阅读说明：本技术 高可见光催化活性的BiOCl纳米光催化剂的制备方法和应用 (Preparation method and application of BiOCl nano photocatalyst with high visible light catalytic activity ) 是由 王立艳 盖广清 于 2021-08-18 设计创作，主要内容包括：本发明涉及光催化剂技术领域,具体是提供了一种简单、易于操作、不使用任何有机溶剂和特殊设备,在室温下即可快速合成高可见光催化活性的BiOCl光催化剂的方法。所述方法包括：S1、将一定量的聚乙二醇溶于去离子水中,再加入水溶性铋盐或其水合物,充分搅拌；S2、将一定量的水溶性氯盐加入上述溶液中,室温下充分搅拌；S3、分离产生的沉淀物、洗涤、干燥、得到BiOCl纳米光催化剂粉末。本发明方法合成的BiOCl纳米光催化剂的微观形貌为高分散性的纳米片或由纳米片组装而成的纳米花,在LED灯带下,催化剂表现出突出的可见光催化活性,解决现有技术存在的产物可见光催化活性低、制备过程复杂、安全隐患大、不环保、能耗高等问题。(The invention relates to the technical field of photocatalysts, and particularly provides a method for quickly synthesizing a BiOCl photocatalyst with high visible-light catalytic activity at room temperature, which is simple and easy to operate, and does not use any organic solvent or special equipment. The method comprises the following steps: s1, dissolving a certain amount of polyethylene glycol in deionized water, adding water-soluble bismuth salt or hydrate thereof, and fully stirring; s2, adding a certain amount of water-soluble chloride salt into the solution, and fully stirring at room temperature; and S3, separating the generated precipitate, washing and drying to obtain BiOCl nano photocatalyst powder. The microscopic morphology of the BiOCl nano photocatalyst synthesized by the method is a nano sheet with high dispersibility or a nano flower assembled by the nano sheet, and the catalyst shows outstanding visible light catalytic activity under an LED lamp belt, so that the problems of low visible light catalytic activity of a product, complex preparation process, large potential safety hazard, environmental pollution, high energy consumption and the like in the prior art are solved.)

1. A preparation method of a BiOCl photocatalyst with high visible light catalytic activity is characterized by comprising the following steps:

s1, dissolving a certain amount of polyethylene glycol in deionized water, adding water-soluble bismuth salt or hydrate thereof, and fully stirring;

s2, adding a certain amount of water-soluble chloride salt into the solution, and fully stirring at room temperature;

and S3, separating the generated precipitate, washing and drying to obtain BiOCl nano photocatalyst powder.

2. The method according to claim 1, wherein the molecular weight of the polyethylene glycol in S1 is 200-10000.

3. The method according to claim 1, wherein the water-soluble bismuth salt in S1 is bismuth nitrate (Bi (NO) pentahydrate₃)₃〃5H₂O or bismuth chloride.

4. The production method according to claim 1, wherein the stirring in S1 is stirring at room temperature for 30 to 60 min.

5. The method according to claim 1, wherein the molar ratio of polyethylene glycol to bismuth salt in S1 is 0.01-4: 1.

6. The method according to claim 1, wherein in S2, the water-soluble chlorine salt is potassium chloride or sodium chloride; the molar ratio of the dosage of the bismuth nitrate pentahydrate to the bismuth nitrate pentahydrate is 1: 1.

7. The production method according to claim 1, wherein the stirring in S2 is stirring at room temperature for 30 to 60 min.

8. The method according to claim 1, wherein the drying condition in S3 is vacuum drying, the drying temperature is 40-60 ℃, and the drying time is 12-24 h.

9. A method for photocatalytic degradation of organic pollutants, comprising: firstly, the BiOCl nano photocatalyst prepared by the preparation method of any one of claims 1 to 8 is added into a solution containing organic pollutants for dark adsorption, and then an LED lamp is used for irradiating the BiOCl photocatalyst material; or directly irradiating the solution containing the organic pollutants by using an LED lamp without dark adsorption.

10. The method of claim 9, wherein the organic contaminant is rhodamine B; when the LED lamp is irradiated, the LED lamp strip is white light, 32W.

Technical Field

The invention relates to the technical field of photocatalysts, in particular to a preparation method of a BiOCl nano photocatalyst with high visible light catalytic activity.

Background

Bismuth oxychloride (BiOCl) has been reported in the prior art as a photocatalyst or electrode material. As an inorganic material photocatalyst, the inorganic material is prepared by different preparation methods, and different micro-morphologies can be obtained, and the different micro-morphologies determine the strength of the inorganic material with different catalytic properties and catalytic abilities.

For example, the invention patent CN 110240197 a discloses an ultrathin nanosheet self-assembled multilayer BiOCl microsphere and its application in photocatalytic coupling of benzylamine to imine. The scheme takes pentahydrate bismuth nitrate and potassium chloride as raw materials, takes ethylene glycol as a solvent, adds a surfactant PVPK30, and prepares the nano-sheet self-assembled multi-layer BiOCl microsphere by a solvothermal method reaction for 14h at 160 ℃ in a high-pressure reaction kettle, and the nano-sheet self-assembled multi-layer BiOCl microsphere is applied to the oxidative coupling of benzylamine to convert the benzylamine into imine, and experiments prove that the conversion rate of the benzylamine reaches 61% after 6h of illumination. The method has the problems of long reaction time, high reaction pressure, potential explosion hazard, high energy consumption, large amount of glycol with certain toxicity and the like. The prepared BiOCl microsphere is used for converting benzylamine into imine through oxidative coupling, and the degradation catalysis of other organic pollutants is not studied. The invention patent CN 108467062A discloses a rosette BiOCl and application thereof as an electrode material, the preparation process is similar to CN 110240197A, bismuth nitrate pentahydrate and sodium chloride are added into an ethylene glycol solvent and stirred for 2h, then the mixture is transferred into a high-pressure reaction kettle, the solvothermal reaction is carried out for 6h at 170 ℃, the rosette BiOCl is obtained, and the BiOCl is used as the electrode material. The scheme also has the problems of high reaction pressure, explosion hidden danger, high energy consumption, large amount of glycol with certain toxicity and the like, and the scheme also does not research the degradation catalytic performance of BiOCl on other organic pollutants. Patent CN 104475131B discloses a visible light response type nano-flake bismuth oxychloride catalyst and a preparation method thereof, wherein bismuth nitrate pentahydrate is added into a mixed solution of concentrated hydrochloric acid and isopropanolamine, stirred and dissolved at room temperature, and the pH value is adjusted to 4-7 by ammonia water to prepare nano-flake bismuth oxychloride. The reaction is carried out at normal temperature, although an autoclave is not used, isopropanolamine and 37.5 percent concentrated hydrochloric acid are mixed as a solvent in the reaction, and ammonia water is used for adjusting the pH value, so that the isopropanolamine and the ammonia water have certain-range DEG C damage to eyes, skin, oral cavity, nasal cavity mucosa and respiratory system, and the production environment safety and the environmental protection are poor. The invention patent CN 108855011A discloses a composite material with synergistic effects of adsorption and visible light catalytic degradation. The preparation method comprises the steps of mixing bismuth nitrate pentahydrate, activated carbon fiber, potassium chloride and potassium iodide in solvents such as ethylene glycol and glycerol, transferring the mixture into a high-pressure hydrothermal kettle, and reacting for 10-16h at the temperature of 180 ℃ with 120-. Dispersing the obtained composite material in acetonitrile, N-dimethylformamide and N, N-dimethylacetamide solvents, adding a silane coupling agent, stirring for 4-8h at the temperature of 60-80 ℃, adding a polyethyleneimine aqueous solution, and stirring for 4-6h to obtain the polyethyleneimine grafted carbon fiber loaded bismuth oxyiodide/bismuth oxychloride. The scheme needs high-pressure hydrothermal reaction and has high energy consumption. The complex solvent of acetonitrile, N-dimethylformamide and N, N-dimethylacetamide is irritant, highly toxic, inflammable and volatile. The composite material takes the activated carbon fiber as a carrier, and the polyethyleneimine with positive charge is grafted to ensure that the material has adsorbability and can adsorb molecules with negative charge, and the bismuth oxyiodide or bismuth oxychloride loaded on the carrier has no adsorbability.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method capable of quickly synthesizing BiOCl photocatalyst at room temperature, which has the advantages of simple synthesis process, easy operation, no use of any organic solvent and special equipment (such as an autoclave), environmental protection and high safety, and the synthesized BiOCl nano photocatalyst is a nano sheet with high dispersibility or a nano flower micro-morphology assembled by the nano sheet, and the catalyst shows outstanding visible light catalytic activity even under the action of an LED lamp strip (32W), has high adsorbability, and solves the problems of low visible light catalytic activity, complex preparation process, large potential safety hazard, environmental protection, high energy consumption and the like of a BiOCl product in the prior art.

The technical scheme of the invention is as follows:

a preparation method of a BiOCl nano photocatalyst with high visible light catalytic activity comprises the following steps:

s1, dissolving a certain amount of polyethylene glycol in deionized water, adding water-soluble bismuth salt or hydrate thereof, and fully stirring;

s2, adding a certain amount of water-soluble chloride salt into the solution, and fully stirring at room temperature;

s3, separating the generated precipitate, washing and drying to obtain BiOCl powder.

Preferably, in S1, the molecular weight of polyethylene glycol is 200-10000.

Wherein, polyethylene glycol with various molecular weights can be mixed for use.

Preferably, in S1, the water-soluble bismuth salt is bismuth nitrate pentahydrate Bi (NO)₃)₃〃5H₂O or bismuth chloride.

Preferably, the stirring in S1 is stirring at normal temperature for 30-60 min.

Preferably, in S1, the molar ratio of the polyethylene glycol to the bismuth nitrate pentahydrate is 0.01-4: 1; the specific dosage ratio is related to the polyethylene glycol molecule.

Preferably, in S2, the water-soluble chloride salt is potassium chloride or sodium chloride; the molar ratio of the dosage of the bismuth nitrate pentahydrate to the bismuth nitrate pentahydrate is 1: 1.

Preferably, the stirring in S2 is stirring at normal temperature for 30-60 min.

Preferably, in S3, the drying condition is vacuum drying below 60 ℃, and the drying time is 12-24 h; preferably 40 ℃ and dried for 20 h. The drying can be drying by an air drying oven, or vacuum drying, or air drying at room temperature, wherein the vacuum drying can be carried out at a lower temperature to prevent the product from oxidative deterioration due to overhigh temperature, and the drying speed at room temperature is too slow, and the specific drying time is determined according to the water content of the product.

A method for carrying out photocatalytic degradation on organic pollutants by using the BiOCl nano photocatalyst comprises the following steps: firstly, the BiOCl photocatalyst prepared in any embodiment is added into an organic pollutant aqueous solution for dark adsorption, and then an LED lamp strip is used for irradiating the BiOCl photocatalyst material; or the solution is directly irradiated by using the LED lamp strip without dark adsorption, and the organic pollutants are degraded through photocatalytic reaction. Preferably, the organic contaminant is rhodamine B.

In this application, room temperature and room temperature are used in the same sense, and the natural temperature in a laboratory can be generally interpreted to be 20 to 35 ℃.

Compared with the prior art, the invention has the technical effects that:

(1) the preparation method provided by the invention has the advantages that the preparation method is operated at normal temperature and normal pressure except for drying, the synthesis route is simple, the synthesis reaction can be carried out at normal temperature, special equipment such as an autoclave is not needed, heating is not needed, the preparation process is simple, the operation is easy, the safety is high, the equipment cost and the energy consumption cost are low.

(2) The preparation method only uses deionized water and polyethylene glycol except for basic raw materials, does not introduce an organic solvent in the whole reaction, is safe and environment-friendly, avoids the trouble of recovery and post-treatment of the organic solvent, is non-toxic and harmless, does not generate the hidden danger of flammability and poisoning, is environment-friendly, has high production safety, is easy to recover the polyethylene glycol (particularly, the polyethylene glycol is solid when more than 800 times of the volume of the polyethylene glycol and can be added into 10 times of the volume of the glacial ethyl ether for precipitation by concentrating the polyethylene glycol solution so as to conveniently recover the polyethylene glycol, and the polyethylene glycol is difficult to recover when the volume of the polyethylene glycol is less than 600, has the yield close to 100 percent, has high catalyst efficiency, can be repeatedly utilized, and is suitable for large-scale industrial production.

(3) The sample obtained by the method is a high-dispersity nanosheet or BiOCl nanoflower assembled by nanosheets, the diameter of the nanoflower is about 1-3 mu m, and the thickness of the nanosheet is about 10 nanometers.

(4) The BiOCl nano photocatalyst prepared by the invention has excellent photocatalytic degradation efficiency. Tests show that after dark adsorption for 60min, the adsorption rate of BiOCl nanoflower on RhB solution (Rodamia Rohdea B) reaches 54%, the RhB adsorbed by the catalyst is changed into red, and then the RhB solution is degraded into colorless within 15min through irradiation of an LED lamp strip (32W, white light), the degradation rate reaches 100%, and the catalyst is changed into colorless within 70 min. If the BiOCl powder is directly put into the RhB solution, the RhB solution is directly irradiated by an LED lamp strip (white light, 32W) without dark adsorption, the RhB solution is degraded to be nearly colorless within 15min, and the catalyst is completely colorless within 70 min. Directly irradiating with xenon lamp (wavelength λ > 390nm, 300W) to completely degrade RhB solution and catalyst into colorless within 6min, with degradation rate of 100%.

The BiOCl nano photocatalyst prepared by the invention has outstanding visible light catalytic activity under the irradiation of an LED lamp strip (32W, white light), so that the BiOCl nano photocatalyst can be applied to the degradation of indoor organic pollutants. The invention solves the problems of complex preparation, multiple types of used reagents, high consumption of organic solvents, toxic pollution to production environment, high potential safety hazard, high energy consumption, high cost and the like in the prior art.

Drawings

Fig. 1 is an XRD pattern of the bismuth oxychloride samples prepared in example 1 and comparative example 1.

FIG. 2 is SEM photographs at different magnifications of bismuth oxychloride samples prepared in example 1 of the invention and comparative example 1; (a, b) SEM photograph of bismuth oxychloride of example 1; and (c, d) are SEM photographs of the bismuth oxychloride of comparative example 1.

FIG. 3 is a TEM photograph of a sample of bismuth oxychloride prepared in example 1 of the present invention.

FIG. 4 is an SEM photograph of samples of bismuth oxychloride prepared in examples 2(a) and 12(b) of the present invention.

FIG. 5 is a graph showing the photocatalytic degradation effect of bismuth oxychloride on rhodamine B, which is prepared in example 1 and comparative example 1 of the present invention; wherein (a) is a change curve of the absorbance of the rhodamine B solution along with time under the action of the catalyst in the embodiment 1, wherein the dark adsorption is carried out firstly, and then the LED lamp irradiates; in the figure, the curves correspond to no photocatalyst, dark adsorption for 60min, LED illumination for 5min, LED illumination for 10min and LED illumination for 15min from top to bottom in sequence; (b) under the action of the catalyst in the comparative example 1, dark adsorption is carried out firstly, then LED lamp irradiation is carried out, and the change curve of the absorbance of the rhodamine B solution along with time is obtained; in the figure, the curve corresponds to no photocatalyst, dark adsorption for 60min, LED illumination for 5min, LED illumination for 10min, LED illumination for 15min, LED illumination for 20min, LED illumination for 30min and LED illumination for 40min from top to bottom in sequence; (c) under the action of the catalysts in the embodiment 1 and the comparative example 1, when dark adsorption is carried out and then the LED lamp is irradiated, a degradation rate curve of a rhodamine B solution is obtained; (d) under the action of the catalysts in the embodiment 1 and the comparative example 1, the degradation rate curve of the rhodamine B solution is directly irradiated by an LED lamp; (e) the degradation rate curve of the rhodamine B solution is directly irradiated by a xenon lamp under the action of the catalysts in the embodiment 1 and the comparative example 1.

Detailed Description

The technical scheme of the invention comprises the following steps:

a preparation method of a BiOCl nano photocatalyst with high visible light catalytic activity comprises the following steps:

s1, dissolving a certain amount of polyethylene glycol in deionized water, adding water-soluble bismuth salt or hydrate thereof, and fully stirring;

s2, adding a certain amount of water-soluble chloride salt into the solution, and fully stirring at room temperature;

and S3, separating the generated precipitate, washing and drying to obtain BiOCl nano photocatalyst powder.

Preferably, in S1, the molecular weight of polyethylene glycol is 200-10000.

Preferably, in S1, the water-soluble bismuth salt is bismuth nitrate pentahydrate Bi (NO)₃)₃〃5H₂O or bismuth chloride.

Preferably, the stirring in S1 is stirring at normal temperature for 30-60 min.

Preferably, in S1, the molar ratio of polyethylene glycol to bismuth nitrate pentahydrate is 0.01-4:1, and specifically, when the molecular weight of polyethylene glycol is 10000, the molar ratio of polyethylene glycol to bismuth nitrate is 0.01-0.5: 1;

when the molecular weight of the polyethylene glycol is 8000, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.02-0.5: 1;

when the molecular weight of the polyethylene glycol is 6000, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.04-0.5: 1;

when the molecular weight of the polyethylene glycol is 4000, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.06-0.6: 1;

when the molecular weight of the polyethylene glycol is 2000, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.1-1.5: 1;

when the molecular weight of the polyethylene glycol is 1000, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.2-2: 1;

when the molecular weight of the polyethylene glycol is 600, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.3-3: 1;

when the molecular weight of the polyethylene glycol is 400, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.35-3.5: 1;

when the molecular weight of the polyethylene glycol is 200, the molar ratio of the polyethylene glycol to the bismuth nitrate is 0.5-4: 1.

polyethylene glycol is a morphology control agent and a dispersing agent when bismuth oxychloride is formed, and when the using amount is lower than the range, the generated bismuth oxychloride sheet layer is thicker and has poor dispersibility; when the amount of the polyethylene glycol exceeds the above range, a large amount of polyethylene glycol is wasted or covers the surface of bismuth oxychloride, and the photocatalytic performance of the bismuth oxychloride is affected.

The water is a solvent for hydrolysis precipitation reaction, the use amount is small, the hydrolysis precipitation reaction of bismuth nitrate and potassium chloride can be influenced, the dispersity is poor, the production capacity of equipment is reduced if the use amount is large, and the influence of changing the water use amount in a certain range on the performance of a product is small.

Preferably, in S2, the water-soluble chloride salt is potassium chloride or sodium chloride, and the molar ratio of the water-soluble chloride salt to the bismuth nitrate pentahydrate is 1: 1.

Preferably, the stirring in S2 is stirring at normal temperature for 30-60 min.

Preferably, in S3, vacuum drying is carried out, the drying temperature is 40-60 ℃, and the drying time is 12-24 h; preferably 50 ℃ and dried for 20 h. The low-temperature vacuum drying is mainly used for preventing the oxidation reaction of the bismuth oxychloride at high temperature, generally, the time is long when the temperature is low, the time is short when the temperature is high, and the vacuum drying at 60 ℃ can also be adopted.

The reaction principle for preparing the BiOCl photocatalyst comprises the following steps: raw material bismuth nitrate pentahydrate with the molecular formula of Bi (NO)₃)₃〃5H₂O, hydrolyzed to bismuth subnitrate BiO (NO) when meeting water₃) After addition of KCl, Cl^-Then substituted for NO₃ ^-And BiOCl is generated. Polyethylene glycol is a nonionic surfactant, and can be regarded as consisting of several CH₂CH₂The structural unit of O is repeatedly linked, the molecular chain contains many oxygen atoms, Bi³⁺Can generate coordination with polyethylene glycol and water to generate bismuth-containing poly complexThe reaction process with the chloride ion can be orderly carried out. Therefore, the polyethylene glycol plays a role in controlling the appearance in the BiOCl generation process. In addition, the polyethylene glycol is also a nonionic surfactant and has stronger dispersion effect and morphology control effect.

In order to explain the technical solution and effects of the present invention, the following is further described with reference to specific examples and comparative examples.

Example 1

Dissolving 1mmol of polyethylene glycol 2000 in 40mL of deionized water, adding 2mmol of bismuth nitrate pentahydrate, stirring at room temperature for 30min, adding 2mmol of potassium chloride, and stirring for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 40 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 1 shows that after dark adsorption for 60min, the adsorption degradation rate is 54%, and then irradiation is carried out by using a Led lamp (32W), so that the 10min degradation rate is 98% and the 15min degradation rate is 100%.

Comparative example 1

Firstly, 1mmol of bismuth nitrate pentahydrate is dissolved in 40mL of deionized water, stirred for 40min at room temperature, then 1mmol of potassium chloride is added, and stirred for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at 40 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance research on the comparative preparation sample shows that after dark adsorption for 60min, the adsorption degradation rate is 26%, and then irradiation is carried out by using an Led lamp (32W), the degradation rate is 48% in 15min, 57% in 20min and 77% in 30 min.

The crystalline structures and the micro-morphologies of the two BiOCl powder products prepared in example 1 and comparative example 1 were characterized by means of testing such as an X-ray diffractometer, a scanning electron microscope, and a transmission electron microscope.

As shown in fig. 1, the XRD patterns of the BiOCl powders prepared in example 1 and comparative example 1 are shown. Comparing standard card PDF06-0249, it can be seen that the method of the present invention indeed produced BiOCl; the XRD pattern of comparative example 1 shows higher peak intensity of crystallization, indicating that the BiOCl product modified without polyethylene glycol is pure and has better crystallinity; the XRD chart of example 1 shows that the intensity of the crystalline peak of the prepared BiOCl product is reduced, and particularly, the characteristic peaks corresponding to the crystal faces of (001), (002), (101) and (102) are obviously reduced, which is mainly influenced by the amorphous polyethylene glycol.

As shown in fig. 2, are SEM photographs of the BiOCl powder prepared in example 1 and comparative example 1 at different magnifications. As can be seen from fig. 2a and b, the BiOCl powder sample prepared in example 1 is a spherical nanoflower assembled from nanosheets, the nanoflower diameter is about 1-2 μm, and the nanosheet thickness is about 10 nm. The nano sheets forming the nanoflower are orderly arranged, the stacking phenomenon does not exist, the thickness is thin, and mainly polyethylene glycol plays a role in dispersing and controlling the morphology. The micro-porous structure on the surface of the microsphere is beneficial to the adsorption and mass transfer of the microsphere to dye, thereby showing better dye-sensitized visible light photocatalytic activity.

As can be seen from fig. 2c and d, the BiOCl powder sample prepared in comparative example 1 mainly consists of nanosheets, the thickness of the nanosheets is about 40nm, the nanosheets are partially dispersed, and the nanosheets are partially stacked together. Compared with the nanoflower morphology of fig. 2a and b, the nanosheets are thicker, partially stacked and have poor dispersibility, which is the reason for poor photocatalytic performance.

As shown in fig. 3, is a TEM photograph of the BiOCl powder prepared in example 1. The TEM picture further verifies that the microscopic morphology of the BiOCl powder sample is spherical nanoflower formed by assembling nanosheets.

Example 2

0.1mmol of polyethylene glycol 2000 is dissolved in 40mL of deionized water, 1mmol of bismuth nitrate pentahydrate is added, the mixture is stirred at room temperature for 30min, 1mmol of potassium chloride is added, and the mixture is stirred for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 40 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the sample prepared in example 2 shows that after dark adsorption for 60min, the adsorption degradation rate is 40%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 74%, the 15min degradation rate is 81%, and the 20min degradation rate is 92%.

The sample of example 2 was characterized for its microtopography using a scanning electron microscope, as shown in FIG. 4 a. It can be seen that the BiOCl sample prepared in example 2 mainly has a nanosheet shape, the nanosheet has good dispersibility, and a small amount of nanoflower shapes are available, and the nanoflower diameter is about 2-3 μm. The BiOCl sample with the nanosheets and the nanoflowers with good dispersibility can also have excellent photocatalytic performance.

Example 3

Dissolving 1.5mmol of polyethylene glycol 2000 in 40mL of deionized water, adding 1mmol of bismuth nitrate pentahydrate, stirring at room temperature for 30min, adding 1mmol of potassium chloride, and stirring for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate for 14 hours in a vacuum drying oven at the temperature of 45 ℃ to obtain BiOCl powder.

The photocatalysis performance research of the sample prepared in the example 3 shows that after dark adsorption is carried out for 60min, the adsorption degradation rate of the rhodamine B solution is 45%, then the rhodamine B solution is irradiated by an LED lamp (32W), the degradation rate of the rhodamine B solution is 80% after illumination for 10min, the degradation rate of the rhodamine B solution is 88% after illumination for 15min, and the degradation rate of the rhodamine B solution is 95% after illumination for 20 min.

Example 4

0.4mmol of polyethylene glycol 1000 is dissolved in 30mL of deionized water, 1mmol of bismuth nitrate pentahydrate is added, the mixture is stirred at room temperature for 30min, 1mmol of potassium chloride is added, and the mixture is stirred for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 40 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the sample prepared in example 4 shows that after dark adsorption for 60min, the adsorption degradation rate of the rhodamine B solution is 43%, and then the rhodamine B solution is irradiated by an LED lamp (32W), wherein the degradation rate of the rhodamine B solution is 75% after illumination for 10min, the degradation rate of the rhodamine B solution is 84% after illumination for 15min, and the degradation rate of the rhodamine B solution is 95% after illumination for 20 min.

Example 5

0.4mmol of polyethylene glycol 4000 is firstly dissolved in 40mL of deionized water, 1mmol of bismuth nitrate pentahydrate is then added, the mixture is stirred for 30min at room temperature, 1mmol of potassium chloride is added, and the mixture is stirred for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 55 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 5 shows that after dark adsorption for 60min, the adsorption degradation rate is 52%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 70%, the 15min degradation rate is 88%, and the 20min degradation rate is 98%.

Example 6

0.2mmol of polyethylene glycol 6000 is dissolved in 40mL of deionized water, 1mmol of bismuth nitrate pentahydrate is added, the mixture is stirred for 40min at room temperature, 1mmol of potassium chloride is added, and the mixture is stirred for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 50 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 6 shows that after dark adsorption for 60min, the adsorption degradation rate is 57%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 79%, the 15min degradation rate is 97%, and the 20min degradation rate is 99%.

Example 7

Dissolving 0.2mmol of polyethylene glycol 8000 into 40mL of deionized water, adding 1mmol of bismuth nitrate pentahydrate, stirring at room temperature for 30min, adding 1mmol of potassium chloride, and stirring for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 60 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 7 shows that after dark adsorption for 60min, the adsorption degradation rate is 55%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 90%, the 15min degradation rate is 97%, and the 20min degradation rate is 99%.

Example 8

0.2mmol of polyethylene glycol 10000 is dissolved in 40mL of deionized water, 1mmol of bismuth nitrate pentahydrate is added, the mixture is stirred for 60min at room temperature, 1mmol of potassium chloride is added, and the mixture is stirred for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 60 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the sample prepared in example 8 shows that after dark adsorption for 60min, the adsorption degradation rate is 55%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 88%, the 15min degradation rate is 97%, and the 20min degradation rate is 98%.

Example 9

Dissolving 1.7mmol of polyethylene glycol 600 in 40mL of deionized water, adding 1mmol of bismuth nitrate pentahydrate, stirring at room temperature for 30min, adding 1mmol of potassium chloride, and stirring for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 40 ℃ for 12 hours to obtain BiOCl powder. Polyethylene glycol 600 is in a liquid state, and the reaction waste liquid cannot be recovered.

The photocatalytic performance study of the samples prepared in example 9 shows that after dark adsorption for 60min, the adsorption degradation rate is 40%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 72%, the 15min degradation rate is 85%, and the 20min degradation rate is 92%.

Example 10

0.1mmol of polyethylene glycol 20000 is firstly dissolved in 40mL of deionized water, then 1mmol of bismuth nitrate pentahydrate is added, after stirring for 30min at room temperature, 1mmol of potassium chloride is added, and stirring is carried out for 60 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 60 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the sample prepared in example 10 shows that after dark adsorption for 60min, the adsorption degradation rate is 60%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 80%, the 15min degradation rate is 87%, and the 20min degradation rate is 92%.

Compared with the example 8, the photocatalytic activity is reduced, and although the degradation rate of rhodamine B is more than 90% after 20min illumination, the monovalent cost of the polyethylene glycol 20000 is far higher than that of polyethylene glycol with other molecular weights.

Example 11

Dissolving 2mmol of polyethylene glycol 2000 in 40mL of deionized water, adding 1mmol of bismuth nitrate pentahydrate, stirring at room temperature for 30min, adding 1mmol of potassium chloride, and stirring for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate in a vacuum drying oven at the temperature of 50 ℃ for 12 hours to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 11 showed that after dark adsorption for 60min, the adsorption degradation rate was 48%, and then irradiation with Led lamp (32W) resulted in a 10min degradation rate of 80%, a 15min degradation rate of 91%, and a 20min degradation rate of 95%.

The data of the photocatalytic tests of the comparative examples 1, 3 and 11 show that when the molar ratio of the polyethylene glycol 2000 to the bismuth nitrate is increased from 0.5 to 1.5, the degradation rate of the rhodamine B is reduced, and when the molar ratio of the polyethylene glycol 2000 to the bismuth nitrate is 2, the degradation rate of the rhodamine B is obviously reduced. When the dosage of the polyethylene glycol is too much, the excessive polyethylene glycol covers the surface of the bismuth oxychloride, so that the photocatalytic performance of the bismuth oxychloride is affected, and a large amount of raw materials are wasted.

The photocatalytic performance research of the BiOCl powder prepared in the examples 2-11 shows that after dark adsorption is carried out for 60min, the degradation rate of the rhodamine B solution reaches more than 90% after the LED lamp is used for irradiating for 20 min.

Example 12

0.02mmol of polyethylene glycol 2000 is dissolved in 40mL of deionized water, 1mmol of bismuth nitrate pentahydrate is added, stirring is carried out at room temperature for 30min, 1mmol of potassium chloride is added, and stirring is carried out for 40 min. And (4) carrying out centrifugal separation on the precipitate, washing the precipitate to be neutral by deionized water, and drying the precipitate for 15 hours in a vacuum drying oven at the temperature of 40 ℃ to obtain BiOCl powder.

The photocatalytic performance study of the samples prepared in example 12 shows that after dark adsorption for 60min, the adsorption degradation rate is 30%, and then irradiation is performed by using a Led lamp (32W), the 10min degradation rate is 60%, the 15min degradation rate is 68%, and the 20min degradation rate is 72%.

The sample of example 12 was characterized for its microtopography using a scanning electron microscope, as shown in FIG. 4 b. It can be seen that the prepared BiOCl sample presents the shape of the nanosheet, nanoflowers are not observed, the nanosheet has partial stacking phenomenon, and the dispersibility is poor, so that the BiOCl sample is the main reason for low photocatalytic efficiency.

The BiOCl photocatalyst powder prepared by the invention has the microscopic morphology of nano-sheets or nano-flowers, the better the dispersibility is, the better the photocatalytic performance of the thin nano-sheets is, otherwise, the nano-sheets are thicker, and the nano-flowers are mostly spherical with high adsorbability.

The BiOCl powders prepared in examples 1-12 and comparative example 1 were subjected to adsorption and photocatalytic degradation experiments to prepare RhB solutions (concentration 10mg/L), and the concentrations of the RhB solutions in the experiments were equal.

The BiOCl powder catalyst samples prepared in examples 1-12 and comparative example 1 were subjected to dark adsorption and then to illumination mode test, and the dark adsorption rate for 60min and the degradation rate of RhB solution after Led (32W) illumination were as follows:

the adsorption rate and the degradation rate of RhB in the RhB solution are obtained by measuring and calculating the absorbance through an ultraviolet-visible spectrophotometer.

The ability of the BiOCl powder catalyst prepared in example 1 and the BiOCl powder prepared in comparative example 1 to degrade RhB with light was further compared under different light conditions.

(1) First dark adsorption and then LED lamp strip (white light, 32W) irradiation (as shown in figures 5a-c)

The BiOCl powder catalyst prepared in example 1 was put into the RhB solution, dark-absorbed for 60min, and then irradiated by an LED lamp strip (white light, 32W), the degradation rate of the RhB solution reached 100% within 15min, the solution became colorless, and the catalyst powder became colorless completely within 70 min.

The comparative sample prepared in comparative example 1 was put into RhB solution, dark-absorbed for 60min, and then irradiated by an LED strip (white light, 32W), after LED illumination for 30min, the degradation rate of RhB solution was only 77%, and the catalyst powder still had a deep pink color.

(2) No dark absorption was directly illuminated with a LED strip (white light, 32W) (as shown in fig. 5 d).

The BiOCl powder prepared in example 1 was added into the RhB solution, and directly irradiated with an LED lamp strip (white light, 32W) without dark adsorption, the RhB solution was degraded to nearly colorless within 15min, and the catalyst was completely colorless within 70 min.

The comparative sample prepared in comparative example 1 was added to the RhB solution, and directly irradiated with an LED strip (white light, 32W) without dark adsorption, and the degradation rate of the RhB solution was only 72% after 30 min.

(3) Direct irradiation with xenon lamp (λ > Tg 390nm, 300W) without dark adsorption (as shown in FIG. 5 e).

The BiOCl powder prepared in example 1 was put into RhB solution and directly irradiated with xenon lamp (λ > 390nm, 300W) without dark adsorption, and the RhB solution and the catalyst were completely degraded to colorless within 6 min.

The comparative sample prepared in comparative example 1 was placed in RhB solution and directly irradiated with xenon lamp (λ > 390nm, 300W) without dark adsorption, after 20min the RhB solution and the catalyst were reduced to colorless.

From the comparison of the dark adsorption rates, the adsorption rate of the BiOCl powder catalyst sample prepared in the example 1 of the invention to the RhB solution is far better than that of the sample prepared in the comparative example 1.

In terms of adsorption performance, for examples 1-11, after dark adsorption for 60min, the adsorption degradation rate of the catalyst to rhodamine B is higher than 40%, the catalyst has better adsorption performance, more rhodamine B molecules are adsorbed on the surface of the catalyst, the photosensitization effect of the organic dye is enhanced, and the photocatalytic efficiency is improved. However, example 12 and comparative example 1 had lower adsorption performance. The method shows that in the process of preparing the BiOCl powder, the dosage of the polyethylene glycol has an influence on the adsorption performance of the BiOCl powder product, the molecular weight and dosage of the polyethylene glycol are key factors influencing the adsorption performance of the BiOCl powder, the dosage of the polyethylene glycol with low molecular weight needs to be more, and the dosage of the polyethylene glycol with high molecular weight needs to be less, so that better adsorption performance can be achieved.

As can be seen from the experimental results in the table above, the BiOCl photocatalyst prepared in example 1 has the most excellent photocatalytic performance, and the degradation rate of rhodamine B molecules reaches 100% when Led irradiates for 15 min; secondly, the BiOCl photocatalyst prepared in examples 6-8 has the degradation rate of rhodamine B molecules reaching 97% when Led irradiates for 15 min. Thus, the BiOCl photocatalyst prepared by adding 0.5mmol of polyethylene glycol 2000 to every 1mmol of bismuth nitrate pentahydrate, or adding 0.2mmol of polyethylene glycol 6000, polyethylene glycol 8000 or polyethylene glycol 10000 to every 1mmol of bismuth nitrate pentahydrate has the best catalytic activity.

The photocatalytic degradation reaction can not separate the adsorption of the catalyst on the organic dye, the adsorption is an important precondition for the photocatalytic degradation, and the rapid implementation of the photocatalytic reaction is promoted due to the high adsorption efficiency. Whether the LED lamp is used as a light source or the xenon lamp is used as a light source, the visible light photocatalytic degradation performance of the BiOCl powder catalyst prepared in the example 1 on RhB is far better than that of the BiOCl powder catalyst prepared in the comparative example 1.

The power of the xenon lamp is high, the light intensity is high, the photocatalytic degradation efficiency of the catalyst on RhB is higher under the action of the xenon lamp, but the LED lamp is a common light source in home life, and the catalyst shows outstanding photocatalytic performance under the action of the light source, so that the catalyst can be used for indoor degradation of organic pollutants. When a LED strip (white, 32W) was used for direct illumination, the BiOCl powder prepared in example 1 of the present invention completely degraded RhB to colorless within 15min, whereas the BiOCl powder prepared in comparative example 1 had only 72% of the degradation rate of RhB even when it was illuminated for 30min (see fig. 5 d).

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.