Synthesis method and application of stannous niobate oxygen vacancy capable of being controlled and adjusted at low temperature

Abstract

The invention provides a synthesis method for low-temperature controllable adjustment of stannous niobate oxygen vacancy and application, and relates to the technical field of semiconductors. The synthesis method comprises the following steps: uniformly mixing niobium pentoxide and stannous chloride under an oxygen-free condition to obtain a solid-phase mixture, and carrying out molten salt reaction at 300-600 DEG C without an annealing step, so that the reaction product stannous niobate forms an oxygen vacancy and has a channel for rapid transmission of current carriers; according to the technical scheme, niobium oxide and stannous chloride are mixed in the reducing atmosphere to synthesize the high-crystallinity stannous niobate material with controllable oxygen vacancies at low temperature, the defect that high-performance stannous niobate must be subjected to a high-temperature annealing process is overcome, and meanwhile, by controlling the gas flow rate in the reaction process, the high-crystallinity stannous niobate material with controllable oxygen vacancies can be obtained. The aim of controlling and adjusting the quantity of oxygen vacancies under a relatively mild low-temperature condition to control and synthesize stannous niobate materials with different properties is fulfilled by reaction parameters such as a reactant ratio and the like.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and specifically to a method for synthesizing and applying stannous niobate with low-temperature controllable oxygen vacancies. Background Technology

[0002] The development of the economy and industrial technology requires high energy consumption, which contradicts the depletion of fossil fuel reserves and is accompanied by serious environmental problems. Therefore, renewable and clean energy is an important pillar for future sustainable economic development. Hydrogen, as a high-energy-density gas, can extract reaction products from water and is pollution-free, possessing enormous development potential. Photocatalysis and photoelectrocatalytic water splitting are technologies that use sunlight to generate electron-hole pairs in semiconductors for the reduction and oxidation of water into hydrogen and oxygen. Semiconductors play a crucial role. Stannous niobate has suitable bandwidth and band edge positions, with almost the same bandwidth as bismuth vanadate, but its valence band position is at -0.25 eV, giving it the potential for complete water splitting. It also has the same theoretical photocurrent density as bismuth vanadate, making stannous niobate a promising photoanode material. Existing technologies have reported photocurrent densities of up to 1 mA / cm². 2 (1.23V vs. RHE), however, current research mainly focuses on loading different protective layers, catalysts, or combining with other cathode materials to form junctions or Z-scheme structures on the surface. The research and development of the intrinsic photoelectric properties of the material still faces considerable difficulties. The main reason is that the photoelectric properties of the material depend on the crystallinity of the semiconductor material, the internal carrier concentration, and the surface properties of the material. Higher crystallinity of the semiconductor material can reduce the resistance to the transport of photogenerated carriers inside the semiconductor, thereby reducing the recombination of carriers at bulk defects. Higher internal carrier concentration can also reduce the material resistance, making it easier for charge to be transported. The surface may recombine due to heteroatoms or lattice defects, or there may be insufficient reactive centers, leading to charge accumulation on the surface and causing damage to the material itself. The complex relationship between these factors hinders the research of stannous niobate, which is fraught with difficulties.

[0003] On the other hand, stannous niobate has a suitable band gap and band position for photoelectrochemical hydrogen production, with the potential for full water splitting and a theoretical photocurrent of 7.7 mA. This makes stannous niobate itself a highly promising material for photoelectrochemical water splitting. However, its photoelectrochemical performance is still at a low level. The photocurrent value of actual products is far lower than its theoretical photocurrent value. The reason for this is that stannous niobate materials with high crystallinity and high carrier concentration cannot be obtained.

[0004] Traditional synthesis of tin niobate (SnNb₂O₆) involves raw materials, most of which are niobium compounds with poor solubility in acidic and alkaline solutions. At lower reaction temperatures, the activation energy of the raw materials is low. Furthermore, due to the instability of Sn(II), Sn is inevitably oxidized to tetravalent Sn(IV) during the traditional wet reaction process. This results in tetravalent Sn(IV) occupying Nb(V) positions in the prepared tin niobate (SnNb₂O₆), creating hole compensation and giving SnNb₂O₆ a p-type characteristic. Moreover, tin niobate obtained at low temperatures tends to form an incomplete core-shell structure, resulting in poor crystallinity, high bulk resistivity, and internal defects that can form electron-hole recombination centers, reducing the photoelectrocatalytic activity of tin niobate.

[0005] Chinese invention patent CN111348683A discloses a solid-state method for synthesizing highly crystalline tin niobate. The method involves a solid-state mixture of niobium pentoxide and stannous chloride undergoing a molten salt reaction at high temperatures. Specifically, the reaction is carried out at 350–600°C for 3–20 hours, followed by annealing at 750–1100°C for 5–20 hours to obtain highly crystalline tin niobate. The high-temperature conditions provide the raw materials with higher activation energy, which is beneficial for the lattice reconstruction of niobium pentoxide and stannous chloride to synthesize oxygen-rich, highly crystalline tin niobate, reducing defects caused by poor crystallinity. This results in high crystallinity and improved photoelectrocatalytic activity. However, the improvement in carrier concentration remains unsatisfactory.

[0006] Based on this, the present invention provides a method for synthesizing stannous niobate with controllable low-temperature oxygen vacancies, which ensures both high crystallinity and high carrier concentration in the stannous niobate optoelectronic material. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method and application for the synthesis of stannous niobate with controllable low-temperature vacancy regulation, which combines the characteristics of high crystallinity and high carrier concentration, and also has the advantages of mild reaction conditions, simple process, and low cost.

[0008] To achieve the above objectives, this invention provides a low-temperature controllable synthesis method for stannous niobate with adjustable oxygen vacancies. A solid mixture of niobium pentoxide and stannous chloride, homogenized under anaerobic conditions, is subjected to a molten salt reaction at 300–600°C without an annealing step. This allows the reaction product, stannous niobate, to form oxygen vacancies, resulting in a higher carrier concentration. The heating and cooling rates are adjustable within the range of 1–20°C / min, with different rates indicating different heating times within different temperature ranges. The gas flow rate is controlled between 10–600 mL / min.

[0009] In this invention, niobium pentoxide and stannous chloride can synthesize highly crystalline stannous niobate at low temperatures, and the internal oxygen vacancy concentration can be controlled. The lower temperature reduces equipment pressure and lowers the threshold for industrialization. The high crystallinity reduces the recombination of charges at defect sites inside the material, promotes the transport of charges from the inside to the surface for further reaction, and the controllable oxygen defect content indirectly controls the carrier concentration inside the material, thereby reducing the material resistance, changing the internal recombination mode of the material, and increasing its performance, providing a reasonable means for further optimizing its performance.

[0010] Preferably, the atomic molar ratio of niobium to tin in the solid mixture is 0.4 to 20:1, that is, tin and niobium are in equal or excess amounts to meet thermodynamic requirements.

[0011] Preferably, the amount of stannous chloride added is excessive.

[0012] Preferably, the molten salt reaction conditions include a temperature of 300~600℃, a reaction time of 2~48h, and a heating rate of 1℃ / min~20℃ / min.

[0013] The mechanism of molten salt reaction is as follows: ; Preferably, the molten salt reaction is carried out in a flowing atmosphere; the flow rate of the flowing atmosphere is 10~600 mL / min.

[0014] Preferably, the reaction conditions for the molten salt reaction are reduction conditions; the reduction conditions include being carried out under a reducing atmosphere.

[0015] Preferably, the reducing atmosphere comprises a mixture of hydrogen and an inert gas.

[0016] Preferably, the inert gas includes either argon or nitrogen.

[0017] Preferably, the product obtained from the molten salt reaction is soaked in acid to remove excess stannous chloride, rinsed with plenty of water until neutral, dried, and stored in an inert gas atmosphere.

[0018] Stannous niobate was prepared by a low-temperature controllable method for adjusting oxygen vacancies in stannous niobate based on the above technical solution.

[0019] The technical solution of this invention enables the control of oxygen defects during the synthesis process at low temperatures. Furthermore, the oxygen defects generated during synthesis can be controlled by adjusting reaction conditions or process parameters, thereby promoting the application of stannous niobate in photocatalysis and photoelectrocatalysis. In particular, the low-temperature synthesis of highly crystalline stannous niobate materials with controllable oxygen vacancies under a reducing atmosphere overcomes the drawback of requiring high-temperature annealing for highly crystalline materials, and allows for the controllable acquisition of stannous niobate materials with different properties.

[0020] The beneficial technical effects obtained by this invention are as follows: 1. The technical solution of this invention involves thoroughly mixing and grinding niobium pentoxide and stannous chloride at an Nb / Sn atomic molar ratio of 0.42-20 for 10 minutes to 2 hours until completely homogeneous. Then, the mixture is placed in a quartz boat and synthesized at a low temperature (300-600°C) in an inert or hydrogen-reducing atmosphere in a tube furnace. This process overcomes the drawback of requiring high-temperature annealing for highly crystalline materials and allows for the controllable generation of oxygen vacancies, resulting in stannous niobate materials with different properties. The reaction was carried out at a gas flow rate in the range of 10 mL / min to 600 mL / min, which achieved the goal of controlling the amount of oxygen vacancies to synthesize stannous niobate materials with different properties under relatively mild low temperature conditions.

[0021] 2. Using the technical solution of this invention, stannous niobate with different oxygen vacancies can be synthesized controllably by a low-temperature solid-state method. In particular, as the number of oxygen vacancies increases, the carrier concentration increases, thereby obtaining stannous niobate optoelectronic materials with different carrier concentrations.

[0022] 3. By adopting the technical solution of the present invention, stannous niobate with different carrier concentrations can be obtained by molten salt reaction through a single low-temperature calcination, without the need for high-temperature annealing, reducing process steps and process difficulty. The reaction conditions of this method are milder than those of the prior art, which greatly reduces manufacturing costs and process difficulty, and provides a technical and economic foundation for future industrialization and application promotion. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of stannous niobate prepared in Example 1 of the present invention.

[0024] Figure 2 The image shows the XRD pattern of stannous niobate prepared in Example 1 of this invention.

[0025] Figure 3 The images show the EPR diagrams of stannous niobate prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0026] Figure 4 The images show the Mott-Schottky diagrams of stannous niobate prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0027] Figure 5 The image shows a comparison of the photocurrent-voltage curves of the stannous niobate obtained in Examples 1-3 and Comparative Example 1 of this invention.

[0028] Figure 6The image shows a comparison of the photocurrent-voltage curves of stannous niobate prepared in Examples 4-7 of this invention. Detailed Implementation

[0029] In view of the deficiencies of the prior art, this invention proposes a method for controllably synthesizing stannous niobate materials with different oxygen vacancies at a relatively low temperature. The specific technical solution of this invention is described in detail below through specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. For the sake of brevity, this specification cannot provide a detailed description of all features of the actual embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] It should be noted that, unless otherwise defined, the technical or scientific terms used in this specification should be known to those skilled in the art described in this application.

[0031] This invention provides a method for the controllable synthesis of stannous niobate with different oxygen vacancies. A solid mixture of niobium pentoxide and stannous chloride, homogenized under oxygen-free conditions, is subjected to a molten salt reaction at 300-600°C without annealing. This process creates oxygen vacancies in the resulting stannous niobate, providing channels for rapid carrier transport. In this invention, highly crystalline stannous niobate can be synthesized from niobium pentoxide and stannous chloride at low temperatures, and the internal oxygen vacancy concentration can be controlled. The lower temperature reduces equipment stress, lowering the barrier to industrialization. The high crystallinity reduces charge recombination at defect sites within the material, promoting charge transport from the interior to the surface for further reaction. The controllable oxygen defect content indirectly controls the carrier concentration within the material, thereby reducing material resistance, altering the internal recombination pattern, and enhancing performance. This provides a reasonable means to further optimize its performance.

[0032] Preferably, the atomic molar ratio of niobium to tin is 0.42 to 20:1.

[0033] Preferably, the amount of stannous chloride is greater than or equal to the amount of niobium pentoxide to ensure a more complete reaction.

[0034] The technical effects of the present invention will be described in detail below through specific embodiments.

[0035] Example 1 Weigh 1.5g of niobium pentoxide and 3g of stannous chloride and grind them for 30min under an inert atmosphere until a homogeneous mixture is formed. Transfer the mixture to a quartz boat and then to a tube furnace. Introduce a mixture of argon and hydrogen with a volume ratio of 19:1 and a flow rate of 100mL / min. Heat the mixture to 500℃ at a heating / cooling rate of 1℃ / min and react for 8h. The resulting yellow powder is washed with 3M hydrochloric acid, diluted with a large amount of deionized water to neutralize it, and then filtered to obtain the yellow powder.

[0036] The powder was dried in a vacuum oven at 60°C for 6 hours to obtain powder for subsequent physical and photoelectrochemical tests.

[0037] See Figure 1 Here is a SEM image of the stannous niobate prepared in this embodiment, see reference. Figure 2 The image shows the XRD pattern of stannous niobate prepared in this embodiment. The figure illustrates that the method of the present invention can synthesize highly crystalline stannous niobate sheet material.

[0038] Example 2 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 1.5g of niobium pentoxide and 3g of stannous chloride were weighed and ground for 30 minutes under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. A mixture of argon and hydrogen was introduced, with a volume ratio of 19:1 and a flow rate of 150 mL / min. The temperature was increased to 500℃ at a heating / cooling rate of 1℃ / min and reacted for 8 hours. The resulting yellow powder was washed with 3M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60℃ for 6 hours. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0039] Example 3 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 1.5 g of niobium pentoxide and 3 g of stannous chloride were weighed and ground for 30 min under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. An argon-hydrogen mixture was introduced at a flow rate of 200 mL / min, and the temperature was increased to 500 °C at a heating / cooling rate of 1 °C / min for 8 h. The resulting yellow powder was washed with 3 M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60 °C for 6 h. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0040] Example 4 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 2g of niobium pentoxide and 1.1g of stannous chloride were weighed and ground for 50min under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. An argon-hydrogen mixture was introduced at a flow rate of 400mL / min, and the temperature was raised to 550℃ at a heating and cooling rate of 4℃ / min for 20h. The resulting yellow powder was washed with 3M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60℃ for 6h. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0041] Example 5 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 1.2 g of niobium pentoxide and 1.71 g of stannous chloride were weighed and ground for 50 min under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. Argon gas was introduced at a flow rate of 400 mL / min, and the temperature was increased to 300 °C at a heating and cooling rate of 4 °C / min for 3 h. The resulting yellow powder was washed with 3 M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60 °C for 6 h. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0042] Example 6 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 1.5 g of niobium pentoxide and 2.13 g of stannous chloride were weighed and ground for 50 min under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. An argon-hydrogen mixture was introduced at a flow rate of 400 mL / min, and the temperature was raised to 400 °C at a heating / cooling rate of 4 °C / min for 2 h. The resulting yellow powder was washed with 3 M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60 °C for 6 h. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0043] Example 7 This embodiment provides a method for controllably synthesizing stannous niobate with different oxygen vacancies, the specific steps of which include: 1 g of niobium pentoxide and 2.85 g of stannous chloride were weighed and ground for 50 min under an inert atmosphere until a homogeneous mixture was formed. The mixture was then transferred to a quartz boat and further transferred to a tube furnace. An argon-hydrogen mixture was introduced at a flow rate of 400 mL / min, and the temperature was increased to 300 °C at a heating / cooling rate of 4 °C / min. The resulting yellow powder was washed with 3 M hydrochloric acid and then diluted with a large amount of deionized water to neutralize it. The yellow powder was filtered and dried in a vacuum oven at 60 °C for 6 h. The powder was then subjected to subsequent physical property and photoelectrochemical tests.

[0044] See Figure 6 The figures show the photocurrent-voltage curves of stannous niobate prepared in Examples 4-7, respectively. As can be seen from the figure, the carrier concentration in Example 6 is the highest, which is higher than that in the other examples. In Example 4, stannous niobate was prepared by reacting niobium and tin in an atomic molar ratio of 1:0.42 (equivalent).

[0045] Comparative Example 1 This embodiment provides a method for the controllable synthesis of stannous niobate with different oxygen vacancies. The specific steps include: weighing 1.5g of niobium pentoxide and 0.85g of stannous chloride and grinding them under an inert atmosphere (argon) for 30min to form a homogeneous solid mixture, transferring it to a quartz boat, and then further transferring it to a tube furnace and introducing argon at a flow rate of 100mL / min. The temperature is increased to 500℃ at a heating and cooling rate of 1℃ / min and reacted for 8h. The resulting yellow powder is washed with 3M hydrochloric acid, diluted with a large amount of deionized water to neutralize it, and filtered to obtain the yellow powder.

[0046] The yellow powder was dried in a vacuum oven at 60°C for 6 hours before subsequent physical and photoelectrochemical performance tests were conducted.

[0047] See Figure 3 The figure shows the EPR (Enhanced Permeability) curves of stannous niobate prepared in Comparative Example 1 and Examples 1, 2, and 3. In the figure, the oxygen vacancy content is characterized by EPR, where the g-value represents an oxygen vacancy of 2.004; and the relative intensity represents the oxygen vacancy content. As can be seen from the figure, under the same conditions, the relative intensity is very low when only argon gas is introduced. However, when 5% hydrogen gas is present, the relative intensity increases with the increase of gas flow rate, indicating an increase in oxygen vacancy. Clearly, controlling the gas flow rate allows for the synthesis of stannous niobate with different oxygen vacancy levels.

[0048] See Figure 4 The figures show the Mott-Schottky plots of stannous niobate prepared in Examples 1-3 and Comparative Example 1, respectively. The slope of the Mott-Schottky plot represents the relative magnitude of the internal carrier concentration; a larger slope indicates a lower carrier concentration, and vice versa. As can be seen from the figures, when the reducing gas contains 5% hydrogen, the carrier concentration increases with the increase of the gas flow rate.

[0049] See Figure 5 The photocurrent-voltage curves of stannous niobate prepared in Examples 2-4 and Comparative Example 1 are shown.

[0050] Furthermore, through Figure 3 , Figure 4 and Figure 5The characterization comparison diagrams of oxygen vacancy content and carrier concentration of stannous niobate prepared in Examples 2-4 and Comparative Example 1 show that, only under oxygen-deficient conditions without hydrogen doping (Ar2, 100 mL / min), the EPR signal is smaller and the Mott-Schottky slope is the largest compared to the reducing gas doped with hydrogen. This indicates that the bulk oxygen vacancy and carrier concentration of stannous niobate prepared in this comparative example are much smaller than those in Examples 2-4, and also indicates that the photocurrent response of the stannous niobate material is the worst.

[0051] Comparative Example 2 This comparative example provides a method for the controllable synthesis of stannous niobate with different oxygen vacancies, the specific steps of which include: Weigh 1.5g of niobium pentoxide and 0.85g of stannous chloride and grind them for 10min under an inert atmosphere until a homogeneous mixture is formed. Transfer the mixture to a quartz boat and then to a tube furnace. Introduce an argon-hydrogen mixture at a flow rate of 20mL / min and heat it to 300℃ at a heating and cooling rate of 4℃ / min. React for 48h to obtain a white powder.

[0052] The white powder was washed with 3M hydrochloric acid, then diluted with a large amount of deionized water to neutral, filtered, and dried in a vacuum oven at 60°C for 6 hours.

[0053] The stannous niobate prepared in this comparative example has a different color from the products obtained in Examples 1-7, indicating a higher impurity content. Clearly, by employing the technical solution of this invention, under a reducing gas atmosphere and high temperature conditions, the higher activation energy of the reactants promotes the lattice reconstruction of niobium pentoxide and stannous chloride to synthesize oxygen-rich, highly crystalline stannous niobate, reducing defects caused by poor crystallinity. Furthermore, the resulting stannous niobate product not only has high crystallinity but also significantly increased carrier concentration, enhancing photoelectrocatalytic activity and solving the technical problems existing in the prior art.

[0054] In summary, this invention enables the controllable synthesis of stannous niobate with different oxygen vacancies via a low-temperature solid-state method. In particular, the carrier concentration increases with the increase of oxygen vacancies, thereby obtaining stannous niobate optoelectronic materials with different carrier concentrations. Moreover, the preparation process is simple, requiring only a single low-temperature calcination molten salt reaction to obtain stannous niobate with different carrier concentrations, eliminating the need for high-temperature annealing, reducing process steps, and significantly lowering the process difficulty. The reaction conditions of this method are milder than existing technologies, greatly reducing manufacturing costs and process difficulty, and providing a technical and economic foundation for future industrialization and application promotion.

[0055] In addition, the inventors of this case also conducted corresponding experiments using other raw materials and process conditions listed above as alternatives to the various raw materials and corresponding process conditions of the embodiments. The obtained stannous niobate material has high crystallinity and strong photocatalytic activity, and is basically similar to the stannous niobate product prepared in the embodiments.

[0056] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A method for synthesizing stannous niobate with low-temperature controllable oxygen vacancies, wherein a solid mixture of niobium pentoxide and stannous chloride is uniformly mixed under anaerobic conditions and then subjected to a molten salt reaction at a temperature of 300~600℃ without an annealing step, so that the reaction product stannous niobate forms oxygen vacancies and has channels for rapid carrier transport.

2. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 1, characterized in that, The atomic molar ratio of niobium to tin in the solid mixture is 0.42 to 20:

1.

3. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 1, characterized in that, The molten salt reaction conditions include a temperature of 300~600℃, a reaction time of 2~48h, and a heating rate of 1℃ / min~20℃ / min.

4. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 1, characterized in that, The molten salt reaction is carried out in a flowing atmosphere; the flow rate of the flowing atmosphere is 10~600 mL / min.

5. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 1, characterized in that, The reaction conditions for the molten salt reaction are reduction conditions, which include being carried out under a reducing atmosphere.

6. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 5, characterized in that, The reducing atmosphere is a mixture of hydrogen and an inert gas.

7. The method for synthesizing stannous niobate with controllable low-temperature regulation of oxygen vacancies according to claim 6, characterized in that, The inert gas includes either argon or nitrogen. The volume ratio of hydrogen to inert gas in the reducing atmosphere is 1:

19.

8. The method for synthesizing stannous niobate with low-temperature controllable adjustment of oxygen vacancies according to any one of claims 1-7, characterized in that, It also includes washing the product obtained from the molten salt reaction with acid until neutral, drying it, and storing it in an inert gas.

9. Stannous niobate prepared by the low-temperature controllable adjustment of oxygen vacancies in stannous niobate synthesis method according to any one of claims 1-8.

10. The application of stannous niobate according to claim 9 in the fields of photocatalysis and photoelectrocatalysis.

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