CN112619709A - Photocatalytic nano material and preparation method thereof - Google Patents

Abstract

The present invention proposes a mixed band gap halide perovskite nanomaterial, which comprises a metal organic framework material and a halide perovskite nanoparticle; the halide perovskite nanoparticle is embedded in the metal organic framework in the pores of the material; the metal-organic framework material is a porous crystal material formed by metal transition ions and organic ligands; the band gap of the halide perovskite nanoparticles gradually decreases from the outside to the inside; the perovskite The surface layer of the mineral nanoparticles is FAPbBr ₃ , and the inner core is FAPbI ₃ . The above-mentioned photocatalytic nanomaterials can significantly improve the water vapor stability of halide perovskite nanoparticles; they can efficiently absorb and utilize sunlight of different energies, and have high "photo-chemical energy" conversion efficiency. This photocatalytic technology has great application prospects in the field of environmental pollution, especially the photocatalytic treatment of _CO . The invention also discloses its preparation method.

Description

Photocatalytic nanomaterial and preparation method thereof

technical field

The invention belongs to the technical field of CO ₂ photocatalysis, and in particular relates to a photocatalytic nanomaterial and a preparation method thereof.

Background technique

At the same time that global warming is more and more widely concerned, CO ₂ emission reduction has become a hot topic, because it is related to the future and destiny of human living environment, direct light-driven carbon dioxide emission reduction, high value-added chemical raw materials using high-efficiency catalysts Or fuel is one of those fascinating technologies. During artificial photosynthesis, a crucial challenge is to design efficient and low-cost catalysts and photosensitizers. In this context, a series of semiconductor nanocrystals have been pursued as photosensitizers because of their large extinction coefficients, flexible thermodynamic tuning, and particle-tuned optical properties. As a new type of optoelectronic functional materials, halide perovskites have been widely studied in many fields such as solar cells, light-emitting diodes, photodetectors, and photocatalysis, and have made significant research progress. Due to its low cost and simple synthesis method, perovskites also have very broad application prospects in the field of photocatalytic carbon dioxide reduction.

However, the stability and "photo-chemical energy" conversion efficiency of photocatalytic materials have become an urgent problem to be solved.

SUMMARY OF THE INVENTION

The present invention provides a new photocatalytic nanomaterial.

A photocatalytic nanomaterial, comprising a metal organic framework material and halide perovskite nanoparticles; the halide perovskite nanoparticles are embedded in the pores of the metal organic framework material;

The metal-organic framework material is a porous crystalline material formed by metal transition ions and organic ligands;

The band gap of the halide perovskite nanoparticles gradually decreases from the outside to the inside; preferably, the surface layer of the perovskite nanoparticles is FAPbBr ₃ , and the inner core is FAPbI ₃ .

In the above photocatalytic nanomaterials, the halide perovskite nanoparticles are embedded in the pores of the metal organic framework material, so the water vapor stability of the halide perovskite nanoparticles is significantly improved; the halide perovskite nanoparticles The band gap of the nanoparticle gradually decreases from the outside to the inside, which can efficiently absorb and utilize sunlight of different energies, and has a high "photo-chemical energy" conversion efficiency.

In one specific embodiment, the general chemical formula of the halide perovskite nanoparticles is FAPb(I _{1- x} Br _x ) ₃ , wherein 0≤x≤1.

In one specific embodiment, the transition metal ion is a zinc ion, and the organic ligand is a porphyrin-based organic compound or an imidazole-based organic compound.

The invention also provides a preparation method of the photocatalytic nanomaterial.

A preparation method of a photocatalytic nanomaterial, comprising the following steps:

Preparation of metal organic framework material MOFs;

Loading PbI ₂ on the metal-organic framework material to obtain the first product PbI ₂ @MOFs;

The first product PbI ₂ @MOFs; react with FAI to obtain the second product FAPbI ₃ @MOFs;

The second product FAPbI ₃ @MOFs is subjected to ion exchange treatment with FABr to obtain FAPb(I _1-x Br _x ) ₃ @MOFs perovskite nanomaterials with mixed band gaps.

The photocatalytic nanomaterial obtained by the above preparation method can significantly improve the water vapor stability of the halide perovskite nanoparticles; it can efficiently absorb and utilize sunlight of different energies, and has a high "photo-chemical energy" conversion efficiency.

In one specific embodiment, the step of performing ion exchange treatment on the second product and FABr includes: soaking the second product in a FABr solution.

In one specific embodiment, the FABr solution is an isopropanol solution of FABr; the concentration of the FABr is 18g/L-22g/L.

In one of the specific embodiments, the soaking time is 1-20min.

In one of the specific embodiments, the metal organic framework material is synthesized by hydrothermal reaction.

In one specific embodiment, the step of loading PbI ₂ on the metal-organic framework material includes: soaking the metal-organic framework material in a PbI ₂ solution for more than one hour.

In one of the specific embodiments, the step of reacting the first product with FAI includes: soaking the first product in the FAI solution for 8-12 minutes.

Description of drawings

FIG. 1 is a schematic structural diagram of the metal organic framework of the present invention.

Figure 2 is a schematic diagram of the halide perovskite nanoparticles of the present invention.

FIG. 3 is a band gap diagram of the halide perovskite perovskite nanoparticles in FIG. 2 .

FIG. 4 is a schematic structural diagram of the photocatalytic nanomaterial of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

A photocatalytic nanomaterial, comprising a metal organic framework material and halide perovskite nanoparticles; the halide perovskite nanoparticles are embedded in the pores of the metal organic framework material;

The metal-organic framework material is a porous crystalline material formed by a metal transition ion and an organic ligand; a soluble metal salt and an imidazole compound are mixed and reacted in an organic solvent to obtain a metal-organic framework material, and the soluble metal salt is selected from soluble metal halide. One or more of soluble metal nitrates, soluble metal acetates and soluble metal sulfates.

As shown in Figure 1, 11 is a transition metal ion and 12 is an organic ligand. 11 and 12 form metal organic frameworks by bonding.

The band gap of the halide perovskite nanoparticle gradually decreases from the outside to the inside; the surface layer of the perovskite nanoparticle is FAPbBr ₃ , and the inner core is FAPbI ₃ .

Figure 2 is a schematic diagram of a mixed bandgap perovskite nanoparticle. In its outermost layer 21, x=1, that is, only Br and no I; in its inner core 22, x=0, that is, only I and no Br. FIG. 3 is a band gap diagram of the halide perovskite perovskite nanoparticles in FIG. 2 . 21 denotes the outer band gap, and 22 denotes the inner band gap.

Referring specifically to FIG. 4, FIG. 4 is a molecular structure diagram of the photocatalytic nanomaterial of the present invention. The halide perovskite nanoparticles are embedded in the pores of the metal organic framework material; that is, the metal organic framework material is wrapped outside the halide perovskite nanoparticles. In this way, the metal organic framework material protects the halide perovskite nanoparticles and improves the water vapor stability of the halide perovskite nanoparticles. The band gap of the halide perovskite nanoparticles gradually decreases from the outside to the inside, the outermost layer is pure FAPbBr ₃ , the band gap can reach 2.3eV, and the innermost layer is FAPbI ₃ , and the band gap is 1.48eV. This hybrid bandgap FAPbI _{1- xBrx} @ZIF-8 nanomaterial can absorb sunlight in a wider energy range

Among them, metal organic framework materials are generally abbreviated as MOFs. The metal in the metal organic framework material may be Re, Co, Fe, Ni, Mn, Mo, W, Ru, Os, Rh, Ir, Pd, Zn, Cr, Cu, and the like. The complexes include, but are not limited to, complexes functionalized with carboxyl, phosphoric acid, amino and other groups. The complex may specifically be a polypyridine complex, a porphyrin complex, an imidazole complex, a thiol complex, an azacyclic carbene complex or other forms of complexes.

In one embodiment, the transition metal ion in the metal organic framework material is a zinc ion, and the organic ligand is a porphyrin-based organic compound or an imidazole-based organic compound. More preferably, the metal organic framework material is sodalite zinc methylimidazolium (ZIF-8).

In one specific embodiment, the general chemical formula of the halide perovskite nanoparticles is FAPb(I _{1- x} Br _x ) ₃ , wherein 0≤x≤1. With different positions and different x values, the band gap of the halide perovskite gradually changes, so that it can absorb light in different wavelength bands and has a high "photo-chemical energy" conversion efficiency.

In the above photocatalytic nanomaterials, the halide perovskite nanoparticles are embedded in the pores of the metal organic framework material, so the water vapor stability of the halide perovskite nanoparticles is significantly improved; the halide perovskite nanoparticles The band gap of the nanoparticle gradually decreases from the outside to the inside, which can efficiently absorb and utilize sunlight of different energies, and has a high "photo-chemical energy" conversion efficiency.

The invention also provides a preparation method of the photocatalytic nanomaterial.

A preparation method of a photocatalytic nanomaterial, comprising the following steps:

Mixing and reacting soluble metal salts, metal oxide nanosheets and imidazole compounds in organic solvents to obtain metal-organic framework material MOFs;

Loading PbI ₂ on the metal-organic framework material to obtain the first product PbI ₂ @MOFs;

The first product PbI ₂ @MOFs; react with FAI to obtain the second product FAPbI ₃ @MOFs;

The second product FAPbI ₃ @MOFs is subjected to ion exchange treatment with FABr to obtain FAPb(I _1-x Br _x ) ₃ @MOFs perovskite nanomaterials with mixed band gaps.

Wherein, the soluble metal salt, the metal oxide nanosheet and the imidazole compound are mixed and reacted in an organic solvent to obtain a metal-organic framework material; preferably, the metal-organic framework material is synthesized by a hydrothermal reaction.

The purpose of loading PbI ₂ is to introduce PbI ₂ into the pores of the metal organic framework material. Preferably, the step of loading PbI ₂ on the metal-organic framework material includes: soaking the metal-organic framework material in a PbI ₂ solution for more than one hour.

The purpose of the reaction between the first product and FAI is to react PbI ₂ embedded in the pores of the metal organic framework material with FAI to convert PbI ₂ into FAPbI ₃ ; and FAPbI ₃ is still embedded in the pores of the metal organic framework material. middle. Preferably, the step of reacting the first product with FAI includes: soaking the first product in the FAI solution for 8-12 min.

Among them, the purpose of the ion exchange treatment is that the iodide ions in the FAPbI ₃ nanoparticles embedded in the pores of the metal organic framework are ion-exchanged with bromide ions, that is, the bromide ions migrate into the FAPbI ₃ nanoparticles, while the original FAPbI ₃ The iodide ions in the nanoparticles partially migrate out, that is, the iodide ions in some positions become bromide ions, the surface layer migrates faster and the ion exchange is more substrate, while the inner layer migrates slowly and the ion exchange is insufficient; The surface layer of perovskite nanoparticles is FAPbBr ₃ , the inner layer is FAPbI ₃ , and the intermediate part between the two is a mixture of iodide ions and bromide ions, but the contents of the two are different in different regions, resulting in different regions. Halide perovskite nanoparticles have variable band gaps.

Preferably, the step of subjecting the second product to FABr ion exchange treatment comprises: soaking the second product in a FABr solution.

More preferably, the FABr solution is an isopropanol solution of FABr; the concentration of the FABr is 18g/L-22g/L.

In one specific embodiment, the soaking time is 10 minutes.

The photocatalytic nanomaterial obtained by the above preparation method can significantly improve the water vapor stability of the halide perovskite nanoparticles; it can efficiently absorb and utilize sunlight of different energies, and has a high "photo-chemical energy" conversion efficiency.

The present invention will be further elaborated below in conjunction with specific embodiments.

Example 1

Synthetic metal organic framework material ZIF-8:

Dissolve 717 mg of Zn(NO ₃ ) ₂ 6H ₂ O (zinc nitrate hexahydrate) and 180 mg of H-MeIM (2-methylimidazole) in 50 mL of DMF; After heating to 150°C at a heating rate of min, the solution was kept for 24 hours, and then cooled to room temperature naturally.

After removing the supernatant, 50 mL of chloroform was added to obtain colorless crystal particles. The colorless crystal particles were washed three times with DMF and then dried to obtain the metal organic framework material ZIF-8.

To prepare the first product:

The metal-organic framework material ZIF-8 was soaked in a 1 mmol/L PbI ₂ solution (the solvent was a 1:9 mixed solvent of DMF and ethanol) for one hour. After filtering, washing with a mixed solvent of DMF:ethanol=1:1 and drying to obtain the first product.

Prepare the second product:

The first product was soaked in the isopropanol solution of 10 mg/mL FAI, and after 10 min, filtered, washed with isopropanol, and dried to obtain the second product.

Synthetic final product:

The second product was soaked in the isopropanol solution of 20 mg/mL FABr, after 10 min, filtered, washed with isopropanol, and dried to obtain the photocatalytic nanomaterial.

The embodiments of the present application have been described above, but the present application is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative rather than restrictive. Under the inspiration, without departing from the scope of protection of the purpose and claims of the present application, many forms can be made, which all fall within the protection of the present application.

Claims (10)

1. a photocatalytic nanomaterial, is characterized in that, comprises metal organic framework material and halide perovskite nanoparticle; Described halide perovskite nanoparticle is embedded in the pore of described metal organic framework material; The metal-organic framework material is a porous crystalline material formed by metal transition ions and organic ligands; The band gap of the halide perovskite nanoparticles gradually decreases from the outside to the inside; The chemical formula of the halide perovskite nanoparticles is FAPb(I _1-x Br _x ) ₃ , wherein 0≤x≤1; The band gaps of the halide perovskite nanoparticles range from 1.48 eV to 2.3 eV. 2 . The photocatalytic nanomaterial according to claim 1 , wherein the surface layer of the perovskite nanoparticles is FAPbBr ₃ , and the inner core is FAPbI ₃ . 3 . 3. photocatalytic nanomaterial according to claim 1, is characterized in that, described transition metal ion is a kind of in zinc ion, iron ion, copper ion, cobalt ion, and described organic ligand is porphyrin organic matter or imidazole organics. 4. The photocatalytic nanomaterial according to claim 1, wherein the metal organic framework material is ZIF-8. 5. a preparation method of photocatalytic nanomaterial, is characterized in that, comprises the steps: Preparation of metal organic framework materials; Loading PbI ₂ on the metal organic framework material to obtain the first product with the first product; react with FAI to obtain the second product; The second product is ion-exchanged with FABr. 6 . The preparation method according to claim 5 , wherein the metal-organic framework is prepared by mixing and reacting a soluble metal salt and an imidazole compound in an organic solvent. 7 . 7 . The preparation method according to claim 5 , wherein the step of performing ion exchange treatment on the second product and FABr comprises: soaking the second product in a FABr solution. 8 . 8. preparation method according to claim 7, is characterized in that, described FABr solution is the isopropanol solution of FABr; The concentration of described FABr is 18g/L-22g/L; The duration of described soaking is 1- 20min. 9 . The preparation method according to claim 5 , wherein the step of loading PbI ₂ on the metal organic framework material comprises: soaking the metal organic framework material in a PbI ₂ solution for more than one hour. 10 . 10 . The preparation method according to claim 5 , wherein the step of reacting the first product with FAI comprises: soaking the first product in an FAI solution for 8-12 min. 11 .

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