阅读说明：本技术 一种十二面体结构的Fe掺杂ZnO纳米颗粒 (Fe-doped ZnO nanoparticle with dodecahedron structure ) 是由 曾毅 郑莹莹 乔靓 于 2021-08-26 设计创作，主要内容包括：本发明公开了一种十二面体结构的Fe掺杂ZnO纳米颗粒,通过以下步骤制备而成：(1)将锌源和铁源溶解在去离子水中得到锌铁源液；将2-甲基咪唑溶解到去离子水中,得到2-甲基咪唑溶液；(2)将锌铁源液和2-甲基咪唑溶液混合并通过搅拌进行均质化,然后,室温下避光静置反应,反应结束后将沉淀物离心、洗涤、干燥,得到ZnFe-ZIF前体；(3)将ZnFe-ZIF前体高温退火,冷却,得到十二面体结构的Zn-(1-x)Fe-(x)O纳米颗粒。本发明采用MOF前体简化掺杂步骤,并且材料内部结构容易控制,可以为实心、单壳以及双壳十二面体结构,形貌均匀、分散性和结晶性良好,表面化学活性高,比表面积大。(The invention discloses Fe-doped ZnO nanoparticles with a dodecahedron structure, which are prepared by the following steps: (1) dissolving a zinc source and an iron source in deionized water to obtain zinc-iron source liquid; dissolving 2-methylimidazole in deionized water to obtain a 2-methylimidazole solution; (2) mixing zinc-iron source solution and 2-methylimidazole solution, homogenizing by stirring, then standing at room temperature in a dark place for reaction, and after the reaction is finished, centrifuging, washing and drying a precipitate to obtain a ZnFe-ZIF precursor; (3) annealing the ZnFe-ZIF precursor at high temperature, and cooling to obtain Zn with a dodecahedral structure 1‑x Fe x And (3) O nanoparticles. The invention adopts MOF precursor to simplify the doping step, and the internal structure of the material is easy to control, and the material can be a solid, single-shell or double-shell dodecahedron structure, and has uniform appearance, good dispersibility and crystallinity, high surface chemical activity and large specific surface area.)

1. Zn with dodecahedron structure_1-xFe_xO nanoparticles, characterized by being prepared by the following steps:

(1) dissolving a zinc source and an iron source in deionized water, and uniformly stirring and mixing to obtain a zinc-iron source liquid; meanwhile, dissolving 2-methylimidazole in deionized water, and stirring until the 2-methylimidazole is completely dissolved to obtain a 2-methylimidazole solution;

(2) mixing zinc-iron source solution and 2-methylimidazole solution, homogenizing by stirring, standing at room temperature in a dark place for 12-96 hours, carrying out centrifugal separation after the reaction is finished to obtain precipitate, washing the precipitate with methanol for multiple times, and drying to obtain a ZnFe-ZIF precursor with a solid dodecahedron structure;

(3) annealing ZnFe-ZIF precursor with a solid dodecahedron structure at high temperature of 350-450 ℃ for 1-4 hours, and cooling to obtain Zn with a dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

2. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles are characterized in that ZnFe-ZIF precursor with a solid dodecahedron structure is annealed for 2 hours at the temperature rising rate of 2-20 ℃/min and the temperature rising temperature of 350 ℃ in the air atmosphere, and then cooled to obtain Zn with the solid dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

3. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles are characterized in that ZnFe-ZIF precursor with a solid dodecahedron structure is heated to 400 ℃ at the speed of 2 ℃/min in air atmosphere for annealing for 2 hours, and then is cooled to obtain Zn with a single-shell dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

4. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles are characterized in that ZnFe-ZIF precursor with a solid dodecahedron structure is annealed for 2 hours when the temperature is raised to 400 ℃ at the speed of 2 ℃/min in the air atmosphere, then is annealed for 1 hour when the temperature is raised to 450 ℃ at the speed of 20 ℃/min, and is cooled to obtain Zn with a double-shell dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

5. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles, characterized in that the zinc source is zinc acetate and the iron source is ferrous sulfate heptahydrate.

6. Zn of dodecahedron structure according to claim 1_1-xFe_xO nanoparticles are characterized in that the molar ratio of the zinc source to the iron source is 9: 1-1: 1.

7. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles are characterized in that the total concentration of a zinc source and an iron source in the zinc-iron source liquid is 0.2-0.35 mol/L.

8. Zn of dodecahedron structure according to claim 1_1-xFe_xO nanoparticles, characterized in that the concentration of the 2-methylimidazole solution is 2.2-3.2 mol/L.

9. Zn of dodecahedron structure according to claim 1_1-xFe_xO nano-particles, characterized in that zinc-iron source solution and 2-methylimidazole solution are mixed according to the volume ratio of 1: 1.

Technical Field

The invention relates to the technical field of nano material production, in particular to Fe-doped ZnO nano particles with a dodecahedron structure.

Background

Zinc oxide (ZnO), which is an n-type semiconductor material having a wide band gap of 3.37 eV, is widely used in a variety of fields such as solar energy, gas sensors, spintronics, photonics, and photocatalysis due to its advantages such as non-toxicity, excellent chemical stability, high electron mobility, and structural adjustability. Further, doping ZnO with various elements, such as noble metals, rare metals, transition metals, etc., is reported to be a useful method for improving conductivity when used in gas sensing devices. Iron (Fe) is one of the most common elements in nature; and the d-orbital electron of Fe easily overlaps with the ZnO valence band. When Fe is doped with ZnO, the number of active sites of the material is increased, so that the adsorption of gas elements is facilitated. Therefore, the synthesis of the Fe-doped ZnO material so as to improve the gas-sensitive performance of ZnO has important significance.

The Metal Oxide Framework (MOF) is a novel porous material assembled by inorganic metal nodes and organic ligand molecules, and has good application prospect in the field of sensing due to high porosity, specific surface area and morphological stability. However, the high electrical resistance limits the direct application of MOFs as sensing materials. Thermal annealing of the precursor of the MOF can enable the metal oxide semiconductor to keep the morphology and the porous structure of the MOF, and the high specific surface area enables the MOF-derived oxide semiconductor material to show better gas-sensitive performance. Among MOF derivatives of these metal oxide semiconductors, a hollow multi-shell structure (HoMS) has attracted much attention. This is because MOFs are extremely flexible and their organic ligands and metal components can be separated by fine secondary treatments. Although the MOF derived oxide-based multi-shell structure has great research potential, the research reports are less, and the structure is relatively simple.

Disclosure of Invention

The invention aims to provide Fe-doped ZnO nanoparticles with a dodecahedron structure, which adopt MOF precursors to simplify doping steps, have easily controlled internal structures, can be solid, single-shell and double-shell dodecahedron structures, and have uniform appearance, good dispersity and crystallinity, high surface chemical activity and large specific surface area.

The technical scheme adopted by the invention for solving the technical problems is as follows:

zn with dodecahedron structure_1-xFe_xO nanoparticles, prepared by the following steps:

(1) dissolving a zinc source and an iron source in deionized water, and uniformly stirring and mixing to obtain a zinc-iron source liquid; meanwhile, dissolving 2-methylimidazole in deionized water, and stirring until the 2-methylimidazole is completely dissolved to obtain a 2-methylimidazole solution;

(2) mixing zinc-iron source solution and 2-methylimidazole solution, homogenizing by stirring, standing at room temperature in a dark place for 12-96 hours, carrying out centrifugal separation after the reaction is finished to obtain precipitate, washing the precipitate with methanol for multiple times, and drying to obtain a ZnFe-ZIF precursor with a solid dodecahedron structure;

(3) annealing ZnFe-ZIF precursor with a solid dodecahedron structure at high temperature of 350-450 ℃ for 1-4 hours, and cooling to obtain Zn with a dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

Annealing the ZnFe-ZIF precursor with the solid dodecahedron structure for 2 hours at the temperature of 2-20 ℃/min and the temperature of 350 ℃ in the air atmosphere, and cooling to obtain Zn with the solid dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

Heating a ZnFe-ZIF precursor with a solid dodecahedron structure to 400 ℃ at the speed of 2 ℃/min in the air atmosphere, annealing for 2 hours, and cooling to obtain Zn with a single-shell dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

Heating a solid dodecahedron-structured ZnFe-ZIF precursor to 400 ℃ at a speed of 2 ℃/min in the air atmosphere, annealing for 2 hours, heating to 450 ℃ at a speed of 20 ℃/min, annealing for 1 hour, and cooling to obtain the double-shell dodecahedron-structured Zn_{1- x}Fe _xAnd (3) O nanoparticles. Zn of double-shell dodecahedron structure as the most preferable structure_1-xFe_xCompared with solid and single-shell structures, the O nano-particles have larger specific surface area and more pores, Fe is doped in ZnO in a +2 valence form, the shape of the O nano-particles is a uniform hollow dodecahedron structure, the diameter of the O nano-particles is about 1.0-1.2 mu m, and the O nano-particles are used as a gas sensor, the more active sites on the surface of the material are, the more defects are, the more pores are, and the more defects are beneficial to the reaction of the material and gas molecules²⁺The ions of the valence are,the conductivity is improved, and the method is particularly suitable for being used as a gas sensor material. And ferric iron can not synthesize a dodecahedron hollow structure, and only ferrous iron can be doped into ZnO with the structure.

2-methylimidazole is an organic linker that forms a zeolitic imidazolate framework with the metal Zn/Fe. Zn of single-shell dodecahedral structure_1-xFe _xThe O nanoparticles are hollow structures. Zn_1-xFe_x0.1 ≦ x ≦ 0.5 in O.

The zinc source is zinc acetate, and the iron source is ferrous sulfate heptahydrate.

The molar ratio of the zinc source to the iron source is 9: 1-1: 1. Preferably, the molar ratio of the zinc source to the iron source is 9: 1.

In the zinc-iron source liquid, the total concentration of the zinc source and the iron source is 0.2-0.35 mol/L.

The concentration of the 2-methylimidazole solution is 2.2-3.2 mol/L.

The zinc-iron source solution and the 2-methylimidazole solution are mixed according to the volume ratio of 1: 1.

The Fe-doped ZnO sample prepared by the method has a hexagonal wurtzite structure. The invention uses zinc acetate and ferrous sulfate heptahydrate as metal sources, wherein the ferrous sulfate heptahydrate is used as a doping agent, and adopts simple normal-temperature stirring combined annealing method to prepare Zn_1-xFe_xNanoparticles of an O-dodecahedral structure. Adjustment of annealing conditions to form Zn of different internal structures_1-xFe_xThe O dodecahedral nanoparticles play an important role.

The invention has the beneficial effects that:

1. zn of the invention_1-xFe_xThe O dodecahedron nanoparticles are of hierarchical structures, the doping steps are simplified by adopting the MOF precursor, the internal structure of the material is easy to control, the material can be of solid, single-shell and double-shell dodecahedron structures, the morphology is uniform, the dispersity and the crystallinity are good, the surface chemical activity is high, the specific surface area is large, the electrical conductivity can be improved by doping, and the O dodecahedron nanoparticles have potential application values in the field of gas sensors.

2. The Fe-doped ZnO double-shell dodecahedral nanoparticle prepared by the method has the advantages of cheap and easily-obtained raw materials, simple preparation process, low cost, controllable morphology and structure, good repeatability and the like.

Drawings

FIG. 1 is an X-ray diffraction pattern of the ZnFe-ZIF precursor prepared in example 1;

FIG. 2 is a scanning electron micrograph and a transmission image of the ZnFe-ZIF precursor prepared in example 1; wherein: (a) scanning an electron microscope image; (b) transmitting the picture;

FIG. 3 is Zn of double-shelled dodecahedron structure prepared in example 1_1-xFe_xAn X-ray diffraction pattern of O nanoparticles;

FIG. 4 is Zn of double-shelled dodecahedron structure prepared in example 1_1-xFe_xScanning electron micrographs of O nanoparticles;

FIG. 5 is Zn of double-shelled dodecahedron structure prepared in example 1_1-xFe_xTransmission plot of O nanoparticles;

FIG. 6 is Zn of solid dodecahedral structure prepared in example 2_1-xFe_xTransmission plot of O nanoparticles;

FIG. 7 is a single-shell dodecahedral structure Zn prepared in example 3_1-xFe_xTransmission plot of O nanoparticles.

Detailed Description

The technical solution of the present invention will be further specifically described below by way of specific examples.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified.

Zn with dodecahedron structure_1-xFe_xO nanoparticles, prepared by the following steps:

(1) dissolving a zinc source and an iron source in deionized water, and uniformly stirring and mixing to obtain a zinc-iron source liquid; meanwhile, dissolving 2-methylimidazole in deionized water, and stirring until the 2-methylimidazole is completely dissolved to obtain a 2-methylimidazole solution;

(2) mixing zinc-iron source solution and 2-methylimidazole solution, stirring for homogenization, standing at room temperature in a dark place for reaction for 12-96 hours, centrifugally separating after the reaction is finished to obtain precipitate, washing the precipitate with methanol for 2-5 times, and drying to obtain the ZnFe-ZIF precursor with the solid dodecahedral structure

(3) Annealing ZnFe-ZIF precursor with a solid dodecahedron structure at high temperature of 350-450 ℃ for 1-4 hours, and cooling to obtain Zn with a dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

ZnFe-ZIF precursor with a solid dodecahedron structure is annealed for 2 hours at the temperature rising rate of 2-20 ℃/min and the temperature rising temperature of 350 ℃ in the air atmosphere, and then cooled to obtain Zn with the solid dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

Heating a ZnFe-ZIF precursor with a solid dodecahedron structure to 400 ℃ at the speed of 2 ℃/min in the air atmosphere, annealing for 2 hours, and cooling to obtain Zn with a single-shell dodecahedron structure_1-xFe_xAnd (3) O nanoparticles.

Heating a solid dodecahedron-structured ZnFe-ZIF precursor to 400 ℃ at a speed of 2 ℃/min in the air atmosphere, annealing for 2 hours, heating to 450 ℃ at a speed of 20 ℃/min, annealing for 1 hour, and cooling to obtain the double-shell dodecahedron-structured Zn_{1- x}Fe_xAnd (3) O nanoparticles.

The zinc source is zinc acetate, and the iron source is ferrous sulfate heptahydrate.

The molar ratio of the zinc source to the iron source is 9: 1-1: 1; in the zinc-iron source liquid, the total concentration of the zinc source and the iron source is 0.2-0.35 mol/L. The concentration of the 2-methylimidazole solution is 2.2-3.2 mol/L. The zinc-iron source solution and the 2-methylimidazole solution are mixed according to the volume ratio of 1: 1.

Example 1:

zn with double-shell dodecahedron structure_1-xFe_xThe preparation of O nano-particles comprises the following steps:

(1) 0.26g of C₄H₆O₄Zn·2H₂O was dissolved in 5mL of deionized water, and then 0.04g of FeSO was added₄·7H₂Adding O into the solution, and stirring vigorously until the O is dissolved completely; meanwhile, 1.12g of 2-methylimidazole was dissolved in 5mL of deionized water, and the solution was stirred until completely dissolved. Then, C is quickly removed₄H₆O₄Zn·2H₂O and FeSO₄·7H₂The mixed solution of O was poured into the 2-methylimidazole solution, and homogenized by stirring for 60 seconds. And finally, standing the mixture at room temperature for 48 h in the dark for reaction, after the reaction is finished, centrifugally separating the product, washing the product for 3 times by using methanol, and drying the product to obtain the ZnFe-ZIF precursor with a solid dodecahedron structure, wherein XRD (X-ray diffraction) of the ZnFe-ZIF precursor is shown in an attached figure 1, and SEM (scanning electron microscope) and TEM (transmission electron microscope) figures are shown in a figure 2.

(2) Annealing the solid dodecahedral ZnFe-ZIF precursor prepared in the step (1) at the temperature of 400 ℃ for 2h in an air environment, wherein the heating rate is 2 ℃/min; secondly, the temperature is increased to 450 ℃ at the speed of 20 ℃/min, and then the temperature is kept for 1h to obtain the Zn with the double-shell dodecahedron structure_0.9Fe_0.1The XRD, SEM and TEM of the O nanoparticles are shown in figures 3-5.

As can be seen from FIG. 1, the prepared ZnFe-ZIF precursor with a solid dodecahedron structure has the same structure as ZIF-8, and the morphology characterization result shows that the ZnFe-ZIF precursor has smooth surface and uniform size, and is a solid dodecahedron structure with the average grain diameter of about 1.2 mu m. XRD results after annealing showed Zn_1-xFe_xThe O sample has a hexawurtzite structure, has a space group of P63mc (JCPDS36-1451), does not have redundant miscellaneous peaks, has stronger peak intensity, and indicates the Zn of the invention_0.9Fe_0.1The crystallinity of the O sample is good; the appearance and the size of the sample are not obviously changed, the surface of the sample is roughened, and the sample is assembled by primary nano particles, and the size of the sample is about 1.0-1.2 mu m.

Example 2:

zn of solid dodecahedral structure_1-xFe_xThe preparation of O nano-particles comprises the following steps:

(1) 0.26g of C₄H₆O₄Zn·2H₂O was dissolved in 5mL of deionized water, and then 0.04g of FeSO was added₄·7H₂Adding O into the solution, and stirring vigorously until the O is dissolved completely; meanwhile, 1.12g of 2-methylimidazole was dissolved in 5mL of deionized water, and the solution was stirred until completely dissolved. Then, C is quickly removed₄H₆O₄Zn·2H₂O and FeSO₄·7H₂Pouring the mixed solution of O into the 2-methylimidazoleThe oxazole solution was homogenized by stirring for 60 seconds. And finally, standing the mixture at room temperature for 48 h in the dark for reaction, after the reaction is finished, centrifugally separating the product, washing the product for 3 times by using methanol, and drying the product to obtain the ZnFe-ZIF precursor with a solid dodecahedron structure, wherein XRD (X-ray diffraction) of the ZnFe-ZIF precursor is shown in an attached figure 1, and SEM (scanning electron microscope) and TEM (transmission electron microscope) figures are shown in a figure 2.

(2) Annealing the ZnFe-ZIF precursor with the solid dodecahedron structure prepared in the step (1) at the temperature of 350 ℃ for 2h in the air environment to obtain Zn with the solid dodecahedron structure_0.9Fe_0.1O-nanoparticles, the TEM image of which is shown in FIG. 6.

Example 3:

zn of single-shell dodecahedral structure_1-xFe_xThe preparation of O nano-particles comprises the following steps:

(1) 0.26g of C₄H₆O₄Zn·2H₂O was dissolved in 5mL of deionized water, and then 0.04g of FeSO was added₄·7H₂Adding O into the solution, and stirring vigorously until the O is dissolved completely; meanwhile, 1.12g of 2-methylimidazole was dissolved in 5mL of deionized water, and the solution was stirred until completely dissolved. Then, C is quickly removed₄H₆O₄Zn·2H₂O and FeSO₄·7H₂The mixed solution of O was poured into the 2-methylimidazole solution, and homogenized by stirring for 60 seconds. And finally, standing the mixture at room temperature for 48 h in the dark for reaction, after the reaction is finished, centrifugally separating the product, washing the product for 3 times by using methanol, and drying the product to obtain the ZnFe-ZIF precursor with a solid dodecahedron structure, wherein XRD (X-ray diffraction) of the ZnFe-ZIF precursor is shown in an attached figure 1, and SEM (scanning electron microscope) and TEM (transmission electron microscope) figures are shown in a figure 2.

(2) Annealing the solid dodecahedron-structured ZnFe-ZIF precursor prepared in the step (1) at the temperature of 400 ℃ for 2h in an air environment at the heating rate of 2 ℃/min to obtain single-shell dodecahedron-structured Zn_0.9Fe_0.1O-nanoparticles, the TEM image of which is shown in FIG. 7.

Comparative example 1

This example is different from example 1 in that FeSO₄·7H₂O was replaced by ferric sulfate, otherwise the same as in example 1. Finally, Zn with a double-shell dodecahedron structure cannot be prepared_1-xFe_xAnd (3) O nanoparticles.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.