Polycation liquid confinement nonmetal monatomic loaded two-dimensional material and preparation method thereof

Abstract

The invention discloses a polycation liquid confinement nonmetal monatomic loaded two-dimensional material and a preparation method thereof, and is characterized in that: a positively charged polycation liquid and a two-dimensional material with a negatively charged surface attract each other through electrostatic interaction, and are subjected to vacuum calcination to obtain the polycation liquid confinement nonmetal monatomic loaded two-dimensional material. And non-metal atoms limited by the polycation liquid are in atomic-scale dispersion on the two-dimensional material. Comprising the following steps: anchoring a non-metallic element in a polycation liquid skeleton, then fully mixing the non-metallic element with a two-dimensional material through electrostatic interaction, and carrying out vacuum calcination to obtain the non-metallic monatomic loaded two-dimensional material. According to the invention, non-metallic elements are anchored by innovatively adopting a polycation liquid confinement mode, and by virtue of defect vacancies in a two-dimensional nanosheet structure, the atomic-scale dispersed non-metallic monatomic loaded two-dimensional nano material is obtained. The nonmetal monatomic loaded two-dimensional nano material prepared by the method has a wide application prospect in the fields of catalysis, antibiosis, optics and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material, belonging to the technical field of composite material and functional nano material preparation. Background Art

[0002] Single-atom catalysts have atomically dispersed active sites and have higher atom utilization, catalytic activity, selectivity and stability than traditional catalysts, and have attracted widespread attention in the field of heterogeneous catalysis. Currently, researchers have developed a series of transition metal and noble metal single-atom catalysts and confirmed the high catalytic activity and other properties of single-atom catalysts.

[0003] Ionic liquids can increase the activation energy of single-atom aggregation and provide an "electronic protection layer", thereby effectively stabilizing single atoms. In addition, due to the positive and negative ion effects of ionic liquids, their physicochemical properties can be effectively regulated by changing the types and concentrations of anions and cations, thereby achieving efficient single-atom catalysis. CN 111514930A synthesized a series of ionic liquid-stabilized metal single-atom catalysts by precipitation deposition method, which greatly improved the stability of the reaction and the economy of the process. CN 114318403 B discloses a method for preparing platinum single-atom materials by cyclic voltammetry using alkyl imidazole ionic liquids as electrolytes, and the prepared platinum single-atom-loaded composite electrode material has good hydrogen evolution catalytic activity. Non-metallic single-atom catalysts have the characteristics of good biocompatibility, biosafety, high economy, excellent light responsiveness, etc. Compared with transition metal and noble metal single-atom catalysts, non-metallic single-atom catalysts have the advantages of low toxicity, low cost, good biocompatibility, etc., and have a wider application prospect in the field of catalysis. However, there are few reports on the research on ionic liquid stabilization of non-metallic single atoms.

[0004] Polyionic liquids (PILs) are polymers obtained from ionic liquids through a certain polymerization method. They have the characteristics of both polymers and ionic liquids, and have extensive designability, mechanical stability, safety, and molecular self-assembly performance, and are easier to recycle. At present, most two-dimensional materials such as graphene, black phosphorus, and MXene have negative charges on their surfaces, while polycationic liquids have positive charges, and electrostatic attraction is easily generated between the two, which can not only significantly reduce the aggregation of single atoms in the skeleton of two-dimensional nanomaterials, but also has important significance for the preparation of high-performance single-atom-loaded two-dimensional nanomaterials. The present invention uses the electrostatic interaction between positively charged polycationic liquids and two-dimensional materials with negative charges on the surface to introduce non-metallic single atoms in polycations into defects of two-dimensional nanomaterials. The research has extremely high originality and can provide novel design ideas for the development of efficient non-metallic single-atom-loaded two-dimensional nanomaterials. Summary of the invention

[0005] The purpose of the present invention is to provide a polycationic liquid confined non-metallic single atom loaded two-dimensional material and a preparation method thereof, the specific steps comprising:

[0006] 1. Synthesis of polycationic liquid

[0007] (1) Synthesis of ionic liquids: 1-vinyl imidazole is fully dissolved in acetone, reactant X-R1 is added dropwise to the solution, magnetically stirred for 24 hours, the product is filtered and washed, and vacuum dried to obtain imidazole ionic liquids. The reaction formula is as follows:

[0008]

[0009] Among them, X — Br — ,I — , Cl — 、BF4 — PF6 — NTf2 — TFSI — 、H2PO4 — 、NO3 — 、C7H7SO3 — 、CH3SO3 — or C2H5COO — etc. leaving group.

[0010] R1 is N + R4, CN, NO2, SO3H, F, Cl, Br, I, HC≡C—, CH3O—, C6H5, CH2=CH

[0011] —, COO— and other electron-withdrawing groups.

[0012] (2) Synthesis of polycationic liquid: The imidazole ionic liquid obtained in step (1) is fully dissolved in dimethyl sulfoxide, an initiator is added, and the mixed solution is reacted at 80° C. for 24 h. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, and the precipitate is collected by filtration, washing, and vacuum drying to obtain a polyimidazole ionic liquid. The reaction formula is as follows:

[0013]

[0014] Wherein, the initiator is potassium persulfate, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, N,N-dimethylaniline or ammonium persulfate.

[0015] X — Br — ,I — , Cl — 、BF4 — PF6— NTf2 — TFSI — 、H2PO4 — 、NO3 — 、C7H7SO3 — 、CH3SO3 — or C2H5COO — etc. leaving group.

[0016] R1N + R4, CN, NO2, SO3H, F, Cl, Br, I, HC≡C—, CH3O—, C6H5, CH2=CH—,

[0017] COO—equal electron-withdrawing group.

[0018] 2. Synthesis of polycationic liquids containing non-metallic elements

[0019] The polycationic liquid containing non-metallic elements is synthesized by anion replacement reaction: the polycationic liquid and the non-metallic salt are dissolved in the carrier solution respectively, and then the non-metallic salt solution is slowly added dropwise to the polycationic liquid solution, and the stirring is continued for 10-60 minutes. After the reaction is completed, the precipitate is filtered and collected, washed and dried in vacuum at 40-80°C to obtain a polycationic liquid doped with non-metallic elements. The reaction formula is as follows:

[0020]

[0021] Among them, X — Br — ,I — , Cl — 、BF4 — PF6 — NTf2 — TFSI — 、H2PO4 — 、NO3 — 、C7H7SO3 — 、CH3SO3 — or C2H5COO — etc. leaving group.

[0022] R1 and R2 are N + R4, CN, NO2, SO3H, F, Cl, Br, I, HC≡C—, CH3O—, C6H5, CH2=CH

[0023] —, COO— and other electron-withdrawing groups.

[0024] M + K + 、Na +etc. metal cations.

[0025] Y is one of the non-metallic elements Se, Te, B and Si.

[0026] The carrier solvent is one or two of deionized water, N,N-dimethylformamide, chloroform, acetone, anhydrous ethanol, dioxane, tetrahydrofuran, benzene, toluene, ethyl acetate, dichloromethane and chloroform.

[0027] The concentration ratio of the polyimidazole cationic liquid and the non-metallic salt in the carrier solvent is 0.1-2.

[0028] 3. Preparation of non-metallic single atom-loaded porous carbon nanomaterials

[0029] The polyimidazole cationic liquid containing non-metallic elements and the dispersion of two-dimensional nanomaterials are fully mixed in a certain proportion, vacuum dried at 40-80°C, and calcined at 300-800°C for 1-12h under vacuum conditions to obtain non-metallic single atom-loaded two-dimensional nanomaterials.

[0030] The two-dimensional nanomaterial is one or two of graphene oxide, reduced graphene oxide, graphene, graphyne, MXene, black phosphorus, and borophene, and the dispersant is ethanol or isopropanol with a concentration of 0.1-20wt%.

[0031] The mass ratio of the polyimidazole cationic liquid containing non-metallic elements to the two-dimensional nanomaterial dispersion is 0.05–1.

[0032] In summary, the polycationic liquid confined non-metallic single atom-loaded two-dimensional nanomaterial prepared by the present invention has the following advantages over the prior art:

[0033] 1. The present invention innovatively uses a polycationic liquid confinement method to anchor non-metallic single atoms. The polyimidazole cationic liquid is a green and non-toxic green solvent that can not only stabilize the active ingredients of non-metallic elements and anchor non-metallic atoms, but also increase the activation energy of single-atom aggregation and provide an electronic protection layer, thereby effectively improving the catalytic activity and stability of non-metallic single atoms.

[0034] 2. The present invention innovatively utilizes the electrostatic interaction between the positively charged polycationic liquid and the negatively charged two-dimensional nanomaterial to fully mix the polycationic liquid and the two-dimensional nanomaterial, thereby greatly improving the dispersibility of the polycationic liquid in the two-dimensional nanomaterial and minimizing the agglomeration phenomenon, which is beneficial to the efficient preparation of non-metallic single atoms, fully exposing the active sites and improving the catalytic activity.

[0035] 3. The non-metallic single-atom-loaded two-dimensional nanomaterials prepared in the present invention innovatively use non-metallic single atoms Se, Te, B, and Si as active sites. Compared with transition metal and noble metal single-atom catalysts, non-metallic single atoms have good biocompatibility, biosafety, high economy, excellent photoresponsiveness, etc., which are incomparable to transition metal and noble metal single-atom catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a spherical aberration corrected transmission electron microscope image of the selenium single atom-loaded graphyne nanosheet obtained in Example 1. DETAILED DESCRIPTION

[0037] The preparation of the two-dimensional nanomaterials loaded with polycationic liquid confined non-metallic single atoms of the present invention is further described below through specific examples.

[0038] Example 1

[0039] Synthesis of cationic liquid: 1-vinyl imidazole is fully dissolved in acetone, and the reactant Br-CN is added dropwise to the above solution. The mixture is magnetically stirred for 24 hours. The product is filtered, washed, and vacuum dried to obtain a cationic liquid.

[0040] Synthesis of polycationic liquid: The above cationic liquid is fully dissolved in dimethyl sulfoxide, azobisisobutyronitrile is added as an initiator, and the mixed solution is reacted at 80°C for 24 hours. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, the precipitate is collected by filtration, washing, and vacuum drying to obtain the polycationic liquid.

[0041] Synthesis of selenium-containing polycationic liquid: The above-mentioned polycationic liquid and potassium selenocyanate (1:1) were dissolved in deionized water respectively, and then the solution containing potassium selenocyanate was slowly added dropwise to the polycationic liquid solution, and stirring was continued for 30 minutes. After the reaction was completed, the precipitate was filtered and collected, washed and dried in vacuum at room temperature to obtain a selenium-doped polycationic liquid.

[0042] Preparation of selenium single atom loaded graphyne nanosheets: The above-mentioned selenium-containing polycationic liquid and graphyne ethanol solution (1wt%) are fully mixed in a mass ratio of 1:1, vacuum dried at 80°C, and then calcined and carbonized at 400°C under vacuum conditions for 2h to obtain selenium single atom loaded graphyne nanosheets.

[0043] Figure 1 This is a spherical aberration corrected transmission electron microscope image of the graphyne nanosheet loaded with selenium single atoms obtained in this example. From the image, it can be seen that the Se element is dispersed at the atomic level in the graphyne nanosheet.

[0044] Example 2

[0045] Synthesis of cationic liquid: 1-vinyl imidazole is fully dissolved in acetone, and the reactant Br-CN is added dropwise to the above solution. The mixture is magnetically stirred for 24 hours. The product is filtered, washed, and vacuum dried to obtain a cationic liquid.

[0046] Synthesis of polycationic liquid: The above cationic liquid is fully dissolved in dimethyl sulfoxide, azobisisobutyronitrile is added as an initiator, and the mixed solution is reacted at 80°C for 24 hours. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, the precipitate is collected by filtration, washing, and vacuum drying to obtain the polycationic liquid.

[0047] Synthesis of selenium-containing polycationic liquid: The above-mentioned polycationic liquid and potassium selenocyanate (1:1) were dissolved in deionized water respectively, and then the solution containing potassium selenocyanate was slowly added dropwise to the polycationic liquid solution, and stirring was continued for 30 minutes. After the reaction was completed, the precipitate was filtered and collected, washed and dried in vacuum at room temperature to obtain a selenium-doped polycationic liquid.

[0048] Preparation of graphene oxide nanosheets loaded with single selenium atoms: The above-mentioned polycationic liquid containing selenium element and the isopropanol alcohol solution of graphene oxide (2wt%) are fully mixed in a mass ratio of 1:2, and after vacuum drying at 80°C, they are calcined and carbonized at 500°C under vacuum conditions for 2h to obtain graphene oxide nanosheets loaded with single selenium atoms.

[0049] Example 3

[0050] Synthesis of cationic liquid: 1-vinyl imidazole is fully dissolved in acetone, and the reactant Br-CN is added dropwise to the above solution. The mixture is magnetically stirred for 24 hours. The product is filtered, washed, and vacuum dried to obtain a cationic liquid.

[0051] Synthesis of polycationic liquid: The above cationic liquid is fully dissolved in dimethyl sulfoxide, azobisisobutyronitrile is added as an initiator, and the mixed solution is reacted at 80°C for 24 hours. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, the precipitate is collected by filtration, washing, and vacuum drying to obtain the polycationic liquid.

[0052] Synthesis of tellurium-containing polycationic liquid: The above polycationic liquid and sodium tellurite (1:1) were dissolved in deionized water respectively, and then the sodium tellurite solution was slowly added dropwise to the polycationic liquid solution, and stirring was continued for 30 minutes. After the reaction was completed, the precipitate was filtered and collected, washed and dried in vacuum at room temperature to obtain a tellurium-doped polycationic liquid.

[0053] Preparation of tellurium single atom-loaded graphene oxide nanosheets: The above-mentioned tellurium-containing polycationic liquid and the isopropanol alcohol solution of graphene oxide (2wt%) are fully mixed in a mass ratio of 1:2, and after vacuum drying at 80°C, they are calcined and carbonized at 350°C under vacuum conditions for 2h to obtain tellurium single atom-loaded graphene oxide nanosheets.

[0054] Example 4

[0055] Synthesis of cationic liquid: 1-vinyl imidazole is fully dissolved in acetone, and the reactant Br-CN is added dropwise to the above solution. The mixture is magnetically stirred for 24 hours. The product is filtered, washed, and vacuum dried to obtain a cationic liquid.

[0056] Synthesis of polycationic liquid: The above cationic liquid is fully dissolved in dimethyl sulfoxide, azobisisobutyronitrile is added as an initiator, and the mixed solution is reacted at 80°C for 24 hours. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, the precipitate is collected by filtration, washing, and vacuum drying to obtain the polycationic liquid.

[0057] Synthesis of polycationic liquid containing boron element: The above polycationic liquid and borate (1:1) are dissolved in deionized water respectively, and then the borate solution is slowly added dropwise to the polycationic liquid solution, and stirring is continued for 30 minutes. After the reaction is completed, the precipitate is filtered and collected, washed and dried in vacuum at room temperature to obtain a polycationic liquid doped with boron element.

[0058] Preparation of black phosphorus nanosheets loaded with single boron atoms: The above-mentioned polycationic liquid containing boron element and the isopropanol solution of black phosphorus (2wt%) are fully mixed in a mass ratio of 1:5, and after vacuum drying at 80°C, they are calcined and carbonized at 700°C under vacuum conditions for 3 hours to obtain black phosphorus nanosheets loaded with single boron atoms.

[0059] Example 5

[0060] Synthesis of cationic liquid: 1-vinyl imidazole is fully dissolved in acetone, and the reactant Br-CN is added dropwise to the above solution. The mixture is magnetically stirred for 24 hours. The product is filtered, washed, and vacuum dried to obtain a cationic liquid.

[0061] Synthesis of polycationic liquid: The above cationic liquid is fully dissolved in dimethyl sulfoxide, azobisisobutyronitrile is added as an initiator, and the mixed solution is reacted at 80°C for 24 hours. After the reaction is completed and cooled to room temperature, the reaction solution is added dropwise to an excess of tetrahydrofuran, the precipitate is collected by filtration, washing, and vacuum drying to obtain the polycationic liquid.

[0062] Synthesis of polycationic liquid containing boron element: The above polycationic liquid and borate (1:1) are dissolved in deionized water respectively, and then the borate solution is slowly added dropwise to the polycationic liquid solution, and stirring is continued for 30 minutes. After the reaction is completed, the precipitate is filtered and collected, washed and dried in vacuum at room temperature to obtain a polycationic liquid doped with boron element.

[0063] Preparation of MXene nanosheets loaded with single boron atoms: The above-mentioned boron-containing polycationic liquid was mixed with Ti3CNT x The isopropanol solution (2 wt%) of boron was mixed with the Ti3CNT nanostructured carbon nanotubes in a mass ratio of 1:3, dried at 80 °C in vacuum, and then calcined and carbonized at 300 °C for 2 h under vacuum to obtain boron single atom-loaded Ti3CNT nanostructured carbon nanotubes. x Nanosheets.

Claims

1. A method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material, characterized in that: The following steps are involved: Through the anion replacement reaction between the polyimidazole cationic liquid and the non-metallic salt, the non-metallic atoms are anchored into the polyimidazole cationic liquid skeleton; The polyimidazole cationic liquid containing non-metallic elements and the dispersion of two-dimensional nanomaterials are fully mixed in a certain proportion, vacuum dried at 40-80°C, and calcined at 300-800°C under vacuum conditions for 1 to 12 hours to obtain non-metallic single atom-loaded two-dimensional nanomaterials.

2. The method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material according to claim 1, characterized in that: The polycationic liquid anchors the non-metallic element by using the following anion replacement reaction: Among them, X — Br — ,I — , Cl — 、BF4 — PF6 — NTf2 — TFSI — 、H2PO4 — 、NO3 — 、C7H7SO3 — 、CH3SO3 — or C2H5COO — Leaving group; R1 and R2 are N + R4, CN, NO2, SO3H, F, Cl, Br, I, HC≡C-, CH3O-, C6H5, CH2=CH-, one of the electron-withdrawing groups in COO-; M + K + Or Na + Metal cation; Y is one of the non-metal elements Se, Te, B, and Si.

3. The method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material as claimed in claim 1, characterized in that: The anion replacement reaction adopts the following steps: the polyimidazole cationic liquid and the non-metallic salt are dissolved in the carrier solution respectively, and then the non-metallic salt solution is slowly added dropwise to the polyimidazole cationic liquid solution, and stirring is continued for 10-60 minutes. After the reaction is completed, the precipitate is filtered and collected, and after washing, it is placed in a vacuum dryer at 40-80°C to obtain a polyimidazole cationic liquid doped with a non-metallic element.

4. A method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material as claimed in claim 3, characterized in that: The carrier solvent of the anion replacement reaction is one or two of deionized water, N,N-dimethylformamide, chloroform, acetone, anhydrous ethanol, dioxane, tetrahydrofuran, benzene, toluene, ethyl acetate, dichloromethane and chloroform.

5. The method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material as claimed in claim 1, characterized in that: The concentration ratio of the polyimidazole cationic liquid and the non-metallic salt in the carrier solvent is 0.1-2.

6. The method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material as claimed in claim 1, characterized in that: The two-dimensional nanomaterial is one or two of graphene oxide, reduced graphene oxide, graphene, graphyne, MXene, black phosphorus, and borophene, and the dispersant is ethanol or isopropanol with a concentration of 0.1-20wt%.

7. The method for preparing a polycationic liquid confined non-metallic single atom-loaded two-dimensional material as claimed in claim 1, characterized in that: The mass ratio of the polyimidazole cationic liquid containing non-metallic elements to the two-dimensional nanomaterial dispersion is 0.05-1.

8. A polycationic liquid confined non-metallic single atom loaded two-dimensional material, characterized in that: The invention is prepared by the method according to any one of claims 1 to 7.

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