1D / 2D double-heterojunction catalyst, preparation method thereof and application of 1D / 2D double-heterojunction catalyst in photo-assisted high-iodate activated degradation of bisphenol a

Abstract

The present application relates to a kind of 1D / 2D double heterojunction catalyst and its preparation method and its application in photo-assisted high iodate activation degradation bisphenol A.The preparation method of the present application: concentrated hydrochloric acid solution and LiF are mixed, Ti3AlC2 is added, heated reaction, solid-liquid separation is taken solid phase, after washing to neutral, dispersed in ethanol, to obtain MXene ethanol solution;Cerium source aqueous solution is added to MXene ethanol solution and mixed in liquid nitrogen, to obtain mixed solution;Organic ligand, ethanol and pure water are mixed to obtain mixed solution, the mixed solution and mixed solution are mixed and heated, solid-liquid separation is taken precipitate, freeze-drying is obtained powder;The obtained powder is heated and calcined under inert atmosphere, to obtain 1D / 2D double heterojunction catalyst.The present application effectively inhibits photo-generated electron hole recombination by constructing double heterojunction, while realizing ultrafast electron transfer, to enhance oxidation, realizes the high-efficiency photocatalytic activity of "1+1>2".

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a 1D / 2D dual heterojunction catalyst, its preparation method, and its application in the photo-assisted periodate-activated degradation of bisphenol A. Background Technology

[0002] Bisphenol A (BPA) is a plastic additive with a global annual production exceeding 6 million tons. It is widely detected in aquatic environments (at concentrations as high as mg / L), and its endocrine-disrupting effects have been proven to cause reproductive and developmental abnormalities in organisms. Traditional treatment technologies face inherent limitations: the phenolic hydroxyl groups of BPA inhibit microbial activity in biological processes, while adsorbents such as activated carbon only transfer pollutants, posing a risk of secondary release. Traditional advanced oxidation processes (AOPs), such as Fenton or UV / H2O2 systems, primarily rely on hydroxyl radicals (•OH) for oxidation. However, these processes are limited by the extremely short lifetime of •OH (<1 μs) and its susceptibility to quenching by ubiquitous aquatic matrix components (especially carbonates and humic acids). Therefore, there is an urgent need to develop novel AOPs with both high selectivity and resistance to aquatic matrix interference for the advanced treatment of wastewater containing BPA. Conversely, periodate (PI), when activated under appropriate conditions, produces a variety of reactants: firstly, PI itself is a strong oxidant that can directly attack the benzene ring and hydroxyl groups of BPA. Iodine radicals (•IO3) are generated during the reduction of PI, which can subsequently produce •OH. Furthermore, high-valence metal-oxygen complexes formed through the interaction of PI with transition metals (such as iron and manganese) possess stronger oxidizing power. Photo-assisted periodate activation systems (PI-AOPs) selectively generate singlet oxygen (•OH). 1 It is particularly effective in terms of O2. Although PI-based systems have great potential for degrading BPA, their engineering-scale application is still limited by three main factors: (i) insufficient activation efficiency; (ii) inherent disadvantages of photocatalysts (such as instability and recombination); and (iii) performance degradation in complex aqueous matrices.

[0003] Titanium dioxide (TiO2) is a widely used photocatalyst with advantages of stability and low cost. However, its application is hindered by factors such as a wide band gap, limited absorption of sunlight, and rapid charge carrier recombination. Existing designs still have some fundamental limitations. For example, type II heterojunctions sacrifice charge separation, inevitably weakening the oxidation potential and thus affecting their ability to achieve the high oxidation potential required for efficient PI activation. Similarly, type Z heterojunctions (taking the TiO2 / CdS system as an example) rely on interfacial barriers (such as Schottky barriers) to retain high-energy electrons (electrons). - ) and holes (h +However, without conductive bridges, the efficiency of indirect charge transfer via random collisions is very low, creating a kinetic barrier. Therefore, traditional single heterojunctions or type II and Z heterojunctions inherently face difficulties in balancing efficient charge separation and strong redox capabilities. Summary of the Invention

[0004] To address the technical challenges of insufficient catalytic performance, slow reaction kinetics leading to low catalytic efficiency, poor stability resulting in activity degradation during long-term operation, and high cost limiting large-scale application of existing catalysts, this invention provides a 1D / 2D dual heterojunction catalyst, its preparation method, and its application in the photo-assisted periodate-activated degradation of bisphenol A. Based on the structural design of MOFs grown on MXene, this invention proposes a dual heterojunction strategy. The integrated S-type heterojunction / Schottky junction 1D / 2D photocatalyst synergistically suppresses charge recombination while simultaneously achieving ultrafast electron transfer, thereby enhancing oxidation.

[0005] The first objective of this invention is to provide a method for preparing a 1D / 2D dual heterojunction catalyst, comprising the following steps:

[0006] (1) Mix concentrated hydrochloric acid solution and LiF powder evenly, and add Ti3AlC2 to obtain a mixed solution; heat the mixed solution to react; separate the solid phase of the obtained reaction solution into solid and liquid phases, wash the obtained solid phase until neutral, and disperse it in ethanol to obtain MXene ethanol solution;

[0007] (2) Add the cerium source aqueous solution to the MXene ethanol solution, mix and let stand in liquid nitrogen for 10 min to obtain a cerium source-containing mixed solution;

[0008] (3) Mix the organic ligand, ethanol and pure water solution to obtain an organic ligand solution. Mix the cerium source mixed solution obtained in step (2) with the organic ligand solution and then heat the reaction. After the reaction is completed, perform solid-liquid separation to obtain the precipitate. Freeze-dry the obtained precipitate to obtain a powder.

[0009] (4) The obtained powder is heated and calcined in an inert atmosphere to obtain MXene / TiO2 / CeO2 dual heterostructure, namely the 1D / 2D dual heterojunction catalyst.

[0010] In some embodiments of the present invention, in step (1), the concentration of the concentrated hydrochloric acid solution is 8~10M;

[0011] In some embodiments of the present invention, in step (1), the temperature of the heating reaction is 40~50 °C and the reaction time is 48~60 h;

[0012] The concentration of the MXene ethanol solution is 30~60 mg / mL.

[0013] In some embodiments of the present invention, in step (2), the cerium source in the cerium source aqueous solution is selected from cerium nitrate and / or cerium chloride;

[0014] The concentration of the cerium source aqueous solution is 0.08~0.1 mM.

[0015] In some embodiments of the present invention, in step (2), the mass ratio of cerium source to MXene is (14:1)-(15:1).

[0016] In some embodiments of the present invention, in step (3), the reaction is heated to 55~65 °C for 1~1.5 h;

[0017] The mass-to-volume ratio of organic ligand, ethanol, and pure water is (0.4-0.5):10:10 g / mL / mL;

[0018] The organic ligand is selected from 1,3,5-pyromellitic acid and / or terephthalic acid (BDC / H2BDC).

[0019] In some embodiments of the present invention, in step (4), the calcination temperature is 700~850 ℃, the calcination time is 1.5~2 h, and the heating rate is 2~5 ℃ / min.

[0020] In some embodiments of the present invention, in step (4), the inert gas in the inert atmosphere includes nitrogen and / or argon.

[0021] The second objective of this invention is to provide a 1D / 2D dual heterojunction catalyst, prepared by the aforementioned method, wherein a one-dimensional CeO2 rod is grown on the surface of an MXene / TiO2 two-dimensional sheet and bonded by Ti-O-Ce.

[0022] A third objective of this invention is to provide the application of the 1D / 2D dual heterojunction catalyst in the photo-assisted periodate-activated degradation of bisphenol A.

[0023] The technical solution of the present invention has the following advantages compared with the prior art:

[0024] 1) The preparation method of the present invention is simple to operate, low in cost, reproducible and universal.

[0025] 2) This invention prepares a catalyst through a one-step pyrolysis method. Compared with traditional carbon catalysts or metal oxides, this catalyst can form a stable, efficient, atomically dispersed (not easily aggregated) catalyst, avoiding the problems of inefficiency, instability and easy agglomeration of traditional catalysts.

[0026] 3) This invention constructs a double heterojunction and utilizes interface engineering to synergistically optimize the electronic structure, effectively suppressing the recombination of photogenerated electrons and holes, while achieving ultrafast electron transfer, thereby enhancing the oxidation effect and realizing a highly efficient photocatalytic activity of "1+1>2"; that is, through multi-interface synergy, it maximizes charge separation efficiency, minimizes recombination loss, and accurately delivers suitable charge carriers to the corresponding reaction sites. Attached Figure Description

[0027] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0028] Figure 1 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the synthesized material obtained in Example 1 of this invention; wherein, (a) represents the scanning electron microscope (SEM) image and (b) represents the transmission electron microscope (TEM) image.

[0029] Figure 2 This is a spherical aberration electron microscope image from an embodiment of the present invention, showing the atomic-level distribution of the material.

[0030] Figure 3 This is a diagram of the band structure of the present invention.

[0031] Figure 4 These are atomic force microscope (AFM) images and potential analysis diagrams of the synthesized material obtained in Example 1 of this invention; wherein, (a) represents the AFM image; and (b) represents the potential difference diagram.

[0032] Figure 5 This describes the application of the present invention in a photo-assisted activated PI degradation bisphenol A system.

[0033] Figure 6 This is a quenching experiment diagram of the photo-assisted activated PI degradation bisphenol A system according to the present invention.

[0034] Figure 7 This is a graph showing the detection effect of the present invention at different pH ranges.

[0035] Figure 8 This is a diagram showing the experimental results specific to this invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing a 1D / 2D dual heterojunction photocatalyst, as detailed below:

[0039] 1. Add 30 ml of 9 M HCl to the lining of a strong acid-resistant reactor, then add 2.4 g of LiF powder and stir for 5 min;

[0040] 2. Slowly add 1.5 g of Ti3AlC2 to the lining of the reactor from step 1 in a fume hood. After completion, cover the vent. This step takes 10 minutes to obtain a mixed solution. Finally, react the mixed solution in a sand bath at 450 rpm and 45 ℃ for 60 h. Separate the solid and liquid phases, wash the obtained solid phase several times until neutral, centrifuge the dispersion at 3500 rpm for 20 min, collect the upper black solution, and freeze-dry under vacuum overnight. Finally, obtain a few-layer MXene and prepare an MXene ethanol solution with a concentration of 60 mg / mL.

[0041] 3. Add Ce(NO3)3·6H2O (0.09 mM, 45 mL) aqueous solution to MXene ethanol solution, place in liquid nitrogen for 10 min, and obtain a mixed solution;

[0042] 4. Mix 0.42 g of 1,3,5-pyromellitic acid, 10 mL of ethanol and 10 mL of pure water to obtain a mixed solution. Add the mixture obtained in step 3 to the mixed solution and mix and stir evenly. Heat to 60 °C and stir vigorously for 1 h. Separate the solid and liquid to collect the precipitate. Wash the obtained precipitate three times with ultrapure water and anhydrous ethanol respectively. Then collect by centrifugation and freeze-dry under vacuum for 48 h to obtain powder.

[0043] 5. The obtained powder was calcined at 800 °C for 2 h under a nitrogen atmosphere with a heating rate of 2 °C / min, finally yielding an MXene / TiO2 / CeO2 dual heterostructure, i.e., a 1D / 2D photocatalyst. The obtained 1D / 2D dual heterojunction photocatalyst was structurally characterized, and the results are as follows: Figures 1-4 As shown. By Figure 1 and 2 It can be seen that the synthesized S-type heterojunction / Schottky junction 1D / 2D photocatalyst was successfully synthesized, achieving the expected atomic-level dispersion. Figure 3 and 4 It can be seen that the obtained dual heterojunction photocatalyst can be identified as an S-type heterojunction / Schottky junction dual heterojunction, and its name is MXene / TiO2 / CeO2.

[0044] Example 2

[0045] This embodiment provides a method for preparing a 1D / 2D dual heterojunction photocatalyst, as detailed below:

[0046] 1. Add 30 ml of 9 M HCl to the lining of a strong acid-resistant reactor, then add 2.4 g of LiF powder and stir for 5 min;

[0047] 2. Slowly add 1.5 g of Ti3AlC2 to the lining of the reactor from step 1 in a fume hood. After completion, cover the vent. This step takes 10 minutes to obtain a mixed solution. Finally, react the mixed solution in a sand bath at 450 rpm and 45 ℃ for 48 h. Separate the solid and liquid phases, wash the obtained solid phase several times until neutral, centrifuge the dispersion at 3500 rpm for 20 min, collect the upper black solution, and freeze-dry it under vacuum overnight. Finally, obtain a few-layer MXene and prepare an MXene ethanol solution with a concentration of 60 mg / mL.

[0048] 3. Add Ce(NO3)3·6H2O (0.09 mM, 45 mL) aqueous solution to MXene ethanol solution, place in liquid nitrogen for 10 min, and obtain a mixed solution;

[0049] 4. Mix 0.42 g of 1,3,5-pyromellitic acid, 10 mL of ethanol and 10 mL of pure water to obtain a mixed solution. Add the mixture obtained in step 3 to the mixed solution and mix and stir evenly. Heat to 60 °C and stir vigorously for 1 h. Separate the solid and liquid to collect the precipitate. Wash the obtained precipitate three times with ultrapure water and anhydrous ethanol respectively. Then collect by centrifugation and freeze-dry under vacuum for 48 h to obtain powder.

[0050] 5. The obtained powder was calcined at 800 °C for 2 h under a nitrogen atmosphere with a heating rate of 2 °C / min, and finally MXene / TiO2 / CeO2 dual heterostructure, i.e., 1D / 2D photocatalyst, was obtained.

[0051] Example 3

[0052] This embodiment provides a method for preparing a 1D / 2D dual heterojunction photocatalyst, as detailed below:

[0053] 1. Add 30 ml of 9 M HCl to the lining of a strong acid-resistant reactor, then add 2.4 g of LiF powder and stir for 5 min;

[0054] 2. Slowly add 1.5 g of Ti3AlC2 to the lining of the reactor from step 1 in a fume hood. After completion, cover the vent. This step takes 10 minutes to obtain a mixed solution. Finally, react the mixed solution in a sand bath at 450 rpm and 45 ℃ for 60 h. Separate the solid and liquid phases and wash the obtained solid phase several times until neutral. Centrifuge the dispersion at 3500 rpm for 20 min, collect the upper black solution, and freeze-dry it under vacuum overnight. Finally, obtain a few-layer MXene and prepare an MXene ethanol solution with a concentration of 30 mg / mL.

[0055] 3. Add Ce(NO3)3·6H2O (0.09 mM, 45 mL) aqueous solution to MXene ethanol solution, place in liquid nitrogen for 10 min, and obtain a mixed solution;

[0056] 4. A solution containing 0.42 g of 1,3,5-pyromellitic acid, 10 mL of ethanol, and 10 mL of pure water was mixed to obtain a mixed solution. The mixture obtained in step 3 was added to the mixed solution and stirred evenly. The mixture was heated to 60 °C and stirred vigorously for 1 h. The solid and liquid were separated to obtain the precipitate. The precipitate was washed three times with ultrapure water and anhydrous ethanol, respectively. After centrifugation, the precipitate was collected and freeze-dried under vacuum for 48 h to obtain a powder.

[0057] 5. The obtained powder was calcined at 800 °C for 2 h under a nitrogen atmosphere with a heating rate of 2 °C / min, and finally MXene / TiO2 / CeO2 dual heterostructure, i.e., 1D / 2D photocatalyst, was obtained.

[0058] Comparative Example 1

[0059] This comparative example provides an MXene / TiO2, and the specific preparation method is similar to that of Example 1, except that no cerium source is added.

[0060] 1. Add 30 ml of 9 M HCl to the lining of a strong acid-resistant reactor, then add 2.4 g of LiF powder and stir for 5 min;

[0061] 2. Slowly add 1.5 g of Ti3AlC2 to the lining of the reactor from step 1 in a fume hood. After completion, cover the vent. This step takes 10 minutes to obtain a mixed solution. Finally, react the mixed solution in a sand bath at 450 rpm and 45 ℃ for 60 h. Separate the solid and liquid phases, wash the obtained solid phase multiple times until neutral, centrifuge the dispersion at 3500 rpm for 20 min, collect the upper black solution, and freeze-dry it under vacuum overnight. Finally, obtain a few-layer MXene.

[0062] 3. The obtained powder was calcined at 800 °C for 2 h under a nitrogen atmosphere with a heating rate of 2 °C / min to finally obtain the MXene / TiO2 structure.

[0063] Comparative Example 2

[0064] This comparative example provides a CeO2 preparation method as shown below, the difference being that it does not require the preparation of few-layer MXene.

[0065] 1. Mix a Ce(NO3)3·6H2O (0.09 mM, 45 mL) aqueous solution with a solution containing 0.42 g 1,3,5-pyromellitic acid, 10 mL ethanol and 10 mL pure water until homogeneous. Heat to 60 °C and stir vigorously for 1 h. Separate the solid and liquid phases to collect the precipitate. Wash the precipitate three times with ultrapure water and anhydrous ethanol, respectively. Then collect by centrifugation and freeze-dry under vacuum for 48 h to obtain a powder.

[0066] 2. The obtained powder was calcined at 800 °C for 2 h under a nitrogen atmosphere with a heating rate of 2 °C / min to finally obtain CeO2.

[0067] Application examples

[0068] This application example provides a strategy for using 1D / 2D photocatalysts in S-type heterojunctions / Schottky junctions, including the following steps:

[0069] The experiment was conducted under a 35 W cold light LED lamp (wavelength range λ = 400-700 nm). In a typical photocatalysis experiment, the photocatalysts obtained in the examples and comparative examples were mixed with BPA (10 mg / L) to prepare a 50 mL suspension. The pH of the solution was adjusted with 0.1 M H2SO4 or NaOH, with an initial pH of 6.8.

[0070] The experiment was conducted at 25 ℃ and 500 rpm with stirring. Before light exposure, the mixture was stirred in the dark for 120 min to reach adsorption-desorption equilibrium. After equilibrium was established, PI (1.5 mM) was added under light to initiate the reaction. At specific time points (5, 10, 20, and 30 min), 0.9 mL of the sample was taken and filtered through a 0.22 μm filter membrane. At the end of the reaction, 0.1 mL of Na₂S₂O₃ (1 mM) was added.

[0071] BPA was analyzed using a high-performance liquid chromatograph (HPLC, LC-16, Shimadzu). The test conditions were as follows: C18 column, constant temperature 30 °C; total flow rate 1 mL / min; detection wavelength 278 nm; mobile phase was a mixture of 70 vt% methanol and 30 vt% ultrapure water. Experimental results are shown below. Figure 5 .Depend on Figure 5 It can be seen that, compared with MXene / TiO2 and CeO2, the degradation effect of the MXene / TiO2 / CeO2 dual heterojunction is greatly improved, and about 90% of BPA can be degraded within 30 minutes. This also shows that the advantage of the dual heterojunction over the single heterojunction is that it maximizes the charge separation efficiency and minimizes recombination loss through multi-interface synergy, and accurately delivers the appropriate charge carriers to the corresponding reaction sites to achieve the purpose of degrading BPA.

[0072] Mechanism research

[0073] The reaction system of the above application example was investigated through mechanism analysis. Different quenchers were added to the system, and it was found that the system mainly produced... 1 O2、•O2 - and h + / e - This degrades BPA, such as Figure 6 As shown in the figure, different quenching agents added to this system resulted in the following main products: 1 O2、•O2 - and h + / e - Therefore, it can be inferred that the mechanism of BPA degradation mainly involves the generation of... 1 O2、•O2 - and h + / e - Active groups such as these enable the degradation of organic matter.

[0074] Practicality test

[0075] The reaction system of the above application example was subjected to a practical test by adjusting the initial solution to different pH values ​​(3, 5, 7, 9, 11). The experimental results are shown in [Figure number missing]. Figure 7 As shown in the figure, this system has a wide pH range and can effectively degrade BPA.

[0076] Specificity test

[0077] Specificity tests were conducted using the reaction system from the application example. Photo-assisted degradation experiments of periodate were performed by replacing BPA with different pollutants (Rhodamine B, tetracycline hydrochloride, 2,4,6-trichlorophenol, ciprofloxacin). The experimental results are shown in [Figure number missing]. Figure 8 As shown in the figure, this system can effectively and selectively degrade BPA.

[0078] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a 1D / 2D dual heterojunction catalyst, characterized in that, Includes the following steps: (1) Mix concentrated hydrochloric acid solution and LiF powder evenly, and add Ti3AlC2 to obtain a mixed solution; heat the mixed solution to react; separate the solid phase of the obtained reaction solution into solid and liquid phases, wash the obtained solid phase until neutral, and disperse it in ethanol to obtain MXene ethanol solution; (2) Add the cerium source aqueous solution to the MXene ethanol solution, mix and let stand in liquid nitrogen to obtain a cerium source-containing mixed solution; (3) Mix the organic ligand, ethanol and pure water solution to obtain an organic ligand solution. Mix the cerium source mixed solution obtained in step (2) with the organic ligand solution and then heat the reaction. After the reaction is completed, perform solid-liquid separation to obtain the precipitate. Freeze-dry the obtained precipitate to obtain a powder. The organic ligand is selected from 1,3,5-pyromellitic acid and / or terephthalic acid. (4) The obtained powder is heated and calcined under an inert atmosphere to obtain MXene / TiO2 / CeO2 dual heterostructure, namely the 1D / 2D dual heterojunction catalyst; the calcination temperature is 700~850 ℃, the calcination time is 1.5~2 h, and the heating rate is 2~5℃ / min; The 1D / 2D dual heterojunction catalyst is a one-dimensional CeO2 rod grown on the surface of an MXene / TiO2 two-dimensional sheet and bonded by Ti-O-Ce.

2. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the concentrated hydrochloric acid solution is 8~10M.

3. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the heating reaction is 40~50℃ and the reaction time is 48~60 h; The concentration of the MXene ethanol solution is 30~60 mg / mL.

4. The preparation method according to claim 1, characterized in that, In step (2), the cerium source in the cerium source aqueous solution is selected from cerium nitrate and / or cerium chloride; The concentration of the cerium source aqueous solution is 0.08~0.1 mM.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of cerium source to MXene is (14:1) - (15:1).

6. The preparation method according to claim 1, characterized in that, In step (3), the reaction is heated to 55~65 °C for 1~1.5 h; The mass-to-volume ratio of the organic ligand, ethanol, and pure water is (0.4-0.5): 10:10 g / mL / mL.

7. The preparation method according to claim 1, characterized in that, In step (4), the inert gas in the inert atmosphere includes nitrogen and / or argon.

8. A 1D / 2D dual heterojunction catalyst, characterized in that, The MXene / TiO2 two-dimensional sheet surface is prepared by any one of the preparation methods described in claims 1 to 7, and a one-dimensional CeO2 rod is grown on it and bonded by Ti-O-Ce.

9. The application of the 1D / 2D dual heterojunction catalyst described in claim 8 in the photo-assisted periodate-activated degradation of bisphenol A.

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