TiN-Fe2O3 heterostructure catalyst, preparation method thereof and lithium oxygen battery

Abstract

The invention belongs to the field of lithium-air batteries, and provides a TiN-Fe2O3 heterostructure catalyst, a preparation method thereof and a lithium-oxygen battery. The TiN-Fe2O3 heterostructure catalyst comprises an inner core and a shell located on at least part of the surface of the inner core, the contact interface of the inner core and the shell is a heterojunction interface, the inner core comprises titanium nitride, and the shell comprises ferric oxide. According to the TiN-Fe2O3 heterostructure catalyst disclosed by the embodiment of the invention, based on the existence of the heterojunction between the titanium nitride and the ferric oxide, the separation rate of photo-induced electrons-holes can be effectively improved, so that the electrode reaction kinetics of a battery containing the TiN-Fe2O3 heterostructure catalyst is effectively improved.

Description

Technical Field

[0001] This application relates to the field of lithium-oxygen battery technology, and in particular to a TiN-Fe2O3 heterostructure catalyst and its preparation method, and a lithium-oxygen battery. Background Technology

[0002] Against the backdrop of the accelerated global energy structure transition towards low-carbonization, the development of energy storage technologies with high energy density and high efficiency is particularly urgent. Lithium-oxygen batteries, due to their extremely high theoretical specific capacity (3862 mAh g⁻¹), are a promising candidate. - ¹) It is considered a strong candidate for the next generation of energy storage systems. However, the development of this system faces significant challenges: First, the insulating properties of the discharge product lithium peroxide (Li2O2) result in a charging voltage that is usually as high as 4.2-4.5V; Second, the slow oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics on the air cathode together limit its practical application potential.

[0003] Titanium nitride, as the cathode material of photo-assisted lithium-oxygen batteries, possesses a noble metal-like electronic structure and high conductivity, which facilitates rapid charge transport. As a bifunctional catalyst, it enhances the kinetics of oxygen reduction (ORR) and oxygen evolution (OER). In addition, titanium nitride can absorb light energy in a wide range from visible to near-infrared light and increases the reaction interface temperature through localized surface plasmon resonance (LSPR) and photothermal effects, thereby promoting the decomposition of lithium peroxide.

[0004] The electron-hole pairs generated by titanium nitride under photoexcitation recombine rapidly, failing to effectively participate in the electrochemical reaction and limiting its effect on improving reaction kinetics. Its poor photocatalytic performance also restricts its application in all scenarios. Therefore, there is an urgent need to develop an effective method for synthesizing high-performance photo-assisted lithium-air battery heterostructure catalysts.

[0005] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of protection of this application. Summary of the Invention

[0006] This application provides a TiN-Fe2O3 heterostructure catalyst and its preparation method, as well as a lithium-oxygen battery, to solve or alleviate one or more of the technical problems mentioned above.

[0007] A first aspect of this application provides a TiN-Fe2O3 heterostructure catalyst, comprising a core and a shell located on at least a portion of the surface of the core, wherein the contact interface between the core and the shell is a heterojunction interface, the core comprising titanium nitride, and the shell comprising ferric oxide.

[0008] The presence of a heterojunction between titanium nitride and ferric oxide in the TiN-Fe2O3 heterostructure catalyst of this application embodiment can effectively improve the separation rate of photogenerated electrons and holes, thereby effectively improving the electrode reaction kinetics of the battery containing the TiN-Fe2O3 heterostructure catalyst.

[0009] Specifically, the shell structure enables the formation of a large-area, dense heterojunction interface between TiN and Fe2O3. This interface facilitates the formation of a strong built-in electric field between the core and the shell. When the Fe2O3 shell is photoexcited to generate electron-hole pairs, the built-in electric field drives photogenerated electrons to rapidly transfer from the conduction band of Fe2O3 to the TiN core, while retaining holes in the Fe2O3 shell. This achieves highly efficient spatial separation of photogenerated carriers, greatly suppressing recombination and improving charge separation efficiency. Using highly conductive TiN as the core provides a rapid conduction network for electrons injected from the Fe2O3 shell. Electrons can migrate at high speed in the TiN core, similar to their speed in metals, and are quickly transported to current collectors or reactive sites, effectively overcoming the bottleneck of poor conductivity in Fe2O3 itself and significantly accelerating the charge transfer process of the electrode reaction. When this TiN-Fe2O3 heterostructure catalyst is used as the cathode in a lithium-oxygen battery, the Fe2O3 shell is directly exposed to the electrolyte or reaction atmosphere. Its surface can serve as an active site for the catalytic reaction, which is beneficial for the oxygen reduction / evolution reaction. This results in better structural stability and durability during long-term electrochemical reactions or photoelectric cycles. During discharge, the TiN core rapidly conducts electrons to promote O2 reduction; during charging, the Fe2O3 shell accumulates holes to efficiently decompose Li2O2. Under light-assisted illumination, the injection of photogenerated carriers can further reduce the battery's charge-discharge polarization, improving energy efficiency and cycle life.

[0010] According to the embodiments of this application, the TiN mass percentage is 70%-80% based on the total mass of the TiN-Fe2O3 heterostructure catalyst.

[0011] According to an embodiment of this application, the particle size of the core is 150nm-300nm; the thickness of the shell is 20nm-70nm.

[0012] A second aspect of this application provides a method for preparing a TiN-Fe2O3 heterostructure catalyst, comprising the following steps: The fabric containing titanium dioxide seed crystals was placed in a first tetrabutyl titanate solution for reaction treatment. The product obtained from the reaction treatment was subjected to nitriding with melamine to obtain titanium nitride nanorods; The titanium nitride nanorods, iron salt solution, and morphology control agent were mixed to obtain a TiN-Fe2O3 heterostructure catalyst.

[0013] The method of this application embodiment involves reacting a fabric containing titanium dioxide seeds in a first tetrabutyl titanate solution to obtain a titanium dioxide array on the fabric; then, the result of the reaction treatment is nitrided with melamine to obtain titanium nitride nanorods; the titanium nitride nanorods, an iron salt solution, and a morphology control agent are mixed. During this mixing process, the iron salt hydrolyzes to form ferric oxide, which adheres to the surface of the titanium nitride nanorods, and the morphology control agent selectively adsorbs onto specific crystal faces of the ferric oxide crystals, inhibiting the growth rate of those crystal faces, thereby causing the crystals to preferentially grow along a certain direction (such as the c-axis). This results in a TiN-Fe2O3 heterostructure catalyst with a needle-like array. Furthermore, this method is simple and easy to implement. By controlling the reaction conditions, a TiN-Fe2O3 heterostructure catalyst is obtained. Based on the presence of the heterojunction between titanium nitride and ferric oxide, it can effectively improve the separation rate of photogenerated electrons and holes, thereby effectively improving the electrode reaction kinetics of the battery containing this TiN-Fe2O3 heterostructure catalyst.

[0014] According to an embodiment of this application, the method of forming the fabric with titanium dioxide seed crystals includes: providing a fabric and pre-oxidizing the fabric; placing the pre-oxidized product in a second tetrabutyl titanate solution to obtain the fabric with titanium dioxide seed crystals.

[0015] According to an embodiment of this application, the fabric comprises carbon cloth.

[0016] According to an embodiment of this application, the pre-oxidation temperature is 300℃-500℃ and the time is 0.5h-2h.

[0017] According to an embodiment of this application, the second tetrabutyl titanate solution comprises isopropanol and tetrabutyl titanate.

[0018] According to an embodiment of this application, the concentration of tetrabutyl titanate in the second tetrabutyl titanate solution is 0.7 mol / L-0.9 mol / L.

[0019] According to an embodiment of this application, the first tetrabutyl titanate solution comprises hydrochloric acid, tetrabutyl titanate, and water, wherein the volume ratio of hydrochloric acid, tetrabutyl titanate, and water is 1:(0.01-0.1):(0.5-2); the reaction time is 8h-15h, and the temperature is 100℃-200℃; the nitriding treatment is carried out in an inert atmosphere, with the temperature increased to 700℃-900℃ at a heating rate of 3℃ / min-6℃ / min and held for 1h-3h.

[0020] According to an embodiment of this application, the mass ratio of the titanium nitride nanorods, the iron salt, and the morphology control agent during the mixing process is 1:(1-2):(3-8).

[0021] According to embodiments of this application, the iron salt in the mixing process includes at least one of ferric chloride, ferric sulfate, and ferric nitrate.

[0022] According to embodiments of this application, the morphology control agent during the mixing process includes at least one of sodium sulfate.

[0023] According to an embodiment of this application, the temperature during the mixing process is 100℃-150℃, and the time is 1h-6h.

[0024] According to a third aspect of this application, a lithium-oxygen battery is provided, including a positive electrode sheet, wherein the positive electrode sheet includes a positive electrode active material layer, and the positive electrode active material layer includes the TiN-Fe2O3 heterostructure catalyst described in the first aspect or the TiN-Fe2O3 heterostructure catalyst prepared by the preparation method described in the second aspect.

[0025] According to an embodiment of this application, the lithium-oxygen battery further includes a negative electrode and an electrolyte. The negative electrode is a lithium metal sheet, and the electrolyte includes an electrolyte and a solvent. The electrolyte includes lithium trifluoromethanesulfonate, and the solvent includes tetraethylene glycol dimethyl ether. The concentration of the electrolyte in the electrolyte is 0.5 mol / L to 2 mol / L. Attached Figure Description

[0026] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0027] Figure 1 This is a schematic diagram of the preparation process of TiN-Fe2O3 heterostructure catalysts in some embodiments; Figure 2 This is a scanning electron microscope image of the TiN-Fe2O3 heterostructure catalyst from Example 1; Figure 3 This is a scanning electron microscope image of the TiN-Fe2O3 heterostructure catalyst from Example 2; Figure 4 This is a scanning electron microscope image of the TiN-Fe2O3 heterostructure catalyst from Example 3; Figure 5 This is a scanning electron microscope image of the TiN material in Comparative Example 1; Figure 6 These are the XRD patterns from Examples 1, 2, 3, and Comparative Example 1. Detailed Implementation

[0028] The embodiments of this application are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0029] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0031] A first aspect of this application provides a TiN-Fe2O3 heterostructure catalyst. The TiN-Fe2O3 heterostructure catalyst includes a core and a shell located on at least a portion of the surface of the core. The core comprises titanium nitride, and the shell comprises ferric oxide.

[0032] The presence of a heterojunction between titanium nitride and ferric oxide in the TiN-Fe2O3 heterostructure catalyst of this application embodiment can effectively improve the separation rate of photogenerated electrons and holes, thereby effectively improving the electrode reaction kinetics of the battery containing the TiN-Fe2O3 heterostructure catalyst.

[0033] Specifically, the shell structure enables the formation of a large-area, dense heterojunction interface between TiN and Fe2O3. This interface facilitates the formation of a strong built-in electric field between the core and the shell. When the Fe2O3 shell is photoexcited to generate electron-hole pairs, the built-in electric field drives photogenerated electrons to rapidly transfer from the conduction band of Fe2O3 to the TiN core, while retaining holes in the Fe2O3 shell. This achieves highly efficient spatial separation of photogenerated carriers, greatly suppressing recombination and improving charge separation efficiency. Using highly conductive TiN as the core provides a rapid conduction network for electrons injected from the Fe2O3 shell. Electrons can migrate at high speed in the TiN core, similar to their speed in metals, and are quickly transported to current collectors or reactive sites, effectively overcoming the bottleneck of poor conductivity in Fe2O3 itself and significantly accelerating the charge transfer process of the electrode reaction. When this TiN-Fe2O3 heterostructure catalyst is used as the cathode in a lithium-oxygen battery, the Fe2O3 shell is directly exposed to the electrolyte or reaction atmosphere. Its surface can serve as an active site for the catalytic reaction, which is beneficial for the oxygen reduction / evolution reaction. This results in better structural stability and durability during long-term electrochemical reactions or photoelectric cycles. During discharge, the TiN core rapidly conducts electrons to promote O2 reduction; during charging, the Fe2O3 shell accumulates holes to efficiently decompose Li2O2. Under light-assisted illumination, the injection of photogenerated carriers can further reduce the battery's charge-discharge polarization, improving energy efficiency and cycle life.

[0034] In some embodiments, the TiN mass percentage is 70%-80% based on the total mass of the TiN-Fe2O3 heterostructure catalyst. Excessive titanium nitride mass can lead to insufficient growth space for the oxide, affecting the coating efficiency; insufficient titanium nitride mass can result in poor electrode conductivity. This further improves the performance of the heterostructure catalyst.

[0035] In some embodiments, the core exhibits good conductivity, the shell is enriched with holes, and a strong built-in electric field is formed between the core and the shell interface. The core particle size ensures a high specific surface area, providing a basis for a uniformly loaded Fe2O3 active shell layer, thereby increasing the effective heterojunction interface and improving the electronic conductivity of the electrode containing the TiN-Fe2O3 heterostructure catalyst, thus achieving efficient bulk charge transport. Optionally, the core particle size is 150nm-300nm, such as 150nm, 180nm, 200nm, 230nm, 260nm, 300nm, etc.

[0036] In some embodiments, the thickness of the outer shell is 10 nm-50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc. This improves the heterojunction interface stability and catalytic active sites of the TiN-Fe2O3 heterostructure catalyst, thereby enhancing its catalytic performance.

[0037] A second aspect of this application provides a method for preparing a TiN-Fe2O3 heterostructure catalyst, referring to... Figure 1 The process includes the following steps: S100: placing a fabric with titanium dioxide seed crystals in a first tetrabutyl titanate solution for reaction treatment; S200: subjecting the product obtained from the reaction treatment to nitriding with melamine to obtain titanium nitride nanorods; S300: mixing the titanium nitride nanorods, an iron salt solution, and a morphology control agent to obtain a TiN-Fe2O3 heterostructure catalyst.

[0038] The method of this application embodiment involves reacting a fabric containing titanium dioxide seeds in a first tetrabutyl titanate solution to obtain a titanium dioxide array on the fabric; then, the result of the reaction treatment is nitrided with melamine to obtain titanium nitride nanorods; the titanium nitride nanorods, an iron salt solution, and a morphology control agent are mixed. During this mixing process, the iron salt hydrolyzes to form ferric oxide, which adheres to the surface of the titanium nitride nanorods, and the morphology control agent selectively adsorbs onto specific crystal faces of the ferric oxide crystals, inhibiting the growth rate of those crystal faces, thereby causing the crystals to preferentially grow along a certain direction (such as the c-axis). This results in a TiN-Fe2O3 heterostructure catalyst with a needle-like array. Furthermore, this method is simple and easy to implement. By controlling the reaction conditions, a TiN-Fe2O3 heterostructure catalyst is obtained. Based on the presence of the heterojunction between titanium nitride and ferric oxide, it can effectively improve the separation rate of photogenerated electrons and holes, thereby effectively improving the electrode reaction kinetics of the battery containing this TiN-Fe2O3 heterostructure catalyst.

[0039] According to an embodiment of this application, S100: The fabric with titanium dioxide seed crystals is placed in a first tetrabutyl titanate solution for reaction treatment. This step, based on the fabric, pre-positions titanium dioxide seed crystals on the fabric. The seed crystals act as nucleation sites, reducing the randomness and energy barrier of heterogeneous nucleation of titanium dioxide on the fabric surface. The titanium source generated by the hydrolysis of tetrabutyl titanate in the solution preferentially and orderly epitaxially grows on these seed crystals, rather than being randomly and unevenly deposited throughout the fabric. This ensures that the final titanium dioxide has high uniformity, consistent orientation, and reproducible morphology.

[0040] In some embodiments, forming the fabric with titanium dioxide seed crystals includes: providing a fabric and pre-oxidizing the fabric; placing the pre-oxidized product in a second tetrabutyl titanate solution to obtain the fabric with titanium dioxide seed crystals. This yields seed crystals with uniform and consistent orientation.

[0041] Furthermore, the fabric includes carbon cloth.

[0042] Furthermore, pre-oxidation can introduce abundant oxygen-containing functional groups, such as hydroxyl, carboxyl, and carbonyl groups, onto the originally inert fabric surface. These polar functional groups can undergo strong chemical interactions with the subsequent hydrolysis products of the tetrabutyl titanate solution, increasing the amount of seed crystals attached and greatly enhancing the chemical bond between the seed crystals and the fabric. Optionally, the temperature is 300℃-500℃, such as 300℃, 350℃, 400℃, 450℃, 500℃, etc. Optionally, the time is 0.5h-2h, such as 0.5h, 1h, 2h, etc.

[0043] Furthermore, the second tetrabutyl titanate solution comprises isopropanol and tetrabutyl titanate. The concentration of tetrabutyl titanate in the second tetrabutyl titanate solution is 0.7 mol / L-0.9 mol / L, for example, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, etc., thereby further promoting hydrolysis to obtain seed crystals.

[0044] In some embodiments, the first tetrabutyl titanate solution comprises hydrochloric acid, tetrabutyl titanate, and water, wherein the volume ratio of hydrochloric acid, tetrabutyl titanate, and water is 1:(0.01-0.1):(0.5-2). Under the control of a strong acid, the slow hydrolysis of the first tetrabutyl titanate solution can produce TiO2 with high crystallinity and uniform morphology on fabrics. This TiO2 determines the size and morphology of the TiN core obtained subsequently by nitriding.

[0045] Optionally, the reaction time is 8h-15h, such as 8h, 9h, 10h, 11h, 12h, 13h, 15h, etc., and the temperature is 100℃-200℃, such as 100℃, 130℃, 150℃, 180℃, 200℃, etc.

[0046] According to an embodiment of this application, S200: The product obtained from the reaction treatment is nitrided with melamine to obtain titanium nitride nanorods. In this step, the mixed atmosphere generated by the pyrolysis of melamine, such as NH3 and HCN, has strong reducing properties and can effectively reduce the titanium nitride content. 4+ Restore to Ti 3+ / Ti 2+ And N atoms gradually replace O atoms to form TiN.

[0047] In some embodiments, the nitriding treatment is carried out in an inert atmosphere by heating to 700℃-900℃ at a heating rate of 3℃ / min-6℃ / min and holding for 1h-3h. This nitriding treatment allows titanium dioxide to be converted in situ into titanium nitride nanorods.

[0048] Further, the mass ratio of melamine to titanium nitride nanorods is (10-20):1. Optionally, the amount of melamine used is 1g-2g.

[0049] According to an embodiment of this application, S300: The titanium nitride nanorods, iron salt solution, and morphology control agent are mixed to obtain a TiN-Fe2O3 heterostructure catalyst. In this step, the iron salt provides the iron source, and the morphology control agent promotes Fe2O3 growth by controlling the specific growth direction of the crystals. 3+ Ions are progressively hydrolyzed and deposited onto the surface of TiN nanorods. The hydrolysis kinetics of the morphology control agent are controllable in the aforementioned process, which can regulate the formation rate of Fe(OH)3 precursor in solution, thereby controlling the deposition thickness, grain size and crystallization of Fe2O3.

[0050] In some embodiments, the mass ratio of the titanium nitride nanorods, the iron salt, and the morphology control agent is 1:(1-2):(3-8). Thus, the morphology control agent selectively adsorbs onto specific crystal faces of the iron oxide crystal, inhibiting the growth rate of those faces, thereby causing the crystal to preferentially grow along a certain direction (such as the C-axis), resulting in a TiN-Fe2O3 heterostructure catalyst with a needle-like array.

[0051] Optionally, the iron salt is selected from at least one of ferric chloride, ferric sulfate, and ferric nitrate.

[0052] Optionally, the morphology control agent includes at least one of sodium sulfate.

[0053] In some embodiments, the mixing temperature is 100℃-150℃, such as 100℃, 110℃, 120℃, 130℃, 150℃, etc., and the mixing time is 1h-6h, such as 1h, 2h, 3h, 4h, 5h, 6h, etc. Thus, a TiN-Fe2O3 heterostructure catalyst with a needle-like array is further obtained.

[0054] A third aspect of this application provides a lithium-oxygen battery. The battery includes a positive electrode, which comprises a current collector and a positive electrode active material layer located on at least one side of the current collector. The positive electrode active material layer comprises the TiN-Fe2O3 heterostructure catalyst described in the first aspect or a TiN-Fe2O3 heterostructure catalyst prepared using the preparation method described in the second aspect. In this battery, the positive electrode active material layer includes a TiN-Fe2O3 heterostructure catalyst, and the TiN-Fe2O3 heterostructure establishes a strong built-in electric field. This electric field acts as a highly efficient charge pump, forcibly separating and directionally transporting photogenerated electrons and holes to electron-to-conductive channels and holes-to-reaction sites, thereby significantly improving charge separation and transport efficiency, enhancing the ORR and OER reaction kinetics on the positive electrode surface, and thus improving the performance of the lithium-oxygen battery, specifically by effectively reducing the battery's charge / discharge overpotential.

[0055] In some embodiments, the lithium-oxygen battery further includes a negative electrode and an electrolyte, wherein the negative electrode is a lithium metal sheet, the electrolyte includes an electrolyte and a solvent, the electrolyte includes lithium trifluoromethanesulfonate, and the solvent includes tetraethylene glycol dimethyl ether, wherein the concentration of the electrolyte in the electrolyte is 0.5 mol / L-2 mol / L.

[0056] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0057] Example 1 S1. Arrange the carbon in a muffle furnace and pre-oxidize it at 400℃ for 1 hour.

[0058] S2. The carbon obtained in S1 is immersed in a 0.08M tetrabutyl isopropoxide titanate seed solution to prepare TiO2 seed crystals.

[0059] S3. Prepare a growth solution consisting of 1.32 ml tetrabutyl titanate, 40 ml hydrochloric acid, and 40 ml deionized water.

[0060] S4. The carbon array obtained in S2 is placed into the solution obtained in S3 and then placed in a high-temperature reactor with a polytetrafluoroethylene liner and kept at 150°C for 10 hours.

[0061] S5. Place the carbon cloth obtained in S4 and 1g of melamine in a tube furnace and anneal at 800℃ with Ar gas as a protective gas to obtain titanium nitride nanorods.

[0062] S6. Prepare a mixed solution by mixing 35 mL of ferric chloride hexahydrate (0.015 M) and 35 mL of sodium sulfate (0.01 M). S7. The carbon obtained in S5 was arranged in the mixed solution prepared in S6, and then placed in a high-temperature reactor with a polytetrafluoroethylene liner. The reaction was carried out at 130℃ for 1 h to obtain a TiN-Fe2O3 heterostructure catalyst. Scanning electron microscopy (SEM) analysis of the TiN-Fe2O3 heterostructure catalyst was performed; the results are shown below. Figure 2 As can be seen from the figure, iron oxide is coated on titanium nitride in a film-like manner.

[0063] Example 2 The TiN-Fe2O3 heterostructure catalyst was prepared according to Example 1, except that in S7, the reaction was carried out at 130°C for 3 h to obtain the TiN-Fe2O3 heterostructure catalyst. Scanning electron microscopy was performed on the TiN-Fe2O3 heterostructure catalyst, and the results are shown below. Figure 3 As can be seen from the figure, needle-shaped iron oxide coated titanium nitride arrays were successfully prepared with uniform thickness.

[0064] Example 3 The TiN-Fe2O3 heterostructure catalyst was prepared according to Example 1, except that in S7, the reaction was carried out at 130°C for 6 h to obtain the TiN-Fe2O3 heterostructure catalyst. Scanning electron microscopy was performed on the TiN-Fe2O3 heterostructure catalyst, and the results are shown below. Figure 4 As can be seen from the figure, the thickness of the oxide shell increases over time.

[0065] Comparative Example 1 S1. Arrange the carbon in a muffle furnace and pre-oxidize it at 400℃ for 1 hour.

[0066] S2. The carbon obtained in S1 is immersed in a 0.08M tetrabutyl isopropoxide titanate seed solution to prepare TiO2 seed crystals.

[0067] S3. Prepare a growth solution consisting of 1.32 ml tetrabutyl titanate, 40 ml hydrochloric acid, and 40 ml deionized water.

[0068] S4. The carbon array obtained in S2 is placed into the solution obtained in S3 and then placed in a high-temperature reactor with a polytetrafluoroethylene liner and kept at 150°C for 10 hours.

[0069] S5. The carbon cloth obtained in S4 and 1g of melamine were placed in a tube furnace and annealed at 800℃ using Ar gas as a protective gas to obtain titanium nitride nanorod catalyst. Scanning electron microscopy was performed on the titanium nitride nanorod catalyst, and the results are shown below. Figure 5 The figure shows the titanium nitride nanoarray structure.

[0070] Figure 6These are the XRD patterns of Examples 1, 2, 3 and Comparative Example 1. In this example, TiN@Fe2O31h corresponds to the catalyst of Example 1, TiN@Fe2O33h corresponds to the catalyst of Example 2, TiN@Fe2O36h corresponds to the catalyst of Example 3, and TiN corresponds to the catalyst of Comparative Example 1. As can be seen from the figure, the prepared material has no other impurities, and the content of oxides increases with time.

[0071] Application examples The catalyst obtained above was used to prepare a lithium-air battery. The battery preparation process is as follows: Carbon cloth with a TiN-Fe2O3 heterostructure material was directly used as the positive electrode of the lithium-oxygen battery. A lithium metal sheet was used as the negative electrode. The electrolyte consisted of an electrolyte and a solvent; the electrolyte included lithium trifluoromethanesulfonate, and the solvent included tetraethylene glycol dimethyl ether. The concentration of the electrolyte in the electrolyte was 1 mol / L. A 670 μm thick glass fiber filter membrane was used as the separator. The lithium-oxygen battery was prepared by assembling the battery in the following order: negative electrode shell, negative electrode, separator, positive electrode, and positive electrode shell. An appropriate amount of electrolyte was then added to complete the assembly.

[0072] The battery samples containing the catalysts of Examples 1-3 are designated D1, D2, and D3 respectively, and the battery containing the catalyst of Comparative Example 1 is designated D4. Overpotential performance tests were performed on D1, D2, D3, and D4, and the results are shown in Table 1 below. The overpotential performance test was conducted using a 300W xenon lamp under illumination to test the overpotential of the battery during its first charge-discharge cycle.

[0073] Table 1

[0074] As can be seen from the table above, the overpotentials of the batteries in Examples 1-3 are superior to those of the battery in Comparative Example 1. This is because the presence of the heterojunction between titanium nitride and ferric oxide in the TiN-Fe2O3 heterostructure catalyst of this application can effectively improve the separation rate of photogenerated electrons and holes, thereby effectively improving the electrode reaction kinetics of the battery containing this TiN-Fe2O3 heterostructure catalyst.

[0075] It should also be noted that the terms "some embodiments," "other embodiments," and "embodiments" used in this application refer to specific features, structures, or characteristics described in connection with those embodiments, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0077] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of protection of this application. Any equivalent structural or procedural transformations made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of protection of this application.

Claims

1. A TiN-Fe2O3 heterostructure catalyst, characterized in that, It includes a core and a shell located on at least a portion of the surface of the core, the contact interface between the core and the shell being a heterojunction interface, the core comprising titanium nitride and the shell comprising ferric oxide.

2. The TiN-Fe2O3 heterostructure catalyst according to claim 1, characterized in that, Based on the total mass of the TiN-Fe2O3 heterostructure catalyst, the mass percentage of TiN is 70%-80%.

3. The TiN-Fe2O3 heterostructure catalyst according to claim 1 or 2, characterized in that, The particle size of the core is 150nm-300nm; The thickness of the shell is 20nm-70nm.

4. A method for preparing a TiN-Fe2O3 heterostructure catalyst, characterized in that, Includes the following steps: The fabric containing titanium dioxide seed crystals was placed in a first tetrabutyl titanate solution for reaction treatment. The product obtained from the reaction treatment was subjected to nitriding with melamine to obtain titanium nitride nanorods; The titanium nitride nanorods, iron salt solution, and morphology control agent were mixed to obtain a TiN-Fe2O3 heterostructure catalyst.

5. The preparation method according to claim 4, characterized in that, The method of forming the fabric with titanium dioxide seed crystals includes: Provide a fabric and pre-oxidize the fabric; The pre-oxidized product is placed in a second tetrabutyl titanate solution to obtain the fabric with titanium dioxide seed crystals.

6. The preparation method according to claim 5, characterized in that, The fabric includes carbon cloth; And / or, the pre-oxidation temperature is 300℃-500℃, and the time is 0.5h-2h; And / or, the second tetrabutyl titanate solution comprises isopropanol and tetrabutyl titanate; And / or, the concentration of tetrabutyl titanate in the second tetrabutyl titanate solution is 0.7 mol / L-0.9 mol / L.

7. The preparation method according to claim 4 or 5, characterized in that, The first tetrabutyl titanate solution comprises hydrochloric acid, tetrabutyl titanate and water, wherein the volume ratio of hydrochloric acid, tetrabutyl titanate and water is 1:(0.01-0.1):(0.5-2); The reaction time is 8h-15h, and the temperature is 100℃-200℃; The nitriding treatment is carried out in an inert atmosphere, with the temperature increased to 700℃-900℃ at a rate of 3℃ / min-6℃ / min and held for 1h-3h.

8. The method according to claim 4 or 5, characterized in that, The mixture satisfies at least one of the following conditions: The mass ratio of the titanium nitride nanorods, the iron salt, and the morphology control agent is 1:(1-2):(3-8); The iron salt includes at least one of ferric chloride, ferric sulfate, and ferric nitrate; The morphology control agent includes at least one of sodium sulfate; The temperature is 100℃-150℃, and the time is 1h-6h.

9. A lithium-oxygen battery, characterized in that, The catalyst includes a positive electrode sheet, wherein the positive electrode sheet includes a positive electrode active material layer, and the positive electrode active material layer includes the TiN-Fe2O3 heterostructure catalyst according to any one of claims 1-3 or the TiN-Fe2O3 heterostructure catalyst prepared by the preparation method according to any one of claims 4-8.

10. The lithium-oxygen battery according to claim 9, characterized in that, It also includes a negative electrode sheet and an electrolyte, wherein the negative electrode sheet is a lithium metal sheet, and the electrolyte includes an electrolyte and a solvent, wherein the electrolyte includes lithium trifluoromethanesulfonate, and the solvent includes tetraethylene glycol dimethyl ether, wherein the concentration of the electrolyte in the electrolyte is 0.5 mol / L-2 mol / L.

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