到A溶液；将氢氟酸溶液加入所述的A溶液中,得到B溶液,在180～220℃条件下反应12～72h；反应产物自然冷却后,洗涤,干燥,得具有全光谱响应的氟掺杂铵钨青铜光催化剂。该催化剂在紫外光照射180min罗丹明B的降解率大于35％,可见光照射120min罗丹明B的的降解率大于90％,近红外光照射180min罗丹明B的的降解率大于80％,且循环五次光催化实验后依然具有高降解率和稳定的活性,能够长期稳定使用。本发明操作简单,原料来源广,成本低且污染物降解率高。(The invention discloses a fluorine-doped ammonium tungsten bronze photocatalyst with full-spectrum response and a preparation method thereof. Adding tungsten chloride and ammonium acetate into an n-propanol solution, and dissolving by ultrasonic to obtain a solution A; adding a hydrofluoric acid solution into the solution A to obtain a solution B, and reacting for 12-72 hours at the temperature of 180-220 ℃; and naturally cooling the reaction product, washing and drying to obtain the fluorine-doped ammonium tungsten bronze photocatalyst with full-spectrum response. The catalyst has the degradation rate of more than 35 percent of rhodamine B in 180min of ultraviolet irradiation, the degradation rate of more than 90 percent of rhodamine B in 120min of visible light irradiation, the degradation rate of more than 80 percent of rhodamine B in 180min of near-infrared irradiation, still has high degradation rate and stable activity after five photocatalytic experiments, and can be stably used for a long time. The method has the advantages of simple operation, wide raw material source, low cost and high pollutant degradation rate.)

1. A preparation method of a fluorine-doped ammonium tungsten bronze photocatalyst with full-spectrum response is characterized by comprising the following steps:

1) adding tungsten chloride and ammonium acetate into an n-propanol solution, and dissolving by ultrasonic to obtain a solution A;

2) adding a hydrofluoric acid solution into the solution A to obtain a solution B, and reacting for 12-72 hours at the temperature of 180-220 ℃;

3) and (3) naturally cooling the reaction product obtained in the step (2), washing and drying to obtain the fluorine-doped ammonium tungsten bronze photocatalyst with full-spectrum response.

2. The method of claim 1, wherein the method comprises the steps of: the molar ratio of ammonium to tungsten atoms in the solution A is 0.33-2: 1.

3. the method of claim 1, wherein the method comprises the steps of: the molar ratio of fluorine atoms to tungsten atoms in the solution B is 3.73-14.9: 1.

4. the method of claim 1, wherein the method comprises the steps of: the step of adding the hydrofluoric acid solution into the solution A is to add the solution A obtained in the step 1) into a reaction kettle with the p-polyphenyl as a lining, and then add the hydrofluoric acid solution.

5. The method of claim 1, wherein the method comprises the steps of: the drying temperature in the step (3) is 40-60 ℃.

6. The method of claim 1, wherein the method comprises the steps of: the washing is respectively washing 3-5 times by deionized water and absolute ethyl alcohol.

7. The method of claim 1, wherein the method comprises the steps of: the concentration of the hydrofluoric acid added in the step (2) is 40 percent by weight.

8. A fluorine-doped ammonium tungsten bronze photocatalyst with full-spectrum response is characterized in that: which is obtained by the production method according to any one of claims 1 to 8; the chemical formula of the fluorine-doped ammonium tungsten bronze photocatalyst is (NH)₄)_xWO_3-yF_y(ii) a Wherein x is more than or equal to 0.25 and less than or equal to 0.33, and y is more than or equal to 0.54 and less than or equal to 0.8.

9. The fluorine doped ammonium tungsten bronze photocatalyst having a full spectrum response of claim 8, wherein: the fluorine-doped ammonium tungsten bronze photocatalyst has a degradation rate of 36-65% in 180min under ultraviolet light, a degradation rate of 87-96% in 120min under visible light, and a degradation rate of 47-83% in 180min under near infrared light.

Technical Field

The invention belongs to the field of environmental purification and green energy utilization, and relates to a full-spectrum corresponding fluorine-doped ammonium tungsten bronze photocatalyst and a preparation method thereof.

Background

The rapid development of the human society in the 21 st century has made great progress in science and technology and humanity, but the problems of resource exhaustion and ecological environment deterioration in the current generation are increasingly highlighted, and a serious challenge is brought to human beings. The sustainable development becomes a necessary road for the contemporary society to realize the sustainabilityTwo major challenges facing development are energy and environmental issues. The photocatalyst is a chemical substance which can change the chemical reaction rate under the irradiation of light and does not participate in the reaction per se. The photocatalyst not only can fully utilize green renewable energy sunlight, but also can be repeatedly utilized without changing the properties of the photocatalyst, and can be used for preparing hydrogen by photolysis to degrade organic and inorganic pollutants in water. The application of the photocatalysis technology in the aspects of environmental purification, microbial sterilization, surface self-cleaning, energy catalysis and the like provides a solution for people. With TiO₂The traditional photocatalyst represented by the general formula has the characteristics of chemical and light corrosion resistance, stable property, no toxicity, high catalytic activity, low price and the like, and is widely applied to the fields of pollutant degradation, water decomposition for hydrogen production, solar cells, pigments and the like. However, the traditional photocatalyst has a large forbidden band width, and can only utilize ultraviolet light and visible light, which only account for 5% and 43% of sunlight respectively. Since 52% of near-infrared light is rarely used, there is a trend toward the development of near-infrared photocatalysts from the viewpoint of the full use of sunlight and the degradation of environmental pollution.

Ammonium Tungsten Bronze (ATB), a non-stoichiometric compound. Blue oxide containing a certain amount of ammonium. With ATB as the main phase and WO_2.90The blue tungsten oxide as the main phase is a high-quality raw material for producing tungsten materials, and because Ammonium Tungsten Bronze (ATB) has high activity and large specific surface area, and is easy to generate physical adsorption and chemical reaction when being mixed with a salt solution, people like to use ATB as a tungsten source when producing doped tungsten powder. Ammonium tungsten bronze is mainly used for heat insulation of architectural glass surfaces because of its excellent absorption properties in the near infrared region.

Tungsten bronze materials are a class of substances that have a strong absorption in the near infrared region. At present, research on tungsten bronze materials focuses on near-infrared shielding performance, and reports on photocatalytic performance of tungsten bronze materials are rare. Chinese patent application 201810200279.6(CN 108558230 a, published 2018.09.21) discloses a method for preparing a high visible light photocatalytic composite material loaded with silver oxide on a tungsten bronze substrate. The degradation rate of the composite material prepared by the application can reach more than 95% within 30 min. However, silver oxide has poor stability, and is reduced into silver by photo-generated electrons in the photocatalysis process, so that the performance of the composite photocatalyst is attenuated.

Chinese patent 201610014726.X (CN 105668632A, published 2016.06.15) discloses a variable-valence metal-catalyzed and doped tungsten bronze A_x-M_yWO₃Firstly, preparing solid colloidal tungstic acid as tungsten source, mixing it with M source, proper solvent and inducer, adding proper quantity of variable valence metal A salt, synthesizing variable valence catalytic and doped tungsten bronze A by thermal reaction_x-M_yWO₃A multifunctional nanoparticle; although the patent synthesizes nanoparticles with excellent near-infrared light shielding performance, the photocatalytic performance of the nanoparticles under ultraviolet light irradiation is poor.

Chinese patent application 201410614449.7 discloses a preparation method of a full-spectrum solar photocatalyst, which uses titanium dioxide as a substrate and loads rare earth oxide, although a composite material with good dispersibility and stable chemical properties can be obtained, the visible light photocatalysis performance of the composite material is poor, and the degradation rate of 20mg/L methyl orange in 120min is only 59% under 500W visible light; the full spectrum of the application refers to ultraviolet light and visible light, does not contain near infrared light photocatalysis performance, and utilizes rare earth metal, so that the raw material is expensive and the cost is high.

The Chinese invention patent 2016104783512 discloses a full-spectrum response type ammonium tungsten bronze-titanium dioxide composite photocatalyst, which is prepared by the following steps: adding 0.1-1.0 g of ammonium tungstate into 20-80 mL of ethylene glycol, and magnetically stirring and dissolving at the temperature of 80-200 ℃; cooling to room temperature, adding 0.1-1.0 g of titanium dioxide serving as a raw material, performing ultrasonic dispersion, and stirring to obtain a suspension; adding 10-80 mL of acetic acid into the suspension and stirring to obtain a mixed liquid, transferring the mixed liquid into a hydrothermal kettle, and carrying out hydrothermal reaction for 10-72 hours at the temperature of 160-240 ℃; and sequentially using deionized water and ethanol to respectively centrifugally wash the precipitate, and drying to obtain the ammonium tungsten bronze-titanium dioxide composite photocatalyst. The photocatalyst has photocatalytic activity under ultraviolet light, visible light and even infrared spectrum, realizes the absorption and utilization of the full spectrum of sunlight, and has wide application prospect in the fields of environmental pollution treatment and purification, environmental protection functional materials and the like. However, the method has complex preparation process and long reaction time, and the prepared sample has poor visible light and near infrared light photocatalytic activity.

The photocatalyst in the prior art can only utilize ultraviolet light and visible light or can only utilize near infrared light with a certain range or a single wavelength mostly, and cannot realize the full utilization of sunlight. Although the composite material widens the spectrum utilization range, the near infrared light has low photocatalytic efficiency.

Disclosure of Invention

The invention aims to provide a full-spectral-response fluorine-doped ammonium tungsten bronze photocatalyst with a simple synthesis process and a preparation method thereof, and solves the problems of narrow spectrum utilization range and low near-infrared light photocatalysis efficiency of the photocatalyst.

The ammonium tungsten bronze is a plasma resonance material with strong absorption in near infrared light, and the near infrared light photocatalysis performance of the ammonium tungsten bronze is limited due to the large forbidden band width. By carrying out certain doping modification on the ammonium tungsten bronze, the material changes the composition structure, improves the photocatalytic performance, realizes the full spectrum utilization of sunlight, and has great significance for the full utilization of renewable energy sources and the practical application of a photocatalyst.

The method takes normal propyl alcohol as a solvent, tungsten chloride and ammonium acetate as a tungsten source and an ammonium source, and hydrofluoric acid is added for fluorine ion doping. Substitution of doped fluorine atoms for WO₆The position of the octahedral lattice oxygen, due to the non-equivalent substitution, generates free electrons. The doped ammonium tungsten bronze not only has strong near infrared light absorption, but also has excellent ultraviolet-visible-near infrared light photocatalysis performance, and the photocatalysis performance is efficient and stable, and can be stably used for a long time. The method has the advantages of simple and easy synthesis steps, wide raw material source and higher practical application value.

The invention can greatly improve the ultraviolet-visible-near infrared photocatalysis performance of the tungsten bronze material, and the promotion mechanism of the photocatalysis for realizing full-spectrum response is as follows: doped fluoride ion is not substituted with equivalenceWO in ammonium tungsten bronze₆The position of lattice oxygen in the octahedron generates a large number of free electrons. On the one hand, these free electrons will be W in ammonium tungsten bronzes⁶⁺Reduction to W⁵⁺High concentration of W⁵⁺Formation of defect energy level (W) below the conduction band of ammonium tungsten bronze⁵⁺) The energy required by electronic transition is reduced, the spectrum utilization range is widened, and the ultraviolet-visible-near infrared photocatalysis performance of the tungsten bronze material is improved; on the other hand, a large amount of free electrons generated by fluorine doping exist near the Fermi level, and due to the existence of the surface electrons, the local plasma resonance effect of the fluorine-doped ammonium tungsten bronze can be excited by near infrared light to form free hot electrons, so that the free hot electrons participate in the photocatalytic degradation process, and the near infrared light photocatalytic performance of the ammonium tungsten bronze material is improved. The ultraviolet-visible-near infrared photocatalysis performance of the tungsten bronze material is greatly improved under the combined action of the two aspects.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a method for synthesizing fluorine-doped ammonium tungsten bronze photocatalyst comprises the following steps:

(1) measuring a certain volume of n-propanol in a beaker, weighing a certain mass of tungsten chloride and ammonium acetate, adding the tungsten chloride and the ammonium acetate into the n-propanol solution, and performing ultrasonic dissolution to obtain a solution A.

(2) Pouring the solution A in the step (1) into a 100mL p-polyphenyl reaction kettle, measuring a certain volume of hydrofluoric acid solution, and adding the hydrofluoric acid solution into the solution A to obtain a solution B. Reacting for 12-72 h at 180-220 ℃.

(3) And (3) naturally cooling, washing the reaction product with deionized water and absolute ethyl alcohol for 3-5 times respectively, and drying to obtain the fluorine-doped ammonium tungsten bronze photocatalyst with full spectral response.

In order to further achieve the purpose of the invention, the volume of the n-propanol solution is preferably 50-80 mL.

Preferably, the molar ratio of ammonium to tungsten in the solution A in the step (1) is 0.33-2: 1.

preferably, the molar ratio of fluorine to tungsten in the solution B in the step (2) is 3.73-14.9: 1.

preferably, the drying temperature in the step (3) is 40-60 ℃.

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

(1) compared with the single application of the existing patent to the tungsten bronze in the near infrared shielding performance, the invention expands the application of the tungsten bronze from the single heat insulation shielding field to the near infrared photocatalysis field by utilizing the characteristic of strong near infrared absorption of the tungsten bronze, and realizes the multifunctional application of the tungsten bronze material.

(2) According to the invention, the tungsten bronze material is doped and modified, the photocatalytic activity of the tungsten bronze material is improved by changing the composition and the structure of the tungsten bronze, and the photocatalytic activity of the tungsten bronze material is improved by using secondary synthesis means such as compounding, noble metal loading and the like instead of improving the photocatalytic activity of the tungsten bronze material by using secondary synthesis means, so that the problem of poor photocatalytic activity of the tungsten bronze material in a near-infrared region is fundamentally solved.

(3) Fluorine-doped ammonium tungsten bronzes still have a plasmon resonance effect and have strong absorption in the near infrared region. The defect that the traditional photocatalyst can only utilize ultraviolet light to catalyze light or can only utilize single near infrared light or near infrared light to catalyze low efficiency is overcome, and the light energy utilization rate and the near infrared light photocatalysis efficiency are improved.

(4) The fluorine-doped ammonium tungsten bronze synthesized by the method still has high degradation rate and stable activity after five times of circulating photocatalytic experiments, and can be stably used for a long time. The invention has simple experimental method, easy repetition of synthesis process and low requirement on experimental equipment. The fluorine-doped ammonium tungsten bronze can fully utilize ultraviolet-visible-near infrared light, has high-efficiency photocatalytic efficiency, and has wide application prospects in the aspects of environmental management and energy utilization.

Drawings

Fig. 1 is XRD patterns of fluorine-doped ammonium tungsten bronze and non-doped fluorine-doped ammonium tungsten bronze photocatalysts prepared in example 1 and comparative example 1.

FIG. 2 is an X-ray photoelectron spectroscopy (XPS) chart of the product obtained in example 1.

Fig. 3 shows near-infrared absorption spectra of fluorine-doped ammonium tungsten bronze and fluorine-free ammonium tungsten bronze prepared in example 1 and comparative example 1.

FIG. 4 is a graph showing the effect of ultraviolet photocatalytic degradation of rhodamine B on fluorine-doped ammonium tungsten bronze and fluorine-free ammonium tungsten bronze prepared in example 1 and comparative example 1.

FIG. 5 is a graph showing the effect of photocatalytic degradation of rhodamine B by visible light of fluorine-doped ammonium tungsten bronze and fluorine-free ammonium tungsten bronze prepared in example 1 and comparative example 1.

FIG. 6 is a graph showing the effect of near-infrared photocatalytic degradation of rhodamine B on fluorine-doped ammonium tungsten bronze and fluorine-free ammonium tungsten bronze prepared in example 1 and comparative example 1.

FIG. 7 is a graph showing the effect of the cycle test on fluorine-doped ammonium tungsten bronze prepared in example 1.

FIG. 8 is a mechanism diagram of the enhancement of near-infrared photocatalytic performance of fluorine-doped ammonium tungsten bronze prepared by the present invention.

Detailed Description

For a better understanding of the present invention, the present invention is further described below with reference to examples and drawings, but embodiments of the present invention are not limited thereto.