Visible light catalytic composite material as well as preparation method and application thereof

Abstract

The invention provides a visible light catalytic composite material and a preparation method and application thereof.The preparation method comprises the steps that bismuth oxyiodide, zinc acetate and a proper amount of deionized water are mixed and subjected to ultrasonic dispersion to form dispersion liquid, K4PTC is dissolved in a proper amount of deionized water to obtain a K4PTC solution, under the stirring condition, the K4PTC solution is dropwise added into the dispersion liquid, stirring is continuously conducted for 10-12 h, then centrifugation, washing and vacuum drying treatment are conducted, and BiOI / Zn-PTC is obtained; according to the preparation method, BiOI is introduced in the process of synthesizing the monomer Zn-PTC, so that in-situ one-step synthesis of the novel visible light catalytic composite material BiOI / Zn-PTC is realized; the addition of BiOI enables UV-vis of Zn-PTC to generate red shift, so that the BiOI / Zn-PTC has a visible light absorption range wider than that of a monomer. Moreover, due to the introduction of BiOI, the weak shoulder peak absorption of the Zn-PTC material at 550nm is compensated, and the separation of photo-induced electron-hole pairs of BiOI / Zn-PTC on a heterogeneous interface is successfully realized, so that the rapid in-situ recombination of electrons-holes in a band gap of a monomer catalytic material is avoided, and the migration of photo-induced carriers and the reduction of the band gap are facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterials, and particularly relates to a visible-light photocatalytic composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As one of the industrial raw materials used on a large scale, bisphenol A occupies an important position in the global production of polycarbonate plastics and epoxy resin plastics. In recent years, the development of downstream industries of polycarbonate and epoxy resin such as consumer electronics, new energy vehicles, optical media, wind turbine blades, and 5G industrial construction has driven the demand growth of bisphenol A. The annual global production of bisphenol A exceeds tens of millions of tons, and more than one million tons of bisphenol A is released into the surrounding environment. The migration of bisphenol A into the environment occurs in every link of the whole process of manufacturing, distributing, using, consuming, treating, and disposing of devices and products containing bisphenol A. Bisphenol A is classified as an endocrine-disrupting compound by the American Endocrine Society. When it enters the body, it will affect human estrogen, androgen, prostate, thyroid, neurodevelopment, and neuroendocrine systems, etc., and then induce various diseases. Therefore, adding an efficient removal process before the discharge of industrial wastewater from bisphenol A production is of great significance for cutting off the transformation and migration path of bisphenol A and reducing the environmental background value.

[0003] Compared with biodegradation, physical adsorption, etc., the photocatalytic advanced oxidation technology generates reactive oxygen species with high reactivity through photoexcitation to destroy the structure of pollutants, which is more convenient and efficient. In addition, photocatalytic oxidation can utilize natural light resources, so it is more green and sustainable. In the near-surface solar spectrum, the number of visible light photons is relatively large (44%) and the energy distribution is concentrated in a narrow wavelength range, which can effectively carry out photoreaction on weak-bond compounds to catalyze the formation of high-value-added compounds.

[0004] The existing related patents for photocatalytic degradation of bisphenol A pollution in water have a high removal rate but still a low rate; therefore, it is of great significance to design a more efficient visible-light catalyst for the degradation of bisphenol A water pollution. Summary of the Invention

[0005] Aiming at the above problems existing in the prior art, the present invention provides a visible-light photocatalytic composite material, a preparation method thereof, and an application thereof. By compounding bismuth oxyiodide (BiOI) with zinc perylene tetracarboxylate (Zn-PTC), a composite photocatalytic material with a simple preparation method, a higher degradation rate of bisphenol A under visible light, better stability, and recyclability is developed.

[0006] The specific content of the invention is as follows: In the first aspect, the present invention provides a preparation method of a visible-light photocatalytic composite material, and the preparation method of the composite material includes: Mix bismuth oxyiodide, zinc acetate and an appropriate amount of deionized water, and ultrasonically disperse them to form a dispersion. Add K 4 PTC to an appropriate amount of deionized water to obtain a K 4 PTC solution; the molar ratio of the zinc acetate to the K 4 PTC is 2:1; the molar ratio of the bismuth oxyiodide to the zinc acetate is 1:2 - 8:1; Under stirring conditions, add the K 4 PTC solution dropwise to the dispersion, and continue stirring for 10 - 12 h. After centrifugation, washing, and vacuum drying, the visible light catalytic composite material - BiOI / Zn-PTC is obtained.

[0007] Optionally, the bismuth oxyiodide is prepared by the following method: Dissolve the bismuth-containing soluble salt in ethylene glycol to form a first solution, and then add the first solution dropwise to the iodine-containing soluble salt solution, or add the iodine-containing soluble salt solution dropwise to the first solution. After continuous stirring for 10 - 12 h, it is obtained after centrifugation, washing, and drying.

[0008] Optionally, the bismuth-containing soluble salt is bismuth nitrate pentahydrate, bismuth sulfate, or bismuth chloride; The iodine-containing soluble salt is potassium iodide, sodium iodide, or magnesium iodide; The molar ratio of the bismuth-containing soluble salt to the iodine-containing soluble salt is 1:1.

[0009] Optionally, the volume ratio of the deionized water to the ethylene glycol is 1:1 - 4.

[0010] Optionally, the K 4 PTC is obtained by the following preparation method: Add perylene tetracarboxylic dianhydride to an alkaline hydrolyzing agent, mix to form a second solution, and transfer the second solution to a sealed polytetrafluoroethylene inner liner. Carry out a hydrothermal reaction at 100 - 150 °C to hydrolyze the perylene tetracarboxylic dianhydride and form a precipitate. After centrifugation, washing, and vacuum drying, K 4 PTC is obtained.

[0011] Optionally, the time of the hydrothermal reaction is 6 - 12 h.

[0012] Optionally, the washing includes: alternately washing with deionized water and ethanol 2 - 6 times, and the drying temperature is 40 - 100 °C.

[0013] In a second aspect, the present invention provides a visible light catalytic composite material, which is obtained by the preparation method described in the first aspect above.

[0014] In a third aspect, the present invention provides an application of a visible-light photocatalytic composite material, which is obtained by the preparation method described in the first aspect above. The visible-light photocatalytic composite material is used for the degradation of bisphenol A, a pollutant in water, driven by visible light; Under visible light illumination, the degradation efficiency of bisphenol A with an initial concentration of 20 ppm by 0.5 g / L of the visible-light photocatalytic composite material within 10 minutes is not less than 89%.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention provides a preparation method of a visible-light photocatalytic composite material. Bismuth oxyiodide, zinc acetate and an appropriate amount of deionized water are mixed and ultrasonically dispersed to form a dispersion. Potassium perylene tetracarboxylate (K 4 PTC) is dissolved in an appropriate amount of deionized water to obtain a K 4 PTC solution. Under stirring conditions, the K 4 PTC solution is added dropwise to the dispersion, and after continuous stirring for 10 - 12 h, it is centrifuged, washed and vacuum dried to obtain the visible-light photocatalytic composite material - BiOI / Zn-PTC.

[0016] In the present invention, by introducing BiOI during the synthesis of Zn-PTC, a new visible-light photocatalytic composite material BiOI / Zn-PTC is in-situ synthesized in one step, and the preparation method is simple. The addition of BiOI causes a red shift in the UV-vis of Zn-PTC, making the BiOI / Zn-PTC visible-light photocatalytic composite material have a wider visible-light absorption range than the monomer Zn-PTC and the monomer BiOI. Moreover, the introduction of BiOI makes up for the weak shoulder peak absorption of the Zn-PTC material at 550 nm, and successfully realizes the separation of photo-generated electron-hole pairs at the heterojunction interface (BiOI and Zn-PTC) of the BiOI / Zn-PTC visible-light photocatalytic composite material, thereby avoiding the rapid in-situ recombination of electrons and holes in the band gaps of the monomer Zn-PTC and the monomer BiOI materials, which is helpful for the migration of photo-generated carriers and the narrowing of the band gap.

[0017] Furthermore, experiments have shown that, under the conditions of the same dosages of BiOI / Zn-PTC, monomeric Zn-PTC, and monomeric BiOI, and the same content of bisphenol A in the wastewater to be treated, under visible light (λ>420nm) irradiation, when the dosages of the BiOI / Zn-PTC composite material, monomeric Zn-PTC, and monomeric BiOI are all 0.5 g / L, the initial concentration of bisphenol A is 20 ppm, and the initial temperature is room temperature, the degradation performance of monomeric Zn-PTC for bisphenol A under light irradiation is poor, and only about 47% of bisphenol A can be removed after 40 minutes of light irradiation; for monomeric BiOI-L and BiOI-F, after 40 minutes of visible light irradiation, the removal rates of BPA are 98% and 93% respectively; while for the BiOI / Zn-PTC composite material provided in the examples of the present invention, after 10 minutes of light irradiation, the degradation efficiency of bisphenol A is as high as 89%. Compared with the monomeric Zn-PTC photocatalytic nanomaterial, the BiOI / Zn-PTC composite material has a wider visible light absorption range and stronger degradation ability for bisphenol A.

[0018] In addition, in 5 consecutive degradation experiments, the degradation efficiency of bisphenol A by the BiOI / Zn-PTC composite material provided in the present invention remains above 89%, proving that the BiOI / Zn-PTC composite material has good stability, can be recycled, and has potential application value in the field of wastewater purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 Shows the flowchart of the preparation method of the Zn-PTC / BiOI composite material provided in Embodiment 1 of the present invention; Figure 2 Shows the X-ray diffraction pattern of the photocatalytic material prepared in the embodiments of the present invention; Figure 3 Shows the SEM image of the photocatalytic material prepared in the embodiments of the present invention; Figure 4 Shows the UV diffuse reflectance spectrum of the photocatalytic material provided in the embodiments of the present invention; Figure 5 Shows the N 2 adsorption-desorption isotherm diagram; Figure 6Shows the performance comparison diagram of the photocatalytic material provided by the embodiment of the present invention for degrading bisphenol A; Figure 7 Shows the performance comparison diagram of the photocatalytic composite material provided by the embodiment of the present invention for degrading bisphenol A; Figure 8 Shows the stable photocatalytic performance of the photocatalytic composite material provided by the embodiment of the present invention. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other existing technologies falls within the protection scope of the present invention. And all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0022] For the technologies, methods, and equipment known to those of ordinary skill in the relevant fields, detailed discussions may not be made, but under appropriate circumstances, the said technologies, methods, and equipment should be regarded as part of the authorization specification.

[0023] In the description of the present invention, it should be understood that using terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meanings, so they cannot be understood as limiting the protection scope of the present invention.

[0024] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025]

[0026] ​When Zn-PTC is used as a catalyst for visible-light catalytic decomposition of bisphenol A, the π-π stacking caused by the perylene group makes the perylene-based supramolecular material generally have strong absorption in the visible-light region of 400-600 nm. However, Zn 2+ coordination with the perylene-based carboxylic acid group (PTC - ), induces the molecules to be arranged orderly in three-dimensional space, reduces the π-π stacking effect of the perylene group, and makes the strong visible-light absorption band of Zn-PTC narrow to the region of 400-520 nm. At the same time, due to the charge transfer effect of photoelectrons transferring from Zn 2+ to PTC - ligand, a shoulder peak centered at about 550 nm appears in the absorption spectrum of Zn-PTC. This results in low utilization rate of visible light by Zn-PTC, high recombination probability of photo-generated electron-hole pairs, and poor catalytic degradation efficiency for bisphenol A, severely limiting its application prospects.

[0027] Bismuth oxyiodide is a p-type semiconductor with a layered structure and high chemical stability. It has a small band gap, strong absorption and response to visible light, and is a promising visible-light-responsive photocatalyst. However, the recombination of photo-generated electron-hole pairs in pure-phase bismuth oxyiodide is relatively fast, and its actual photocatalytic performance is still not satisfactory.

[0028] Through further research on Zn-PTC and bismuth oxyiodide, the present invention finds that the two can be compounded through a simple synthesis method, so as to achieve the purpose of developing a composite catalyst material with a simple preparation method, higher degradation rate of bisphenol A under visible light, better stability and reusability. The specific implementation content of the present invention is as follows: In the first aspect, the present invention provides a preparation method of a visible-light catalytic composite material, Figure 1 shows the flow chart of the preparation method of the visible-light catalytic composite material provided by the embodiment of the present invention. As Figure 1 shown, the preparation method of the composite material includes: S1. Mix bismuth oxyiodide, zinc acetate and an appropriate amount of deionized water, and ultrasonically disperse to form a dispersion. Dissolve K 4 PTC in an appropriate amount of deionized water to obtain a K 4 PTC solution; the molar ratio of the zinc acetate to K 4 PTC is 2:1; the molar ratio of BiOI to the zinc acetate is 1:2 - 8:1; S2. Under stirring conditions, drop the K 4 PTC solution into the dispersion, and continue stirring for 10 - 12 h. After centrifugation, washing and vacuum drying, the visible-light catalytic composite material - BiOI / Zn-PTC is obtained.

[0029] In the embodiments of the present invention, a strategy of simultaneously preparing Zn-PTC and compounding BiOI with Zn-PTC is adopted, which greatly shortens the preparation process of the visible-light catalytic composite material - BiOI / Zn-PTC and simplifies the preparation process. Moreover, during the preparation process, by controlling the molar ratio of zinc acetate and K 4 PTC, as well as the molar ratio of BiOI to zinc acetate, the proportions of BiOI and Zn-PTC in the visible-light catalytic composite material are controlled, and finally a visible-light catalytic composite material - BiOI / Zn-PTC with ideal photocatalytic degradation effect is obtained.

[0030] It should be noted that in the BiOI / Zn-PTC synthesis reaction system provided by the present invention, the molar ratio of zinc acetate and K 4 PTC is controlled to be 2:1. A high concentration of Zn 2+ can provide more condensation nuclei, thereby obtaining large lamellar Zn-PTC; if the Zn 2+ concentration is low and the temperature during the synthesis process is low, the low wafer growth rate makes Zn-PTC in a flower ball shape, which is not conducive to increasing the specific surface area of the BiOI / Zn-PTC visible-light catalytic composite material and affects its catalytic performance.

[0031] In some embodiments, BiOI, as one of the reaction raw materials, can be obtained commercially or through the following preparation steps: Dissolve the bismuth-containing soluble salt in ethylene glycol to form a first solution, and then drop the first solution into the iodine-containing soluble salt solution, or drop the iodine-containing soluble salt solution into the first solution. After continuously stirring for 10 - 12 h, it is obtained after centrifugation, washing and drying.

[0032] It should be noted that based on the selection of the mixing method of the first solution and the iodine-containing soluble salt solution, the structural morphology of the obtained BiOI is different. When choosing to drop the first solution into the iodine-containing soluble salt solution, the obtained bismuth oxyiodide is flower ball-shaped bismuth oxyiodide BiOI-F; when choosing to drop the iodine-containing soluble salt solution into the first solution, the obtained bismuth oxyiodide is flake-shaped bismuth oxyiodide BiOI-L.

[0033] Among them, the bismuth-containing soluble salt can be selected from bismuth nitrate pentahydrate, bismuth sulfate or bismuth chloride; the iodine-containing soluble salt can be selected from potassium iodide, sodium iodide or magnesium iodide; the molar ratio of the bismuth-containing soluble salt to the iodine-containing soluble salt is 1:1. For the stirring method in this embodiment, magnetic stirring is preferably used, and there is no special requirement for the stirring speed, and 200 - 600 r / min can be selected. There is no clear requirement for the centrifugation speed in this embodiment, and it is greater than 7000 r / min. The volume ratio of deionized water to ethylene glycol is controlled at 1:1 - 4.

[0034] In some embodiments, K, one of the reaction raw materials 4 PTC, which can be obtained commercially or through the following preparation steps: Add perylene tetracarboxylic dianhydride to an alkaline hydrolyzing agent, mix to form a second solution, and transfer the second solution to a sealed polytetrafluoroethylene inner liner. Control the hydrothermal temperature at 100 - 150 °C to hydrolyze perylene tetracarboxylic dianhydride and form a precipitate. After centrifugation, washing, and vacuum drying, K 4 PTC is obtained. In this process, perylene tetracarboxylic dianhydride is hydrolyzed by an alkaline hydrolyzing agent, causing the acid anhydride bond to break and obtaining a perylene tetracarboxylate ligand. The alkaline hydrolyzing agent can be selected from sodium hydroxide solution or potassium hydroxide solution; during operation, perylene tetracarboxylic dianhydride and potassium hydroxide / sodium hydroxide can be dissolved in water, and the resulting mixture is stirred and then transferred to a sealed polytetrafluoroethylene inner liner. The hydrothermal treatment promotes the hydrolysis process, and the hydrothermal heating time is controlled at 6 - 12 h; after cooling, the hydrolyzed solution is poured into ethanol to form a bright yellow precipitate. After centrifugation, it is washed 2 - 6 times alternately with ethanol and water to remove excess hydroxide ions. The obtained precipitate is vacuum dried, and the resulting solid is ground to obtain potassium perylene tetracarboxylate (K 4 PTC).

[0035] It should be noted that the washing treatment method involved in the embodiments of the present invention is: washing 2 - 6 times alternately with deionized water and ethanol, and the drying treatment temperature is 60 - 100 °C.

[0036] In the present invention, by introducing BiOI during the synthesis of Zn - PTC, a new visible - light - catalytic composite material BiOI / Zn - PTC is synthesized in - situ in one step, and the preparation method is simple. The addition of BiOI causes the UV - vis of Zn - PTC to undergo a red - shift, making the BiOI / Zn - PTC visible - light - catalytic composite material have a wider visible - light absorption range than monomeric Zn - PTC and monomeric BiOI. Moreover, the introduction of BiOI makes up for the weak shoulder peak absorption of the Zn - PTC material at 550 nm, and successfully realizes the separation of photo - generated electron - hole pairs at the heterojunction interface (BiOI and Zn - PTC) of the BiOI / Zn - PTC visible - light - catalytic composite material, thereby avoiding the rapid in - situ recombination of electrons and holes in the band gaps of monomeric Zn - PTC and monomeric BiOI materials, which is conducive to the migration of photo - generated carriers and the narrowing of the band gap.

[0037] In a second aspect, the present invention provides a visible - light - catalytic composite material obtained by the preparation method described in the first aspect above.

[0038] In a third aspect, the present invention provides an application of a visible light catalytic composite material in the degradation of bisphenol A. The visible light catalytic composite material is obtained by the preparation method described in the first aspect above, and the visible light catalytic composite material is used for the degradation of the pollutant bisphenol A in water under visible light irradiation; Under visible light irradiation, the degradation efficiency of bisphenol A with an initial concentration of 20 ppm by 0.5 g / L of the visible light catalytic composite material within 10 min is not less than 89%.

[0039] Experiments have proved that when the dosages of BiOI / Zn-PTC, monomer Zn-PTC, and monomer BiOI are the same, and the content of bisphenol A in the sewage to be treated is the same, under visible light (λ>420nm) irradiation, the concentrations of BiOI / Zn-PTC visible light catalytic composite material, monomer Zn-PTC, and monomer BiOI are all 0.5 g / L, the initial concentration of bisphenol A is 20 ppm, and the initial temperature is room temperature. The degradation performance of monomer Zn-PTC on bisphenol A under light irradiation is poor, and only about 47% of bisphenol A can be removed after 40 min of light irradiation; for monomer BiOI-L and BiOI-F, after 40 min of visible light irradiation, the removal rates of BPA are 98% and 93% respectively; while the BiOI / Zn-PTC visible light catalytic composite material provided in the embodiment of the present invention has a degradation efficiency of up to 89% for bisphenol A after 10 min of light irradiation; compared with the monomer Zn-PTC photocatalytic nanomaterial, the BiOI / Zn-PTC visible light catalytic composite material has a wider visible light absorption range and stronger degradation ability for bisphenol A.

[0040] In addition, the degradation efficiency of bisphenol A by the BiOI / Zn-PTC visible light catalytic composite material provided in the present invention remains above 89% in 5 consecutive degradation experiments, proving that the BiOI / Zn-PTC composite material has good stability, can be recycled, and has potential application value in the field of sewage purification.

[0041] To make those skilled in the art understand the present application more clearly, the following examples are now used to describe in detail a visible light catalytic composite material, a preparation method, and an application thereof described in the present application.

[0042] The zinc acetate involved in the examples is zinc acetate dihydrate. All reagents can be used without further purification. All experiments use deionized water.

[0043] Example 1 Preparation of flower-like bismuth oxyiodide BiOI-F 485 mg of bismuth nitrate pentahydrate (1.0 mmol) was dissolved in 50 mL of ethylene glycol to obtain a first solution. 166 mg of KI (1.0 mmol) was dissolved in 50 mL of deionized water to obtain a KI solution, and it was stirred for 20 min. Then the first solution was added dropwise to the KI solution. At the moment when the first solution was dropped in, the solution turned dark orange. Continuing to add drops, an orange-red precipitate appeared. As the dropping continued, the color of the turbid solution became lighter and finally remained orange-red unchanged. Stirring was continued overnight. After the turbid solution was allowed to stand and settle, it was centrifuged at 7000 rpm, washed alternately with deionized water and ethanol three times each. The obtained solid was dried at 60 °C and ground to obtain orange-red powder, flower-shaped bismuth oxyiodide BiOI-F.

[0044] Example 2 Preparation of flaky bismuth oxyiodide BiOI-L 485 mg of bismuth nitrate pentahydrate (1.0 mmol) was dissolved in 50 mL of ethylene glycol to obtain a first solution. 166 mg of KI (1.0 mmol) was dissolved in 50 mL of deionized water to obtain a KI solution, and it was stirred for 20 min. Then the KI solution was added dropwise to the first solution. At the moment when it was dropped in, the solution turned dark orange. Continuing to add drops, an orange-red precipitate appeared. As the dropping continued, the color of the turbid solution became lighter and finally remained orange-red unchanged. Stirring was continued overnight. After the turbid solution was allowed to stand and settle, it was centrifuged at 7000 rpm, washed alternately with deionized water and ethanol three times each. The obtained solid was dried at 60 °C and ground to obtain orange-red powder, flaky bismuth oxyiodide BiOI-L.

[0045] Example 3 200 mg of the dried BiOI-F powder from Example 1 and 28 mg of zinc acetate were taken and dispersed in 50 mL of deionized water. After ultrasonic dispersion for 30 min, it was stirred for 30 min to form a dispersion; 37 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain a K 4 PTC solution, which was added dropwise to the dispersion (the molar ratio of zinc acetate and K 4 PTC was about 2:1, and the molar ratio of BiOI to zinc acetate was 4.46:1). After stirring overnight, it was dried in vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-F to Zn-PTC of 4:1, named BiOI-F / Zn-PTC 4-1 .

[0046] Example 4 200 mg of the dried BiOI-F powder from Example 1 and 55 mg of zinc acetate were taken and dispersed in 50 mL of deionized water. After ultrasonic dispersion for 30 min, it was stirred for 30 min to form a dispersion; 73 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain a K 4PTC solution, which was dropped into the dispersion (the molar ratio of zinc acetate to K 4 The molar ratio of PTC was about 2:1, and the molar ratio of BiOI to zinc acetate was 2.27:1). After stirring overnight, it was dried in vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-F to Zn-PTC of 2:1, named BiOI-F / Zn-PTC 2-1 .

[0047] Example 5 Take 200 mg of the dried BiOI-F powder from Example 1 and 110 mg of zinc acetate in 50 mL of deionized water. After ultrasonic dispersion for 30 min, stir for 30 min to form a dispersion; take 145 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain K 4 PTC solution, which was dropped into the dispersion (the molar ratio of zinc acetate to K 4 The molar ratio of PTC was about 2:1, and the molar ratio of BiOI to zinc acetate was 1.13:1). After stirring overnight, it was dried in vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-F to Zn-PTC of 1:1, named BiOI-F / Zn-PTC 1-1 .

[0048] Example 6 Take 100 mg of the dried BiOI-F powder from Example 1 and 110 mg of zinc acetate in 50 mL of deionized water. After ultrasonic dispersion for 30 min, stir for 30 min to form a dispersion; take 145 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain K 4 PTC solution, which was dropped into the dispersion (the molar ratio of zinc acetate to K 4 The molar ratio of PTC was about 2:1, and the molar ratio of BiOI to zinc acetate was 0.57:1). After stirring overnight, it was dried in vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-F to Zn-PTC of 1:2, named BiOI-F / Zn-PTC 1-2 .

[0049] Example 7 Take 100 mg of the dried BiOI-F powder from Example 1 and 220 mg of zinc acetate in 50 mL of deionized water. After ultrasonic dispersion for 30 min, stir for 30 min to form a dispersion; take 145 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain K 4The PTC solution was added dropwise to the dispersion. After stirring overnight, it was dried under vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-F to Zn-PTC of 1:4, named BiOI-F / Zn-PTC 1-4 .

[0050] Example 8 Take 200 mg of the dried BiOI-L powder from Example 2 and 55 mg of zinc acetate in 50 mL of deionized water. After ultrasonic dispersion for 30 min, stir for 30 min to form a dispersion; take 73 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain K 4 PTC solution, which was added dropwise to the dispersion (the molar ratio of zinc acetate to K 4 PTC was about 2:1, and the molar ratio of BiOI to zinc acetate was 2.27:1). After stirring overnight, it was dried under vacuum to obtain a visible-light photocatalytic composite material with a mass ratio of BiOI-L to Zn-PTC of 2:1, named BiOI-L / Zn-PTC 2-1 .

[0051] Example 9 Take 28 mg of zinc acetate in 50 mL of deionized water; take 37 mg of K 4 PTC was dissolved in 50 mL of deionized water to obtain K 4 PTC solution, which was added dropwise to the zinc acetate solution. After stirring overnight, it was dried under vacuum to obtain Zn-PTC.

[0052] Figure 2 The X-ray diffraction patterns of the photocatalytic materials prepared in the examples of the present invention are shown. As Figure 2 shown, the XRD pattern of Zn-PTC matches the Zn-PTC with the orthorhombic Pbam space group; both BiOI-F and BiOI-L synthesized in different dropping directions correspond well to tetragonal bismuth oxyiodide (JCPDS No. 73–2062); in the XRD pattern of the BiOI / Zn-PTC 4-1 photocatalytic composite material, the characteristic peaks of BiOI, which account for the main proportion, are completely retained without displacement broadening; while the characteristic peak signal of the (001) crystal plane of Zn-PTC is relatively weak under the cover of BiOI; the presence of the characteristic peaks of the two monomer materials and no other impurity peaks indicate that the introduction of BiOI does not affect the Zn 2+ and COO - coordination synthesis process. The sharp characteristic peaks in the monomers and composite materials indicate that the synthesized materials all have high crystallinity and purity.

[0053] Figure 3The SEM images of the photocatalytic materials prepared in the embodiments of the present invention are shown. Among them, (a) and (b) are the SEM images of BiOI-F at different sizes, (c) and (d) are the SEM images of Zn-PTC at different sizes, and (e) and (f) are the SEM images of BiOI-F / Zn-PTC 4-1 ; as Figure 3 shown in (a) and (b), BiOI-F is formed by the interpenetration of wafers with a diameter of 700 nm to form a flower-like structure with a diameter of 1-2 µm. The large open cavities between the wafers will increase the number of internal refractions of photons, thus helping to improve the light absorption performance of the material; the thickness of the intersecting wafers (10-30 nm) is close to the exciton migration distance, which will increase the recombination probability of carriers on the surface while promoting the migration of photo-generated carriers from the bulk to the surface; Figure 3 (c) and (d) show the large-plane spindle-shaped sheet structure of Zn-PTC with a length and width of 12*7 µm. Zn 2+ The strong coordination between Zn and the organic ligand and the weak coordination with adjacent water molecules enable the molecules to continuously extend and grow in the two-dimensional direction under the drive of π-π interaction to form large layers, which is verified by the strong characteristic peak signal of the (001) crystal plane in the XRD spectrum shown Figure 2 in. Figure 3 (e) and (f) show that the introduction of BiOI hinders the layer extension of Zn-PTC, and at the same time increases the risk of fracture of the large plane of Zn-PTC, thus reducing the layer size; in addition, some unstable wafers of the BiOI-F flower ball fall off during the composite process and are distributed in the large layers of Zn-PTC. The interpenetrating wafers enable BiOI-F to be embedded inside or on the periphery of the perylene ring layers of Zn-PTC. The direct embedding of the two is helpful for the carrier migration process.

[0054] Figure 4 The UV diffuse reflection spectra of the photocatalytic materials provided in the embodiments of the present invention are shown. Among them, BiOI-F is the photocatalytic material prepared in Example 1, BiOI-L is the photocatalytic material prepared in Example 2, BiOI-F / Zn-PTC 4-1 is the photocatalytic composite material prepared in Example 3, BiOI-L / Zn-PTC 2-1 is the photocatalytic composite material prepared in Example 8, and Zn-PTC is the photocatalytic material prepared in Example 9. As Figure 4 shown, the good light absorption characteristics determine the ability of the material to generate photo-generated carriers to a certain extent. In Zn-PTC, the π-π stacking caused by the perylene group makes the perylene-based supramolecular material generally have strong absorption in the visible light region of 400-600 nm. However, Zn 2+ and the perylene-based carboxylic acid group (PTC -The coordination-induced molecules between them are arranged orderly in three-dimensional space, reducing the π-π stacking effect of the perylene group, and narrowing the strong visible light absorption band of Zn-PTC to the 400-520 nm region; meanwhile, photoelectrons transfer from Zn 2+ to PTC - ligand transfer charge transfer effect, and a shoulder peak centered at about 550 nm appears in the absorption spectrum of Zn-PTC. The light absorption edges of BiOI-F and BiOI-L with different morphologies are at 650 nm, and the light absorption edge of Zn-PTC is at 700 nm. The combination of the two monomer materials perfectly integrates the light absorption advantages of both, extending the light absorption edge by 100 nm in the red shift direction and compensating for the weak shoulder peak absorption of the Zn-PTC material at 550 nm. The good light absorption performance makes the photocatalytic performance of the composite material better than that of the monomer material.

[0055] Figure 5 shows the N 2 adsorption-desorption isotherm diagram of the photocatalytic material provided by the embodiment of the present invention, where BiOI-F is the photocatalytic material prepared in Example 1, and BiOI-F / Zn-PTC 4-1 is the photocatalytic composite material prepared in Example 3, and Zn-PTC is the photocatalytic material prepared in Example 9. As Figure 5 shown, in the figure, the N 4-1 adsorption-desorption isotherms of the monomer Zn-PTC, the monomer BiOI-F, and the composite material BiOI-F / Zn-PTC 2 of the two belong to typical type III isotherms, which are concave downward throughout the range and have no inflection points, indicating that the monomer and the composite material have partial mesoporous structures. The specific surface areas of the monomer Zn-PTC, the monomer BiOI-F, and the photocatalytic composite material BiOI-F / Zn-PTC 4-1 are 7.36, 22.12, and 25.06 m 2 ·g -1 in turn. The specific surface area of the photocatalytic composite material BiOI-F / Zn-PTC 4-1 is higher than that of the constituent monomers, which is attributed to the introduction of BiOI-F during the synthesis of Zn-PTC. The physical partition formed hinders the growth of Zn-PTC in the direction of the large plane, and the small size and cross-sectional area observed in the morphology increase the micropore distribution of the composite material. This enables the BiOI-F / Zn-PTC 4-1 photocatalytic composite material to have good adsorption and photocatalytic synergy ability.

[0056] Experimental Example 1 This experimental example is used to verify the degradation performance of bisphenol A by the Zn-PTC / BiOI, BiOI, and Zn-PTC photocatalytic nanomaterials prepared in Example 1, Example 2, and Example 3.

[0057] (1) Photocatalytic activity evaluation: The visible-light photocatalytic performance of the synthesized materials was evaluated through bisphenol A (BPA) degradation experiments. The catalytic reaction used a 300 W xenon lamp (λ>420 nm) as the visible light source, and a cut-off filter was used to filter out light with wavelengths below 420 nm, with an average intensity of 100 mW / cm 2 , and the temperature of the reaction system was controlled at a constant 25 °C for a single reaction.

[0058] According to the experimental purpose, a mixed system of BPA with an initial concentration of 20 ppm and 0.5 g / L BiOI-F / Zn-PTC 4-1 photocatalytic composite material was used for the photoreaction experiment. Before the photoreaction, dark adsorption equilibrium was carried out for 30 min. After illumination, 1 mL of the reaction solution was taken at certain intervals and passed through a 0.25 µm cellulose acetate filter membrane. The filtrate was measured for the peak signal of BPA by liquid chromatography at a detection wavelength of 227 nm. Each group of experiments was designed with three parallels. The BPA degradation curve was obtained by measuring the ratio of the real-time concentration / initial concentration (C / C 0 ), and a trend line was made against time. The photocatalytic degradation experimental processes for other pollutants and different reaction conditions were similar to the BPA degradation process. The calculation formula for the degradation rate η of bisphenol A is: η = (C 0 / C t ) / C 0 × 100% where C 0 and C t are the initial concentration of BPA and the concentration after illumination for t hours, respectively (2) Continuous degradation experiment: After the first degradation reaction was completed, the petri dish containing the BiOI-F / Zn-PTC 4-1 photocatalytic composite material was dried at 60 °C for 0.5 hours, and then placed back into the reactor for the next bisphenol A removal reaction. Except for the material, the remaining reaction conditions were the same as the first time; after the second reaction was completed, the above steps were repeated for the fifth degradation experiment.

[0059] To further illustrate the excellent performance of the BiOI-F / Zn-PTC photocatalytic composite material prepared by the present invention, which has high visible light utilization rate and high degradation rate of bisphenol A, analysis will be carried out in combination with specific drawings.

[0060] Figure 6Shows the performance comparison chart of the photocatalytic material provided by the embodiment of the present invention for degrading bisphenol A. Among them, BiOI-F is the photocatalytic material prepared in Example 1, BiOI-L is the photocatalytic material prepared in Example 2, Bi-F / Zn 4-1 is the BiOI-F / Zn-PTC 4-1 photocatalytic composite material prepared in Example 3, Bi-L / Zn 2-1 is the BiOI-L / Zn-PTC 2-1 photocatalytic composite material prepared in Example 8, Zn-PTC is the photocatalytic material prepared in Example 9, Photodegradation is used as the blank control group, and the direct photocatalytic degradation performance of BPA under the condition of no catalyst is investigated; the results show that under the visible light direct irradiation on the time scale of 40 min of illumination, the control group hardly degrades BPA. The degradation performance of Zn-PTC on BPA under illumination is poor (47%), and the removal rates of BiOI-L and BiOI-F on BPA under visible light illumination for 40 min are 98% and 93% respectively. By compounding BiOI with Zn-PTC, the catalytic efficiency of the whole system is improved, and the comparison monomer reaction time is greatly shortened. BiOI-L / Zn-PTC 2-1 and BiOI-F / Zn-PTC 4-1 can achieve high-efficiency photocatalytic removal efficiencies of 89% (10 min) and 99% (20 min) in the same illumination system.

[0061] Figure 7 Shows the performance comparison chart of the photocatalytic composite material provided by the embodiment of the present invention for degrading bisphenol A. Among them, Bi-F / Zn 4-1 is the BiOI-F / Zn-PTC 4-1 photocatalytic composite material prepared in Example 3, Bi-F / Zn 2-1 is the BiOI-F / Zn-PTC 2-1 photocatalytic composite material prepared in Example 4, Bi-F / Zn 1-1 is the BiOI-F / Zn-PTC 1-1 photocatalytic composite material prepared in Example 5, Bi-F / Zn 1:2 is the BiOI-F / Zn-PTC 1:2 photocatalytic composite material prepared in Example 6, Bi-F / Zn 1:4 is the BiOI-F / Zn-PTC 1:4 photocatalytic composite material prepared in Example 7. As Figure 7 shown, with the increase of the compounding ratio of BiOI-F, the degradation efficiency of the catalyst on BPA gradually increases. When the compounding ratio of BiOI-F and Zn-PTC is 4:1, the composite material Bi-F / Zn 4-1The photocatalytic removal rate of BPA reached 97.2% within 20 min. Continuing to increase the proportion of BiOI-F, excessive BiOI-F will cover the surface of Zn-PTC, which will hinder the π-π interaction of the perylene ring plane and the adsorption of BPA. At the same time, the decrease in the proportion of Zn-PTC leads to the reduction of the electron delocalized acceptor, and the separation performance of photogenerated carriers becomes weaker.

[0062] Figure 8 The stable photocatalytic performance of the photocatalytic composite provided by the embodiment of the present invention is shown. As Figure 8 shown, after five cycles, the high-efficiency removal effect of 89% can still be maintained. Starting from the third cycle experiment, the final catalytic effect of the catalyst slowly weakens, and the 40-min catalytic effect of the material decreases to 89% after five cycles. It is speculated that due to BiOI-F / Zn-PTC 4-1 The spherical BiOI embedded at the edge of the plate has a large spatial volume resistance. After mechanical stirring and heat drying during the reaction, part of the edge BiOI flowers fall off, resulting in the weakening of the catalytic effect of the material. However, the BiOI wafers embedded inside Zn-PTC can still maintain the photocatalytic performance of the material.

[0063] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0064] For the method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0065] The above has introduced in detail a visible light catalytic composite material, a preparation method and an application thereof provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for preparing a visible light catalytic composite material, characterized in that: The preparation method of the composite material comprises: Mixing bismuth iodide and zinc acetate with an appropriate amount of deionized water, performing ultrasonic dispersion to form a dispersion, and dissolving K4PTC in an appropriate amount of deionized water to obtain a K4PTC solution; the molar ratio of the zinc acetate to K4PTC is 2:1; the molar ratio of the bismuth iodide to the zinc acetate is 1:2-8:1; Under stirring conditions, the K4PTC solution is added dropwise to the dispersion, and the mixture is stirred for 10-12 hours, and then centrifuged, washed, and vacuum dried to obtain the visible light catalytic composite material—BiOI / Zn-PTC.

2. The method for preparing the visible light catalytic composite material according to claim 1, characterized in that: The bismuth iodide is prepared by the following method: A soluble salt containing bismuth is dissolved in ethylene glycol to form a first solution, and then the first solution is added dropwise to a soluble salt solution containing iodine, or the soluble salt solution containing iodine is added dropwise to the first solution, and the mixture is stirred for 10-12 hours, and then centrifuged, washed, and dried to obtain the solution.

3. The method for preparing the visible light catalytic composite material according to claim 2, characterized in that: The soluble salt containing bismuth is bismuth nitrate pentahydrate, bismuth sulfate or bismuth chloride; The iodine-containing soluble salt is potassium iodide, sodium iodide or magnesium iodide; The molar ratio of the soluble salt containing bismuth to the soluble salt containing iodine is 1:

1.

4. The method for preparing the visible light catalytic composite material according to claim 2, characterized in that: The volume ratio of the deionized water to the ethylene glycol is 1:1-4.

5. The method for preparing the visible light catalytic composite material according to claim 1, characterized in that: The K4PTC is obtained by the following preparation method: Perylene tetracarboxylic anhydride is added to an alkaline hydrolyzing agent, mixed to form a second solution, and the second solution is transferred to a sealed polytetrafluoroethylene liner, and a hydrothermal reaction is carried out at 100-150° C. to hydrolyze the perylene tetracarboxylic anhydride and generate a precipitate. After centrifugation, washing, and vacuum drying, K4PTC is obtained.

6. The method for preparing the visible light catalytic composite material according to claim 5, characterized in that: The alkaline hydrolyzing agent is a sodium hydroxide solution or a potassium hydroxide solution; The hydrothermal reaction time is 6 to 12 h.

7. The method for preparing the visible light catalytic composite material according to claim 1, characterized in that: The washing comprises: washing with deionized water and ethanol alternately for 2-6 times, and the drying temperature is 40-100°C.

8. A visible light catalytic composite material, characterized in that: The visible light catalytic composite material is obtained by the preparation method described in any one of claims 1 to 7.

9. An application of a visible light catalytic composite material, characterized in that: The visible light catalytic composite material is obtained by the preparation method described in any one of claims 1 to 7, and the visible light catalytic composite material is used for visible light driven degradation of the pollutant bisphenol A in water.

10. The use according to claim 9, characterized in that: Under visible light, the degradation efficiency of 0.5 g / L of the visible light catalytic composite material for bisphenol A with an initial concentration of 20 ppm is not less than 89% within 10 minutes.

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