Ni-cu diatomic cluster electrocatalyst, preparation method and application thereof
By employing a sol-gel pyrolysis strategy and synergistic coordination and anchoring of S and N atoms, a Ni-Cu bimetallic cluster electrocatalyst was prepared. This solved the problems of size inhomogeneity, easy agglomeration, and poor stability of existing catalysts, achieving efficient and stable CO2 reduction to CO, making it suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUILIN UNIV OF ELECTRONIC TECH
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-05
AI Technical Summary
Existing Ni and Cu-based bimetallic cluster catalysts suffer from several drawbacks, including difficulty in precisely controlling cluster size, easy aggregation, insufficient exposure of active sites, and decreased catalytic efficiency; poor stability due to lack of effective synergistic anchoring between clusters and carbon supports; and difficulty in precisely matching cluster dispersion with metal loading, resulting in poor CO2 reduction selectivity.
A sol-gel pyrolysis strategy is adopted to form a Ni-Cu bimetallic cluster electrocatalyst through the synergistic coordination and anchoring of S and N atoms. Combined with a secondary thermal carbonization process, the uniform dispersion and stable anchoring of sub-nanometer Ni-Cu bimetallic clusters are achieved. The preparation method is simple, the raw materials can be selected from a wide range, and it is suitable for industrial scale-up.
The catalyst achieves high specific surface area, abundant defect sites, and a three-dimensional porous structure, which improves the Faraday efficiency and stability of CO2 reduction to CO. Its performance is superior to that of single metal catalysts, making it suitable for industrial applications.
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Figure CN122147419A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to an atomically precise Ni-Cu bimetallic cluster electrocatalyst (NiCu-ACs / NC), its preparation method, and its application in electrocatalytic CO2 reduction. Background Technology
[0002] Electrochemical CO2 reduction reaction (eCO2RR) is a key technology for realizing the recycling of carbon resources. Among them, the selective reduction of CO2 to CO has become the core research direction of eCO2RR because the products are easy to separate and have a wide range of applications. However, efficient non-precious metal catalysts are the core bottleneck to promote its industrialization.
[0003] Metal cluster catalysts, as novel catalytic materials at the sub-nanometer scale, combine the high atomic utilization of single-atom catalysts with the synergistic effect of nanocatalysts. Their small size (<1 nm) and atomically uniform dispersion structure can form abundant active sites, precisely control the behavior of reaction intermediates, and significantly improve catalytic performance, making them a research hotspot for non-noble metal eCO2RR catalysts.
[0004] Ni and Cu-based bimetallic clusters have become a preferred alternative to precious metals due to their low raw material cost and excellent electronic coupling effect. However, existing Ni and Cu-based bimetallic clusters still have three major problems: First, the cluster size is difficult to control precisely, and they tend to agglomerate into large particles, resulting in insufficient exposure of active sites and a significant decrease in catalytic efficiency. Second, the clusters and carbon supports lack an effective synergistic anchoring mechanism, making it easy for active sites to be lost and resulting in poor catalyst stability. Third, the cluster dispersion and metal loading are difficult to match precisely, which destroys the bimetallic synergistic effect and leads to poor CO2 reduction selectivity.
[0005] To address the aforementioned problems, this invention focuses on Ni-Cu bimetallic cluster materials with small size and high dispersion characteristics, and provides a Ni-Cu bimetallic cluster electrocatalyst that achieves uniform cluster dispersion through the synergistic anchoring of S and N atoms, thus solving the problems of difficult control of cluster size, easy agglomeration, and poor stability in existing clusters. Summary of the Invention
[0006] This invention addresses the problems of high difficulty in preparation, poor dispersibility, and insufficient stability of existing bimetallic cluster catalysts by providing a Ni-Cu bimetallic cluster electrocatalyst and its preparation method. Through a sol-gel pyrolysis strategy, the precise construction and stable anchoring of sub-nanometer Ni-Cu bimetallic clusters are achieved.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] This invention provides a Ni-Cu bimetallic cluster electrocatalyst (NiCu-ACs / NC), characterized by using a nitrogen-doped porous carbon support as the matrix, with Ni-Cu bimetallic atoms anchored to the support surface through synergistic coordination of S and N atoms, forming an atomically precise catalytic structure system. The Ni atoms are atomically dispersed, while the Cu atoms form atomic clusters. The average size of the Ni-Cu bimetallic clusters is 0.3–0.7 nm, and the catalyst contains Cu-Ni, Cu-N, and Ni-N bonds. The mass fraction of Ni is 0.3–0.5 wt%, and the mass fraction of Cu is 0.2–0.4 wt%.
[0009] Preferably, the catalyst has a three-dimensional porous framework structure and a BET specific surface area of 800-1200 m². 2 ·g -1 The total pore volume is 0.8 ~ 1.4 cm. 3 ·g -1 It includes micropores, mesopores and macropores, with the micropore size mainly concentrated in 2 ~ 3 nm, which is beneficial for reactant / product transport and increases the degree of exposure of active sites.
[0010] Preferably, the D band in the Raman spectrum of the catalyst is located at 1340 ~ 1350 cm⁻¹. -1 The G-band is located at 1590~1600 cm. -1 I D / I G The ratio of 1.10 to 1.20 indicates that the carbon support has abundant defect sites, providing sufficient sites for the bimetallic cluster anchoring; the XRD pattern shows only the broad diffraction peaks corresponding to the (002) and (101) crystal planes of the carbon material, with no metal or metal oxide diffraction peaks, confirming that the bimetallic cluster is highly dispersed.
[0011] Preferably, the oxidation state of Cu in the catalyst is +1.5 to +1.7, and the oxidation state of Ni is +0.8 to +1.2; the coordination number of Cu-N bond of Cu atom is 3.5 to 4.0, and the coordination number of Cu-Ni / Cu bond is 0.8 to 1.2; the coordination number of Ni-N bond of Ni atom is 3.0 to 4.0, and the coordination number of Ni-Cu / Ni bond is 0.2 to 0.6. This unique coordination environment ensures catalytic activity and stability.
[0012] This invention also provides a method for preparing the above-mentioned Ni-Cu bimetallic cluster electrocatalyst, which employs a sol-gel pyrolysis strategy and includes the following steps:
[0013] Step 1, Preparation of the precursor solution: Dissolve 1.5-2.5 g of thiohydrazine in 35-45 mL of deionized water at 75-85 °C and stir magnetically until completely dissolved; add 1.0-1.5 g of MgCl2·6H2O, 1.0-1.3 g of KOH, 0.15-0.25 g of Ni(CH3COO)2·4H2O and 0.12-0.20 g of Cu(CH3COO)2·H2O sequentially, and maintain the reaction at a constant temperature for 25-35 min; add 0.4-0.6 g of agarose and stir vigorously for 1.5-2.5 h to form a homogeneous and stable suspension;
[0014] Step 2, pretreatment: The suspension obtained in Step 1 is removed from the constant temperature water bath and allowed to cool naturally to room temperature, then aged for 8-12 hours to complete the gelation process. The aged gel is then freeze-dried at -55 to -45 °C, under a vacuum of 8-12 Pa, for 20-28 hours to remove moisture from the system, yielding a dry gel precursor containing Mg(OH)₂ and KCl precipitates. Freeze-drying avoids gel shrinkage and effectively maintains the porous structure of the precursor.
[0015] Step 3: First pyrolysis and washing. Place the dried gel precursor in a tube furnace and perform a first pyrolysis under an inert atmosphere (nitrogen or argon) with a purity ≥ 99.9%. The pyrolysis program is: 2 ~ 4 ℃·min -1 The temperature is increased to 300-400 °C at a heating rate and held for 0.5-1.5 h to achieve preliminary carbonization of the organic components; then the temperature is increased by 4-6 °C / min. -1 The temperature was increased to 900-1000 °C at a heating rate and held for 1.5-2.5 h to achieve coordination anchoring of the metal and nitrogen doping of the carbon support. After pyrolysis, the furnace was allowed to cool naturally to room temperature, and the pyrolysis products were collected. The pyrolysis products were placed in a 2-4 M nitric acid solution and stirred and washed at room temperature for 8-12 h to remove inorganic impurities such as Mg(OH)2 and KCl. Subsequently, the system was repeatedly washed with deionized water until the pH of the washing solution was 6.5-7.5. After filtration, the solid product was dried at 55-65 °C for 10-14 h to obtain the intermediate product.
[0016] Step 4, secondary pyrolysis: The intermediate product obtained in step 3 is placed in a tube furnace again and pyrolyzed at 900 ~ 1000 ℃ for 1.5 ~ 2.5 h under an inert atmosphere (nitrogen or argon) with a purity ≥ 99.9% for 1.5 ~ 2.5 h to further improve the graphitization degree of the carbon support and enhance the bonding strength between the bimetallic cluster and the carbon support. After pyrolysis, the furnace is cooled to room temperature and the product is collected to obtain the NiCu-ACs / NC catalyst.
[0017] In addition, when preparing Ni single-metal atom catalysts, only the corresponding Ni source is added in step 1, and no Cu source is added; when preparing Cu single-metal atom catalysts, only the corresponding Cu source is added in step 1, and no Ni source is added, while the other steps remain unchanged.
[0018] The Ni-Cu bimetallic cluster electrocatalyst provided by this invention is used for the electrocatalytic reduction of CO2, catalyzing the conversion of CO2 to CO. The reaction system is an H-type battery and a three-electrode system. The working electrode is carbon paper coated with the catalyst, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode. The electrolyte is a 0.1 M KHCO3 solution (pH = 6.5 ~ 7.0). CO2 gas is introduced for 20 ~ 40 min until saturation before the reaction. The reaction potential range is -0.5 V ~ -1.2 V (vs. RHE).
[0019] The beneficial effects of this invention are:
[0020] 1. By adopting a sol-gel pyrolysis strategy, through the synergistic coordination of S and N atoms of sulfur-containing ligands with Ni and Cu metals, combined with a secondary thermal carbonization process, the uniform dispersion and stable anchoring of sub-nanometer Ni-Cu bimetallic clusters are achieved, solving the problems of easy agglomeration and uneven size of traditional bimetallic clusters;
[0021] 2. The catalyst has a high specific surface area, abundant defect sites and a three-dimensional porous structure, which promotes the exposure of active sites and mass transport. Its CO Faraday efficiency is ≥ 92%, and it has excellent stability after 40 h of continuous electrolysis. Its performance is better than that of single metal atom catalysts.
[0022] 3. The preparation method is simple, the raw materials can be selected from a wide range, no complicated equipment is required, the reaction conditions are mild, and the bimetallic clusters and monometallic catalysts can be prepared in a controllable manner by adjusting the amount of metal salt, which is suitable for industrial scale-up. Attached Figure Description
[0023] Figure 1 TEM morphology and EDS elemental distribution of the NiCu-ACs / NC catalyst prepared in Example 1;
[0024] Figure 2 This is a schematic diagram of the bimetallic cluster charge distribution of the NiCu-ACs / NC catalyst prepared in Example 1;
[0025] Figure 3 Cu K-edge XAFS characterization of the NiCu-ACs / NC catalyst prepared in Example 1;
[0026] Figure 4 The image shows the Ni K-edge XAFS characterization of the NiCu-ACs / NC catalyst prepared in Example 1.
[0027] Figure 5 The XRD patterns of the NiCu-ACs / NC, 4Ni4Cu-ACs / NC, Cu-SAs / NC and Ni-SAs / NC catalysts prepared in Example 1 are shown.
[0028] Figure 6 Raman spectra of the NiCu-ACs / NC, 4Ni4Cu-ACs / NC, Cu-SAs / NC and Ni-SAs / NC catalysts prepared in Example 1;
[0029] Figure 7 The N2 adsorption-desorption isotherm of the NiCu-ACs / NC catalyst prepared in Example 1;
[0030] Figure 8 The pore size distribution diagram is shown for the NiCu-ACs / NC catalyst prepared in Example 1.
[0031] Figure 9 The high-resolution XPS spectrum of Ni 2p of the NiCu-ACs / NC catalyst prepared in Example 1;
[0032] Figure 10 The high-resolution XPS spectrum of Cu 2p of the NiCu-ACs / NC catalyst prepared in Example 1;
[0033] Figure 11 The N 1s high-resolution XPS spectrum of the NiCu-ACs / NC catalyst prepared in Example 1;
[0034] Figure 12 FE of the NiCu-ACs / NC, 4Ni4Cu-ACs / NC, Cu-SAs / NC and Ni-SAs / NC catalysts prepared in Example 1 CO Potential curve;
[0035] Figure 13 The CO partial current density-potential curves of the NiCu-ACs / NC, 4Ni4Cu-ACs / NC, Cu-SAs / NC and Ni-SAs / NC catalysts prepared in Example 1 are shown.
[0036] Figure 14Tafel slope diagrams of the NiCu-ACs / NC, 4Ni4Cu-ACs / NC, Cu-SAs / NC and Ni-SAs / NC catalysts prepared in Example 1;
[0037] Figure 15 The image shows the long-term stability test results of the NiCu-ACs / NC catalyst prepared in Example 1 at a potential of -0.9 V (vs. Ag / AgCl). Detailed Implementation
[0038] The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention.
[0039] Example 1
[0040] Step 1, Preparation of the precursor solution: Dissolve 2 g of thiohydrazine (purity ≥ 98%) in 40 mL of deionized water at 80 ℃ and stir magnetically until completely dissolved; then add 1.34 g of MgCl2·6H2O (purity ≥ 99%), 1.18 g of KOH (purity ≥ 99%), 0.2 g of Ni(CH3COO)2·4H2O (purity ≥ 99.5%), and 0.16 g of Cu(CH3COO)2·H2O (purity ≥ 99.5%) sequentially, and maintain a constant temperature of 80 ℃ for 30 min; add 0.53 g of agarose (purity ≥ 98%), and stir vigorously for 2 h to form a homogeneous and stable suspension;
[0041] Step 2, pretreatment: The suspension obtained in Step 1 is taken out of the constant temperature water bath and allowed to cool naturally to room temperature. Then it is allowed to stand and age for 10 h to complete the gelation. The aged gel is placed in a freeze dryer and dried at -50 ℃ and 10 Pa for 24 h to obtain a dry aerogel precursor containing Mg(OH)2 and KCl precipitates.
[0042] Step 3, initial pyrolysis and washing: The dried gel precursor is placed in a tube furnace and subjected to initial pyrolysis under a high-purity nitrogen atmosphere (purity ≥99.9%). The pyrolysis program is as follows: 3 °C / min. -1 The temperature was increased to 350 °C at a heating rate, held for 1 h, and then increased at a rate of 5 °C·min. -1 The temperature was increased to 950 °C at a rising rate and held for 2 h. After pyrolysis, the furnace was allowed to cool naturally to room temperature, and the pyrolysis products were collected. The pyrolysis products were placed in a 3 M nitric acid solution and washed with stirring at room temperature for 10 h to remove inorganic impurities such as Mg(OH)2 and KCl. Subsequently, the system was repeatedly washed with deionized water until the pH of the washing solution was neutral. After filtration, the solid product was dried at 60 °C for 12 h to obtain the intermediate product.
[0043] Step 4, secondary pyrolysis: The intermediate product obtained in step 3 is placed back into a tube furnace and pyrolyzed at 3 °C / min under a nitrogen atmosphere. -1 The temperature was increased to 950 °C at a heating rate and pyrolyzed at a constant temperature for 2 h. After pyrolysis, the furnace was cooled to room temperature, and the product was collected to obtain the NiCu-ACs / NC catalyst.
[0044] Example 2
[0045] Step 1, Preparation of the precursor solution: 1.5 g of thiohydrazine was dissolved in 35 mL of deionized water at 75 ℃ and magnetically stirred until completely dissolved; then 1.0 g of MgCl2·6H2O, 1.0 g of KOH, 0.15 g of Ni(CH3COO)2·4H2O and 0.12 g of Cu(CH3COO)2·H2O were added sequentially, and the reaction was carried out at a constant temperature of 75 ℃ for 25 min; then 0.4 g of agarose was added, and the mixture was stirred vigorously for 1.5 h to form a homogeneous and stable suspension;
[0046] Step 2, pretreatment: The suspension obtained in Step 1 was naturally cooled to room temperature and aged for 8 h, and then freeze-dried at -55 ℃ and 8 Pa for 20 h to obtain the dried gel precursor.
[0047] Step 3: First pyrolysis and washing. The dried gel precursor is placed in a tube furnace and pyrolyzed under an argon atmosphere at 2 °C / min. -1 Heat to 300 °C and hold for 0.5 h, then increase the temperature by 4 °C / min. -1 The temperature was raised to 900 °C and held for 1.5 h; after cooling, the product was washed with 2 M nitric acid for 8 h, rinsed with deionized water until pH = 6.5, filtered, and dried at 55 °C for 10 h to obtain the intermediate product.
[0048] Step 4, secondary pyrolysis: The intermediate product is pyrolyzed for 1.5 h in an argon atmosphere at 900 °C, and after cooling, NiCu-ACs / NC catalyst is obtained.
[0049] Example 3
[0050] Step 1, Preparation of the precursor solution: 2.5 g of thiohydrazine was dissolved in 45 mL of deionized water at 85 ℃ and magnetically stirred until completely dissolved; then 1.5 g of MgCl2·6H2O, 1.3 g of KOH, 0.25 g of Ni(CH3COO)2·4H2O and 0.20 g of Cu(CH3COO)2·H2O were added sequentially, and the reaction was carried out at a constant temperature of 85 ℃ for 35 min; then 0.6 g of agarose was added, and the mixture was stirred vigorously for 2.5 h to form a homogeneous and stable suspension;
[0051] Step 2, pretreatment: The suspension obtained in Step 1 was naturally cooled to room temperature and aged for 12 h, and then freeze-dried at -45 ℃ and 12 Pa for 28 h to obtain the dried gel precursor.
[0052] Step 3: Pyrolysis and washing. The dried gel precursor is placed in a tube furnace and pyrolyzed under a nitrogen atmosphere at 4 °C·min. -1 Heat to 400 °C and hold for 1.5 h, then reduce temperature by 6 °C / min. -1 The temperature was raised to 1000 °C and held for 2.5 h; after cooling, it was washed with 4 M nitric acid for 12 h, rinsed with deionized water until pH = 7.5, filtered, and dried at 65 °C for 14 h to obtain the intermediate product.
[0053] Step 4: Secondary pyrolysis. The intermediate product is pyrolyzed again at 1000 °C for 2.5 h under a nitrogen atmosphere. After cooling, the NiCu-ACs / NC catalyst is obtained.
[0054] Comparative Example 1
[0055] A Ni-Cu bimetallic catalyst with high metal loading is provided. The steps are basically the same as those in Example 1, except that the amount of Ni source and Cu source in step 1 is increased to 4 times that in Example 1.
[0056] Performance test results are as follows Figure 12 As shown, the CO Faradaic efficiency of this catalyst at a potential of -0.9 V (vs. Ag / AgCl) is significantly lower than that of Ni, Cu-ACs / NC in Example 1. TEM characterization shows that the average size of the metal clusters increases and local agglomeration occurs, confirming that excessive metal loading will destroy the bimetallic synergistic effect.
[0057] Comparative Example 2
[0058] A Ni-Cu bimetallic catalyst without S coordination is provided. The steps are basically the same as those in Example 1, except that no sulfur-containing ligands are added in step 1, and only a gelling agent is used as an organic ligand.
[0059] XPS test results showed that the intensity of the metal-N peak in the N 1s spectrum of this catalyst was weakened, and EXAFS fitting showed that the coordination numbers of Cu-N and Ni-N were significantly reduced. Catalytic performance test showed that its CO Faraday efficiency was lower than that of NiCu-ACs / NC in Example 1. The Faraday efficiency decreased significantly after continuous electrolysis for 20 h, confirming that the synergistic coordination of S and N atoms can enhance the binding strength between the bimetallic cluster and the carbon support and improve stability.
[0060] Structural characterization of NiCu-ACs / NC catalysts:
[0061] 1. TEM and EDS characterization, test results are as follows: Figure 1 As shown, the catalyst exhibits a three-dimensional porous framework structure, with Ni-Cu bimetallic clusters uniformly dispersed on the surface of nitrogen-doped carbon support. The average size is sub-nanometer, and there is no obvious agglomeration. The EDS elemental distribution map shows that C, N, S, Ni, and Cu elements are uniformly distributed, with no local enrichment of Ni and Cu, confirming the excellent dispersion of the bimetallic clusters.
[0062] 2. XAFS characterization, test results are as follows Figure 3 , Figure 4 As shown, the FT-EXAFS spectra of Cu K-edge and Ni K-edge show a Cu-Ni bond characteristic peak at approximately 2.2 Å, confirming the presence of Cu-Ni bonds in the catalyst. The simultaneous appearance of Ni-N and Cu-N bond characteristic peaks indicates that the bimetallic cluster is anchored to the carbon support through the coordinated coordination of S and N atoms, and that Cu-Ni, Cu-N, and Ni-N bonds are present, consistent with the structural features of claim 1.
[0063] 3. XRD characterization, test results are as follows Figure 5 As shown, NiCu-ACs / NC exhibits broad peaks of C(002) and (101) crystal planes only at 26° ~ 27° and 44° ~ 45°, with no metal or metal oxide diffraction peaks, indicating that the metal species are highly dispersed and there are no metal or metal oxide diffraction peaks, consistent with claim 3.
[0064] 4. Raman characterization, test results as follows Figure 6 As shown, the catalyst is at 1340 ~ 1350 cm⁻¹ -1 (D-band) and 1590 ~ 1600 cm -1 Characteristic peaks appear in (G band), I D / I G The ratio of 1.1 to 1.2 indicates that the carbon support has abundant defect sites, providing sufficient sites for bimetallic cluster anchoring.
[0065] 5. BET characterization, test results are as follows Figure 7 , Figure 8 As shown, the BET specific surface area of the catalyst is 900~1200 m². 2 ·g -1 The total pore volume is 1.0 ~ 1.3 cm. 3 ·g -1 The micropore size is mainly concentrated in 2.5 ~ 3.0 nm, and the BET specific surface area, total pore volume and micropore size all meet the range requirements. It is a three-dimensional porous structure containing micropores, mesopores and macropores, which is completely consistent with claim 2.
[0066] 6. XPS characterization, test results are as follows Figure 9 , Figure 10 , Figure 11 As shown, the Ni 2p spectrum confirms that the oxidation state of Ni is +1.0 to +1.2, and the Cu 2p spectrum confirms that the oxidation state of Cu is +1.5 to +1.7. The N 1s spectrum can be decomposed into five species: pyridine-N, pyrrole-N, graphite-N, metal-N, and oxide-N. The presence of the metal-N peak proves that Ni, Cu, and N atoms form coordination bonds. Combined with the EXAFS fitting results, the coordination number of Cu-N bond of Cu atom is 3.5 to 4.0, the coordination number of Cu-Ni / Cu bond is 0.8 to 1.2, the coordination number of Ni-N bond of Ni atom is 3.5 to 4.0, and the coordination number of Ni-Cu / Ni bond is 0.3 to 0.5. The oxidation states of Cu and Ni and the coordination numbers of each chemical bond all meet the range requirements and are completely matched with the coordination characteristics of claim 4.
[0067] Electrocatalytic performance test:
[0068] Step 1: Preparation of the working electrode. NiCu-ACs / NC catalyst, conductive carbon black, and Nafion solution are mixed at a mass ratio of 8:1:1. An appropriate amount of anhydrous ethanol is added, and the mixture is ultrasonically dispersed for 20-40 min to form a uniform catalyst ink. The catalyst ink is then uniformly coated onto the surface of carbon paper at a coating amount of 1 mg·cm⁻¹. -2 After drying at 50 ~ 70 ℃, the working electrode is obtained.
[0069] Step 2: The reaction system is set up using an H-type electrolytic cell and a standard three-electrode system. The working electrode is carbon paper coated with catalyst, the counter electrode is a platinum sheet, and the reference electrode is an Ag / AgCl electrode. The electrolyte is a 0.1 M KHCO3 aqueous solution (pH = 6.5 ~ 7.0). Before the reaction, high-purity CO2 gas is continuously introduced into the electrolyte for 30 min to make the electrolyte reach CO2 saturation.
[0070] Step 3: Performance testing. The reaction potential was controlled within the range of -0.5 V to -1.2 V (vs. RHE). Constant potential electrolysis was performed at room temperature, and the reaction products were detected using online gas chromatography. Parallel tests were conducted using Ni single-metal atom catalyst, Cu single-metal atom catalyst, and a highly metal-supported Ni-Cu bimetallic catalyst as control samples.
[0071] Test results:
[0072] 1. Faraday efficiency, test results are as follows Figure 12 As shown, at a potential of -0.9 V (vs. Ag / AgCl), the Faradaic efficiency of NiCu-ACs / NC catalyzing the conversion of CO2 to CO is ≥ 92%, which is significantly higher than that of the comparative samples and consistent with the performance characteristics of claim 10.
[0073] 2. Partial current density, test results are as follows: Figure 13 As shown, at a potential of -1.2 V (vs. RHE), the CO portion current density of NiCu-ACs / NC is ≥ 20 mA·cm⁻¹. -2 The catalytic activity was higher than that of the control sample, demonstrating excellent catalytic activity.
[0074] 3. Catalytic kinetics, test results are as follows: Figure 14 As shown, the Tafel slope of NiCu-ACs / NC is ≤ 230 mV·dec -1 The concentration was lower than that of the control sample, indicating that its CO2 reduction reaction kinetics were superior.
[0075] 4. Stability, test results are as follows: Figure 15 As shown, after continuous electrolysis at a potential of -0.9 V (vs. Ag / AgCl) for 40 h, NiCu-ACs / NC can still maintain a high initial Faraday efficiency and initial current.
[0076] After stability testing, XRD, XPS and TEM characterization showed that the bimetallic clusters did not aggregate and the three-dimensional porous morphology of the catalyst remained stable, consistent with the stability characteristics of claim 10.
Claims
1. A Ni-Cu bimetallic cluster electrocatalyst, characterized in that, The catalyst is a NiCu-ACs / NC catalyst formed by the coordinated coordination of S and N atoms of Ni-Cu bimetallic clusters and anchoring them on a nitrogen-doped porous carbon support; the Ni atoms are in an atomically dispersed state, and the Cu atoms form atomic clusters. The average size of the Ni-Cu bimetallic clusters is 0.3 ~ 0.7 nm, and Cu-Ni, Cu-N, and Ni-N bonds exist in the catalyst; the mass fraction of Ni in the catalyst is 0.3 ~ 0.5 wt%, and the mass fraction of Cu is 0.2 ~ 0.4 wt%.
2. The Ni-Cu bimetallic cluster electrocatalyst according to claim 1, characterized in that, The catalyst has a three-dimensional porous framework structure and a BET specific surface area of 800~1200 m². 2 ·g -1 The total pore volume is 0.8 ~ 1.4 cm. 3 ·g -1 It includes micropores, mesopores and macropores, with the micropore size mainly concentrated in 2 ~ 3 nm (calculated by BJH method).
3. The Ni-Cu bimetallic cluster electrocatalyst according to claim 1, characterized in that, The Raman spectrum of the catalyst shows the D band located at 1340–1350 cm⁻¹. -1 The G-band is located at 1590 ~ 1600 cm. -1 I D / I G The ratio is 1.10 ~ 1.20; the XRD pattern shows only the broad diffraction peaks of the corresponding carbon material (002) and (101) crystal planes, and no metal or metal oxide diffraction peaks.
4. The Ni-Cu bimetallic cluster electrocatalyst according to claim 1, characterized in that, The catalyst has Cu oxidation state of +1.5 to +1.7 and Ni oxidation state of +0.8 to +1.2; Cu-N bond coordination number of Cu atom is 3.5 to 4.0 and Cu-Ni / Cu bond coordination number is 0.8 to 1.2; Ni-N bond coordination number of Ni atom is 3.0 to 4.0 and Ni-Cu / Ni bond coordination number is 0.2 to 0.
6.
5. A method for preparing the Ni-Cu bimetallic cluster electrocatalyst as described in any one of claims 1-4, characterized in that, The sol-gel pyrolysis strategy was employed, comprising the following steps: Step 1, preparation of the precursor solution: 1.5–2.5 g of thiomenhydrinate was dissolved in 35–45 mL of deionized water at 75–85 °C. Then, 1.0–1.5 g of MgCl₂·6H₂O, 1.0–1.3 g of KOH, 0.15–0.25 g of Ni(CH₃COO)₂·4H₂O, and 0.12–0.20 g of Cu(CH₃COO)₂·H₂O were added sequentially. After reacting at a constant temperature for 25–35 min, 0.4–0.6 g of agarose was added and the mixture was vigorously stirred for 1.5–2.5 h to form a homogeneous suspension. Step 2, pretreatment: The suspension obtained in Step 1 was naturally cooled to room temperature and then aged for 8–12 hours. h, freeze-dry to obtain a dry gel containing Mg(OH)2 and KCl precipitates; Step 3, pyrolysis and washing: the dry gel is subjected to pyrolysis under an inert atmosphere, first at 2 ~ 4 ℃·min -1 The temperature was increased to 300-400℃ at a heating rate and held for 0.5-1.5 h, then increased at 4-6℃·min. -1 The temperature was increased to 900-1000 °C and held for 1.5-2.5 h. After cooling, the product was washed with 2-4 M nitric acid for 8-12 h, then rinsed with deionized water until neutral. The product was filtered and dried to obtain the intermediate product. In step 4, the intermediate product was pyrolyzed again at 900-1000 °C under an inert atmosphere for 1.5-2.5 h to obtain the NiCu-ACs / NC catalyst.
6. The preparation method according to claim 5, characterized in that: The ligand is selected from at least one of thiosemihydrazine and aminothiourea; the Ni source is selected from at least one of nickel acetoxyacetate tetrahydrate, nickel acetate, and nickel nitrate; the Cu source is selected from at least one of copper acetoxyacetate monohydrate, copper acetate, and copper nitrate; the magnesium salt in the template agent is magnesium chloride hexahydrate, and the inorganic base is selected from at least one of potassium hydroxide and sodium hydroxide; the gelling agent is selected from at least one of agarose and chitosan; the mass ratio of the ligand, Ni source, Cu source, magnesium salt, inorganic base, and gelling agent is (1 ~ 3): (0.15 ~ 0.8): (0.12 ~ 0.64): (1.0 ~ 1.5): (1.0 ~ 1.3): (0.4 ~ 0.7).
7. The preparation method according to claim 5, characterized in that, The inert atmosphere is nitrogen or argon, with a gas purity ≥ 99.9%; in step 2, the freeze-drying temperature is -55 ~ -45 ℃, the vacuum degree is 8 ~ 12 Pa, and the drying time is 20 ~ 28 h; in step 3, the drying temperature is 55 ~ 65 ℃, and the drying time is 10 ~ 14 h.
8. The preparation method according to claim 5, characterized in that: The pickling is performed using 2-4 M nitric acid or sulfuric acid as the pickling agent, at a temperature of room temperature to 80°C, for a time of 8-12 hours; the freeze-drying is performed at a temperature of -60 to -50°C for a time of 18-24 hours; and the drying is performed under vacuum at a temperature of 50-70°C for a time of 10-14 hours.
9. The application of the Ni-Cu bimetallic cluster electrocatalyst according to any one of claims 1-4, characterized in that, The catalyst is used for the electrocatalytic reduction of CO2, catalyzing the conversion of CO2 into CO; the reaction adopts an H-type battery and a three-electrode system, the electrolyte is a 0.1 M KHCO3 solution with pH = 6.5 ~ 7.0, saturated with CO2, and the reaction potential range is -0.5 V ~ -1.2 V (vs. RHE).
10. The application according to claim 9, characterized in that, At a potential of -0.9 V (vs. Ag / AgCl), the catalyst exhibits a CO Faradaic efficiency ≥ 92%; after 40 h of continuous electrolysis, it maintains a high initial Faradaic efficiency and current, with no bimetallic cluster aggregation; at a potential of -1.2 V (vs. RHE), the CO partial current density is ≥ 20 mA·cm⁻¹. -2 Tafel slope ≤ 230 mV·dec -1 .