Electrocatalytic reaction system and method for preparing hydrogen peroxide through electrocatalysis

Abstract

The invention relates to an electro-catalysis reaction system and a method for preparing hydrogen peroxide through electro-catalysis. The system comprises a fuel cell reaction part and a normal-pressure plasma generation part used for providing normal-pressure plasma for the fuel cell reaction part. Wherein the fuel cell reaction part comprises a cathode membrane electrode assembly and an anode membrane electrode assembly, and the cathode membrane electrode assembly is provided with a through hole; the atmospheric pressure plasma generating part comprises a cylindrical central electrode and a tubular outer electrode, an insulating layer is arranged between the central electrode and the outer electrode, a cavity for accommodating plasma working gas is formed between the central electrode and the insulating layer, and the insulating layer extends into the through hole. The electrocatalytic reaction system disclosed by the invention can effectively improve the catalytic efficiency of preparing hydrogen peroxide by electrocatalytic reduction of oxygen-containing gas and the yield of hydrogen peroxide.

Description

Technical Field

[0001] The present disclosure relates to the field of electrocatalysis technology, and in particular, to an electrocatalytic reaction system and an electrocatalytic method for producing hydrogen peroxide. Background Art

[0002] Hydrogen peroxide (H2O2) is an environmentally friendly oxidant that is widely used in industry and households such as pulp and textile bleaching, wastewater treatment, chemical synthesis, etc. It is one of the most important chemicals in the world. At present, H2O2 is mainly produced on a large scale in industry through the anthraquinone method, in which the anthraquinone molecules are hydrogenated and oxidized in sequence, and then extracted and distilled to finally obtain high-concentration H2O2. This is a multi-step, energy-intensive process, and the high-concentration H2O2 obtained may cause safety problems during storage and transportation. Therefore, in recent years, the academic community has been constantly exploring greener, safer and in-situ strategies for generating low-concentration H2O2. Electrocatalytic two-electron oxygen reduction (2e - The synthesis of H2O2 by ORR is a promising alternative method, but the reaction kinetics of the ORR process are slow, which reduces the yield of H2O2. In addition, the test system of the traditional H-type electrolyzer is usually limited by oxygen mass transfer, resulting in extremely low H2O2 conversion activity. Summary of the invention

[0003] The purpose of the present disclosure is to provide an electrocatalytic reaction system and an electrocatalytic method for producing hydrogen peroxide, so as to improve the catalytic efficiency and yield of hydrogen peroxide in the electrocatalytic reaction for producing hydrogen peroxide.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the present disclosure provides an electrocatalytic reaction system, which includes a fuel cell reaction part and a normal-pressure plasma generating part for providing normal-pressure plasma to the fuel cell reaction part; wherein the fuel cell reaction part includes a cathode membrane electrode assembly and an anode membrane electrode assembly, and the cathode membrane electrode assembly has a through hole; the normal-pressure plasma generating part includes a cylindrical central electrode and a tubular outer electrode, an insulating layer is provided between the central electrode and the outer electrode, a cavity for accommodating a plasma working gas is formed between the central electrode and the insulating layer, and the insulating layer extends into the through hole.

[0005] Optionally, the central electrode is coaxially arranged with the outer electrode;

[0006] The diameter of the central electrode is 1 to 5 mm;

[0007] The inner diameter of the outer electrode is 10 to 20 mm, and the difference between the outer diameter and the inner diameter of the outer electrode is 2 to 5 mm;

[0008] The thickness of the insulating layer is 3-5 mm.

[0009] Optionally, both ends of the insulating layer extend beyond the end of the outer electrode, and a gas inlet is provided at one end of the insulating layer away from the cathode membrane electrode assembly;

[0010] In the extension direction of the central electrode, the spacing distance between one end of the central electrode close to the cathode membrane electrode assembly and the cathode membrane electrode assembly is 0.5 to 5 cm.

[0011] Optionally, the material of the center electrode is at least one of stainless steel, tungsten, thorium oxide-tungsten and cerium oxide-tungsten;

[0012] The material of the outer electrode is at least one of copper, zirconium and silver;

[0013] The insulating layer is made of at least one of glass, ceramic and resin.

[0014] Optionally, the cathode membrane electrode assembly comprises a cathode catalyst layer, a cathode chamber and a cathode gas diffusion layer which are stacked in sequence, the through hole is opened in the cathode catalyst layer, and the external electrode abuts against the surface of the cathode catalyst layer;

[0015] The anode membrane electrode assembly comprises an anode catalyst layer, an anode chamber and an anode gas diffusion layer which are stacked in sequence. The anode gas diffusion layer is close to the cathode gas diffusion layer. A proton exchange membrane is arranged between the cathode gas diffusion layer and the anode gas diffusion layer.

[0016] Optionally, the cathode catalyst layer contains a cathode catalyst and a perfluorosulfonic acid resin; wherein the weight ratio of the cathode catalyst to the perfluorosulfonic acid resin is (3-15):1; the cathode catalyst is a nitrogen-doped carbon material, and the nitrogen content of the carbon material is 0.01-5 weight % based on the total weight of the carbon material;

[0017] The anode catalyst layer contains an anode catalyst; the anode catalyst is at least one selected from platinum, carbon-supported platinum and carbon-supported platinum alloy;

[0018] The cathode chamber and the anode chamber contain electrolytes respectively, and the electrolyte is at least one selected from sulfuric acid solution, potassium hydroxide solution and perchloric acid solution;

[0019] The cathode gas diffusion layer and the anode gas diffusion layer are each independently carbon paper and / or carbon cloth;

[0020] The proton exchange membrane is at least one selected from Nafion membrane, sulfonated polystyrene proton membrane and sulfonated polybenzimidazole proton membrane.

[0021] Optionally, the system further comprises a power source connected between the central electrode and the outer electrode, and the outer electrode is partially grounded.

[0022] Optionally, the insulating layer and the through hole are fixed and sealed by a curing agent, and the curing agent is at least one selected from epoxy resin, acrylic resin and polyurethane.

[0023] In a second aspect of the present disclosure, a method for electrocatalytically producing hydrogen peroxide using the system described in the first aspect of the present disclosure is provided, the method comprising:

[0024] Allowing a plasma working gas to enter the atmospheric pressure plasma generating part for ionization to obtain oxygen plasma; wherein the plasma working gas is an oxygen-containing gas;

[0025] The oxygen plasma is allowed to enter the fuel cell reaction part through the through hole to perform an electrocatalytic reaction to obtain hydrogen peroxide.

[0026] Optionally, the oxygen-containing gas is a mixed gas of oxygen and helium, wherein the volume ratio of the oxygen to the helium is (5-1):1;

[0027] The flow rate of the oxygen-containing gas is 1 to 50 SLM;

[0028] The ionization conditions include: AC voltage of 1 to 30 kV and frequency of 0.5 to 20 kHz;

[0029] The conditions of the electrocatalytic reaction include: a constant voltage of 0.65 to 1.1 V and a time of 1 to 4 hours.

[0030] Through the above technical scheme, the electrocatalytic reaction system of the present invention combines the fuel cell reaction part with the atmospheric pressure plasma generating part, so that the oxygen-containing gas is ionized in the atmospheric pressure plasma generating part and then enters the fuel cell reaction part for electrocatalytic reaction to produce hydrogen peroxide. Since the activated oxygen plasma is more easily protonated and the OO bond is more easily dissociated, it is more easily catalytically reduced, thereby effectively improving the catalytic efficiency of electrocatalytic reduction of oxygen-containing gas to produce hydrogen peroxide and the yield of hydrogen peroxide.

[0031] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0033] Figure 1 A schematic structural diagram of a specific embodiment of the electrocatalytic reaction system provided in the present disclosure.

[0034] Description of Reference Numerals

[0035] A—normal pressure plasma generating part, 1—central electrode, 2—shell, 3—gas inlet, 4—insulating layer, 5—outer electrode,

[0036] B—fuel cell reaction part, 6—cathode catalyst layer, 7—cathode gas diffusion layer, 8—proton exchange membrane, 9—anode gas diffusion layer, 10—anode catalyst layer, 11—through hole, 12—cathode chamber, 13—anode chamber. DETAILED DESCRIPTION

[0037] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0038] In a first aspect, the present disclosure provides an electrocatalytic reaction system, referring to Figure 1 The system comprises a normal-pressure plasma generating part A and a fuel cell reaction part B, wherein the normal-pressure plasma generating part A is used to provide normal-pressure plasma to the fuel cell reaction part B; wherein the fuel cell reaction part B comprises a cathode membrane electrode assembly and an anode membrane electrode assembly, wherein the cathode membrane electrode assembly has a through hole 11; the normal-pressure plasma generating part A comprises a cylindrical central electrode 1 and a tubular outer electrode 5, wherein an insulating layer 4 is provided between the central electrode 1 and the outer electrode 5, wherein a cavity for accommodating a plasma working gas is formed between the central electrode 1 and the insulating layer 4, wherein the insulating layer 4 extends into the through hole 11.

[0039] According to the present disclosure, atmospheric pressure plasma can be generated in the atmospheric pressure plasma generating part A, wherein atmospheric pressure plasma refers to plasma formed by ionization of a plasma working gas under normal pressure (i.e., atmospheric pressure). In the present disclosure, an oxygen-containing gas is used as a plasma working gas, and atmospheric pressure oxygen plasma can be obtained by ionization (i.e., ionization). Oxygen plasma, as a highly active species, has an extraordinary molecular activation ability, and catalytic reduction of it to prepare hydrogen peroxide is conducive to obtaining a higher catalytic efficiency of hydrogen peroxide and a higher yield of hydrogen peroxide.

[0040] The system further includes a power supply, which is connected between the central electrode 1 and the outer electrode 5 and is used to provide alternating current (e.g., an alternating voltage of 1 to 30 kV and a frequency of 0.5 to 20 kHz) to the central electrode 1 and the outer electrode 5, and the outer electrode 5 is partially grounded. Thus, under the action of the electric field, the plasma working gas is ionized to obtain plasma.

[0041] In one embodiment, the central electrode 1 is coaxially arranged with the outer electrode 5, that is, the central electrode 1 is arranged at the axial center position of the outer electrode 5. Further, the atmospheric pressure plasma generating part A further comprises a housing 2 for fixing the central electrode 1 and the outer electrode 5; specifically, the housing 2 may be provided with a mounting hole, the central electrode 1 is fixedly mounted in the mounting hole and the end thereof protrudes from the mounting hole, so as to facilitate connection of a power source.

[0042] The atmospheric pressure plasma generating part A may be arranged above the fuel cell reaction part B. At this time, the central electrode 1 extends in the vertical direction. The central electrode 1 may have a certain distance from the cathode membrane electrode assembly. Specifically, in the extending direction of the central electrode 1, the distance between the end (i.e., the lower end) of the central electrode 1 close to the cathode membrane electrode assembly and the cathode membrane electrode assembly may be 0.5 to 5 cm. Both ends (upper and lower ends) of the insulating layer 4 extend beyond the end of the outer electrode 5, and a gas inlet 3 is provided at the end (i.e., the upper end) of the insulating layer 4 away from the cathode membrane electrode assembly, and the gas inlet 3 is used to introduce plasma working gas. The lower end of the insulating layer 4 extends into the through hole 11, and the distance from the insulating layer 4 to the end of the outer electrode 5 may be 1 to 10 mm.

[0043] The inner diameter of the through hole 11 matches the outer diameter of the insulating layer 4. The insulating layer 4 and the through hole 11 can be fixed and sealed by a curing agent, and the curing agent can be at least one selected from epoxy resin, acrylic resin and methyl polyurethane. Further, the contact portion of the external electrode 5 with the cathode membrane electrode assembly can also be fixed and sealed by the above curing agent.

[0044] The diameter of the central electrode 1 may be 1 to 5 mm; the inner diameter of the outer electrode 5 may be 10 to 20 mm, and the difference between the outer diameter and the inner diameter of the outer electrode may be 2 to 5 mm; the thickness of the insulating layer may be 3 to 5 mm.

[0045] The central electrode 1 may be made of a high temperature resistant and highly conductive metal, for example, the central electrode 1 may be made of at least one of stainless steel, tungsten, thorium oxide-tungsten alloy, and cerium oxide-tungsten alloy. The outer electrode 5 may be made of common electrode materials in the art, for example, the outer electrode 5 may be made of at least one of copper, zirconium, and silver. The insulating layer may be made of at least one of glass, ceramic, and resin.

[0046] The fuel cell reaction part B in the present disclosure adopts a membrane electrode reaction system, which can largely solve the problems of poor oxygen mass transfer, low current efficiency, and low H2O2 production rate. The effective active area of ​​the cathode membrane electrode assembly and the anode membrane electrode assembly can be 1 to 5 cm2 , where the effective active area refers to the area exposed to the electrolyte.

[0047] In one embodiment, the cathode membrane electrode assembly includes a cathode catalyst layer 6, a cathode chamber 12 and a cathode gas diffusion layer 7 stacked in sequence, the through hole 11 can be opened through the cathode catalyst layer 6, and the external electrode 5 abuts against the surface of the cathode catalyst layer 6.

[0048] The anode membrane electrode assembly includes an anode catalyst layer 10, an anode chamber 13 and an anode gas diffusion layer 9 which are stacked in sequence. The anode gas diffusion layer 9 is close to the cathode gas diffusion layer 7. A proton exchange membrane 8 is provided between the cathode gas diffusion layer 7 and the anode gas diffusion layer 9.

[0049] Furthermore, the cathode catalyst layer may contain a cathode catalyst and a perfluorosulfonic acid resin; wherein the weight ratio of the cathode catalyst to the perfluorosulfonic acid resin may be (3 to 15): 1; the cathode catalyst is preferably a nitrogen-doped carbon material, and the nitrogen content of the carbon material may be 0.01 to 5% by weight based on the total weight of the carbon material. The nitrogen-doped carbon material may be commercially available or synthesized in a laboratory. In one embodiment, the preparation step of the nitrogen-doped carbon material comprises: calcining carbon particles (the particle size may be 300 to 1000 μm) in an NH3 atmosphere. The calcination conditions may include: a temperature of 600 to 900°C and a time of 2 to 4 hours.

[0050] The anode catalyst layer contains an anode catalyst; specifically, the anode catalyst can be at least one selected from platinum, carbon-supported platinum and carbon-supported platinum alloy. When the anode catalyst is carbon-supported platinum and / or carbon-supported platinum alloy, the platinum content of the anode catalyst can be 0.01 to 0.5 mg / cm based on the total weight of the anode catalyst. 2 .

[0051] The cathode chamber 12 and the anode chamber 13 contain electrolytes respectively. The electrolytes may be at least one selected from sulfuric acid solution, potassium hydroxide solution and perchloric acid solution. The concentration of the electrolytes may be 0.05-0.5 mol / L.

[0052] The cathode gas diffusion layer 7 and the anode gas diffusion layer 9 may be independently made of carbon paper and / or carbon cloth.

[0053] The proton exchange membrane 8 may be at least one selected from the group consisting of a Nafion membrane (sulfonated polytetrafluoroethylene proton membrane), a sulfonated polystyrene proton membrane, and a sulfonated polybenzimidazole proton membrane.

[0054] In a second aspect of the present disclosure, a method for electrocatalytically producing hydrogen peroxide using the system described in the first aspect of the present disclosure is provided, the method comprising the following steps S1-S2:

[0055] S1, allowing a plasma working gas to enter the atmospheric pressure plasma generating part for ionization to obtain oxygen plasma; wherein the plasma working gas is an oxygen-containing gas;

[0056] S2, allowing the oxygen plasma to enter the fuel cell reaction part through the through hole to perform an electrocatalytic reaction to obtain hydrogen peroxide.

[0057] In step S1, the oxygen-containing gas may be a mixed gas of oxygen and helium, and specifically, the volume ratio of the oxygen to the helium may be (5-1):1. The oxygen-containing gas may enter the cavity between the central electrode 1 and the insulating layer 4 through the gas inlet 3 and be ionized under the action of the electric field. The flow rate of the oxygen-containing gas may be 1-50 SLM.

[0058] The ionization conditions may include: an AC voltage of 1 to 30 kV and a frequency of 0.5 to 20 kHz.

[0059] In step S2, the oxygen plasma can enter the cathode membrane electrode assembly of the fuel cell reaction part through the through hole under the action of the electric field to continue the electrocatalytic reaction. The conditions of the electrocatalytic reaction may include: a constant voltage of 0.65 to 1.1 V and a time of 1 to 4 hours.

[0060] The electrocatalytic reaction system disclosed in the present invention combines a fuel cell reaction part with a normal-pressure plasma generating part, so that the oxygen-containing gas is ionized in the normal-pressure plasma generating part and then enters the fuel cell reaction part for electrocatalytic reaction to produce hydrogen peroxide. Since the activated oxygen plasma is more easily protonated and the OO bond is more easily dissociated, it is more easily catalytically reduced, thereby effectively improving the catalytic efficiency of electrocatalytic reduction of oxygen-containing gas to produce hydrogen peroxide and the yield of hydrogen peroxide.

[0061] The present disclosure is further illustrated by the following examples.

[0062] In the following examples, unless otherwise specified, all reagents used are commercially available chemical reagents and there are no particular limitations thereto.

[0063] Example 1

[0064] use Figure 1The electrocatalytic reaction system shown in the figure, wherein the atmospheric pressure plasma generating part A comprises a coaxial central electrode 1 and an outer electrode 5, with an insulating layer 4 arranged therebetween. The material of the central electrode is metal tungsten with an outer diameter of 4.5 mm; the outer electrode is a metal copper tube with an inner diameter of 15 mm and an outer diameter of 18 mm, and the insulating layer is a glass tube with an inner diameter of 12 mm, an outer diameter of 15 mm, and a thickness of 3 mm. The outer electrode part is connected to the ground. The fuel cell reaction part B comprises a cathode membrane electrode assembly and an anode membrane electrode assembly, wherein the cathode membrane electrode assembly comprises a cathode catalyst layer 6, a cathode chamber 12, and a cathode gas diffusion layer 7 stacked in sequence, and the anode membrane electrode assembly comprises an anode gas diffusion layer 9, an anode chamber 13, and an anode catalyst layer 10 stacked in sequence, and a proton exchange membrane 8 is arranged between the cathode gas diffusion layer 7 and the anode gas diffusion layer 9. The cathode chamber 12 and the anode chamber 13 contain sulfuric acid solution with a concentration of 0.5 mol / L respectively. The proton exchange membrane is a Nafion membrane, and the cathode gas diffusion layer and the anode gas diffusion layer are carbon cloth respectively. The anode catalyst is commercially available platinum nanoparticles (500nm). The cathode catalyst layer contains a cathode catalyst and a perfluorosulfonic acid resin, wherein the cathode catalyst is nitrogen-doped activated carbon particles, and the synthesis method thereof is as follows: 5g of activated carbon particles (900μm) are calcined at 850°C for 3.5h under an NH3 atmosphere to obtain nitrogen-doped activated carbon particles, wherein the nitrogen content is 5% by weight, and the weight ratio of the cathode catalyst to the perfluorosulfonic acid resin is 3.5. The cathode catalyst layer 6, cathode chamber 12, cathode gas diffusion layer 7, anode gas diffusion layer 9, anode chamber 13, and anode catalyst layer 10 are pressed together by hot pressing, the hot pressing temperature is 150°C, the hot pressing time is 120s, and the hot pressing pressure is 1.8Mpa. The effective active areas of the cathode membrane electrode assembly and the anode membrane electrode assembly are 4cm each. 2 The cathode catalyst layer 6 is provided with a through hole 11 with a diameter of 15 mm. The glass tube of the atmospheric pressure plasma generating part A is inserted into the through hole 11. The outer electrode 5 is in contact with the surface of the cathode catalyst layer 6. The lower end of the central electrode 1 is spaced 2.5 cm from the cathode catalyst layer 6. The insulating layer 4 is fixed and sealed with the through hole 11 by epoxy resin.

[0065] High-purity oxygen and helium are mixed in a volume ratio of 2:1, enter from the gas inlet 3 at a total flow rate of 2.0 SLM and pass through the glass tube of the atmospheric pressure plasma generating part A, and are ionized at an AC voltage of 10 kV, 20 kHz. The obtained oxygen ions enter the cathode catalyst layer 6 through the through hole 11 under the drive of the electric field, and an electrocatalytic reaction is carried out at a constant voltage of 0.8 V. The reaction time is 2 hours, and the sulfuric acid solutions in the anode chamber and the cathode chamber are circulated at a rate of 20 mL / min respectively.

[0066] By cerium sulfate titration (2Ce 4+ +H2O2→2Ce 3+ +2H ++O2) to measure the H2O2 produced by the electrocatalytic oxygen reduction reaction, and the Ce 4+ The concentration of H2O2 generated was calculated by the concentration of 1.5 wt% HO (absorption peak around 316 nm). The Faraday efficiency, selectivity and yield of H2O2 were calculated according to the following formula. The results are shown in Table 1.

[0067] H2O2 Faraday efficiency (%) = (n×V×C H2O2 ×F) / Q×100%

[0068] H2O2 selectivity (%) = (V × C H2O2 ) / {[(Q-2×V×C H2O2 ×F) / 2×F]×1 / 2+V×

[0069] C H2O2 ]}×100%

[0070] H2O2 yield = (V × C H2O2 ) / (A×t)

[0071] Where n is the number of electrons required to transfer to generate one H2O2 molecule in the reaction (n = 2 in this reaction), V is the volume of the electrolyte circulating in the cathode chamber (in L), C H2O2 is the concentration of H2O2 generated (in mol / L), F is the Faraday constant (F=96485C / mol), Q is the charge of the electrolysis reaction (in C), t is the time of the electrolysis reaction (in min), S is the area of ​​the working electrode (in cm 2 ).

[0072] Comparative Example 1

[0073] Electrocatalytic production of hydrogen peroxide was carried out according to the method of Example 1, except that the atmospheric pressure plasma generating part A was not used, that is, the electrocatalytic reaction was carried out only in the fuel cell reaction part B, oxygen-containing gas was blown into the through hole 11, and the sulfuric acid solution in the anode chamber and the cathode chamber was circulated at a speed of 20 mL / min. Other conditions remained unchanged. The results are shown in Table 1.

[0074] Table 1

[0075] Catalytic effect Example 1 Comparative Example 1 <![CDATA[H2O2 Faraday efficiency / %]]> 90.8 66.4 <![CDATA[H2O2 selectivity / %]]> 95.0 79.5 <![CDATA[H2O2 production rate / μmol·min -1 ·cm -2 > 15.8 9.2

[0076] As can be seen from Table 1, the electrocatalytic production of hydrogen peroxide using the electrocatalytic reaction system disclosed in the present invention can significantly improve the H2O2 Faradaic efficiency, H2O2 selectivity and H2O2 yield.

[0077] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0079] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. An electrocatalytic reaction system, characterized in that: The system comprises a fuel cell reaction part and a normal-pressure plasma generating part for providing normal-pressure plasma to the fuel cell reaction part; wherein the fuel cell reaction part comprises a cathode membrane electrode assembly and an anode membrane electrode assembly, and the cathode membrane electrode assembly has a through hole; the normal-pressure plasma generating part comprises a cylindrical central electrode and a tubular outer electrode, an insulating layer is provided between the central electrode and the outer electrode, a cavity for accommodating a plasma working gas is formed between the central electrode and the insulating layer, and the insulating layer extends into the through hole.

2. The system according to claim 1, wherein: The central electrode is coaxially arranged with the outer electrode; The diameter of the central electrode is 1 to 5 mm; The inner diameter of the outer electrode is 10 to 20 mm, and the difference between the outer diameter and the inner diameter of the outer electrode is 2 to 5 mm; The thickness of the insulating layer is 3-5 mm.

3. The system according to claim 1, wherein: Both ends of the insulating layer extend beyond the end of the outer electrode, and a gas inlet is provided at one end of the insulating layer away from the cathode membrane electrode assembly; In the extension direction of the central electrode, the spacing distance between one end of the central electrode close to the cathode membrane electrode assembly and the cathode membrane electrode assembly is 0.5 to 5 cm.

4. The system according to claim 1, wherein: The material of the center electrode is at least one of stainless steel, tungsten, thorium oxide-tungsten and cerium oxide-tungsten; The material of the outer electrode is at least one of copper, zirconium and silver; The insulating layer is made of at least one of glass, ceramic and resin.

5. The system according to claim 1, wherein: The cathode membrane electrode assembly comprises a cathode catalyst layer, a cathode chamber and a cathode gas diffusion layer which are stacked in sequence, the through hole is opened in the cathode catalyst layer, and the external electrode abuts against the surface of the cathode catalyst layer; The anode membrane electrode assembly comprises an anode catalyst layer, an anode chamber and an anode gas diffusion layer which are stacked in sequence. The anode gas diffusion layer is close to the cathode gas diffusion layer. A proton exchange membrane is arranged between the cathode gas diffusion layer and the anode gas diffusion layer.

6. The system according to claim 5, wherein: The cathode catalyst layer contains a cathode catalyst and a perfluorosulfonic acid resin; wherein the weight ratio of the cathode catalyst to the perfluorosulfonic acid resin is (3-15):1; the cathode catalyst is a nitrogen-doped carbon material, and the nitrogen content of the carbon material is 0.01-5 weight % based on the total weight of the carbon material; The anode catalyst layer contains an anode catalyst; the anode catalyst is at least one selected from platinum, carbon-supported platinum and carbon-supported platinum alloy; The cathode chamber and the anode chamber contain electrolytes respectively, and the electrolyte is at least one selected from sulfuric acid solution, potassium hydroxide solution and perchloric acid solution; The cathode gas diffusion layer and the anode gas diffusion layer are each independently carbon paper and / or carbon cloth; The proton exchange membrane is at least one selected from Nafion membrane, sulfonated polystyrene proton membrane and sulfonated polybenzimidazole proton membrane.

7. The system according to claim 1, wherein: The system also includes a power source connected between the central electrode and the outer electrode, and the outer electrode portion is grounded.

8. The system according to claim 1, wherein: The insulating layer and the through hole are fixed and sealed by a curing agent, and the curing agent is at least one selected from epoxy resin, acrylic resin and polyurethane.

9. A method for electrocatalytically producing hydrogen peroxide using the system according to any one of claims 1 to 8, characterized in that: The method includes: Allowing a plasma working gas to enter the atmospheric pressure plasma generating part for ionization to obtain oxygen plasma; wherein the plasma working gas is an oxygen-containing gas; The oxygen plasma is allowed to enter the fuel cell reaction part through the through hole to perform an electrocatalytic reaction to obtain hydrogen peroxide.

10. The method according to claim 9, wherein: The oxygen-containing gas is a mixed gas of oxygen and helium, wherein the volume ratio of the oxygen to the helium is (5-1):1; The flow rate of the oxygen-containing gas is 1 to 50 SLM; The ionization conditions include: AC voltage of 1 to 30 kV and frequency of 0.5 to 20 kHz; The conditions of the electrocatalytic reaction include: a constant voltage of 0.65 to 1.1 V and a time of 1 to 4 hours.

Images