Nickel-doped hydroxyl cobalt oxide catalytic electrode as well as preparation method and application thereof

Abstract

The invention provides a nickel-doped hydroxyl cobalt oxide catalytic electrode as well as a preparation method and application thereof. The nickel-doped cobalt oxyhydroxide catalytic electrode comprises a foamed nickel substrate and nickel-doped cobalt oxyhydroxide uniformly loaded on the surface of the foamed nickel substrate, the molecular formula of the nickel-doped cobalt oxyhydroxide is Ni-CoOOH, and the nickel-doped cobalt oxyhydroxide is of a wrinkled nanosheet structure. The nickel-doped hydroxyl cobalt oxide catalytic electrode is prepared through a two-step method of room-temperature electro-deposition and electrochemical reconstruction, nickel doping is beneficial to regulation and control of the electronic structure of the material, more catalytic active sites can be exposed through the nanosheet morphology, and therefore the dynamic process of catalytic reaction is promoted. The catalytic electrode shows excellent catalytic activity and stability in the aspect of upgrading hydrolysate of polyethylene glycol terephthalate (PET) waste plastics into formate with high added value through electro-catalysis.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic materials, and in particular to a nickel-doped cobalt oxyhydroxide catalytic electrode, a preparation method thereof, and an application thereof. Background Art

[0002] In modern industry, plastic products have become indispensable basic materials due to their excellent physical and chemical properties. Polyethylene terephthalate (PET), a core polymer, has an annual global production of 82 million tons and is widely used in packaging, textiles, and other fields. However, over 80% of waste PET enters the environment through landfill or natural disposal. The microplastics and toxic monomers released during its degradation process have caused serious water pollution, necessitating the development of efficient and environmentally friendly recycling technologies.

[0003] The existing mainstream recycling technologies mainly include mechanical recycling and thermochemical treatment. However, the mechanical recycling method mainly achieves recycling through melt re-granulation, but after multiple cycles, the molecular chain breaks, resulting in a sharp decline in the mechanical properties of the recycled material; the thermochemical treatment method needs to be carried out under high temperature and high pressure conditions above 400°C, which has high energy consumption, catalyst deactivation, and the production of pollutants such as dioxins. Electrocatalytic PET conversion technology is considered to be the most ideal alternative because it can be carried out at room temperature and pressure. PET is first hydrolyzed into terephthalic acid and ethylene glycol in an alkaline medium, and ethylene glycol is converted into high-value-added chemicals such as formic acid and glycolic acid through electrochemical oxidation. However, the existing electrocatalytic PET conversion technology is limited by the complex reaction process, which leads to hysteresis in the reaction kinetics, and then its conversion efficiency is low at industrial-grade current density. When the current density is greater than 100mA cm -2 This will trigger a competitive reaction, resulting in a decrease in the selectivity of the target product and making it impossible to apply it on a large scale. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the deficiencies in the prior art, the present invention provides a nickel-doped cobalt oxyhydroxide catalytic electrode and a preparation method and application thereof, which solve the problems raised in the above background technology.

[0006] (2) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] According to a first aspect of the present invention, a nickel-doped cobalt oxyhydroxide catalytic electrode is provided, comprising a nickel foam substrate and nickel-doped cobalt oxyhydroxide uniformly loaded on the surface of the nickel foam substrate, wherein the nickel-doped cobalt oxyhydroxide has a molecular formula of Ni-CoOOH and has a wrinkled nanosheet structure.

[0009] Preferably, the main exposed surface of the nickel-doped cobalt oxyhydroxide is the (004) surface of CoOOH, and the size of the corrugated nanosheet structure is 500 nm to 2 μm.

[0010] Preferably, the nickel doping amount in the nickel-doped cobalt oxyhydroxide is 2.79%.

[0011] According to a second aspect of the present application, a preparation method of a nickel-doped cobalt oxyhydroxide catalytic electrode is provided, comprising the following steps:

[0012] (1) adding cobalt salt and nickel salt into water, stirring to obtain an electrolyte;

[0013] (2) taking a foamed nickel substrate as a working electrode, saturated silver / silver chloride as a reference electrode, and a platinum sheet or a graphite rod as a counter electrode, respectively placing the working electrode, the reference electrode and the counter electrode in the electrolyte prepared in step (1), and applying a constant current to the working electrode to obtain a preset electrode;

[0014] (3) taking the preset electrode prepared in step (2) as a working electrode, saturated silver / silver chloride as a reference electrode, and a platinum sheet or a graphite rod as a counter electrode, assembling a three-electrode system in a PET hydrolysis solution, and performing positive voltage cyclic voltammetry activation on the working electrode to obtain the catalytic electrode through electrochemical oxidation reconstruction.

[0015] Preferably, in step (1), the concentration of the cobalt salt in the electrolyte is 50-125 mM, and the cobalt salt is in terms of cobalt ions in moles;

[0016] the concentration of the nickel salt in the electrolyte is 25 mM, and the nickel salt is in terms of nickel ions in moles.

[0017] Preferably, in step (1), the cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride and cobalt sulfate;

[0018] the nickel salt is selected from at least one of nickel nitrate, nickel chloride and nickel sulfate.

[0019] Preferably, in step (2), the constant current density applied to the working electrode is -40 to -200 mA cm -2 the time for applying the constant current density to the working electrode is 200-600 s.

[0020] Preferably, in step (3), the voltage for performing positive voltage cyclic voltammetry activation on the working electrode is 0-2 V, and the time for performing positive voltage cyclic voltammetry activation on the working electrode is 10-30 min.

[0021] According to a third aspect of the present application, there is provided a use of the nickel-doped cobalt oxyhydroxide catalytic electrode or the catalytic electrode obtained according to the above preparation method in electrocatalytic regeneration of polyethylene terephthalate waste plastic to recover formate.

[0022] Advantages

[0023] The present application provides a nickel-doped cobalt oxyhydroxide catalytic electrode, a preparation method and a use thereof. The present application has the following advantages:

[0024] (1) The nickel-doped cobalt oxyhydroxide catalytic electrode provided by the present application has nickel-doped cobalt oxyhydroxide nanosheet arrays closely grown on the surface of a nickel foam. The nickel-doped cobalt oxyhydroxide nanosheet arrays can not only fully expose the surface of the material to contact with reaction species, but also enhance the interaction between the catalytic material and the nickel foam substrate, thereby promoting the rapid transfer of electrons. In addition, the prepared catalytic electrode has a three-dimensional self-supporting electrode structure and excellent structural stability, and can be applied to industrial electrocatalytic reactions and is easy to recycle and reuse.

[0025] (2) The preparation method of the nickel-doped cobalt oxyhydroxide catalytic electrode provided by the present application completes the preparation of the nickel-doped cobalt oxyhydroxide catalytic electrode at room temperature and normal pressure through an electrochemical deposition and electrochemical reconstruction method, which is energy-saving and simple.

[0026] (3) The nickel-doped cobalt oxyhydroxide catalytic electrode provided by the present application can drive a high current density of 500 mA cm -2 at a low voltage of 1.38 V in the electrocatalytic PET conversion process, and the faradic efficiency of formate production can reach 95% at a current density of 200 mA cm -2 , the yield of formate can reach 6.05 mmol h -2 cm - 1 cm -2 at a current density of 600 mA cm -2 , and the electrode can be operated for more than 50 h at a current density of 500 mA cm BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A synthesis process schematic diagram of the nickel-doped cobalt oxyhydroxide catalytic electrode provided by Example 1 of the present application is shown in the figure;

[0028] Figure 2 XRD patterns in the preparation process of the nickel-doped cobalt oxyhydroxide catalytic electrode provided by Example 1 of the present application are shown in the figure, wherein a figure is an XRD pattern of a nickel-doped cobalt hydroxide pre-electrode, and b figure is an XRD pattern of a nickel-doped cobalt oxyhydroxide catalytic electrode;

[0029] Figure 3SEM images in the preparation process of the nickel-doped cobalt oxyhydroxide catalytic electrode provided in Embodiment 1 of the present application, wherein a figure is an SEM image of the nickel-doped cobalt hydroxide preset electrode at 200 nm, b figure is an SEM image of the nickel-doped cobalt hydroxide preset electrode at 2 μm, c figure is an SEM image of the nickel-doped cobalt oxyhydroxide catalytic electrode at 200 nm, and d figure is an SEM image of the nickel-doped cobalt oxyhydroxide catalytic electrode at 2 μm;

[0030] Figure 4 Transmission electron microscope (TEM) image and high-resolution transmission electron microscope (HRTEM) image of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Embodiment 1 of the present application, wherein a figure is a TEM image at 100 nm, and b figure is a HRTEM image at 2 nm;

[0031] Figure 5 Element distribution map of high-resolution electron microscope imaging of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Embodiment 1 of the present application;

[0032] Figure 6 XPS image of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Embodiment 1 of the present application, wherein a figure is an XPS image of Co2p, and b figure is an XPS image of Ni 2p;

[0033] Figure 7 Ethylene glycol oxidation performance test of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Embodiment 1 of the present application, wherein a figure is an OER and EGOR linear voltammetry curve in PET hydrolysate, and b figure is formate salt faradic efficiency and yield of the catalytic electrode prepared in Embodiment 1 under different current density tests;

[0034] Figure 8 EGOR performance test of the catalytic electrode prepared in Embodiments 1-4 and Comparative Example 1 in PET hydrolysate, wherein a figure is an EGOR linear voltammetry curve of the catalytic electrode prepared in Embodiments 1-4 and Comparative Example 1 in PET hydrolysate, and b figure is formate salt faradic efficiency and yield of the catalytic electrode prepared in Embodiments 1-4 and Comparative Example 1 under 200 mA cm -2 current density test;

[0035] Figure 9 a figure in the PET hydrolysate before and after electrolysis is a nuclear magnetic resonance hydrogen spectrum (H NMR); b figure is a nuclear magnetic resonance hydrogen spectrum (H NMR) of the EGOR formate generated by the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Embodiment 1 under different current density tests in the PET hydrolysate; 1 1

[0036] Figure 10 ​​The EGOR formate yield and Faraday efficiency of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Example 1 of the present application were continuously tested for 6 times without replacing the catalyst, and a comparison chart of the formate yield and Faraday efficiency is shown in the following figure:

[0037] Figure 11 The stability curve of the EGOR test of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Example 1 of the present application was carried out in the PET hydrolysate as raw material at 500 mA cm -2 The stability curve of the EGOR test of the nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Example 1 of the present application was carried out in the PET hydrolysate as raw material at 500 mA cm DETAILED DESCRIPTION

[0038] In order to better illustrate the content of the present application, the following specific examples are described.

[0039] Example 1

[0040] A preparation method of a nickel-doped cobalt oxyhydroxide catalytic electrode, the process flow chart is shown as Figure 1 The following steps are included:

[0041] Step 1, add cobalt nitrate and nickel nitrate to water to configure a mixed solution with the concentration of cobalt nitrate being 100 mM and the concentration of nickel nitrate being 25 mM, and obtain a light red electrolyte;

[0042] Step 2, select a piece of 1x2 cm 2 metallic nickel foam as a working electrode, use saturated silver / silver chloride as a reference electrode, use a platinum sheet as a counter electrode, use the mixed solution of step 1 as an electrode solution, construct an electrolytic cell of a three-electrode system, and apply a constant current density of-80 mA cm -2 to the working electrode, and the surface of the metallic nickel foam substrate will quickly change color. After applying a constant current for 400 s, a dark green catalyst will tightly cover the surface of the nickel foam substrate, and a nickel-doped cobalt hydroxide pre-electrode is obtained, which is denoted as Ni-Co(OH)2 / NF;

[0043] Step 3, use the nickel-doped cobalt hydroxide pre-electrode as a working electrode, saturated silver / silver chloride as a reference electrode, and platinum as a counter electrode to assemble a three-electrode system in the PET hydrolysate, and cyclic voltammetry activation is carried out on the working electrode at 0-2V to obtain a nickel-doped cobalt oxyhydroxide catalytic electrode through electrochemical oxidation reconstruction, which is denoted as Ni-CoOOH3 / NF.

[0044] Example 2

[0045] The preparation method of this example is the same as that of Example 1, and the difference lies in that in step 1, the concentration of cobalt nitrate in the electrolyte during electrodeposition is 50 mM, and the concentration of nickel nitrate is 25 mM, and the obtained catalytic electrode is denoted as Ni-CoOOH1 / NF.

[0046] Example 3

[0047] This comparative example is the same as the preparation method of Example 1, except that in step 1, the concentration of cobalt nitrate in the electrolyte during electrodeposition is 75 mM, and the concentration of nickel nitrate is 25 mM. The obtained catalytic electrode is denoted as Ni-CoOOH2 / NF.

[0048] Example 4

[0049] This comparative example is the same as the preparation method of Example 1, except that in step 1, the concentration of cobalt nitrate in the electrolyte during electrodeposition is 125 mM, and the concentration of nickel nitrate is 25 mM. The obtained catalytic electrode is denoted as Ni-CoOOH4 / NF.

[0050] Example 5

[0051] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -40 mA cm-2. -2 .

[0052] Example 6

[0053] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -120 mA cm-2. -2 .

[0054] Example 7

[0055] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -160 mA cm-2. -2 .

[0056] Example 8

[0057] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -200 mA cm-2. -2 .

[0058] Example 9

[0059] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -80 mA cm-2for a time of 200 s. -2 .

[0060] Example 10

[0061] This example is the same as the preparation method of Example 1, except that in step 2, the constant current applied during electrodeposition is -80 mA cm-2for a time of 300 s. -2 .

[0062] Example 11

[0063] The preparation method of the embodiment is the same as that of embodiment 1, except that in step 2, a constant current of -80 mA cm-2 is applied during electrodeposition for a time of 500 s. -2

[0064] Embodiment 12

[0065] The preparation method of the embodiment is the same as that of embodiment 1, except that in step 2, a constant current of -80 mA cm-2 is applied during electrodeposition for a time of 600 s. -2

[0066] Embodiment 13

[0067] The preparation method of the embodiment is the same as that of embodiment 1, except that in step 3, the potential applied for the electrochemical oxidation restructuring of the electrode material is 0-2 V, and the oxidation restructuring time is 20 min.

[0068] Embodiment 14

[0069] The preparation method of the embodiment is the same as that of embodiment 1, except that in step 3, the potential applied for the electrochemical oxidation restructuring of the electrode material is 0-2 V, and the oxidation restructuring time is 30 min.

[0070] Comparative Example 1

[0071] The preparation method of the comparative example is the same as that of embodiment 1, except that in step 1, only cobalt nitrate with a concentration of 125 mM is present in the electrolyte during electrodeposition, and the obtained catalytic electrode is denoted as CoOOH / NF. Characterization and performance testing:

[0072] The nickel-doped cobalt hydroxide pre-electrode and the nickel-doped hydroxyl cobalt oxide electrode material of embodiment 1 were subjected to XRD analysis, respectively, as shown in Figs. a and b, the pre-electrode conforms to the Co(OH)2phase; the Ni-CoOOH3catalytic material prepared in embodiment 1 conforms to the CoOOH phase, proving that the material is successfully synthesized. Figure 2 The pre-electrode and the nickel-doped hydroxyl cobalt oxide electrode material of embodiment 1 were subjected to SEM analysis, respectively, as shown in Figs. a~b and c~d. As can be seen from the comparison of Figs. a~b and c~d, the Ni-CoOOH3material of the application has a nanosheet morphology and uniformly covers the surface of the nickel foam, and the nanosheet after electrochemical restructuring has a more thin wrinkle-like morphology, further optimizing the material activity and surface area, and fully exposing the metal catalytic sites to participate in the reaction.

[0073] Figure 3 The nickel-doped hydroxyl cobalt oxide catalytic electrode prepared in embodiment 1 was subjected to TEM characterization, according to Figs. a and b, the material has a nanosheet morphology, and the nanosheet has a more thin wrinkle-like morphology after electrochemical restructuring, further optimizing the material activity and surface area, and fully exposing the metal catalytic sites to participate in the reaction.

[0074] The nickel-doped hydroxyl cobalt oxide catalytic electrode prepared in embodiment 1 was subjected to TEM characterization, according to Figs. a and b, the material has a nanosheet morphology, and the nanosheet has a more thin wrinkle-like morphology after electrochemical restructuring, further optimizing the material activity and surface area, and fully exposing the metal catalytic sites to participate in the reaction. Figure 4 ​​​Figure a (TEM) and Figure b (HRTEM) show that Ni-CoOOH has a nanosheet morphology, and the lattice fringes shown in Figure b have an interlayer spacing of 0.220 nm, corresponding to the CoOOH (004) crystal plane.

[0075] The nickel-doped cobalt oxyhydroxide catalytic electrode prepared in Example 1 was subjected to EDS energy spectrum element distribution analysis. Figure 5 It can be seen that the Co, Ni, and O elements in the Ni-CoOOH nanosheets are uniform, and the Ni content is 2.79%, proving the successful synthesis of nickel-doped cobalt oxyhydroxide nanosheets;

[0076] X-ray photoelectron spectroscopy was performed on the nickel-doped cobalt oxyhydroxide catalytic electrode of Example 1. Figure 6 As shown in the high-resolution Co 2p spectrum of Figure a, Ni-CoOOH3 / NF has obvious Co 3+ 2p 3 / 2 (780.1eV) and Co 3+ 2p 1 / 2 (795.2eV), while the peaks at binding energies of 781.2eV and 796.9eV correspond to Co 2+ 2p 3 / 2 and Co 2+ 2p 1 / 2 The high-resolution Ni 2p spectrum in Figure b shows that Ni is mainly in the form of Ni 2+ The above confirms that the CoOOH in the catalytic electrode is successfully doped with Ni 2+ .

[0077] Application Example 1

[0078] The nickel-doped cobalt oxyhydroxide (Ni-CoOOH3 / NF) catalytic electrode prepared in Example 1 was used to construct a three-electrode test system. PET hydrolyzate was used as the electrolyte to carry out the ethylene glycol oxidation performance test. -2 After continuous electrolysis at constant current density, the anolyte was collected for product (formate) detection.

[0079] Application Example 2

[0080] The method of this application example is the same as that of application example 1, except that a constant current of 100 mA cm is applied. -2 .

[0081] Application Example 3

[0082] The method of this application example is the same as that of application example 1, except that a constant current of 200 mA cm is applied. -2 .

[0083] Application Example 4

[0084] The method of this application example is the same as that of application example 1, except that a constant current of 300 mA cm is applied. -2 .

[0085] Application Example 5

[0086] The method of this application example is the same as that of application example 1, except that a constant current of 400 mA cm is applied. -2 .

[0087] Application Example 6

[0088] The method of this application example is the same as that of application example 1, except that a constant current of 500 mA cm is applied. -2 .

[0089] Application Example 7

[0090] The method of this application example is the same as that of application example 1, except that a constant current of 600 mA cm is applied. -2 .

[0091] The Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 was tested for OER in 1M KOH and ethylene glycol oxidation in PET hydrolyzate by constructing a three-electrode system. Figure 7 and Figure 8 As shown in Figure 7a, the Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 can reach 500mA cm at a low potential of 1.38V. -2 The current density is 220mV lower than that of OER. Figure 7b is a comparison of the Faradaic efficiency and yield of formate generated by the Ni-CoOOH3 / NF catalytic electrode prepared in Example 1. -2 The Faradaic efficiency of formic acid production can reach 95% at a current density of 600 mA cm -2 The yield reached 6.05 mmol h at a current density of -1 cm -2 At the same time, the ethylene glycol oxidation performance, yield and Faraday efficiency of the catalytic electrodes prepared in Examples 1-4 and Comparative Example 1 were tested in PET hydrolyzate. Figure 8 It can be seen that the effects of the catalytic electrodes prepared in Examples 1-4 are better than the catalytic electrode prepared in Comparative Example 1. According to the comparison of the catalytic electrodes prepared in Examples 1-4, it can be seen that the Ni-CoOOH3 / NF catalytic electrode in Example 1 has the best catalytic performance.

[0092] The Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 of the present invention was subjected to EGOR 1 HNMR test, the results are as follows Figure 9The Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 was tested for its catalytic performance before and after catalysis, as shown in FIG. 1. The results show that the Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 can effectively catalyze the electrochemical conversion of glycol to formate. 1 In the H NMR comparison chart, a new formate signal peak appears at 8.3 ppm, and the intensity of the signal peak gradually increases during the increase of current density, indicating that the Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 can effectively electrochemically convert glycol to formate.

[0093] The Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 was tested for its catalytic stability. In the PET hydrolysate, the formate faradic efficiency and yield of the Ni-CoOOH3 / NF catalytic electrode were tested for 6 times without replacing the catalytic electrode, as shown in FIG. 2. The results show that the formate faradic efficiency and yield remain stable during the multiple cycle electrolysis tests, proving the excellent stability of the Ni-CoOOH3 / NF catalytic electrode. Figure 10

[0094] The Ni-CoOOH3 / NF catalytic electrode prepared in Example 1 was tested for its catalytic stability. In the PET hydrolysate, the formate faradic efficiency and yield of the Ni-CoOOH3 / NF catalytic electrode were tested for 6 times without replacing the catalytic electrode, as shown in FIG. 2. The results show that the formate faradic efficiency and yield remain stable during the multiple cycle electrolysis tests, proving the excellent stability of the Ni-CoOOH3 / NF catalytic electrode. -2 Figure 11

[0095] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.​​​

Claims

1. A nickel-doped cobalt oxyhydroxide catalytic electrode, characterized in that: The invention comprises a foam nickel substrate and nickel-doped cobalt oxyhydroxide uniformly loaded on the surface of the foam nickel substrate. The molecular formula of the nickel-doped cobalt oxyhydroxide is Ni-CoOOH, and the nickel-doped cobalt oxyhydroxide has a wrinkled nanosheet structure.

2. The nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 1, characterized in that: The main exposed surface of the nickel-doped cobalt oxyhydroxide is the (004) surface of CoOOH, and the size of the wrinkled nanosheet structure is 500 nm to 2 μm.

3. The nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 1, characterized in that: The nickel doping amount in the nickel-doped cobalt oxyhydroxide is 2.79%.

4. A method for preparing a nickel-doped cobalt oxyhydroxide catalytic electrode according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) adding cobalt salt and nickel salt into water and stirring uniformly to obtain an electrolyte; (2) using a nickel foam substrate as a working electrode, a saturated silver / silver chloride as a reference electrode, and a platinum sheet or a graphite rod as a counter electrode, placing the working electrode, the reference electrode, and the counter electrode in the electrode solution prepared in step (1), respectively, and applying a constant current to the working electrode to obtain a preset electrode; (3) Assembling a three-electrode system in a PET hydrolyzate using the pre-prepared electrode prepared in step (2) as a working electrode, saturated silver / silver chloride as a reference electrode, and a platinum sheet or graphite rod as a counter electrode, performing positive voltage cyclic voltammetry activation on the working electrode, and obtaining the catalytic electrode by electrochemical oxidation reconstruction.

5. The method for preparing a nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 4, characterized in that: In step (1), the concentration of the cobalt salt in the electrolyte is 50 to 125 mM, and the cobalt salt is calculated as moles of cobalt ions; The concentration of the nickel salt in the electrolyte is 25 mM, and the nickel salt is measured in moles of nickel ions.

6. The method for preparing a nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 4, characterized in that: In step (1), the cobalt salt is selected from at least one of cobalt nitrate, cobalt chloride, and cobalt sulfate; The nickel salt is selected from at least one of nickel nitrate, nickel chloride and nickel sulfate.

7. The method for preparing a nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 4, characterized in that: In step (2), the constant current density applied to the working electrode is -40 to -200 mA cm -2 The time for applying a constant current density to the working electrode is 200 to 600 seconds.

8. The method for preparing a nickel-doped cobalt oxyhydroxide catalytic electrode according to claim 4, characterized in that: In step (3), the voltage for performing positive voltage cyclic voltammetry activation on the working electrode is 0 to 2 V, and the time for performing positive voltage cyclic voltammetry activation on the working electrode is 10 to 30 minutes.

9. Use of the nickel-doped cobalt oxyhydroxide catalytic electrode according to any one of claims 1 to 3 or the nickel-doped cobalt oxyhydroxide catalytic electrode obtained according to the preparation method according to any one of claims 4 to 8 in the electrocatalytic regeneration of polyethylene terephthalate waste plastic to recover formate.

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