阅读说明：本技术 一种铬酸银基上转换复合光催化剂的制备方法及其应用 (Preparation method and application of silver chromate based up-conversion composite photocatalyst ) 是由 杨凯 张开莲 余长林 李笑笑 穆萍 禹振振 李文强 黄健 刘子龙 于 2019-09-25 设计创作，主要内容包括：本发明涉及一种铬酸银基上转换复合光催化剂的制备方法及其应用,该方法包括：配置RE(NO<Sub>3</Sub>)<Sub>3</Sub>溶液、EDTA-2Na溶液以及NH<Sub>4</Sub>F溶液,将EDTA-2Na溶液滴加到RE(NO<Sub>3</Sub>)<Sub>3</Sub>溶液中以得到第一混合液,将NH<Sub>4</Sub>F溶液滴加至第一混合溶液中以得到第二混合溶液,调节pH值后转移至反应釜中反应第一预设时间,冷却至室温后抽滤、洗涤干燥得到上转换材料；配置AgNO<Sub>3</Sub>溶液以及K<Sub>2</Sub>Cr<Sub>2</Sub>O<Sub>7</Sub>溶液,将制得的上转换材料加入至AgNO<Sub>3</Sub>溶液中得到第三混合溶液,滴入K<Sub>2</Sub>Cr<Sub>2</Sub>O<Sub>7</Sub>溶液得到第四混合溶液,抽滤洗涤干燥得到复合型Ag<Sub>2</Sub>CrO<Sub>4</Sub>基光催化剂。本发明制备得到的铬酸银基上转换复合光催化剂,具有良好的污染物分解能力。(The invention relates to a preparation method and application of a silver chromate based up-conversion composite photocatalyst, wherein the method comprises the following steps: configuring RE (NO) 3 ) 3 Solution, EDTA-2Na solution, and NH 4 F solution, EDTA-2Na solution is added to RE (NO) dropwise 3 ) 3 Adding NH to the solution to obtain a first mixed solution 4 Dropwise adding the solution F into the first mixed solution to obtain a second mixed solution, adjusting the pH value, transferring the solution F into a reaction kettle, reacting for a first preset time, cooling to room temperature, performing suction filtration, washing and drying to obtain an up-conversion material; preparation of AgNO 3 Solution and K 2 Cr 2 O 7 Solution of the prepared upconverter material to AgNO 3 Adding K to obtain a third mixed solution 2 Cr 2 O 7 Obtaining a fourth mixed solution from the solution, filtering, washing and drying to obtain the composite Ag 2 CrO 4 A base photocatalyst. The silver chromate based up-conversion composite photocatalyst prepared by the invention has good pollutant decomposition capability.)

1. A preparation method of a silver chromate based up-conversion composite photocatalyst is characterized by comprising the following steps:

preparing an up-conversion material:

are respectively configured to obtain RE (NO)₃)₃Solution, EDTA-2Na salt solution and NH₄F solution, dropwise adding the EDTA-2Na salt solution to the RE (NO) under the condition of magnetic stirring₃)₃Adding the solution to obtain a first mixed solution, stirring the first mixed solution again, and adding the NH₄Dropwise adding the solution F into the first mixed solution to obtain a second mixed solution, adjusting the second mixed solution to a preset pH value by using a dilute nitric acid solution with a first concentration under a stirring condition, transferring the second mixed solution into a polytetrafluoroethylene reaction kettle, controlling the second mixed solution to react for a first preset time at a first preset temperature, performing suction filtration and washing on the second mixed solution after the second mixed solution is cooled to room temperature, and drying the second mixed solution at a second preset temperature for a second preset time to obtain the up-conversion material;

preparation of Ag₂CrO₄Basically, converting the composite photocatalyst:

respectively preparing to obtain AgNO₃Solution and K₂Cr₂O₇A solution of the prepared upconverter material added to the AgNO₃Adding into the solution to obtain a third mixed solution, magnetically stirring, and adding dropwise K₂Cr₂O₇Obtaining a fourth mixed solution by the solution, finally carrying out suction filtration and washing on the fourth mixed solution, and then drying to obtain the Ag₂CrO₄And basically converting the composite photocatalyst.

2. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the RE (NO) is₃)₃The preparation method of the solution comprises the following steps: a first molar amount of RE (NO)₃)₃Dissolving in a first preset volume of deionized water, and stirring to obtain RE: (NO₃)₃Solution of RE (NO)₃)₃Y (NO) contained in solution₃)₃、Yb(NO₃)₃And Er (NO)₃)₃The corresponding molar ratio was 76:22: 1.5;

the preparation method of the EDTA-2Na salt solution comprises the following steps: dissolving EDTA-2Na salt with a second molar weight into deionized water with a second preset volume, and stirring to obtain the EDTA-2Na salt solution;

NH₄the preparation method of the F solution comprises the following steps: adding a third molar amount of NH₄F is dissolved in deionized water with a third preset volume, and NH is obtained after stirring₄And F, solution.

3. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 2, wherein the first molar amount is 1.73-6.89 mmol, the first preset volume is 10-20 ml, the second molar amount is 1.73-6.89 mmol, the second preset volume is 15-30 ml, the third molar amount is 9.134-36.534 mmol, and the third preset volume is 15-30 ml.

4. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the AgNO is₃The preparation method of the solution comprises the following steps: 0.3-3 mmol of AgNO₃Dissolving the AgNO in 4-40 ml of deionized water, and stirring to obtain the AgNO₃A solution;

said K₂Cr₂O₇The preparation method of the solution comprises the following steps: adding 0.075-0.75 mmol of K₂Cr₂O₇Dissolving the K in 4-40 ml of deionized water, and stirring to obtain the K₂Cr₂O₇And (3) solution.

5. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the first concentration is 0.5-1.5 mol/L, and the predetermined pH value is 2-3.

6. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the first preset temperature is 180 ℃ and the first preset time is 12 hours, the second preset temperature is 60 ℃ and the second preset time is 10 hours.

7. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the NH is added₄And in the step of dropwise adding the solution F into the first mixed solution to obtain a second mixed solution, the first mixed solution is colorless, and the second mixed solution is milky white.

8. The method for preparing the silver chromate-based up-conversion composite photocatalyst as claimed in claim 1, wherein the prepared up-conversion material is added to AgNO₃In the step of dissolving to obtain a third mixed solution, the color of the third mixed solution is dark red.

9. The method for preparing the silver chromate based up-conversion composite photocatalyst as claimed in claim 1, wherein the up-conversion material is NaYF₄Yb and Er, the composite silver chromate based photocatalyst is NaYF₄:Yb,Er/Ag₂CrO₄A catalyst.

10. Use of a silver chromate based up-conversion composite photocatalyst prepared by the preparation method of any one of claims 1 to 9 for removing at least one of methyl blue, methyl orange, methylene blue, or rhodamine B from contaminants or for photocatalytic oxidation of anhydrous ethanol to produce hydrogen peroxide.

Technical Field

The invention relates to the technical field of photocatalyst preparation, in particular to a preparation method and application of a silver chromate based up-conversion composite photocatalyst.

Background

With the rapid development of economy and the continuous progress of science and technology, the problems of environmental pollution and energy shortage are becoming more and more prominent in recent years. At present, the pollution problem is urgently needed to be treated by a green pollution-free environment-friendly technology. The photocatalytic technology is a common pollutant degradation mode, and is increasingly concerned by people because the photocatalytic technology can effectively degrade organic pollutants such as rhodamine B, methyl orange, phenol and the like. The photocatalytic degradation technology is to absorb external sunlight to perform a series of oxidation-reduction reactions so as to achieve the effect of degrading pollutants. In addition, the photocatalysis technology can also utilize solar photocatalysis to crack water to generate hydrogen energy, and is expected to solve the energy crisis problem. TiO 2₂The semiconductor photocatalyst which is the earliest researched by researchers has the advantages of high stability, low price and the like, so that the semiconductor photocatalyst arouses the interest of broad scholars. However, TiO₂Has wide band gap, only absorbs ultraviolet light, and in sunlight, contains 5 percent of ultraviolet light, 46 percent of visible light and 49 percent of near infrared light,thus TiO₂The utilization rate of sunlight is limited. Based on this, there is an urgent need to find other semiconductors that respond to visible light to improve the utilization of sunlight.

Ag₂CrO₄Semiconductors have properties such as narrow band gap (1.7 eV), ability to absorb visible light, and benefit for electronic transition, and are widely used in the field of modified wide band gap semiconductors. Ag₂CrO₄The semiconductor is combined with other semiconductors to form a Z-type heterojunction, so that the absorption edge of sunlight can be widened, and the separation of photo-generated electron hole pairs is facilitated, thereby being beneficial to the improvement of photocatalytic activity. However, it is still a difficult problem for wide band gap semiconductors to improve their efficiency of sunlight. Therefore, if there is a converter that converts light of a long wavelength into light of a short wavelength, the converter is used to promote application of a wide band gap semiconductor to a photocatalytic system, and to expand the application of the wide band gap semiconductor to the photocatalytic field, and therefore, the converter has a significant application significance. The upconversion material attracts attention of broad researchers because it can convert light with lower energy into light with higher energy through energy transfer and transition process to excite semiconductor to generate photo-generated electrons under excitation of incident light such as 980 nm.

However, the prior art lacks the ability to incorporate up-converting materials with Ag₂CrO₄The report of semiconductor forming heterojunction photocatalyst, whose degradation treatment of contaminants is in a blank state.

Disclosure of Invention

Based on this, the present invention aims to solve the problem of the lack of a method for combining an upconversion material with Ag in the prior art₂CrO₄The semiconductor forms a heterojunction photocatalyst to degrade pollutants.

The invention provides a preparation method of a silver chromate based up-conversion composite photocatalyst, wherein the method comprises the following steps:

preparing an up-conversion material:

are respectively configured to obtain RE (NO)₃)₃Solution, EDTA-2Na salt solution and NH₄F solution, the EDTA-2Na salt solution is stirred under the condition of magnetic forceIs added dropwise to the RE (NO)₃)₃Adding the solution to obtain a first mixed solution, stirring the first mixed solution again, and adding the NH₄Dropwise adding the solution F into the first mixed solution to obtain a second mixed solution, adjusting the second mixed solution to a preset pH value by using a dilute nitric acid solution with a first concentration under a stirring condition, transferring the second mixed solution into a polytetrafluoroethylene reaction kettle, controlling the second mixed solution to react for a first preset time at a first preset temperature, performing suction filtration and washing on the second mixed solution after the second mixed solution is cooled to room temperature, and drying the second mixed solution at a second preset temperature for a second preset time to obtain the up-conversion material;

preparing a silver chromate based up-conversion composite photocatalyst:

respectively preparing to obtain AgNO₃Solution and K₂Cr₂O₇A solution of the prepared upconverter material added to the AgNO₃Adding into the solution to obtain a third mixed solution, magnetically stirring, and adding dropwise K₂Cr₂O₇And finally, carrying out suction filtration and washing on the fourth mixed solution, and then drying to obtain the silver chromate-based up-conversion composite photocatalyst.

The preparation method of the silver chromate based up-conversion composite photocatalyst provided by the invention comprises the steps of firstly respectively preparing RE (NO)₃)₃Solution, EDTA-2Na salt solution and NH₄F solution, then according to RE (NO)₃)₃Solution, EDTA-2Na salt solution and NH₄Preparing an upconversion material by using the F solution, and adding the prepared upconversion material into AgNO₃Adding K into the solution after magnetic stirring₂Cr₂O₇The solution is finally filtered, washed and dried by suction to obtain Ag₂CrO₄And basically converting the composite photocatalyst. The composite Ag prepared by the invention₂CrO₄The basic conversion composite photocatalyst has good elimination effect on methyl blue, methyl orange, methylene blue and rhodamine B in pollutants, and can be used for producing hydrogen peroxide by photocatalytic oxidation of absolute ethyl alcohol.

In addition, the preparation method of the silver chromate based up-conversion composite photocatalyst provided by the invention can also have the following additional technical characteristics:

the preparation method of the silver chromate based up-conversion composite photocatalyst comprises the step of preparing the RE (NO)₃)₃The preparation method of the solution comprises the following steps: a first molar amount of RE (NO)₃)₃Dissolving in deionized water with a first preset volume, and stirring to obtain RE (NO)₃)₃Solution of RE (NO)₃)₃Y (NO) contained in solution₃)₃、Yb(NO₃)₃And Er (NO)₃)₃The corresponding molar ratio was 76:22: 1.5;

the preparation method of the EDTA-2Na salt solution comprises the following steps: dissolving EDTA-2Na salt with a second molar weight into deionized water with a second preset volume, and stirring to obtain the EDTA-2Na salt solution;

NH₄the preparation method of the F solution comprises the following steps: adding a third molar amount of NH₄F is dissolved in deionized water with a third preset volume, and NH is obtained after stirring₄And F, solution.

The preparation method of the silver chromate based up-conversion composite photocatalyst comprises the steps that the first molar weight is 1.73-6.89 mmol, the first preset volume is 10-20 ml, the second molar weight is 1.73-6.89 mmol, the second preset volume is 15-30 ml, the third molar weight is 9.134-36.534 mmol, and the third preset volume is 15-30 ml.

The preparation method of the silver chromate based up-conversion composite photocatalyst comprises the step of preparing AgNO₃The preparation method of the solution comprises the following steps: 0.3-3 mmol of AgNO₃Dissolving the AgNO in 4-40 ml of deionized water, and stirring to obtain the AgNO₃A solution;

said K₂Cr₂O₇The preparation method of the solution comprises the following steps: adding 0.075-0.75 mmol of K₂Cr₂O₇Dissolving the K in 4-40 ml of deionized water, and stirring to obtain the K₂Cr₂O₇And (3) solution.

The preparation method of the silver chromate based up-conversion composite photocatalyst comprises the steps that the first concentration is 0.5-1.5 mol/L, and the preset pH value is 2-3.

The preparation method of the silver chromate-based up-conversion composite photocatalyst comprises the steps that the first preset temperature is 180 ℃, the first preset time is 12 hours, the second preset temperature is 60 ℃, and the second preset time is 10 hours.

The preparation method of the silver chromate based up-conversion composite photocatalyst comprises the step of adding the NH₄And in the step of dropwise adding the solution F into the first mixed solution to obtain a second mixed solution, the first mixed solution is colorless, and the second mixed solution is milky white.

The preparation method of the silver chromate-based up-conversion composite photocatalyst comprises the step of adding the prepared up-conversion material into AgNO₃In the step of dissolving to obtain a third mixed solution, the color of the third mixed solution is dark red.

The preparation method of the silver chromate based up-conversion composite photocatalyst comprises the step of preparing an up-conversion material NaYF₄Yb and Er, the composite silver chromate based photocatalyst is NaYF₄:Yb,Er/Ag₂CrO₄A catalyst.

The invention also provides application of the silver chromate-based up-conversion composite photocatalyst, wherein the composite silver chromate-based photocatalyst prepared by the preparation method is used for eliminating at least one of methyl blue, methyl orange, methylene blue or rhodamine B in pollutants or is used for photocatalytic oxidation of absolute ethyl alcohol to produce hydrogen peroxide.

Additional features and advantages of the disclosure will be set forth in the description which follows, or in part may be learned by the practice of the above-described techniques of the disclosure, or may be learned by practice of the disclosure.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a graph showing a comparison of conversion rates of hydrogen peroxide generated by photocatalytic oxidation of absolute ethanol under dark conditions, catalyst-free conditions, pure silver chromate conditions, and various silver chromate-based composite photocatalysts with different mass percentages, according to an embodiment of the present invention;

FIG. 2 is a graph showing the comparison of the catalytic degradation performance of methyl orange under dark conditions, catalytic conditions of an upconversion material, pure silver chromate, and various composite silver chromate-based photocatalysts with different mass percentages, according to an embodiment of the present invention (where NYF and AC correspond to NaYF respectively₄Yb, Er and Ag₂CrO₄)；

FIG. 3 shows pure Ag₂CrO₄Pure up-conversion material and composite Ag prepared from up-conversion materials with different mass percentages₂CrO₄XRD pattern corresponding to base photocatalyst;

FIG. 4 shows pure Ag₂CrO₄Scanning Electron Micrographs (SEM) of the catalyst;

FIG. 5 is a 20% NaYF₄:Yb,Er/Ag₂CrO₄Scanning Electron Micrographs (SEM) of the catalyst;

FIG. 6 is a 20% NaYF₄:Yb,Er/Ag₂CrO₄Transmission Electron Micrographs (TEM) of the catalyst;

FIG. 7 is a 20% NaYF₄:Yb,Er/Ag₂CrO₄High Resolution Transmission Electron Micrographs (HRTEM) of the catalyst;

FIG. 8 shows pure Ag₂CrO₄And composite Ag prepared from up-conversion materials with different mass percentages₂CrO₄Ultraviolet diffuse reflectance patterns corresponding to the base photocatalysts;

FIG. 9 shows the upconverting material and 20% NaYF₄:Yb,Er/Ag₂CrO₄Photoluminescence profile of the catalyst.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.