A preparation method of a sheet-shaped bismuth titanate catalyst material doped with Nb element

Abstract

The application discloses a preparation method of a sheet-shaped Nb element doped modified bismuth titanate catalyst material. 3‑x Nb x O 12 , wherein 0.15<=x<=0.40, the molar ratio of Bi, Ti and Nb is taken as bismuth oxide, titanium dioxide and niobium pentoxide; step two: the raw materials in step one and the mass ratio of the molten salt are mixed, then the mixture is put into a crucible and fully grinded to obtain a mixture; step three: the mixture prepared in step two is fired in a muffle furnace, and a light yellow product is obtained after cooling; step four: the light yellow product prepared in step three is washed with deionized water, filtered and dried to obtain a sheet-shaped Nb element doped bismuth titanate catalyst powder. The technology can significantly improve the structural uniformity, defect concentration and piezoelectric response activity of the material, greatly reduce the energy consumption and time cost, provides an efficient path for large-scale production of high-performance catalysts, and has a wide market prospect.

Description

Technical Field

[0001] This invention relates to the field of ceramic nanocatalytic material preparation technology, and in particular to a method for preparing a sheet-like Nb-doped bismuth titanate catalyst material. Background Technology

[0002] With rapid industrialization, large quantities of organic pollutants such as dyes, pesticides, and pharmaceutical wastewater are being discharged, posing a severe challenge to the ecological and human environment. Piezoelectric catalyst technology, as a novel degradation method, utilizes piezoelectric materials to capture mechanical vibrational energy, causing deformation and inducing internal polarization. This generates bound charges on the material surface, driving redox reactions and achieving pollutant degradation. Among numerous candidate materials, layered perovskite-structured bismuth titanate (Bi4Ti3O4) stands out. 12 Due to its unique crystal structure, suitable band structure, and good chemical stability, it has become a research hotspot. Its structure consists of a fluorite layer [Bi₂O₂]. 2+ With the perovskite layer [Bi2Ti3O] 10 ] 2- Alternating stacking along the c-axis forms a natural superlattice. This layered feature facilitates carrier migration and separation, while the TiO6 octahedron imparts intrinsic piezoelectricity. However, pure-phase Bi4Ti3O 12 The core bottleneck in piezoelectric and photocatalytic applications remains the excessively fast recombination rate of photogenerated carriers, which limits catalytic efficiency.

[0003] To improve Bi4Ti3O 12 To improve its catalytic performance, researchers have explored various modification methods. Among them, CN118045582A uses titanium foil as a template and titanium source to prepare Bi / Bi4Ti3O4 via a hydrothermal method. 12 Heterojunction materials are used, but their preparation process requires the removal of the template in the later stage, which can easily leave impurities and damage the structural integrity. CN108706632A prepared regularly shaped Bi4Ti3O using a secondary hydrothermal method. 12While nanosheets are used in this process, which does not require the addition of surfactants, precise control of mineralizer concentration and reaction time is necessary, and the preparation process is complex. CN105597751A synthesizes sheet-like gadolinium-doped bismuth titanate catalysts using a sol-gel-hydrothermal method, achieving a maximum degradation efficiency of 93.8% for 10 mg / L methyl orange solution in 140 min, indicating room for improvement in catalytic performance. CN107115856A provides a method for preparing sheet-like bismuth titanate-bismuth oxychloride composite materials, obtaining the catalyst through a combination of calcination and ion exchange methods. This method is complex and lengthy, and fluctuations in hydrochloric acid concentration and stirring time in the ion exchange method can lead to uneven nanosheet growth and instability. CN108479746A uses bismuth nitrate pentahydrate and TiO2 as raw materials, with glacial acetic acid and deionized water as the positive and negative solvents, respectively, to prepare nanosheet-like bismuth titanate photocatalysts through mixing, stirring, filtration, washing, and calcination. However, the relatively thick nanosheets result in low catalytic performance. CN107008473A describes a method for preparing bismuth titanate nanosheets via a molten salt method, followed by the vertical growth of bismuth oxychloride nanosheets on their surface using bismuth nitrate and sodium chloride via a hydrothermal method, thus forming a bismuth titanate / bismuth oxychloride nanosheet composite catalyst. However, this method is complex and not suitable for large-scale production. Some literature, such as "Nb-doped Bi₄Ti₃O₄", also mentions this method. 12 Study on Microstructure and Dielectric Properties of Ceramics, Nb-Modified Bi4Ti3O 12 Research on High-Temperature Piezoelectric Ceramics, Sr and Nb Composite Doped Bi4Ti3O 12 Research on high-temperature piezoelectric ceramics, "Bi4Ti3O" 12 The paper "Preparation and Performance Study of Nb-doped Ferroelectric Ceramics and Thin Films" (patent CN117548095B) describes the preparation of ceramic samples using a traditional solid-state reaction method. Raw materials were prepared according to stoichiometric ratios and reacted at 1000–1200℃. The microstructure and electrical properties were studied. However, this method requires high temperatures, resulting in high energy consumption and is environmentally unfriendly. The paper also discusses La / Nb doping of Bi₄Ti₃O₄. 12 The study, "Influence of Niobium Doping on Ferroelectric Properties and Fatigue Characteristics of Thin Films with MFS Structure," employed the sol-gel method to prepare B-site doped Bi₄Ti₄ on Pt / Ti / SiO₂ / p-Si substrates and p-Si substrates, respectively. 3-y Nb y O 12 Ferroelectric thin films can be produced, but this method has high requirements for equipment, temperature, and time in the process flow. Although the above literature uses B-site doping with Nb to prepare Bi₄Ti₃O₃... 12 However, its catalytic performance was not studied. CN 117548095 A used a solvothermal method to control the amount of Nb added to obtain Bi4Ti with different component contents.(3-x) Nb x O 12 Photo / piezoelectric catalytic materials exist, but their nanosheet development is incomplete. This invention employs a simple molten salt method, utilizing a low-temperature, liquid-phase reaction environment to control the NaCl-KCl salt ratio, thereby altering the molten salt viscosity and Cl... - Concentration, to achieve Nb 5+ The efficient doping and precise control of the sheet-like morphology resulted in two-dimensional nanosheets of Nb-doped Bi₄Ti₃O₄. 12 The catalyst material has a regular sheet-like structure, with its monomer nanosheets having a diameter of 0.08–0.73 μm and a thickness of 10–40 nm. This two-dimensional geometry endows the material with anisotropy, efficiently converting mechanical deformation into strong piezoelectric polarization. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing sheet-like Nb-doped bismuth titanate catalyst materials that is low in cost, simple in process, and has excellent performance.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0007] Step 1: According to the chemical formula Bi4Ti 3-x Nb x O 12 The molar ratio of Bi, Ti, and Nb is 0.15≤x≤0.40, and the molar ratio of Bi, Ti, and Nb is bismuth oxide, titanium dioxide, and niobium pentoxide.

[0008] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0009] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0010] Step 4: Wash, filter and dry the pale yellow product obtained in Step 3 with deionized water to obtain sheet-like Nb-doped bismuth titanate catalyst powder.

[0011] The catalyst powder obtained in step four has a uniform particle size distribution, and its shape is square or rectangular. The average size is 0.24-0.37 μm in length, 0.18-0.24 μm in width, and 20-35 nm in height.

[0012] In step two, the mass ratio of raw material to molten salt is 1:2 to 4, and the grinding time is 1 to 3 hours.

[0013] In step two, the molten salt is sodium chloride and potassium chloride in a molar ratio of 1:1.

[0014] In step three, the heating rate is 3-5℃ / min, the temperature is 700-900℃, and the holding time is 1-3h.

[0015] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0016] In step four, the drying temperature is 65–85°C and the drying time is 8–12 hours.

[0017] The present invention has the following beneficial effects:

[0018] (1) The two-dimensional nanosheet-shaped Nb-doped Bi4Ti3O provided by the present invention 12 The catalyst material exhibits a highly regular sheet-like morphology, with monomer nanosheets ranging from 0.08 to 0.73 μm in diameter and only 10 to 40 nm in thickness. This two-dimensional geometry endows the material with significant anisotropy, enabling it to efficiently convert external mechanical deformation into strong piezoelectric polarization, thereby greatly enhancing piezoelectric catalytic activity. Furthermore, Nb doping not only inhibits excessive grain growth and strengthens lattice stability but also imparts good dispersibility and easy separability, demonstrating excellent cycle durability in practical catalytic applications.

[0019] (2) This invention employs a simple molten salt method, which involves oxidizing Nb in a specific molten salt environment (NaCl / KCl, molar ratio 1:1). 5+ The doping behavior is deeply coupled with the crystal plane guidance effect of the molten salt medium, constructing a three-in-one synergistic regulation mechanism of "chemisorption-transport-doping". The innovation of this mechanism lies in: Cl in the molten salt - Ions exhibit strong chemisorption on specific crystal planes, simultaneously inducing and locking into highly ordered, anisotropic two-dimensional nanosheet morphologies. This morphology is an ideal carrier for achieving efficient mechanical-to-electrical energy conversion and generating a strong piezoelectric response. Simultaneously, the uniform transport environment provided by the molten salt allows Nb... 5+ It can achieve atomic-level dispersed doping, effectively suppressing abnormal grain growth and enhancing lattice integrity, thereby simultaneously improving the stability and service life of the material at the intrinsic structure level.

[0020] (3) By adjusting the ratio of NaCl to KCl, the viscosity of the molten salt and the Cl can be further adjusted. - Concentration, thereby achieving Nb 5+This method achieves efficient doping and precise control of the two-dimensional sheet-like morphology. It fundamentally avoids the high cost and multiple steps associated with traditional template methods or complex morphology modification techniques, simultaneously optimizing the piezoelectric activity and charge transport efficiency of the material in a single step. Therefore, this invention not only significantly improves the structural uniformity, defect controllability, and piezoelectric response activity of the material, but also possesses comprehensive advantages such as simple process, low energy consumption, short cycle time, and suitability for large-scale production, providing an efficient and reliable technical route for the preparation of high-performance piezoelectric and photocatalytic materials.

[0021] (4) This invention intentionally modifies the catalyst material by doping Nb at the B site, constructing an enhancement mechanism of "lattice distortion-piezoelectric polarization-charge separation" to achieve a breakthrough improvement in catalytic performance. When Nb 5+ Replace Ti 4+ When ions enter the crystal lattice, they cause local lattice distortion and stress, reducing the lattice symmetry. This makes the material more susceptible to ion displacement under external mechanical stress, resulting in stronger spontaneous polarization or a larger piezoelectric response. This means that a strong built-in electric field can be established within the material, driving charge separation and ultimately yielding catalyst materials with excellent catalytic performance.

[0022] (5) The Nb-doped Bi4Ti3O provided by the present invention 12 Catalyst materials utilize a charge compensation mechanism to form positively charged oxygen vacancies on the material surface. These oxygen vacancies not only serve as traps for capturing photogenerated or piezoelectrically generated electrons, optimizing carrier separation and migration efficiency, but also act as active sites for adsorbing and activating reactants, greatly enhancing catalytic efficiency. Attached Figure Description

[0023] Figure 1 These are SEM images of the catalyst powder prepared in Example 1 of this invention;

[0024] Figure 2 This is the X-ray diffraction pattern of the catalyst powder prepared in Example 1 of this invention;

[0025] Figure 3 This is a graph showing the relationship between the efficiency of the catalyst powder prepared in Example 1 of this invention in degrading 10 mg / L methyl orange (MO) under ultrasonic conditions and time.

[0026] Figure 4 This is a graph showing the relationship between the efficiency of the catalyst powder prepared in Example 1 of this invention in degrading 10 mg / L methyl orange (MO) under light irradiation and time.

[0027] Figure 5 These are SEM images of the catalyst powder prepared in Example 2 of this invention;

[0028] Figure 6This is the X-ray diffraction pattern of the catalyst powder prepared in Example 2 of this invention;

[0029] Figure 7 These are SEM images of the catalyst powder prepared in Example 3 of this invention;

[0030] Figure 8 This is the X-ray diffraction pattern of the catalyst powder prepared in Example 3 of this invention;

[0031] Figure 9 Here is a SEM image of the catalyst powder prepared in Example 4 of this invention;

[0032] Figure 10 This is the X-ray diffraction pattern of the catalyst powder prepared in Example 4 of this invention;

[0033] Figure 11 These are SEM images of the catalyst powder prepared in Example 5 of this invention;

[0034] Figure 12 This is the X-ray diffraction pattern of the catalyst powder prepared in Example 5 of this invention. Detailed Implementation

[0035] To further illustrate the present invention, the technical means and effects adopted to achieve the intended purpose of the invention, the present invention will be described in detail below with reference to preferred embodiments.

[0036] Example 1

[0037] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0038] Step 1: According to the chemical formula Bi4Ti 3-x Nb x O 12 Where x=0.40, the molar ratio of Bi, Ti, and Nb is 4:2.60:0.40. Weigh out 1.864g of bismuth oxide, 0.415g of titanium dioxide, and 0.106g of niobium pentoxide.

[0039] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0040] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0041] Step 4: Wash, filter, and dry the pale yellow product obtained in Step 3 with deionized water to obtain flake-like Bi4Ti. 2.60 Nb 0.4 O 12 Catalyst material powder.

[0042] In step two, the mass ratio of raw material to molten salt is 1:3, and the grinding time is 2 hours.

[0043] In step two, the molten salt consists of 3.147g of sodium chloride and 4.008g of potassium chloride.

[0044] In step three, the heating rate is 3℃ / min, the temperature is 800℃, and the holding time is 2h.

[0045] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0046] In step four, the drying temperature is 80℃ and the drying time is 12 hours.

[0047] like Figure 1 As shown, the catalyst powder prepared in this embodiment exhibits a regular two-dimensional nanosheet structure under a scanning electron microscope, with an average length of 0.24 μm, a width of 0.18 μm, and a height of 30 nm.

[0048] like Figure 2 As shown, the characteristic peak positions and intensities of the catalyst powder prepared in this embodiment coincide with those of bismuth titanate (PDF#97-015-1886), and there are no other crystalline phase impurity peaks present, indicating that bismuth titanate still maintains a pure phase, and Nb element has been successfully doped into the BTO lattice with good crystallinity.

[0049] like Figure 3 As shown, the catalyst powder prepared in this embodiment was tested under ultrasonic conditions (45KHz, 360W) to degrade 10mg / L methyl orange MO. The degradation rate of the dye was nearly 100%, indicating that the material has good application performance in piezoelectric catalysis.

[0050] like Figure 4 As shown, the catalyst powder prepared in this embodiment showed a degradation rate of nearly 100% for 10 mg / L methyl orange (MO) under light irradiation (300 W xenon lamp), indicating that the material has good application performance in the field of photocatalysis.

[0051] Example 2

[0052] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0053] Step 1: According to the chemical formula Bi4Ti 3-x Nb x O 12Where x=0.15, the molar ratio of Bi, Ti, and Nb is 4:2.85:0.15. Weigh out 1.864g of bismuth oxide, 0.455g of titanium dioxide, and 0.040g of niobium pentoxide.

[0054] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0055] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0056] Step 4: Wash, filter, and dry the pale yellow product obtained in Step 3 with deionized water to obtain flake-like Bi4Ti. 2.85 Nb 0.15 O 12 Catalyst material powder.

[0057] In step two, the mass ratio of raw material to molten salt is 1:2, and the grinding time is 1 hour.

[0058] In step two, the molten salt consists of 2.073g of sodium chloride and 2.645g of potassium chloride.

[0059] In step three, the heating rate is 3℃ / min, the temperature is 700℃, and the holding time is 1h.

[0060] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0061] In step four, the drying temperature is 85℃ and the drying time is 12 hours.

[0062] like Figure 5 As shown, the catalyst powder prepared in this embodiment exhibits a regular two-dimensional nanosheet or rectangular sheet structure under a scanning electron microscope, with an average length of 0.30 μm, a width of 0.22 μm, and a height of 32 nm.

[0063] like Figure 6 As shown, the characteristic peak positions and intensities of the catalyst powder prepared in this embodiment coincide with those of bismuth titanate (PDF#97-015-1886), and there are no other crystalline phase impurity peaks present, indicating that the product is composed of pure phase bismuth titanate and has good crystallinity.

[0064] Example 3

[0065] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0066] Step 1: According to the chemical formula Bi4Ti 3-x Nbx O 12 Where x=0.4, the molar ratio of Bi, Ti, and Nb is 4:2.60:0.40. Weigh out 1.864g of bismuth oxide, 0.415g of titanium dioxide, and 0.106g of niobium pentoxide.

[0067] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0068] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0069] Step 4: Wash, filter, and dry the pale yellow product obtained in Step 3 with deionized water to obtain flake-like Bi4Ti. 2.60 Nb 0.40 O 12 Catalyst material powder.

[0070] In step two, the mass ratio of raw material to molten salt is 1:4, and the grinding time is 3 hours.

[0071] In step two, the molten salt consists of 4.196g of sodium chloride and 5.344g of potassium chloride.

[0072] In step three, the heating rate is 5℃ / min, the temperature is 900℃, and the holding time is 3h.

[0073] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0074] In step four, the drying temperature is 65℃ and the drying time is 10 hours.

[0075] like Figure 7 As shown, the catalyst powder prepared in this embodiment exhibits a regular two-dimensional nanosheet or rectangular sheet structure under a scanning electron microscope, with an average length of 0.29 μm, a width of 0.21 μm, and a height of 28 nm.

[0076] like Figure 8 As shown, the characteristic peak positions and intensities of the catalyst powder prepared in this embodiment coincide with those of bismuth titanate (PDF#97-015-1886), and there are no other crystalline phase impurity peaks present, indicating that the product is pure phase bismuth titanate with good crystallinity.

[0077] Example 4

[0078] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0079] Step 1: According to the chemical formula Bi4Ti3-x Nb x O 12 Where x=0.3, the molar ratio of Bi, Ti, and Nb is 4:2.70:0.30. Weigh out 1.864g of bismuth oxide, 0.431g of titanium dioxide, and 0.080g of niobium pentoxide.

[0080] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0081] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0082] Step 4: Wash, filter, and dry the pale yellow product obtained in Step 3 with deionized water to obtain flake-like Bi4Ti. 2.70 Nb 0.30 O 12 Catalyst material powder.

[0083] In step two, the mass ratio of raw material to molten salt is 1:3, and the grinding time is 2 hours.

[0084] In step two, the molten salt consists of 3.131 g of sodium chloride and 3.994 g of potassium chloride.

[0085] In step three, the heating rate is 4℃ / min, the temperature is 800℃, and the holding time is 2h.

[0086] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0087] In step four, the drying temperature is 85℃ and the drying time is 8 hours.

[0088] like Figure 9 As shown, the catalyst powder prepared in this embodiment exhibits a regular two-dimensional nanosheet or rectangular sheet structure under a scanning electron microscope, with an average length of 0.36 μm, a width of 0.24 μm, and a height of 35 nm.

[0089] like Figure 10 As shown, the characteristic peak positions and intensities of the catalyst powder prepared in this embodiment coincide with those of bismuth titanate (PDF#97-015-1886), and there are no other crystalline phase impurity peaks present, indicating that the product is pure phase bismuth titanate with good crystallinity.

[0090] Example 5

[0091] A method for preparing a sheet-like Nb-doped bismuth titanate catalyst material, characterized by comprising the following steps:

[0092] Step 1: According to the chemical formula Bi4Ti 3-x Nb x O 12 Where x=0.35, the molar ratio of Bi, Ti, and Nb is 4:2.60:0.45. Weigh out 1.864g of bismuth oxide, 0.423g of titanium dioxide, and 0.093g of niobium pentoxide.

[0093] Step 2: According to the mass ratio of raw materials to molten salt in Step 1, mix the molten salt with the raw materials in Step 1, and then grind them thoroughly in a crucible to obtain a mixture;

[0094] Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained.

[0095] Step 4: Wash, filter, and dry the pale yellow product obtained in Step 3 with deionized water to obtain flake-like Bi4Ti. 2.55 Nb 0.45 O 12 Catalyst material powder.

[0096] In step two, the mass ratio of raw material to molten salt is 1:3, and the grinding time is 2.5 hours.

[0097] In step two, the molten salt consists of 3.141g of sodium chloride and 3.999g of potassium chloride.

[0098] In step three, the heating rate is 3℃ / min, the temperature is 850℃, and the holding time is 1.5h.

[0099] The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

[0100] In step four, the drying temperature is 80℃ and the drying time is 12 hours.

[0101] like Figure 11 As shown, the catalyst powder prepared in this embodiment exhibits a regular two-dimensional nanosheet or rectangular sheet structure under a scanning electron microscope, with an average length of 0.37 μm, a width of 0.23 μm, and a height of 20 nm.

[0102] like Figure 12 As shown, the characteristic peak positions and intensities of the catalyst powder prepared in this embodiment coincide with those of bismuth titanate (PDF#97-015-1886), and there are no other crystalline phase impurity peaks present, indicating that the product is pure phase bismuth titanate with good crystallinity.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present invention are included within the protection scope of the present invention.

Claims

1. The application of a sheet-like Nb-doped bismuth titanate catalyst material in the degradation of methyl orange under ultrasonic or light irradiation conditions, characterized in that... The preparation method of the sheet-like Nb-doped bismuth titanate catalyst material includes the following steps: Step 1: According to the chemical formula Bi4Ti 3-x Nb x O 12 The molar ratio of Bi, Ti, and Nb with x=0.40 is determined by weighing bismuth oxide, titanium dioxide, and niobium pentoxide. Step 2: Following the mass ratio of raw materials to molten salt in Step 1 of 1:2 to 4, mix the molten salt with the raw materials from Step 1 and grind them thoroughly in a crucible to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a muffle furnace and calcine it. After cooling, a pale yellow product is obtained. Step 4: Wash, filter and dry the pale yellow product obtained in Step 3 with deionized water to obtain sheet-like Nb-doped bismuth titanate catalyst powder. The catalyst powder obtained in step four has a uniform particle size distribution, and its shape is square or rectangular, with an average length of 0.24-0.37 μm, a width of 0.18-0.24 μm, and a height of 20-35 nm. The grinding time in step two is 1 to 3 hours; In step three, the heating rate is 3-5℃ / min, the temperature is 700-900℃, and the holding time is 1-3h. The ultrasonic conditions are 45 kHz and 360 W. The illumination conditions are 300W xenon lamp illumination; The concentration of methyl orange (MO) is 10 mg / L; In step two, the molten salt is sodium chloride and potassium chloride in a molar ratio of 1:

1.

2. The application according to claim 1, characterized in that: The washing method in step four is as follows: wash with deionized water at 50°C until no white precipitate is formed when tested with silver nitrate solution.

3. The application according to claim 1, characterized in that: In step four, the drying temperature is 65–85°C and the drying time is 8–12 hours.

Images