Synthesis of water stable hybrid bismuth iodine material and its application in photocatalytic reduction of co2

Abstract

The application discloses an inorganic-organic bismuth iodine hybrid semiconductor and a preparation method and application thereof, the hybrid semiconductor has a molecular formula of (Me2biz)BiI4, wherein (Me2biz) + is a methylated benzimidazole cation with a positive charge, (BiI4) ‑ in the material is a one-dimensional anion chain formed by coordination of trivalent bismuth ions and iodine ions, and a single crystal of the compound (Me2biz)BiI4 is obtained by selecting bismuth iodide, benzimidazole, methanol, acetone and hydroiodic acid as reaction raw materials and solvents and under a solvothermal reaction condition, and the single crystal has good stability and photocatalytic CO2 reduction catalytic activity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor photocatalytic CO2 reduction, and particularly relates to a bismuth-iodine-based hybrid material (Me2biz)BiI4 with high water stability and application of the bismuth-iodine-based hybrid material (Me2biz)BiI4 in photocatalytic CO2 reduction, wherein Me2biz is a methylated benzimidazole. BACKGROUND

[0002] Inorganic-organic hybrid perovskite material is a kind of composite material formed by the interaction of inorganic perovskite crystal and organic molecules. Both the organic component and the inorganic component in the material can be replaced, so that the types of hybrid perovskite materials are very rich, and the structures are diversified, so that the band gap and performance can be regulated through structure regulation. The rich crystal structure makes the hybrid perovskite material have a series of unique material properties, including low carrier rate, adjustable absorption spectrum, high carrier mobility and low defect density. In addition, it also has the advantages of simple synthesis, low cost, low light-emitting threshold and high light-emitting conversion efficiency. It has wide application prospects in the fields of catalysis, superconductivity and photoelectricity, and has become a hot spot in current material science research.

[0003] Photocatalytic CO2 reduction technology is attracting attention due to its high efficiency, low energy consumption and high selectivity. However, there are still some problems and challenges in current CO2 reduction technology. Traditional catalysts usually have low activity and selectivity, complex reaction conditions, and the stability and life of the catalysts need to be improved. Therefore, it is necessary to develop a new type of photocatalyst with high CO2 reduction activity and selectivity, and good stability to promote the development of photocatalytic CO2 reduction technology. SUMMARY

[0004] The purpose of the present application is to provide a bismuth-iodine inorganic-organic hybrid semiconductor material with high water stability, which can carry out photocatalytic CO2 reduction in pure water solution. Using bismuth iodide as the inorganic component solves the problem of lead toxicity of lead-based perovskite material, and methylated benzimidazole is selected as the organic cation. The introduction of methyl greatly improves the water stability of the material. The synthesis method of the material is simple, the material itself has the characteristics of low cost, non-toxicity, excellent stability and good photocatalytic performance.

[0005] The technical scheme of the present application includes the following contents:

[0006] 1. An inorganic-organic bismuth-iodine hybrid semiconductor (Me2biz)BiI4, wherein (Me2biz) in the formula represents a dimethylated benzimidazole cation formed by combining a methyl group with a nitrogen atom in benzimidazole. The compound crystallizes in a triclinic system, P-1 space group, and the unit cell parameters are a = 8. 1 A, b = 8. 1 A, c = 15. 1 A, a = 71. 9°, b = 78. 9°, and g = 63. 9°. + ​α = 79.15(4)°, β = 77.92(4)°, γ = 72.08(4)°. The material appears as red needle-like crystals, and the structure type is an ionic inorganic-organic hybrid material, and the structural feature is that the cation part is composed of methylated benzimidazole cations with a unit positive charge, and the anion part is a one-dimensional chain structure formed by coordination of trivalent bismuth ions and iodine ions. Such structure can balance the positive charge of the methylated benzimidazole cation, so that the whole material is electrically neutral.

[0007] 2. The preparation method of the inorganic-organic bismuth iodine hybrid semiconductor according to claim 1, wherein iodized bismuth and benzimidazole are weighed and dissolved in a mixed solution of hydriodic acid, methanol and acetone with a volume ratio of 3:10:50, and a red crystalline product (Me2biz)BiI4 can be obtained under a solvothermal condition.

[0008] 3. The use of the inorganic-organic bismuth iodine hybrid semiconductor according to claim 1, wherein the compound has excellent water stability and photocatalytic CO2 reduction performance, and is used as a CO2 reduction photocatalyst.

[0009] The product has simple and controllable synthesis conditions, is pollution-free, realizes alkylation of benzimidazole and inorganic (BiI4) - The anion chain is combined at the molecular level, has good water stability, can directly perform a photocatalytic CO2 reduction reaction in an aqueous solution, has excellent selectivity, and the product is only CO, and the yield is 2.208 μmol·g -1 ·h -1 . BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a molecular structure diagram of the inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4.

[0011] Figure 2 It is a partial structure diagram of a one-dimensional anion chain in the inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4 molecule.

[0012] Figure 3 It is a space packing diagram of the inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4 molecule along the a axis in a unit cell.

[0013] Figure 4 It is a powder diffraction pattern of the inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4 just synthesized, which is completely consistent with the powder simulation diffraction result.

[0014] Figure 5 It is an infrared spectrum diagram of the inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4.

[0015] Figure 6 Solid UV absorption spectrum of inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4.

[0016] Figure 7 Thermogravimetric analysis of inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4.

[0017] Figure 8 Stability test of inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4, the powder diffraction pattern still matches the original sample diffraction results completely after 237 days under UV lamp and 75% relative humidity conditions.

[0018] Figure 9 a Photocatalytic CO2 reduction reaction 5h gas chromatogram of inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4; Figure 9 b Inorganic-organic bismuth iodine hybrid semiconductor (Me2biz)BiI4 continuous three times repeated catalytic experiment yield-time relationship diagram. DETAILED DESCRIPTION

[0019] (1) Synthesis of compound (Me2biz)BiI4

[0020] 0.236g BiI3 and 0.054g benzimidazole were put into a quartz reaction bottle with a 25mL polytetrafluoroethylene liner, 0.3mL hydroiodic acid, 1mL methanol and 5mL acetonitrile were added, then the polytetrafluoroethylene liner was put into a stainless steel reaction kettle, tightly screwed and placed in the lower layer of the oven at 120℃, and kept at this temperature for three days, then cooled to room temperature, washed with ethanol to obtain red transparent needle-like crystals, which are compound (Me2biz)BiI4. The purity and yield of the crystals obtained under the above reaction conditions are high.

[0021] (2) Stability test of compound (Me2biz)BiI4

[0022] 10mg of (Me2biz)BiI4 crystal powder was ground, a small amount of anhydrous ethanol was added and ball milled for 30min, then uniformly dropped and coated on a quartz plate, and after baking with a baking lamp, it was placed under a UV lamp for continuous irradiation. Another piece was placed in a 75% relative humidity environment for storage, and after 237 days, X-ray powder diffraction test was performed.

[0023] (3) Compound (Me2biz)BiI4 for photocatalytic CO2 reduction

[0024] In a closed reaction cell, 50 mg of finely ground (Me2biz)BiI4powder was dispersed in 80 mL of pure water solution, and high-purity CO2gas was bubbled for 30 min to remove air in the reaction cell and solution and to achieve CO2gas saturation. Irradiation was performed for 5 h using a 300 W Xe lamp (λ≥420 nm) with a light power density of 100 mW-cm -2 The sample was tested every hour using gas chromatography.

Claims

1. An inorganic-organic bismuth-iodine hybrid semiconductor (Me2biz)BiI4, wherein Me2biz represents a methylated benzimidazole cation, the bismuth-iodine hybrid semiconductor being crystallized in a triclinic crystal system, space group P-1, with unit cell parameters of... α = 79.15(4)°, β = 77.92(4)°, γ = 72.08(4)°, the crystal color is red, exhibiting an ionic hybrid structure, in which the cation is (Me2biz). + The cation is formed by dimethylation of the nitrogen atom of benzimidazole, and the anion is formed by (BiI6). 3- (BiI4) formed by connecting octahedrons with shared edges - An anionic chain, comprising trivalent hexacoordinate bismuth ions and monodentate and bidentate iodide ions, extends along the a-axis and fills (Mebiz) space. + In the pores formed by the accumulation of cations.

2. A method for preparing the inorganic-organic bismuth-iodine hybrid semiconductor according to claim 1, characterized in that: BiI3 and benzimidazole were placed in a mixed solution of hydroiodic acid, methanol and acetonitrile, and reacted at a constant temperature of 120°C for three days. After cooling to room temperature, red transparent needle-like crystals were obtained, which were the compound (Me2biz)BiI4.

3. The use of the inorganic-organic bismuth-iodine hybrid semiconductor of claim 1 for photocatalytic CO2 reduction.

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