A graphene oxide / bi 12 TiO 20 Ultrasonic production method of composite materials and applications

Abstract

The application discloses a kind of Graphene Oxide / Bi 12 TiO 20 Preparation method and application of composite photocatalyst, to solve the existing Bi 12 TiO 20 Photocatalyst photo-generated carrier is fast, and it is easy to produce miscellaneous phase in preparation, leading to the technical problems such as low catalytic activity. First, Bi 12 TiO 20 Powder, such as Bi / Ti=4:1 or 6:1, then the Bi 12 TiO 20 Powder is compounded with single-layer GO dispersion under the action of ultrasonic wave. The Graphene Oxide / Bi 12 TiO 20 Composite photocatalyst prepared by the method is mixed with methyl orange (MO) solution under simulated visible light for 20 minutes, and the degradation rate of methyl orange reaches 98.2%, and the first-order kinetic reaction rate constant k value is 0.2167 min ‑1 , which can be widely applied in the field of visible light catalytic degradation of organic pollutants.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a semiconductor composite photocatalyst, particularly a graphene oxide / bismuth titanate (BAT) photocatalyst. 12 TiO 20 Ultrasonic preparation method of composite photocatalyst and its application in photocatalytic degradation of organic pollutants. Background Technology

[0002] With rapid industrialization, energy shortages and environmental pollution have become increasingly serious problems. Photocatalytic degradation of organic pollutants using solar energy is an advanced oxidation process (AOP) and is considered one of the effective ways to solve environmental and energy problems. Traditional photocatalysts, such as TiO2, have a wide band gap and are mainly activated under ultraviolet light, which accounts for less than 5% of sunlight, resulting in low solar energy utilization.

[0003] In recent years, bismuth-based photocatalytic materials have become a research hotspot due to their unique electronic structure and excellent visible light response. Among numerous bismuth-based composite oxides, bismuthite-based structural materials such as Bi0.05 are particularly noteworthy. 12 TiO 20 It has excellent visible light response and high photocatalytic activity.

[0004] However, Bi of a single component 12 TiO 20 Photocatalysts still suffer from the problem of rapid recombination rates of photogenerated electron-hole pairs, which limits further improvements in their quantum efficiency and photocatalytic activity. Furthermore, in the preparation of Bi... 12 TiO 20 During the process, especially in the hydrothermal method, slight changes in reaction conditions can easily introduce substances such as Bi₄Ti₃O₃. 12 Impurities such as impurities affect the purity and performance of the final product.

[0005] To suppress recombination of photogenerated carriers, researchers often employ material composite strategies. Graphene oxide (GO) is an ideal composite substrate due to its large specific surface area, excellent electrical conductivity, and electron mobility. Bi 12 TiO 20 When combined with GO, GO can be used as an electron acceptor and transport channel to effectively promote the separation of photogenerated charges, thereby improving photocatalytic efficiency.

[0006] Nevertheless, existing composite methods still present challenges. For example, the direct synthesis of GO / Bi using conventional hydrothermal methods... 12 TiO 20 When composite photocatalysts are used, GO and Bi 12 TiO20 Aggregation may occur between nanosheets, resulting in loose interfacial contact and affecting charge transfer efficiency. Meanwhile, effectively controlling or eliminating the interference of impurities on material properties during the composite process is also a pressing technical problem to be solved in this field.

[0007] Therefore, it is necessary to develop a method for preparing Graphene Oxide / Bi with a simple preparation process, tight interfacial contact, and high photocatalytic activity. 12 TiO 20 The method of composite photocatalysts has significant research and application value. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method that is simple to operate and can realize GO and Bi 12 TiO 20 Effective compounding significantly improves Bi 12 TiO 20 Graphene Oxide / Bi photocatalytic performance of the material 12 TiO 20 Preparation method of composite photocatalyst.

[0009] Another object of the present invention is to provide Graphene Oxide / Bi 12 TiO 20 Application of composite photocatalysts in the catalytic degradation of organic pollutants under visible light.

[0010] A Graphene Oxide / Bi 12 TiO 20 The ultrasonic preparation method for composite photocatalysts includes the following steps:

[0011] 1) Preparation of Bi 12 TiO 20 powder;

[0012] 2) Prepare Bi 12 TiO 20 The powder is added to water and ultrasonically treated to form a suspension.

[0013] 3) Preparation of graphene oxide (GO) dispersion;

[0014] 4) Add the monolayer graphene oxide (GO) suspension to the suspension in step 2), and sonicate the mixture again to obtain a composite suspension;

[0015] 5) The composite suspension was washed, filtered, and dried to obtain GO / Bi 12 TiO 20 Composite photocatalyst.

[0016] In step 1), Bi 12 TiO 20 The powder preparation steps are as follows:

[0017] S1: Weigh bismuth citrate and titanium dioxide, add 15 ml of deionized water, and prepare a hydroxyl oxide precipitate suspension containing titanium and bismuth;

[0018] S2: Add 20 ml of sodium hydroxide solution (mineralizing agent) with a concentration of 1-11 mol / L dropwise to the precipitate suspension of S1, controlling the dropping rate to 2-3 drops / second;

[0019] S3: Place the mixture of S2 in a reaction vessel, seal it, and perform hydrothermal treatment at 160~240℃ for 6~24h;

[0020] S4: After the hydrothermal reaction is complete, allow it to cool naturally, wash the reaction product repeatedly with deionized water and anhydrous ethanol, filter, and dry to obtain Bi. 12 TiO 20 powder.

[0021] In S1, the molar ratio of bismuth source to titanium source Bi / Ti is 4:1 or 6:1, wherein the bismuth source is bismuth citrate and the titanium source is titanium dioxide.

[0022] In step 2), an ultrasonic cell disruptor is used, with the following settings: ultrasonic frequency 40KHz, ultrasonic power 100W, and ultrasonic treatment for 15 minutes.

[0023] The preparation method of the GO suspension in step 3) is as follows: Take out 1 to 3 ml of monolayer GO dispersion, preferably the product of Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., CAS: 7440-44-0, add an appropriate amount of water, and use an ultrasonic cell disruptor with the ultrasonic frequency set to 40KHz and ultrasonic power set to 100W for 15 minutes.

[0024] A graphene oxide / Bi fabricated by ultrasound 12 TiO 20 The composite photocatalyst is prepared by any of the methods described above.

[0025] The prepared Graphene Oxide / Bi 12 TiO 20 The composite photocatalyst, as observed under a scanning electron microscope (SEM), consists of graphene oxide (GO) sheets tightly coating a portion of Bi. 12 TiO 20 Nanosheets.

[0026] The Graphene Oxide / Bi12 TiO 20 Composite photocatalysts are used to catalyze the degradation of organic pollutants under visible light.

[0027] The Graphene Oxide / Bi 12 TiO 20 The composite photocatalyst and methyl orange (MO) mixed solution, when irradiated under simulated visible light for 20 minutes, achieved a degradation rate of 98.2% for methyl orange (MO), with a first-order kinetic rate constant k of 0.2167 min. -1 .

[0028] The present invention has the following advantages:

[0029] The Graphene Oxide / Bi of this invention 12 TiO 20 An ultrasonic preparation method for composite photocatalysts was developed, where the high-frequency mechanical vibration of the ultrasonic method synergistically interacts with the oxidizing properties of GO, effectively eliminating the oxidation of Bi. 12 TiO 20 Trace amounts of Bi4Ti3O generated during material preparation 12 Impurities improve the phase purity of the material; at the same time, they make Bi... 12 TiO 20 Better dispersion makes Bi 12 TiO 20 The increased specific surface area further improves photocatalytic efficiency.

[0030] Through mechanical vibration, monolayer GO was used to achieve Bi 12 TiO 20 The nanosheets are tightly packed together. This tight interfacial contact greatly promotes the generation of photocharge from Bi. 12 TiO 20 The transfer to GO suppresses the recombination of photogenerated carriers, thereby improving photocatalytic efficiency.

[0031] This invention uses an ultrasonic method to prepare GO / Bi 12 TiO 20 The photocatalytic activity of the composite photocatalysts is much higher than that of Bi. 12 TiO 20 Materials, GO / Bi 12 TiO 20 The composite photocatalyst can achieve a degradation rate of 98% for methyl orange after 20 minutes of visible light irradiation, demonstrating high catalytic efficiency and application potential.

[0032] The process of this invention does not introduce other impurity ions, and GO / Bi can be obtained after ultrasonic oscillation. 12TiO 20 Composite materials.

[0033] The reaction medium of this invention is mainly deionized water, without the introduction of toxic or harmful organic solvents or surfactants; the selected raw materials include bismuth citrate, titanium dioxide, and graphene oxide. The method produces Graphene Oxide / Bi 12 TiO 20 Composite photocatalysts are chemically stable and environmentally friendly. They do not cause secondary pollution during the degradation of organic pollutants, and have good environmental safety and application prospects. Attached Figure Description

[0034] Figure 1 This is the GO / Bi prepared in Example 1 of the present invention. 12 TiO 20 X-ray diffraction (XRD) pattern of composite photocatalyst;

[0035] Figure 2 This is the GO / Bi prepared in Example 2 of the present invention. 12 TiO 20 Scanning electron microscope (SEM) image of the composite photocatalyst;

[0036] Figure 3 This is the GO / Bi prepared in Example 3 of the present invention. 12 TiO 20 The concentration change of methyl orange solution during photodegradation. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0040] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0041] The monolayer graphene oxide (GO) dispersion used in the following examples was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., with CAS number 7440-44-0.

[0042] Example 1:

[0043] A kind of GO / Bi 12 TiO 20 The ultrasonic preparation method for composite photocatalysts includes the following steps:

[0044] 1) Preparation of a hydroxyl oxide precipitate suspension containing titanium and bismuth;

[0045] 2) Transfer the reactants prepared in step 1) into the inner liner of the reactor, adjust the volume of the reactants in the inner liner to 90% of the inner liner volume with deionized water, and stir evenly.

[0046] 3) Place the inner liner of the reactor into the reactor, seal it, and perform hydrothermal treatment at 160℃ for 12 hours;

[0047] 4) After the hydrothermal reaction is complete, allow the reactor to cool naturally to room temperature. Wash the reaction product repeatedly with deionized water and anhydrous ethanol, filter, and dry to obtain Bi. 12 TiO 20 powder;

[0048] 5) Weigh the Bi prepared in step 4). 12 TiO 20 Add an appropriate amount of 25 ml of deionized water to the powder, put it into an ultrasonic cell disruptor, set the conditions to ultrasonic frequency 40 KHz and ultrasonic power 100 W, and sonicate for 15 min to make a suspension.

[0049] 6) Take 1 ml of monolayer GO dispersion, add 15 ml of deionized water, and use an ultrasonic cell disruptor with the ultrasonic frequency set to 40 kHz and ultrasonic power set to 100 W for 15 min to prepare a suspension.

[0050] 7) Add the GO suspension prepared in step 6) dropwise into the suspension prepared in step 5), place the mixture into an ultrasonic cell disruptor, set the conditions to ultrasonic frequency 40KHz and ultrasonic power 100W, and perform ultrasonic treatment for 15min to obtain a composite suspension.

[0051] 8) Wash the composite suspension prepared in step 7) repeatedly with deionized water and anhydrous ethanol, filter and dry to obtain GO / Bi 12 TiO 20 Composite photocatalyst;

[0052] In step 1), the preparation steps of the hydroxyl oxide precipitate suspension containing titanium and bismuth are as follows:

[0053] S1: Prepare a 5 mol / L sodium hydroxide solution;

[0054] S2: Weigh bismuth citrate and titanium dioxide in a molar ratio of 6:1. Add 15 ml of deionized water to the bismuth citrate and titanium dioxide. While stirring, add 20 ml of sodium hydroxide aqueous solution prepared in S1, controlling the dripping rate to 2-3 drops / second. After stirring thoroughly at room temperature, a hydroxyl oxide precipitate suspension containing titanium and bismuth is obtained.

[0055] Example 2:

[0056] A kind of GO / Bi 12 TiO 20 The ultrasonic preparation method for composite photocatalysts includes the following steps:

[0057] 1) Preparation of a hydroxyl oxide precipitate suspension containing titanium and bismuth;

[0058] 2) Transfer the reactants prepared in step 1) into the inner liner of the reactor, adjust the volume of the reactants in the inner liner to 70% of the inner liner volume with deionized water, and stir evenly.

[0059] 3) Place the inner liner of the reactor into the reactor, seal it, and keep it at 180℃ for 12 hours for hydrothermal treatment;

[0060] 4) After the hydrothermal reaction is complete, allow the reactor to cool naturally to room temperature. Wash the reaction product repeatedly with deionized water and anhydrous ethanol, filter, and dry to obtain Bi. 12 TiO 20 powder;

[0061] 5) Weigh the Bi prepared in step 4). 12 TiO 20 Add the powder to 25 ml of deionized water, place it in an ultrasonic cell disruptor, set the conditions to ultrasonic frequency 40KHz and ultrasonic power 100 W, and sonicate for 15 min to make a suspension.

[0062] 6) Take out 2 ml of monolayer GO dispersion, add 15 ml of deionized water, and use an ultrasonic cell disruptor with the ultrasonic frequency set to 40 kHz and ultrasonic power set to 100 W for 15 min.

[0063] The mixture is prepared into a suspension after ultrasonication.

[0064] 7) Add the GO suspension prepared in step 6) dropwise into the suspension prepared in step 5), place the mixture into an ultrasonic cell disruptor, set the conditions to ultrasonic frequency 40KHz and ultrasonic power 100 W, and sonicate again for 15 min to obtain a composite suspension.

[0065] 8) Wash the composite suspension prepared in step 7) repeatedly with deionized water and anhydrous ethanol, filter and dry to obtain GO / Bi 12 TiO 20 Composite photocatalyst;

[0066] In step 1), the preparation steps of the hydroxyl oxide precipitate suspension containing titanium and bismuth are as follows:

[0067] S1: Prepare a 5 mol / L sodium hydroxide solution;

[0068] S2: Weigh bismuth citrate and titanium dioxide in a molar ratio of 4:1. Add 15 ml of deionized water to the bismuth citrate and titanium dioxide, and add 20 ml of sodium hydroxide aqueous solution prepared in S1 while stirring. After stirring thoroughly at room temperature, a precipitate suspension of titanium and bismuth containing bismuth oxides is obtained.

[0069] Example 3:

[0070] A kind of GO / Bi 12 TiO 20 The ultrasonic preparation method for composite photocatalysts includes the following steps:

[0071] 1) Preparation of a hydroxyl oxide precipitate suspension containing titanium and bismuth;

[0072] 2) Transfer the reactants prepared in step 1) into the inner liner of the reactor, adjust the volume of the reactants in the inner liner to 90% of the inner liner volume with deionized water, and stir evenly.

[0073] 3) Place the inner liner of the reactor into the reactor, seal it, and keep it at 240℃ for 24 hours for hydrothermal treatment;

[0074] 4) After the hydrothermal reaction is complete, allow the reactor to cool naturally to room temperature. Wash the reaction product repeatedly with deionized water and anhydrous ethanol, filter, and dry to obtain Bi. 12 TiO 20 powder;

[0075] 5) Weigh the Bi prepared in step 4). 12 TiO 20Add the powder to 25ml of deionized water, place it in an ultrasonic cell disruptor, set the conditions to ultrasonic frequency 40KHz and ultrasonic power 100W, and sonicate for 15min to make a suspension.

[0076] 6) Take 3 ml of monolayer GO dispersion, add 15 ml of deionized water, and use an ultrasonic cell disruptor with the ultrasonic frequency set to 40 kHz and ultrasonic power set to 100 W. After ultrasonication for 15 min, a suspension is prepared.

[0077] 7) The GO suspension prepared in step 6) is added dropwise to the suspension prepared in step 5). The mixture is then placed in an ultrasonic cell disruptor and ultrasonically treated again with an ultrasonic frequency of 40KHz and an ultrasonic power of 100W to obtain a composite suspension.

[0078] 8) Wash the composite suspension prepared in step 7) repeatedly with deionized water and anhydrous ethanol, filter and dry to obtain GO / Bi 12 TiO 20 Composite photocatalyst;

[0079] In step 1), the preparation steps of the hydroxyl oxide precipitate suspension containing titanium and bismuth are as follows:

[0080] S1: Prepare a 5 mol / L sodium hydroxide solution;

[0081] S2: Weigh bismuth citrate and titanium dioxide in a molar ratio of 4:1. Add 15 ml of deionized water to the bismuth citrate and titanium dioxide, and add 20 ml of sodium hydroxide aqueous solution prepared in S1 while stirring. After stirring thoroughly at room temperature, a precipitate suspension of titanium and bismuth containing bismuth oxides is obtained.

[0082] Example 4: Photocatalytic Degradation Experiment

[0083] Catalytic degradation experiment of methyl orange solution: The catalyst dosage was 0.1 g per 100 ml of methyl orange solution, and the concentration of the methyl orange solution was 10. -5 After the methyl orange solution and catalyst were mixed evenly, the mixture was stirred in the dark for 30 minutes and then irradiated under simulated visible light. Samples were taken at regular intervals, centrifuged, and the absorbance of the solution was measured using a UV-Vis spectrophotometer.

[0084] The photocatalytic test used a 300W 15A xenon lamp with constant current, placed inside a dark chamber.

[0085] The GO / Bi prepared in Test Example 3 12 TiO 20 Photocatalytic performance of composite photocatalysts. (Reference) Figure 3The sample in this embodiment exhibited extremely high photocatalytic activity. Under simulated visible light for 20 minutes, the degradation rate of methyl orange (MO) reached 98.2%, with a first-order kinetic rate constant k of 0.2167 min. -1 This performance far exceeds that of Bi without GO composite in this invention. 12 TiO 20 The powder, with k = 0.0528 min -1 And other publicly reported Bi 12 TiO 20 Compared to other materials, it exhibits superior photocatalytic performance: for example, the nano-Bi prepared by Zhu et al. (Chemosphere, 2010, 78: 1350) shows superior photocatalytic performance. 12 TiO 20 Degrading more than 90% of Acid Orange 7 (AO7) requires 360 minutes, approximately 6 hours, with an optimal rate constant k of only 0.327 h. -1 That is, 0.00545 min -1 Baaloudj et al. (J. Cleaner Prod., 2022, 330: 129934) prepared Bi using the sol-gel method. 12 TiO 20 It takes 180 minutes, or about 3 hours, to degrade 94.9% of the antibiotic cefixime.

[0086] Moreover, compared to Bi reported in existing literature... 12 TiO 20 Compared to graphene-based composite materials, the samples in this embodiment also exhibit superior photocatalytic performance. For example, Guo et al. (Phys. Chem. Chem. Phys., 2014, 16, 2705) prepared Bi using a single-step solvothermal method. 12 TiO 20 -GR composite material. Its optimal sample (2% GR) exhibits a rate constant k of only 0.0244 min⁻¹ for the degradation of methyl orange (MO) under simulated sunlight. -1 Yu Wang's article, published in Science and Technology Innovation Herald, 2018, 15(5): 111, describes the preparation of Bi using an ultrasonic mixing method. 12 TiO 20 The GO composite material, however, showed that its optimal sample had a GO loading of only 10%, and the rate constant k for the degradation of Rhodamine B (RhB) was only 0.0072 min. -1Luo et al. (Diamond & Related Materials, 2022, 123, 108890) prepared reduced graphene oxide (Bi) using the sol-gel method and hydrothermal treatment. 12 TiO 20 The RGO composite material was used. The optimal sample had an RGO content of 3%, requiring 210 minutes to degrade Rhodamine B (RhB) to 98%, with a rate constant k of 0.01311 min. -1 In contrast, the GO / Bi prepared in this embodiment... 12 TiO 20 Composite photocatalysts exhibit superior photocatalytic performance and have more efficient practical application value in the photocatalytic degradation of organic dye wastewater.

[0087] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Graphene Oxide / Bi 12 TiO 20 The ultrasonic preparation method of composite photocatalyst is characterized by, Includes the following steps: 1) Preparation of Bi 12 TiO 20 powder; 2) Prepare Bi 12 TiO 20 The powder is added to water and ultrasonically treated to form a suspension. 3) Preparation of graphene oxide (GO) dispersion; 4) Add the monolayer graphene oxide (GO) suspension to the suspension in step 2), and sonicate the mixture again to obtain a composite suspension; 5) The composite suspension was washed, filtered, and dried to obtain GO / Bi 12 TiO 20 Composite photocatalyst.

2. The ultrasonic fabrication method according to claim 1, characterized in that, In step 1), Bi 12 TiO 20 The powder preparation steps are as follows: S1: Weigh bismuth citrate and titanium dioxide, add 15 ml of deionized water, and prepare a hydroxyl oxide precipitate suspension containing titanium and bismuth; S2: Add 20 ml of sodium hydroxide solution (mineralizing agent) with a concentration of 1-11 mol / L dropwise to the precipitate suspension of S1, controlling the dropping rate to 2-3 drops / second; S3: Place the mixture of S2 in a reaction vessel, seal it, and perform hydrothermal treatment at 160~240℃ for 6~24h; S4: After the hydrothermal reaction is complete, allow it to cool naturally, wash the reaction product repeatedly with deionized water and anhydrous ethanol, filter, and dry to obtain Bi. 12 TiO 20 powder.

3. The ultrasonic fabrication method according to claim 1 or 2, characterized in that, In S1, the molar ratio of bismuth source to titanium source Bi / Ti is 4:1 or 6:1, wherein the bismuth source is bismuth citrate and the titanium source is titanium dioxide.

4. The ultrasonic fabrication method according to claim 1, characterized in that, In step 2), an ultrasonic cell disruptor is used, with the following settings: ultrasonic frequency 40KHz, ultrasonic power 100W, and ultrasonic treatment for 15 minutes.

5. The ultrasonic fabrication method according to claim 1, characterized in that, The preparation method of GO suspension in step 3) is as follows: take out 1 to 3 ml of monolayer GO dispersion (Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., CAS: 7440-44-0), add 15 ml of deionized water, and use an ultrasonic cell disruptor with the ultrasonic frequency set to 40 kHz and ultrasonic power set to 100 W. After ultrasonic treatment for 15 min, GO suspension is prepared.

6. A graphene oxide / Bi synthesized by ultrasound 12 TiO 20 Composite photocatalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The Graphene Oxide / Bi as described in claim 6 12 TiO 20 Composite photocatalyst, characterized in that: The Graphene Oxide / Bi 12 TiO 20 The composite photocatalyst, as observed under a scanning electron microscope (SEM), consists of graphene oxide (GO) sheets tightly coating a portion of Bi. 12 TiO 20 Nanosheets.

8. The Graphene Oxide / Bi as described in claim 6 12 TiO 20 Composite photocatalyst, characterized in that: It is applied to the catalytic degradation of organic pollutants under visible light.

9. The Graphene Oxide / Bi as described in claim 8 12 TiO 20 Composite photocatalyst, characterized in that, Graphene Oxide / Bi 12 TiO 20 The composite photocatalyst and methyl orange (MO) mixed solution, when irradiated under simulated visible light for 20 minutes, achieved a degradation rate of 98.2% for methyl orange (MO), with a first-order kinetic rate constant k of 0.2167 min. -1 .

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