The invention relates to a method based on 4, 4apos; zr-doped nickel-based electrocatalyst of-bipyridine chelating ligand as well as preparation method and application of Zr-doped nickel-based electrocatalyst

Abstract

The invention discloses a Zr-doped nickel-based electrocatalyst based on a 4, 4 '-dipyridyl chelating ligand and a preparation method and application thereof.The Zr-doped nickel-based electrocatalyst is characterized in that Ni < 2 + > serves as a central metal ion, 4, 4'-dipyridyl serves as the chelating ligand, and a stable coordination structure is constructed; zr is introduced as a doping element, and the electron density and the coordination environment of the catalyst are regulated and controlled by adjusting the doping proportion of Zr; and carbon fiber paper is used as a load electrode. A supported catalyst is prepared by using a constant-current electrodeposition method under a three-electrode system, and the catalyst is directly deposited on the surface of carbon fiber paper to form a self-supporting structure. The preparation method is simple in process, can be amplified on a large scale, and does not need a high-temperature roasting or complex solvent heat treatment step. The obtained catalyst is used for preparing adipic acid by electrocatalytic oxidation of cyclohexanol under an alkaline condition, and shows excellent catalytic activity and selectivity. The invention provides a green, efficient and low-cost adipic acid electrocatalytic synthesized novel electrocatalytic material, and the novel electrocatalytic material has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to a Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelating ligand, its preparation method and application, particularly to a nickel-based composite catalyst whose electronic structure is synergistically regulated by Zr doping and 4,4'-bipyridine chelating ligand, and further relating to its application in the electrocatalytic oxidation of cyclohexanol to adipic acid under alkaline conditions. Background Technology

[0002] Adipic acid is a key aliphatic dicarboxylic acid in current industrial production. It is a major monomer for synthetic fibers (nylon 66) and a major raw material for nylon engineering plastics. It is also widely used in the preparation of polyurethane, polyester, synthetic resins, synthetic leather, food additives, plasticizers, lubricants, pesticides, dyes and other fields.

[0003] Currently, the industrial production of adipic acid mainly involves the oxygen-deficient oxidation of cyclohexane to produce KA oil (a mixture of cyclohexanol and cyclohexanone). This KA oil is then catalytically oxidized to adipic acid in 40-60% concentrated nitric acid and with copper and vanadium catalysts, achieving a yield of approximately 80%. This process requires concentrated nitric acid, operates under harsh conditions, and causes severe corrosion and pollution to equipment. Furthermore, while NO and NO2 can be completely recovered and returned to the production process as nitric acid, the unrecovered N2O causes serious environmental pollution and requires downstream treatment, increasing capital expenditure. Therefore, there is a need to develop greener and more atomically efficient methods to replace traditional adipic acid production processes. One of the most likely strategies is to find cleaner oxidants to replace concentrated nitric acid. With the assistance of iron-based catalysts, H2O2 can be used to oxidize cyclohexene to synthesize adipic acid, but this requires a large amount of the strong oxidant H2O2, which inevitably increases the production cost.

[0004] Compared with thermocatalytic routes, electrocatalytic synthesis offers milder conditions, smaller scale, and greater efficiency, and electrolysis can be effectively controlled by adjusting current and voltage. Furthermore, electrocatalytic oxidation replaces the kineticly slow oxygen evolution reaction (OER), providing a promising coupled hydrogen production strategy for achieving the co-production of pure hydrogen and high-value-added products, as well as improving energy efficiency. BVLyalin and VA Petrosya (Russion Chemical Bulletin, 2004, 53(3), 688-692) reported the use of NiOOH anolyte electrolysis of cyclohexanol or cyclohexanone under alkaline conditions to generate adipic acid salt, followed by adjusting the salt to acidic conditions to prepare adipic acid, but the yield was very low. Methods disclosed in Chinese patent literature such as "Electrochemical Preparation Process of Adipic Acid" (application publication number CN 101092705 A) indirectly oxidize cyclohexene to generate adipic acid, but the low current efficiency and adipic acid yield still fail to meet requirements. A recently published Chinese patent document, "A Method for Preparing Adipic Acid by Electrochemical Oxidation of Cyclohexanone" (Application Publication No. CN 113337836 A), describes a method to increase the yield of adipic acid by introducing plasma gas into the electro-oxidation system of cyclohexanone. However, the catalyst preparation, electrolyte composition, and gas-conducting electrolysis process are all quite complex, which will significantly increase production costs. In recent years, metal complexes or chelated ligand catalysts have attracted attention due to their tunable electronic structures and unique coordination environments. However, current research largely focuses on traditional ligand structures, lacking systematic work utilizing the electronic effects of substituents to achieve fine-tuning. Furthermore, these ligand catalysts often suffer from insufficient stability and are prone to dissociation and deactivation with long-term use. Summary of the Invention

[0005] Technical problems addressed: To address the problems of low catalyst activity (nickel-based catalysts exhibit low catalytic activity in the electro-oxidation of cyclohexanol), poor selectivity (difficulty in effectively controlling the conversion of intermediate products to the target product (adipic acid), resulting in numerous side reactions), and complex preparation processes (existing catalyst preparation steps are cumbersome and not conducive to industrial application) in existing technologies, this invention proposes a Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelating ligands, along with its preparation method and application. By proposing a nickel-based composite catalyst based on substituted bipyridine chelating ligands and introducing Zr to achieve synergistic regulation of coordination and electronic structure, its catalytic performance in the electro-oxidation of cyclohexanol is significantly improved.

[0006] Technical solution: The first objective of this invention is to provide a method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelating ligand, the steps of which are as follows:

[0007] Step 1: Use a water-DMF mixed solution containing nickel nitrate (Ni(NO3)2), 4,4-bipyridine and ZrCl4 as the electrolyte. The concentration of nickel nitrate is 0.05M-0.15M, the concentration of 4,4-bipyridine is 0.05M-0.15M, the atomic percentage of Zr in ZrCl4 relative to Ni in Ni(NO3)2 is 1-10%, and the volume ratio of water to DMF is 1-2:1.

[0008] Step 2: Immerse the working electrode, counter electrode, and reference electrode in the electrolyte, and maintain a constant cathode current density of 10-50 mA·cm⁻¹. -2 Electrodeposition reaction is carried out under these conditions for 100-300 s.

[0009] Step 3: After electrodeposition, the working electrode is rinsed several times with ethanol and ultrapure deionized water, and then vacuum dried at room temperature to obtain the supported Ni-Zr-4,4-BD catalyst.

[0010] This invention uses nickel as the central metal ion and 4,4'-bipyridine (4,4-BD) as the chelating ligand to construct a stable coordination structure. Zr is introduced as a dopant element, and the electron density and coordination environment of the catalyst are controlled by adjusting its doping ratio (1%~10%). Carbon fiber paper (CFP) is used as the supported electrode. The supported catalyst is prepared using a galvanostatic electrodeposition method in a three-electrode system, directly depositing the catalyst onto the CFP surface to form a self-supporting structure.

[0011] Preferably, in step one, the atomic percentage of Zr in ZrCl4 relative to Ni in Ni(NO3)2 is 5%.

[0012] Preferably, the working electrode in step two is carbon fiber paper.

[0013] Preferably, the carbon fiber paper has a size of 1×2 cm. 2 .

[0014] Preferably, the counter electrode is a graphite rod that has been cleaned with acetone and ethanol.

[0015] Preferably, the reference electrode is an Ag / AgCl electrode.

[0016] The second objective of this invention is to provide a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand prepared by the above-described method.

[0017] The third objective of this invention is the application of the aforementioned Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelate ligand in the electrocatalytic oxidation of cyclohexanol to adipic acid under alkaline conditions, wherein the alkaline conditions are 0.1-1M NaOH.

[0018] Preferably, the electrocatalytic oxidation is carried out using a standard H-type electrolytic cell in a three-cell system: a Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelate ligand is used as the working electrode, a Pt sheet is used as the counter electrode, and Ag / AgCl is used as the reference electrode; the electrolyte is a mixed solution of NaOH and cyclohexanol; the electrocatalytic oxidation reaction is carried out at room temperature with a potential range of 1.52~1.62 V vs. RHE.

[0019] Preferably, the concentration of NaOH in the electrolyte is 1 M and the concentration of cyclohexanol is 0.1 M.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages and positive effects:

[0021] 1. Significantly improved catalytic activity and selectivity: At the same potential, the current density of the 5 at.% Zr-doped sample was significantly higher than that of the control sample, and the selectivity of the target product adipic acid was significantly improved.

[0022] 2. Simple preparation process and easy to scale up: The catalyst can be loaded onto carbon fiber paper in situ using a one-step electrodeposition method, without the need for subsequent high-temperature calcination or complex solvothermal treatment.

[0023] 3. Process parameters (such as current density, deposition time, and electrolyte composition) are easy to control, which is conducive to the controllable synthesis and industrialization of fine chemicals.

[0024] 4. Green, environmentally friendly, energy-saving and efficient: It does not use concentrated nitric acid or strong oxidant H2O2, thus avoiding the emission of toxic gases; the reaction is carried out at normal temperature and pressure, reducing energy consumption.

[0025] In summary, this invention provides a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelating ligand for the efficient electrocatalytic oxidation of cyclohexanol to adipic acid under alkaline conditions. It exhibits excellent catalytic activity and selectivity in a 1 M NaOH + 0.1 M cyclohexanol electrolyte, with the 5 at.% Zr-doped sample showing the best performance. Linear sweep voltammetry (LSV) testing shows that its oxidation current is significantly higher than that of the undoped sample. 1¹H NMR analysis showed a significant improvement in the selectivity of the target product, adipic acid. This technology eliminates the need for harmful reagents such as concentrated nitric acid or H₂O₂, offering mild reaction conditions, low energy consumption, and high selectivity, demonstrating significant advantages in environmental friendliness. The catalyst is prepared using a one-step electrodeposition method, a simple process that is easy to scale up and suitable for industrial production. Adipic acid, a key raw material for nylon 66 and various polymer materials, has a large market demand. Current production processes suffer from heavy pollution and high costs, necessitating green alternatives. This invention, by enhancing catalytic activity and product selectivity, is expected to significantly reduce production costs and improve energy efficiency through a hydrogen production coupling strategy. This technology has promising market application prospects and economic potential. Attached Figure Description

[0026] Figure 1 NiZr (5%) Transmission electron microscopy (TEM) images and corresponding elemental mapping diagrams of Ni-4,4-BD, Ni-4,4-BD, and Ni(OH)2. In the figures, (a) represents Ni(OH)2, (b) represents Ni-4,4-BD, and (c) represents NiZr. (5%) -4,4-BD;

[0027] Figure 2 NiZr (5%) XRD patterns of -4,4-BD, Ni-4,4-BD and Ni(OH)2;

[0028] Figure 3 NiZr (5%) XPS images of Ni-4,4-BD, Ni-4,4-BD and Ni(OH)2, where (a) is the Ni spectrum and (b) is the Zr spectrum;

[0029] Figure 4 NiZr (5%) Fourier transform infrared spectra of -4,4-BD, Ni-4,4-BD, Ni(OH)2 and 4,4-BD;

[0030] Figure 5 LSV diagrams of cyclohexanol electro-oxidation of catalysts in Examples 1-5 and Comparative Examples 1-2;

[0031] Figure 6 NiZr (5%) Selectivity of cyclohexanol electro-oxidation products of Ni-4,4-BD, Ni-4,4-BD and Ni(OH)2;

[0032] Figure 7 NiZr (5%) Cyclic stability plot of -4,4-BD;

[0033] Figure 8 NiZr(5%) -4,4-BD, Ni-4,4-BD, Ni(OH)2 and NiZr (5%) Graph of yield changes from 0 to 6 hours;

[0034] Figure 9 NiZr (x%) Yields and Faraday efficiencies of Zr doping concentrations (1%-10%) in -4,4-BD. Detailed Implementation

[0035] The following specific embodiments provide a more detailed description of the Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelate ligands provided by the present invention, as well as its preparation method and application.

[0036] Unless otherwise specified, the raw materials used in the embodiments of this invention are all from commercially available products.

[0037] Example 1 NiZr (1%) -4,4-BD electrode material

[0038] A water-DMF mixed solution containing nickel nitrate (Ni(NO3)2), 4,4'-bipyridine, and ZrCl4 was used as the electrolyte (total volume 30 mL). The concentrations of Ni(NO3)2 and 4,4'-bipyridine ligand (4,4-BD) were 0.1 M and 0.05 M respectively. The ZrCl4 contained Zr... 4+ The atomic percentage of Ni in Ni(NO3)2 is 1%, and the volume ratio of water to DMF is 3:2. The electrolyte is added to the electrolytic cell. Carbon fiber paper (CFP, size 1×2 cm) 2 A graphite rod cleaned with acetone and ethanol was used as the working electrode, and an Ag / AgCl electrode was used as the reference electrode. A constant cathode current density of 20 mA·cm⁻¹ was applied. -2 Electrodeposition was carried out under the following conditions for 240 seconds. After electrodeposition, the resulting electrode was rinsed several times with ethanol and ultrapure deionized water, and then vacuum dried at room temperature to obtain the supported Ni-Zr-4,4-BD catalyst electrode material, denoted as NiZr. (1%) -4,4-BD.

[0039] Example 2 NiZr (3%) -4,4-BD electrode material

[0040] Same as Example 1, except that only the Zr in the electrolyte is removed. 4+ The content of Ni was adjusted to 3 at.% (atomic percentage relative to Ni), and all other experimental steps (including electrolyte composition, electrode preparation, deposition parameters, and post-processing) remained consistent. The obtained electrode material was denoted as NiZr. (3%)-4,4-BD.

[0041] Example 3 NiZr (5%) -4,4-BD electrode material

[0042] Same as Example 1, except that only the Zr in the electrolyte is removed. 4+ The content of Ni was adjusted to 5 at.% (atomic percentage relative to Ni), and other experimental conditions remained unchanged. The resulting electrode material was denoted as NiZr. (5%) -4,4-BD.

[0043] Example 4 NiZr (7%) -4,4-BD electrode material

[0044] Same as Example 1, except that only the Zr in the electrolyte is removed. 4+ The content of Ni was adjusted to 7 at.% (atomic percentage relative to Ni), and other experimental conditions remained unchanged. The resulting electrode material was denoted as NiZr. (7%) -4,4-BD.

[0045] Example 5 NiZr (10%) -4,4-BD electrode material

[0046] Same as Example 1, except that only the Zr in the electrolyte is removed. 4+ The doping ratio was increased to 10 at.% (atomic percentage relative to Ni), and other experimental conditions remained unchanged. The resulting electrode material is denoted as NiZr. (10%) -4,4-BD.

[0047] Comparative Example 1: Ni-4,4-BD Electrode Material

[0048] Same as Example 1, except that no Zr is added to the electrolyte. 4+ Salt. The electrolyte contained only 0.1 M Ni(NO3)2 and 0.05 M 4,4'-bipyridine ligand, and the solvent remained a mixture of H2O and DMF in a volume ratio of 3:2. Other experimental conditions included electrode configuration and current density (20 mA·cm). -2 The deposition time (240 s) and post-processing method were the same as in Example 1, and the undoped Zr Ni-4,4-BD electrode material was finally obtained, denoted as Ni-4,4-BD.

[0049] Comparative Example 2: Ni(OH)2 Electrode Material

[0050] This comparative example provides a Ni-based electrode material without 4,4'-bipyridine ligand and undoped with Zr as a control sample. Specifically, the same three-electrode system and electrodeposition parameters (current density 20 mA·cm⁻¹) as in Example 1 were used.-2 The time was 240 s, but the electrolyte contained only 0.1 M Ni(NO3)2, without the addition of any organic ligands or Zr. 4+ Salt. Pure water was used as the solvent. After electrodeposition, the electrode surface was washed with deionized water to obtain the Ni(OH)2 electrode material, denoted as Ni(OH)2.

[0051] Performance testing:

[0052] I. Physicochemical property analysis of the catalysts prepared in Examples 1-5 and Comparative Examples 1-2:

[0053] NiZr prepared in Example 3 (5%) The microstructure of Ni-4,4-BD prepared in Comparative Example 1 and Ni(OH)2 prepared in Comparative Example 2 was characterized by transmission electron microscopy. The results are as follows: Figure 1 As shown, the Ni(OH)₂ in Comparative Example 2, which is uncoordinated with 4,4-BD and undoped with Zr, exhibits a two-dimensional plate-like morphology, while the Ni-4,4-BD prepared in Comparative Example 1 and the NiZr prepared in Example 3... (5%) -4,4-BD exhibits a rod-like microstructure. Elemental mapping diagrams confirm that NiZr... (5%) Successful doping and uniform distribution of element Zr in -4,4-BD.

[0054] The obtained NiZr (5%) -4,4-BD and control samples were characterized by XRD to obtain the following results: Figure 2 The XRD pattern shown is shown. The comparative example Ni(OH)2 phase is α-Ni(OH)2 (PDF#38-0715), while after coordination with 4,4-BD and doping with Zr, the phase transitions from α to β-Ni(OH)2 (PDF#14-0117).

[0055] For NiZr (5%) XPS characterization of -4,4-BD, Ni-4,4-BD, and Ni(OH)2 yielded the following results: Figure 3 As shown, the shift in the Ni peak may be due to the altered chemical environment of Ni caused by the coordination bonding of the ligand Ni-4,4-BD. The Zr peak further confirms the successful doping of Zr.

[0056] like Figure 4 The Fourier transform infrared spectrum of the comparative example Ni(OH)2 is shown at 3636 cm⁻¹. -1 The peak at that location is attributed to the vibration of its -OH group; in contrast, the peaks at Ni-4,4-BD and NiZr... (5%) The -OH vibration in -4,4-BD was significantly weakened, and a characteristic peak belonging to 4,4-BD appeared, indicating that it was successfully coordinated.

[0057] II. Performance testing and analysis of the catalysts prepared in Examples 1-5 and Comparative Examples 1-2 for the electro-oxidation of cyclohexanol to adipic acid:

[0058] First, a three-electrode system was constructed, using the catalytic electrodes prepared in Examples 1-5 and Comparative Examples 1-2 directly as the working electrode, a Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode. Then, an electrolyte consisting of 1 M NaOH and 0.1 M cyclohexanol was prepared. All experimental operations were performed at an isothermal temperature of 303 K. Using a CHI 660E electrochemical workstation, LSV (linear sweep voltammetry) tests were conducted on the materials in the above electrolyte at a scan rate of 0.5 mV s. -1 Furthermore, electrolysis experiments were conducted for 0.5–6 hours at a constant potential within the range of 1.57–1.62 V vs. RHE (without iR compensation), with a rotation speed of 1600 rpm. Samples were taken periodically during the process, and the results were analyzed using… 1 H NMR analysis of the product composition (mainly including adipic acid, glutaric acid and succinic acid, with adipic acid being the target product).

[0059] The LSV results of Examples 1-5 and Comparative Examples 1-2 are as follows: Figure 5 As shown (CFP in the figure is a pure carbon paper substrate), the cyclohexanol electro-oxidation current of Ni(OH)₂ is relatively low. After coordination with 4,4-BD, the oxidation current of Ni-4,4-BD increases. Further doping with Zr results in varying degrees of increase in oxidation current depending on the Zr ratio, and the NiZr prepared in Example 3... (5%) The oxidation current of -4,4-BD is the largest. The selectivity of the electrolysis products is analyzed, such as... Figure 6 As shown, compared with the comparative examples Ni(OH)2 and Ni-4,4-BD, Example 3 exhibits higher adipic acid selectivity.

[0060] For NiZr (5%) Cyclic stability tests were conducted using -4,4-BD. To verify the feasibility of this catalytic system in potential practical applications, we constructed a customized flow electrolyzer for simultaneous electro-oxidation of KA to AA and H2 precipitation. This system includes a flow plate, gaskets, a peristaltic pump, an anion exchange membrane, a DC regulated power supply, and electrodes (NiZr). (5%) -4,4-BD was used as the anode, NF as the cathode (working area 4 square centimeters), and a peristaltic pump was used to circulate 1.0 M sodium hydroxide and 0.1 M cyclohexanol as the anolyte. Results are shown in [link to results]. Figure 7 , Figure 7 The tested NiZr content is shown. (5%) -4,4-BD catalysts exhibit stability up to 100 h.

[0061] For NiZr (5%) -4,4-BD, Ni-4,4-BD, Ni(OH)2 and NiZr (5%) The yield changes of four different catalysts from 0 to 6 h were tested and statistically analyzed. Electrolysis was performed using a three-electrode system with 1.0 M sodium hydroxide and 0.1 M cyclohexanol as the anolyte. Electrolyte samples were collected at different electrolysis times for quantitative NMR analysis. Results are shown below. Figure 8 , Figure 8 The results showed that different catalyst samples generated products rapidly over time in the first three hours. After 3 hours, product generation slowed down and some catalysts even showed negative growth. This is because some products may be further converted into other products.

[0062] For NiZr (x%) The yields and Faraday efficiencies of Zr doping concentrations (1%-10%) in -4,4-BD catalysts were statistically analyzed using a three-electrode system with 1.0 M sodium hydroxide and 0.1 M cyclohexanol as the anolyte. Electrolysis products from catalysts with different Zr doping concentrations were collected and quantitatively analyzed using NMR spectroscopy. Results are detailed below. Figure 9 , Figure 9 Displaying NiZr (5%) -4,4-BD exhibited the highest yield (81.6%) and the highest Faraday efficiency (88.6%). Comparative analysis revealed that increasing the Zr content significantly improved the adipic acid production rate within a shorter timeframe; however, excessive Zr incorporation reduced the adipic acid yield, indicating that excessive Zr has a negative impact on adipic acid, possibly by masking the active sites of the reaction.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand, characterized in that, The steps are as follows: Step 1: Use a water-DMF mixed solution containing nickel nitrate, 4,4-bipyridine, and ZrCl4 as the electrolyte. The concentration of nickel nitrate is 0.05M-0.15M, the concentration of 4,4-bipyridine is 0.05M-0.15M, the atomic percentage of Zr in ZrCl4 relative to Ni in nickel nitrate is 1-10%, and the volume ratio of water to DMF is 1-2:

1. Step 2: Immerse the working electrode, counter electrode, and reference electrode in the electrolyte, and maintain a constant cathode current density of 10-50 mA·cm⁻¹. -2 Electrodeposition reaction is carried out under these conditions for 100-300 s. Step 3: After electrodeposition, the working electrode is rinsed several times with ethanol and ultrapure deionized water, and then vacuum dried at room temperature to obtain the supported Ni-Zr-4,4-BD catalyst.

2. The method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand according to claim 1, characterized in that, In step one, the atomic percentage of Zr in ZrCl4 relative to Ni in nickel nitrate is 5%.

3. The method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand according to claim 1, characterized in that, In step two, the working electrode is carbon fiber paper.

4. The method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelating ligand according to claim 3, characterized in that, The carbon fiber paper has a size of 1×2 cm. 2 .

5. The method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand according to claim 1, characterized in that, The counter electrode is a graphite rod that has been cleaned with acetone and ethanol.

6. The method for preparing a Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand according to claim 1, characterized in that, The reference electrode is an Ag / AgCl electrode.

7. A Zr-doped nickel-based electrocatalyst based on a 4,4'-bipyridine chelate ligand prepared according to the method described in any one of claims 1-6.

8. The application of the Zr-doped nickel-based electrocatalyst based on the 4,4'-bipyridine chelate ligand as described in claim 7 in the electrocatalytic oxidation of cyclohexanol to adipic acid under alkaline conditions, characterized in that... The alkaline condition is 0.1-1M NaOH.

9. The application according to claim 8, characterized in that, The electrocatalytic oxidation was carried out using a standard H-type electrolytic cell in a three-cell system: a Zr-doped nickel-based electrocatalyst based on 4,4'-bipyridine chelate ligand was used as the working electrode, a Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode; the electrolyte was a mixed solution of NaOH and cyclohexanol; the electrocatalytic oxidation reaction was carried out at room temperature with a potential range of 1.52~1.62 V vs. RHE.

10. The application according to claim 9, characterized in that, The concentration of NaOH in the electrolyte is 1 M, and the concentration of cyclohexanol is 0.1 M.

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