Method for preparing TiO2-Bi2O (OH) 2SO4 nano-composite through synergistic reaction

Abstract

The invention relates to the technical field of photocatalysis, and provides a method for preparing a TiO2-Bi2O (OH) 2SO4 nano-composite through synergistic reaction, which comprises the following steps: adding sodium bismuthate dihydrate, sodium sulfite and titanium sulfate into a hydrothermal reaction kettle containing distilled water to obtain a solid-liquid mixture; and preparing the TiO2-Bi2O (OH) 2SO4 nano-composite from the solid-liquid mixture under a hydrothermal condition through a synergistic effect of a hydrolysis crystallization reaction of titanium sulfate and a heterogeneous interface in-situ oxidation-reduction reaction of sodium bismuthate dihydrate. The preparation method has the advantages that the TiO2-Bi2O (OH) 2SO4 nano-composite is prepared on the basis of a synthetic strategy of a synergistic effect of a hydrolysis crystallization reaction and a heterogeneous interface in-situ oxidation-reduction reaction, the preparation steps are simple, the operation is convenient, and the compounding effect between TiO2 and Bi2O (OH) 2SO4 is good.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysis, and in particular to a method for preparing a TiO 2 -Bi 2 O(OH) 2 SO 4 nano-composite by a synergistic reaction. Background Art

[0002] Since the discovery of the hydrogen production performance of titanium dioxide semiconductor by photocatalytic water splitting in 1972, semiconductor photocatalysis technology has attracted much attention and emphasis from the academic and industrial circles.

[0003] However, when a single pure titanium dioxide photocatalytic material is used, photo-generated electrons and holes are easily recombined, resulting in a decrease in the photo-quantum efficiency. Therefore, preventing the recombination of photo-generated electrons and holes and improving the photocatalytic efficiency have become one of the major challenges in the field of photocatalysis research. At the same time, in the practical application of photocatalysis technology, the activity and stability of photocatalytic materials are crucial.

[0004] As is well known in the art, the preparation of composite semiconductor photocatalytic materials is one of the effective methods to prevent the recombination of photo-generated electrons and holes and improve the photocatalytic efficiency. At the same time, existing research shows that Bi 2 O(OH) 2 SO 4 is a potential excellent photocatalytic material. Therefore, combining the nano-titanium dioxide TiO 2 and bismuth oxyhydroxysulfate Bi 2 O(OH) 2 SO 4 of the two semiconductors is expected to improve the stability and photocatalytic efficiency of the material.

[0005] However, the current preparation methods of nano-TiO 2 mainly include chemical reduction method, chemical precipitation method and vapor deposition method. Bi 2 O(OH) 2 SO 4 mostly adopts the homogeneous hydrothermal method. Although the above methods can prepare single nano-TiO 2 and Bi 2 O(OH) 2 SO 4 , when preparing the TiO 2 -Bi 2 O(OH) 2 SO 4 composite, usually one or two single semiconductors are first prepared and then physically or chemically compounded. The steps are cumbersome, and it is difficult for the two semiconductors to form an atomic or molecular heterostructure, resulting in poor compounding effect.

[0006] Accordingly, it is necessary to develop a preparation method of TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite with simple steps, convenient operation and good composite effect. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite based on a synthesis strategy of the synergistic effect of hydrolysis crystallization reaction and heterogeneous interface in-situ redox reaction, preparing TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite, and the preparation steps are simple, the operation is convenient, and the composite effect between TiO 2 and Bi 2 O(OH) 2 SO 4 is good.

[0008] The present invention adopts the following technical solutions to solve the above technical problems: A method for preparing TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite, adding sodium bismuthate dihydrate, sodium sulfite and titanium sulfate into a hydrothermal reaction kettle containing distilled water to obtain a solid-liquid mixture; under hydrothermal conditions, through the synergistic effect of the hydrolysis crystallization reaction of titanium sulfate and the heterogeneous interface in-situ redox reaction of sodium bismuthate dihydrate, preparing TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite, and the reaction process is as follows: .

[0009] As one of the preferred embodiments of the present invention, the molar ratio of sodium bismuthate dihydrate, sodium sulfite and titanium sulfate is 2:2:1.

[0010] As one of the preferred embodiments of the present invention, the solid-liquid mixture reacts for 6 - 30 h under hydrothermal conditions of 190 °C.

[0011] As one of the preferred embodiments of the present invention, after the hydrothermal reaction, it further includes the steps of centrifugal separation of the reaction product, washing with distilled water, and vacuum drying, and finally obtaining the TiO 2 -Bi2 O(OH) 2 SO 4 nanocomposite

[0012] As one of the preferred embodiments of the present invention, the specific conditions for the vacuum drying are: vacuum drying for 2 h at 60 °C and a vacuum degree of 0.1 Mpa.

[0013] As one of the preferred embodiments of the present invention, the finally obtained TiO 2 -Bi 2 O(OH) 2 SO 4 In the nanocomposite product, the average grain size of TiO 2 is 11.0 - 18.1 nm, and the average grain size of Bi 2 O(OH) 2 SO 4 is 87.2 - 87.4 nm.

[0014] Reaction principle: Sodium bismuthate dihydrate is a poorly soluble solid substance, which is converted into Bi 2 O(OH) 2 SO 4 through a heterogeneous interface in-situ redox reaction; among them, sodium bismuthate dihydrate acts as a sacrificial template, and Bi 2 O(OH) 2 SO 4 is generated on the surface of the template; at the same time, the hydrated titanium dioxide solid produced by the hydrolysis of Ti(SO 4 ) 2 in the aqueous solution is also deposited on the surface of the sodium bismuthate dihydrate solid template and further crystallizes into titanium dioxide crystals, thus generating the TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite. In the above reaction system, the hydrolysis reaction of Ti(SO 4 ) 2 produces hydrogen ions to provide an acidic environment, which ensures that the reduction product of sodium bismuthate dihydrate is bismuthyl hydroxy sulfate Bi 2 O(OH) 2 SO 4 . At the same time, the interfacial redox reaction of sodium bismuthate dihydrate can generate hydroxide ions, promoting the hydrolysis reaction of Ti(SO 4 ) 2 . The hydrolysis reaction of Ti(SO 4 ) 2 and the interfacial redox reaction of sodium bismuthate dihydrate act synergistically to promote the two reactions to proceed completely, and finally TiO 2 -Bi2 O(OH) 2 SO 4 Nanocomposite

[0015] The advantages of the present invention compared with the prior art are as follows: (1) Based on the synthesis strategy of the synergistic effect of hydrolysis crystallization reaction and heterogeneous interface in-situ redox reaction, the present invention realizes the "one-step" preparation of TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite, with simple preparation steps and convenient operation; (2) During the preparation of the composite of the present invention, when hydrated titanium dioxide solid is generated, it is deposited on the sodium bismuthate dihydrate solid template. At the same time, the sodium bismuthate dihydrate solid is in-situ transformed into Bi 2 O(OH) 2 SO 4 , so Bi 2 O(OH) 2 SO 4 and TiO 2 can effectively form an atomic or molecular heterostructure, with good composite effect; (3) During the preparation of the composite of the present invention, the hydrolysis reaction of Ti(SO 4 ) 2 produces hydrogen ions to provide an acidic environment, which ensures that the reduction product of sodium bismuthate dihydrate is bismuthyl hydroxy sulfate Bi 2 O(OH) 2 SO 4 ; at the same time, the interfacial redox reaction of sodium bismuthate dihydrate can produce hydroxide ions, promoting the hydrolysis reaction of Ti(SO 4 ) 2 ; (4) The preparation process of the composite of the present invention is easy to control and reduces the agglomeration of product particles (in-situ transformation and deposition on the solid surface can inhibit the migration of product particles and reduce polymerization and agglomeration), which is easy for industrial production. Brief Description of the Drawings

[0016] Figure 1 is the TEM image of the product prepared in Example 2 of the present invention (in the figure, the scale bar length is 500 nm); Figure 2 is the XRD pattern of the products prepared in each example and comparative example of the present invention (referenced by the XRD of titanium dioxide and bismuthyl hydroxy sulfate). Detailed Embodiments

[0017] The following is a detailed description of the embodiments of the present invention. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. At the same time, the reagent products and experimental methods used in the following examples, comparative examples, and experimental examples, unless otherwise specified, are conventional reagents or methods in the art and will not be elaborated further.

[0018] Example 1 A method for preparing a TiO 2 -Bi 2 O(OH) 2 SO 4 nano - composite: (1) Add 0.01 mol of sodium bismuthate dihydrate, 0.01 mol of sodium sulfite, and 0.005 mol of titanium sulfate to a 50 - ml hydrothermal reaction kettle containing 40 ml of distilled water to obtain a solid - liquid mixture.

[0019] (2) React the solid - liquid mixture obtained in step (1) under hydrothermal conditions at 190 °C for 6 h. Through the synergistic effect of the hydrolysis and crystallization reaction of titanium sulfate and the heterogeneous - interface in - situ redox reaction of sodium bismuthate dihydrate, prepare TiO 2 -Bi 2 O(OH) 2 SO 4 , and the reaction process is as follows: .

[0020] (3) Centrifuge, wash with distilled water, and vacuum - dry the product obtained in step (2) at 60 °C and a vacuum degree of 0.1 Mpa for 2 h to obtain the target product TiO 2 -Bi 2 O(OH) 2 SO 4 nano - composite.

[0021] Example 2 A method for preparing a TiO 2 -Bi 2 O(OH) 2 SO 4 nano - composite: (1) Add 0.01 mol of sodium bismuthate dihydrate, 0.01 mol of sodium sulfite, and 0.005 mol of titanium sulfate to a 50 - ml hydrothermal reaction kettle containing 40 ml of distilled water to obtain a solid - liquid mixture.

[0022] (2) React the solid-liquid mixture obtained in step (1) under hydrothermal conditions at 190 °C for 10 h. Through the synergistic effect of the hydrolysis and crystallization reaction of titanium sulfate and the heterogeneous interface in-situ redox reaction of sodium bismuthate dihydrate, TiO 2 -Bi 2 O(OH) 2 SO 4 is prepared. The reaction process is as follows: .

[0023] (3) Centrifuge, wash with distilled water, and vacuum dry the product obtained in step (2) at 60 °C and a vacuum degree of 0.1 Mpa for 2 h to obtain the target product TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite.

[0024] Example 3 A method for preparing TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite by a synergistic reaction: (1) Add 0.01 mol of sodium bismuthate dihydrate, 0.01 mol of sodium sulfite, and 0.005 mol of titanium sulfate to a 50 ml hydrothermal reaction kettle containing 40 ml of distilled water to obtain a solid-liquid mixture.

[0025] (2) React the solid-liquid mixture obtained in step (1) under hydrothermal conditions at 190 °C for 20 h. Through the synergistic effect of the hydrolysis and crystallization reaction of titanium sulfate and the heterogeneous interface in-situ redox reaction of sodium bismuthate dihydrate, TiO 2 -Bi 2 O(OH) 2 SO 4 is prepared. The reaction process is as follows: .

[0026] (3) Centrifuge, wash with distilled water, and vacuum dry the product obtained in step (2) at 60 °C and a vacuum degree of 0.1 Mpa for 2 h to obtain the target product TiO 2 -Bi 2 O(OH) 2 SO 4 nanocomposite.

[0027] Example 4 A method for preparing TiO 2 -Bi 2 O(OH) 2 SO4 Method for nano - composite: (1) Add 0.01 mol of sodium bismuthate dihydrate, 0.01 mol of sodium sulfite, and 0.005 mol of titanium sulfate to a 50 - ml hydrothermal reactor containing 40 ml of distilled water to obtain a solid - liquid mixture.

[0028] (2) React the solid - liquid mixture obtained in step (1) under hydrothermal conditions at 190 °C for 30 h. Through the synergistic effect of the hydrolysis and crystallization reaction of titanium sulfate and the heterogeneous - interface in - situ redox reaction of sodium bismuthate dihydrate, prepare TiO 2 -Bi 2 O(OH) 2 SO 4 , and the reaction process is as follows: .

[0029] (3) Centrifuge, wash with distilled water, and vacuum - dry the product obtained in step (2) at 60 °C and a vacuum degree of 0.1 Mpa for 2 h to obtain the target product TiO 2 -Bi 2 O(OH) 2 SO 4 nano - composite.

[0030] Comparative example A method for preparing a composite in this comparative example is basically the same as that in Example 2, and the main difference is that titanium sulfate is not added.

[0031] Experimental example 1 Place the product prepared in the above - mentioned example (taking Example 2 as an example) under a transmission electron microscope (TEM) for observation, and the results are as Figure 1 shown.

[0032] From Figure 1 it can be seen that TiO 2 O(OH) 2 SO 4 (small particles) is loaded on the surface of Bi 2 O(OH) 2 -Bi 2 O(OH) 2 SO 4 (large particles), indicating that the TiO

[0033] Experimental example 2 Perform X - ray diffraction analysis (XRD analysis) on the products obtained in the above - mentioned examples and comparative examples, and the results are as Figure 2 shown.

[0034] Figure 2XRD patterns of the products prepared in the embodiments and comparative examples of the present invention, with titanium dioxide (PDF#84-1286) and bismuthyl hydroxy sulfate (PDF#76-1102) as references. From Figure 2 it can be seen that in the XRD patterns of the products of each embodiment, there are obvious diffraction peaks of TiO 2 and Bi 2 O(OH) 2 SO 4 , and there are no diffraction peaks of other substances, indicating that the products of each embodiment are only composed of TiO 2 and Bi 2 O(OH) 2 SO 4 crystals; while in the XRD pattern of the product obtained in the comparative example, there is no characteristic diffraction peak of Bi 2 O(OH) 2 SO 4 , indicating that the product of the comparative example is not Bi 2 O(OH) 2 SO 4 crystal, but other substances; the above XRD analysis shows that in the absence of "titanium sulfate", an acidic environment cannot be provided, and sodium bismuthate dihydrate and sodium sulfite cannot react to obtain Bi 2 O(OH) 2 SO 4 product.

[0035] In addition, according to the XRD analysis of the products of Examples 1, 2, 3, and 4, calculated using the Scherrer formula, in the products of Examples 1, 2, 3, and 4: the average grain sizes of TiO 2 are 11.0 nm, 13.3 nm, 16.4 nm, and 18.1 nm respectively, and the average grain sizes of Bi 2 O(OH) 2 SO 4 are 87.2 nm, 87.3 nm, 87.4 nm, and 87.4 nm respectively; it shows that with the extension of the reaction time, the average grain size of TiO 2 in the product increases slowly, but the average grain size of Bi 2 O(OH) 2 SO 4 hardly changes.

[0036] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction, characterized in that: Sodium bismuthate dihydrate, sodium sulfite and titanium sulfate are added to a hydrothermal reactor containing distilled water to obtain a solid-liquid mixture; the solid-liquid mixture is subjected to the synergistic effect of the hydrolysis and crystallization reaction of titanium sulfate and the in-situ redox reaction of the heterogeneous interface of sodium bismuthate dihydrate to prepare a TiO2-Bi2O(OH)2SO4 nanocomposite under hydrothermal conditions, and the reaction process is as follows: 。 2. The method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction according to claim 1, characterized in that: The molar ratio of the sodium bismuthate dihydrate, sodium sulfite and titanium sulfate is 2:2:

1.

3. The method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction according to claim 1, characterized in that: The solid-liquid mixture is reacted under hydrothermal conditions at 190° C. for 6 to 30 hours.

4. The method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction according to any one of claims 1 to 3, characterized in that: After the hydrothermal reaction, the process also includes the steps of centrifugal separation of the reaction product, washing with distilled water, and vacuum drying, and finally obtaining the TiO2-Bi2O(OH)2SO4 nanocomposite.

5. The method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction according to claim 4, characterized in that: The specific conditions of the vacuum drying are: vacuum drying at 60° C. and 0.1 MPa vacuum degree for 2 h.

6. The method for preparing TiO2-Bi2O(OH)2SO4 nanocomposite by synergistic reaction according to claim 4, characterized in that: In the final TiO2-Bi2O(OH)2SO4 nanocomposite product, the average grain size of TiO2 is 11.0~18.1nm, and the average grain size of Bi2O(OH)2SO4 is 87.2~87.4 nm.

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