阅读说明：本技术 一步合成Z-Scheme AgBr/β-Ag2WO4光催化剂的方法 (one-step synthesis of Z-Scheme AgBr/beta-Ag2WO4Method for preparing photocatalyst ) 是由 刘孝恒 殷鸿飞 于 2019-08-16 设计创作，主要内容包括：本发明公开了一步合成可见光响应的直接Z-Scheme AgBr/β-Ag_2WO_4光催化剂的方法。该光催化剂在微观上为纳米颗粒和微米棒构成的复合结构,在光催化降解罗丹明B方面表现出良好的催化活性。(The invention discloses a direct Z-Scheme AgBr/beta-Ag for one-step synthesis of visible light response 2 WO 4 A method of photocatalyst. The photocatalyst is a composite structure formed by nano particles and micron rods on the microcosmic aspect, and shows good catalytic activity in the aspect of photocatalytic degradation of rhodamine B.)

1.Z-Scheme AgBr/β-Ag₂WO₄The composite material is characterized in that the AgBr/beta-Ag₂WO₄The composite material is prepared from AgBr and beta-Ag₂WO₄Prepared at room temperature in a mass ratio of 5-30%.

2. One-step synthesis of Z-Scheme AgBr/beta-Ag₂WO₄A method of photocatalyst, comprisingThe following steps:

firstly, adding cetyl trimethyl ammonium bromide into a silver nitrate solution, and magnetically stirring for 2 hours to form a mixed solution in which AgBr sol and silver ions coexist;

secondly, dissolving sodium tungstate in water with the same volume as the silver nitrate solution in the first step;

Step three, dropwise adding the solution obtained in the step one into the solution obtained in the step two, and magnetically stirring for 6 hours at room temperature in a dark condition;

fourthly, centrifugally washing and drying the sample obtained in the third step to prepare AgBr/beta-Ag₂WO₄A composite material.

3. The method of claim 2, wherein in the first step, the concentration of silver nitrate is 20mM and the concentration of cetyltrimethylammonium bromide is 7.5% -27% of the concentration of silver nitrate.

4. the method of claim 2, wherein in the second step, the concentration of the sodium tungstate solution is 0.5 times the concentration of the silver nitrate solution in the first step.

5. The method of claim 2, wherein in the fourth step, the rotation speed of the centrifuge is 9000r/min, the centrifugation time is 3min, and the oven temperature is 60 ℃.

Technical Field

the invention relates to a one-step synthesis method of Z-Scheme AgBr/beta-Ag₂WO₄A method of photocatalyst, belonging to the field of nano material preparation.

background

Environmental pollution and energy shortage are two major focus problems in the world at present, the photocatalysis technology is an ideal technology for solving the energy shortage and the environmental problem, solar energy is converted into chemical energy by utilizing a semiconductor photocatalysis material, beneficial products including hydrogen, hydrocarbon and the like are obtained, pollutants, bacteria and the like are removed, and the semiconductor photocatalysis technology is widely concerned.

Silver tungstate (Ag)₂WO₄) Due to the fact that the forbidden band width of the ultraviolet light-emitting diode is large, the ultraviolet light-emitting diode has strong response to ultraviolet light and weak response to visible light, and the ultraviolet light only accounts for a very low proportion (-5%) in the solar spectrum, and the utilization of the ultraviolet light-emitting diode to the solar spectrum is greatly limited. In addition, silver tungstate (Ag)₂WO₄) Has three crystal forms (alpha-, beta-, and gamma-), and researches show that the beta-Ag₂WO₄Specific alpha-Ag₂WO₄has higher photocatalytic performance, however, most of the current Ag₂WO₄All focused on alpha-Ag₂WO₄. To raise Ag₂WO₄the photocatalytic performance of (A) Ag/AgBr/Ag was prepared by ion exchange method using KBr as Br source by Shijie Li et al₂WO₄The photocatalyst is used for degrading RhB and tetracycline hydrochloride and shows purer Ag than pure Ag₂WO₄High-efficiency photocatalytic performance [ Shijie Li, et al. (2018) ]construction of a novel tertiary Ag/AgBr/Ag₂WO₄composite for efficient photocatalytic removal of Rhodamine B dye and tetracycline hydrochlorideantibiotic”Materials Letters 224:29-32.]. Jingking Li et al prepared Ag using NaCl, KBr, KI as halogen sources₂WO₄the/AgX (X ═ Cl, Br, I) photocatalyst is used for methyl orange degradation and shows a better than pure Ag₂WO₄high photocatalytic performance [ Jingjing Li, et al. (2015) ]simple formation of Ag₂WO₄/AgX(X＝Cl,Br,I)hybrid nanorods with enhanced visible-light-driven photoelectrochemicalproperties”Materials Research Bulletin 61:315-320]. As described above for Ag₂WO₄The photocatalytic performance is modified by a two-step ion exchange method, and the prepared Ag₂WO₄Are all alpha-Ag₂WO₄。

disclosure of Invention

The invention aims to provide a method for synthesizing Z-Scheme AgBr/beta-Ag in one step₂WO₄a method of photocatalyst.

The technical solution for realizing the purpose of the invention is as follows: construction of direct Z-Scheme AgBr/beta-Ag₂WO₄Systematic photocatalyst, AgBr/beta-Ag₂WO₄The space separation of the photoproduction electrons and the holes is realized by the mass ratio of 5 to 30 percent, thereby improving the photocatalysis performance.

The Z-Scheme AgBr/beta-Ag is synthesized in one step₂WO₄The preparation method of the photocatalyst comprises the following steps:

firstly, adding cetyl trimethyl ammonium bromide into a silver nitrate solution, and magnetically stirring for 2 hours to form a mixed solution in which AgBr sol and silver ions coexist;

Secondly, dissolving sodium tungstate in water with the same volume as the silver nitrate solution in the first step;

Step three, dropwise adding the solution obtained in the step one into the solution obtained in the step two, and magnetically stirring for 6 hours at room temperature in a dark condition;

Fourthly, centrifugally washing and drying the sample obtained in the third step to prepare AgBr/beta-Ag₂WO₄A composite material.

further, in the first step, the concentration of silver nitrate is 20mM, and the concentration of cetyl trimethyl ammonium bromide is 7.5% -27% of the concentration of silver nitrate.

Further, in the second step, the concentration of the sodium tungstate solution is 0.5 times of that of the silver nitrate solution in the first step.

Furthermore, in the fourth step, the rotating speed of the centrifuge is 9000r/min, the centrifugation time is 3min, and the temperature of the oven is 60 ℃.

Compared with the prior art, the invention has the advantages that: (1) adopting one-step method to prepare AgBr/beta-Ag₂WO₄The composite material has mild reaction conditions and simple operation; (2) the material is used for photocatalytic degradation of rhodamine B, and shows excellent catalytic performance.

drawings

FIG. 1 is a synthetic scheme of the present invention.

FIG. 2(a) is an XRD diffraction pattern of comparative examples 1 and 2 of the present invention and (b) is an XRD diffraction pattern of materials prepared according to examples 1 to 4.

FIG. 3(a) is a scanning electron micrograph of a comparative example 1, (b) is a comparative example 2, (c) is a scanning electron micrograph of a material prepared in example 4, (d) is a comparative example 1, (e) is a comparative example 2, and (f) and (g) are transmission electron micrographs of a material prepared in example 4.

FIG. 4 is (a) a graph showing the variation of RhB concentration with time and (b) a graph showing the photocatalytic rate of the material prepared in examples 1 to 4 of the present invention and comparative examples 1 and 2 for photocatalytic degradation of RhB.

FIG. 5(a) is a photocurrent spectrum and (b) is an electrochemical impedance spectrum of materials prepared in example 4(I) of the present invention and comparative examples 1(III), 2 (II).

FIG. 6 is a diagram showing the photocatalytic mechanism of the material prepared in the example of the present invention.

Detailed Description

FIG. 1 is a synthetic flow chart of the present invention, cetyl trimethyl ammonium bromide is added into silver nitrate solution, and magnetic stirring is performed for 2 hours to form a mixed solution in which AgBr sol and silver ions coexist; sodium tungstate was dissolved in an equal volume of water as the silver nitrate solution. Dropwise adding silver nitrate solution containing hexadecyl trimethyl ammonium bromide into sodium tungstate solution, stirring at room temperature in a dark place for 6 hours, centrifuging, washing and drying to obtain AgBr/beta-Ag₂WO₄A composite material.

AgBr/beta-Ag prepared by the invention₂WO₄The composite material has excellent photocatalytic performance as a photocatalyst, which is mainly attributed to AgBr and beta-Ag₂WO₄The Z-scheme heterojunction is formed between the two layers, so that space separation of photon-generated electrons and holes is realized, and the carrier recombination efficiency is reduced, thereby greatly improving the photocatalytic performance.

AgBr/beta-Ag of the invention₂WO₄the composite photocatalyst is prepared by the following steps:

Firstly, adding cetyl trimethyl ammonium bromide into a silver nitrate solution, and magnetically stirring for 2 hours to form a mixed solution in which AgBr sol and silver ions coexist;

secondly, dissolving sodium tungstate in water with the same volume as the silver nitrate solution in the first step;

Step three, dropwise adding the solution obtained in the step one into the solution obtained in the step two, and stirring at room temperature in a dark place for 6 hours;

step four, the sample obtained in the step three is centrifugally washed and dried in a drying oven to prepare AgBr/beta-Ag₂WO₄a composite material.