Strontium bismuth vanadium oxide photocatalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of photocatalysis, in particular to a strontium bismuth vanadium oxide photocatalyst and a preparation method and application thereof.The chemical formula of the photocatalyst is Sr3. 59Bi19.41 V4O42, the crystal structure of the photocatalyst belongs to an orthorhombic system, the space group of the photocatalyst is Immm, and the photocatalyst is of a unique layered structure composed of cation triple plate layers; the photocatalyst is synthesized by a molten salt method, and shows the activity of photocatalytic decomposition of water to produce oxygen under visible light. The preparation method comprises the following steps: mixing and grinding SrO, Bi2O3 and VO precursors with a molten salt medium, and then carrying out temperature programming calcination to synthesize a target product; the catalyst prepared by the method has the characteristics of high crystallinity, few defects and regular morphology, the photocatalytic oxygen production performance of the catalyst is remarkably superior to that of a same-component sample synthesized by a traditional solid-phase method, and photocatalytic water decomposition and oxygen production can be realized by taking a silver nitrate, ferric nitrate, ferric chloride or potassium ferricyanide aqueous solution as a sacrificial agent system under the irradiation of visible light with the wavelength of more than or equal to 420 nm.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis, specifically to a strontium bismuth vanadium oxide photocatalyst, its preparation method, and its application. Background Technology

[0002] Photocatalytic water splitting for hydrogen production is considered an ideal pathway to achieve a green energy revolution. The process mainly involves two half-reactions: hydrogen evolution and oxygen evolution. Kinetically, the oxygen evolution reaction, involving four-electron transfer, has a high energy barrier and a slow rate, and is considered the rate-determining step in the entire water splitting process. Therefore, developing efficient and stable photocatalytic oxygen production materials has become a core challenge in this field. Among numerous visible light-responsive materials, bismuth-based semiconductor materials (such as bismuth vanadate BiVO4) have shown significant potential in photocatalytic oxygen production due to their unique layered structure, suitable valence band position, and good visible light absorption capabilities, making them a research hotspot.

[0003] However, the actual performance of existing bismuth-based photocatalytic materials still falls far short of theoretical expectations. This bottleneck largely stems from the limitations of traditional material synthesis methods. Taking bismuth-based materials with complex stoichiometry as an example, the currently commonly used solid-state reaction method requires extremely high temperatures, which not only consumes a lot of energy but also easily leads to the loss of volatile components such as bismuth. This results in inherent defects such as deviations in stoichiometry, reduced crystallinity, impurity phase formation, and uncontrollable particle morphology and size. At the same time, the morphology is often disordered and aggregated, thus severely limiting the separation and transport efficiency of photogenerated carriers. These structural problems caused by synthesis methods, such as cation vacancy defects, interfacial recombination centers, and excessively long bulk charge migration paths, severely restrict the separation and transport efficiency of photogenerated carriers, becoming key obstacles to improving the intrinsic activity of materials.

[0004] In response to this situation, the molten salt method (Flux method), as an advanced crystal growth technique, provides a new solution for the preparation of high-quality bismuth-based catalysts. This method utilizes low-melting-point molten salt as the reaction medium, enabling efficient mass transfer and ordered atomic arrangement of reactants under relatively mild conditions. It effectively suppresses component deviation caused by volatilization, resulting in high-purity, high-crystallinity, and well-formed target products.

[0005] Based on this, the present invention innovatively synthesizes a novel bismuth-based composite metal oxide photocatalyst using the molten salt method. It is worth noting that the application of this photocatalyst in oxygen evolution has not been previously reported in the literature. This invention is the first to successfully synthesize this material using the molten salt method and confirm that it possesses certain intrinsic visible light-responsive photocatalytic oxygen evolution activity. This method not only overcomes the structural regulation bottleneck in traditional solid-phase synthesis but also provides a new material platform and synthetic route for exploring the application potential of this type of material in photocatalytic oxygen evolution. Summary of the Invention

[0006] This invention aims to provide a strontium bismuth vanadium oxide photocatalyst, its preparation method, and its application, by using SrO, Bi2O3, and After the precursor is mixed and ground with molten salt medium, the target product is synthesized by calcination under programmed temperature rise. The catalyst prepared by this method has the characteristics of high crystallinity, few defects and regular morphology. Its photocatalytic oxygen production performance is significantly better than that of the same component sample synthesized by traditional solid phase method. It can achieve photocatalytic water decomposition to produce oxygen under visible light with wavelength ≥420 nm, using silver nitrate, ferric nitrate, ferric chloride or potassium ferricyanide aqueous solution as sacrificial agent system.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a strontium bismuth vanadium oxide photocatalyst, wherein the chemical formula of the photocatalyst is [insert chemical formula here]. It possesses a unique layered crystal structure; the photocatalyst is synthesized via a molten salt method and exhibits photocatalytic water splitting and oxygen production activity under visible light; the strontium bismuth vanadium oxide photocatalyst belongs to the orthorhombic crystal system with space group [missing information]. Immm ,a = 11.6090(6) Å, b = 11.9678(6) Å, c = 16.2747(9) Å, V =2261.13(28) ų, α = β = γ = 90°;In an aqueous solution with silver nitrate as a sacrificial agent, the oxygen production of 100 mg photocatalyst sample was >2.62 mmol within 2 h.

[0008] Preferably, the photocatalyst has a regular crystal morphology and high crystallinity.

[0009] Preferably, the photocatalyst has light absorption capability under visible light irradiation with a wavelength ≥ 420 nm.

[0010] The above approach has the following beneficial effects: 1. This invention uses the molten salt method to synthesize Sr 3.59 Bi 19.41 V4O 42 The photocatalyst exhibits high crystallinity. Compared to the traditional solid-state method, the molten salt method, using a low-melting-point molten salt medium, promotes ordered atomic arrangement under mild conditions, effectively suppressing the loss of volatile components such as bismuth during high-temperature synthesis and avoiding stoichiometric deviations and impurity phase formation. The high crystallinity reduces internal defect states (such as cation vacancies), lowering the recombination probability of photogenerated carriers and thus improving charge separation efficiency. The reaction medium in the molten salt method promotes precise arrangement of lattice atoms, reducing lattice distortion and interface defects. Experiments show that the sample synthesized by the molten salt method exhibits a 2.05-fold improvement in oxygen evolution performance compared to the solid-state method, directly demonstrating the promoting effect of defect reduction on catalytic activity: defect reduction results in shorter transport paths for photogenerated electron-hole pairs and a lower recombination probability, thereby improving the kinetic efficiency of the oxygen evolution reaction.

[0011] 2. The catalyst synthesized by the molten salt method of this invention exhibits a uniform and ordered morphology, while the product from the solid-phase method is agglomerated and disordered. In the reaction, the molten salt medium regulates the ion diffusion rate, promoting crystal growth along specific crystal planes to form regular particles or layered structures. The ordered morphology increases the specific surface area of ​​the material, exposing more active sites (such as surface oxygen vacancies and unsaturated metal sites), providing more reaction sites for the oxygen evolution reaction. The synergistic effect of the ordered morphology and low-defect structure results in a more uniform distribution of active sites on the catalyst surface. Furthermore, because the material synthesized by the molten salt method has fewer surface defects and higher active site utilization, photogenerated holes can participate in the oxygen evolution reaction (four-electron transfer process) more efficiently, overcoming the problem of active site shielding caused by morphological agglomeration in traditional materials.

[0012] 3. The UV-Vis absorption spectrum of this invention shows that the catalyst exhibits significant absorption in the visible light region with wavelengths ≥420 nm, and its absorption edge extends to 461 nm in the visible light range. This material possesses a unique layered crystal structure (orthorhombic crystal system, space group 1). Immm By assigning it a suitable valence band position, it can effectively utilize visible light to generate charge carriers, thus broadening the scope of solar energy utilization. Compared with narrow bandgap materials, it is more adaptable to actual lighting conditions.

[0013] A method for preparing a strontium bismuth vanadium oxide photocatalyst includes the following steps: S1, Mixture preparation: with SrO, Bi2O3 and As a precursor, it is uniformly mixed with the molten salt medium; S2, molten salt synthesis: The precursor is mixed and ground with molten salt medium, then calcined in a muffle furnace by programmed temperature rise, cooled, cleaned and dried to obtain the photocatalyst.

[0014] Preferably, in S1, the precursor contains SrO, Bi2O3 and The molar ratio is 1.795:4.8525:1.

[0015] Preferably, in S1, the molten salt medium is one or more inorganic salts that are in a molten state at the reaction temperature and do not chemically react with the precursor.

[0016] Preferably, in S1, the ratio of the total mass of the selected molten salt medium to the theoretical yield of strontium bismuth vanadium oxide is in the range of 3:1 to 5:1.

[0017] Preferably, in S2, the calcination process is as follows: the temperature is increased from room temperature to 800°C at a rate of 5°C / min, the temperature is maintained for 10 hours, and then the furnace is cooled to room temperature.

[0018] Preferably, in S2, the cleaning method is: washing with deionized water 3 times; the drying conditions are: drying in an oven at 60°C overnight.

[0019] Beneficial effects

[0020] 1. Precursor SrO, and Strictly adhere to the molar ratio of 1.795:4.8525:1 for configuration. Ensure the final product Sr... 3.59 Bi 19.41 V4O 42 The chemical composition is consistent with theoretical expectations; The ratio of the total mass of the molten salt medium to the theoretical product mass is 3:1 to 5:1. This ratio has been experimentally verified as the optimal reaction medium concentration. The molten salt, acting as an "ion transport carrier," forms a low-viscosity liquid environment at 800℃, significantly reducing... , , The diffusion barrier of plasma promotes uniform mixing and orderly arrangement at the atomic level, thereby obtaining highly crystalline products. The liquid phase environment formed by excess molten salt confines the crystal growth space, inhibits agglomeration and disordered stacking during crystal growth, and promotes the formation of regular morphology of the material. Compared with the agglomerated particles of the solid phase method (without molten salt), the specific surface area is increased, exposing more catalytic active sites.

[0021] 2. The temperature is increased from room temperature to 800℃ at a low rate of 5℃ / min to avoid thermal stress damage caused by the rapid temperature rise in traditional solid-state methods. Slow heating allows the precursor to react fully with the molten salt, reducing lattice distortion caused by localized overheating and lowering the density of defects such as cation vacancies. The calcination temperature of 800℃ is significantly lower than that of traditional solid-state methods, thus suppressing… The volatilization (melting point 825℃) saves energy and ensures the thermodynamic conditions required for crystal growth, thus achieving "low-temperature and high-efficiency synthesis". Holding the catalyst at high temperature for 10 hours provides ample time for ion diffusion, promoting full lattice growth and forming a unique layered structure (with sharp XRD peaks and high crystallinity). Natural cooling within the furnace avoids internal stress caused by rapid cooling, further reducing defects and improving material stability. This process enables the oxygen production performance of the catalyst synthesized by the molten salt method to reach 2.05 times that of the solid-state method, directly demonstrating the decisive influence of crystallization quality on catalytic activity.

[0022] 3. Wash repeatedly with deionized water three times to completely remove the molten salt medium adhering to the catalyst surface by utilizing the high solubility of water in molten salt medium.

[0023] Drying at 60℃ overnight ensures complete evaporation of moisture without damaging the layered structure of the catalyst, providing a stable active surface for subsequent photocatalytic reactions.

[0024] An application of a strontium bismuth vanadium oxide photocatalyst is disclosed. The photocatalyst is used for the photocatalytic decomposition of water to produce oxygen. Under visible light irradiation, an aqueous solution of silver nitrate, ferric nitrate, ferric chloride, or potassium ferricyanide is used as a sacrificial agent system to achieve photocatalytic oxygen production.

[0025] Compared with the prior art, the beneficial effects of the present invention are: The photocatalytic oxygen production reaction of this invention, as a kinetically rate-determining step involving four-electron transfer, is highly dependent on the material's ability to separate and migrate photogenerated carriers. The catalyst synthesized by the molten salt method, due to its high crystallinity, low defect density, and regular morphology, effectively reduces the scattering and trapping centers of photogenerated carriers in the bulk phase, promoting efficient charge migration to the surface. Simultaneously, its regular microstructure shortens the physical path for charges to reach the reaction site. These structural advantages work together to significantly suppress electron-hole pair recombination, resulting in a significant improvement in charge separation efficiency compared to the solid-phase method sample. This is directly reflected in the fact that, in a reaction system using silver nitrate as a sacrificial agent, its photocatalytic oxygen production performance is 2.05 times that of the solid-phase method sample. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the method steps of the strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method and application embodiments; Figure 2 Sr is a strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method and application examples. 3.59 Bi 19.41 V4O 42 Schematic diagram of catalyst XRD pattern; Figure 3 Sr is a strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method and application examples. 3.59 Bi 19.41 V4O 42 Schematic diagram of EDS catalyst; Figure 4 Sr is a strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method and application examples. 3.59 Bi 19.41 V4O 42 Schematic diagram of the ultraviolet-visible absorption spectrum of the catalyst; Figure 5 Examples of Sr, bismuth, vanadium oxide photocatalysts, their preparation methods, and applications include the molten salt method and solid-phase method for synthesizing Sr. 3.59 Bi 19.41 V4O 42 A comparison diagram of facial features; Figure 6 This is a schematic diagram of the standard curve of oxygen production and peak area in the Shimadzu GC-2014C chromatography system, representing the strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method, and its application examples. Figure 7 This invention relates to Sr, a strontium bismuth vanadium oxide photocatalyst, its preparation method, and application examples. The Sr synthesized using solid-state and molten salt methods is described. 3.59 Bi 19.41 VO 42 A comparative diagram of catalyst performance; Figure 8 This invention relates to a strontium bismuth vanadium oxide photocatalyst, its preparation method, and its application examples. The Sr synthesized via the molten salt method (FLUX) is described. 3.59 Bi 19.41 V4O 42 Schematic diagram of the experimental results for the stability test of photocatalytic oxygen production; Figure 9 Sr is a strontium bismuth vanadium oxide photocatalyst of the present invention, its preparation method and application examples. 3.59 Bi 19.41 V 42 O 42 Schematic diagram of oxygen production by catalysts in different sacrificial agent systems for photocatalytic oxygen production. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A strontium bismuth vanadium oxide photocatalyst, the chemical formula of the photocatalyst being Sr 3.59 Bi 19.41 V4O 42 It possesses a unique layered structure; the photocatalyst is synthesized via a molten salt method and exhibits photocatalytic water splitting and oxygen production activity under visible light. In an aqueous solution using silver nitrate as a sacrificial agent, 100 mg of the photocatalyst sample produced >2.62 mmol of oxygen within 2 hours. The photocatalyst exhibits a regular crystal morphology and high crystallinity. It also demonstrates light absorption capability under visible light irradiation at wavelengths ≥420 nm.

[0030] Example 2

[0031] like Figure 1 As shown, the difference from Example 1 is that a method for preparing a strontium bismuth vanadium oxide photocatalyst, based on the strontium bismuth vanadium oxide photocatalyst described in Example 1, includes the following steps: S1, Mixture preparation: Using SrO, Bi2O3, and V2O5 as precursors, SrO and Bi2O3 are present in the precursors. and The molar ratio of NaCl to KCl is 1.795:4.8525:1; it is uniformly mixed with the molten salt medium. The molten salt medium is a mixture of NaCl and KCl, with a mass ratio of NaCl to KCl of 3.506:4.473. The ratio of the total mass of the molten salt medium to the theoretical yield of strontium bismuth vanadium oxide in the medium is 3:1. S2, molten salt synthesis: The precursor was mixed and ground with molten salt medium, and then calcined, cooled, cleaned and dried in a muffle furnace by programmed temperature rise. The calcination process was as follows: the temperature was raised from room temperature to 800℃ at a rate of 5℃ / min, and the reaction was held at that temperature for 10 hours, and then cooled to room temperature with the furnace. The cleaning method was: washing with deionized water 3 times. The drying conditions were: drying in an oven at 60℃ overnight. The photocatalyst was obtained.

[0032] The specific implementation process is as follows: Weigh out 186 mg SrO (1.795 mmol) and 2.26 g Bi2O3 (4.8525 mmol). As a reaction precursor, 3.506 g NaCl (60 mmol) and 4.473 g KCl (60 mmol) were added as a mixed molten salt medium (the ratio of the theoretical mass of the product to the total mass of the molten salt was approximately 1:3).

[0033] (2) After mixing the above raw materials evenly and grinding them thoroughly in a mortar, transfer them to a 50 ml corundum crucible and place them in a muffle furnace. The temperature is increased from room temperature to 800°C at a rate of 5°C / min. The reaction is kept at this temperature for 10 hours, and then the sample is allowed to cool naturally to room temperature with the furnace.

[0034] (3) Take out the sample and wash it three times with deionized water to remove residual sodium chloride and potassium chloride. Finally, dry it overnight in an oven at 60°C to obtain a light yellow powder Sr. 3.59 Bi 19.41 V4O 42 Photocatalyst. XRD such as Figure 2 As shown, EDS Figure 3 As shown, UV-Vis absorption is as follows Figure 4 As shown.

[0035] Samples prepared by the above molten salt method steps (such as...) Figure 5 (left) and solid-state method (such as) Figure 5(Right) Comparison of the morphology of the synthesized samples. During the solid-phase reaction, except for the absence of sodium chloride (NaCl) and potassium chloride (KCl), the raw materials remained consistent with the molten salt method. The calcination temperature was increased to 900℃ at a rate of 5℃ / min, and the reaction was held at this temperature for 10 hours. Afterwards, the sample was allowed to cool naturally to room temperature with the furnace. A yellow powder was finally obtained. SEM comparison of the catalysts synthesized by the two methods is shown below. Figure 5 As shown.

[0036] The concentration of oxygen-rich water produced during the reaction was determined using a standard curve of oxygen production versus peak area obtained from a Shimadzu GC-2014C chromatograph. The specific procedure is as follows: Preparation: Take 500 mL of oxygen into a gas sampling bag; confirm that the Shimadzu GC-2014C chromatograph and the Pofil mGAS1000 micro gas reaction evaluation system are working correctly.

[0037] Every half hour, oxygen of known concentration is injected into the Pofilai mGAS1000 micro gas reaction evaluation system. After the injected oxygen is thoroughly mixed, it is sent to the Shimadzu chromatograph for gas composition detection.

[0038] The oxygen concentration was calculated based on the measured peak areas of oxygen and nitrogen. The standard curve results are as follows: Figure 6 As shown.

[0039] In subsequent tests, the oxygen concentration of the sample was calculated based on the standard curve.

[0040] Sr synthesized by solid-state method (SSR) and molten salt method (FLUX) 3.59 Bi 19.41 V4O 42 Performance comparison.

[0041] The experimental preparation and testing methods were consistent with those in Example 3. Only silver nitrate was selected as the electron acceptor for performance testing. The oxygen production performance of the catalysts synthesized in both methods was tested, and the experimental results are as follows: Figure 7 As shown. Figure 7 The results show that, despite the differences between solid-state and molten salt methods in the synthesis of Sr 3.59 Bi 19.41 V4O 42All catalysts exhibit certain oxygen evolution performance under the same reaction conditions; however, catalysts synthesized via the molten salt method demonstrate superior oxygen evolution performance. For example, after 2 hours of illumination, 100 mg of the sample synthesized via the solid-state method produced 1.28 mmol of oxygen, while the sample synthesized via the molten salt method produced 2.62 mmol. Under the same 2-hour illumination period, the oxygen evolution of the sample synthesized via the molten salt method was 2.05 times that of the sample synthesized via the solid-state method. This performance improvement can be attributed to the molten salt method effectively improving the crystallinity of the material, reducing defects, and optimizing surface reaction sites, thereby significantly promoting photogenerated charge separation and transport efficiency and enhancing the catalytic oxygen evolution capability.

[0042] To test the synthesis of Sr by the molten salt method (FLUX) 3.59 Bi 19.41 V4O 42 The stability of photocatalytic oxygen production was assessed. The photocatalyst synthesized by the molten salt method described in Example 1 was used for the photocatalytic water splitting reaction to produce oxygen. Under visible light irradiation, with an aqueous solution of ferric nitrate as the sacrificial agent system, photocatalytic oxygen production was achieved.

[0043] Sr 3.59 Bi 19.41 V4O 42 The photocatalyst was used for stability testing of photocatalytic oxygen production. The specific process is as follows: (1) Take 100 mg Sr 3.59 Bi 19.41 V4O 42 The catalyst was dispersed in 100 mL of ferric nitrate aqueous solution (0.05 M), and the suspension was transferred to the reactor. It was then combined with the Pofilai mGAS1000 micro-gas reaction evaluation system, and vacuum treatment was performed for 45 minutes to completely remove dissolved air. A 300 W xenon lamp (PLS-SXE300 / 300UV, Pofilai) with a UV cutoff filter (λ ≥ 420 nm) provided visible light irradiation. The gases generated in the reaction were detected by an online gas chromatograph (GC-2014C, Shimadzu), equipped with a thermal conductivity detector and a 5 Å molecular sieve column, using high-purity argon as the carrier gas. The gas composition in the reactor was analyzed every half hour. Circulating cooling water was added throughout the reaction process to maintain the reaction temperature at approximately 15℃, and the reactor temperature at approximately 1℃. After each cycle, the sample in the reaction system was briefly centrifuged, washed, and redispersed in fresh Fe(NO3)3 solution to begin the next round of experiments. The experimental results are as follows: Figure 8 As shown.

[0044] (2) After 3 cycles, Sr 3.59 Bi 19.41 V4O 42The oxygen-producing activity of Sr did not decrease significantly. These results indicate that although the Fe³⁺ / Fe²⁺ redox relationship involves complex interfacial chemistry during cycling, Sr 3.59 Bi 19.41 V4O 42 It still exhibits excellent structural stability and catalytic durability.

[0045] Example 3

[0046] The difference from Example 2 is the application of a strontium bismuth vanadium oxide photocatalyst. The photocatalyst synthesized by the molten salt method as described in Example 1 is used for the photocatalytic water splitting to produce oxygen. Under visible light irradiation, an aqueous solution of silver nitrate or ferric nitrate is used as a sacrificial agent system to achieve photocatalytic oxygen production.

[0047] Sr 3.59 Bi 19.41 V4O 42 Photocatalysts are used for photocatalytic oxygen production, and the specific process is as follows: 100 mg Sr 3.59 Bi 19.41 V4O 42 The photocatalyst was dispersed in 100 mL of 0.005 M silver nitrate and 0.005 M ferric nitrate aqueous solutions. The suspension was transferred to the reactor and then combined with the Pofil mGAS1000 micro-gas reaction evaluation system. A vacuum treatment was performed for 45 minutes to completely remove dissolved air. A 300W xenon lamp (PLS-SXE300 / 300UV, Pofil) with a UV cutoff filter (≥420nm) provided visible light irradiation. The gases generated in the reaction were detected by an online gas chromatograph (GC-2014C, Shimadzu), equipped with a thermal conductivity detector and a 5Å molecular sieve column, using high-purity argon as the carrier gas. The gas composition in the reactor was analyzed every half hour. Circulating cooling water was added throughout the reaction process to maintain the reaction temperature at approximately 15℃, and the reactor temperature at approximately 1℃. Experimental results are as follows: Figure 9 .

[0048] Figure 9 The results in Sr 3.59 Bi 19.41 V4O 42 The catalyst exhibited certain oxygen production performance in both aqueous solutions using silver nitrate and ferric nitrate as sacrificial agents. However, it was clearly observed that the oxygen production performance was significantly higher with silver nitrate as the electron acceptor; 100 mg of the sample produced 2.62 mmol of oxygen in 2 hours, while the oxygen production with ferric nitrate as the electron acceptor was only 0.64 mmol in 2 hours.

[0049] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A strontium bismuth vanadium oxide photocatalyst, characterized in that, The chemical formula of the photocatalyst is It possesses a unique layered crystal structure; the photocatalyst is synthesized via a molten salt method and exhibits photocatalytic water splitting and oxygen production activity under visible light; the strontium bismuth vanadium oxide photocatalyst belongs to the orthorhombic crystal system with space group [missing information]. Immm ,a = 11.6090(6) Å, b = 11.9678(6) Å, c = 16.2747(9) Å, V = 2261.13(28) ų,α =β = γ = 90°;In an aqueous solution with silver nitrate as a sacrificial agent, the oxygen production of 100 mg photocatalyst sample within 2 h is >2.62 mmol.

2. The strontium bismuth vanadium oxide photocatalyst according to claim 1, characterized in that: The photocatalyst has a regular crystal morphology and high crystallinity.

3. The strontium bismuth vanadium oxide photocatalyst according to claim 1, characterized in that: The photocatalyst has light absorption capability under visible light irradiation with a wavelength ≥ 420 nm.

4. A method for preparing a strontium bismuth vanadium oxide photocatalyst, based on the strontium bismuth vanadium oxide photocatalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1, Mixture preparation: with SrO, Bi2O3 and As a precursor, it is uniformly mixed with the molten salt medium; S2, molten salt synthesis: The precursor is mixed and ground with molten salt medium, then calcined in a muffle furnace by programmed temperature rise, cooled, cleaned and dried to obtain the photocatalyst.

5. The method for preparing the strontium bismuth vanadium oxide photocatalyst according to claim 4, characterized in that: In S1, the precursors include SrO, Bi2O3, and The molar ratio is 1.795:4.8525:

1.

6. The method for preparing the strontium bismuth vanadium oxide photocatalyst according to claim 4, characterized in that: In S1, the molten salt medium is one or more inorganic salts that are in a molten state at the reaction temperature and do not chemically react with the precursor.

7. The method for preparing the strontium bismuth vanadium oxide photocatalyst according to claim 4, characterized in that: In S1, the ratio of the total mass of the selected molten salt medium to the theoretical yield of strontium bismuth vanadium oxide ranges from 3:1 to 5:

1.

8. The method for preparing the strontium bismuth vanadium oxide photocatalyst according to claim 4, characterized in that: In S2, the calcination process is as follows: the temperature is increased from room temperature to 800℃ at a rate of 5℃ / min, the reaction is held at this temperature for 10 hours, and then the furnace is cooled to room temperature.

9. The method for preparing the strontium bismuth vanadium oxide photocatalyst according to claim 4, characterized in that: In S2, the cleaning method is: wash 3 times with deionized water; the drying conditions are: dry overnight in an oven at 60℃.

10. An application of a strontium bismuth vanadium oxide photocatalyst, based on the strontium bismuth vanadium oxide photocatalyst and preparation method according to any one of claims 1 to 9, characterized in that, Photocatalysts are used for the photocatalytic splitting of water to produce oxygen. Under visible light irradiation, aqueous solutions of silver nitrate, ferric nitrate, ferric chloride, or potassium ferricyanide are used as sacrificial agents to achieve photocatalytic oxygen production.

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