Bi2O2Se micro-nano material as well as preparation method and application thereof

Abstract

The invention discloses a Bi2O2Se micro-nano material as well as a preparation method and application thereof, and belongs to the technical field of preparation of inorganic photoelectric micro-nano materials, and the ultrathin Bi2O2Se micro-nano material is mildly and conveniently prepared in an anion exchange manner. Compared with most existing Bi2O2Se preparation methods, the synthesis method has the advantages of low price, simplicity in operation, low energy consumption, good reproducibility and the like, the size, the thickness, the crystallinity, the atomic exposure rate, the defect state and the like of the Bi2O2Se micro-nano material can be effectively regulated and controlled by the synthesis method, and a reference is provided for rational design of a novel semiconductor photoelectric material; in addition, the obtained Bi2O2Se micro-nano material also has good photoelectric response performance, and is suitable for photoelectric response products.

Description

Technical Field

[0001] The present invention relates to the preparation technology of micro-nano materials, and particularly relates to a Bi2O2Se micro-nano material, a preparation method thereof and uses thereof, belonging to the technical field of the preparation of optoelectronic nano materials. Background Art

[0002] In 2004, Geim et al. first successfully exfoliated single-layer graphene from graphite using tape, creatively discovered planar two-dimensional materials, and opened a new era of two-dimensional material research. Since then, various new two-dimensional materials have been widely developed and studied. With their unique optical, electrical and mechanical properties, two-dimensional materials have been widely favored in the fields of energy, environment, printed electronics, flexible electronics, sensors, semiconductor manufacturing, medical treatment, etc. In recent years, due to its high carrier mobility, excellent stability, wide light absorption range, tunable energy band and excellent mechanical properties, the two-dimensional layered Bi2O2Se material has shown outstanding application potential and attractive development prospects in the fields of electronics and optoelectronics.

[0003] Therefore, various methods for the synthesis of Bi2O2Se materials are widely used, including chemical vapor deposition (CVD), chemical vapor transport (CVT), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), and molten salt method. However, the synthesis methods described in most literatures generally require harsh material synthesis conditions such as high temperature (800°C and above) and complex material preparation processes to achieve (Science Adv.2018,4,eaat8355; Adv.Mater.2019,31,1901964; Nature Electron.2020,3,473-478; Acc.Mater.Res.2021,2,842-853; ACS Nano 2021,15,8715-8723; Adv.Funct.Mater.2022,32,2201020; Sci.Adv.2022,8,eabq1781; PNAS2022,119,e2122436119), which seriously affects their wide application and is not in line with the green and low-carbon development concept. In addition, the prepared Bi2O2Se materials are generally concentrated on large-size micron materials and single crystal materials of 5μm and above, and only a few research reports involve Bi2O2Se nanomaterials (Nat. Nanotechnol. 2017, 12, 530-534; Nat. Commun. 2019, 10, 3331; Adv. Funct. Mater. 2021, 31, 2101170; Phys. Rev. B 2019, 100, 235307; Adv. Funct. Mater. 2021, 31, 2105795; Adv. Mater. 2021, 33, 2004786; Nat. Electron. 2022, 5, 643-649), and the preparation conditions are relatively harsh. Therefore, designing and developing a new method for synthesizing Bi2O2Se nanomaterials that is cheap, simple and high-yield has important research significance and great scientific value, and is also a technical problem that urgently needs to be solved in in-depth research in this field. Summary of the invention

[0004] In view of the problems in the prior art that the preparation conditions of the existing Bi2O2Se materials are harsh and the material thickness is large and the size is uneven, the present invention provides a Bi2O2Se micro-nano material and a preparation method and use thereof, and creates a batch of ultra-thin Bi2O2Se micro-nano materials by mildly and conveniently preparing them through anion exchange. The Bi2O2Se micro-nano material has significantly improved photogenerated electron-hole separation efficiency due to its atomically thin material thickness, thereby showing excellent photoelectric response performance.

[0005] To achieve the above technical objectives, the technical solutions adopted by the present invention are specifically described as follows:

[0006] According to the first embodiment of the present invention, a method for preparing a Bi2O2Se micro-nano material is provided:

[0007] A method for preparing a Bi2O2Se micro-nano material, the method comprising the following steps:

[0008] 1) Mix a bismuth salt solution with other soluble salt solutions to obtain a mixed solution, and then carry out a reflux reaction or a hydrothermal reaction on the mixed solution. After the reaction is completed, a Bi-O-based micro-nano precursor is obtained.

[0009] 2) Carry out an ion exchange reaction on the Bi-O-based micro-nano precursor and a selenium ion-containing solution. After the reaction is completed, the product is further subjected to heat treatment. After the heat treatment is completed, a Bi2O2Se micro-nano material is obtained.

[0010] Preferably, in step 1), the bismuth salt solution is one or more of a nitrate solution, a sulfate solution, and a chloride solution of metallic Bi, preferably one or more of a Bi(NO3)3·5H2O solution, a Bi2(SO4)3 solution, and a BiCl3 solution.

[0011] Preferably, in step 1), the concentration of the bismuth salt solution is 0.05 - 2.0 mol / L, preferably 0.1 - 1.5 mol / L, and more preferably 0.3 - 1.2 mol / L.

[0012] Preferably, in step 1), the other soluble salt solution is one or more of a halide solution of metallic lithium, a carbonate solution of metallic lithium, a sulfate solution of metallic lithium, a halide solution of metallic sodium, a carbonate solution of metallic sodium, a sulfate solution of metallic sodium, a halide solution of metallic potassium, a carbonate solution of metallic potassium, a sulfate solution of metallic potassium, and a cetyltrimethylammonium bromide solution. Preferably, it is one or more of a LiCl solution, a NaCl solution, a NaBr solution, a KBr solution, a KI solution, a K2CO3 solution, a K2SO4 solution, and a cetyltrimethylammonium bromide solution.

[0013] Preferably, in step 1), the concentration of the other soluble salt solution is 0.01 - 3.0 mol / L, preferably 0.05 - 2.5 mol / L, and more preferably 0.1 - 2.0 mol / L.

[0014] Preferably, in step 1), the solvents in the bismuth salt solution and the other soluble salt solution are each independently one or more of deionized water, ethanol, isopropanol, ethylene glycol, and tert-butanol. Preferably, the solvents in the bismuth salt solution and the other soluble salt solution are the same.

[0015] Preferably, in step 1), the amounts of bismuth salt solution and other soluble salt solutions added are such that the molar ratio of bismuth salt to other soluble salts in the mixed solution is 1:0.1-5, preferably 1:1-3.

[0016] Preferably, in step 2), the selenium ion solution is one or more of Na2Se solution, K2Se solution, Li2Se solution, sodium selenosulfate solution, and selenium powder solution (i.e., the selenium ion solution of the present invention is Se 2- ion solution), preferably one or more of Na2Se solution, K2Se solution, and Li2Se solution. Preferably, the solvent of the selenium ion solution is one or more of deoxygenated deionized water, deoxygenated ethanol, deoxygenated isopropanol, and hydrazine hydrate.

[0017] Preferably, in step 2), the concentration of the selenium ion solution is 0.001-8.0 mol / L, preferably 0.01-6 mol / L, more preferably 0.1-4 mol / L.

[0018] Preferably, in step 2), the amount of Bi-O-based micro-nano precursor and the selenium ion solution added is such that the molar ratio of bismuth to selenium is 1:1-5, preferably 1:2.2-3.5 (in the present invention, if Se 2- Too little selenium ion dosage will lead to incomplete conversion of Bi-O-based micro-nano precursors, and new impurity bismuth oxide will be introduced during subsequent heat treatment. Excessive selenium ions can completely convert Bi-O-based micro-nano precursors, but there will be a problem of excessive selenium content, which can be removed by heat treatment).

[0019] Preferably, in step 2), the obtained Bi2O2Se micro-nanomaterials include but are not limited to one or more of micro-nanosheets, micro-nanowires, micro-nanotubes, micro-nanorods, micro-nanoflowers, micro-nanobelts, micro-nanospheres and irregular micro-nanoparticles.

[0020] Preferably, step 1) is specifically as follows: taking a bismuth salt solution and other soluble salt solutions in proportion, then under stirring, adding the other soluble salt solutions dropwise into the bismuth salt solution, continuing to stir and mix evenly to obtain a mixed solution, and then adding the mixed solution into a reflux reactor for reflux reaction at 80-220°C (preferably 120-200°C, more preferably 140-180°C, and further preferably 150-170°C) for 3-24h (preferably 5-12h). After the reaction is completed, the reaction system is cooled and filtered, and the obtained product is washed with deionized water or anhydrous ethanol and centrifuged, and finally dried in a vacuum drying oven at 50-70°C (preferably 55-65°C) to obtain a Bi-O-based micro-nano precursor.

[0021] Preferably, step 2) is specifically as follows: Dissolve the Bi-O-based micro-nano precursor in deoxygenated deionized water (or ethanol or isopropanol) to obtain a precursor solution. Then, under vacuum or in an atmosphere protected by nitrogen or argon, add a selenium ion-containing solution to the precursor solution and mix evenly (for example, ultrasonic dispersion for 5 - 60 min), and react at 20 - 100 °C (preferably 40 - 80 °C, more preferably 50 - 80 °C, further preferably 60 - 80 °C) in an incubator for 4 - 24 h (preferably 6 - 14 h). After the reaction is completed, perform suction filtration and washing to obtain a crude product. Finally, place the crude product in a single-zone tube furnace and heat it to 100 - 700 °C (preferably 200 - 600 °C) under vacuum or in an atmosphere protected by nitrogen for thermal purification treatment for 1 - 48 h (preferably 2 - 36 h). After the heat treatment is completed, cool the product to room temperature to obtain the ultra-thin Bi2O2Se micro-nano material.

[0022] According to the second embodiment of the present invention, a Bi2O2Se micro-nano material is provided:

[0023] A Bi2O2Se micro-nano material obtained by the method described in the first embodiment.

[0024] Preferably, the thickness of the Bi2O2Se micro-nano material is less than 10 nm, preferably less than 8 nm, more preferably less than 5 nm.

[0025] According to the third embodiment of the present invention, a use of the Bi2O2Se micro-nano material is provided:

[0026] A use of the Bi2O2Se micro-nano material or a Bi2O2Se micro-nano material prepared by the method described in the first embodiment: Use the Bi2O2Se micro-nano material to prepare a photoelectric response film. Specifically: Uniformly disperse the Bi2O2Se micro-nano material powder in water or ethanol or isopropanol to obtain a dispersion, and then uniformly coat the dispersion on a conductive substrate by centrifugation or drop coating or spin coating to obtain a photoelectric response film.

[0027] Preferably, the conductive substrate is one or more of FTO, ITO, copper foam, nickel foam, etc.

[0028] Preferably, use the prepared photoelectric response film for one or more of photoelectric detection, photocatalysis, photoelectrocatalysis, photothermal catalysis, piezoelectric catalysis, and preparation of a light-responsive electrode, etc.

[0029] In the present invention, the selenium ion-containing solution contains Se 2-Solution of ions, preparation of selenium ion-containing solution: Weigh one or more of the following in one or more of the conditions such as in vacuum, high-purity nitrogen, high-purity argon, etc., such as Na2Se, K2Se, Li2Se, or Se powder (hydrazine hydrate solution of selenium powder. In the invention, hydrazine hydrate refers to 80% hydrazine hydrate. The hydrogen selenide generated by the reaction of selenium powder and hydrazine hydrate is soluble in water, that is, after the reaction, selenium exists in the form of selenium ions (Se 2- 2- )), etc., place them in a container, then add one or more of deoxygenated deionized water, ethanol, isopropanol, or hydrazine hydrate, etc. After the solid powder is completely dissolved, transfer all the obtained reaction solution to a volumetric flask and make up the volume to prepare a selenium ion-containing solution with a certain concentration. It should be noted that when using selenium powder as the selenium source, the solvent should be hydrazine hydrate to facilitate the obtaining of Seion solution.

[0030] In the present invention, the vacuum condition refers to a vacuum degree ≤ 10 -4 Pa. When protected by a nitrogen or argon atmosphere, the purity of nitrogen or argon ≥ 99.9%. In addition, it should be noted that in the present invention, all solvents used need to be deoxygenated to prevent the selenium anions from being oxidized and affecting the progress of the anion exchange reaction. In addition, the dosage of each solvent is not specifically limited, and its dosage only needs to enable the reaction to proceed normally (the solvent mainly plays a dispersing role to increase the contact area of the reactants), and its specific dosage can be reasonably adjusted according to the actual situation.

[0031] In the present invention, during the anion exchange reaction in step 2), the pH of the reaction system is 7 - 13. If the pH value is too high (> 14), the structure of the nano-precursor will be changed, resulting in the inability to obtain the target product; if the pH value is too low (< 7), too much selenium elemental impurity will be generated in the solution, resulting in the impurity of the target substance.

[0032] In the present invention, by calcination, part of the Se atoms volatilize to generate defect states, increasing its specific surface area of the microstructure, which is beneficial to improving its photocatalytic efficiency. This is because the band gap of Bi2O2Se is related to its thickness. Small size and thickness will widen the band gap of Bi2O2Se, optimizing its energy band structure. Therefore, in the field of photocatalysis, it is more conducive to the effective separation of photo-generated electrons and holes, thereby improving the photocatalytic efficiency.

[0033] In the present invention, the Bi-O-based micro-nano precursor includes one or more of bismuthyl carbonate (Bi2O2CO3) and bismuth oxychloride (BiOCl, BiOBr, or BiOI), etc.

[0034] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0035] 1: The present invention pioneeringly proposes a new method for synthesizing a class of ultra-thin Bi2O2Se micro-nano sheet materials, that is, preparing ultra-thin Bi2O2Se micro-nano sheet materials through an anion exchange method. This method has the advantages of low cost, simple operation, low energy consumption, good reproducibility, etc. compared with most existing preparation methods of Bi2O2Se materials. It can realize the rapid and batch preparation of Bi2O2Se micro-nano functional materials, and solves the problems of large energy consumption and complex synthesis process in the existing preparation methods of Bi2O2Se materials. At the same time, the synthesis method of the present invention can also effectively regulate the size, thickness, crystallinity, atomic exposure rate, defect state, etc. of Bi2O2Se micro-nano materials, providing a new method for scientifically designing and synthesizing new semiconductor optoelectronic materials.

[0036] 2: The Bi2O2Se micro-nano materials prepared by the present invention have good conductivity, high surface atomic exposure rate, rich defect states, adjustable microscopic electronic structure and energy band, etc., and can realize physicochemical properties that large-size micron materials and single crystals do not have. This Bi2O2Se micro-nano material can not only be used for photo / electric response electrodes, but also has the potential to shine in the fields of photoelectric detection, photocatalysis, photoelectrocatalysis, photothermal catalysis or piezoelectric catalysis, etc., providing new ideas and laying a foundation for solving the core scientific problems in the fields of energy, environment and chips. Brief Description of the Drawings

[0037] Figure 1 It is the TEM image of the Bi2O2Se nanosheets obtained in Example 1 of the present invention.

[0038] Figure 2 It is the XRD pattern of the Bi2O2Se nanosheets obtained in Example 1 of the present invention.

[0039] Figure 3 It is the AFM image (a) and its thickness images (b, c) of the Bi2O2Se nanosheets obtained in Example 1 of the present invention.

[0040] Figure 4 It is the ultraviolet-visible absorption spectrum of the Bi2O2Se micro-nanosheets obtained in Example 1 of the present invention.

[0041] Figure 5 It is the photocurrent response curve of the Bi2O2Se micro-nanosheets obtained in Example 1 of the present invention.

[0042] Figure 6 It is the XRD pattern of the Bi2O2Se nanosheets obtained in Example 2 of the present invention.

[0043] Figure 7 It is the AFM image (a) and its thickness image (b) of the Bi2O2Se nanosheets obtained in Example 2 of the present invention.

[0044] Figure 8 This is the XRD pattern of the Bi2O2Se nanosheets obtained in Example 3 of the present invention.

[0045] Figure 9 This is the XRD pattern of the Bi2O2Se nanosheets obtained in Example 4 of the present invention. Detailed implementation manners

[0046] The technical solutions of the present invention will be illustrated by way of examples below. The scope of protection claimed by the present invention includes but is not limited to the following examples.

[0047] Example 1

[0048] First, weigh 1.160 g of Bi(NO3)3·5H2O and 0.4 g of KI and dissolve them in 20 ml of ethylene glycol respectively to prepare solutions, which are denoted as solution A and solution B respectively; then, under continuous stirring, slowly add solution B dropwise to solution A until the solution changes from clear to orange-yellow to obtain a mixed solution, denoted as solution C. Then transfer the obtained mixed solution C to a high-pressure reaction kettle, seal it, and place it in a constant-temperature drying oven. Slowly heat it to 160 °C at a heating rate of 10 °C / min and react at this temperature for 12 h. After the reaction is completed and cooled, wash the obtained mixture with deionized water and centrifuge it 3 times. Place the washed precipitate in a vacuum drying oven at 60 °C and dry it overnight to obtain orange-red BiOI solid.

[0049] Weigh 0.035 g of BiOI powder and add it to a reaction flask containing 20 mL of deoxygenated deionized water for ultrasonic dispersion and vacuum pumping to obtain a precursor solution; weigh 0.125 g of sodium selenide powder and add 25 ml of deoxygenated deionized water to it to prepare a selenium ion-containing solution; then add 8 mL of the prepared selenium ion-containing solution to the precursor solution, perform ultrasonic treatment for 5 min, and place the obtained mixture solution in a vacuum oven at 80 °C for reaction for 12 h. After the reaction is cooled, obtain a black-red Bi2O2Se crude product.

[0050] Place the Bi2O2Se crude product in a single-temperature zone tube furnace, use N2 as the protective gas, heat it to 500 °C at a heating rate of 10 °C / min, react at this temperature for 3 h, and then cool it to room temperature to obtain pure-phase Bi2O2Se micro-nanosheets.

[0051] The phase, morphology, light absorption properties, and transient photocurrent performance of the Bi2O2Se micro-nanosheets obtained in this example are as Figures 1-5 shown: Figure 1 The transmission electron microscope results in show that the synthesized Bi2O2Se material is composed of curly and cross-linked micro-nanosheets. The lateral size of the micro-nanosheets is between 0.1 - 2 μm, and the thickness is about 2.50 nm.Figure 2 The XRD results in indicate that the synthesized Bi2O2Se micro-nanosheets have a relatively pure phase, and its characteristic diffraction peaks are in good agreement with the standard card number (JCPDS No.73-1316) of Bi2O2Se. Figure 3 The thickness map of AFM in shows that the thickness of the synthesized Bi2O2Se micro-nanosheets is approximately 2.50 nm. Figure 4 It shows that the absorption cut-off edge of the prepared Bi2O2Se micro-nanosheets can reach the near-infrared region. Figure 5 It indicates that the prepared Bi2O2Se micro-nanosheets have good photocurrent response properties.

[0052] Example 2

[0053] First, weigh 1.160 g of Bi(NO3)3·5H2O and 0.4 g of KI and dissolve them in 20 ml of ethylene glycol respectively to prepare solutions, which are denoted as solution A and solution B respectively; then, under continuous stirring, add solution B dropwise to solution A until the solution changes from clear to orange-yellow to obtain a mixed solution, denoted as solution C. Then transfer the obtained mixed solution C to a high-pressure reaction kettle, seal it, and place it in a constant-temperature drying oven. Slowly heat it to 160 °C at a heating rate of 10 °C / min and react at this temperature for 12 h. After the reaction is completed and cooled, wash the obtained mixture with deionized water and centrifuge it 3 times. Place the washed precipitate in a 60 °C vacuum drying oven and dry it overnight to obtain orange-red BiOI solid.

[0054] Weigh 0.025 g of BiOI powder and add it to a reaction flask containing 20 mL of deoxygenated deionized water, and perform ultrasonic dispersion and vacuum pumping treatment to obtain a precursor solution; weigh 0.125 g of sodium selenide powder and add 25 ml of deoxygenated deionized water to it to prepare a selenium ion-containing solution; then add 6 mL of the prepared selenium ion-containing solution to the precursor solution, perform ultrasonic treatment for 8 min, and place the obtained mixed solution in a vacuum oven at 80 °C for reaction for 12 h. After the reaction is cooled, obtain a black-red Bi2O2Se crude product.

[0055] Place the Bi2O2Se crude product in a single-temperature zone tube furnace, use N2 as the protective gas, heat it to 520 °C at a heating rate of 5 °C / min, react at this temperature for 3 h, and then cool it to room temperature to obtain pure-phase Bi2O2Se micro-nanosheets (with an average of about 2.40 nm).

[0056] The phase of the Bi2O2Se micro-nanosheets prepared in this example, as Figure 6As shown, it can be seen from the figure that the Bi2O2Se micro-nanosheets also have a relatively pure phase, and the target diffraction peaks also match well with the standard card number of Bi2O2Se (JCPDS No. 73-1316).

[0057] Example 3

[0058] First, weigh 0.484 g of Bi(NO3)3·5H2O and place it in a 250 mL beaker. Then add 140 mL of deionized water and stir magnetically at 60 °C in a water bath until the solid powder is completely dissolved. Then, adjust its pH to 10.0 with 1.0 mol / L NaOH solution. After that, add 0.011 g of Na2CO3 powder to the solution under vigorous stirring. After stirring for 1 min, place the beaker containing the mixture in a constant temperature drying oven and react at 80 °C for 12 h. After the reaction is completed, wash it 3 times with ionized water and dry it overnight to obtain Bi2O2CO3 powder.

[0059] Weigh 0.040 g of Bi2O2CO3 powder and add it to a reaction flask containing 20 mL of deoxygenated deionized water, and perform ultrasonic dispersion and vacuum pumping to obtain a precursor solution. Weigh 100 mg of Se powder and place it in a clean 25 ml beaker. Then add 10 ml of hydrazine hydrate to the beaker and stir magnetically for 4 h to obtain a selenium ion-containing solution. Then add 3 mL of the prepared selenium ion-containing solution to the precursor solution and stir magnetically for 1.5 h. Then place the obtained mixture solution in a 60 °C vacuum box and react for 12 h. After the reaction cools down, a black-red Bi2O2Se crude product is obtained.

[0060] Place the Bi2O2Se crude product in a single-temperature zone tube furnace, use N2 as the protective gas, and heat it at a heating rate of 10 °C / min to 540 °C and react for 3 h, then cool it to room temperature to obtain pure-phase Bi2O2Se micro-nanosheets (average thickness is about 2.92 nm).

[0061] The phase of the Bi2O2Se micro-nanosheets prepared in this example, as Figure 7 shown, it can be found from the figure that the micro-nanosheets also present a pure Bi2O2Se phase, and the material diffraction peaks are also consistent with the standard card number of Bi2O2Se (JCPDS No. 73-1316).

[0062] Example 4

[0063] First, weigh 0.500 g of Bi(NO3)3·5H2O and place it in the inner liner of a 10 mL autoclave. Then, add 0.5 g of cetyltrimethylammonium bromide to it. After that, add 25 mL of deionized water. Stir magnetically for 1 h, then place it in an oven and react at 160 °C for 18 h. After the reaction is completed, filter the resulting mixture by suction, and wash it twice with deionized water and ethanol respectively. Place the obtained wet powder in a vacuum drying oven at 60 °C and dry it overnight to obtain BiOBr powder.

[0064] Weigh 0.030 g of BiOBr powder and disperse it in 20 mL of deoxygenated deionized water. Place it in a 40 mL sealed reaction flask for deoxygenation treatment to obtain a precursor solution; weigh 200 mg of Se powder and place it in a 50 ml clean beaker. Then, add 20 mL of hydrazine hydrate to the beaker and stir magnetically for 4 h to obtain a selenium ion-containing solution; then add 3 mL of the selenium ion-containing solution to the precursor solution, stir magnetically for 1 h, place it in a vacuum drying oven and react at 75 °C for 12 h. Filter and wash the resulting mixture, and dry the collected solid to obtain a crude Bi2O2Se product. Further, place the above-mentioned crude Bi2O2Se product in a single-zone tube furnace, use N2 as the protective gas, and heat it at a heating rate of 10 °C / min to 500 °C, and perform thermal purification treatment at this temperature for 3 h to obtain pure-phase Bi2O2Se micro-nanosheets (average thickness is about 2.97 nm).

[0065] Perform a phase test on the obtained Bi2O2Se micro-nano material, and the results are as Figure 8 shown. The experimental results show that the phase of the Bi2O2Se micro-nanosheets synthesized in this example is in good agreement with the standard card of Bi2O2Se (card number: JCPDS No. 73-1316).

[0066] Example 5

[0067] Repeat Example 1, except that sodium selenide is replaced with an equimolar amount of potassium selenide.

[0068] Example 6

[0069] Repeat Example 1, except that sodium selenide is replaced with an equimolar amount of lithium selenide.

[0070] Example 7

[0071] Repeat Example 1, except that sodium selenide is replaced with an equimolar amount of sodium thiosulfate.

[0072] Example 8

[0073] Repeat Example 1, except that potassium iodide is replaced with an equimolar amount of potassium chloride.

[0074] Example 9

[0075] Example 1 was repeated, except that the amount of sodium selenide powder used was 0.0270 g.

[0076] Example 10

[0077] Example 1 was repeated, except that the amount of sodium selenide powder used was 0.0145 g.

[0078] Comparative Example 1

[0079] First, 1.160 g of Bi(NO3)3·5H2O and 0.4 g of KI were weighed and dissolved in 20 ml of ethylene glycol respectively to prepare solutions, which were denoted as Solution A and Solution B respectively; then, under continuous stirring, Solution B was added dropwise to Solution A until the solution changed from clear to orange-yellow, obtaining a mixed solution, denoted as Solution C. Then the obtained mixed solution C was transferred to a high-pressure reactor, sealed, and placed in a constant-temperature drying oven. It was slowly heated to 160 °C at a heating rate of 10 °C / min and reacted at this temperature for 12 h. After the reaction was completed and cooled, the obtained mixture was washed with deionized water and centrifuged 3 times. The washed precipitate was placed in a vacuum drying oven at 60 °C and dried overnight to obtain orange-red BiOI solid.

[0080] 0.035 g of BiOI powder was weighed and added to a reaction flask containing 20 mL of deoxygenated deionized water for ultrasonic dispersion and vacuum pumping treatment to obtain a precursor solution; 0.189 g of sodium selenate powder was weighed and 25 ml of deoxygenated deionized water was added to it to prepare a selenium ion-containing solution; then 8 mL of the prepared selenium ion-containing solution was added to the precursor solution, and ultrasonic treatment was carried out for 5 min. The obtained mixture solution was placed in a vacuum oven at 70 °C and reacted for 12 h. After the reaction was cooled, the product was obtained, and it was detected that no Bi2O2Se was generated in the product system.

[0081] Comparative Example 2

[0082] Comparative Example 1 was repeated, except that an equimolar amount of selenium powder was used to replace sodium selenate powder. After the reaction was completed, it was detected that no Bi2O2Se was generated in the reaction system.

[0083] Comparative Example 3

[0084] Comparative Example 1 was repeated, except that a mixture of equimolar amounts of selenium powder and sodium sulfite was used to replace sodium selenate powder. After the reaction was completed, it was detected that only a very small amount of Bi2O2Se was generated in the reaction system, and there were many impurities.

[0085] Comparative Example 4

[0086] Weigh 1.16 g of Bi(NO3)3·5H2O and 0.4 g of KI respectively, dissolve them in 20 ml of ethylene glycol to prepare solutions, which are respectively recorded as solution A and solution B; weigh 0.1249 g of sodium selenide powder, add 25 ml of deoxygenated deionized water to it to prepare a selenium ion-containing solution; then take 8 mL of the prepared selenium ion-containing solution and mix it with solution A and solution B, perform ultrasonic treatment for 5 min, place the obtained mixture solution in a vacuum oven at 60 °C for reaction for 12 h. After the reaction cools down, it is detected that a small amount of Bi2O2Se is generated in the reaction system and there are many impurities.

[0087] Application Example

[0088] Weigh the products obtained in each example and comparative example (10 mg each) and place them in different centrifuge tubes respectively, and add 3 ml of ethanol to each for ultrasonic dispersion treatment; then, cut 1 cm × 2 cm of FTO glass, put them into the above-mentioned respective dispersions, and coat the Bi2O2Se micro-nano powder on the conductive substrate by centrifugation to prepare a photoelectric response film. Finally, using the Bi2O2Se photoelectrode film as the working electrode, a Pt sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode, with an aqueous solution of 0.1 mol / L sodium sulfate as the electrolyte, the photoelectric response performance is tested at 0.252 V (vs. Ag / AgCl).

[0089] Comparison table of test results of photoelectric response performance:

[0090]

Claims

1. A preparation method of Bi2O2Se micro-nano materials, characterized in that: The method includes the following steps: 1) Mix a bismuth salt solution with other soluble salt solutions to obtain a mixed solution, and then carry out a reflux reaction or a hydrothermal reaction on the mixed solution. After the reaction is completed, a Bi-O-based micro-nano precursor is obtained; 2) Carry out an ion exchange reaction between the Bi-O-based micro-nano precursor and a selenium ion-containing solution. After the reaction is completed, heat-treat the product. After the heat treatment is completed, a Bi2O2Se micro-nano material is obtained.

2. The method according to claim 1, wherein: In step 1), the bismuth salt solution is one or more of a nitrate solution, a sulfate solution, and a chloride solution of metallic Bi, preferably one or more of a Bi(NO3)3·5H2O solution, a Bi2(SO4)3 solution, and a BiCl3 solution; Preferably, the concentration of the bismuth salt solution is 0.05 - 2.0 mol / L, preferably 0.1 - 1.5 mol / L, and more preferably 0.3 - 1.2 mol / L.

3. The method according to claim 1 or 2, characterized in that: The other soluble salt solutions are one or more of a halide solution of metallic lithium, a carbonate solution of metallic lithium, a sulfate solution of metallic lithium, a halide solution of metallic sodium, a carbonate solution of metallic sodium, a sulfate solution of metallic sodium, a halide solution of metallic potassium, a carbonate solution of metallic potassium, a sulfate solution of metallic potassium, and a cetyltrimethylammonium bromide solution; preferably one or more of a LiCl solution, a NaCl solution, a NaBr solution, a KBr solution, a KI solution, a K2CO3 solution, a K2SO4 solution, and a cetyltrimethylammonium bromide solution; Preferably, the concentration of the other soluble salt solutions is 0.01 - 3.0 mol / L, preferably 0.05 - 2.5 mol / L, and more preferably 0.1 - 2.0 mol / L.

4. The method according to any one of claims 1 to 3, characterized in that: In step 1), the solvents in the bismuth salt solution and the other soluble salt solutions are each independently one or more of deionized water, ethanol, isopropanol, ethylene glycol, and tert-butanol; preferably, the solvents in the bismuth salt solution and the other soluble salt solutions are the same; Preferably, in step 1), the addition amounts of the bismuth salt solution and the other soluble salt solutions are such that the molar ratio of the bismuth salt to the other soluble salt in the mixed solution is 1:0.1 - 5, preferably 1:1 - 3.

5. The method according to any one of claims 1 to 4, characterized in that: In step 2), the selenium ion-containing solution is one or more of a Na2Se solution, a K2Se solution, a Li2Se solution, a sodium selenosulfate solution, and a selenium powder solution, preferably one or more of a Na2Se solution, a K2Se solution, and a Li2Se solution; preferably, the solvent of the selenium ion-containing solution is one of deoxygenated deionized water, deoxygenated ethanol, deoxygenated isopropanol, and hydrazine hydrate; Preferably, the concentration of the selenium ion-containing solution is 0.001 - 8.0 mol / L, preferably 0.01 - 6 mol / L, and more preferably 0.1 - 4 mol / L.

6. The method according to any one of claims 1-5, characterized in that: In step 2), the addition amounts of the Bi-O-based micro-nano precursor and the selenium ion-containing solution are such that the molar ratio of bismuth to selenium is 1:1 - 5, preferably 1:2.2 - 3.5; The Bi2O2Se micro-nano materials include, but are not limited to, one or more of micro-nano sheets, micro-nano wires, micro-nano tubes, micro-nano rods, micro-nano flowers, micro-nano belts, micro-nano spheres, and irregular micro-nano particles, etc.

7. The method according to any one of claims 1 to 6, characterized in that: Step 1) Specifically: Measure bismuth salt solution and other soluble salt solutions according to the proportional amounts. Then, under continuous stirring, add the other soluble salt solution dropwise to the bismuth salt solution. After continuing to stir and mix evenly to obtain a mixed solution, then add the mixed solution to a reflux reactor or a hydrothermal reaction kettle and reflux at a temperature of 80 - 220 °C (preferably 120 - 200 °C) for 3 - 24 h (preferably 5 - 12 h). After the reaction is completed, cool the reaction system and filter. Wash and centrifuge the filter cake with deionized water or absolute ethanol. Finally, dry it in a vacuum drying oven at 50 - 80 °C (preferably 55 - 65 °C) to obtain a Bi-O-based micro-nano precursor.

8. The method according to claim 7, wherein: Step 2) Specifically: Dissolve the Bi-O-based micro-nano precursor in deoxygenated deionized water (or ethanol or isopropanol) to obtain a precursor solution. Then, under vacuum or in an atmosphere protected by nitrogen or argon, add a selenium ion-containing solution to the precursor solution and mix evenly (for example, ultrasonic dispersion for 5 - 60 min), and react at 20 - 100 °C (preferably 40 - 80 °C) in an incubator for 4 - 24 h (preferably 6 - 14 h). After the reaction is completed, perform suction filtration and washing to obtain a crude product. Finally, place the crude product in a single-zone tube furnace and heat-purify it at 100 - 700 °C (preferably 200 - 600 °C) under vacuum or in an atmosphere protected by nitrogen for 1 - 48 h (preferably 2 - 36 h). After the heat treatment is completed, cool the product to room temperature to obtain the Bi2O2Se micro-nano materials.

9. A Bi2O2Se micro-nano material, characterized in that: The Bi2O2Se micro-nano materials are prepared by the method described in any one of claims 1 - 8; Preferably, the thickness of the Bi2O2Se micro-nano materials is less than 10 nm, preferably less than 8 nm, and more preferably less than 5 nm.

10. Use of a Bi2O2Se micro-nano material or use of a Bi2O2Se micro-nano material prepared by the method according to any one of claims 1-8 or use of the Bi2O2Se micro-nano material according to claim 9, characterized in that: Use the Bi2O2Se micro-nano materials to prepare a photoelectric response thin film; specifically: Uniformly disperse the Bi2O2Se micro-nano material powder in water or ethanol or isopropanol to obtain a dispersion liquid, and then uniformly coat the dispersion liquid on a conductive substrate by centrifugation or drop coating or spin coating to obtain a photoelectric response thin film; Preferably, the conductive substrate is one or more of FTO, ITO, copper foam, and nickel foam; Preferably, use the prepared photoelectric response thin film for one or more of photoelectric detection, photocatalysis, photoelectrocatalysis, photothermal catalysis, piezoelectric catalysis, and the preparation of a light-responsive electrode.

Images