Three-dimensional graphene aerogel photo-Fenton catalyst and preparation method and application thereof

Abstract

This invention belongs to the field of photocatalyst materials technology, specifically relating to a three-dimensional graphene aerogel photo-self-propelled Fenton catalyst, its preparation method, and its application. The preparation method includes: mixing a graphene dispersion containing ethylenediamine with a phenolic resin prepolymer containing ferrocene, phenols, and an alkaline catalyst; followed by a one-step hydrothermal reaction, washing, and freeze-drying to obtain the three-dimensional graphene aerogel photo-self-propelled Fenton catalyst. This catalyst can be used to degrade organic pollutants in water under visible light irradiation.

Description

Technical Field

[0001] This invention belongs to the field of photocatalyst materials technology, specifically relating to a three-dimensional graphene aerogel photo-self-Fenton catalyst, its preparation method, and its application. Background Technology

[0002] Photo-induced Fenton technology is an advanced oxidation process that introduces light radiation into the traditional Fenton system, utilizing photogenerated electrons to accelerate Fe oxidation. 3+ / Fe 2+ The process involves cycling and promoting the in-situ decomposition of hydrogen peroxide (H2O2) to generate highly oxidizing hydroxyl radicals (·OH), thereby significantly increasing the degradation rate of organic pollutants, broadening the applicable pH range of the reaction, and reducing the formation of iron sludge byproducts. The core of this technology lies in the design and preparation of a highly efficient and stable photo-self-Fenton catalyst.

[0003] However, current mainstream photocatalyst systems still face several key challenges. First, many catalysts are in nanoparticle form, and their active components (such as iron-based compounds) are prone to agglomeration during use, leading to a reduction in active sites and a decrease in catalytic efficiency. Second, and more prominently, the interfacial bonding between the catalyst's active components and the support is typically weak. Most preparation methods rely on simple physical adsorption or embedding, resulting in a lack of strong chemical interactions between the active components and the support. This makes them prone to detachment and loss from the support surface during long-term operation or fluid erosion, causing not only a decrease in catalytic activity but also potential secondary pollution. Furthermore, powdered catalysts are difficult to separate and recover from the treatment system, limiting their practical engineering applications.

[0004] To improve the stability and recyclability of catalysts, researchers have attempted to use two-dimensional materials with high specific surface area and excellent conductivity (such as graphene) as supports. Graphene can promote electron transport, which is beneficial for the separation of photogenerated charges. However, two-dimensional graphene sheets are prone to irreversible stacking and aggregation during preparation and use, which greatly reduces their effective specific surface area, limits the full exposure of active sites, and also hinders the mass transfer efficiency between reactants and products. More importantly, even with two-dimensional supports, if the problem of strong bonding between the active component and graphene cannot be solved, the long-term stability of the catalyst cannot be guaranteed, and delamination still occurs.

[0005] Therefore, developing a novel catalyst that can stably load active centers onto a support through strong chemical bonding to solve the problem of deactivation, and that can construct a three-dimensional interconnected porous structure to provide abundant exposure sites, promote mass transfer, and enable convenient recovery, has become a key issue that urgently needs to be addressed to promote the practical application of photo-self-Fenton technology. This invention aims to address the above problems by providing a three-dimensional graphene aerogel-based photo-self-Fenton catalyst and its preparation method, which possesses high stability, high activity, and easy recovery characteristics. Summary of the Invention

[0006] To address the problems of active component agglomeration, weak bonding with the support, easy detachment and deactivation, and difficulty in recycling in existing photo-self-Fenton catalysts, this invention aims to provide a three-dimensional graphene aerogel photo-self-Fenton catalyst, its preparation method, and its applications. This catalyst aims to achieve high dispersibility, high stability, and excellent recyclability by constructing a stable chemical bonding interface between the three-dimensional porous conductive support and the active component, while simultaneously improving its visible light utilization efficiency and photogenerated carrier separation capability, thereby achieving efficient and sustained degradation of organic pollutants in water.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: This invention provides a method for preparing a three-dimensional graphene aerogel photo-self-Fenton catalyst, comprising the following steps: Step S1: Preparation of graphene dispersion: Disperse monolayer graphene in water, add ethylenediamine, stir evenly to obtain dispersion A; Step S2: Preparation of ferrocene-containing phenolic resin prepolymer solution: Ferrocene aldehyde compounds, phenolic compounds and alkaline catalyst are mixed in an aqueous solution, stirred to carry out a prepolymerization reaction, and then formaldehyde is added and stirring is continued to obtain prepolymer solution B. Step S3, In-situ Composite and Hydrothermal Molding: The dispersion A and prepolymer B are mixed and subjected to a hydrothermal reaction at 180-250℃ for 12-24 hours to form a three-dimensional graphene network structure. At the same time, the ferrocene-containing phenolic resin is in-situ loaded onto the three-dimensional graphene network structure through coordination bonds and / or hydrogen bonds. After the reaction is completed, the mixture is cooled and washed to obtain a wet gel. Step S4, Drying: The wet gel is soaked in an organic solvent and freeze-dried to obtain the three-dimensional graphene aerogel photo-self-Fenton catalyst.

[0008] Furthermore, in step S1, the sheet diameter of the monolayer graphene is 2-8 μm.

[0009] Furthermore, in step S2, the ferrocene aldehyde compound is selected from at least one of ferrocene formaldehyde or 1,1'-ferrocene diformaldehyde.

[0010] Furthermore, in step S2, the phenolic compound is selected from one or more of resorcinol, phloroglucinol, and hydroquinone.

[0011] Furthermore, in step S2, the alkaline catalyst is selected from at least one of ammonia, ethylenediamine, or triethylamine.

[0012] Furthermore, in step S2, the amount of the ferrocene aldehyde compound added is 1%-8% of the mass of the phenolic compound.

[0013] Furthermore, in step S2, the stirring time for the prepolymerization reaction is 0.5-6 hours.

[0014] The present invention also provides a three-dimensional graphene aerogel photo-self-Fenton catalyst, which is prepared by the aforementioned preparation method.

[0015] The present invention also provides an application of the three-dimensional graphene aerogel photo-self-Fenton catalyst described above, which generates and activates hydrogen peroxide in situ through photo-self-Fenton reaction under visible light irradiation to degrade organic pollutants in water.

[0016] Compared with the prior art, the advantages of this invention are as follows: (1) High stability and easy recyclability: In-situ formation of the three-dimensional graphene network and in-situ loading of the active components were achieved through a one-step hydrothermal method. The active center (phenolic resin containing ferrocene) is tightly bound to the support through coordination bonds and hydrogen bonds, avoiding the problem of shedding during use. The formation of the coordination bonds and / or hydrogen bonds originates from the coordination between iron atoms in ferrocene and oxygen-containing functional groups (such as -COOH, -OH) on the surface of graphene, as well as the hydrogen bond network between the abundant hydroxyl groups in phenolic resin and graphene or its own hydroxyl groups. This multiple and strong chemical interaction is the fundamental reason for the high stability of the catalyst. The obtained catalyst is a macroscopic bulk and can be efficiently recovered and reused through simple scooping or filtration.

[0017] (2) Highly efficient photo-Fenton catalytic performance: Three-dimensional graphene aerogel provides a huge specific surface area and abundant pores, promoting mass transfer between reactants (such as O2) and products. The high conductivity of graphene accelerates the transport of photogenerated electrons. More importantly, the introduction of ferrocene groups not only acts as Fenton active sites to catalyze the decomposition of H2O2, but also regulates the electronic structure of phenolic resin, enhances its visible light absorption and inhibits photogenerated electron-hole recombination, thereby synergistically improving the in-situ generation efficiency of H2O2 and the yield of ·OH.

[0018] (3) Enhanced light utilization and mass transfer: The three-dimensional porous structure of the catalyst can float on the water surface, effectively constructing a gas-liquid-solid three-phase interface, which greatly enhances the transfer efficiency of O2 from the gas phase to the active site of the catalyst, while improving the capture and utilization of incident light.

[0019] (4) The preparation method is simple and efficient: the "one-step" synthesis integrates the carrier construction and active component loading in the same hydrothermal process, which is simple and easy to prepare on a large scale.

[0020] This invention successfully solves the bottlenecks of poor stability and difficulty in recycling of traditional powder catalysts, and provides a new type of catalytic material that is efficient, stable and environmentally friendly for advanced oxidation technologies. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 A flowchart illustrating the preparation method of the three-dimensional graphene aerogel photo-self-Fenton catalyst provided by the present invention; Figure 2 This is a scanning electron microscope image of the surface morphology of the three-dimensional graphene aerogel provided in Embodiment 3 of the present invention; Figure 3 The image shows a scanning electron microscope image of the cross-sectional morphology of the three-dimensional graphene aerogel provided in Embodiment 3 of the present invention. Detailed Implementation

[0022] 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0024] Please see Figure 1As shown, the present invention also provides a method for preparing a three-dimensional graphene aerogel photo-self-Fenton catalyst, characterized by comprising the following steps: Step S1: Preparation of graphene dispersion: Disperse monolayer graphene in water, add ethylenediamine, stir evenly to obtain dispersion A; Step S2: Preparation of ferrocene-containing phenolic resin prepolymer solution: Ferrocene aldehyde compounds, phenolic compounds and alkaline catalyst are mixed in an aqueous solution, stirred to carry out a prepolymerization reaction, and then formaldehyde is added and stirring is continued to obtain prepolymer solution B. Step S3, In-situ Composite and Hydrothermal Molding: The dispersion A and prepolymer B are mixed and subjected to a hydrothermal reaction at 180-250℃ for 12-24 hours to form a three-dimensional graphene network structure. At the same time, the ferrocene-containing phenolic resin is in-situ loaded onto the three-dimensional graphene network structure through coordination bonds and / or hydrogen bonds. After the reaction is completed, the mixture is cooled and washed to obtain a wet gel. Step S4, Drying: The wet gel is soaked in an organic solvent and freeze-dried to obtain the three-dimensional graphene aerogel photo-self-Fenton catalyst.

[0025] In step S1, the sheet diameter of the monolayer graphene is 2-8 μm.

[0026] In step S2, the ferrocene aldehyde compound is selected from at least one of ferrocene formaldehyde or 1,1'-ferrocene diformaldehyde.

[0027] The phenolic compound is selected from one or more of resorcinol, phloroglucinol, and hydroquinone.

[0028] The alkaline catalyst is selected from at least one of ammonia, ethylenediamine, or triethylamine.

[0029] The amount of the ferrocene aldehyde compound added is 1%-8% of the mass of the phenolic compound.

[0030] The stirring time for the prepolymerization reaction is 0.5-6 hours.

[0031] The present invention also provides a three-dimensional graphene aerogel photo-self-Fenton catalyst, which is prepared by the aforementioned preparation method.

[0032] The present invention also provides an application of the three-dimensional graphene aerogel photo-self-Fenton catalyst described above, which generates and activates hydrogen peroxide in situ through photo-self-Fenton reaction under visible light irradiation to degrade organic pollutants in water.

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, specific embodiments of this invention will be described in detail below. It should be noted that the following embodiments are only for explaining this invention and not for limiting it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] In the following examples and comparative examples, the diameter of the monolayer graphene sheets used was approximately 5 μm, and all reagents used were commercially available analytical grade.

[0035] Example 1 (Comparative Example) In this embodiment, a powdered ferrocene phenolic resin photo-self-Fenton catalyst without a graphene support was prepared as a comparative example.

[0036] 0.0174 g of 1,1'-ferrocene dicarboxaldehyde and 0.4012 g of resorcinol were weighed into 20 mL of deionized water, and 1.0 mL of ammonia (25-28%) was added. The mixture was magnetically stirred at room temperature for 2 hours for prepolymerization. Then, 0.56 mL of formaldehyde solution (37%) was added, and stirring continued for 2 hours. The mixture was transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and placed in an oven at 250 °C for 12 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting solid product was repeatedly washed with deionized water until neutral, and then vacuum dried at 80 °C for 12 hours. After grinding, a reddish-brown powdered catalyst was obtained.

[0037] Example 2 This embodiment prepares a catalyst supported on a three-dimensional graphene aerogel.

[0038] Preparation of dispersion A: Weigh 10 mg of monolayer graphene and disperse it in 10 mL of deionized water. Add 0.10 mL of ethylenediamine and stir magnetically for 20 minutes at room temperature to obtain a uniformly dispersed dispersion A.

[0039] Preparation of prepolymer solution B: Weigh 0.0174 g of ferrocene formaldehyde and 0.4012 g of resorcinol into 20 mL of deionized water, add 1.0 mL of ammonia water, and stir at room temperature for 2 hours; then add 0.56 mL of formaldehyde and continue stirring for 2 hours to obtain prepolymer solution B.

[0040] Dispersion A and prepolymer B were mixed and stirred for 10 minutes, then the mixture was transferred to a 50 mL reactor. The reaction was carried out at 250 °C for 12 hours. After cooling, the black blocky hydrogel was removed and washed three times with deionized water. The sample was then immersed in anhydrous ethanol for 24 hours to displace water and remove small molecule impurities. Finally, the sample was freeze-dried for 24 hours to obtain a lightweight, black three-dimensional graphene aerogel photo-self-Fenton catalyst.

[0041] Example 3 The difference between this embodiment and Example 2 is that the ferrocene aldehyde compound in prepolymer solution B is replaced with 0.0170 g of 1,1'-ferrocenediformaldehyde, while the remaining steps and parameters are exactly the same as in Example 2.

[0042] Example 4 The difference between this embodiment and Example 3 is that the phenolic compound in prepolymer solution B is replaced with 0.40g hydroquinone, while the remaining steps and parameters are exactly the same as in Example 3.

[0043] Example 5 The difference between this embodiment and Example 3 is that the phenolic compound in solution B is replaced with 0.40g of phloroglucinol, while the remaining steps and parameters are exactly the same as in Example 3.

[0044] Example 6 The difference between this embodiment and Example 3 is that the phenolic compound in prepolymer solution B is a mixture of 0.35g resorcinol and 0.05g phenol, while the remaining steps and parameters are exactly the same as in Example 3.

[0045] Example 7 The difference between this embodiment and Example 3 is that the alkaline catalyst used in prepolymer solution B is replaced with 1.0 mL of ethylenediamine, while the remaining steps and parameters are exactly the same as in Example 3.

[0046] Example 8 The difference between this embodiment and Example 3 is that the alkaline catalyst used in prepolymer solution B is replaced with 0.6 mL of 1 mol / L oxalic acid solution, while the remaining steps and parameters are exactly the same as in Example 3.

[0047] Performance testing To evaluate the photo-self-Fenton catalytic performance of the catalysts prepared in Examples 1-8, their in-situ hydrogen peroxide (H2O2) generation capacity and pollutant degradation efficiency were tested.

[0048] Test method: Accurately weigh 50 mg of catalyst (powder in Example 1, aerogel blocks in Examples 2-8, cut into small pieces and weighed), and place it in a quartz beaker containing 50 mL of deionized water for H2O2 production testing; or place it in an aqueous solution containing 50 mL of 20 mg / L chloroquine phosphate (CQ) for degradation testing. Place the beaker on a magnetic stirrer and stir for 30 minutes in the dark to reach adsorption-desorption equilibrium. Then, use a 300 W xenon lamp light source (equipped with a 420 nm filter to simulate visible light), with the light source 10 cm perpendicular to the liquid surface, to begin the photo-reaction.

[0049] Every 20 minutes, 2 mL of the reaction solution was taken using a syringe and filtered through a 0.22 μm aqueous filter membrane. The concentration of H₂O₂ in the filtrate was determined by iodometric titration (absorbance measured at 350 nm wavelength), and the H₂O₂ formation rate (μmol g⁻¹) was calculated. －1 h －1 For the degradation experiment, the absorbance of CQ was measured at a wavelength of 342 nm, and its residual concentration was calculated according to the standard curve to obtain the removal rate. The test results are shown in Table 1.

[0050] Table 1. Photocatalytic performance of catalysts in each example. Results Analysis Combination Figure 2 and Figure 3 (Scanning electron microscope image of the catalyst in Example 3) It can be seen that a graphene aerogel with a rich three-dimensional porous network structure was successfully prepared. The phenolic resin is uniformly distributed in the pores constructed by the graphene sheets, forming a stable composite structure.

[0051] As can be seen from the data in Table 1: The H2O2 yield and degradation rate of Example 1 (pure resin powder) were significantly lower than those of the supported catalyst, demonstrating the importance of the three-dimensional graphene support in providing mass transfer channels and promoting O2 adsorption and electron transport.

[0052] Example 3 exhibits the best overall performance, indicating that the combination of ferrocene dicarboxaldehyde and resorcinol, under the stated preparation conditions, can form an electronic structure that is most favorable for photogenerated charge separation and H2O2 activation reaction.

[0053] Comparing Examples 3, 4, and 5, it can be seen that different phenolic compounds, due to their different conjugated structures and the number of hydroxyl groups, affect the electronic properties of the resin, thus leading to differences in catalytic activity.

[0054] Comparing Examples 3, 7, and 8, it can be seen that the catalysts prepared using alkaline catalysts (ethylenediamine and ammonia) (Examples 3 and 7) generally outperform the samples using the acidic catalyst oxalic acid (Example 8), confirming the key role of the alkaline environment in forming an ideal three-dimensional gel structure and loading interface.

[0055] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0056] Furthermore, it should be noted that the scope of the methods and systems in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0057] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional graphene aerogel photo-self-Fenton catalyst, characterized in that, Includes the following steps: Step S1: Preparation of graphene dispersion: Disperse monolayer graphene in water, add ethylenediamine, stir evenly to obtain dispersion A; the diameter of the monolayer graphene sheet is 2-8 μm; Step S2: Preparation of ferrocene-containing phenolic resin prepolymer solution: 1,1'-ferrocene dicarboxaldehyde, resorcinol, and an alkaline catalyst are mixed in an aqueous solution and stirred for 0.5-6 hours for prepolymerization. Formaldehyde is then added and stirring continues to obtain prepolymer solution B. The amount of 1,1'-ferrocene dicarboxaldehyde added is 1%-8% of the mass of resorcinol. Step S3, In-situ Composite and Hydrothermal Molding: The dispersion A and prepolymer B are mixed and subjected to a hydrothermal reaction at 180-250℃ for 12-24 hours to form a three-dimensional graphene network structure. At the same time, the ferrocene-containing phenolic resin is in-situ loaded onto the three-dimensional graphene network structure through coordination bonds and / or hydrogen bonds. After the reaction is completed, the mixture is cooled and washed to obtain a wet gel. Step S4, Drying: The wet gel is soaked in an organic solvent and freeze-dried to obtain the three-dimensional graphene aerogel photo-self-Fenton catalyst.

2. The preparation method according to claim 1, characterized in that, In step S2, the alkaline catalyst is selected from at least one of ammonia, ethylenediamine, or triethylamine.

3. A three-dimensional graphene aerogel photo-self-Fenton catalyst, characterized in that, It is prepared by the method described in any one of claims 1 or 2.

4. An application of the three-dimensional graphene aerogel photo-self-Fenton catalyst as described in claim 3, which generates and activates hydrogen peroxide in situ through photo-self-Fenton reaction under visible light irradiation to degrade organic pollutants in water.

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