Method for preparing hydrogen peroxide by electrocatalytic oxygen reduction and preparing carboxylic acid by coupling ketone oxidation

Abstract

The invention relates to a method for preparing hydrogen peroxide by electrocatalytic oxygen reduction and preparing carboxylic acid by coupling ketone oxidation, belongs to the technical field of electrocatalysis, and solves the problems of relatively high energy consumption and / or relatively low economic value of an anode product in the existing method for preparing hydrogen peroxide by electrocatalytic oxygen reduction. The method comprises the following steps: taking a carbon catalyst electrode as a cathode, wherein catholyte comprises a sodium sulfate solution; a NiCo2O4 electrode is used as an anode, and an anolyte is a solution containing potassium hydroxide and ketone; the catholyte and the anolyte are separated by a proton exchange membrane; the cathode is subjected to an electrocatalytic oxygen reduction reaction to generate hydrogen peroxide, and the anode is subjected to an electrocatalytic ketone oxidation reaction to generate carboxylic acid. The COR reaction is used for replacing the oxygen evolution reaction (OER) of the anode in the prior art, so that energy consumption is reduced, the anode converts ketone into carboxylic acid with high added value, and the economic value of the anode product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysis, and in particular to a method for producing hydrogen peroxide by electrocatalytic oxygen reduction coupled with ketone oxidation to produce carboxylic acid. Background Art

[0002] Hydrogen peroxide (H2O2) is an important green oxidant in large-scale industrial processes and small-scale field activities, such as industrial bleaching, chemical synthesis, disinfection, and fuel cell technology. Compared with current industrial H2O2 production processes, H2O2 electrosynthesis via the two-electron oxygen reduction reaction (2e-ORR) is a promising alternative, suitable for green and sustainable H2O2 production at various scales. In the traditional 2e-ORR, the corresponding anodic reaction is the oxygen evolution reaction (OER), which has sluggish kinetics and wastes electrical energy due to its high reaction potential. Two main approaches are currently being pursued to overcome this problem. One is to mitigate energy consumption by developing advanced catalysts (to reduce the anode overpotential), and the other is to construct a "zero-gap" membrane electrode assembly (MEA) to reduce the iR drop and thus the cell voltage. Despite significant progress in these approaches, excessive overpotentials persist, especially at high current densities, and the fixed thermodynamic voltage (1.23 V), significantly limiting the reduction of electrical energy consumption in electrocatalytic synthesis. Furthermore, the economic value of the O2 product of the anodic OER is relatively low. Summary of the Invention

[0003] In view of the above analysis, the embodiments of the present invention aim to provide a method for producing hydrogen peroxide by electrocatalytic oxygen reduction coupled with ketone oxidation to produce carboxylic acid, so as to solve the problems of high energy consumption and / or low economic value of anode products in the existing electrocatalytic oxygen reduction method for producing hydrogen peroxide.

[0004] In one aspect, the present invention provides a method for electrocatalytic oxygen reduction to produce hydrogen peroxide coupled with ketone oxidation to produce carboxylic acid, the method comprising:

[0005] A carbon catalyst electrode is used as the cathode, and the cathode electrolyte comprises a sodium sulfate solution; a NiCo2O4 electrode is used as the anode, and the anolyte is a solution comprising potassium hydroxide and ketone; the cathode electrolyte and the anolyte are separated by a proton exchange membrane;

[0006] An electrocatalytic reaction is carried out, an electrocatalytic oxygen reduction reaction occurs at the cathode to generate hydrogen peroxide, and an electrocatalytic ketone oxidation reaction occurs at the anode to generate carboxylic acid.

[0007] Preferably, the carbon catalyst electrode is a derived carbon catalyst electrode, and the preparation method of the derived carbon catalyst electrode includes:

[0008] Step (1), pyrolyzing a cation exchange resin co-doped with N and O elements, and then washing and drying the pyrolysis product to obtain a derived carbon catalyst material;

[0009] Step (2), dispersing the derived carbon catalyst material in a solution containing Nafion, isopropyl alcohol and deionized water to prepare an electrode slurry;

[0010] Step (3), spraying the electrode slurry onto a carrier fluid and drying it to obtain a derived carbon catalyst electrode.

[0011] Preferably, in step (1), the cation exchange resin is a Na-type cation exchange resin.

[0012] Preferably, in step (1), the temperature of the pyrolysis treatment is 400-800°C.

[0013] Preferably, in step (1), the drying temperature is 50-100°C.

[0014] Preferably, in step (3), the carrier fluid is at least one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

[0015] Preferably, the concentration of the sodium sulfate solution is 1-2 mol / L.

[0016] Preferably, in the anolyte, the concentration of potassium hydroxide is 1-2 mol / L, and the concentration of ketone is 5-6 mmol / L.

[0017] Preferably, the ketone is at least one of cyclopentanone, cyclohexanone, cycloheptanone, acetone and butanone.

[0018] Preferably, the voltage of the electrocatalytic reaction is -0.3 to 0.4V.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] 1. This invention uses sustainable renewable electricity to convert oxygen into hydrogen peroxide and ketones into high-value-added carboxylic acids, providing an environmentally friendly, novel route for preparing carboxylic acids. The oxygen reduction reaction (ORR) coupled with the carbon oxidation reaction (COR ketone oxidation reaction) provided by this invention is highly reproducible. Replacing the anode oxygen evolution reaction (OER) in the prior art with the COR reaction helps save energy and increase the economic value of the anode product. Furthermore, the coupled system requires no special protection and can operate for extended periods of time.

[0021] 2. The cathode-derived carbon catalyst prepared by the present invention is a defect-rich, nitrogen-oxygen-doped amorphous carbon catalyst obtained by pyrolysis of commercial resin. It also has a nanoscale void structure. By forming rich defects, it improves the oxygen reduction activity, helps to reduce oxygen to the formation and adsorption of the intermediate *OOH, thereby improving the catalytic activity.

[0022] 3. In a three-electrode H cell system, the defect-rich derivative carbon catalyst can achieve a Faradaic efficiency of 90% for electrocatalytic oxygen reduction to hydrogen peroxide at 100 mA / cm 2 It can operate stably for 50 hours at a low current density; in the three-electrode system, the NiCo2O4 electrode can effectively electro-oxidize cyclohexanone into adipic acid product; in the two-electrode system, the derivative carbon catalyst electrode and the NiCo2O4 electrode are used simultaneously for oxygen reduction and ketone oxidation, which can more effectively improve the economic value of the anode product compared to the conventional coupled oxygen evolution reaction.

[0023] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0025] Figure 1 Scanning electron microscope and EDS images of the derived carbon catalyst material of Example 1.

[0026] Figure 2 These are the LSV test results of the derived carbon catalyst materials prepared in Examples 1 to 3, where (a) is a current-voltage diagram, (b) is a diagram showing the relationship between hydrogen peroxide selectivity and voltage, and (c) is a diagram showing the relationship between the number of electron transfers and voltage.

[0027] Figure 3 These are the Tafel slope test results of the derived carbon catalyst materials prepared in Examples 1 to 3.

[0028] Figure 4 These are the electrochemically active surface area test results of the derived carbon catalyst materials prepared in Examples 1 to 3, wherein (a) is the voltage-current density diagram of C400, (b) is the voltage-current density diagram of C600, (c) is the voltage-current density diagram of C800, and (d) is the capacitance value data diagram of C400, C600 and C800.

[0029] Figure 5 These are the Raman spectroscopy test results of the derived carbon catalyst materials prepared in Examples 1 to 3.

[0030] Figure 6 The constant potential electrolysis test results of Example 4 are shown.

[0031] Figure 7 This is the hydrogen nuclear magnetic resonance spectrum of the anode side substrate of Example 4.

[0032] Figure 8 Schematic diagram of the electrolytic cell structure of Example 5.

[0033] Figure 9 The constant current electrolysis test results of Example 5 are shown; (a) is a graph showing the cathode Faraday efficiency changing over time, and (b) is a graph showing the hydrogen peroxide yield changing over time. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0035] The present invention provides a method for producing hydrogen peroxide by electrocatalytic oxygen reduction coupled with ketone oxidation to produce carboxylic acid, the method comprising:

[0036] A carbon catalyst electrode is used as the cathode, and the cathode electrolyte comprises a sodium sulfate solution; a NiCo2O4 electrode is used as the anode, and the anolyte is a solution comprising potassium hydroxide and ketone; the cathode electrolyte and the anolyte are separated by a proton exchange membrane;

[0037] An electrocatalytic reaction is carried out, an electrocatalytic oxygen reduction reaction occurs at the cathode to generate hydrogen peroxide, and an electrocatalytic ketone oxidation reaction occurs at the anode to generate carboxylic acid.

[0038] Compared with the prior art, the present invention adopts the COR reaction to replace the oxygen evolution reaction (OER) at the anode in the prior art. The COR reaction voltage is lower than the OER reaction voltage (COR voltage is less than 1.23V). Therefore, the energy consumption of the COR reaction adopted in the present invention is low. In addition, the anode product of the present invention is carboxylic acid, which improves the economic value of the anode product.

[0039] In a preferred embodiment, the carbon catalyst electrode is a derived carbon catalyst electrode, and the preparation method of the derived carbon catalyst electrode comprises:

[0040] Step (1), pyrolyzing a cation exchange resin co-doped with N and O elements, and then washing and drying the pyrolysis product to obtain a derived carbon catalyst material;

[0041] Step (2), dispersing the derived carbon catalyst material in a solution containing Nafion, isopropyl alcohol and deionized water to prepare an electrode slurry;

[0042] Step (3), spraying the electrode slurry onto a carrier fluid and drying it to obtain a derived carbon catalyst electrode.

[0043] It should be noted that the cation exchange resin may be an existing commercially available cation exchange resin.

[0044] The cathode-derived carbon catalyst prepared by the present invention is a defect-rich, nitrogen-oxygen-doped amorphous carbon catalyst obtained by pyrolysis of commercial resin. It also has a nanoscale void structure, which improves the oxygen reduction activity by forming rich defects, facilitates the reduction of oxygen to the formation and adsorption of the intermediate *OOH, thereby improving the catalytic activity.

[0045] For example, in step (1), the cation exchange resin is a Na-type cation exchange resin. After pyrolysis, the Na-type cation exchange resin is acid-washed and water-washed to form a porous structure, which is conducive to oxygen diffusion and mass transfer.

[0046] For example, the cation exchange resin is CH90-Na, D001, S1567、Amberlite TM IR120 Na and Dowex TM At least one of 50WX8.

[0047] Illustratively, in step (1), the temperature of the pyrolysis treatment is 400-800° C., for example, 400° C., 500° C., 600° C., 700° C., 800° C. The temperature of the pyrolysis treatment is preferably 400° C.

[0048] Exemplarily, in step (1), the pyrolysis treatment time is 2-3 hours.

[0049] Exemplarily, the pyrolysis is performed in a nitrogen atmosphere.

[0050] Illustratively, in step (1), the cleaning comprises: sequentially cleaning the pyrolysis product with a 1 mol / L HCl solution, anhydrous ethanol, and deionized water.

[0051] Illustratively, in step (1), the drying temperature is 50-100°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C.

[0052] Illustratively, in step (1), the drying comprises: placing the pyrolysis product in a vacuum drying oven for drying overnight.

[0053] For example, in step (2), in the electrode slurry, the amount of Nafion used is 30 μL, the amount of isopropanol used is 970 μL, and the amount of the derived carbon catalyst material used is 4 mg.

[0054] Exemplarily, in step (3), the carrier fluid is at least one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

[0055] For example, in step (3), the loading amount of the derived carbon catalyst in the derived carbon catalyst electrode is 0.5 to 1 mg / cm 2 .

[0056] Exemplarily, the method for preparing a NiCo2O4 electrode includes:

[0057] (A) adding a nickel salt, a cobalt salt, ammonium fluoride, urea, and treated nickel foam to a polytetrafluoroethylene-lined hydrothermal reactor, wherein the obtained mixed solution has a nickel chloride concentration of 0.001-0.010 mol / L, a cobalt chloride concentration of 0.001-0.010 mol / L, an ammonium fluoride concentration of 1-5 mol / L, and a urea concentration of 1-5 mol / L, and the solvent used in the mixed solution is deionized water; the nickel salt is nickel chloride and / or nickel nitrate, and the cobalt salt is cobalt chloride and / or cobalt nitrate; immersing the nickel foam in the mixed solution and conducting a hydrothermal reaction at 100-140° C.;

[0058] (B) After the hydrothermal reaction, the nickel foam loaded with NiCo2O4 was removed, rinsed with anhydrous ethanol and deionized water, and dried in a vacuum oven overnight to obtain a NiCo2O4 electrode.

[0059] Illustratively, the concentration of the sodium sulfate solution is 1 to 2 mol / L.

[0060] Exemplarily, the sodium sulfate solution is an oxygen-saturated sodium sulfate solution.

[0061] Illustratively, in the anolyte, the concentration of potassium hydroxide is 1 to 2 mol / L, and the concentration of ketone is 5 to 6 mmol / L.

[0062] Exemplarily, the ketone is at least one of cyclopentanone, cyclohexanone, cycloheptanone, acetone and butanone. When the ketone is cyclopentanone, cyclohexanone or cycloheptanone, the anode product is a diacid; when the ketone is acetone or butanone, the anode product is a monocarboxylic acid.

[0063] Exemplarily, the voltage of the electrocatalytic reaction is -0.3 to 0.4V.

[0064] The method of the present invention for producing hydrogen peroxide by electrocatalytic oxygen reduction coupled with ketone oxidation to produce carboxylic acid is further illustrated below by means of specific examples.

[0065] Example 1

[0066] This example is used to prepare a derived carbon catalyst electrode and a NiCo2O4 electrode.

[0067] Preparation of a derived carbon catalyst electrode: Step (1): pyrolysis of a Na-type cation exchange resin CH90-Na (purchased from Shanghai Macklin Co., Ltd.) co-doped with N and O elements at 400° C. for 2 h, followed by washing the pyrolysis product with a 1 mol / L HCl solution, anhydrous ethanol, and deionized water, and drying the washed pyrolysis product in a vacuum drying oven at 80° C. overnight to obtain a derived carbon catalyst material C400;

[0068] Step (2): 4 mg of the derived carbon catalyst material is ultrasonically dispersed in an aqueous solution containing 30 mL of Nafion and 970 mL of isopropanol to prepare an electrode slurry; wherein the amount of Nafion is 30 microliters, the amount of isopropanol is 970 microliters, and the amount of the derived carbon catalyst material is 4 mg.

[0069] Step (3): spray the electrode slurry onto carbon paper (purchased from Cabot Corporation, brand XC72) with a catalyst loading of 0.5 mg / cm 2 The sprayed electrode was vacuum dried overnight to obtain a derived carbon catalyst electrode.

[0070] Preparation of a NiCo2O4 electrode: A mixed solution of nickel nitrate, cobalt nitrate, ammonium fluoride and urea is added to a polytetrafluoroethylene-lined hydrothermal reactor, nickel foam is immersed in the mixed solution, and a hydrothermal reaction is carried out at 120°C; the concentrations of nickel nitrate and cobalt nitrate in the mixed solution are 1 mmol / L, the concentration of urea is 1 mol / L, and the concentration of ammonium fluoride is 1 mol / L, and the solvent used for the mixed solution is deionized water; after the hydrothermal reaction is completed, the nickel foam loaded with NiCo2O4 is removed, rinsed with anhydrous ethanol and deionized water in sequence, and the obtained electrode is placed in a vacuum drying oven and dried overnight to obtain a NiCo2O4 electrode.

[0071] Example 2-Example 3

[0072] Similar to Example 1, except that the pyrolysis temperatures of the cation exchange resins during the preparation of the derived carbon catalyst electrodes were 600° C. and 800° C., respectively, to obtain derived carbon catalyst materials C600 and C800.

[0073] The performance of the derived carbon catalyst materials prepared in Examples 1 to 3 was tested below.

[0074] Figure 1 Scanning electron microscopy and EDS images of the derived carbon catalyst material of Example 1. It can be seen that the C400 catalyst has a rich pore structure, which facilitates the rapid diffusion of oxygen and increases the contact area between the reaction substrate and the catalyst. EDS test results indicate that the C400 derived carbon catalyst contains nitrogen and oxygen doping.

[0075] The oxygen reduction activity of the derived carbon catalyst materials prepared in Examples 1 to 3 was tested: 4 mg of the derived carbon catalyst was weighed and mixed with 30 μl of Nafion, 370 μl of deionized water, and 600 μl of isopropanol, followed by ultrasonication to form an ink. 9 μl of the ink was dropped onto the disk electrode of the ring disk electrode. After drying, the LSV test was performed in an oxygen-saturated 0.1 M PBS solution. The results are shown in FIG. Figure 2 As shown, it can be seen that the oxygen reduction performance of the three groups of derivative carbon catalysts in neutral electrolyte is excellent, among which the C400 catalyst has the best performance, with a hydrogen peroxide selectivity of 92% and an electron transfer number close to 2, indicating that the catalyst has excellent two-electron oxygen reduction activity.

[0076] The reaction kinetics and electrochemically active surface area of ​​the derived carbon catalyst materials prepared in Test Examples 1-3 were as follows: a three-electrode system was composed of a derived carbon electrode as the cathode, an iridium-titanium mesh electrode as the anode, and a silver / silver chloride electrode as the reference electrode. The cathode tank electrolyte was an oxygen-saturated 1 M sodium sulfate solution, the anode tank electrolyte was a 0.5 M sulfuric acid solution, the cathode and the anode were separated by a proton exchange membrane, and the voltage range was -0.5 to 1.3 V (vs RHE). Figure 3 The Tafel slope test results show that the C400 catalyst has the best reaction kinetics, with a Tafel slope of 156.1 mVdec-1, which is smaller than that of C600 and C800. Figure 4 The electrochemical active surface area test results show that the C400 catalyst has the largest electrochemical active surface area, and its capacitance value Cdl is 0.44mF cm-2, which is greater than the capacitance values ​​of C600 and C800.

[0077] The Raman spectra of the derived carbon catalyst materials prepared in Test Examples 1 to 3 are as follows: Figure 5 As shown, the results show that as the pyrolysis temperature increases, the defect level of the derived carbon catalyst begins to decrease. The ID / IG of the C400 catalyst is 4.3, which is greater than that of C600 and C800, indicating that C400 has more defects and improves the oxygen reduction activity by forming abundant defects, which helps to reduce oxygen to the formation and adsorption of the intermediate *OOH, thereby improving the catalytic activity.

[0078] The performance of the NiCo2O4 electrode prepared in Example 1 was tested below: Figure 6This is the XRD test result of NiCo2O4 electrode, which shows that NiCo2O4 electrode was successfully synthesized, which is consistent with the PDF card.

[0079] Example 4

[0080] This embodiment provides a method for electrocatalytic oxygen reduction to produce hydrogen peroxide coupled with ketone oxidation to produce carboxylic acid, the method comprising:

[0081] The C400-derived carbon catalyst electrode prepared in Example 1 was used as the cathode, and the NiCo2O4 electrode prepared in Example 1 was used as the anode. The cathode served as the working electrode, and the reference electrode was a silver / silver chloride electrode. The cathode electrolyzer solution consisted of a 1 mol / L sodium sulfate solution saturated with oxygen, and the anolyte was a mixed aqueous solution containing 1 mol / L potassium hydroxide and 5 mmol / L cyclohexanone. The cathode and anode were separated by a proton exchange membrane. Constant-potential electrolysis was performed for 5 hours at a constant potential voltage of -0.3 to 0.1 V (RHE).

[0082] like Figure 6 As shown, the Faradaic efficiency of hydrogen peroxide generated by the cathode at different voltages is around 90%. Figure 7 H NMR spectrum showed that the cyclohexanone substrate on the anode side was gradually converted into adipic acid.

[0083] Example 5

[0084] This embodiment provides a method for electrocatalytic oxygen reduction to produce hydrogen peroxide coupled with ketone oxidation to produce carboxylic acid, the method comprising:

[0085] like Figure 8 As shown, a two-electrode system was formed using the C400-derived carbon catalyst electrode prepared in Example 1 as the cathode and the NiCo2O4 electrode prepared in Example 1 as the anode. The cathode tank electrolyte was a 1 mol / L sodium sulfate solution saturated with oxygen, and the anode tank electrolyte was a mixed solution of 1 M potassium hydroxide and 5 mM cyclohexanone. The cathode and anode were separated by a proton exchange membrane. At a constant current of 100 mA / cm 2 The constant current electrolysis test was carried out under the conditions of 50 hours. At the same time, the cathode was tested for constant current stability. The test results are as follows: Figure 9 It was shown that after 50 hours of stability testing, the Faradaic efficiency of the cathode could be maintained at 85% to 93%, demonstrating high catalytic activity and stability.

[0086] Comparative Example 1

[0087] This comparative example provides a method similar to Example 5 for electrocatalytic oxygen reduction to hydrogen peroxide coupled with ketone oxidation to carboxylic acid, except that the cathode is a carbon black catalyst electrode. After 50 hours of stability testing, the cathode's Faradaic efficiency remained between 70% and 80%.

[0088] According to the comparison of the results of Comparative Example 1 and Example 5, the use of the derivative carbon catalyst electrode of the present invention can effectively improve the Faraday efficiency of the cathode, and the derivative carbon catalyst electrode of the present invention has higher catalytic activity and stability.

[0089] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for producing hydrogen peroxide by electrocatalytic oxygen reduction coupled with ketone oxidation to produce carboxylic acid, characterized in that: The method comprises: A carbon catalyst electrode is used as a cathode, and a cathode electrolyte comprises a sodium sulfate solution; a NiCo2O4 electrode is used as an anode, and an anolyte is a solution comprising potassium hydroxide and ketone; the cathode electrolyte and the anolyte are separated by a proton exchange membrane; An electrocatalytic reaction is carried out, wherein an electrocatalytic oxygen reduction reaction occurs at the cathode to generate hydrogen peroxide, and an electrocatalytic ketone oxidation reaction occurs at the anode to generate carboxylic acid.

2. The method according to claim 1, characterized in that The carbon catalyst electrode is a derived carbon catalyst electrode, and the preparation method of the derived carbon catalyst electrode includes: Step (1), pyrolyzing a cation exchange resin co-doped with N and O elements, and then washing and drying the pyrolysis product to obtain a derived carbon catalyst material; Step (2), dispersing the derived carbon catalyst material in a solution containing Nafion, isopropyl alcohol and deionized water to prepare an electrode slurry; Step (3), spraying the electrode slurry onto a carrier fluid and drying it to obtain a derived carbon catalyst electrode.

3. The method according to claim 2, characterized in that In step (1), the cation exchange resin is a Na-type cation exchange resin.

4. The method according to claim 2, characterized in that In step (1), the temperature of the pyrolysis treatment is 400-800°C.

5. The method according to claim 2, characterized in that In step (1), the drying temperature is 50-100°C.

6. The method according to claim 2, characterized in that In step (3), the carrier fluid is at least one of carbon cloth, hydrophilic carbon paper, hydrophobic carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass.

7. The method according to claim 1, characterized in that The concentration of the sodium sulfate solution is 1-2 mol / L.

8. The method according to claim 1, characterized in that In the anolyte, the concentration of potassium hydroxide is 1-2 mol / L, and the concentration of ketone is 5-6 mmol / L.

9. The method according to claim 1, characterized in that The ketone is at least one of cyclopentanone, cyclohexanone, cycloheptanone, acetone and butanone.

10. The method according to claim 1, characterized in that The voltage of the electrocatalytic reaction is -0.3 to 0.4V.

Images