A kind of HOF derivative thin-walled carbon nanotube supported nickel monatomic catalyst and its preparation method and application

Abstract

The present application relates to the technical field of electrocatalytic reduction of carbon dioxide, and provides a preparation method of HOF-derived thin-wall carbon nanotube supported nickel monatomic catalyst, which comprises the following steps: preparation of Ni-HOF-T precursor; preparation of Ni-HOF-T@SiO2; preparation of Ni-CNT@SiO2; and preparation of HOF-derived thin-wall carbon nanotube supported nickel monatomic catalyst. A layer of SiO2 armor is coated on the surface of the HOF precursor, so that the pyrolysis behavior of the HOF is improved, and the morphology of the thin-wall carbon nanotube is finally maintained. By constructing catalysts with different monatomic coordination structures through different pyrolysis temperatures, the electronic transmission path is optimized, the efficient mass transfer of electrons is promoted, and the electrocatalytic activity and selectivity of the monatomic catalyst are improved. The present application also discloses a HOF-derived thin-wall carbon nanotube supported nickel monatomic catalyst and application thereof.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic reduction of carbon dioxide, and particularly relates to a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, its preparation method, and its application. Background Technology

[0002] Currently, with the rapid advancement of industrialization and urbanization, the continuous increase in carbon dioxide (CO2) emissions has triggered a global ecological crisis, including global warming, frequent extreme weather events, glacial retreat, and ocean acidification. These problems not only threaten natural ecosystems but also pose a severe challenge to the sustainable development of human society. Among numerous carbon resource utilization technologies, electrochemical CO2 reduction reaction (CO2RR) has attracted widespread attention due to its clean and efficient nature, mild reaction conditions, and the ability to be driven by renewable electricity. However, the widespread adoption of CO2RR technology still faces significant challenges. The CO2 molecule has a stable structure and low chemical activity, making it difficult to activate. Furthermore, the reaction involves multiple electron and proton transfer processes, typically requiring high overpotentials, and is accompanied by competition from the hydrogen evolution reaction, resulting in low selectivity for the target product. To achieve efficient CO2RR conversion, developing catalysts with excellent activity, selectivity, and stability is currently the core challenge and breakthrough direction of research.

[0003] Hydrogen-bonded organic frameworks (HOFs) and their derivatives possess excellent catalytic performance due to their highly tunable pore structure and abundant surface active sites. Furthermore, the lightweight and highly ordered structure of HOF materials effectively enhances the adsorption capacity of reactants and promotes charge transfer, making CO2RR a promising template support. Single-atom catalysts (SACs), with their excellent atom utilization and structural controllability, and the ability to significantly improve catalyst activity and selectivity by adjusting the coordination environment of single atoms, show great promise for electrocatalytic CO2 reduction.

[0004] To address the aforementioned technical problems, this invention presents a HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst, its preparation method, and its application. Summary of the Invention

[0005] This invention provides a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, its preparation method, and its application. A SiO2 armor layer is coated on the surface of the HOF precursor to improve the pyrolysis behavior of HOF while maintaining the morphology of the thin-walled carbon nanotubes. By constructing catalysts with different single-atom coordination structures at different pyrolysis temperatures, the electron transport pathway is optimized, promoting efficient electron mass transfer and thus improving the electrocatalytic activity and selectivity of the single-atom catalyst. The catalyst preparation process is simple, the process conditions are easy to control, and it achieves high selectivity for carbon monoxide in the electrocatalytic reduction of carbon dioxide, while also exhibiting a high partial current density.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, comprising the following steps: S1, preparation of Ni-HOF-T precursor: deionized water and anhydrous methanol are mixed to form a mixed solvent, then trimesic acid, melamine and nickel chloride hexahydrate are dissolved in the mixed solvent to obtain a milky white mixed solution; after stirring at room temperature until uniformly dispersed, the mixed solution is transferred to a hydrothermal reactor for hydrothermal reaction, after the reaction is complete, cooled to room temperature, washed several times by centrifugation, and dried in a vacuum oven to finally obtain white Ni-HOF-T precursor powder; S2, preparation of Ni-HOF-T@SiO2: deionized water and anhydrous methanol are mixed to form a mixed solvent, then the Ni-HOF-T precursor powder obtained in step S1 and tetraethyl silicate are dissolved in the mixed solvent to obtain a milky white mixed solution. S1. Preparation of Ni-CNT@SiO2: The white Ni-HOF-T@SiO2 powder from step S2 is thoroughly ground and placed in a tube furnace for high-temperature pyrolysis under an inert atmosphere. After cooling to room temperature, it is then subjected to centrifugation and washing several times, and finally dried in a vacuum oven to obtain white Ni-HOF-T@SiO2 powder. S2. Preparation of Ni-CNT@SiO2: The white Ni-HOF-T@SiO2 powder from step S2 is thoroughly ground and placed in a tube furnace for high-temperature pyrolysis under an inert atmosphere. After cooling to room temperature, black Ni-CNT@SiO2 powder is obtained. S3. Preparation of Ni-CNT@SiO2: The Ni-CNT@SiO2 powder obtained in step S3 is ground and added to a hydrofluoric acid solution for acid washing to remove SiO2. After centrifugation and washing several times with deionized water and anhydrous ethanol, it is then dried in a vacuum oven to obtain HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst.

[0007] Based on the above technical solution, the volume ratio of deionized water to anhydrous methanol in the mixed solvent in steps S1 and S2 is (1~2):(1~4), the molar ratio of trimesic acid to melamine in step S1 is 1:1, and the molar ratio of melamine to nickel chloride hexahydrate is (1~4):1.

[0008] Based on the above technical solution, in steps S1 and S2, the hydrothermal temperature is 120-150℃; the hydrothermal time is 12-24h; the washing solvent is methanol or ethanol; the number of washing cycles is 3-6; the vacuum drying temperature is 50-80℃; and the time is 8-24h.

[0009] Based on the above technical solution, in step S2, the mass ratio of Ni-HOF-T precursor powder to tetraethyl silicate is 1:(5-10), and the ultrasonic treatment time is 15-45 min.

[0010] Based on the above technical solution, in step S3, the pyrolysis temperature is 800-1100℃, the pyrolysis atmosphere is argon, and the pyrolysis time is 2-3 hours.

[0011] Based on the above technical solution, the concentration range of the hydrofluoric acid solution in step S4 is 12% to 48%.

[0012] Based on the above technical solution, in step S4, the pickling time is 12-48 hours, the washing solvent is methanol or ethanol, the number of washing cycles is 3-6, the vacuum drying temperature is 50-80°C, and the time is 8-24 hours.

[0013] Secondly, the present invention provides a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, which is prepared according to the preparation method of the nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes according to any one of the above embodiments.

[0014] Thirdly, the present invention provides the application of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared by the method of preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to any one of the above embodiments in the electroreduction of carbon dioxide to carbon monoxide.

[0015] Based on the above technical solution, the voltage range applied in the process of carbon dioxide electroreduction to carbon monoxide is -0.45 to -1.0V (vs. RHE).

[0016] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0017] 1. This invention is based on hydrogen-bonded organic framework materials and uses a silica-mediated HOF templating method to prepare thin-walled N-doped carbon nanotube catalysts loaded with Ni single atoms. The synthesis process is simple, easy to operate, and easy to promote and use.

[0018] 2. The HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst obtained in this invention has nickel-nitrogen coordination to form catalytic active sites. The ultra-thin tube wall, stable framework, and abundant pores help to increase the exposure of active sites, enabling highly active and selective catalytic reduction of carbon dioxide to carbon monoxide. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other embodiments can be derived from the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the preparation process of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst provided by the present invention.

[0021] Figure 2 These are the X-ray diffraction patterns of the HOF-T precursors prepared in Examples 1-3 and Comparative Example 1 of this invention.

[0022] Figure 3 These are scanning electron microscope images of the HOF-T precursors prepared in Examples 1-3 and Comparative Example 1 of this invention, wherein (a) NiO-HOF-T precursor; (b) Ni 0.3 -HOF-T precursor; (c)Ni 0.5 -HOF-T precursor; (d)Ni 0.7 -HOF-T precursor.

[0023] Figure 4 This is a nitrogen adsorption isotherm diagram of the HOF-T precursors prepared in Example 1 and Comparative Example 1 of this invention.

[0024] Figure 5 This is a pore size distribution diagram of the HOF-T precursors prepared in Example 1 and Comparative Example 1 of the present invention.

[0025] Figure 6 These are the X-ray diffraction patterns of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention.

[0026] Figure 7 These are the Raman spectra of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention.

[0027] Figure 8 These are scanning electron microscope images of HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts obtained in Examples 2 and 4 of this invention, wherein (a) Ni 0.5 -CNT-1000-SACs; (b)Ni 0.5 -CNT-900-SACs.

[0028] Figure 9 These are nitrogen adsorption isotherms of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 2, 4, and 5 of this invention.

[0029] Figure 10 This is a pore size distribution diagram of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 2, 4, and 5 of this invention.

[0030] Figure 11 This is a linear sweep voltammetric (LSV) curve of the nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes prepared in Examples 1-5 and Comparative Example 1 of this invention for the electroreduction of carbon dioxide in an H-type electrolytic cell.

[0031] Figure 12 This is a bar chart showing the Faraday efficiency (FE) of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared in Examples 1-5 and Comparative Example 1 of this invention for the electroreduction of carbon dioxide to carbon monoxide in an H-type electrolytic cell.

[0032] Figure 13 This is a partial current density curve of the electroreduction of carbon dioxide to carbon monoxide in an H-type electrolytic cell using HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and examples:

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0038] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0039] Combination Figure 1 As shown, this invention provides a method for preparing a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, comprising the following steps:

[0040] Preparation of S1, Ni-HOF-T precursor: Deionized water and anhydrous methanol were mixed to form a mixed solvent. Then, pyromellitic acid, melamine and nickel chloride hexahydrate were dissolved in the mixed solvent to obtain a milky white mixed solution. After stirring at room temperature until uniformly dispersed, the mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was complete, it was cooled to room temperature, washed several times by centrifugation, and dried in a vacuum oven to finally obtain white Ni-HOF-T precursor powder.

[0041] S2, Preparation of Ni-HOF-T@SiO2: Deionized water and anhydrous methanol were mixed to form a mixed solvent. Then, the Ni-HOF-T precursor powder obtained in step S1 was dissolved in the mixed solvent with tetraethyl silicate to obtain a milky white mixed solution. After ultrasonication until uniform dispersion, the mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was complete, it was cooled to room temperature, washed several times by centrifugation, and dried in a vacuum oven to finally obtain white Ni-HOF-T@SiO2 powder.

[0042] S3, Preparation of Ni-CNT@SiO2: The white Ni-HOF-T@SiO2 powder from step S2 was thoroughly ground, placed in a tube furnace and pyrolyzed at high temperature under an inert atmosphere, and cooled to room temperature to obtain black Ni-CNT@SiO2 powder;

[0043] S4, HOF-derived thin-walled carbon nanotube supported nickel single-atom catalyst: The Ni-CNT@SiO2 powder obtained in step S3 was ground and then added to hydrofluoric acid solution for acid washing to remove SiO2. After washing several times by centrifugation with deionized water and anhydrous ethanol, it was placed in a vacuum oven to dry, and finally the HOF-derived thin-walled carbon nanotube supported nickel single-atom catalyst was obtained.

[0044] Based on the above technical solution, in steps S1 and S2, the volume ratio of deionized water to anhydrous methanol in the mixed solvent is (1~2):(1~4), the molar ratio of trimesic acid to melamine in step S1 is 1:1, and the molar ratio of melamine to nickel chloride hexahydrate is (1~4):1. Preferably, the volume ratio of deionized water to anhydrous methanol is 1:1.

[0045] Based on the above technical solution, in steps S1 and S2, the hydrothermal temperature is 120–150°C; the hydrothermal time is 12–24 hours; the washing solvent is methanol or ethanol; the number of washing cycles is 3–6; and the vacuum drying temperature is 50–80°C for 8–24 hours. Preferably, the hydrothermal temperature is 150°C, the hydrothermal time is 12 hours, the washing solvent is methanol, the number of washing cycles is 3, and the vacuum drying temperature is 60°C for 12 hours.

[0046] Based on the above technical solution, in step S2, the mass ratio of Ni-HOF-T precursor powder to tetraethyl silicate is 1:(5-10), and the ultrasonic treatment time is 15-45 min. Preferably, the mass ratio of Ni-HOF-T precursor powder to tetraethyl silicate is 1:8, and the ultrasonic treatment time is 30 min.

[0047] Based on the above technical solution, in step S3, the pyrolysis temperature is 800–1100℃, the pyrolysis atmosphere is argon, and the pyrolysis time is 2–3 hours. Preferably, the pyrolysis time is 2 hours.

[0048] Based on the above technical solution, the concentration range of the hydrofluoric acid solution in step S4 is 12% to 48%. Preferably, the concentration of the hydrofluoric acid solution is 12%.

[0049] Based on the above technical solution, in step S4, the pickling time is 12–48 hours, the washing solvent is methanol or ethanol, the number of washing cycles is 3–6, the vacuum drying temperature is 50–80°C, and the time is 8–24 hours. Preferably, the pickling time is 24 hours, the washing solvent is methanol, the number of washing cycles is 3, the vacuum drying temperature is 60°C, and the time is 12 hours.

[0050] Secondly, the present invention provides a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, which is prepared according to the preparation method of the nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes according to any one of the above embodiments.

[0051] Thirdly, the present invention provides the application of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared by the method of preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to any one of the above embodiments in the electroreduction of carbon dioxide to carbon monoxide.

[0052] Based on the above technical solution, the voltage range applied in the process of carbon dioxide electroreduction to carbon monoxide is -0.45 to -1.0V (vs. RHE).

[0053] This invention coats the surface of the HOF precursor with a SiO2 armor layer, thereby improving the pyrolysis behavior of HOF and ultimately maintaining the morphology of thin-walled carbon nanotubes. By constructing catalysts with different single-atom coordination structures at different pyrolysis temperatures, the electron transport pathway is optimized, promoting efficient electron mass transfer and thus improving the electrocatalytic activity and selectivity of the single-atom catalyst. The catalyst preparation process is simple, the process conditions are easy to control, and it can achieve high selectivity for carbon monoxide in the electrocatalytic reduction of carbon dioxide, while also exhibiting a high partial current density.

[0054] Example 1

[0055] This embodiment provides a method for preparing a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, including the following steps:

[0056] S1, using a mixture of 35 ml deionized water and 35 ml anhydrous methanol as a solvent, successively added 0.72 mmol nickel chloride hexahydrate, 2.4 mmol melamine, and 2.4 mmol trimellitic acid to dissolve in the mixed solvent, yielding a milky white mixed solution. After thorough stirring, the mixed solution was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 150 °C for 12 h. After cooling to room temperature, it was transferred to centrifuge tubes, washed three times by centrifugation with anhydrous methanol, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain white Ni. 0.3 -HOF-T precursor powder;

[0057] S2, mix 35 ml of deionized water and 35 ml of anhydrous methanol as a solvent, then add the 500 mg Ni obtained in step S1. 0.3-HOF-T precursor powder and 4g tetraethyl silicate were dissolved in a mixed solvent to obtain a milky white mixed solution. After sonication for 30 min, the mixed solution was transferred to a hydrothermal reactor and subjected to hydrothermal reaction at 150℃ for 12 h. After cooling to room temperature, the solution was transferred to a centrifuge tube, washed three times by centrifugation with anhydrous ethanol, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain white Ni. 0.3 -HOF-T@SiO2 powder;

[0058] S3, the white Ni in step S2 0.3 -HOF-T@SiO2 powder was thoroughly ground and placed in a tube furnace under argon atmosphere and kept at 1000℃ for 2 hours. After cooling to room temperature, black Ni was obtained. 0.3 -CNT-1000@SiO2 powder;

[0059] S4, the Ni obtained in step S3 0.3 - After grinding CNT@SiO2 powder, it was acid-washed in a 12% hydrofluoric acid solution for 24 hours to remove SiO2. Then, it was washed three times by centrifugation with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60℃ for 12 hours to obtain the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst Ni. 0.3 -CNT-1000-SACs.

[0060] Example 2

[0061] The preparation method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the amount of nickel chloride hexahydrate added in step S1 is 1.2 mmol, ultimately obtaining the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst Ni. 0.5 -CNT-1000-SACs.

[0062] Example 3

[0063] The preparation method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the amount of nickel chloride hexahydrate added in step S1 is 1.68 mmol, ultimately obtaining the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst Ni. 0.7 -CNT-1000-SACs.

[0064] Example 4

[0065] The preparation method in this embodiment is the same as that in Example 2, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the pyrolysis temperature of the tubular furnace in step S3 is 900℃, ultimately obtaining the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst Ni. 0.5-CNT-900-SACs.

[0066] Example 5

[0067] The preparation method in this embodiment is the same as that in Example 2, with the identical parts omitted. The difference from Example 1 is that in this embodiment, the pyrolysis temperature of the tubular furnace in step S3 is 1100℃, ultimately obtaining the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst Ni. 0.5 -CNT-1100-SACs.

[0068] Comparative Example 1

[0069] The preparation method of this comparative example is the same as that of Example 1, with the same parts omitted. The difference from Example 1 is that nickel chloride hexahydrate is not added in step S1 in this comparative example, and the HOF-derived thin-walled carbon nanotube supported nickel single-atom catalyst Ni0-CNT-1000-SACs is finally obtained.

[0070] Example 6

[0071] The electroreduction performance of carbon dioxide was tested using the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention.

[0072] The electroreduction performance of carbon dioxide was tested using a three-electrode system. Carbon paper loaded with HOF-derived thin-walled carbon nanotubes and nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 was used as the working electrode, a saturated silver / silver chloride electrode as the reference electrode, and a platinum electrode as the counter electrode. A potassium bicarbonate solution was used as the electrolyte in an H-type electrolytic cell. A constant potential test was performed. Before the test, carbon dioxide gas was introduced to saturate the electrolyte, and the CO2 flow rate was maintained at a constant value. The test lasted for 30 minutes. The potential range during the test was... The gaseous products produced by the reaction were detected by gas chromatography, and the liquid products were detected by nuclear magnetic resonance hydrogen spectroscopy, and the Faraday efficiency was calculated accordingly.

[0073] Figure 1 This is a flowchart of the preparation of HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to the present invention.

[0074] Figure 2 These are the X-ray diffraction patterns of the HOF-T precursors prepared in Examples 1-3 and Comparative Example 1 of this invention. They demonstrate that different molar ratios of nickel chloride hexahydrate (a nickel source) and melamine ligand do not change the crystal structure of the HOF-T precursor, and all yield HOF-T precursors with sharp crystal forms and good crystallinity.

[0075] Figure 3These are scanning electron microscope images of the HOF-T precursors prepared in Examples 1-3 and Comparative Example 1 of this invention. They demonstrate that different molar ratios of nickel chloride hexahydrate (a nickel source) and melamine ligand do not alter the morphological characteristics of the HOF-T precursors, and all yield uniform HOF-T nanotubes.

[0076] Figure 4 and Figure 5 The figures show the nitrogen adsorption isotherm and pore size distribution of the HOF-T precursors prepared in Example 1 and Comparative Example 1 of this invention, respectively. They demonstrate that the nickel-containing and nickel-free HOF-T precursors have mixed pore structures, confirming that the pore structure is predominantly mesoporous with a size of approximately 2.5 nm. Furthermore, the specific surface area of ​​the samples can be calculated using the BET model, and the Ni... 0.5 The specific surface area of ​​-HOF-T showed a significant increase compared to Ni0-HOF-T, indicating that the introduction of metal atoms can effectively improve the specific surface area of ​​the material.

[0077] Figure 6 These are the X-ray diffraction patterns of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention. In the X-ray diffraction patterns, the catalysts prepared in Examples 1-5 and Comparative Example 1 all show only approximately... Two broad peaks appeared at the point, corresponding to the (002) and (101) crystal planes of graphite carbon, respectively, indicating that the obtained catalyst has a high degree of carbonization. No diffraction peaks of Ni species were detected, indicating that the Ni species are in an amorphous state, confirming that Ni exists in the form of single atoms.

[0078] Figure 7 These are the Raman spectra of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention. In the spectra, the catalysts prepared in Examples 1-5 and Comparative Example 1 all have a Raman spectrum of approximately 1580 cm⁻¹. -1 and 1350cm -1 Two broad peaks appeared, corresponding to the G and D peaks of graphitic carbon, respectively. In Examples 1-5, the intensity ratios of the D and G peaks, ID / IG, were all less than 1, indicating that the introduction of nickel could improve the graphitization degree of the material and thus improve its conductivity.

[0079] Figure 8 These are scanning electron microscope (SEM) images of HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts obtained in Examples 2 and 4 of this invention. They demonstrate the protective effect of the silica armor; different pyrolysis temperatures do not alter the morphology of the derived carbon material, which retains the thin-walled carbon nanotube morphology.

[0080] Figure 9 and Figure 10These are nitrogen adsorption isotherms and pore size distribution diagrams of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 2, 4, and 5 of this invention. 0.5 -CNT-900-SACs, Ni 0.5 -CNT-1000-SACs, Ni 0.5 The pore structure of the three CNT-1100-SACs samples was mainly microporous, and Ni 0.5 -CNT-1000-SACs have a large specific surface area, which is beneficial for the contact between the material surface sites and the surrounding environment and for the transport of substances.

[0081] Figure 11 These are the linear sweep voltammetric (LSV) curves of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention for the electroreduction of carbon dioxide in an H-type electrolytic cell. 0.5 -CNT-1000-SACs exhibited the lowest onset potential in CO2-saturated electrolytes, representing the lowest potential in Ni 0.5 -CNT-1000-SACs exhibit the lowest reaction energy barrier and the highest catalytic activity for CO2RR, which is beneficial for improving the energy efficiency of the cathode reaction.

[0082] Figure 12 This is a bar chart showing the Faraday efficiency of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared in Examples 1-5 and Comparative Example 1 of this invention for the electroreduction of carbon dioxide to carbon monoxide in an H-type electrolytic cell. 0.5 -CNT-1000-SACs achieved a Faraday efficiency of over 90% for carbon monoxide products over a wide potential range of -0.7 to -1.0 V vs. RHE, with a Faraday efficiency as high as 98% at -0.75 V vs. RHE, which is higher than other embodiments, and exhibits extremely excellent selectivity for CO products.

[0083] Figure 13 This is a partial current density curve of the electroreduction of carbon dioxide to carbon monoxide in an H-type electrolytic cell using HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalysts prepared in Examples 1-5 and Comparative Example 1 of this invention. 0.5 -CNT-1000-SACs exhibit the highest partial current density, exceeding that of other embodiments, and thus possess the best catalytic performance.

[0084] In summary, the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared by this invention has ultra-thin walls, a stable framework, and abundant pores, which helps to increase the exposure of active sites and enables highly active and selective catalytic reduction of carbon dioxide to carbon monoxide.

[0085] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, characterized in that, Includes the following steps: Preparation of S1, Ni-HOF-T precursor: Deionized water and anhydrous methanol were mixed to form a mixed solvent. Then, pyromellitic acid, melamine and nickel chloride hexahydrate were dissolved in the mixed solvent to obtain a milky white mixed solution. After stirring at room temperature until uniformly dispersed, the mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was complete, it was cooled to room temperature, washed several times by centrifugation, and dried in a vacuum oven to finally obtain white Ni-HOF-T precursor powder. S2, Preparation of Ni-HOF-T@SiO2: Deionized water and anhydrous methanol were mixed to form a mixed solvent. Then, the Ni-HOF-T precursor powder obtained in step S1 was dissolved in the mixed solvent with tetraethyl silicate to obtain a milky white mixed solution. After ultrasonication until uniform dispersion, the mixed solution was transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was complete, it was cooled to room temperature, washed several times by centrifugation, and dried in a vacuum oven to finally obtain white Ni-HOF-T@SiO2 powder. S3, Preparation of Ni-CNT@SiO2: The white Ni-HOF-T@SiO2 powder from step S2 was thoroughly ground, placed in a tube furnace and pyrolyzed at high temperature under an inert atmosphere, and cooled to room temperature to obtain black Ni-CNT@SiO2 powder; S4, HOF-derived thin-walled carbon nanotube supported nickel single-atom catalyst: The Ni-CNT@SiO2 powder obtained in step S3 was ground and then added to hydrofluoric acid solution for acid washing to remove SiO2. After washing several times by centrifugation with deionized water and anhydrous ethanol, it was placed in a vacuum oven to dry, and finally the HOF-derived thin-walled carbon nanotube supported nickel single-atom catalyst was obtained.

2. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, In steps S1 and S2, the volume ratio of deionized water to anhydrous methanol in the mixed solvent is (1-2):(1-4), the molar ratio of trimesic acid to melamine in step S1 is 1:1, and the molar ratio of melamine to nickel chloride hexahydrate is (1-4):

1.

3. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, In steps S1 and S2, the hydrothermal temperature is 120–150°C; the hydrothermal time is 12–24 h; the washing solvent is methanol or ethanol; the number of washing cycles is 3–6; and the vacuum drying temperature is 50–80°C for 8–24 h.

4. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, In step S2, the mass ratio of Ni-HOF-T precursor powder to tetraethyl silicate is 1:(5-10), and the ultrasonic treatment time is 15-45 min.

5. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, In step S3, the pyrolysis temperature is 800–1100℃, the pyrolysis atmosphere is argon, and the pyrolysis time is 2–3 hours.

6. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, The concentration range of the hydrofluoric acid solution in step S4 is 12% to 48%.

7. The method for preparing the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst according to claim 1, characterized in that, In step S4, the pickling time is 12-48 hours, the washing solvent is methanol or ethanol, the number of washing cycles is 3-6, the vacuum drying temperature is 50-80°C, and the time is 8-24 hours.

8. A nickel single-atom catalyst supported on HOF-derived thin-walled carbon nanotubes, characterized in that, The HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst was prepared according to any one of claims 1 to 7.

9. The application of the HOF-derived thin-walled carbon nanotube-supported nickel single-atom catalyst prepared by the method according to any one of claims 1 to 7 in the electroreduction of carbon dioxide to carbon monoxide.

10. The application according to claim 9, characterized in that, The voltage range applied in the electroreduction of carbon dioxide to carbon monoxide is -0.45 to -1.0 V vs. RHE.

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