A method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction at a self-template heterophase interface

Abstract

The application provides a method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction of self-template heterogeneous interface, wherein NaBiO3.2H2O and C3N3(NH2)3 are added into a hydrothermal reactor containing distilled water, and stirred uniformly to obtain a solid-liquid mixture; the solid-liquid mixture is subjected to in-situ redox reaction of self-template heterogeneous interface under hydrothermal conditions to prepare Bi2O2CO3 nanosheets; wherein NaBiO3.2H2O is used as a bismuth source, and also as an oxidant and a solid template agent. The application adopts the in-situ redox reaction of self-template heterogeneous interface preparation technology, which can reduce the agglomeration of product particles, and the preparation process is simple and easy to control; meanwhile, NaBiO3.2H2O is not only a bismuth source, but also an oxidant and a solid template agent, so that the application does not need to add additional redox agents and template agents, improves the purity of the product, and meets the requirements of green synthesis of materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanomaterials and their preparation, and in particular to a method for preparing Bi2O2CO3 nanosheets through in-situ redox reaction at the interface of self-templates. BACKGROUND

[0002] Bismuth subcarbonate (Bi2O2CO3), also known as bismuth subcarbonate, has important applications in the fields of medicine, environmental protection, materials, etc. due to its unique layered structure, chemical stability and multifunctionality.

[0003] At present, bismuth subcarbonate has been widely used as an astringent in the pharmaceutical industry, an X-ray diagnostic sunscreen, and can be used for the treatment of gastritis, bacterial dysentery, diarrhea, enteritis, etc. In addition, bismuth subcarbonate can be used to manufacture bismuth salts, enamel solubilizers, pearlescent plastic additives, etc. Moreover, as one of the representative bismuth compound semiconductors with Aurivillius-type oxide structure, bismuth subcarbonate has a typical "sillén" structure, i.e. (Bi2O2) 2+ atomic layer, (CO3) 2- atomic layers are arranged alternately in a layered structure. Among them, (Bi2O2) 2+ atomic layer and (CO3) 2- atomic layers have a strong built-in electric field, which can effectively promote the transfer and separation of photo-generated electron-hole pairs and exhibit excellent photocatalytic performance. Existing studies have shown that when applied to wastewater treatment, bismuth subcarbonate can efficiently photocatalyze the degradation of organic pollutants (such as rhodamine B and methylene blue) in water, and is a potential excellent photocatalytic material.

[0004] However, the current preparation method of bismuth subcarbonate mainly uses trivalent bismuth salt as raw material and prepares bismuth subcarbonate through homogeneous solution method. Although this method can prepare bismuth subcarbonate, the product particles are prone to agglomeration due to the homogeneous solution reaction, and it is usually difficult to control to obtain the target product with less aggregation and uniform particle size distribution.

[0005] Therefore, it is necessary to develop a new preparation method of bismuth subcarbonate (Bi2O2CO3). SUMMARY

[0006] The technical problem to be solved by the present application is to provide a method for preparing Bi2O2CO3 nanosheets through in-situ redox reaction at the interface of self-templates, which can reduce the agglomeration of product particles and has a simple preparation process and is easy to control.

[0007] The present application solves the above technical problems by adopting the following technical solutions:

[0008] A method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction of self-template heterogeneous interface, water-insoluble NaBiO3.2H2O (sodium bismuthate dihydrate) and water-soluble C3N3(NH2)3 (melamine) are added into a hydrothermal reactor containing distilled water, and stirred uniformly to obtain a solid-liquid mixture; the solid-liquid mixture is prepared into Bi2O2CO3 nanosheets by in-situ redox reaction of self-template heterogeneous interface under hydrothermal conditions; in the above reaction, NaBiO3.2H2O is used as a bismuth source, and at the same time, the NaBiO3.2H2O also acts as an oxidizing agent and a solid template agent, and the reaction process is as follows:

[0009]

[0010] As one of the preferred modes of the present application, the molar ratio of NaBiO3.2H2O to C3N3(NH2)3 is 1:1.

[0011] As one of the preferred modes of the present application, the solid-liquid mixture is reacted under hydrothermal conditions at 180-200°C for 10-30h.

[0012] As one of the preferred modes of the present application, after the hydrothermal reaction, the reaction product is obtained by centrifugal separation, distilled water washing and vacuum drying to obtain the target Bi2O2CO3 nanosheets.

[0013] As one of the preferred modes of the present application, the vacuum drying conditions are 60°C, 0.1Mpa vacuum degree, and vacuum drying for 2h.

[0014] As one of the preferred modes of the present application, the thickness of the Bi2O2CO3 nanosheets is 10-15nm.

[0015] As one of the preferred modes of the present application, in the Bi2O2CO3 nanosheets, the average grain size of Bi2O2CO3 is 73.1-93.7nm.

[0016] Reaction principle:

[0017] Since sodium bismuthate dihydrate is a poorly soluble solid substance, the heterogeneous redox reaction of sodium bismuthate dihydrate and melamine solution occurs on the surface of the sodium bismuthate dihydrate solid; in the reaction, the sodium bismuthate dihydrate is reduced to trivalent bismuth salt by the melamine; at the same time, the melamine is oxidized by the sodium bismuthate and generates carbonate ions, and the trivalent bismuth salt and the carbonate ions are immediately converted into bismuth carbonate in-situ, and deposited on the surface of the sodium bismuthate dihydrate solid template; in the above reaction process, the sodium bismuthate dihydrate is both an oxidizing agent and a sacrificial template agent, and as the redox reaction between the sodium bismuthate dihydrate and the melamine continues, the sodium bismuthate dihydrate is finally completely converted into bismuth carbonate in-situ, and bismuth carbonate nanosheets are prepared.

[0018] The present application has the following advantages over the prior art:

[0019] (1) The present application uses a self-template heterogeneous interface in-situ redox reaction preparation technology, which can reduce the agglomeration of product particles (solid surface in-situ conversion deposition can inhibit the migration of product particles and reduce agglomeration), and the preparation process is simple and easy to control;

[0020] (2) In the preparation of the present application, sodium bismuthate dihydrate (NaBiO3·2H2O) not only provides bismuth source for the reaction, but also acts as an oxidizing agent and a solid template, so that the present application does not need to add additional redox agents and templates, thereby improving the purity of the product and meeting the requirements of green synthesis of materials;

[0021] (3) In the preparation method of the present application, the raw materials are cheap and easy to obtain, the process is simple, the operation is reliable, and the industrial production is easy. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a scanning electron microscope image of the product of Example 2 of the present application;

[0023] Figure 2 is an XRD pattern of the product of each embodiment of the present application (with reference to the XRD of bismuthyl carbonate). DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below, and the present embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments. Meanwhile, the reagents and experimental methods used in the following embodiments and experimental examples are conventional reagents or methods in the art, which are not described in detail.

[0025] Example 1

[0026] A method for preparing Bi2O2CO3 nanosheets by self-template heterogeneous interface in-situ redox reaction in the present embodiment:

[0027] 0.01 mol of NaBiO3·2H2O (sodium bismuthate dihydrate) and 0.01 mol of C3N3(NH2)3 (melamine) were weighed according to a molar ratio of 1:1 and added into a 50 ml hydrothermal reactor containing 40 ml distilled water, and stirred uniformly to obtain a solid-liquid mixture. Subsequently, the solid-liquid mixture was sealed and reacted under hydrothermal conditions at 180℃ for 10 h, and Bi2O2CO3 was generated through self-template heterogeneous interface in-situ redox reaction; the reaction product was separated by centrifugation, washed with distilled water, and vacuum dried at 60℃ and a vacuum degree of 0.1 Mpa for 2 h to obtain Bi2O2CO3 nanosheets.

[0028] In the above-mentioned "self-templated heterogeneous interface in situ redox reaction", NaBiO3·2H2O is used as the bismuth source. At the same time, NaBiO3·2H2O also serves as the oxidant and solid template. The reaction process is as follows:

[0029]

[0030] Example 2

[0031] The method of preparing Bi2O2CO3 nanosheets by in-situ redox reaction at a self-templated heterogeneous interface in this embodiment is basically the same as that in Example 1, with the main difference being that the solid-liquid mixture is reacted under hydrothermal conditions at 190°C for 10 hours.

[0032] Example 3

[0033] The method of preparing Bi2O2CO3 nanosheets by in-situ redox reaction at a self-templated heterogeneous interface in this embodiment is basically the same as that in Example 1, with the main difference being that the solid-liquid mixture is reacted under hydrothermal conditions at 190°C for 20 hours.

[0034] Example 4

[0035] The method of preparing Bi2O2CO3 nanosheets by in-situ redox reaction at a template heterogeneous interface in this embodiment is basically the same as that in Example 1, with the main difference being that the solid-liquid mixture is reacted under hydrothermal conditions at 190°C for 30 hours.

[0036] Example 5

[0037] The method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction at a self-templated heterogeneous interface in this embodiment is basically the same as that in Example 1, with the main difference being that the solid-liquid mixture is reacted under hydrothermal conditions at 200°C for 10 hours.

[0038] Experimental Example 1

[0039] The product obtained in the above embodiment (taking embodiment 2 as an example) was observed under a scanning electron microscope (SEM), and the results were as follows: Figure 1 shown.

[0040] from Figure 1 It can be seen that the obtained product is in the form of nanosheets, and the thickness of the nanosheets is about 10 to 15 nm.

[0041] Experimental Example 2

[0042] The product obtained in the above embodiment was subjected to X-ray diffraction analysis (XRD analysis), and the results were as follows: Figure 2 shown.

[0043] Figure 2The XRD pattern of the product prepared in each embodiment of the present application is prepared with bismuthyl carbonate (PDF #04-009-8533) as a reference. From Figure 2 It can be seen that in the XRD pattern of the product of each embodiment of the present application, only the characteristic diffraction peak of bismuthyl carbonate (Bi2O2CO3) exists, and no diffraction peak of other phases exists, indicating that after a certain time of hydrothermal reaction, sodium bismuthate (NaBiO3) is reduced and converted into bismuthyl carbonate (Bi2O2CO3) by melamine (C3N3(NH2)3).

[0044] At the same time, according to the XRD analysis of the product of the above embodiment, the average grain size of bismuthyl carbonate (Bi2O2CO3) in the product of each embodiment is obtained by calculation using the Scherrer formula, as shown in Table 1.

[0045] Table 1 Average grain size of bismuthyl carbonate in the product of each embodiment

[0046]

[0047]

[0048] Analysis of the above results:

[0049] (1) When NaBiO3·2H2O and C3N3(NH2)3 are added to distilled water in a molar ratio of 1:1 and hydrothermally reacted at 190°C for 10h, 20h and 30h respectively, the average grain size of Bi2O2CO3 in the obtained product is 81.3nm, 85.2nm and 88.1nm respectively; indicating that as the hydrothermal reaction time increases, the average grain size of Bi2O2CO3 gradually increases.

[0050] (2) When NaBiO3·2H2O and C3N3(NH2)3 are added to distilled water in a molar ratio of 1:1 and hydrothermally reacted at 180°C, 190°C and 200°C for 10h respectively, the average grain size of Bi2O2CO3 in the obtained product is 73.1nm, 81.3nm and 93.7nm respectively; indicating that as the hydrothermal reaction temperature increases, the average grain size of Bi2O2CO3 increases.

[0051] Accordingly, in the preparation process, the average grain size of the components in the product can be controlled by appropriately controlling the hydrothermal reaction temperature and reaction time.

[0052] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing Bi2O2CO3 nanosheets via in-situ redox reaction at a template heterogeneous interface, characterized in that: NaBiO3·2H2O and C3N3(NH2)3 are added to a hydrothermal reactor containing distilled water, wherein the molar ratio of NaBiO3·2H2O to C3N3(NH2)3 is 1:1, and the mixture is stirred uniformly to obtain a solid-liquid mixture; the solid-liquid mixture is reacted under hydrothermal conditions of 180-200°C for 10-30h, and Bi2O2CO3 nanosheets are prepared through an in situ redox reaction at the heterogeneous interface of the self-template. In the above reaction, NaBiO3·2H2O is used as a bismuth source, and the NaBiO3·2H2O also serves as an oxidant and a solid template. The reaction process is as follows: ； In the Bi2O2CO3 nanosheets, the average grain size of Bi2O2CO3 is 73.1-93.7 nm.

2. The method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction from a template heterogeneous interface according to claim 1, characterized in that: After the hydrothermal reaction, the reaction product is centrifuged, washed with distilled water and vacuum dried to obtain the target Bi2O2CO3 nanosheets.

3. The method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction from a template heterogeneous interface according to claim 2, characterized in that: The vacuum drying conditions are: 60° C., 0.1 MPa vacuum degree, and vacuum drying for 2 h.

4. The method for preparing Bi2O2CO3 nanosheets by in-situ redox reaction from a template heterogeneous interface according to any one of claims 1 to 3, characterized in that: The thickness of the Bi2O2CO3 nanosheet is 10-15 nm.

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