A method for synthesizing bismuthyl iodide

Abstract

The application discloses a method for synthesizing bismuth oxyiodide, and belongs to the technical field of photocatalyst synthesis, and is completed according to the following steps: a mixed solution of KI-HNO3 with a concentration of 6 mM is prepared by using solid potassium iodide and concentrated nitric acid; 0.5 g of bismuth oxide microrods is added into 2 mL of the above solution, the obtained suspension is stirred on a magnetic stirrer for 10 minutes, the obtained solid product is obtained through centrifugal separation and is dried in a 60 DEG C oven, so that bismuth oxyiodide is obtained, and the product can be stored in a sealed and light-proof reagent bottle. In the application, the operation process of the method for preparing bismuth oxyiodide is simpler and more economical, solid bismuth oxide is easier to store compared with bismuth nitrate or bismuth halide solution, the solid bismuth oxide can be taken as needed, and the final structure of BiOI formed through Bi2O3 microrods is limited by the initial Bi2O3 structure; meanwhile, the dispersed microrods can provide more specific surface area, so that a faster catalytic reaction is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of synthesis of photocatalysts, in particular to a method for synthesizing bismuth oxyiodide. BACKGROUND

[0002] Semiconductor photocatalysts can realize the separation of their own electron-hole by obtaining energy from light. The electrons and holes in the catalysts mostly recombine and annihilate, while the electrons and holes reaching the surface can initiate reduction and oxidation reactions. If sunlight is used as the light source, theoretically, photocatalytic technology can realize the performance of endothermic reactions without additional energy sources, so as to achieve the purpose of energy conversion and storage, and become a green technology. However, the reality is that there are not many photocatalysts that can directly use sunlight. For example, the most classic photocatalyst, titanium dioxide (TiO2), mainly absorbs light with a wavelength shorter than 410 nanometers, that is, ultraviolet light; and in the solar spectrum, the energy of ultraviolet light accounts for only 3%. In comparison, bismuth oxyiodide (BiOI) has a relatively narrow band gap, about 1.9 eV; which makes its light absorption boundary extend to 650 nanometers, covering most of the visible light (the proportion of visible light energy in sunlight is 42%). That is, under the same intensity of sunlight, the potential photocatalytic efficiency of BiOI is much higher than that of TiO2. So far, BiOI has been applied as a photocatalyst in various fields such as pollutant treatment, sterilization, and manufacturing of light-driven micro-motors.

[0003] The preparation of BiOI usually uses compounds containing trivalent bismuth [Bi(III)] as precursors, such as bismuth nitrate, bismuth halide, etc. In an aqueous solution containing iodide ions, partial hydrolysis of bismuth ions can generate BiOI.

[0004] When bismuth nitrate or bismuth halide is used as a precursor to synthesize BiOI, it is necessary to first prepare an aqueous solution of bismuth nitrate or bismuth halide, and then introduce potassium iodide (KI) solution into the solution to obtain BiOI product. The rapid hydrolysis reaction of trivalent bismuth ions in the bismuth nitrate or bismuth halide solution makes it difficult to control the nanostructure due to the lack of micro bismuth-containing components in the solution. That is, the synthesis of BiOI using bismuth nitrate or bismuth halide as a precursor usually tends to give irregular block structures. SUMMARY

[0005] The purpose of the present application is to provide a method for synthesizing bismuth oxyiodide to solve the technical problems in the prior art that when bismuth nitrate or bismuth halide is used as a precursor to synthesize BiOI, it is necessary to first prepare an aqueous solution of bismuth nitrate or bismuth halide, which is easy to form irregular block structures, and the production process is not simple and economical.

[0006] The present application provides a method for synthesizing bismuth oxyiodide, which is completed according to the following steps:

[0007] A mixture solution of KI-HNO3 with a concentration of 6 mM was prepared using solid potassium iodide (KI) and concentrated nitric acid (HNO3); 0.5 g of bismuth oxide microrods was added into 2 mL of the mixture solution of KI-HNO3 with a concentration of 6 mM, and the obtained suspension was stirred on a magnetic stirrer for 10 minutes, then the obtained solid product was obtained by centrifugal separation and dried in an oven at 60 ℃, and the obtained product after drying was the finished product of bismuth oxyiodide, which could be stored in a sealed, light-proof reagent bottle.

[0008] Compared with the prior art, the present application has the following beneficial effects:

[0009] Firstly, the method for preparing bismuth oxyiodide in the present application has a simpler and more economical operation process, and compared with bismuth nitrate or bismuth halide solution, solid bismuth oxide is easier to store, and can be taken as needed without the need for additional preparation of a bismuth-containing solution; and the ordered assembly of the BiOI nanosheets obtained by the method can form a rod-like structure similar to the Bi2O3 microrods, compared with the irregular block structure of BiOI synthesized by using bismuth nitrate or bismuth halide as a precursor to prepare an aqueous solution thereof in the traditional method, in the present application, the mixed solution of KI and nitric acid is directly added dropwise into the precursor bismuth oxide microrods, and the BiOI product with a rod-like structure can be obtained, since the bismuth ions are slowly released from the outside to the inside of the Bi2O3 solid, the BiOI is gradually generated only around the solid and cannot grow unlimitedly outward, and the final structure of the BiOI is limited by the initial Bi2O3 structure, at the same time, the dispersed microrods can provide more specific surface area, so that a faster catalytic reaction can be achieved.

[0010] Secondly, the BiOI microrods have more possibilities in subsequent processing and application compared with the BiOI obtained by the traditional method, for example, the suspension of the BiOI microrods can be spin-coated on a glass or polymer carrier to more easily form a flat film. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0012] Figure 1 Schematic diagram of the route for synthesizing BiOI (wherein, route A is a schematic diagram of the synthesis of the prior art route, and route B is a schematic diagram of the synthesis method in the present application);

[0013] Figure 2Scanning electron microscope image of the product of iodized bismuthyl oxide obtained in the prior art;

[0014] Figure 3 Scanning electron microscope image of the product of iodized bismuthyl oxide obtained in the present application using 6 mM KI-HNO3 mixed solution;

[0015] Figure 4 Scanning electron microscope image and corresponding element distribution map of the product of iodized bismuthyl oxide obtained in the present application using 6 mM KI-HNO3 mixed solution;

[0016] Figure 5 UV-Vis diffuse reflectance absorption spectrum of the product of iodized bismuthyl oxide obtained in the present application using 6 mM KI-HNO3 mixed solution;

[0017] Figure 6 X-ray diffraction spectrum of the product of iodized bismuthyl oxide obtained in the present application using 6 mM KI-HNO3 mixed solution;

[0018] Figure 7 Scanning electron microscope image of the product of iodized bismuthyl oxide obtained in the present application using 2 mM KI-HNO3 mixed solution;

[0019] Figure 8 Scanning electron microscope image of the product of iodized bismuthyl oxide obtained in the present application using 4 mM KI-HNO3 mixed solution;

[0020] Figure 9 Scanning electron microscope image of the product of iodized bismuthyl oxide obtained in the present application using 8 mM KI-HNO3 mixed solution. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application.

[0022] The components of the embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0023] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative labor fall within the scope of protection of the present application.

[0024] The following will be described in conjunction with Figures 1 to 9 The embodiments of the present application provide related experiments on the method for synthesizing iodized bismuthyl oxide. The various raw materials used in the embodiments of the present application are not commercially available unless otherwise specified.

[0025] Example 1:

[0026] Raw materials: potassium iodide (KI) solid powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0027] The method for synthesizing bismuth oxyiodide in this example includes the following steps:

[0028] Step one: configure the pre-solution: weigh 12 g of potassium iodide solid powder, and configure the potassium iodide solid powder and 95% concentration of concentrated nitric acid into a KI-HNO3 mixed solution with a concentration of 6 mM;

[0029] Step two: put 0.5 g of bismuth oxide into 2 mL of KI-HNO3 mixed solution with a concentration of 6 mM, and fully react to obtain a suspension;

[0030] Step three: centrifugal stirring: the suspension is fully stirred on a magnetic stirrer for 10 min;

[0031] Step four: drying: after centrifugal separation of the suspension, the lower solid product is placed in an air oven for drying, the drying temperature is 60°C, and after sufficient drying for 1 h, the bismuth oxyiodide product is obtained.

[0032] The scanning electron microscope image of the bismuth oxyiodide obtained in this example 1, from Figure 3 which can be seen that the BiOI presents as dispersed microrods.

[0033] The scanning electron microscope image of the bismuth oxyiodide obtained in this example 1 at different magnifications, from Figure 4 which can be seen that the elements of BiOI are in a uniformly dispersed state.

[0034] The ultraviolet-visible diffuse reflectance absorption spectrum of the bismuth oxyiodide product obtained in this example 1, as shown in Figure 5 , and its X-ray diffraction spectrum is shown in Figure 6 , it can be seen that the obtained BiOI product is indeed a visible light responsive semiconductor, with an absorption boundary of 677 nm, corresponding to a band gap of 1.83 eV, which can be used as an excellent semiconductor photocatalyst.

[0035] Example 2:

[0036] Raw materials: potassium iodide (KI) solid powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0037] In this example, by changing the concentration of KI-HNO3 mixture, bismuth oxyiodide synthesis experiment is carried out, including the following steps:

[0038] Step one: configure the pre-solution: take 12g of potassium iodide solid powder, and configure the potassium iodide solid powder and 95% concentration of concentrated nitric acid into a KI-HNO3 mixed solution with a concentration of 2mM;

[0039] Step two: put 0.5g of bismuth oxide into 2mL of KI-HNO3 mixed solution with a concentration of 2mM, and fully react to obtain a suspension;

[0040] Step three: centrifugal stirring: the suspension is fully stirred on a magnetic stirrer for 10min;

[0041] Step four: drying: after centrifugal separation of the suspension, the lower solid product is placed in an air oven for drying, the drying temperature is 60°C, and after sufficient drying for 1h, the bismuth oxyiodide product is obtained.

[0042] The scanning electron microscope image of the bismuth oxyiodide obtained in this example 2 can be seen from Figure 7 It can be seen that the BiOI appears as dispersed microrods, but the amount of bismuth ions released by the Bi2O3 microrods is less, and the number of obtained bismuth oxyiodide nanosheets is also less.

[0043] Example 3:

[0044] Raw materials: potassium iodide (KI) solid powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0045] In this example, the synthesis experiment of bismuth oxyiodide is carried out again by changing the concentration of KI-HNO3 mixture, including the following steps:

[0046] Step one: configure the pre-solution: take 12g of potassium iodide solid powder, and configure the potassium iodide solid powder and 95% concentration of concentrated nitric acid into a KI-HNO3 mixed solution with a concentration of 4mM;

[0047] Step two: put 0.5g of bismuth oxide into 2mL of KI-HNO3 mixed solution with a concentration of 4mM, and fully react to obtain a suspension;

[0048] Step three: centrifugal stirring: the suspension is fully stirred on a magnetic stirrer for 10min;

[0049] Step four: drying: after centrifugal separation of the suspension, the lower solid product is placed in an air oven for drying, the drying temperature is 60°C, and after sufficient drying for 1h, the bismuth oxyiodide product is obtained.

[0050] The scanning electron microscope image of the bismuth oxyiodide obtained in this example 3 can be seen from Figure 8As can be seen from Table 1, BiOI appears as dispersed microrods, but the amount of bismuth ions released by Bi2O3 microrods is less, and the number of BiOI nanoplates obtained is also less, but there is a significant increase in the amount of bismuth ions and the number of BiOI nanoplates compared to the amount of bismuth ions and the number of BiOI nanoplates in Example 2.

[0051] Example 4:

[0052] Raw materials: potassium iodide (KI) solid powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0053] In this example, the synthesis experiment of BiOI was carried out again by changing the concentration of KI-HNO3 mixture, including the following steps:

[0054] Step one: prepare the pre-solution: weigh 12 g of potassium iodide solid powder, and configure the potassium iodide solid powder and 95% concentrated nitric acid into a KI-HNO3 mixed solution with a concentration of 8 mM;

[0055] Step two: put 0.5 g of bismuth oxide into 4 mL of KI-HNO3 mixed solution with a concentration of 8 mM, and fully react to obtain a suspension;

[0056] Step three: centrifugal stirring: the suspension is fully stirred on a magnetic stirrer for 10 min;

[0057] Step four: drying: after centrifugal separation of the suspension, the lower solid product is placed in an air oven for drying, and the drying temperature is 60°C. After sufficient drying for 1 h, the finished product of BiOI is obtained.

[0058] The scanning electron microscope image of BiOI obtained in this example 4 shows that the BiOI appears as dispersed microrods, Figure 9 As can be seen from Table 1, BiOI appears as dispersed microrods, but the amount of bismuth ions released by Bi2O3 microrods is less, and the number of BiOI nanoplates obtained is also less, but there is a significant increase in the amount of bismuth ions and the number of BiOI nanoplates compared to the amount of bismuth ions and the number of BiOI nanoplates in Example 2.

[0059] Example 5:

[0060] The synthesis method of BiOI proposed in Example 1 can be applied to other halogenated bismuth oxides, such as BiOCl. The experimental procedure is as follows:

[0061] Raw materials: potassium chloride (KCl) powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0062] The synthesis method of BiOCl includes the following steps:

[0063] Step one: prepare the pre-solution: weigh 8 g of potassium chloride solid powder, and configure the potassium chloride solid powder and 95% concentrated nitric acid into a KCl-HNO3 mixed solution with a concentration of 6 mM;

[0064] Step two: 0.5 g of bismuth oxide was added into 2 mL of KCl-HNO3 mixed solution with a concentration of 6 mM, and a suspension was obtained after sufficient reaction;

[0065] Step three: centrifugal stirring: the suspension was stirred on a magnetic stirrer for 10 min;

[0066] Step four: drying: after centrifugal separation of the suspension, the lower solid product was placed in an air oven for drying, the drying temperature was 60°C, and after sufficient drying for 1 h, the bismuth oxychloride product was obtained.

[0067] Example 6:

[0068] The synthesis method of bismuth oxyiodide proposed in Example 1 can also be applied to other halogenated bismuth oxides, such as bismuth oxybromide (BiOBr), and the experimental procedure is as follows:

[0069] Raw materials: potassium bromide (KBr) powder, concentrated nitric acid (HNO3) solution, bismuth oxide microrods;

[0070] The synthesis method of bismuth oxybromide includes the following steps:

[0071] Step one: prepare a pre-solution: weigh 10 g of potassium bromide solid powder, and configure the potassium bromide solid powder and 95% concentrated concentrated nitric acid into a KBr-HNO3 mixed solution with a concentration of 6 mM;

[0072] Step two: 0.5 g of bismuth oxide was added into 2 mL of KBr-HNO3 mixed solution with a concentration of 6 mM, and a suspension was obtained after sufficient reaction;

[0073] Step three: centrifugal stirring: the suspension was stirred on a magnetic stirrer for 10 min;

[0074] Step four: drying: after centrifugal separation of the suspension, the lower solid product was placed in an air oven for drying, the drying temperature was 60°C, and after sufficient drying for 1 h, the bismuth oxybromide product was obtained.

[0075] Example 7:

[0076] The BiOI microrods prepared in Example 1 can be used to spin BiOI thin films on glass or polymer carriers, including the following steps:

[0077] 1. Add 0.15 g of the obtained BiOI microrod product to 25 mL of a polyethylene glycol or block polymer (such as P123, F127) aqueous solution with a concentration of 5 mM;

[0078] 2. Put the clean glass slice into the BiOI suspension, and then put it into the oven, keeping the temperature above 60℃ for 20 minutes, and evaporate the surface solvent to obtain the BiOI microrod film;

[0079] 2-1. The suspension can also be dropped on the clean glass, and then put it into the spin coater to obtain the BiOI microrod film.

[0080] The thickness of the BiOI microrod film can be controlled by controlling the concentration of the BiOI microrod suspension, the spin coating speed, the glass slice immersion or the spin coating times.

[0081] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of synthesizing bismuthyl iodide, characterized by: The method comprises the following steps: Sp1: configure a pre-solution: weigh potassium iodide solid, and configure the potassium iodide solid and concentrated nitric acid into a KI-HNO3 mixed solution; The concentration of the KI-HNO3 mixed solution is 4-8 mM; Sp2: put bismuth oxide into an excessive amount of KI-HNO3 mixed solution, and fully react to obtain a suspension; The bismuth oxide is bismuth oxide microrods; Sp3: centrifugal stirring: the suspension is fully stirred on a magnetic stirrer for not less than 10 minutes; Sp4: drying: after centrifugal separation, the lower solid product is placed in an air oven for drying, and bismuth oxyiodide finished product is obtained.

2. The method of synthesizing bismuthyl iodide according to claim 1, characterized in that: The concentration of the KI-HNO3 mixed solution is 6 mM.

3. The method of synthesizing bismuthyl iodide of claim 1, wherein: The drying temperature of the lower solid product after centrifugal separation in the air oven is 40-80 DEG C.

4. The method of synthesizing bismuthyl iodide of claim 1, wherein: The drying time of the lower solid product is not less than 1 h.

5. The method of synthesizing bismuthyl iodide of claim 1, wherein: The bismuth oxyiodide finished product is stored in a sealed, light-proof reagent bottle.

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