Ni nanoparticle and ni monatomic synergistic catalyst, and preparation method and application thereof

Abstract

The application belongs to the field of electrocatalytic materials and energy conversion technology, and particularly relates to a Ni nanoparticle and Ni monatomic synergistic catalyst as well as a preparation method and application thereof. The preparation steps of the Ni nanoparticle and Ni monatomic synergistic catalyst include: mixing a soluble zinc salt, a soluble nickel salt and an organic ligand in water, then mixing with a solution containing polydopamine, and sequentially performing light-shield aging, drying and pyrolysis to obtain the Ni nanoparticle and Ni monatomic synergistic catalyst. The application provides a strategy of combining a two-dimensional ZIF-L precursor with PDA bifunctional modification, in the catalyst preparation process, the introduced PDA simultaneously acts as a structure directing agent and a metal size control agent, realizing the synergistic coexistence of Ni monatomic and nanoparticles, precise size control and construction of a hollow leaf-shaped carbon-based carrier. By utilizing the hydrogen overflow synergistic effect between the Ni nanoparticle and the Ni monatomic, the catalytic activity, selectivity and stability of the electrocatalytic reduction of CO2 are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials and energy conversion technology, specifically relating to a Ni nanoparticle and Ni single-atom synergistic catalyst, its preparation method and application. Background Technology

[0002] With the increasing prominence of the global energy crisis and environmental problems, the conversion and utilization of carbon dioxide (CO2) has become an important way to mitigate the greenhouse effect and achieve the "dual carbon" goal. The electrochemical reduction reaction of CO2 (CO2RR) can convert CO2 into valuable chemicals such as CO, methane, and methanol, combining environmental friendliness and energy sustainability, and is currently a research hotspot in the field of catalysis. Among these, the reduction of CO2 to CO is one of the reaction pathways with the greatest industrial potential, possessing advantages such as single product, high Faraday efficiency, and low energy consumption.

[0003] Metal-nitrogen-carbon (MNC) single-atom catalysts, especially nickel-based nitrogen-carbon materials (Ni-NC), have attracted much attention due to their excellent selectivity for the conversion of CO2 to CO. Their active centers (Ni-N...) x Ni single-atom catalysts can preferentially adsorb and activate CO2, while suppressing water adsorption to some extent, thus effectively suppressing the hydrogen evolution reaction (HER) and improving CO selectivity. However, the high selectivity (close to 100%) of traditional Ni single-atom catalysts is usually limited to a narrow potential window (generally less than 1.0V), which is difficult to maintain at industrial-grade current densities, severely limiting their practical applications. The reason for this is that the reduction of CO2 to CO is a proton-coupled electron transfer process, in which the formation of the ·COOH intermediate is often the rate-determining step, requiring a sufficient supply of protons. At higher overpotentials, single-atom sites often face insufficient proton supply, leading to slower reaction kinetics, which in turn allows HER to dominate, reducing catalytic selectivity and activity.

[0004] In recent years, the hydrogen spillover effect has provided a new approach to solving this problem—active hydrogen (·H) generated on metal nanoclusters with strong water dissociation capabilities can migrate to nearby single-atom sites that are weakly adsorbed for ·H but strongly adsorbed for CO2, opening up additional hydrogen source channels for the protonation process of CO2. However, achieving the controllable construction and stable existence of such multi-sized active centers (single atoms, nanoparticles) remains a challenge: during high-temperature pyrolysis, metal atoms tend to migrate and aggregate, making it difficult to precisely control the morphology of Ni and achieve synergistic coexistence between single atoms and nanoparticles; at the same time, commonly used ZIF precursors are prone to structural collapse and pore shrinkage during pyrolysis, leading to a reduction in active sites and limited mass transfer, further restricting catalytic performance.

[0005] Furthermore, Zn-CO2 batteries, as a novel energy storage and conversion device, can combine CO2 reduction reactions with electrical energy storage, possessing both CO2 conversion and energy supply functions. However, their performance heavily depends on the catalytic activity and stability of the cathode catalyst. Currently reported Zn-CO2 battery cathode catalysts generally suffer from low power density and short cycle life, making it difficult to meet practical application requirements. Summary of the Invention

[0006] To address the aforementioned technical bottlenecks, this invention provides a Ni nanoparticle-Ni single-atom synergistic catalyst, its preparation method, and its application. This invention proposes a preparation strategy using a two-dimensional Zn-based metal-organic framework (ZIF-L) as a precursor and polydopamine (PDA) as a multifunctional modifier (structure-directing agent + metal size regulator) to construct a hollow leaf-shaped carbon-based catalyst synergistically combining Ni nanoparticles and Ni single atoms. Through the synergistic effect of hydrogen spillover from dual active sites, it overcomes the kinetic bottleneck of CO2 reduction reaction (CO2RR) and simultaneously improves the overall performance of Zn-CO2 batteries, providing a new solution for the design and application of high-performance CO2 reduction electrocatalysts.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a method for preparing a Ni nanoparticle and Ni single-atom synergistic catalyst, comprising the following steps: Soluble zinc salt, soluble nickel salt and organic ligand are mixed in water, and then mixed with a solution containing polydopamine. The mixture is then subjected to light-protected aging, drying and pyrolysis in sequence to obtain the Ni particle and Ni single atom synergistic catalyst.

[0008] This invention yields a hollow leaf-shaped carbon-based catalyst with synergistic Ni nanoparticles and Ni single atoms. Using carbon as a support, the catalyst exhibits a hollow leaf-shaped structure, with Ni nanoparticles (NPS) and Ni single atoms (SA) uniformly dispersed on the support. The Ni single atoms are arranged in a Ni-N configuration. x It exists in the form of an active site.

[0009] There is a synergistic effect of hydrogen spillover between Ni nanoparticles and Ni single atoms. Ni nanoparticles dissociate water to generate active hydrogen, which migrates to Ni single atom sites, promoting the protonation of CO2 to form the ·COOH intermediate and accelerating the CO2 reduction reaction kinetics. At the same time, Ni nanoparticles transfer electrons to Ni single atom sites, regulate the electronic structure of Ni, enhance the strength of Ni-N bonds, inhibit the electrochemical dissolution of Ni, and improve the stability of the catalyst.

[0010] Hollow leaf-shaped carbon-based supports, serving as the core framework of catalysts, exhibit unique value in catalytic reactions due to their distinctive layered hollow structure and abundant nitrogen coordination sites. Their high specific surface area and well-defined pore distribution make them not only a stable loading platform for Ni species but also crucial channels for mass transfer. The hierarchical pore structure of the hollow leaf-shaped structure significantly enhances the mass transfer efficiency of the catalyst, providing ample space for CO2 molecule adsorption, activation, and product desorption. In catalytic reactions, the hollow structure acts as a mass transfer channel, reducing the resistance to contact between CO2 molecules and active sites while mitigating the obstruction of active sites by product accumulation, thus ensuring the continuous and efficient conduction of the catalytic reaction.

[0011] Polydopamine (PDA), as the key modifier in this invention, possesses both structure-directing and metal size-regulating functions. The catechol and amino functional groups in its molecule can interact with Ni. 2+ It forms stable coordination bonds while competing for coordination with the ZIF-L precursor. This dual effect enables it not only to suppress structural collapse and Ni species aggregation during ZIF-L pyrolysis, but also to precisely control the size of Ni species, achieving a controllable distribution from single atoms and clusters to nanoparticles. The carbonization products of PDA can form a dense carbon shell, encapsulating the surface of the carbon-based support, further enhancing the structural stability of the support; simultaneously, the nitrogen generated during PDA carbonization can coordinate with Ni atoms to form Ni-N. x Active sites enhance the stability and catalytic activity of Ni single atoms. This synergistic regulation strategy of "structure-size-activity" provides an important approach for the design of high-performance CO2 reduction electrocatalysts.

[0012] This invention uses two-dimensional ZIF-L as a precursor and combines it with the bifunctional modification effect of PDA. Utilizing the competitive coordination and chelation properties of PDA, it achieves the construction of hollow leaf-like structures and precise control of Ni species size. Further, through high-temperature pyrolysis, the Ni particles and Ni single-atom synergistic catalyst are obtained, denoted as Ni. NPS&SA -NC-L x On the one hand, the introduction of PDA can effectively suppress structural shrinkage and collapse during the ZIF-L pyrolysis process, forming a stable hollow leaf-shaped carbon-based support and increasing the specific surface area and pore volume of the catalyst; on the other hand, PDA and Ni 2+ The coordination effect of PDA can inhibit the migration and aggregation of Ni atoms, achieving the synergistic coexistence of Ni single atoms and nanoparticles. The synergistic effect of hydrogen spillover between the two can overcome the kinetic bottleneck of CO2 electroreduction. Simultaneously, the carbonization products of PDA can introduce abundant nitrogen elements, further optimizing the electronic structure of the catalyst and improving its catalytic performance.

[0013] Optionally, the soluble zinc salt is zinc nitrate; the soluble nickel salt is nickel nitrate; and the organic ligand is 2-methylimidazole.

[0014] Preferably, the molar ratio of Zn to the organic ligand in the soluble zinc salt is 1:16.15.

[0015] Preferably, the molar ratio of Zn in the soluble zinc salt to Ni in the soluble nickel salt is 3.2~12.8:1.

[0016] Preferably, the solvent in the polydopamine-containing solution is an equal volume mixture of anhydrous ethanol and water.

[0017] Preferably, the polydopamine-containing solution also contains ammonia.

[0018] Preferably, the temperature for light-protected aging is 30~50℃, and the time is 20~28h.

[0019] Preferably, the drying is vacuum drying.

[0020] Preferably, the pyrolysis is carried out under an inert atmosphere, with a pyrolysis temperature of 850~1000℃, a holding time of 1~3h, and a heating rate of 5~6℃ / min.

[0021] The second technical solution of the present invention provides a Ni nanoparticle and Ni single atom synergistic catalyst prepared according to the above-mentioned preparation method of Ni nanoparticle and Ni single atom synergistic catalyst.

[0022] The third technical solution of the present invention provides an application of the above-mentioned Ni nanoparticles and Ni single-atom synergistic catalyst in the catalytic electrochemical reduction reaction of CO2.

[0023] The fourth technical solution of the present invention provides an application of the above-mentioned Ni nanoparticles and Ni single-atom synergistic catalyst in the preparation of Zn-CO2 batteries.

[0024] The beneficial technical effects of the present invention are as follows: This invention provides a strategy combining two-dimensional ZIF-L precursors with bifunctional PDA modification. During catalyst preparation, the introduced PDA simultaneously acts as a structure-directing agent and a metal size regulator, achieving the synergistic coexistence of Ni single atoms and nanoparticles, precise size control, and the construction of hollow leaf-shaped carbon-based supports. The PDA used in this invention does not introduce additional residual substances during preparation; its carbonization products can also serve as a carbon source supplement, improving the conductivity and structural stability of the carbon-based support. This enables the controllable preparation of high-performance dual-active-site catalysts, significantly enhancing catalytic performance and overall battery performance, and has broad application prospects in energy conversion devices such as electrocatalytic CO2 resource utilization and Zn-CO2 batteries. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart (a) shows the preparation process of Ni nanoparticles and Ni single-atom synergistic catalysts in Example 1. NPS&SA -NC-L 0.5 SEM image (b), Ni prepared in Comparative Example 1 NPS&SA SEM image and pore size distribution of -NC-L-0.5 (c), Ni prepared in Example 1 NPS&SA -NC-L 0.5 HRTEM image (d), Ni prepared in Example 1 NPS&SA -NC-L 0.5 HAADF-STEM image (e), Ni prepared in Example 1 NPS&SA -NC-L 0.5 The full-element mapping (f) and the single-element mapping (h~h3).

[0027] Figure 2 LSV curves (a) of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 under Ar atmosphere and saturated CO2, FE CO Figure (b), local current density plot (c), transition frequency (TOF) plot at different applied potentials (d), Tafel slope plot (e), and electrochemical double-layer capacitance measurement (ESCA) plot (f).

[0028] Figure 3 Ni prepared in Example 1 NPS&SA -NC-L 0.5 Stability test results of the catalyst after 30 h of continuous electrolysis at -0.58 V.

[0029] Figure 4 HER LSV curves (a) and corresponding Tafel slope plots (b) of the catalysts prepared for Examples 1-3 and Comparative Examples 1-3 in 1M KOH solution. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0031] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0032] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] Unless otherwise specified, room temperature in this invention refers to a temperature of 20±10℃.

[0036] The weight-average molecular weight of the PDA used in this embodiment of the invention is 189.64.

[0037] Example 1 A method for preparing a Ni nanoparticle-Ni single-atom synergistic catalyst, comprising the following steps: Step 1: Weigh 0.5 g of polydopamine (PDA) and dissolve it in a mixed solution of 20 mL distilled water and 20 mL anhydrous ethanol. Add 300 μL of 25% ammonia solution and sonicate for 10 min until the solution turns a uniform rose-red color. Set aside for later use. Step 2: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 90.08 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 3: Quickly inject solution A into solution B, and simultaneously add the PDA solution prepared in step 1. Use magnetic stirring to continuously stir at 600 rpm, and age in a constant temperature water bath at 40 ℃ in the dark for 24 h. Then, centrifuge at 8000 rpm for 10 min to collect the product, and wash it three times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. Dry the washed product in a vacuum environment at 60 ℃ for 12 h to obtain the catalyst precursor. Step 4: Place the catalyst precursor obtained in Step 3 in a tube furnace. First, continuously purge the furnace with nitrogen gas for 30 min to remove air. The nitrogen flow rate is controlled at 50 mL / min. Then, under a nitrogen atmosphere, heat the catalyst to 1000 °C at a heating rate of 5 °C / min, hold for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni nanoparticle and Ni single-atom synergistic catalyst (denoted as Ni). NPS&SA -NC-L 0.5 ).

[0038] Example 2 A method for preparing a Ni nanoparticle-Ni single-atom synergistic catalyst, comprising the following steps: Step 1: Weigh 0.5 g of polydopamine (PDA) and dissolve it in a mixed solution of 20 mL distilled water and 20 mL anhydrous ethanol. Add 300 μL of 26% ammonia solution and sonicate for 12 min until the solution turns a uniform rose-red color. Step 2: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 45.04 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 3: Quickly inject solution A into solution B, and simultaneously add the PDA solution prepared in step 1. Use magnetic stirring to continuously stir at 600 rpm, and age in a constant temperature water bath at 50 ℃ in the dark for 24 h. Then, centrifuge at 8000 rpm for 10 min to collect the product, and wash it four times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. Dry the washed product in a vacuum environment at 60 ℃ for 12 h to obtain the catalyst precursor. Step 4: Place the catalyst precursor obtained in Step 3 in a tube furnace. First, continuously purge the furnace with nitrogen gas for 30 min to remove air. The nitrogen flow rate is controlled at 80 mL / min. Then, under a nitrogen atmosphere, heat the catalyst to 1000 °C at a heating rate of 5 °C / min, hold for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni nanoparticle and Ni single-atom synergistic catalyst (denoted as Ni).NPS&SA -NC-L 0.25 ).

[0039] Example 3 A method for preparing a Ni nanoparticle-Ni single-atom synergistic catalyst, comprising the following steps: Step 1: Weigh 0.5 g of polydopamine (PDA) and dissolve it in a mixed solution of 20 mL distilled water and 20 mL anhydrous ethanol. Add 300 μL of 28% ammonia solution and sonicate for 15 min until the solution turns a uniform rose-red color. Set aside for later use. Step 2: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 180.16 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 3: Quickly inject solution A into solution B, and simultaneously add the PDA solution prepared in step 1. Stir continuously at 600 rpm using magnetic stirring, and age for 24 h in a constant temperature water bath at 40 ℃ in the dark. Then, collect the product by centrifugation at 8000 rpm for 10 min, and wash it four times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. Dry the washed product in a vacuum environment at 60 ℃ for 12 h to constant weight to obtain the catalyst precursor. Step 4: Place the catalyst precursor obtained in Step 3 in a tube furnace. First, continuously purge the furnace with nitrogen gas for 30 min to remove air. The nitrogen flow rate is controlled at 100 mL / min. Then, under a nitrogen atmosphere, heat the furnace to 1000 °C at a heating rate of 5 °C / min, hold for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni nanoparticle and Ni single-atom synergistic catalyst (denoted as Ni). NPS&SA -NC-L1).

[0040] Comparative Example 1 A method for preparing a Ni-based carbon catalyst (without PDA addition, and without PDA bifunctional modulation) is as follows: Step 1: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 90.08 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 2: Solution A was rapidly injected into solution B and stirred continuously at 600 rpm. The mixture was aged for 24 h in a constant temperature water bath at 40 ℃ under dark conditions. Subsequently, the product was collected by centrifugation at 8000 rpm for 10 min. The product was washed four times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. The washed product was dried in a vacuum environment at 60 ℃ for 12 h to constant weight to obtain the catalyst precursor. Step 3: Place the catalyst precursor obtained in Step 2 in a tube furnace, and continuously purge the furnace with nitrogen gas for 30 min to purge air. The nitrogen gas flow rate is controlled at 80 mL / min. Then, under a nitrogen atmosphere, heat the catalyst to 1000 °C at a heating rate of 5 °C / min, hold at that temperature for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni-based carbon catalyst (denoted as Ni). SA -NC-L-0.5).

[0041] Comparative Example 2 A method for preparing a Ni-based carbon catalyst (without PDA addition, and without PDA bifunctional modulation) is as follows: Step 1: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 45.04 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 2: Solution A was rapidly injected into solution B and stirred continuously at 600 rpm. The mixture was aged for 24 h in a constant temperature water bath at 40 ℃ under dark conditions. Subsequently, the product was collected by centrifugation at 8000 rpm for 10 min. The product was washed four times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. The washed product was dried in a vacuum environment at 60 ℃ for 12 h to constant weight to obtain the catalyst precursor. Step 3: Place the catalyst precursor obtained in Step 2 in a tube furnace, and continuously purge the furnace with nitrogen gas for 30 min to purge air. The nitrogen gas flow rate is controlled at 80 mL / min. Then, under a nitrogen atmosphere, heat the catalyst to 1000 °C at a heating rate of 5 °C / min, hold at that temperature for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni-based carbon catalyst (denoted as Ni). SA -NC-L-0.25).

[0042] Comparative Example 3 A method for preparing a Ni-based carbon catalyst (without PDA addition, and without PDA bifunctional modulation) is as follows: Step 1: Dissolve 0.59 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 180.16 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 100 mL of distilled water and stir until completely dissolved to obtain solution A; dissolve 2.63 g of 2-methylimidazole in 100 mL of deionized water and stir until completely dissolved to obtain solution B; Step 2: Solution A was rapidly injected into solution B and stirred continuously at 600 rpm. The mixture was aged for 24 h in a constant temperature water bath at 40 ℃ under dark conditions. Subsequently, the product was collected by centrifugation at 8000 rpm for 10 min. The product was washed four times alternately with distilled water and anhydrous ethanol to remove unreacted reagents. The washed product was dried in a vacuum environment at 60 ℃ for 12 h to constant weight to obtain the catalyst precursor. Step 3: Place the catalyst precursor obtained in Step 2 in a tube furnace, and continuously purge the furnace with nitrogen gas for 30 min to purge air. The nitrogen gas flow rate is controlled at 80 mL / min. Then, under a nitrogen atmosphere, heat the catalyst to 1000 °C at a heating rate of 5 °C / min, hold at that temperature for 2 h, and allow it to cool naturally to room temperature to obtain a black powdery Ni-based carbon catalyst (denoted as Ni). NPS&SA -NC-L-1).

[0043] The catalyst samples prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to a series of characterization and performance tests. The test results are as follows: 1. Catalyst Synthesis and Structural Characterization: Flowchart (a) of the preparation of Ni nanoparticles and Ni single-atom synergistic catalyst in Example 1, and Ni prepared in Example 1. NPS&SA -NC-L 0.5 SEM image (b), Ni prepared in Comparative Example 1 NPS&SA SEM image and pore size distribution of -NC-L-0.5 (c), Ni prepared in Example 1 NPS&SA -NC-L 0.5 HRTEM image (d), Ni prepared in Example 1 NPS&SA -NC-L 0.5 HAADF-STEM image (e), Ni prepared in Example 1 NPS&SA -NC-L 0.5 The full-element mapping (f) and single-element mappings (h~h3) are shown in [reference]. Figure 1 .

[0044] Figure 1 Figure a shows the Ni prepared in the example. NPS&SA -NC-L 0.5 The synthesis process of catalysts; Figure 1 The results in b indicate that the Ni prepared by introducing polydopamine (PDA)NPS&SA -NC-L 0.5 It better preserved the lamellar structure of the ZIF-L precursor; Figure 1 The results of c show that the comparison sample Ni without added PDA NPS&SA -NC-L-0.5 all exhibited structural collapse during high-temperature treatment. Further analysis using high-resolution transmission electron microscopy images (…) Figure 1 From d), we can find that Ni NPS&SA -NC-L 0.5 The nanoparticles are uniformly distributed on the graphite carbon support. HAADF-STEM image ( Figure 1 In (e) Ni prepared in Example 1 can be observed NPS&SA -NC-L 0.5 The catalyst exhibits clear lattice fringes with a spacing of 0.207 nm, corresponding to the (111) crystal plane of metallic Ni; the corresponding energy-dispersive X-ray spectroscopy (EDS) elemental distribution map ( Figure 1 The results from f, h, h1, h2, and h3 further confirm that the four elements O, Ni, C, and N exhibit a uniform spatial distribution in the material.

[0045] In addition, X-ray powder diffraction data of each sample showed that the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 had two broadened carbon diffraction peaks at around 26° and 44°, respectively, corresponding to the (002) and (100) crystal planes of graphitic carbon, indicating that the carbon matrix has an amorphous structure, which is due to the discontinuous or highly disordered carbon network structure.

[0046] 2. Evaluation of the catalyst's CO2 electroreduction performance: For the H-type battery, the catalyst ink consisted of 5 mg of catalyst powder, 20 μL of Nafion solution (5%), and 230 μL of isopropanol (as solvent), and was ultrasonically dispersed for at least 1 h to ensure uniform mixing. Subsequently, 50 μL of the catalyst ink was dropped onto carbon paper (SGL SIGRACET 28BC) to achieve a 1 mg·cm⁻¹ concentration. -2 The catalyst loading was determined. Electrochemical measurements of the H-type battery were performed using a three-electrode system. The anode and cathode chambers were separated by a pre-activated proton exchange membrane (Nafion 117), and the electrolyte was a 0.5 M KHCO3 solution. A platinum plate (1 × 1 cm²) was used. 2 An Ag / AgCl electrode (saturated with 3 M KCl solution) was used as the counter electrode and reference electrode, respectively. All measured potentials were converted to the reversible hydrogen electrode (RHE) scale using the formula: E RHE = E AgCl + 0.0591 × pH + 0.210 V, where E AgClThe potential for Ag / AgCl is given. All electrodes are connected to an electrochemical workstation (Cortest CS310M). Before electrolysis, the electrolyte is prepared at a flow rate of 50 mL / min. -1 The electrolyte was purified and saturated using high-purity CO2 gas. A flow rate of 20 mV·s was adopted. -1 The scan rate was measured using linear sweep voltammetry (LSV). The CO2 reduction reaction (CO2RR) performance of the catalyst at different potentials was evaluated using galvanostatic method (CA).

[0047] LSV curves (a) of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 under Ar atmosphere and saturated CO2, FE CO Figure (b), local current density plot (c), transition frequency (TOF) plot at different applied potentials (d), Tafel slope plot (e), ESCA plot of electrochemical double-layer capacitance measurement (f) Figure 2 .

[0048] like Figure 2 As shown in Figure a, in a CO2-saturated 0.5 M KHCO3 electrolyte, Ni NPS&SA -NC-L 0.5 The catalyst exhibits the highest current density and the lowest onset potential. CO Faraday efficiency ( Figure 2 As shown in b), Ni NPS&SA -NC-L 0.5 It exhibited the highest CO selectivity at all test potentials. CO partial current density ( Figure 2 c) indicates that Ni NPS&SA -NC-L 0.5 It exhibits optimal catalytic current across the entire potential range. The calculated TOF ( Figure 2 (d) reveals its astonishing intrinsic activity: Ni NPS&SA -NC-L 0.5 TOF at -1.18 V CO Up to 103413 h -1 Ni NPS&SA -NC-L 0.5 The Tafel slope is the lowest, at 62 mV·dec. -1 ( Figure 2 e). Ni NPS&SA -NC-L 0.5 The electrochemically active surface area (ECSA) is 45 mF·cm. -2 ( Figure 2 (f)

[0049] 3. Catalyst stability test: After loading the catalyst onto carbon paper, chronoamperometry (CA) was used for continuous electrolysis at a constant potential of -0.58 V vs. RHE. During electrolysis, the retention of activity was assessed by monitoring changes in current density, and the Faradaic efficiency (FE) of CO was calculated by periodically detecting gaseous products using online gas chromatography (GC). CO )stability.

[0050] Ni prepared in Example 1 NPS&SA -NC-L 0.5 The stability test results of the catalyst under continuous electrolysis at -0.58 V for 30 h are shown in the figure. Figure 3 .

[0051] like Figure 3 As shown, the durability of the catalyst was evaluated using a constant potential electrolysis system (-0.58 V vs. RHE, for 30 h). Ni NPS&SA -NC-L 0.5 Maintaining over 90% FE throughout the entire testing process CO The current density shows almost no decay, demonstrating excellent operational stability.

[0052] The HER LSV curves (a) and corresponding Tafel slope plots (a) of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 in 1M KOH solution are shown in Figure 1. Figure 4 LSV testing of alkaline HER requires a three-electrode system, using a rotating disk electrode (RDE, commonly 1600 rpm) as the working electrode. The test is conducted in freshly prepared 1 M KOH electrolyte. Before testing, N2 / Ar must be bubbled through the electrolyte for thorough deoxygenation, and the electrode should be activated using cyclic voltammetry. LSV scan parameters are generally set to a scan rate ≤10 mV / s (5 mV / s recommended), and the potential range relative to the reversible hydrogen electrode (RHE) is typically 0 to -0.8 V.

[0053] To further evaluate the reaction kinetics of water activation and protonation, Ni was tested. NPS&SA -NC-L 0.5 and Ni SA- HER performance of NC-L-0.5 Figure 4 This is confirmed in (a) of the paper. NPS&SA -NC-L 0.5 and Ni SA The polarization curves of Ni-L-0.5 on HER indicate that Ni NPS&SA -NC-L has a lower overpotential than Ni SA -NC-L. Ni NPS&SA -NC-L 0.5 and Ni SAThe Tafel slopes for -NC-L-0.5 are 236.6 and 378.4 mV dec, respectively. -1 ( Figure 4 (b)), Ni NPS&SA -NC-L electrocatalytic HER kinetics show a lower Tafel slope than Ni. SA The Tafel slope of -NC-L indicates that Ni NPS and Ni SA The synergistic effect accelerated the initial water dissociation process (Volmer step).

[0054] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a Ni nanoparticle and Ni single-atom synergistic catalyst, characterized in that, Includes the following steps: Soluble zinc salt, soluble nickel salt and organic ligand are mixed in water, and then mixed with a solution containing polydopamine. The mixture is then subjected to light-protected aging, drying and pyrolysis in sequence to obtain the Ni particle and Ni single atom synergistic catalyst.

2. The preparation method of the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The molar ratio of Zn to the organic ligand in the soluble zinc salt is 1:

16.

3. The method for preparing the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The molar ratio of Zn in the soluble zinc salt to Ni in the soluble nickel salt is 3.2~12.8:

1.

4. The method for preparing the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The solvent in the polydopamine-containing solution is an equal volume mixture of anhydrous ethanol and water.

5. The method for preparing the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The polydopamine-containing solution also contains ammonia.

6. The method for preparing the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The light-protected aging process is carried out at a temperature of 30-50°C for 20-28 hours.

7. The method for preparing the Ni nanoparticle and Ni single-atom synergistic catalyst according to claim 1, characterized in that, The pyrolysis is carried out under an inert atmosphere, with a pyrolysis temperature of 850~1000℃, a holding time of 1~3h, and a heating rate of 5~6℃ / min.

8. A Ni nanoparticle and Ni single atom synergistic catalyst prepared by the method of preparing Ni nanoparticle and Ni single atom synergistic catalyst according to any one of claims 1 to 7.

9. The application of the Ni nanoparticles and Ni single-atom synergistic catalyst as described in claim 8 in the catalytic electrochemical reduction reaction of CO2.

10. The application of the Ni nanoparticles and Ni single-atom synergistic catalyst described in claim 8 in the preparation of Zn-CO2 batteries.

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