A core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, a preparation method and application thereof

Abstract

The application discloses a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped energy band structure and a preparation method and application thereof, and the preparation method comprises the following steps: step one, preparing carboxylated BaTiO3 nanoparticles; step two, adding the carboxylated BaTiO3 nanoparticles, an indium salt, C2H5NS and CH4N2O into distilled water, and then stirring on a magnetic stirrer to obtain a first mixed solution; step three, transferring the first mixed solution into an autoclave, and then obtaining a second mixed solution after heating reaction; step four, naturally cooling the second mixed solution to room temperature, and then obtaining the BaTiO3 / In2S3 heterojunction after washing, centrifugation and drying; and the core-shell nanoflower BaTiO3 / In2S3 heterojunction with the S-shaped energy band structure is applied to degradation of doxycycline hydrochloride, degradation of rhodamine B and reduction of Cr(VI) reaction as a photocatalyst, and a better degradation effect can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, and specifically relates to a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, its preparation method, and its application. Background Technology

[0002] With the acceleration of global industrialization and urbanization, water pollution has become a major challenge threatening the ecological environment and human health. Heavy metal ions and organic dyes in industrial wastewater, pesticide and fertilizer residues from agricultural activities, and antibiotics and microplastics in domestic sewage, among other complex pollutants, lead to eutrophication and the accumulation of toxic substances in water bodies. Traditional physical adsorption, chemical oxidation, and biodegradation technologies are ineffective in treating persistent organic pollutants (such as antibiotics, dyes, and heavy metals) due to their low efficiency, high cost, and tendency to generate secondary pollution. Against this backdrop, solar-driven photocatalysis technology is considered an ideal alternative due to its green and sustainable characteristics. However, traditional photocatalysts (such as TiO2) suffer from bottlenecks such as a narrow light absorption range (responding only to ultraviolet light), high carrier recombination rate, and poor stability, severely limiting their practical application. Summary of the Invention

[0003] One of the objectives of this invention is to provide a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, which has high photocatalytic degradation ability and reduction activity, and can improve catalytic efficiency.

[0004] Another objective of this invention is to provide a method for preparing core-shell nanoflower BaTiO3 / In2S3 heterojunctions with an S-shaped band structure. The method involves preparing core-shell nanoflower BaTiO3 / In2S3 heterojunctions with an S-shaped band structure via a hydrothermal method. The preparation method is simple, has high preparation efficiency, and low preparation cost.

[0005] This invention also provides an application of a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, which is used as a photocatalyst in the degradation of doxycycline hydrochloride, the degradation of rhodamine B, and the reduction of Cr(VI).

[0006] The technical solution provided by this invention is as follows:

[0007] A method for preparing a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-type band structure includes the following steps:

[0008] Step 1: Preparation of carboxylated BaTiO3 nanoparticles;

[0009] Step 2: After adding the carboxylated BaTiO3 nanoparticles, indium salt, C2H5NS and CH4N2O to distilled water, stir on a magnetic stirrer to obtain the first mixed solution;

[0010] Step 3: Transfer the first mixed solution into an autoclave, heat and react to obtain the second mixed solution;

[0011] Step 4: Cool the second mixed solution naturally to room temperature, and after washing, centrifugation, and drying, obtain the BaTiO3 / In2S3 heterojunction.

[0012] Preferably, in step one, the method for preparing carboxylated BaTiO3 nanoparticles is as follows:

[0013] Succinic anhydride was added to DMF and stirred until dissolved. Then, 3-aminopropyltriethoxysilane was added dropwise. The resulting mixture was stirred at room temperature, and then deionized water, DMF, and BaTiO3 were added. After stirring again at room temperature, the mixture was washed three times with distilled water and ethanol, respectively, and dried at 80°C to obtain carboxylated BaTiO3 nanoparticles.

[0014] Preferably, in step two, the molar ratio of carboxylated BaTiO3 nanoparticles, InCl3·4H2O, C2H5NS, CH4N2O and distilled water is 17:100:200:200:450.

[0015] Preferably, in step two, the stirring speed is 500 rpm and the stirring time is 30 min.

[0016] Preferably, the autoclave is a high-pressure autoclave with a polytetrafluoroethylene liner.

[0017] Preferably, in step three, the reaction is carried out at a temperature of 150°C to 180°C for 10 to 12 hours to obtain a second mixed solution.

[0018] Preferably, in step four, after washing with distilled water and ethanol three times in sequence, the mixture is dried at 60°C for 10-12 hours to obtain a BaTiO3 / In2S3 heterojunction.

[0019] A core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure is prepared using the aforementioned preparation method for core-shell nanoflower BaTiO3 / In2S3 heterojunctions with an S-shaped band structure.

[0020] An application of a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure is described, in which the core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure is used as a photocatalyst in the degradation of doxycycline hydrochloride, the degradation of rhodamine B, and the reduction of Cr(VI).

[0021] The beneficial effects of this invention are:

[0022] This invention constructs a flower-like In2S3 array on the surface of carboxyl-modified BaTiO3 nanoparticles (BTO NPs, with a particle size of about 200 nm) through in-situ growth, forming a core-shell heterojunction (BaTiO3 / In2S3) with BTO as the core and In2S3 as the shell. The performance improvement of this structure includes the following three aspects: (1) Band synergistic optimization: The broad spectrum response characteristics of BaTiO3 and the high visible light absorption efficiency of In2S3 complement each other, expanding the light absorption range to the ultraviolet-visible full spectrum; (2) S-shaped heterojunction charge transport path: A built-in electric field is formed at the interface, driving photogenerated electrons to migrate directionally from In2S3 to BaTiO3, and holes to transfer in the opposite direction, significantly suppressing carrier recombination and retaining strong redox ability; (3) Advantages of core-shell nanoflower morphology: The three-dimensional flower-like structure provides a high specific surface area and abundant active sites, enhancing the adsorption and reaction kinetics of pollutants. Attached Figure Description

[0023] Figure 1 shows scanning electron microscope and transmission electron microscope images of the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0024] Figure 1(a) is a scanning electron microscope image of In2S3 described in this invention.

[0025] Figure 1(b) is a scanning electron microscope image of the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0026] Figure 1(c) is a transmission electron microscope image of the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0027] Figure 1(d) is an EDS elemental mapping image of barium in the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0028] Figure 1(e) is an EDS elemental mapping image of titanium in the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0029] Figure 1(f) is an EDS elemental mapping image of oxygen in the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0030] Figure 1(g) is an EDS elemental mapping image of indium in the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0031] Figure 1(h) is an EDS elemental mapping image of sulfur in the BaTiO3 / In2S3 heterojunction prepared in the embodiment of the present invention.

[0032] Figure 2 X-ray diffraction patterns of BaTiO3, In2S3, and the BaTiO3 / In2S3 heterogeneity prepared in the embodiments of the present invention.

[0033] Figure 3 Infrared spectra of BaTiO3, In2S3, and the BaTiO3 / In2S3 heterojunction prepared in the embodiments of the present invention.

[0034] Figure 4 The graph shows the concentration changes of BaTiO3 / In2S3 heterojunction prepared in the embodiments of the present invention during the degradation of DH (doxycycline hydrochloride), the degradation of RhB (rhodamine B), and the reduction of Cr (VI).

[0035] Figure 5 The graph shows the kinetics of the degradation of DH (doxycycline hydrochloride), the degradation of RhB (rhodamine B), and the reduction of Cr(VI) by the BaTiO3 / In2S3 heterojunction prepared in the embodiments of the present invention.

[0036] Figure 6 The graph shows the concentration changes of Cr(VI) in the photocatalytic reduction of the BaTiO3 / In2S3-(1:3) heterojunction prepared in the embodiments of the present invention and the BaTiO3 / In2S3-(1:1) heterojunction prepared in the comparative example.

[0037] Figure 7 The images show the kinetic curves of the photocatalytic reduction of Cr(VI) by the BaTiO3 / In2S3-(1:3) heterojunction prepared in the embodiments of the present invention and the BaTiO3 / In2S3-(1:1) heterojunction prepared in the comparative example.

[0038] Figure 8 The images show the XRD patterns of the BaTiO3 / In2S3 heterojunction prepared in this embodiment of the invention before and after three cycle tests.

[0039] Figure 9 This is a diagram illustrating the photocatalytic mechanism of the present invention.

[0040] Figure 9 (A) is the band structure of the BaTiO3 / In2S3 heterojunction described in this invention.

[0041] Figure 9(B) refers to the band bending and built-in field at the contact interface in the dark in the BaTiO3 / In2S3 heterojunction described in this invention.

[0042] Figure 9 (C) represents the mechanism of DH degradation in the BaTiO3 / In2S3 S-type heterojunction under illumination as described in this invention. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0044] Barium titanate (BaTiO3), a typical piezoelectric material, has shown great potential in photocatalysis in recent years due to its internal spontaneous polarization field, which can effectively drive the separation of photogenerated electron-hole pairs and suppress carrier recombination. Indium sulfide (In2S3), as a narrow bandgap semiconductor (bandgap energy 2.0-2.5 eV), has significant advantages: firstly, its bandgap position is located in the ideal range for visible light absorption, capturing approximately 45% of the visible light energy in the solar spectrum, achieving efficient photon absorption and electron-hole pair generation; secondly, its carrier mobility is significantly higher than that of traditional metal sulfides and oxides, accelerating charge transfer to the catalyst surface to participate in the reaction; and thirdly, its inherent chemical stability resists corrosion in aqueous environments and under strong reaction conditions, ensuring long-term cyclic performance. Compared with existing photocatalytic materials, In2S3 exhibits significant superiority in light absorption efficiency, carrier transport capacity, and stability.

[0045] Based on the above characteristics, this invention provides a method for preparing a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, the specific implementation process of which is as follows.

[0046] I. Preparation of carboxylated BaTiO3 nanoparticles (Car-BaTiO3).

[0047] As a preferred method, the preparation of carboxylated BaTiO3 nanoparticles is as follows: succinic anhydride is added to DMF and stirred to dissolve. Then, 3-aminopropyltriethoxysilane is added dropwise. The resulting mixture is stirred at room temperature, and then deionized water, DMF, and BaTiO3 are added. After stirring again at room temperature, the mixture is washed three times with distilled water and ethanol, respectively, and dried at 80°C to obtain carboxylated BaTiO3 nanoparticles.

[0048] 2. After adding the carboxylated BaTiO3 nanoparticles, indium salt, C2H5NS and CH4N2O to distilled water, stir on a magnetic stirrer to obtain a first mixed solution.

[0049] The stirring speed was 500 rpm and the stirring time was 30 min.

[0050] As a preferred option, the molar ratio of carboxylated BaTiO3 nanoparticles, InCl3·4H2O, C2H5NS, CH4N2O and distilled water is 17:100:200:200:450.

[0051] 3. The first mixed solution is transferred into a high-pressure reactor lined with polytetrafluoroethylene and heated at 150℃~180℃ for 10h~12h to obtain the second mixed solution.

[0052] Fourth, the second mixed solution was naturally cooled to room temperature, and after washing, centrifugation and drying, BaTiO3 / In2S3 heterojunction was obtained.

[0053] As a preferred method, the material is washed three times with distilled water and ethanol, and then dried at 60°C for 10-12 hours to obtain a BaTiO3 / In2S3 heterojunction.

[0054] The present invention also provides a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, which is prepared by the preparation method of the core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure.

[0055] This invention also provides a method for applying a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, wherein the core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure is used as a photocatalyst in the degradation of doxycycline hydrochloride, the degradation of rhodamine B, and the reduction of Cr(VI).

[0056] The present invention provides a method for constructing a flower-like In2S3 array on the surface of carboxyl-modified BaTiO3 nanoparticles (BTO NPs, with a particle size of about 200 nm) through in-situ growth, forming a core-shell heterojunction (BaTiO3 / In2S3) with BTO as the core and In2S3 as the shell. The heterojunction structure design improves performance through the following mechanisms: (1) Band synergistic optimization: The broad spectral response characteristics of BaTiO3 and the high visible light absorption efficiency of In2S3 complement each other, extending the light absorption range to the ultraviolet-visible full spectrum; (2) S-shaped heterojunction charge transport path: A built-in electric field is formed at the interface, driving photogenerated electrons to migrate directionally from In2S3 to BaTiO3, and holes to transfer in the opposite direction, significantly suppressing carrier recombination and retaining strong redox ability; (3) Advantages of core-shell nanoflower morphology: The three-dimensional flower-like structure provides a high specific surface area and abundant active sites, enhancing the adsorption and reaction kinetics of pollutants.

[0057] The heterojunction material prepared via a one-step hydrothermal method exhibited excellent photocatalytic performance in experiments and maintained high stability even after recycling. This efficient and low-cost preparation process provides an innovative solution for the deep purification of industrial and medical wastewater, and has broad prospects for environmental governance and industrial applications.

[0058] The preparation method and application effects of the core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure provided by the present invention will be further explained below with reference to specific embodiments.

[0059] Example

[0060] 1 mmol of succinic anhydride was added to 171.8 mmol of DMF and stirred until dissolved. Then, 2 mmol of 3-aminopropyltriethoxysilane was added dropwise. The resulting mixture was stirred at room temperature for 3 h. Then, 0.33 mmol of deionized water, 21.57 mmol of DMF, and 0.13 mmol of BaTiO3 were added, and the mixture was stirred at room temperature for 6 h. The mixture was washed three times with distilled water and ethanol, respectively, and dried overnight at 80 °C to obtain carboxylated BaTiO3, labeled Car-BaTiO3.

[0061] 1 mmol of InCl3·4H2O, 2 mmol of C2H5NS, 2 mmol of CH4N2O, and 0.17 mmol of Car-BaTiO3 were added to 4.5 mmol of H2O to form a homogeneous solution. After stirring at room temperature for 30 min, the solution was transferred to a 100 mL autoclave lined with polytetrafluoroethylene and heated to 180 °C for 12 h. After naturally cooling to room temperature, the solution was washed three times with H2O and ethanol, centrifuged, and dried at 60 °C for 12 h to obtain a BaTiO3 / In2S3-(1:3) heterojunction.

[0062] Comparative Example

[0063] 1 mmol of succinic anhydride was added to 171.8 mmol of DMF and stirred until dissolved. Then, 2 mmol of 3-aminopropyltriethoxysilane was added dropwise. The resulting mixture was stirred at room temperature for 3 h. Then, 0.33 mmol of deionized water, 21.57 mmol of DMF, and 0.13 mmol of BaTiO3 were added, and the mixture was stirred at room temperature for 6 h. The mixture was washed three times with distilled water and ethanol, respectively, and dried overnight at 80 °C to obtain carboxylated BaTiO3, labeled Car-BaTiO3.

[0064] 1 mmol of InCl3·4H2O, 2 mmol of C2H5NS, 2 mmol of CH4N2O, and 0.5 mmol of Car-BaTiO3 were added to 4.5 mmol H2O to form a homogeneous solution. After stirring at room temperature for 30 min, the solution was transferred to a 100 mL autoclave lined with polytetrafluoroethylene and heated to 180 °C for 12 h. After naturally cooling to room temperature, the solution was washed three times with H2O and ethanol, centrifuged, and dried at 60 °C for 12 h to obtain a BaTiO3 / In2S3-(1:1) heterojunction.

[0065] As shown in Figures 1(a) and 1(b), the morphology and structure of the samples prepared in the examples were observed by SEM. It can be seen that pure In2S3 consists of aggregates composed of many nanosheets. When Car-BaTiO3 and In2S3 nanosheets were mixed in a suspension, a tightly bound BaTiO3 / In2S3 heterojunction was obtained through interaction. From the TEM image of the BaTiO3 / In2S3 heterojunction in Figure 1(c), many irregular In2S3 nanosheets can be clearly seen surrounding the spherical Car-BaTiO3, indicating that In2S3 was successfully prepared on the Car-BaTiO3 surface. The EDS elemental mapping diagrams in Figures 1(d) to (h) show that Ba, Ti, O, In, and S elements are uniformly distributed on the BaTiO3 / In2S3 surface, confirming that the uniform adhesion of In2S3 on BaTiO3 exhibits a uniform structural feature, which can lead to the formation of more active sites between the two materials, enhancing the catalytic ability of the composite material.

[0066] like Figure 2As shown, for pure In2S3, based on the standard card (JCPDS#84-1385), its diffraction peaks at 14.32°, 23.39°, 27.50°, 33.24°, 43.59° and 47.77° correspond to the (111), (220), (311), (400), (511) and (440) planes of the In2S3 standard spectrum (PDF:), respectively. For BaTiO3, the characteristic diffraction peaks at 44.9° and 45.4° (JCPDS#76-0744) indicate that BaTiO3 exists in the tetragonal phase, and its diffraction peaks at 22.237°, 31.495°, 38.893°, 45.371° and 56.275° correspond to the (100), (101), (111), (200) and (211) diffraction planes, respectively. For the heterojunction composite materials prepared in the examples, the XRD patterns clearly showed mixed diffraction peaks of In2S3 and BaTiO3, and the intensity of the main diffraction peak varied with the mass ratio of In2S3 to BaTiO3. For example, with the increase of In2S3 content, the intensity of the (200) diffraction peak of BaTiO3 gradually decreased, while the intensity of the diffraction peak of In2S3 increased rapidly. In short, the XRD results confirmed that In2S3 and BaTiO3 do indeed coexist in the composite photocatalyst, and no impure phases were observed in any samples.

[0067] Fourier transform infrared spectroscopy (FTIR) was used to confirm the heterojunction structure prepared in the examples, and the results are as follows: Figure 3 As shown. For BaTiO3, at 541 and 428 cm⁻¹ -1 The two typical absorption peaks at 1452 cm⁻¹ are attributed to the stretching and bending vibrations of Ti-O in BaTiO₃, respectively. -1 The peak at 1391 cm⁻¹ corresponds to the vibration of Ba-Ti-O. For In₂S₃, the peak at 1391 cm⁻¹ corresponds to the vibration of Ba-Ti-O. -1 The peak at 3400 cm⁻¹ corresponds to the In-S vibration. -1 and 1600cm -1 The diffraction peak is the OH vibration peak, 2800 cm⁻¹. -1 and 2900cm -1 The diffraction peaks are CH vibration peaks. Notably, the composite catalyst BaTiO3 / In2S3 exhibits diffraction peaks corresponding to Ti-O, Ba-Ti-O, and In-S, indicating that In2S3 was successfully composited with BaTiO3 and the prepared sample is relatively pure.

[0068] like Figure 4 As shown, to investigate the degradation effects of the BaTiO3 / In2S3 catalyst prepared in the examples on DH, RhB, and Cr(VI) within 30 min, a graph showing the change in pollutant concentration was plotted, where C...t C0 and C0 represent the instantaneous and initial concentrations of pollutants in the aqueous solution, respectively. This indicates a synergistic effect between BaTiO3 and In2S3, with noticeable changes in degradation rates observed when they act on DH, RhB, and Cr(VI), respectively. This effect may be due to the interaction between the two materials, such as band structure matching and effective electron-hole pair separation, thereby improving the utilization efficiency of photogenerated carriers and photocatalytic activity.

[0069] like Figure 5 As shown, in order to investigate the photodegradation kinetics of DH, RhB and Cr(VI) by the BaTiO3 / In2S3 catalyst prepared in the examples, the first-order kinetic equation ln(C) was used. t Simulation calculations are performed using / C0)=kt. Where C t C0 and C0 represent the instantaneous and initial concentrations of pollutants in the aqueous solution, respectively. k represents the degradation rate constant. The degradation of DH, RhB, and Cr(VI) by the BaTiO3 / In2S3 catalyst follows a first-order kinetic model, with degradation rate constants k: DH = 0.03142 min -1 RhB = 0.07137 min -1 Cr(VI) = 0.14245 min -1 This indicates that the composite of BaTiO3 and In2S3 can effectively improve photocatalytic efficiency, and also shows that heterojunctions are formed in the composite material BaTiO3 / In2S3. This result is consistent with the above photodegradation experiments.

[0070] like Figure 6 As shown, the BaTiO3 / In2S3 catalysts prepared in the examples and comparative examples were used for the degradation of Cr(VI), and the pollutant concentration changes were plotted. C t C0 and C0 represent the instantaneous and initial concentrations of the contaminant in the aqueous solution, respectively. From Figure 6 As can be seen, the Cr(VI) degradation rate of BaTiO3 / In2S3-(1:3) prepared using the example is 99%, while the Cr(VI) degradation rate of BaTiO3 / In2S3-(1:1) prepared using the comparative example is 85%. This demonstrates that the reduction effect of BaTiO3 / In2S3-(1:3) prepared using the example on Cr(VI) is better than that of BaTiO3 / In2S3-(1:1) prepared using the comparative example. In the example, the photocatalytic reduction ability was further enhanced by reasonably setting the ratio of BaTiO3 and In2S3.

[0071] like Figure 7 As shown, in order to investigate the kinetics of the BaTiO3 / In2S3 catalysts prepared in the examples and comparative examples on Cr(VI), the first-order kinetic equation ln(C) was used.t Simulation calculations are performed using / C0)=kt. Where C t C0 and C0 represent the instantaneous and initial concentrations of the pollutant in the aqueous solution, respectively. k represents the degradation rate constant. The reduction of Cr(VI) by the BaTiO3 / In2S3 catalyst follows a first-order kinetic model, with degradation rate constants k: BaTiO3 / In2S3 - (1:1) = 0.05972 min2. -1 ,BaTiO3 / In2S3-(1:3)=0.14245min -1 The BaTiO3 / In2S3-(1:3) prepared in the examples also showed a better rate of pollutant removal than the BaTiO3 / In2S3-(1:1) prepared in the comparative example.

[0072] like Figure 8 As shown, after three cycles of degradation experiments, the photocatalytic degradation activity of BaTiO3 / In2S3 prepared in the example for DH decreased slightly. XRD analysis of the BaTiO3 / In2S3 prepared in the example showed that the structure of BaTiO3 / In2S3 remained stable after photocatalytic degradation.

[0073] like Figure 9 As shown in (A), compared to BaTiO3 as an OSP (Optical Substructure Point), In2S3 as an RSP (Resilient Substructure Point) has a smaller work function and a higher Fermi level. When BaTiO3 and In2S3 come into contact and form a heterojunction, electrons will flow from In2S3, which has a higher Fermi level, to BaTiO3 to reach the equilibrium Fermi level, which generates a built-in electric field from In2S3 to BaTiO3. Figure 9 (B) Band bending occurs (In2S3 upwards and BaTiO3 downwards, respectively). It is noteworthy that there are four regions with different charge distribution densities in the heterojunction: the BaTiO3 bulk, the BaTiO3 interface, the In2S3 interface, and the In2S3 bulk. The built-in electric field (IEF) only acts on the interface and has no significant effect on the Fermi level of the deeper semiconductor layers. For example... Figure 9 (C) Upon irradiation, electrons in both semiconductors are photoexcited from VB to CB. Driven by the built-in electric field, bent band structure, and electrostatic repulsion, photogenerated electrons transfer from the CB of BaTiO3 to the VB of In2S3 to recombine with holes. Conversely, electrons in the CB of In2S3 and holes in the VB of BaTiO3 are transferred from the interior to the surface under the influence of IEF, bent band structure, and electrostatic repulsion. Thus, these electrons and holes available for redox reactions are spatially separated, and unwanted electrons and holes are eliminated, ensuring the system's high redox capacity.

[0074] The preparation method of BaTiO3 / In2S3 provided by this invention is simple, safe, and energy-efficient, with no toxic solvents involved, making it green and environmentally friendly. It demonstrates highly efficient photocatalytic degradation of doxycycline hydrochloride, degradation of rhodamine B, and reduction of Cr(VI), and its cost and photocatalytic efficiency have significant industrial application value.

[0075] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure, characterized in that, Includes the following steps: Step 1: Prepare carboxylated BaTiO3 nanoparticles using tetragonal BaTiO3; Step 2: After adding the carboxylated BaTiO3 nanoparticles, indium salt, C2H5NS and CH4N2O to distilled water, stir on a magnetic stirrer to obtain the first mixed solution; Step 3: Transfer the first mixed solution into an autoclave and heat it at 150℃~180℃ for 10h~12h to obtain the second mixed solution; Step 4: Cool the second mixed solution naturally to room temperature, and obtain the BaTiO3 / In2S3 heterojunction after washing, centrifugation, and drying. In step one, the method for preparing carboxylated BaTiO3 nanoparticles is as follows: Succinic anhydride was added to DMF and stirred to dissolve. Then, 3-aminopropyltriethoxysilane was added dropwise. The resulting mixture was stirred at room temperature, and then deionized water, DMF and BaTiO3 were added. After stirring at room temperature again, the mixture was washed three times with distilled water and ethanol respectively, and dried at 80 °C to obtain carboxylated BaTiO3 nanoparticles. In step two, the molar ratio of carboxylated BaTiO3 nanoparticles, InCl3·4H2O, C2H5NS, CH4N2O and distilled water is 17:100:200:200:

450.

2. The method for preparing core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure according to claim 1, characterized in that, In step two, the stirring speed is 500 rpm and the stirring time is 30 min.

3. The method for preparing core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure according to claim 2, characterized in that, The autoclave is a high-pressure autoclave with a polytetrafluoroethylene liner.

4. The method for preparing the core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure according to any one of claims 1-3, characterized in that, In step four, the product is washed three times with distilled water and ethanol, and then dried at 60 °C for 10 h to 12 h to obtain a BaTiO3 / In2S3 heterojunction.

5. A core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure, characterized in that, The core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure was prepared using the preparation method described in any one of claims 1-4.

6. The use of a core-shell nanoflower BaTiO3 / In2S3 heterojunction with S-shaped band structure, characterized in that, The core-shell nanoflower BaTiO3 / In2S3 heterojunction with an S-shaped band structure as described in claim 5 is used as a photocatalyst for the degradation of doxycycline hydrochloride, the degradation of rhodamine B, or the reduction of Cr(VI).

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