Binary metal monatomic catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and particularly discloses a binary metal monatomic catalyst as well as a preparation method and application thereof. The binary metal monatomic catalyst comprises a P and N co-doped carbon substrate, Ni atoms and Sn atoms, the Ni atoms and the Sn atoms are loaded on the surface of the carbon substrate in a coordinate bond mode, the binary metal monatomic catalyst is of a sheet structure, and the surface of the binary metal monatomic catalyst is in a wrinkle shape. According to the N-P co-doped binary metal monatomic catalyst with Sn-Ni as the bimetallic center, by cooperatively regulating and controlling the electronic structure of bimetallic atoms, efficient catalysis of carbon dioxide electroreduction and water electrolysis oxygen evolution catalytic activity is achieved, and long circulation of a chargeable and dischargeable water system Zn-CO2 battery is achieved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a binary metal single-atom catalyst, its preparation method, and its application. Background Technology

[0002] Zn-CO2 batteries are a novel type of energy storage device. During discharge, they not only supply power but also perform electrocatalytic carbon dioxide reduction reaction (CO2RR), converting carbon dioxide into industrially valuable products such as carbon monoxide, methane, and ethylene. During charging, oxygen is released through water electrolysis, thus storing electrical energy as chemical energy. To achieve these functions, the cathode catalyst of the Zn-CO2 battery must possess catalytic activity for both carbon dioxide reduction and oxygen evolution through water electrolysis. However, carbon dioxide molecules are highly stable and difficult to activate, while water oxidation requires a high potential, placing high demands on the structural stability of the catalyst. Achieving high CO2 reduction and water oxidation rates, along with a large current, has been a continuous research focus for scientists.

[0003] Metal single-atom catalysts are catalysts in which metal atoms are dispersed as individual atoms on a substrate, allowing all metals to be exposed on the catalyst surface and act as active sites, thus improving the utilization rate of metal atoms. Each individual metal atom interacts with the support to form an independent catalytic active center with consistent catalytic behavior, thereby improving catalytic selectivity. The catalytic activity of metal single atoms can be achieved by doping the substrate with heteroatoms and other metal atoms, which can couple the electronic structures between them, thereby enabling functional catalysis.

[0004] The structure and catalytic activity of metal single-atom catalysts can be modulated through the type of the metal center element M-X4 (M being different metals, such as Fe, Co, Ni, Sn, Cu, etc.; X being non-metallic coordinating atoms such as N, O, etc.) and coordinating heteroatoms. Numerous studies have used these two methods to regulate the activity and selectivity of metal single-atom catalysts in the electroreduction of carbon dioxide to produce CO, formic acid, methane, ethylene, and ethanol. However, these catalysts often exhibit only single electrocatalytic activity for carbon dioxide, lacking or possessing only very weak oxygen evolution reaction (OER) activity, failing to meet the requirements of cathode catalysts for rechargeable Zn-CO2 batteries. Therefore, there is an urgent need to develop a novel bifunctional single-atom catalyst that can regulate the structure and catalytic activity of metal single atoms, possessing high metal loading, strong selectivity, good stability, and the ability to electroreductize carbon dioxide and electrolyze water for OER. Summary of the Invention

[0005] In view of this, the present invention provides a binary metal single-atom catalyst, its preparation method and application.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: The present invention provides a binary metal single-atom catalyst comprising a carbon substrate co-doped with P and N, and Ni atoms and Sn atoms supported on the surface of the carbon substrate in the form of coordination bonds. The binary metal single-atom catalyst has a sheet-like structure with a wrinkled surface.

[0007] Compared with the prior art, the binary metal single-atom catalyst provided by the present invention has a sheet-like structure with a wrinkled surface, which greatly increases the specific surface area of ​​the catalyst and improves its catalytic performance.

[0008] In this invention, Ni atoms and Sn atoms synergistically regulate the electronic structure of the metal center, which is beneficial to simultaneously improving the catalyst's activity for carbon dioxide catalysis and oxygen evolution through water electrolysis. Meanwhile, because P atoms have a larger atomic radius and stronger electron-donating ability, they can form π bonds with Ni and Sn atoms that couple with pd orbitals, resulting in stronger electron delocalization characteristics and a larger space for regulating the valence state of the metal center. This significantly improves the catalyst's catalytic activity for oxygen evolution through water electrolysis and for the electroreduction of carbon dioxide to carbon monoxide.

[0009] The present invention provides a binary metal single-atom catalyst with Sn-Ni as the bimetallic center and NP co-doped. By synergistically regulating the electronic structure of the bimetallic atoms, it achieves highly efficient catalytic activity for carbon dioxide electroreduction and water electrolysis oxygen evolution, and realizes long-cycle rechargeable water-based Zn-CO2 batteries.

[0010] This invention provides a method for preparing the above-mentioned binary metal single-atom catalyst, comprising the following steps: S1. Mix 2-aminoterephthalic acid and N,N-dimethylformamide (DMF) evenly, and then add an aluminum source at 70~150℃ to react and obtain Mil-101-NH2; S2. Disperse the Mil-101-NH2 in a hydrophobic solvent to obtain a Mil-101-NH2 dispersion; S3. Add nickel source, tin source, phosphorus source and nitrogen source to N,N-dimethylformamide, then add the Mil-101-NH2 dispersion to react, separate the solid and liquid, and dry to obtain (Ni-Sn)@Mil-101-NH2; S4. Under an inert atmosphere, the (Ni-Sn)@Mil-101-NH2 is subjected to two pyrolysis carbonization treatments to obtain a binary metal single-atom catalyst.

[0011] Compared to existing technologies, the preparation method of the binary metal single-atom catalyst provided by this invention achieves uniform loading and efficient interaction between nickel and tin binary metal components and phosphorus and nitrogen sources through dispersion treatment by mixing Mil-101-NH2 and hydrophobic solvent. Combined with a two-stage pyrolysis carbonization process under an inert atmosphere, it ensures the monodispersity and high utilization rate of metal atoms, and enhances the catalytic activity, selectivity and structural stability of the catalyst through the synergistic effect of binary metals. Moreover, the process parameters are controllable, the operation is simple and highly reproducible, providing a reliable path for the large-scale preparation of high-performance binary metal single-atom catalysts.

[0012] Preferably, in S1, the aluminum source is aluminum chloride.

[0013] Preferably, in S1, the mass ratio of 2-aminoterephthalic acid to aluminum source is 1:(1~3).

[0014] Preferably, in S1, the mass-to-volume ratio of 2-aminoterephthalic acid and N,N-dimethylformamide is 1 g: (100~300) mL.

[0015] Preferably, in S1, the reaction time is 2 to 8 hours.

[0016] For example, in S1, the reaction is carried out under static conditions.

[0017] It should be further noted that before the reaction, the mixture needs to be stirred at a speed of 300-600 rpm for 2-6 hours.

[0018] Preferably, in S1, after the reaction is completed, the reaction product is centrifuged, washed, extracted with ethanol, and dried to obtain Mil-101-NH2.

[0019] More preferably, the washing solvent is DMF and ethanol.

[0020] More preferably, the drying conditions are drying at 100°C in a vacuum drying oven.

[0021] Preferably, in S2, the hydrophobic solvent is n-hexane.

[0022] It should be further clarified that the n-hexane is ultra-dry n-hexane.

[0023] Preferably, in S2, the mass-to-volume ratio of Mil-101-NH2 to the hydrophobic solvent is (4~6) mg:1 mL.

[0024] For example, in S2, the Mil-101-NH2 is dispersed in a hydrophobic solvent, stirred for 5 minutes, and then ultrasonically dispersed for 30 minutes. The parameters of stirring and ultrasonication are not further limited, and conventional operating methods known to those skilled in the art can be used.

[0025] Preferably, in S3, the nickel source includes at least one of nickel chloride or nickel nitrate.

[0026] Preferably, in S3, the tin source includes at least one of tin chloride or tin nitrate.

[0027] Preferably, in S3, the phosphorus source includes triphenylphosphine.

[0028] During their research, the inventors discovered that when triphenylphosphine is chosen as the phosphorus source, it has three PC bonds and P also has a pair of lone pairs of electrons, which can coordinate with metals to form a coordination structure. In the subsequent pyrolysis and carbonization process, it coordinates with metal atoms through coordination bonds, thereby significantly improving the catalytic activity of the catalyst.

[0029] Preferably, in S3, the nitrogen source includes at least one of urea, dicyandiamide, or polyaniline.

[0030] Preferably, in S3, the mass-to-volume ratio of the nickel source, tin source, phosphorus source, nitrogen source and N,N-dimethylformamide is (50~150) mg:(50~150) mg:(50~150) mg:(50~150) mg:(1~10) mL.

[0031] This invention further optimizes the ratio of nickel source, tin source, phosphorus source, nitrogen source and N,N-dimethylformamide, which is beneficial to further improve the catalytic performance of the catalyst and enable it to simultaneously have highly efficient catalytic activity for carbon dioxide electroreduction and water electrolysis oxygen evolution.

[0032] Preferably, in S3, the mass ratio of the nickel source to Mil-101-NH2 is (50~150):500.

[0033] It should be further noted that in S3, the Mil-101-NH2 dispersion needs to be added slowly dropwise under high-speed stirring conditions. Here, the high-speed stirring conditions are not further limited, and conventional methods mastered by those skilled in the art can be used.

[0034] For example, the conditions for slow dripping are: controlling the dripping time to be 30~35 minutes.

[0035] Preferably, in step S4, the inert atmosphere is an argon atmosphere.

[0036] Preferably, in S4, the conditions for the first pyrolysis carbonization treatment in the two pyrolysis carbonization treatments are: 1~5℃·min -1 The temperature is increased to 550~650℃ at a certain rate for the first heat preservation.

[0037] More preferably, the first heat preservation time is 1 to 3 hours.

[0038] Preferably, in S4, the conditions for the first pyrolysis carbonization treatment in the two pyrolysis carbonization treatments are: 1~5℃·min -1 The temperature is increased to 800~900℃ at a certain rate for a second heat preservation.

[0039] More preferably, the second heat preservation time is 2-4 hours.

[0040] The present invention further specifies the specific conditions for the two pyrolysis carbonization processes. During the first pyrolysis carbonization process, a portion of the nitrogen source is carbonized to form phosphorus and nitrogen co-doped carbon, which facilitates the fixation of metal atoms and ensures that the metal atoms exist in the form of single atoms. The second pyrolysis carbonization process pyrolyzes the material into phosphorus and nitrogen co-doped graphite carbon, thereby improving the electronic conductivity of the material.

[0041] It should be further explained that in S4, after the pyrolysis carbonization treatment is completed, the product is cooled to room temperature, then immersed in a 20wt% HF solution, centrifuged, washed, and dried to obtain the binary metal single-atom catalyst.

[0042] This invention provides the application of the above-mentioned binary metal single-atom catalyst in the preparation of zinc-air batteries or in the oxygen evolution reaction and carbon dioxide reduction reaction of water electrolysis.

[0043] Compared with the prior art, the present invention has the following beneficial effects: (1) Compared with existing single-atom catalysts, the Ni and Sn binary metal single-atom catalyst provided by this invention has a plate-like structure with metal atoms uniformly distributed on the catalyst surface and the surface is wrinkled. This greatly increases the contact area between the catalyst and the electrolyte, providing active sites for carbon dioxide reduction reaction and water electrolysis oxygen evolution reaction. In addition, the uniform distribution of metal atoms on the catalyst surface in the binary metal single-atom catalyst provided by this invention further improves the utilization rate of atoms. The metal atoms are tightly bonded to the support and have a complete structure, which further improves the catalytic activity and service life of the catalyst. (2) The Zn-CO2 battery assembled using the binary metal single-atom catalyst provided by this invention can achieve a maximum power of 25 mW·cm⁻¹. -2 The open-circuit voltage can reach 1.18V, at 5mW·cm -2 The current can cycle more than 70 times without significant attenuation. Attached Figure Description

[0044] Figure 1 Transmission electron microscopy (TEM) image of nickel and tin binary metal single atoms in the binary metal single-atom catalyst prepared in Example 1 of this invention; Figure 2 The X-ray diffraction pattern of nickel and tin binary metal single atoms in the binary metal single-atom catalyst provided in Example 1 of the present invention; Figure 3 X-ray photoelectron spectroscopy of nickel in the binary metal single-atom catalyst provided in Example 1 of this invention; Figure 4 X-ray photoelectron spectroscopy of tin in the binary metal single-atom catalyst provided in Example 1 of this invention. Figure 5 The graph shows the performance of a zinc-air battery using a carbon paper electrode loaded with the binary metal single-atom catalyst provided in Example 1 of this invention as the cathode. Figure 6 The graph shows the performance of a zinc-air battery using a carbon paper electrode loaded with the binary metal single-atom catalyst provided in Comparative Example 1 of this invention as the cathode. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] Example 1 This embodiment provides a method for preparing a binary metal single-atom catalyst, comprising the following steps: S1. Add 2-aminoterephthalic acid (2.72 g) and DMF (600 mL) to a flask and stir vigorously. Heat the resulting suspension to 110 °C and add aluminum chloride hexahydrate (7.24 g) after 15 min. Stir at 600 rpm for 3 h and then let it stand for 2 h. After the solution cools to room temperature, centrifuge and wash with DMF and ethanol alternately. Then extract the resulting yellow powder with ethanol by Soxhlet extraction for 24 h and dry it in a vacuum oven at 100 °C to obtain Mil-101-NH2. S2. Disperse Mil-101-NH2 (500 mg) in ultra-dry n-hexane (100 mL), stir for 5 min, and then sonicate for 30 min until the dispersion is uniform to obtain Mil-101-NH2 dispersion; S3. Add urea (100 mg), triphenylphosphine (100 mg), nickel chloride (100 mg), and tin chloride (100 mg) to DMF (1 mL). While stirring at high speed, slowly add Mil-101-NH2 dispersion dropwise over a period of about 30 min. Stir the resulting solution continuously until the solid precipitates to the bottom, forming a colloidal solid. Slowly pour out the liquid for solid-liquid separation. Further dry the obtained solid under vacuum at 100 °C for 24 h to obtain (Ni-Sn)@Mil-101-NH2. S4. Transfer (Ni-Sn)@Mil-101-NH2 into a ceramic boat and perform a two-stage pyrolysis carbonization process in an argon gas furnace (first stage: at 3℃·min). -1 The temperature was increased to 600℃ at a heating rate and held for 1 hour; the second stage was carried out at a heating rate of 3℃·min. -1 The temperature was raised to 900℃ and held for 2 hours, then cooled to room temperature. The resulting solid was then immersed in HF (20wt%) solution for 48 hours to remove residual metal nanoparticles and unstable components. The solid was further centrifuged and vacuum dried at 100℃ for 24 hours to obtain a binary metal single-atom catalyst, denoted as SA-Ni-Sn@NP / C.

[0047] Example 2 This embodiment provides a method for preparing a binary metal single-atom catalyst, comprising the following steps: S1. Add 2-aminoterephthalic acid (2.72 g) and DMF (600 mL) to a flask and stir vigorously. Heat the resulting suspension to 70 °C. After 15 min, add aluminum chloride hexahydrate (8 g) and stir at 600 rpm for 4 h. Then let the reaction stand for 2 h. After the solution cools to room temperature, centrifuge and wash alternately with DMF and ethanol. Then extract the resulting yellow powder with ethanol using Soxhlet extraction for 24 h and dry it in a vacuum oven at 100 °C to obtain Mil-101-NH2. S2. Disperse Mil-101-NH2 (500 mg) in ultra-dry n-hexane (100 mL), stir for 5 min, and then sonicate for 30 min until the dispersion is uniform to obtain Mil-101-NH2 dispersion; S3. Add urea (150 mg), triphenylphosphine (150 mg), nickel chloride (150 mg), and tin chloride (150 mg) to DMF (5 mL). While stirring at high speed, slowly add Mil-101-NH2 dispersion over a period of about 30 min. Stir the solution continuously until the solid precipitates to the bottom and forms a colloidal solid. Slowly pour out the liquid for solid-liquid separation. Dry the solid at 100 °C under vacuum for 24 h to obtain (Ni-Sn)@Mil-101-NH2. S4. Transfer (Ni-Sn)@Mil-101-NH2 into a ceramic vessel and perform a two-stage pyrolysis carbonization process in an argon gas furnace (first stage: at 5℃·min). -1 The temperature was increased to 550℃ at a heating rate and held for 2 hours; the second stage was carried out at a heating rate of 5℃·min. -1 The temperature was increased to 850℃ and held for 3 hours, then cooled to room temperature. The resulting solid was then immersed in HF (20wt%) solution for 48 hours to remove residual metal nanoparticles and unstable components. The solid was further centrifuged and vacuum dried at 100℃ for 24 hours to obtain a binary metal single-atom catalyst.

[0048] Example 3 This embodiment provides a method for preparing a binary metal single-atom catalyst, comprising the following steps: S1. Add 2-aminoterephthalic acid (2.72 g) and DMF (600 mL) to a flask and stir vigorously. Heat the resulting suspension to 150 °C and add aluminum chloride hexahydrate (3 g) after 15 min. Keep stirring at 600 rpm for 5 h and then let the reaction stand for 2 h. After the solution cools to room temperature, centrifuge and wash alternately with DMF and ethanol. Then extract the resulting yellow powder with ethanol by Soxhlet extraction for 24 h and dry it in a vacuum oven at 100 °C to obtain Mil-101-NH2. S2. Disperse Mil-101-NH2 (500 mg) in ultra-dry n-hexane (100 mL), stir for 5 min, and then sonicate for 30 min until the dispersion is uniform to obtain Mil-101-NH2 dispersion; S3. Add urea (130 mg), triphenylphosphine (130 mg), nickel chloride (130 mg), and tin chloride (130 mg) to DMF (10 mL). While stirring at high speed, slowly add Mil-101-NH2 dispersion over a period of about 30 min. Stir the solution continuously until the solid precipitates to the bottom, forming a colloidal solid. Slowly pour out the liquid for solid-liquid separation. Dry the obtained solid under vacuum at 100 °C for 24 h to obtain (Ni-Sn)@Mil-101-NH2. S4. Transfer (Ni-Sn)@Mil-101-NH2 into a ceramic vessel and perform a two-stage pyrolysis carbonization process in an argon gas furnace (first stage: at 4℃·min). -1 The temperature was increased to 650℃ at a heating rate and held for 3 hours; the second stage was carried out at a heating rate of 4℃·min. -1The temperature was increased to 800℃ and held for 4 hours, then cooled to room temperature. The resulting solid was then immersed in HF (20wt%) solution for 48 hours to remove residual metal nanoparticles and unstable components. The solid was further centrifuged and vacuum dried at 100℃ for 24 hours to obtain a binary metal single-atom catalyst.

[0049] Comparative Example 1 This comparative example provides a method for preparing a catalyst, which differs from Example 1 in that triphenylphosphine is not added; Specifically, the steps include the following: S1. Add 2-aminoterephthalic acid (2.72 g) and DMF (600 mL) to a flask and stir vigorously. Heat the resulting suspension to 110 °C and add aluminum chloride hexahydrate (7.24 g) after 15 min. Keep stirring at 600 rpm for 3 h, then let the reaction stand for 2 h. After the solution cools to room temperature, centrifuge and wash alternately with DMF and ethanol. Then extract the resulting yellow powder with ethanol by Soxhlet extraction for 24 h and dry it in a vacuum oven at 100 °C to obtain Mil-101-NH2. S2. Disperse Mil-101-NH2 (500 mg) in ultra-dry n-hexane (100 mL), stir for 5 min, and then sonicate for 30 min until the dispersion is uniform to obtain Mil-101-NH2 dispersion; S3. Add urea (100 mg), nickel chloride (100 mg), and tin chloride (100 mg) to DMF (1 mL). While stirring at high speed, slowly add Mil-101-NH2 dispersion dropwise over a period of about 30 min. Stir the resulting solution continuously until the solid precipitates to the bottom, forming a colloidal solid. Slowly pour out the liquid for solid-liquid separation. Further dry the obtained solid under vacuum at 100 °C for 24 h to obtain (Ni-Sn)@Mil-101-NH2. S4. Transfer (Ni-Sn)@Mil-101-NH2 into a ceramic boat and perform a two-stage pyrolysis carbonization process in an argon gas furnace (first stage: at 3℃·min). -1 The temperature was increased to 600℃ at a heating rate and held for 1 hour; the second stage was carried out at a heating rate of 3℃·min. -1 The temperature was raised to 900℃ and held for 2 hours, then cooled to room temperature. The resulting solid was then immersed in HF (20wt%) solution for 48 hours to remove residual metal nanoparticles and unstable components. The solid was further centrifuged and vacuum dried at 100℃ for 24 hours to obtain a Ni-Sn binary metal single-atom catalyst SA-Ni-Sn@N / C with only nitrogen doping.

[0050] Example of effect Preparation and testing conditions: Electrode preparation process: 10 mg of the catalysts provided in Example 1 and Comparative Example 1 were dispersed in 2 mL of a 1:1 volume ratio mixture of ethanol and isopropanol in 5 wt% perfluorosulfonic acid resin solution (Nafion solution), and ultrasonically treated for 2 h. The mixture was then drop-coated onto carbon paper with a gas diffusion layer (geometric area of ​​2 cm × 0.5 cm), with a catalyst loading of approximately 1 mg·cm⁻¹. -2 And air dry them for experimental use.

[0051] Water-based rechargeable Zn CO2 battery structure: The cathode and anode chambers are separated by an anion exchange membrane (AEM). The anode chamber is filled with KOH (6M) and Zn(CH3COO)2 (0.2M), while the cathode chamber is filled with 1M KOH. A gas diffusion chamber is also provided on the cathode side. During the measurement, the gas diffusion chamber on the cathode side is filled with KOH at a rate of 24 mL / min. -1 CO2 is injected at a rate of [missing information]; the anode electrode is a Zn plate, and the cathode electrode is the catalyst prepared above containing [missing information] (1.0 mg·cm⁻¹). -2 The battery used a carbon paper electrode; measurements were performed using a CHI 660E electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) and a CT2001A (LANHE) testing system, with the current controlled at 5 mA·cm during charge-discharge cycle testing. -2 The battery is charged for 10 minutes and then discharged for 10 minutes, alternating between the two. The initial charging cutoff voltage is 2.75V, and the discharging cutoff voltage is 1.25V. As the charge-discharge cycle progresses and the battery performance deteriorates, the charging cutoff voltage will be significantly higher than the initial voltage of 2.75V or significantly lower than 1.25V.

[0052] Depend on Figure 1 It can be seen that in the catalyst SA-Ni-Sn@NP / C provided in Example 1 of the present invention, bright spots are uniformly distributed on the surface, which means that nickel and tin metal single atoms are dispersed on the carbon substrate; Figure 2 The X-ray diffraction pattern of the bimetallic single-atom catalyst provided in Example 1 shows that no diffraction peaks of metal nanoparticles were found, further indicating the presence of individual metal single atoms in the catalyst. Figure 3 and Figure 4 X-ray photoelectron spectroscopy (XPS) of Ni and Sn elements in the catalyst SA-Ni-Sn@NP / C provided in Example 1 showed that they both existed in the oxidation state, with no metallic state detected, further proving that they existed in the form of single atoms. A Zn-CO2 battery was assembled using a carbon paper electrode supported on the tin and nickel binary single-atom catalyst provided in Example 1 as the positive electrode and a zinc sheet as the negative electrode. Figure 5 (a) is a charge-discharge curve of a zinc-air battery. Figure 5 (b) is a power curve of a zinc-air battery. Figure 5 (a) and Figure 5 (b) Test results show that at 50 mA·cm -2 At a current density of 25 mW·cm, it exhibits 25 mW·cm -2 The power density. Furthermore, at 5 mA·cm⁻¹ -2 Charge-discharge tests were conducted at current densities. Figure 5 (c) is a charge-discharge cycle curve of a zinc-air battery. Figure 5 (c) The test results show that the Zn-CO2 battery does not show significant performance degradation within 70 hours; while the catalyst provided in Comparative Example 1 is a Ni-Sn binary metal single-atom catalyst doped only with N, SA-Ni-Sn@N / C, which is loaded onto a carbon paper electrode as the positive electrode of the Zn-CO2 battery. Figure 6 (a) is a charge-discharge curve of a zinc-air battery. Figure 6 (b) is a power curve of a zinc-air battery. Figure 6 (a) and Figure 6 (b) Test results show that the maximum power density can only reach 9.625 mW·cm. -2 This further demonstrates the superiority of P atom coordination pairs in enhancing the application of tin-nickel binary metal single-atom catalysts.

[0053] The catalysts prepared in Examples 2-3 and Example 1 all achieved comparable results.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A binary metal single-atom catalyst, characterized in that, The binary metal single-atom catalyst comprises a carbon substrate co-doped with P and N, and Ni and Sn atoms supported on the surface of the carbon substrate in the form of coordination bonds. The catalyst has a sheet-like structure with a wrinkled surface.

2. A method for preparing the binary metal single-atom catalyst according to claim 1, characterized in that, Includes the following steps: S1. Mix 2-aminoterephthalic acid and N,N-dimethylformamide (DMF) evenly, and then add an aluminum source at 70~150℃ to react and obtain Mil-101-NH2; S2. Disperse the Mil-101-NH2 in a hydrophobic solvent to obtain a Mil-101-NH2 dispersion; S3. Add nickel source, tin source, phosphorus source and nitrogen source to N,N-dimethylformamide, then add the Mil-101-NH2 dispersion to react, separate the solid and liquid, and dry to obtain (Ni-Sn)@Mil-101-NH2; S4. Under an inert atmosphere, the (Ni-Sn)@Mil-101-NH2 is subjected to two pyrolysis carbonization treatments to obtain a binary metal single-atom catalyst.

3. The method for preparing a binary metal single-atom catalyst as described in claim 2, characterized in that, In S1, the mass ratio of 2-aminoterephthalic acid to aluminum source is 1:(1~3). In S1, the mass-to-volume ratio of 2-aminoterephthalic acid and N,N-dimethylformamide is 1 g: (100~300) mL; In S1, the reaction time is 2 to 8 hours.

4. The method for preparing the binary metal single-atom catalyst as described in claim 2, characterized in that, In S2, the hydrophobic solvent is n-hexane; In S2, the mass-to-volume ratio of Mil-101-NH2 to the hydrophobic solvent is (5~5.5) mg:1 mL.

5. The method for preparing the binary metal single-atom catalyst as described in claim 2, characterized in that, In S3, the phosphorus source includes triphenylphosphine.

6. The method for preparing the binary metal single-atom catalyst as described in claim 2, characterized in that, In S3, the mass-to-volume ratio of the nickel source, tin source, phosphorus source, nitrogen source and N,N-dimethylformamide is (50~150) mg:(50~150) mg:(50~150) mg:(50~150) mg:(1~10) mL.

7. The method for preparing the binary metal single-atom catalyst as described in claim 2, characterized in that, In S3, the mass ratio of the nickel source to Mil-101-NH2 is (50~150):

500.

8. The method for preparing the binary metal single-atom catalyst as described in claim 2, characterized in that, In S4, the conditions for the first pyrolysis carbonization treatment in the two pyrolysis carbonization treatments are: 1~5℃·min -1 The temperature is increased to 550~650℃ at a certain rate for the first heat preservation.

9. The method for preparing a binary metal single-atom catalyst as described in claim 2, characterized in that, In S4, the conditions for the first pyrolysis carbonization treatment in the two pyrolysis carbonization treatments are: 1~5℃·min -1 The temperature is increased to 800~900℃ at a certain rate for a second heat preservation.

10. The application of the binary metal single-atom catalyst according to claim 1 in the preparation of zinc-air batteries or in the oxygen evolution reaction and carbon dioxide reduction reaction of water electrolysis.

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