NiM-OOH electrocatalytic material loaded on foamed nickel as well as preparation method and application of NiM-OOH electrocatalytic material

Abstract

The invention is suitable for the technical field of electro-catalytic materials, and provides a nickel foam loaded NiM-OOH electro-catalytic material and a preparation method and application thereof.The preparation method comprises the following steps that cut nickel foam is sequentially treated with nitric acid, ethyl alcohol and deionized water; dissolving nickel chloride hexahydrate, M chloride and diammonium hydrogen phosphate in deionized water, then adding the treated foamed nickel, heating for reaction, cooling to room temperature after the reaction is finished, collecting a product, washing with ethanol and deionized water, and drying; and activating the dried product in a potassium hydroxide solution to obtain the nickel foam loaded NiM-OOH electrocatalytic material. The NiM-OOH loaded on the foamed nickel is synthesized by heating the simple and easily available raw materials, the preparation method is simple and convenient, the raw materials are easy to obtain and repeat, the cost is easy to control in industrial production, the method is suitable for large-scale production, the material quality is stable, and the polylactic acid waste can produce high-added-value products, namely potassium acetate and hydrogen.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalytic materials, and in particular relates to a NiM-OOH electrocatalytic material loaded on nickel foam, a preparation method and an application thereof. Background Art

[0002] Polylactic acid is a representative renewable polymer material that plays a pivotal role in the chemical industry. However, the post-treatment of polylactic acid waste is receiving more and more attention. Current treatment methods include natural decomposition, composting, incineration, etc., but they will produce a large amount of carbon dioxide, resulting in carbon emissions and resource waste. Therefore, how to deal with polylactic acid waste while producing high value-added products is of great significance to environmental protection and resource utilization.

[0003] Electrocatalytic oxidation of small molecules is a promising method for treating polylactic acid waste. However, research on the electrooxidation of potassium lactate is in its infancy. The lack of selectivity of the target product and its strong alkaline environment make product separation and purification challenging, thus limiting the production of high-purity target products and making these reactions not yet industrial-scale. In addition, the subsequent treatment must not only ensure the high purity of the final product potassium acetate, but also ensure that the economic cost of the treatment process is minimized, which makes the implementation of this process on an industrial scale a huge challenge. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a NiM-OOH electrocatalytic material loaded on nickel foam, aiming to solve the problems raised in the above background technology.

[0005] The embodiment of the present invention is implemented in such a way that a NiM-OOH electrocatalytic material is loaded on a nickel foam, wherein M is one of Co, Mn, Fe, Zn, and Cr.

[0006] Another object of the embodiment of the present invention is to provide a method for preparing a NiM-OOH electrocatalytic material supported on nickel foam, comprising the following steps:

[0007] The cut nickel foam is treated with nitric acid, ethanol and deionized water in sequence;

[0008] Dissolve nickel chloride hexahydrate, M chloride and diammonium hydrogen phosphate in deionized water, wherein M is one of Co, Mn, Fe, Zn and Cr, add the treated nickel foam, heat to react, cool to room temperature after the reaction, collect the product, wash with ethanol and deionized water, and then dry;

[0009] The dried product is activated in a potassium hydroxide solution to obtain a NiM-OOH electrocatalytic material supported on nickel foam.

[0010] Preferably, in the step of treating the cut nickel foam with nitric acid, ethanol and deionized water in sequence, the concentration of the nitric acid is 1-1.2 mol / L, and the treatment is ultrasonic treatment for 10-15 min.

[0011] Preferably, in the step of heating to react, oil bath heating is adopted, the temperature is 65-75° C., and the time is 2.5-3.5 h.

[0012] Preferably, in the step of activating the dried product in a potassium hydroxide solution, the concentration of the potassium hydroxide solution is 1-1.2 mol / L.

[0013] Another object of an embodiment of the present invention is to provide an application of a NiM-OOH electrocatalytic material supported on nickel foam in the electrooxidation of potassium lactate to prepare potassium acetate.

[0014] Preferably, the electro-oxidation of potassium lactate to prepare potassium acetate is carried out in an H-type electrolytic cell, the NiM-OOH electrocatalytic material loaded on the nickel foam is used as the working electrode, the platinum sheet is used as the counter electrode, the reference electrode is a mercury / mercury oxide electrode, the anolyte is potassium hydroxide and potassium lactate, the catholyte is potassium hydroxide, and the potassium lactate is driven to undergo an electro-oxidation reaction when power is turned on.

[0015] Preferably, the potential applied during the power-on is 1.2-1.6 V compared to a standard hydrogen electrode.

[0016] Another object of an embodiment of the present invention is to provide an electrosynthesis system for converting polylactic acid waste into potassium acetate, comprising:

[0017] An alkali treatment device for treating polylactic acid waste to obtain potassium lactate solution;

[0018] An electrolysis device connected to the alkali treatment device, wherein the electrolysis device is provided with the NiM-OOH electrocatalytic material loaded on the nickel foam, and uses a potassium lactate solution as an electrolyte, and is used to oxidize the potassium lactate solution into potassium acetate at the anode and generate hydrogen at the cathode;

[0019] The acid treatment device and the drying device are connected to the electrolysis device and are used to adjust the pH value of the electrolyte and then dry the electrolyte to obtain solid potassium acetate.

[0020] Another object of the embodiment of the present invention is to provide an electrosynthesis method for converting polylactic acid waste into an electrosynthesis system for potassium acetate, comprising the following steps:

[0021] Adding polylactic acid waste into a reaction tank in an alkali treatment device and treating it with a potassium hydroxide solution to obtain a potassium lactate solution;

[0022] A potassium lactate solution is passed into an electrolysis device as an electrolyte, and under the catalytic action of the NiM-OOH electrocatalytic material loaded on the nickel foam, it is oxidized to potassium acetate at the anode and generates hydrogen at the cathode;

[0023] The pH value of the electrolyte is adjusted by an acid treatment device, and then dried by a drying device to obtain solid potassium acetate.

[0024] The embodiment of the present invention uses simple and readily available raw materials to synthesize NiM-OOH loaded on nickel foam by heating. The preparation method is simple, the required equipment and raw materials are abundant and inexpensive, easy to obtain and easy to repeat, easy to control costs in industrial production, suitable for large-scale production, and stable material quality;

[0025] The NiM-OOH loaded on the nickel foam prepared in the embodiment of the present invention can be used as a working electrode to drive the electro-oxidation reaction of potassium lactate to generate potassium acetate when powered. Furthermore, it can be applied in an industrial-grade electrosynthesis system to produce high-value-added products such as potassium acetate and hydrogen from polylactic acid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of an electrosynthesis system for converting polylactic acid waste into potassium acetate provided in an embodiment of the present invention;

[0027] Figure 2 This is a comparison diagram of linear sweep voltammetry curves of samples prepared in Example 1 of the present invention and Comparative Example 1 in a mixed electrolyte of potassium hydroxide and potassium lactate;

[0028] Figure 3 A physical picture of an industrial-grade electrosynthesis system for producing high-value-added product potassium acetate from polylactic acid waste provided in Example 6 of the present invention;

[0029] Figure 4 A physical diagram of an electrolysis device provided in Example 6 of the present invention;

[0030] Figure 5 This is a graph showing the changes in the concentrations of potassium lactate, potassium acetate and potassium pyruvate over time during the reaction cycle provided in Example 6 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] A NiM-OOH electrocatalytic material loaded on nickel foam, the preparation method of which comprises the following steps:

[0033] S1. Cut the nickel foam NF into 25-100 cm 2 According to the specifications, the cut nickel foam was ultrasonicated in 1 mol / L nitric acid for 10 min, in ethanol for 10 min, and in deionized water for 10 min.

[0034] S2, dissolving nickel chloride hexahydrate, M chloride and diammonium hydrogen phosphate in deionized water, taking nickel chloride hexahydrate (7.92-31.68 g), M chloride (M is one of Co, Mn, Fe, Zn, Cr) (1.14-8.88 g), diammonium hydrogen phosphate (6.58-26.33 g) and water (0.5-2 L), adding the treated nickel foam to the beaker solution, heating, after the reaction is completed and cooled to room temperature, collecting the product, washing it with ethanol and deionized water, and then drying it;

[0035] S3, activating the product in a 1 mol / L potassium hydroxide solution to obtain a NiM-OOH electrocatalytic material supported on nickel foam;

[0036] The above-mentioned electrocatalytic material is applied in the electrocatalytic oxidation of potassium lactate, which specifically includes the following steps: an H-type electrolytic cell is set as an electrochemical reaction cell, a three-electrode system is adopted, a NiM-OOH electrocatalytic material loaded on nickel foam is used as a working electrode, a reference electrode is a mercury-mercury oxide electrode, a counter electrode is a platinum sheet, the electrolyte is 1 mol / L potassium hydroxide solution and 0.4 mol / L potassium lactate solution, and the potential applied when power is turned on is 1.2-1.6 V compared to the standard hydrogen electrode.

[0037] An electrosynthetic system for converting polylactic acid waste into potassium acetate, such as Figure 1 As shown, it includes the following structures:

[0038] Alkali treatment device, including a reaction tank; electrolysis device, including an alkaline water electrolysis tank, a gas-liquid separator, a heating and temperature control system; acid treatment device, including a reaction tank; drying device, using a spray dryer;

[0039] The specific operations are as follows:

[0040] In an industrial-grade electrosynthesis system, polylactic acid waste is added to a reaction tank of an alkali treatment device, treated with a potassium hydroxide solution to obtain a potassium lactate solution, and then introduced into an electrolysis device, where it is oxidized to potassium acetate at the anode under the action of a NiM-OOH electrocatalytic material loaded on nickel foam, and hydrogen is generated at the cathode. The pH is then adjusted by an acid treatment device, and then dried by a spray dryer to obtain solid potassium acetate.

[0041] The electrolysis device can be an industrial-scale electrolytic cell, which is the core component of the industrial-grade electrosynthesis system. It includes 18 independent electrolytic cells with a total electrolyte volume of 10 L. In addition, the working areas of the anode and cathode are both 1386 cm 2 , using NiM-OOH electrocatalytic material loaded on nickel foam as anode and commercially available nickel wire mesh as cathode;

[0042] During the system cycle (current density is 2000 A / m 2 ), 320 g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 h to obtain 232 L of hydrogen; the pH of the electrolyte was then adjusted with acetic acid, and finally the electrolyte was spray-dried to obtain 1200 g of pure solid potassium acetate. The purity of the potassium acetate product was over 97%. In this process, the system treated 500 L of potassium lactate solution and generated 11.6 standard m 3 The electrocatalytic material showed ultra-high stability at 2000 A / m 2 The test results were shown in Table 2. The test results were maintained for more than 50 cycles (100 h).

[0043] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0044] Example 1: A NiM-OOH (M=Co) electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0045] Cut the 78.5 cm 2 The circular nickel foam was treated with nitric acid, ethanol and deionized water in sequence; analytical grade nickel chloride hexahydrate (24.87 g), cobalt chloride hexahydrate (6.21 g) and diammonium hydrogen phosphate (20.67 g) were selected as raw materials and dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain NiM-OOH (M=Co) electrocatalytic material loaded on nickel foam.

[0046] Example 2: A NiM-OOH (M=Mn) electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0047] Cut the 78.5 cm 2The round nickel foam of 1.5 m was treated with nitric acid, ethanol and deionized water in sequence; the raw materials were selected as analytical grade nickel chloride hexahydrate (24.87 g), manganese chloride tetrahydrate (5.17 g) and diammonium hydrogen phosphate (20.67 g), which were dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain NiM-OOH (M=Mn) electrocatalytic material loaded on nickel foam.

[0048] Example 3: A NiM-OOH (M=Fe) electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0049] Cut the 78.5 cm 2 The circular nickel foam was treated with nitric acid, ethanol and deionized water in sequence; analytical grade nickel chloride hexahydrate (24.87 g), ferrous chloride tetrahydrate (5.21 g) and diammonium hydrogen phosphate (20.67 g) were selected as raw materials and dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain NiM-OOH (M=Fe) electrocatalyst material supported on nickel foam.

[0050] Example 4: A NiM-OOH (M=Zn) electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0051] Cut the 78.5 cm 2 The circular nickel foam was treated with nitric acid, ethanol and deionized water in sequence; analytical grade nickel chloride hexahydrate (24.87 g), anhydrous zinc chloride (3.57 g) and diammonium hydrogen phosphate (20.67 g) were selected as raw materials and dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain NiM-OOH (M=Zn) electrocatalytic material loaded on nickel foam.

[0052] Example 5: A NiM-OOH (M=Cr) electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0053] Cut the 78.5 cm 2 The circular nickel foam was treated with nitric acid, ethanol and deionized water in sequence; analytical grade nickel chloride hexahydrate (24.87 g), chromium chloride hexahydrate (6.97 g) and diammonium hydrogen phosphate (20.67 g) were selected as raw materials and dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain NiM-OOH (M=Cr) electrocatalytic material loaded on nickel foam.

[0054] Comparative Example 1: A Ni-OOH electrocatalytic material loaded on nickel foam, the preparation method of which is as follows:

[0055] Cut the 78.5 cm 2 The circular nickel foam was treated with nitric acid, ethanol and deionized water in sequence; analytical grade nickel chloride hexahydrate (31.10 g) and diammonium hydrogen phosphate (20.67 g) were selected as raw materials and dissolved in deionized water (1.57 L); the treated nickel foam was added to the solution and heated in an oil bath at 70 °C for 3 h; after the reaction was completed and cooled to room temperature, the product was collected, washed with ethanol and deionized water, and then dried to obtain the product; the above product was activated in 1 mol / L potassium hydroxide solution to obtain a Ni-OOH electrocatalytic material loaded on nickel foam.

[0056] Performance Testing:

[0057] The samples prepared in Example 1 and Comparative Example 1 were cut into appropriate specifications and used as electrocatalytic materials to test their performance in electro-oxidation of potassium lactate to produce high-value potassium acetate. An H-type electrolytic cell was set as an electrochemical reaction cell, and a three-electrode system was adopted. The anode chamber and the cathode chamber were separated by an anion exchange membrane. The two samples were used as working electrodes, platinum sheets were used as counter electrodes, and mercury / mercury oxide electrodes were used as reference electrodes. The potential applied when power was turned on was 1.2-1.6 V compared to the standard hydrogen electrode, and the following was obtained: Figure 2 The linear sweep voltammetric curve shown in FIG. 1 shows that the NiM-OOH electrocatalytic material loaded on the nickel foam prepared in the embodiment of the present invention reaches 403 mA / cm in 1 mol / L potassium hydroxide and 0.4 mol / L potassium lactate solution. 2 The current density is only 1.4 V (vs. standard hydrogen electrode).

[0058] Example 6: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, such as Figure 3As shown, the specific process is as follows:

[0059] Polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, and then in an electrolysis device (such as Figure 4 The anode of the reactor (shown) is oxidized to potassium acetate, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0060] During the system cycle (current density is 2000 A / m 2 ), 320 g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 h to obtain 232 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. The electrolyte was finally spray-dried to obtain 1200 g of pure solid potassium acetate. After testing, the purity of the potassium acetate product obtained exceeded 97%. The concentration changes of potassium lactate, potassium acetate and potassium pyruvate over time during the reaction cycle are shown in the figure below. Figure 5 shown.

[0061] Example 7: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0062] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0063] During the system cycle (current density is 200 A / m 2 ), 32g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 h to obtain 22 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 117g of pure solid potassium acetate. After testing, the purity of the potassium acetate product exceeded 96%.

[0064] Example 8: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0065] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0066] During the cycle of the system (current density is 500 A / m 2 ), 80g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 hours to obtain 55 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 295g of pure solid potassium acetate. After testing, the purity of the potassium acetate product obtained exceeded 96%.

[0067] Example 9: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0068] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0069] During the system cycle (current density is 1000 A / m 2 ), 160g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 hours to obtain 115 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 602 g of pure solid potassium acetate. After testing, the purity of the potassium acetate product obtained exceeded 97%.

[0070] Example 10: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0071] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0072] During the system cycle (current density is 3000 A / m 2 ), 480g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 hours to obtain 350 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 1790 g of pure solid potassium acetate. After testing, the purity of the potassium acetate product exceeded 97%.

[0073] Example 11: An industrial-grade electrosynthesis system for producing high-value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0074] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0075] During the system cycle (current density is 4000 A / m 2 ), 640 g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 h to obtain 469 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 2430 g of pure solid potassium acetate. After testing, the purity of the potassium acetate product exceeded 96%.

[0076] Example 12: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0077] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0078] During the system cycle (current density is 5000 A / m 2 ), 800 g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 h to obtain 575 L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 2990 g of pure solid potassium acetate. After testing, the purity of the potassium acetate product exceeded 99%.

[0079] Example 13: An industrial-grade electrosynthesis system for producing high value-added product potassium acetate from polylactic acid waste, the specific process of which is as follows:

[0080] In the industrial-grade electrosynthesis system, polylactic acid is first treated with potassium hydroxide solution to obtain potassium lactate solution, then oxidized to potassium acetate at the anode, and hydrogen is generated at the cathode; after acid treatment and drying, pure solid potassium acetate is obtained;

[0081] During the system cycle (current density is 6000 A / m 2 ), 960g of polylactic acid waste was treated with potassium hydroxide solution and electrolyzed for 2 hours to obtain 704L of hydrogen. The pH of the electrolyte was then adjusted with acetic acid. Finally, the electrolyte was spray-dried to obtain 3615g of pure solid potassium acetate. After testing, the purity of the potassium acetate product exceeded 98%.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A NiM-OOH electrocatalytic material loaded on nickel foam, characterized in that: The M is one of Co, Mn, Fe, Zn and Cr.

2. A method for preparing the NiM-OOH electrocatalytic material supported on nickel foam as claimed in claim 1, characterized in that: The following steps are involved: The cut nickel foam is treated with nitric acid, ethanol and deionized water in sequence; Dissolve nickel chloride hexahydrate, M chloride and diammonium hydrogen phosphate in deionized water, wherein M is one of Co, Mn, Fe, Zn and Cr, add the treated nickel foam, heat to react, cool to room temperature after the reaction, collect the product, wash with ethanol and deionized water, and then dry; The dried product is activated in a potassium hydroxide solution to obtain a NiM-OOH electrocatalytic material supported on nickel foam.

3. The method for preparing the NiM-OOH electrocatalytic material loaded on nickel foam according to claim 2, characterized in that: In the step of treating the cut nickel foam with nitric acid, ethanol and deionized water in sequence, the concentration of the nitric acid is 1-1.2 mol / L, and the treatment is ultrasonic treatment for 10-15 min.

4. The method for preparing the NiM-OOH electrocatalytic material loaded on nickel foam according to claim 2, characterized in that: In the step of heating the reaction, an oil bath is used for heating at a temperature of 65-75° C. for 2.5-3.5 h.

5. The method for preparing the NiM-OOH electrocatalytic material loaded on nickel foam according to claim 2, characterized in that: In the step of activating the dried product in a potassium hydroxide solution, the concentration of the potassium hydroxide solution is 1-1.2 mol / L.

6. Use of the NiM-OOH electrocatalytic material supported on nickel foam as claimed in claim 1 in preparing potassium acetate by electrooxidation of potassium lactate.

7. The use according to claim 6, characterized in that: The electro-oxidation of potassium lactate to prepare potassium acetate is carried out in an H-type electrolytic cell, the NiM-OOH electrocatalytic material loaded on the nickel foam is used as a working electrode, a platinum sheet is used as a counter electrode, a mercury / mercuric oxide electrode is selected as a reference electrode, the anolyte is potassium hydroxide and potassium lactate, the catholyte is potassium hydroxide, and potassium lactate is driven to undergo an electro-oxidation reaction when power is turned on.

8. The use according to claim 7, characterized in that: The potential applied during the power-on is 1.2-1.6 V compared to a standard hydrogen electrode.

9. An electrosynthetic system for converting polylactic acid waste into potassium acetate, characterized in that: include: An alkali treatment device for treating polylactic acid waste to obtain potassium lactate solution; An electrolysis device connected to the alkali treatment device, wherein the electrolysis device is provided with the NiM-OOH electrocatalytic material supported on the nickel foam as claimed in claim 1, and a potassium lactate solution is used as an electrolyte to oxidize the potassium lactate solution into potassium acetate at the anode and generate hydrogen at the cathode; The acid treatment device and the drying device are connected to the electrolysis device and are used to adjust the pH value of the electrolyte and then dry the electrolyte to obtain solid potassium acetate.

10. An electrosynthesis method for converting polylactic acid waste into potassium acetate according to claim 9, characterized in that: The following steps are involved: Adding polylactic acid waste into a reaction tank in an alkali treatment device and treating it with a potassium hydroxide solution to obtain a potassium lactate solution; A potassium lactate solution is passed into an electrolysis device as an electrolyte, and under the catalytic action of the NiM-OOH electrocatalytic material loaded on the nickel foam, it is oxidized to potassium acetate at the anode and generates hydrogen at the cathode; The pH value of the electrolyte is adjusted by an acid treatment device, and then dried by a drying device to obtain solid potassium acetate.

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