Non-linear nano hybrid material of titanium carbide quantum dots and vanadium metal organic framework and preparation method thereof
阅读说明：本技术 碳化钛量子点与钒的金属有机框架的非线性纳米杂化材料及其制备方法 (Non-linear nano hybrid material of titanium carbide quantum dots and vanadium metal organic framework and preparation method thereof ) 是由 张弛 单娜滢 伏露露 于 2021-09-22 设计创作，主要内容包括：本发明涉及一种碳化钛量子点与钒的金属有机框架的非线性纳米杂化材料及其制备方法,碳化钛量子点均匀分布在钒的金属有机框架材料表面；采用水热法制备出无机有机纳米杂化功能材料,区别于传统的可溶性金属盐,本发明中金属源来自层状固体材料,对合成的金属有机框架的二维空间成核提供了有效帮助；此金属有机框架二维结构具有较强的吸附性,使碳化钛量子点能够稳定均匀的分布在金属有机框架材料表面,获得结构性良好的复合材料。与现有技术相比,本发明通过碳化钛量子点与金属有机框架之间的相互作用,能明显改善纳米激光测试条件下的反饱和吸收性能,为制备多元化、应用范围更广的非线性及其他功能化材料提供了可能,具有良好的应用前景。(The invention relates to a nonlinear nanometer hybrid material of a metal organic framework of titanium carbide quantum dots and vanadium and a preparation method thereof, wherein the titanium carbide quantum dots are uniformly distributed on the surface of the metal organic framework material of vanadium; the inorganic organic nano hybrid functional material is prepared by a hydrothermal method, and is different from the traditional soluble metal salt, the metal source in the invention is from a layered solid material, and the effective help is provided for the two-dimensional space nucleation of the synthesized metal organic framework; the metal organic framework two-dimensional structure has stronger adsorbability, so that the titanium carbide quantum dots can be stably and uniformly distributed on the surface of the metal organic framework material, and the composite material with good structure is obtained. Compared with the prior art, the method can obviously improve the reverse saturation absorption performance under the nano laser test condition through the interaction between the titanium carbide quantum dots and the metal organic framework, provides possibility for preparing diversified nonlinear and other functional materials with wider application range, and has good application prospect.)
1. The nonlinear nano hybrid material of the metal organic framework of the titanium carbide quantum dots and the vanadium is characterized in that the titanium carbide quantum dots are uniformly distributed on the surface of the metal organic framework material of the vanadium.
2. The nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 1, characterized in that the metal-organic framework material of the vanadium is a vanadium-based two-dimensional metalloporphyrin organic framework material V2C PMOF。
3. The method for preparing the non-linear nano hybrid material of the titanium carbide quantum dot and the metal-organic framework of vanadium according to claim 1 or 2, comprising the following steps:
5,10,15, 20-tetra (4-carboxyphenyl) porphyrin is used as an organic ligand;
etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
4. The method for preparing the nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 3, which is characterized by comprising the following steps:
s1: dissolving methyl p-formylbenzoate in a propionic acid solvent, then slowly dripping pyrrole, and carrying out a condensation reaction by high-temperature reflux to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphine tetramethyl ester;
s2: hydrolyzing the 5,10,15, 20-tetra (4-carboxyphenyl) porphine tetramethyl ester obtained in the step S1 in tetrahydrofuran, methanol and an aqueous solution of sodium hydroxide to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin serving as an organic ligand;
s3: etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
s4: etching titanium aluminum carbide in a hydrogen fluoride solution to obtain titanium carbide, and carrying out high-temperature reaction on the titanium carbide in an N, N-dimethylformamide solution to obtain titanium carbide quantum dots;
s5: and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
5. The method for preparing the non-linear nano hybrid material of the metal organic framework of the titanium carbide quantum dots and the vanadium according to claim 4, wherein in the step S1, the ratio of the dosage of the methyl p-formylbenzoate, the pyrrole and the propionic acid solvent is 0.086 mol: 0.086 mol: 200-1000 mL, the reaction temperature is 130-150 ℃, and the reaction time is 1-24 h; preferably, the ratio of the dosage of the methyl p-formylbenzoate, the pyrrole and the propionic acid solvent is 0.086 mol: 0.086 mol: 500mL, the reaction temperature is 140 ℃, and the reaction time is 12 h.
6. The method for preparing the nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 4, wherein the step S2 comprises any one or more of the following conditions:
(i) the volume ratio of tetrahydrofuran to methanol to the aqueous solution of sodium hydroxide is 0.9-1.1: 0.9-1.1: 0.9-1.1, wherein the concentration of the sodium hydroxide aqueous solution is 2-3 mol/L; preferably, the volume ratio of tetrahydrofuran, methanol and aqueous sodium hydroxide solution is 1: 1: 1, the concentration of the sodium hydroxide aqueous solution is 2.4 mol/L;
(ii) the dosage ratio of the 5,10,15, 20-tetra (4-carboxyphenyl) porphin tetramethyl ester to the tetrahydrofuran is 0.75 g: 20-30 mL; preferably, the ratio of the amount of 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester to tetrahydrofuran is 0.75 g: 25 mL;
(iii) the temperature of the hydrolysis reaction is 70-90 ℃, and the reaction time is 1-24 h; the temperature of the hydrolysis reaction is preferably 80 ℃ and the reaction time is preferably 12 h.
7. The method for preparing the non-linear nano hybrid material of the metal-organic framework of titanium carbide quantum dots and vanadium according to claim 4 or 6, wherein the step S2 further comprises: after the hydrolysis reaction is completed, adding a sufficient amount of 1mol/L dilute hydrochloric acid for acidification until no more precipitate is formed.
8. The method for preparing the nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 4, wherein the step S3 comprises any one or more of the following conditions:
(i) the ratio of the dosage of the vanadium aluminum carbide to the dosage of the hydrogen fluoride solution is 1 g: 10-30 mL, wherein the mass fraction of the hydrogen fluoride solution is 40%; preferably, the ratio of the using amount of the vanadium aluminum carbide to the using amount of the hydrogen fluoride solution is 1 g: 20 mL;
(ii) the etching reaction temperature is 30-40 ℃, and the etching reaction time is 48-144 h; preferably, the etching reaction temperature is 35 ℃, and the etching reaction time is 96 hours;
(iii) the ratio of the amount of tetramethylammonium hydroxide to the amount of vanadium aluminum carbide is 5-15 mL: 1g, and the ratio of the amount of the tetramethyl ammonium hydroxide to the amount of the vanadium aluminum carbide is preferably 10 mL: 1g of a compound;
(iv) the stripping reaction time is 12 to 48 hours, preferably 24 hours.
9. The method for preparing the nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 4, wherein the step S4 comprises any one or more of the following conditions:
(i) the ratio of the dosage of the titanium aluminum carbide to the dosage of the hydrogen fluoride solution is 1 g: 10-30 mL, wherein the mass fraction of the hydrogen fluoride solution is 40%; preferably, the ratio of the dosage of the titanium aluminum carbide to the dosage of the hydrogen fluoride solution is 1 g: 20 mL;
(ii) etching is carried out at normal temperature, and the reaction time is 24-72 h; the preferable reaction time is 48 h;
(iii) carrying out deoxidization operation on the hydrogen fluoride solution before etching;
(iv) carrying out hydrothermal reaction on titanium carbide in an N, N-dimethylformamide solution to prepare titanium carbide quantum dots, wherein the reaction temperature is 140-160 ℃, and the reaction time is 3-12 h; the reaction temperature is preferably 150 ℃ and the reaction time is preferably 6 h.
10. The method for preparing the nonlinear nano hybrid material of the metal-organic framework of the titanium carbide quantum dots and the vanadium according to claim 4, wherein the step S5 comprises any one or more of the following conditions:
(i) the mass ratio of the organic ligand to the metal source to the titanium carbide quantum dots is 130-170 mg: 5-15 mg: 5-15 mg; preferably, the mass ratio of the organic ligand to the metal source to the titanium carbide quantum dots is 150 mg: 10 mg: 10 mg;
(ii) the temperature of the hydrothermal reaction is 160-200 ℃, and the reaction time is 2-6 h; the hydrothermal reaction temperature is preferably 180 ℃ and the reaction time is preferably 4 hours.
Technical Field
The invention belongs to the field of organic-inorganic functional composite materials and strong laser protection materials, and particularly relates to a nanosecond laser-based nonlinear nano hybrid material of titanium carbide quantum dots and a vanadium metal organic framework and a preparation method thereof.
Background
Nonlinear optical materials should be of great importance in optical limiting, optical switching and optical communications. At present, nonlinear optical responses of many two-dimensional materials have been reported (e.g., graphene, transition metal sulfides, topological insulators, metal carbides, and nitrides). Among them, the two-dimensional metal-organic framework is attracting attention as an emerging material in a family of two-dimensional materials. Compared with other materials, the two-dimensional metal-organic framework is formed by coordination of abundant metal materials and different organic ligands, and the chemical diversity of the metal-organic framework is determined. However, two-dimensional metal-organic frameworks are not common as examples of nonlinear optical materials.
In a two-dimensional metal-organic framework, selected organic ligands help polarize the metal-organic framework to enhance the nonlinear optical response. Since ligands can provide additional orbital interactions, metal-mediated intramolecular charge transfer transitions can result, including charge transfer from metal to ligand or from ligand to metal. In the existing systems, two-dimensional metal-organic frameworks based on oxygen-containing organic ligands (benzoate groups) and nitrogen-containing organic ligands (zeolite-imidazolate groups and pyridyl groups) have been explored. Thanks to the 18 pi electron system, porphyrins have a wide range of uses in light collecting and optoelectronic devices. Since the absorption cross section of the excited state is larger than that of the ground state, the porphyrin exhibits a typical reverse saturable absorption. Therefore, porphyrin-based metal-organic frameworks would be promising materials for third-order nonlinear optical responses. The wang subject group showed a multi-level nonlinear optical response in the metalloporphyrin organic framework of the nano-film. The young group demonstrated that the third-order optical nonlinear properties of cobalt-based metalloporphyrin organic frameworks were dependent on morphology. The above work was carried out around metalloporphyrin organic frameworks, but only metallic cobalt was used as the metal source in metalloporphyrin organic frameworks.
Disclosure of Invention
How the electronic structure of the metalloporphyrin organic framework influences the nonlinear optical performance has not been systematically researched so far, which is absolutely essential for developing high-performance metalloporphyrin organic framework nonlinear optical materials.
Vanadium-based metalloporphyrin organic frameworks are emerging materials in many areas, including hydrogen storage, nitrogen dioxide adsorption, supercapacitors, solid electrolytes, and olefin epoxidation. Based on extended conjugated and outgoing electron conductivity, the vanadium-based metalloporphyrin organic frameworks will exhibit good nonlinear optical properties. For the first time, vanadium-based metalloporphyrin organic frameworks were mentioned for nonlinear optical responses. The pores in the vanadium-based metalloporphyrin organic framework can be used as containers. It is expected that a guest such as an optically active molecule is efficiently loaded on the pores of the metal-organic framework. As an accumulation effect of energy transfer/photoinduced electron transfer between a guest and a host, loading functional nanoparticles on the surface of a two-dimensional metalloporphyrin organic framework is a strategy for adjusting or improving a nonlinear optical effect.
Here we used insoluble metal precursor vanadium carbide nanoplates as the metal source for the synthesis of the metal organic framework. The parent characteristics of the product metal organic framework in the reaction can easily inherit the performance of the precursor to form the two-dimensional metalloporphyrin organic framework, which is easier than the Langmuir-Blodgett technology. As a proof of concept, vanadium carbide and (4-carboxyphenyl) porphyrin formed a two-dimensional metalloporphyrin organic framework by a hydrothermal method. Titanium carbide has become a new focus of nonlinear optical research due to its excellent conductive properties. Titanium carbide quantum dots exhibit better solubility in water-soluble solvents and higher atom vacancy densities due to quantum size effects. Under the driving of electrostatic attraction, a heterojunction is synthesized with the vanadium-based organic metal framework.
The present invention has been made in view of the above background.
The invention aims to provide a nonlinear nano hybrid material of titanium carbide quantum dots and a vanadium metal organic framework and a preparation method thereof.
According to the invention, a hydrothermal method is adopted to quickly and efficiently prepare the inorganic-organic nano hybrid functional material, the two-dimensional structure of the metal-organic framework has stronger adsorbability, so that titanium carbide quantum dots can be stably and uniformly distributed on the surface of the metal-organic framework material, and the composite material with good structure is obtained. The method has the advantages that the prepared organic-inorganic covalent nano hybrid material simultaneously combines the characteristics of the metal organic frameworks of titanium carbide and vanadium in the aspects of electronic structure and chemical structure, and enhances the electronic coupling and transfer efficiency between the titanium carbide and vanadium metal organic frameworks, thereby improving the nonlinear optical absorption performance of the material. In addition, the research on the structure of the metal organic framework of the metal vanadium is less, and the invention relates to a nonlinear nano hybrid material of titanium carbide quantum dots and the metal organic framework of vanadium and a preparation method thereof. Under the nanosecond laser test condition of 532nm, the nonlinear optical response of the metal-organic framework hybrid material loaded with the titanium carbide quantum dots is larger than that of the metal-organic framework material not loaded with the titanium carbide quantum dots. Compared with the prior art, the method can obviously improve the reverse saturation absorption performance under the nano laser test condition through the interaction between the titanium carbide quantum dots and the metal organic framework, provides possibility for preparing diversified nonlinear and other functional materials with wider application range, and has good application prospect.
The purpose of the invention can be realized by the following technical scheme:
the invention provides a nonlinear nano hybrid material of titanium carbide quantum dots and a vanadium metal organic framework, which is formed by uniformly distributing titanium carbide quantum dots on the surface of a vanadium metal organic framework material.
Preferably, the vanadium metal-organic framework material is a vanadium-based two-dimensional metalloporphyrin organic framework material V2C PMOF。
The second aspect of the invention provides a preparation method of the nonlinear nano hybrid material of the titanium carbide quantum dots and the vanadium metal organic framework, which comprises the following steps:
5,10,15, 20-tetra (4-carboxyphenyl) porphyrin is used as an organic ligand;
etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
Further preferably, the preparation method comprises the following steps:
s1: dissolving p-formylmethyl benzoate in a propionic acid solvent, then dripping pyrrole slowly, refluxing at high temperature for condensation reaction to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphin tetramethyl ester;
s2: hydrolyzing the 5,10,15, 20-tetra (4-carboxyphenyl) porphine tetramethyl ester obtained in the step S1 in tetrahydrofuran, methanol and an aqueous solution of sodium hydroxide to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin serving as an organic ligand;
s3: etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
s4: etching titanium aluminum carbide in a hydrogen fluoride solution to obtain titanium carbide, and carrying out high-temperature reaction on the titanium carbide in an N, N-dimethylformamide solution to obtain titanium carbide quantum dots;
s5: and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
Preferably, in step S1, the ratio of the amounts of methyl p-formylbenzoate, pyrrole and propionic acid solvent is 0.086 mol: 0.086 mol: 200-1000 mL, the reaction temperature is 130-150 ℃, and the reaction time is 1-24 h; it is further preferred that the ratio of the amounts of methyl p-formylbenzoate, pyrrole and propionic acid solvent is 0.086 mol: 0.086 mol: 500mL, the reaction temperature is 140 ℃, and the reaction time is 12 h.
Preferably, in step S2, the volume ratio of tetrahydrofuran, methanol and aqueous solution of sodium hydroxide is 0.9-1.1: 0.9-1.1: 0.9-1.1, wherein the concentration of the sodium hydroxide aqueous solution is 2-3 mol/L; further preferably, the volume ratio of tetrahydrofuran, methanol and an aqueous solution of sodium hydroxide is 1: 1: 1, the concentration of the sodium hydroxide aqueous solution is 2.4 mol/L.
Preferably, in step S2, the ratio of the amount of 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester to tetrahydrofuran is 0.75 g: 20-30 mL; further preferably, the ratio of the amount of 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester to tetrahydrofuran is 0.75 g: 25 mL.
Preferably, in the step S2, the temperature of the hydrolysis reaction is 70-90 ℃, and the reaction time is 1-24 h; further preferably, the hydrolysis reaction is carried out at a temperature of 80 ℃ for a reaction time of 12 hours.
Preferably, step S2 further includes: after the hydrolysis reaction is completed, adding a sufficient amount of 1mol/L dilute hydrochloric acid for acidification until no more precipitate is formed.
Preferably, in step S3, the ratio of the amount of aluminum vanadium carbide to the amount of hydrogen fluoride solution is 1 g: 10-30 mL, wherein the mass fraction of the hydrogen fluoride solution is 40%; further preferably, the ratio of the dosage of the vanadium aluminum carbide to the dosage of the hydrogen fluoride solution is 1 g: 20 mL.
Preferably, in the step S3, the etching reaction temperature is 30-40 ℃, and the etching reaction time is 48-144 h; further preferably, the etching reaction temperature is 35 ℃ and the etching reaction time is 96 hours.
Preferably, in step S3, the ratio of the amount of tetramethylammonium hydroxide to the amount of aluminum vanadium carbide (precursor to be subjected to etching reaction) is 5 to 15 mL: 1g, and the ratio of the amount of the tetramethylammonium hydroxide to the amount of the aluminum vanadium carbide is preferably 10 mL: 1g of the total weight of the composition.
Preferably, in step S3, the stripping reaction time is 12-48 h, and preferably 24 h.
Preferably, in step S4, the ratio of the titanium aluminum carbide to the hydrogen fluoride solution is 1 g: 10-30 mL, wherein the mass fraction of the hydrogen fluoride solution is 40%; further preferably, the ratio of the amount of the titanium aluminum carbide to the amount of the hydrogen fluoride solution is 1 g: 20 mL.
Preferably, in the step S4, the etching is carried out at normal temperature for 24-72 h; the reaction time is more preferably 48 hours.
Preferably, in step S4, the hydrogen fluoride solution is subjected to an oxygen removal operation before etching.
Preferably, in step S4, the titanium carbide is hydrothermally reacted in N, N-dimethylformamide solution to obtain titanium carbide quantum dots, wherein the reaction temperature is 140 to 160 ℃, and the reaction time is 3 to 12 hours; further preferably, the reaction temperature is 150 ℃ and the reaction time is 6 hours.
Preferably, in step S5, the mass ratio of the organic ligand, the metal source and the titanium carbide quantum dots is 130-170 mg: 5-15 mg: 5-15 mg; further preferably, the mass ratio of the organic ligand to the metal source to the titanium carbide quantum dots is 150 mg: 10 mg: 10 mg.
Preferably, the temperature of the hydrothermal reaction is 160-200 ℃, and the reaction time is 2-6 h. Further preferably, the hydrothermal reaction is carried out at 180 ℃ for 4 hours.
The nonlinear nano hybrid material has stronger linear absorption under Q band and S band, and is derived from organic monomers of organic metal framework. Under the irradiation of nanosecond laser at 532nm, the interaction between the titanium carbide quantum dots and the organic metal framework of vanadium allows stronger nonlinear absorption between the composite materials.
In the nonlinear nano hybrid material, titanium carbide quantum dots are uniformly dispersed on the surface of a metal organic framework, and the three-order nonlinear coefficient of the organic-inorganic hybrid material is enhanced by the enhanced electronic coupling and transmission effect between the titanium carbide quantum dots and the metal organic framework.
The metal source is from a layered solid material, and provides effective help for the two-dimensional space nucleation of the synthesized metal organic framework; the metal organic framework two-dimensional structure has stronger adsorbability, so that the titanium carbide quantum dots can be stably and uniformly distributed on the surface of the metal organic framework material, and the composite material with good structure is obtained. Compared with the prior art, the method can obviously improve the reverse saturation absorption performance under the nano laser test condition through the interaction between the titanium carbide quantum dots and the metal organic framework, provides possibility for preparing diversified nonlinear and other functional materials with wider application range, and has good application prospect.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method utilizes the simple operability of the strategy of the interaction of the titanium carbide quantum dots and the metal organic framework of vanadium, the strategy is flexible and variable, and the method can be used in other fields. And the material has synthesis diversity, and can derive a series of compounds.
(2) The metal source of the metal-organic framework of the vanadium prepared by the invention is from vanadium aluminum carbide. The material is etched and stripped to obtain vanadium carbide with small size and nanometer size, and the vanadium carbide helps the two-dimensional space nucleation of the metal organic framework based on the special layered structure of the vanadium carbide.
Drawings
FIG. 1 is a schematic diagram of a preparation route of a non-linear nano hybrid material of a metal organic framework of titanium carbide quantum dots and vanadium prepared by the invention.
FIG. 2 shows vanadium aluminum carbide (Ti)3AlC2) And vanadium carbide (Ti) prepared by the invention3C2) Vanadium carbide quantum dots (Ti)3C2QD), titanium aluminum carbide (V)2AlC), titanium carbide (V)2C) Stripped titanium carbide (d-V)2C) And non-linear nano hybrid material (Ti) of titanium carbide quantum dots and metal organic framework of vanadium3C2 QD/V2C PMOF) and metal-organic framework reference material (V) of vanadium thereof2C PMOF) X-ray diffraction pattern.
FIG. 3 shows the nano-hybrid material Ti prepared by the present invention3C2 QD/V2Cmpof and reference material V thereof2C PMOF and Ti3C2Infrared spectra of QDs.
FIG. 4 shows the nano-hybrid material Ti prepared by the present invention3C2 QD/V2Cmpof and reference material V thereof2C PMOF and Ti3C2Thermogravimetric analysis profile of QDs.
FIG. 5 shows the nano-hybrid material Ti prepared by the present invention3C2 QD/V2Cmpof and reference material V thereof2C PMOF and Ti3C2Ultraviolet spectrum of QDs and Tauc's plot of their preparation.
FIG. 6 shows a reference material Ti prepared by the present invention3C2Transmission electron microscopy spectra of QDs and their particle size distribution plots.
FIG. 7 is a photograph of a film prepared by the present inventionNano hybrid material Ti3C2 QD/V2Scanning electron microscopy of C PMOF.
FIG. 8 shows the nanometer hybrid material Ti prepared by the present invention3C2 QD/V2Cmpof and reference material V thereof2The nonlinear optical absorption spectrum of C PMOF under 532nm, 12ns laser comprises the transmittance of 79% and 34%, respectively.
Detailed Description
The non-linear nanometer hybrid material of the metal organic framework of the titanium carbide quantum dots and the vanadium is formed by uniformly distributing the titanium carbide quantum dots on the surface of the metal organic framework material of the vanadium.
In the invention, the preferable vanadium metal organic framework material is a vanadium-based two-dimensional metalloporphyrin organic framework material V2C PMOF。
The preparation method of the nonlinear nano hybrid material of the titanium carbide quantum dots and the vanadium metal organic framework comprises the following steps:
5,10,15, 20-tetra (4-carboxyphenyl) porphyrin is used as an organic ligand;
etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
More specifically, the preparation method preferably comprises the steps of:
s1: dissolving p-formylmethyl benzoate in a propionic acid solvent, then dripping pyrrole slowly, refluxing at high temperature for condensation reaction to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphin tetramethyl ester;
s2: hydrolyzing the 5,10,15, 20-tetra (4-carboxyphenyl) porphine tetramethyl ester obtained in the step S1 in tetrahydrofuran, methanol and an aqueous solution of sodium hydroxide to obtain 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin serving as an organic ligand;
s3: etching vanadium aluminum carbide in a hydrogen fluoride solution to obtain vanadium carbide, and then stripping in tetramethylammonium hydroxide to obtain vanadium carbide nanosheets as a metal source;
s4: etching titanium aluminum carbide in a hydrogen fluoride solution to obtain titanium carbide, and carrying out high-temperature reaction on the titanium carbide in an N, N-dimethylformamide solution to obtain titanium carbide quantum dots;
s5: and uniformly mixing the titanium carbide quantum dots with the organic ligand and the metal source, and carrying out high-temperature hydrothermal reaction to obtain the nonlinear nano hybrid material of the titanium carbide quantum dots and the metal organic framework of vanadium.
In step S1, the ratio of the amounts of methyl p-formylbenzoate, pyrrole and propionic acid solvent is preferably 0.086 mol: 0.086 mol: 200-1000 mL, the reaction temperature is 130-150 ℃, and the reaction time is 1-24 h; the ratio of the amounts of methyl p-formylbenzoate, pyrrole and propionic acid solvent used is preferably 0.086 mol: 0.086 mol: 500mL, the reaction temperature is 140 ℃, and the reaction time is 12 h.
In step S2, the volume ratio of tetrahydrofuran, methanol, and the aqueous solution of sodium hydroxide is preferably 0.9 to 1.1: 0.9-1.1: 0.9-1.1, the concentration of the sodium hydroxide aqueous solution is preferably 2-3 mol/L; further preferably, the volume ratio of tetrahydrofuran, methanol and an aqueous solution of sodium hydroxide is 1: 1: 1, the concentration of the aqueous sodium hydroxide solution is preferably 2.4 mol/L. The ratio of the amount of 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester to tetrahydrofuran is preferably 0.75 g: 20-30 mL; further preferably, the ratio of the amount of 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester to tetrahydrofuran is 0.75 g: 25 mL. The temperature of the hydrolysis reaction is preferably 70-90 ℃, and the reaction time is preferably 1-24 h; further preferably, the hydrolysis reaction is carried out at a temperature of 80 ℃ for a reaction time of 12 hours. Step S2 preferably further includes: after the hydrolysis reaction is completed, adding a sufficient amount of 1mol/L dilute hydrochloric acid for acidification until no more precipitate is formed.
In step S3, the ratio of the amount of aluminum vanadium carbide to the amount of hydrogen fluoride solution is preferably 1 g: 10-30 mL, and the mass fraction of the hydrogen fluoride solution is preferably 40%; further preferably, the ratio of the dosage of the vanadium aluminum carbide to the dosage of the hydrogen fluoride solution is 1 g: 20 mL. The etching reaction temperature is preferably 30-40 ℃, and the etching reaction time is preferably 48-144 h; further preferably, the etching reaction temperature is 35 ℃ and the etching reaction time is 96 hours. The ratio of the amount of tetramethylammonium hydroxide to the amount of vanadium aluminum carbide (precursor to be subjected to etching reaction) is preferably 5 to 15 mL: 1g, and the ratio of the amount of the tetramethylammonium hydroxide to the amount of the aluminum vanadium carbide is preferably 10 mL: 1g of the total weight of the composition. The stripping reaction time is preferably 12-48 h, and more preferably 24 h.
In step S4, the ratio of the amount of titanium aluminum carbide to the amount of hydrogen fluoride solution is preferably 1 g: 10-30 mL, and the mass fraction of the hydrogen fluoride solution is preferably 40%; further preferably, the ratio of the amount of the titanium aluminum carbide to the amount of the hydrogen fluoride solution is 1 g: 20 mL. The etching is preferably carried out at normal temperature, and the reaction time is preferably 24-72 h; the reaction time is more preferably 48 hours. The hydrogen fluoride solution is preferably subjected to an oxygen removal operation prior to etching. Preferably, carrying out hydrothermal reaction on titanium carbide in an N, N-dimethylformamide solution to obtain titanium carbide quantum dots, wherein the reaction temperature is preferably 140-160 ℃, and the reaction time is preferably 3-12 h; further preferably, the reaction temperature is 150 ℃ and the reaction time is 6 hours.
In step S5, the mass ratio of the organic ligand, the metal source, and the titanium carbide quantum dots is preferably 130 to 170 mg: 5-15 mg: 5-15 mg; further preferably, the mass ratio of the organic ligand to the metal source to the titanium carbide quantum dots is 150 mg: 10 mg: 10 mg. The temperature of the hydrothermal reaction is preferably 160-200 ℃, and the reaction time is preferably 2-6 h. Further preferably, the hydrothermal reaction is carried out at 180 ℃ for 4 hours.
The present invention will be described or further illustrated below with reference to specific examples, which are intended to provide a better understanding of the technical spirit of the present invention and are not intended to limit the scope of the present invention.
Example 1
Preparation of non-linear nano hybrid materials of titanium carbide quantum dots and vanadium metal organic framework (see the flow chart in fig. 1):
methyl p-formylbenzoate (14.41g, 0.086mol) was dissolved in 250mL of propionic acid solvent, then pyrrole (6.09mL, 0.086mol) was slowly added dropwise to the reagent, and the mixture was refluxed at high temperature for 12 hours. Cooling to the chamberAfter warming, the precipitate was collected by suction filtration and washed with methanol solution, ethyl acetate and tetrahydrofuran, respectively. After drying, a purple solid 5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester (4.2g, 23% yield) was obtained. Hydrogen nuclear magnetic resonance spectroscopy (400MHz, CDCl)3):8.80(s,8H),8.43(dt,8H,J＝8Hz),8.28(dt,8H,J＝8Hz),4.14(s,2H),4.09(s,10H),-2.83(s,2H)。
5,10,15, 20-tetrakis (4-carboxyphenyl) porphine tetramethyl ester (0.75g) was dissolved in a mixed solution of 25mL tetrahydrofuran and 25mL methanol, and an aqueous solution (25mL) of sodium hydroxide (2.40g,60.00mmol) was slowly added dropwise under reflux for 12 hours. After the reaction was complete, the solvent was spun dry and the remaining solids were dissolved in water and heated until all solids were dissolved. Then, 1mol/L dilute hydrochloric acid solution is added dropwise for acidification until no more precipitate is generated. Filtration by suction, washing with water, and drying gave 5,10,15, 20-tetrakis (4-carboxyphenyl) porphyrin (0.66g, 96% yield) as a solid. NMR spectra (400MHz, DMSO-d6) 8.86(s,8H),8.38(d,8H),8.34(d,8H), -2.94(s, 2H).
Deoxygenation was performed on 20mL of hydrogen fluoride solution (40%), nitrogen was bubbled for 20min, and then 1g of aluminum vanadium carbide was added, the etching reaction temperature was 35 ℃ and the etching reaction time was 96 h. And after the reaction is finished, adding deionized water for washing, centrifuging at 3000rpm to obtain solid powder until the pH value of the supernatant is more than 6, and drying and collecting solid vanadium carbide. And stripping the etched vanadium carbide in 10mL of tetramethylammonium hydroxide, reacting at normal temperature for 24h, and centrifugally collecting the stripped vanadium carbide nanosheets.
20mL of a hydrogen fluoride solution (40%) was deoxygenated, nitrogen was bubbled for 20min, and then 1g of titanium aluminum carbide was added, and the reaction time was 48h at room temperature. And after the reaction is finished, adding deionized water and ethanol for washing, centrifuging at 9000rpm to obtain solid powder until the pH value of the supernatant is more than 6, and drying to collect the solid titanium carbide. The titanium carbide obtained by etching is subjected to ultrasonic treatment for 0.5h in 80mL of N, N-dimethylformamide solution, uniformly dispersed, and transferred to a 100mL polytetrafluoroethylene autoclave for hydrothermal reaction to obtain titanium carbide quantum dots with uniform particle size and good dispersion (FIG. 6a of a transmission electron microscope). The diameter of the titanium carbide quantum dot was about 3.73nm (particle size distribution diagram 6b) in a statistical chart of a plurality of particles. The reaction temperature is 150 ℃, and the reaction time is 6 h. After the reaction is finished, the titanium carbide quantum dots are collected by a filter membrane with the diameter of 0.22 mu m.
And (3) carrying out ultrasonic treatment on 10mg of the stripped vanadium carbide nanosheet and 10mg of the titanium carbide quantum dot in an N, N-dimethylformamide solution for 0.5h, then adding 150mg of 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin, and carrying out ultrasonic treatment on the mixed solution for 10 min. After the mixed solution is uniformly dispersed, the mixed solution is transferred to a 50mL high-pressure polytetrafluoroethylene kettle to carry out hydrothermal reaction to prepare the composite material, wherein the reaction temperature is 150 ℃, and the reaction time is 6 hours. And after the reaction is finished, filtering and recovering to obtain the metal organic framework nano composite material of the titanium carbide quantum dots and the vanadium. The titanium carbide quantum dots can be uniformly dispersed on the surface of the metal organic framework, and the loading density of the titanium carbide quantum dots is determined by the added titanium carbide quantum dots. In the material, the metal content of the material can be obtained by X-ray photoelectron spectroscopy, the element proportion of Ti is 4.00%, and the element proportion of V is 0.29%.
FIG. 1 also shows the synthetic route for the metal-organic framework reference material of vanadium. The metal organic framework of the vanadium is prepared by high-temperature hydrothermal reaction of small-size nanosheet vanadium carbide and 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin. And (3) carrying out ultrasonic treatment on 10mg of the stripped vanadium carbide nanosheet in an N, N-dimethylformamide solution for 0.5h, then adding 150mg of 5,10,15, 20-tetra (4-carboxyphenyl) porphyrin, and carrying out ultrasonic treatment on the mixed solution for 10 min. After the mixed solution is uniformly dispersed, the mixed solution is transferred to a 50mL high-pressure polytetrafluoroethylene kettle to carry out hydrothermal reaction to prepare the composite material, wherein the reaction temperature is 150 ℃, and the reaction time is 6 hours. And after the reaction is finished, filtering and recovering to obtain the vanadium metal organic framework nano composite material.
FIG. 2(a) can prove that vanadium aluminum carbide is etched in a hydrogen fluoride solution and stripped in tetramethylammonium hydroxide through an X-ray diffractometer to prepare vanadium carbide with small-size nanosheets. After the vanadium aluminum carbide is etched in the hydrogen fluoride solution, a new peak appears at 9.172 degrees in an X-ray diffraction pattern, and corresponds to a (0002) crystal face of the vanadium carbide. The interlayer spacing of this crystal plane is approximately 1.21nm, which, compared to the interlayer spacing of about 0.65nm for the (0002) crystal plane of aluminum vanadium carbide, can prove successful removal of the aluminum layer from the parent material. On the other hand, after the exfoliation reaction in tetramethylammonium hydroxide, the diffraction angle of the (0002) crystal plane of vanadium carbide was shifted to a small angle, indicating that the interlayer distance was large.
The peak at 39 ° for the aluminum vanadium carbide in fig. 2(a) almost completely disappeared, indicating that the aluminum layer etching of the raw material was successful. The (0002) crystal face of the titanium carbide obtained by etching is slightly shifted to 6.34 degrees from 6.40 degrees compared with the (0002) crystal face of the titanium carbide quantum dot prepared by hydrothermal reaction, and the interlayer spacing is from 6 to 34 degreesIs changed intoAlthough this peak position does not change significantly, the peak pattern becomes much sharper.
The results of the vanadium carbide-derived vanadium metal-organic framework material of fig. 2(b) are very consistent compared to the results of the vanadium-based metal-organic framework simulation. And the X-ray diffraction patterns of the titanium carbide quantum dots and the vanadium metal organic framework show characteristic peaks of the titanium carbide quantum dots and the vanadium metal organic framework, and show the interaction and uniform dispersion between the titanium carbide quantum dots and the vanadium metal organic framework.
FIG. 3 shows the nano-hybrid material Ti prepared by the present invention3C2 QD/V2Cmpof and reference material V thereof2C PMOF and Ti3C2Infrared spectra of QDs. Wavelength is 1461cm-1(yellow dot-dash line) is a bending vibration about C-O, including titanium carbide quantum dots, vanadium-based metal-organic frameworks, and metal-organic frameworks of titanium carbide quantum dots and vanadium. But in Ti3C2 QDs/V2The vibration intensity of the C PMOF material is obviously stronger than that of V2C PMOF, mainly due to the addition of Ti3C2A QD component. In addition, the stretching vibration and the in-plane vibration peak of N-H also appear in the map, which indicates that the metal doping does not occur at the central position of the porphyrin ring. At V2The C PMOF, N-H stretching vibration and the in-plane vibration peak are respectively positioned at 3311cm-1,964cm-1. At Ti3C2 QD/V2C PMOF，The N-H stretching vibration and the in-plane vibration peak are respectively positioned at 3316cm-1,963cm-1。V2C-H bending vibration of the C PMOF material occurs at 1382cm-1And Ti3C2 QD/V2C-H bending vibration in C PMOF occurs at 1398cm-1。
The thermogravimetric analysis of fig. 4 was used to characterize the thermal stability of the material. The first successive phase observed at 50-340 ℃ is due to Ti3C211.1% of the molecules (water and traces of hydrogen fluoride) are lost in the QDs. Oxidation of the hydroxyl groups then occurred with a weight loss of 9.5%. At V2In C PMOF, a loss of 19.5% of N, N-dimethylformamide was first observed. Decomposition of the organic component 5,10,15, 20-tetrakis (4-carboxyphenyl) porphyrin and the framework then occurred at 350 ℃ with a sudden weight loss of 28.2%. Heterostructure Ti3C2 QD/V2The above changes occur in cpmanf.
In the UV-visible spectrum in FIG. 5(a), Ti3C2The predominant absorption of QDs is in the ultraviolet (below 400 nm). Porphyrins as organic linkages show strong Soret and weak Q bands, four of which are observed at lower binding energies due to pi-pi + transitions in the free base porphyrin. This is at V2C PMOF and Ti3C2 QD/V2All can be observed in C PMOF. Subsequently, in FIG. 5(b), Ti3C2QD and Ti3C2 QD/V2The band gap Tauc equation for cpmof was calculated to be 4.05 and 4.20 eV. The band gap of the material after recombination is found to be widened. Typically, the absorption edge is close to zero due to the metallic nature of the carbides. Furthermore, due to the unstable nature of titanium carbide quantum dots, the exposed titanium is very mobile, possibly binding with negatively charged fluorine, oxygen or hydroxyl groups as ligands. Due to this functionalization, titanium carbide quantum dots are classified as semiconductors with energy gaps.
FIG. 6 shows a reference material Ti prepared by the present invention3C2Transmission electron microscopy of QDs (fig. 6(a)) and particle size distribution thereof (fig. 6 (b)). Ti passing through 0.22 μm filter3C2QD, found to be uniform in size.
FIG. 7 shows the nano hybrid material prepared by the present inventionMaterial Ti3C2 QD/V2Scanning electron microscopy of C PMOF. Ti3C2QD/V2The surface morphology of the C PMOF is sheet-shaped.
FIG. 8 vs. V2C PMOF and Ti3C2 QD/V2The C PMOF material is used for carrying out a nonlinear test pattern. For comparison of the materials, two different transmission concentrations were configured. V to have a transmittance at 532nm of 33.9%2C PMOF (FIG. 8(C)) and Ti having a transmittance of 34.1%3C2 QD/V2C PMOF (FIG. 8(d)) was compared, and V having a transmittance of 79.1% was used2C PMOF (FIG. 8(a)) and Ti having a transmittance of 79.0%3C2QD/V2C PMOF (FIG. 8(b)) was compared. Ti3C2 QD/V2The C PMOF nanohybrids show stronger nonlinear optical properties and optically limiting performance at 30 muJ, 50 muJ and 70 muJ in FIG. 8. As mentioned earlier, the enhanced nonlinear properties may be guest Ti3C2QD and host V2Cumulative effect of energy transfer between C PMOF. The effective nonlinear absorption coefficient β eff is an important parameter for studying the applicability of a material as an optical limiter, and the degree of nonlinear optical absorption can be measured, as detailed in table 1 below.
TABLE 1
The embodiments described above are intended to facilitate the understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.