An electrocatalyst of mesoporous carbon sphere loaded nickel monatomic atoms controlled by process and preparation method and application thereof

Abstract

This invention belongs to the technical field of electrocatalytic carbon dioxide production of high-value-added products, and discloses an electrocatalyst for supporting nickel (Ni) single atoms on mesoporous carbon spheres by process control of the pore size, as well as its preparation method and application. In this invention, resorcinol and formaldehyde are dissolved in a mixed solution of ethanol, ammonia, and deionized water, and then stirred and annealed at room temperature to obtain mesoporous carbon spheres with different pore sizes. A Ni(OAc)₂·4H₂O ethanol solution is added to the dispersion of the mesoporous carbon spheres, and annealing is performed to obtain the electrocatalyst for supporting nickel single atoms on mesoporous carbon spheres. The high specific surface area and porosity of the mesoporous carbon spheres provide ample space for carbon dioxide (CO₂) transport and adsorption. Simultaneously, the different pore sizes of the mesoporous carbon spheres induce a strain effect at the Ni single-atom sites, thereby promoting the adsorption and conversion efficiency of CO₂, effectively reducing the energy barrier from CO₂ to carbon monoxide (CO), and increasing the CO generation rate. This material exhibits high performance in the range of 100–900 mA cm⁻¹. ‑2 At current densities, it exhibits a CO Faraday efficiency exceeding 90%. This invention significantly improves the performance of CO2 electrochemical CO production by constructing Ni single atoms with different stresses, thereby optimizing the adsorption capacity of Ni for reactant molecules.

Description

Technical Field

[0001] This invention belongs to the technical field of electrocatalytic carbon dioxide preparation of high value-added products, and specifically refers to an electrocatalyst for supporting nickel single atoms on mesoporous carbon spheres by process control, as well as its preparation method and application. Background Technology

[0002] With the increasing severity of global climate change, electrocatalytic reduction of carbon dioxide (CO2RR) has become an important means of addressing carbon emissions and energy issues. CO2RR not only effectively utilizes carbon dioxide but also converts it into valuable chemicals, such as carbon monoxide (CO), which has great potential in subsequent chemical synthesis. Especially under high current density conditions, the selectivity and stability of the CO2 reduction reaction place higher demands on catalyst design.

[0003] Single-atom catalysts (SACs) have become key catalysts in CO2RR research due to their high atom utilization, well-defined active sites, and tunable coordination environments. Among them, Ni single-atom catalysts are currently the most widely used catalysts in the selective CO2-to-CO conversion. However, conventional Ni single-atom catalysts have limited ways to regulate the local electronic structure of the active site, making it difficult to further optimize their adsorption and conversion behavior for key reaction intermediates. At high current densities, existing Ni single-atom catalysts generally suffer from insufficient CO2 mass transfer efficiency, exacerbated hydrogen evolution side reactions, and decreased Faradaic efficiency for the target product. Therefore, it is necessary to provide a new technical solution to improve the catalytic effect of Ni single-atom active sites in electrocatalytic CO2RR by improving their local structure and electronic state.

[0004] Literature indicates that by designing single metal atoms and loading them onto appropriate supports, the kinetics and product selectivity of catalytic reactions can be optimized. For example, introducing strain effects near the single metal atom sites can modulate the electronic structure of the metal center, thereby enhancing catalytic activity. Specifically, the coordination environment of Ni single atoms on curved surfaces differs significantly from that in planar structures, and the Ni-N4 sites on curved surfaces can effectively enhance the activity in CO2 reduction reactions.

[0005] Furthermore, mesoporous carbon materials have become ideal supports for research due to their excellent electrical conductivity, large specific surface area, and tunable pore size. Recent studies have shown that curved structures play an important role in improving the performance of CO2 reduction reaction catalysts. By adjusting the pore size of mesoporous carbon spheres, the strain effect of Ni single atoms can be tuned, thereby optimizing catalytic performance and improving the Faraday efficiency of CO formation. When Ni single atoms are located on curved surfaces, the energy barrier for *COOH formation in the CO2 reduction reaction can be lowered, thus enhancing catalytic activity.

[0006] Therefore, by adjusting the pore size of mesoporous carbon spheres to modulate the strain effect of Ni single atoms, the CO formation efficiency in the CO2 reduction reaction can be significantly improved. Mesoporous carbon spheres with different pore sizes provide different strain effects for Ni single atoms, further optimizing their catalytic performance and thus providing a new approach for the design of catalysts for efficient CO2 reduction reactions. Summary of the Invention

[0007] To address the technical problem of maintaining high CO selectivity under high current density with Ni single atoms, this invention proposes an electrocatalyst with nickel single atoms supported on mesoporous carbon spheres by process control, as well as its preparation method and application.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A method for preparing an electrocatalyst with nickel single atoms supported on mesoporous carbon spheres by controlling the pore size of the support through process control, comprising the following steps:

[0010] (1) Resorcinol (C6H6O2) and formaldehyde (CH2O) are dissolved in ammonia (NH3·H2O), ethanol (EtOH), deionized water and tetrapropoxysilane (C 12 H 28 A solution of O4Si was prepared to obtain mixed solution I.

[0011] (2) The mixed solution I obtained in step (1) was stirred at room temperature, centrifuged, washed, dried and annealed at high temperature to obtain black solid carbon-coated silica particles;

[0012] (3) The black solid carbon-coated silica particles obtained in step (2) are dispersed in a hydrogen fluoride solution, and the silica is removed by etching at room temperature. After centrifugation, washing and drying, mesoporous carbon spheres are obtained.

[0013] (4) Disperse the black solid mesoporous carbon spheres obtained in step (3) in an ethanol solution to obtain mixed solution II; add Ni(OAc)2·4H2O ethanol solution to mixed solution II, stir at room temperature to make Ni ions uniformly adsorbed in the pores of the mesoporous carbon spheres, and dry to obtain black solid.

[0014] (5) The black solid obtained in step (4) is annealed to obtain a mesoporous carbon sphere supported nickel single atom electrocatalyst.

[0015] In step (1) above, the volume ratio of formaldehyde, ammonia, ethanol and deionized water is (1-2):(8-10):(210-220):(30-40):(9-11); the concentration of hydroquinone in mixed solution II is 42-54 g / L.

[0016] In step (2) above, the stirring time at room temperature is 22-28h; the annealing temperature is 650-750 °C and the time is 1-5h.

[0017] In step (3) above, the concentration of hydrogen fluoride solution is 10-30 wt%; the standing time at room temperature is 4-8 h.

[0018] In step (4) above, the concentration of the mesoporous carbon spheres in mixed solution II is 2-3 g / L.

[0019] In step (4) above, the concentration of Ni(OAc)2·4H2O ethanol solution is 0.01-0.02 mol / L; the volume ratio of Ni(OAc)2·4H2O ethanol solution to mixed solution II is (2-8):(20-30).

[0020] Furthermore, in step (4) above, the stirring time at room temperature is 4-8 h; the drying conditions are 60 °C and the time is 3-6 h.

[0021] The annealing temperature in step (5) above is 650-840 °C and the time is 1-4 h.

[0022] Electrocatalysts with nickel single atoms supported on mesoporous carbon spheres prepared using the above-described method feature a hollow structure and abundant surface mesoporous channels. This hollow spherical shell structure possesses both an ultra-high specific surface area, enhancing CO2 diffusion between sites during the reaction, and mesoporous channels of a certain size, effectively controlling the distribution of nickel single atom sites. Because mesoporous carbon spheres of different pore sizes provide different strain effects to the Ni single atoms, the electronic structure of the Ni single atoms is modulated, significantly improving the catalytic activity of Ni single atoms in the CO2 reduction reaction. The strain-effected Ni single atoms further promote the deep reduction of CO2 by optimizing the adsorption of the *CO intermediate, thereby significantly improving the Faraday efficiency of CO formation.

[0023] The above-mentioned electrocatalyst with nickel single atoms supported on mesoporous carbon spheres is used in the carbon dioxide reduction reaction.

[0024] Furthermore, in the above carbon dioxide reduction reaction, the electrocatalyst with nickel single atoms supported on mesoporous carbon spheres operates at 100-900 mA cm⁻¹. -2 At current densities, the Faraday efficiency of carbon monoxide exceeds 90%.

[0025] The beneficial effects of this invention are:

[0026] (1) Strain regulation of the electronic structure of Ni single atoms: By adjusting the pore size of the mesoporous carbon spheres containing Ni single atoms, the strain effect of Ni single atoms was effectively regulated. Mesoporous carbon spheres with different pore sizes caused Ni single atoms to exhibit different strain effects, thereby regulating the electronic structure of Ni and optimizing its catalytic performance. This strain effect made the electronic structure of Ni single atoms more adaptable to the CO2 reduction reaction, thereby improving the activity of the catalyst.

[0027] (2) Strained Ni single atoms optimize the adsorption energy of reactant intermediates: By controlling the electronic structure of Ni single atoms through strain, they can more effectively adsorb reactant intermediates during the reaction. Strained Ni single atoms can optimize the adsorption energy of intermediates (such as *COOH and *CO), reduce the reaction energy barrier, and thus improve the reaction efficiency.

[0028] (3) Excellent CO selectivity and current density: The Ni single-atom catalyst prepared in this invention exhibits excellent CO selectivity at high current densities in the carbon dioxide reduction reaction. (100-900 mA cm⁻¹) -2 Within the current density range, the catalyst exhibits a Faraday efficiency exceeding 90% for CO. Attached Figure Description

[0029] Figure 1 Scanning electron microscope image of Ni-HMCS-5;

[0030] Figure 2 Transmission electron microscope image of Ni-HMCS-5;

[0031] Figure 3 The X-ray diffraction pattern of Ni-HMCS-5;

[0032] Figure 4 The X-ray photoelectron spectrum of Ni-HMCS-5;

[0033] Figure 5 High-resolution X-ray photoelectron spectrum of Ni 2p in Ni-HMCS-5;

[0034] Figure 6 The bar chart shows the Faraday efficiency of Ni-HMCS-5 catalyst.

[0035] Figure 7 The bar chart shows the Faraday efficiency of Ni-HMCS-2 catalyst.

[0036] Figure 8 The bar chart shows the Faraday efficiency of Ni-HMCS-10 catalyst. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] A method for preparing a mesoporous carbon sphere-supported nickel single-atom electrocatalyst, comprising the following steps:

[0039] (1) Resorcinol (C6H6O2) and formaldehyde (CH2O) are dissolved in ammonia (NH3·H2O), ethanol (EtOH), deionized water and tetrapropoxysilane (C 12 H 28 A solution of O4Si was prepared to obtain mixed solution I.

[0040] (2) The mixed solution I obtained in step (1) was stirred at room temperature, centrifuged, washed, dried and annealed at high temperature to obtain black solid carbon-coated silica particles;

[0041] (3) The black solid carbon-coated silica particles obtained in step (2) are dispersed in a hydrogen fluoride solution, and the silica is removed by etching at room temperature. After centrifugation, washing and drying, mesoporous carbon spheres are obtained.

[0042] (4) Disperse the black solid mesoporous carbon spheres obtained in step (3) in an ethanol solution to obtain mixed solution II; add Ni(OAc)2·4H2O ethanol solution to mixed solution II, stir at room temperature to make Ni ions uniformly adsorbed in the pores of the mesoporous carbon spheres, and dry to obtain black solid.

[0043] (5) The black solid obtained in step (4) is annealed to obtain a mesoporous carbon sphere supported nickel single atom electrocatalyst.

[0044] In step (1) above, the volume ratio of formaldehyde, ammonia, ethanol and deionized water is (1-2):(8-10):(210-220):(30-40):(9-11); the concentration of hydroquinone in mixed solution II is 42-54 g / L.

[0045] In step (2) above, the stirring time at room temperature is 22-28 h; the annealing temperature is 650-750 °C and the time is 1-5 h.

[0046] In step (3) above, the concentration of hydrogen fluoride solution is 10-30 wt%; the standing time at room temperature is 4-8 h.

[0047] In step (4) above, the concentration of the mesoporous carbon spheres in mixed solution II is 2-3 g / L.

[0048] In step (4) above, the concentration of Ni(OAc)2·4H2O ethanol solution is 0.01-0.02 mol / L; the volume ratio of Ni(OAc)2·4H2O ethanol solution to mixed solution II is (2-8):(20-30).

[0049] Furthermore, in step (4) above, the stirring time at room temperature is 4-8 h; the drying conditions are 60 °C and the time is 3-6 h.

[0050] The annealing temperature in step (5) above is 650-850 °C and the time is 1-4 h.

[0051] To facilitate a better understanding of the above technical solutions, the following specific embodiments are provided:

[0052] Example 1

[0053] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and tetrapropoxysilane in a volume ratio of 9:210:30:10. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0054] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 24 h.

[0055] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0056] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0057] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0058] (6) Add 5 mL of 0.01 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0059] (7) The product obtained in (6) was annealed at 800 °C for 2 h to finally obtain the electrocatalyst (Ni-HMCS-5) with nickel single atoms supported on mesoporous carbon spheres.

[0060] Scanning electron microscope image of the electrocatalyst with nickel single atoms supported on mesoporous carbon spheres prepared in this embodiment ( Figure 1) and transmission electron microscope images ( Figure 2 As can be seen, the obtained sample is generally a regular sphere with a complete outline. Transmission electron microscopy further reveals that the mesoporous carbon sphere has a distinct hollow shell structure, with a significant contrast difference between the shell and the internal region, indicating its hollow nature. Simultaneously, the shell surface has abundant mesoporous channels with a diameter of approximately 5 nm. This structure is beneficial for increasing the specific surface area of ​​the material and promoting the transport and diffusion of substances during the reaction process.

[0061] X-ray diffraction pattern of the electrocatalyst with nickel single atoms supported on mesoporous carbon spheres prepared in this embodiment ( Figure 3 The results show that the sample exhibits relatively broad and gentle diffraction peaks at approximately 22° and 44°, corresponding to the (002) and (100) crystal planes of low-crystallinity graphitic carbon, respectively, indicating that the main body of the obtained material is a low-crystallinity carbon framework structure. Meanwhile, no obvious characteristic diffraction peaks corresponding to metallic Ni or its related crystals were observed in the spectrum, indicating that no detectable nickel grains or obvious metal agglomeration were formed in the sample. Combined with these results, it can be concluded that nickel species have high dispersibility on the mesoporous carbon sphere support, which is conducive to the formation and stable existence of single-atom sites.

[0062] The X-ray photoelectron spectrum of the mesoporous carbon sphere-supported nickel single-atom electrocatalyst prepared in this embodiment is shown in the figure below. Figure 4 As shown in the full spectrum, the sample exhibits distinct C 1s, N 1s, and Ni 2p characteristic peaks, indicating the presence of carbon, nitrogen, and nickel elements in the composite material. The strong C 1s peak demonstrates a carbon-based framework structure, the presence of the N 1s peak indicates the introduction of a nitrogen coordination environment, and the Ni 2p characteristic peak further confirms the successful loading of nickel species onto the mesoporous carbon sphere support. These results demonstrate that the catalyst obtained in this embodiment is composed of a carbon- and nitrogen-containing support and a nickel active component, providing a compositional basis for the formation of a stable nickel single-atom coordination structure.

[0063] The high-resolution X-ray photoelectron spectroscopy (XPS) of the mesoporous carbon sphere-supported nickel single-atom electrocatalyst prepared in this embodiment is shown in the figure below. Figure 5 As shown in the figure, the sample exhibits a distinct characteristic peak in the Ni 2p region, indicating that nickel species exist in the catalyst in a specific chemical state. Further analysis of the differences in the Ni 2p peak position and shape between Example 1 and the comparative sample reveals a change in the local electronic environment of nickel, suggesting a charge interaction between nickel and adjacent coordinating elements. This interaction indicates that nickel does not exist as simple metal particles, but rather forms a strong interaction with the coordinating atoms in the support, which is beneficial for regulating the electronic structure of the nickel center and enhancing its catalytic performance.

[0064] Example 2

[0065] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and tetrapropoxysilane in a volume ratio of 9:210:30:10. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0066] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 24 h.

[0067] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0068] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0069] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0070] (6) Add 3 mL of 0.01 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0071] (7) The product obtained in (6) was annealed at 750 °C for 2 h to finally obtain the electrocatalyst (Ni-HMCS-5) with nickel single atoms supported on mesoporous carbon spheres.

[0072] Example 3

[0073] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and tetrapropoxysilane in a volume ratio of 9:210:30:11. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0074] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 24 h.

[0075] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0076] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0077] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0078] (6) Add 3 mL of 0.02 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0079] (7) The product obtained in (6) was annealed at 850 °C for 2 h to finally obtain the electrocatalyst (Ni-HMCS-5) with nickel single atoms supported on mesoporous carbon spheres.

[0080] Comparative Example 1

[0081] The preparation method of the mesoporous carbon sphere-supported nickel single-atom electrocatalyst in this comparative example differs from that in Example 1 in that the mesoporous pore size is adjusted by regulating the solution composition, and includes the following steps:

[0082] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and tetrapropoxysilane in a volume ratio of 9:230:10:10. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0083] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 24 h.

[0084] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0085] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0086] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0087] (6) Add 5 mL of 0.01 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0088] (7) The product obtained in (6) was annealed at 800 °C for 2 h to finally obtain the electrocatalyst (Ni-HMCS-2) with nickel single atoms supported on mesoporous carbon spheres.

[0089] Comparative Example 2

[0090] The preparation method of the mesoporous carbon sphere-supported nickel single-atom electrocatalyst in this comparative example differs from that in Example 1 in that the mesoporous pore size is adjusted by regulating the solution composition, and includes the following steps:

[0091] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and tetrapropoxysilane in a volume ratio of 9:180:60:10. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0092] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 24 h.

[0093] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0094] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0095] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0096] (6) Add 5 mL of 0.01 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0097] (7) The product obtained in (6) was annealed at 800 °C for 2 h to finally obtain a mesoporous carbon sphere supported nickel single atom electrocatalyst (Ni-HMCS-10).

[0098] Comparative Example 3

[0099] The preparation method of the carbon-supported nickel single-atom electrocatalyst in this comparative example differs from that in Example 1 in that the residual silicon in the solution is reduced by adjusting the solution composition and extending the template nucleation time, thereby eliminating the mesoporous structure on the prepared carbon shell. The method includes the following steps:

[0100] (1) Dissolve 12 g of resorcinol and 1.68 ml of formaldehyde in a mixed solution of ammonia, ethanol, deionized water and formaldehyde in a volume ratio of 9:230:10:10. The concentration of resorcinol in the resulting mixed solution is 48 g / L.

[0101] (2) Place the mixed solution prepared in step (1) in a beaker and stir at 25 °C for 28 h.

[0102] (3) The precipitate generated in step (2) is centrifuged, washed, and dried at 60 °C for 12 h, and then pyrolyzed at 700 °C in an argon atmosphere to obtain carbon-coated silica particles.

[0103] (4) The carbon-coated silica particles obtained in step (3) are dispersed in a 20 wt% hydrogen fluoride solution, and the silica is etched by standing at room temperature for 7 h. After centrifugation, washing and drying, a black solid (mesoporous carbon spheres) is obtained.

[0104] (5) Disperse 50 mg of the black solid obtained in step (4) in 30 mL of ethanol and ultrasonically disperse it evenly.

[0105] (6) Add 5 mL of 0.01 mol / L Ni(OAc)2·4H2O to the mixed solution obtained in step (5), stir at room temperature for 4 h, and dry at 60 °C for 4 h.

[0106] (7) The product obtained in (6) was annealed at 800 °C for 2 h to finally obtain the electrocatalyst (Ni-HMCS-P) with nickel single atoms supported on mesoporous carbon spheres.

[0107] Comparative Example 4

[0108] Comparative Example 4 used a commercial catalyst, Ag-based powder, which was purchased from the market by Gaoshiruilian.

[0109] Application examples

[0110] The electrocatalytic carbon dioxide reduction performance of Ni-HMCS-5 obtained in Example 1, mesoporous carbon spheres obtained in Comparative Example 1, Ni-HMCS-2 obtained in Comparative Example 1, and Ni-HMCS-10 obtained in Comparative Example 2 were tested and compared as catalysts.

[0111] In the electrocatalytic production of carbon monoxide from carbon dioxide, the working electrode is first prepared. Specifically, 4 mg of catalyst is added to 1 mL of isopropanol, and 10 μL of Nafion® 117 is added as a binder and film-forming aid to ensure that the catalyst particles are more stably loaded onto the conductive substrate surface. After thoroughly mixing the above mixture, a catalyst ink is formed and ultrasonically treated for 1 h to improve the uniformity of catalyst dispersion in the solvent and prevent particle agglomeration, thereby ensuring a uniform distribution of the catalyst layer during subsequent spraying. Subsequently, the prepared catalyst ink is uniformly sprayed onto the surface of carbon paper with dimensions of 2 cm × 4 cm using a spray gun to obtain the catalyst-loaded working electrode, wherein the mass loading of catalyst on the electrode is controlled at 0.5 mg·cm³. -2 .

[0112] The working electrodes prepared above were used to test their electrocatalytic carbon dioxide reduction performance using a chronovoltammetric method. Specifically, under 1 M KOH electrolyte conditions, the catalytic activity and product selectivity of each catalyst in the process of reducing carbon dioxide to carbon monoxide were investigated using a chronovoltammetric method. During the test, the catalytic activity was 100 mA·cm⁻¹. -2 For current density intervals, 100-900 mA·cm -2 The reaction products under different current density conditions were collected and analyzed to systematically evaluate the changes in the electrocatalytic performance of the catalyst from low to high current density. For the analysis of the reaction products, gaseous products were qualitatively and quantitatively detected using gas chromatography, while liquid products were analyzed using... 1 Analysis was performed using 1H NMR. Combining the amount of each product produced and the corresponding electron transfer number, the Faradaic efficiency of different products under various current densities could be calculated, and a current density-Faradaic efficiency histogram was further plotted. By comparing the magnitude of the carbon monoxide Faradaic efficiency of different catalysts under the same current density and its trend with current density, the catalytic activity, product selectivity, and ability to maintain efficient carbon monoxide production under high current density conditions of different samples in the carbon dioxide electroreduction reaction can be intuitively evaluated. Table 1 shows the pore size of the catalysts prepared in different examples and comparative examples, and the specific data on the maximum current density at which the CO Faradaic efficiency is maintained above 90%.

[0113]

[0114] The Faraday efficiency histogram of the electrocatalyst with nickel single atoms supported on mesoporous carbon spheres prepared in this invention is shown below. Figure 6 As shown in the figure. It can be seen from the figure that the Ni-HMCS-5 sample prepared in Example 1 exhibits performance within the range of 100-900 mA cm⁻¹. -2The catalyst maintains a high Faraday efficiency for carbon monoxide across the entire current density range, consistently exceeding 90%, with a maximum value reaching 99%, indicating excellent selectivity for CO electroreduction to CO over a wide current density range. Simultaneously, the low proportion of hydrogen byproducts suggests that the catalyst effectively suppresses hydrogen evolution side reactions, thereby improving the formation efficiency of the target product, CO. The Faraday efficiency histograms for Comparative Example 1 and Comparative Example 2 are shown below. Figure 7 and Figure 8 As shown in the figure, Comparative Example 1 exhibits some carbon monoxide selectivity in the low to medium current density range, but only at 600 mA cm⁻¹. -2 It can maintain a carbon monoxide Faraday efficiency of over 90% within a certain range; when the current density is further increased to 700 mA cm⁻¹ -2 At the above times, its carbon monoxide Faradaic efficiency decreased significantly, while its hydrogen Faradaic efficiency increased rapidly, indicating that the catalyst's selectivity for CO formation was significantly weakened. Comparative Example 2 showed a similar trend, exhibiting high carbon monoxide Faradaic efficiency at lower current densities, but the efficiency gradually decreased with increasing current density, becoming more pronounced at high current densities, and the hydrogen evolution side reaction gradually increased. Furthermore, its performance was compared with Comparative Example 3 (which lacks mesoporous surfaces) and a commercial Ag powder catalyst (Comparative Example 4). The results showed that the maximum current density at which both catalysts maintained a CO Faradaic efficiency above 90% was only 500 mAcm⁻¹. -2 and 400 mA cm -2 In summary, compared with Comparative Examples 1, 2, 3, and 4, the Ni-HMCS-5 prepared in Example 1 maintained a higher carbon monoxide Faraday efficiency and better reaction selectivity over a wider current density range. This indicates that the nickel single-atom catalyst constructed by controlling the pore size of the mesoporous carbon sphere support has superior catalytic activity and high current density adaptability for the electroreduction of carbon dioxide to carbon monoxide.

[0115] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an electrocatalyst with nickel single atoms supported on mesoporous carbon spheres by process control, characterized in that, The steps are as follows: (1) Resorcinol and formaldehyde were dissolved in a solution composed of ammonia, ethanol, deionized water and tetrapropoxysilane to obtain mixed solution I; carbon-coated silica particles were obtained by stirring at room temperature, centrifuging and washing, vacuum drying and annealing in an argon atmosphere. (2) The carbon-coated silica particles obtained in step (1) are placed in a hydrogen fluoride solution to etch and remove the silica. After standing at room temperature, centrifugation, washing and vacuum drying, mesoporous carbon spheres are obtained. (3) Disperse the mesoporous carbon spheres obtained in step (2) in an ethanol solution to obtain mixed solution II; slowly add Ni(OAc)2·4H2O ethanol solution to mixed solution II, stir at room temperature, and dry to obtain solid product; (4) The solid product obtained in step (3) is annealed in an argon atmosphere to obtain a mesoporous carbon sphere supported nickel single-atom electrocatalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the volume ratio of formaldehyde, ammonia, ethanol, deionized water and tetrapropoxysilane is (1-2):(8-10):(210-220):(30-40):(9-11); the concentration of hydroquinone in mixed solution I is 42-54 g / L.

3. The preparation method according to claim 2, characterized in that, In step (1), the stirring time at room temperature is 22-28 h; the annealing temperature is 650-750 °C and the time is 1-5 h.

4. The preparation method according to claim 3, characterized in that, The concentration of the hydrogen fluoride solution in step (2) is 10-30 wt%, and the etching time is 4-10 h.

5. The preparation method according to claim 4, characterized in that, The concentration of the mesoporous carbon spheres in the mixed solution II in step (3) is 2-3 g / L.

6. The preparation method according to claim 5, characterized in that, In step (3), the concentration of the Ni(OAc)2·4H2O ethanol solution is 0.01-0.02 mol / L; the volume ratio of the Ni(OAc)2·4H2O ethanol solution to mixed solution II is (2-8):(20-30).

7. The preparation method according to claim 6, characterized in that, The stirring time at room temperature in step (3) is 4-8 hours.

8. The preparation method according to claim 7, characterized in that, The annealing temperature in step (4) is 650-850 °C and the time is 1-4 h.

9. An electrocatalyst with nickel single atoms supported on mesoporous carbon spheres, characterized in that, The catalyst is prepared using the preparation method according to any one of claims 1-8. The catalyst comprises a hollow mesoporous carbon sphere support and nickel single atoms supported on the support. The mesoporous pore size of the mesoporous carbon spheres is controlled by adjusting the composition of the mixed solution I. The nickel single atoms generate a controllable strain effect due to the pore size difference of the mesoporous carbon spheres.

10. The application of an electrocatalyst with nickel single atoms supported on mesoporous carbon spheres as described in claim 9, characterized in that: This catalyst is used in the carbon dioxide reduction reaction. By adjusting the mesopore size of the mesoporous carbon spheres in the catalyst, the catalytic effect of the carbon dioxide reduction reaction can be changed.

11. The application of the electrocatalyst with mesoporous carbon spheres supporting nickel single atoms according to claim 10, characterized in that, In the carbon dioxide reduction reaction, the electrocatalyst with nickel single atoms supported on mesoporous carbon spheres operates at 100-900 mA cm⁻¹. -2 At current densities, the Faraday efficiency of carbon monoxide exceeds 90%.

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