Electrolytic cell for electrocatalytic synthesis of hydrogen peroxide in acidic system and method for synthesis of hydrogen peroxide

Abstract

The present application relates to the technical field of electrochemical synthesis of hydrogen peroxide, and discloses an electrolytic tank for electrocatalytic synthesis of hydrogen peroxide in an acidic system and a hydrogen peroxide synthesis method. The electrolytic tank comprises: a cathode chamber, a gas diffusion electrode is arranged in the cathode chamber, the gas diffusion electrode comprises a gas diffusion layer and a catalyst layer loaded on the gas diffusion layer, and the catalyst layer comprises a carbon-based catalyst for a two-electron oxygen reduction reaction; an anode chamber, an anode electrode is arranged in the anode chamber; a cation exchange membrane, which is arranged between the cathode chamber and the anode chamber and is used for separating the cathode chamber and the anode chamber and conducting protons; and a current collector, which is electrically connected with the cathode chamber and the anode chamber to realize electron conduction. The electrolytic tank is configured to operate under the condition of a pure acidic electrolyte without alkali metal cations, and the acidic electrolyte is a sulfuric acid solution. The present application realizes electrochemical synthesis of hydrogen peroxide with high selectivity, high concentration and high purity under an ampere-level current density.

Description

Technical Field

[0001] This invention relates to the field of electrochemical synthesis of hydrogen peroxide, and more particularly to an electrolyzer and a method for the electrocatalytic synthesis of hydrogen peroxide in an acidic system. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important green oxidant widely used in chemical synthesis, environmental protection, medical and health applications, and paper bleaching. Currently, the mainstream industrial method for preparing hydrogen peroxide is the anthraquinone process. This method involves multiple steps of hydrogenation and oxidation reactions of organic compounds, resulting in a complex process flow and large equipment requirements, making it unsuitable for portable on-site preparation. Furthermore, the anthraquinone process inevitably involves side reactions during production, generating pollution, and the resulting hydrogen peroxide concentration is approximately 70 wt%, which usually requires dilution in practical applications, increasing the safety risks (such as the risk of explosion) and cost associated with storing and transporting high-concentration hydrogen peroxide. An alternative method is the direct mixing of hydrogen and oxygen, but this method carries the risk of explosion and typically requires an inert gas as a diluent, further increasing production costs.

[0003] To overcome the shortcomings of the above technologies, the electrochemical two-electron oxygen reduction reaction (2e... - ORR (Organic Hydrogen Peroxide) is considered a promising alternative technology. This method can utilize renewable electrical energy to directly synthesize hydrogen peroxide from water and oxygen, thus avoiding the use of toxic reagents and simplifying the process. Studies have shown that acidic systems exhibit higher hydrogen peroxide stability in different electrolyte systems and demonstrate good compatibility with acid-resistant industrial materials (such as polytetrafluoroethylene, fluorinated ethylene propylene, and Nafion membranes), making large-scale application feasible. In contrast, hydrogen peroxide stability is poor in alkaline and neutral systems. However, under purely acidic conditions without alkali metal cations, the stability of existing catalysts is limited. Some metal cation catalysts readily undergo side reactions with reactive oxygen species or hydroxyl radicals generated by Fenton-type reactions, leading to carbon support corrosion and electrode degradation. Therefore, at high current densities (>600 mA cm⁻¹), the stability of existing catalysts is limited. -2 Achieving high selectivity (Faraday efficiency > 80%) in hydrogen peroxide production remains a challenge.

[0004] To address this issue, metal-free carbon-based materials, especially commercially available carbon black, have gradually gained attention due to their chemical inertness, high conductivity, low cost, and excellent resistance to oxidative degradation. Unlike transition metal catalysts, carbon-based materials do not trigger the Fenton reaction and are more suitable for long-term operation under acidic conditions. However, current research on their application in strongly acidic environments without alkali metal cations remains insufficient.

[0005] Regarding reactors, existing technologies for producing hydrogen peroxide via the two-electron oxygen reduction reaction typically employ flow cell devices, but their reaction area is relatively small, usually 1 cm². 2 or 4 cm 2 This results in limited concentration and yield of hydrogen peroxide produced by electrosynthesis. Furthermore, the prepared hydrogen peroxide is mixed with the electrolyte (acid or alkali), requiring further separation and purification in practical applications, increasing subsequent processing costs.

[0006] While solid-state electrolyzers can produce high-purity hydrogen peroxide (the product is mixed with deionized water, without electrolyte), existing solid-state electrolyzers contain both anion exchange membranes and cation exchange membranes. In the two-electron oxygen reduction electrosynthesis of hydrogen peroxide, the anion exchange membrane is relatively fragile, susceptible to hydrogen peroxide corrosion, and expensive, typically for single use, significantly increasing the cost of hydrogen peroxide electrosynthesis. Furthermore, the simultaneous use of anion exchange and cation exchange membranes usually corresponds to reaction mechanisms in alkaline electrolyte environments, making them unsuitable for acidic systems.

[0007] Regarding catalyst materials, Co-based and other metallic materials are commonly used in acidic electrolyte systems. However, their industrial application is limited due to problems such as easy leaching of metals at industrial current densities and structural collapse. Currently, the achievable current density is typically around 500 mA cm⁻¹. -2 the following.

[0008] Therefore, how to utilize stable and efficient metal-free carbon-based catalysts in acidic systems, combined with scalable electrolyzer designs, to achieve high-concentration, high-purity hydrogen peroxide electrosynthesis at industrial current densities has become a pressing technological challenge. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention provides an electrolytic cell and a method for the electrocatalytic synthesis of hydrogen peroxide in an acidic system, thereby realizing the electrocatalytic synthesis of high concentration and high purity hydrogen peroxide at industrial current density in an acidic system.

[0010] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: A first aspect of the present invention provides an electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system, comprising: A cathode chamber is provided with a gas diffusion electrode, the gas diffusion electrode comprising a gas diffusion layer and a catalyst layer supported on the gas diffusion layer, the catalyst layer comprising a carbon-based catalyst for a two-electron oxygen reduction reaction; An anode chamber, wherein an anode electrode is provided; A cation exchange membrane, located between the cathode chamber and the anode chamber, serves to separate the cathode chamber and the anode chamber and to conduct protons; The current collector is electrically connected to the cathode chamber and the anode chamber to enable electron conduction; The electrolytic cell is configured to operate under conditions of a pure acidic electrolyte free of alkali metal cations, wherein the acidic electrolyte is a sulfuric acid solution.

[0011] Optionally, the electrolytic cell is a flow electrolytic cell, the cathode chamber further includes a cathode flow chamber, and the anode chamber further includes an anode flow chamber. The cathode flow chamber and the anode flow chamber are respectively used to supply acidic cathode electrolyte and acidic anode electrolyte.

[0012] Optionally, the electrolyzer is a solid-state electrolyzer and further includes a solid electrolyte chamber located between the cation exchange membrane and the cathode chamber. The solid electrolyte chamber contains a porous solid electrolyte for conducting ions and accommodating the generated hydrogen peroxide.

[0013] Optionally, the solid electrolyte chamber is provided with an inlet and an outlet. The inlet is used to introduce deionized water to carry out the generated hydrogen peroxide, or to utilize the diffusion of the anolyte and carry out the generated hydrogen peroxide by introducing air.

[0014] Optionally, the carbon-based catalyst is a commercial carbon black, such as ECP600JD, EC300J, XC-72, acetylene black, Super P Li, BP2000, XC-72R, EC600JD, KS-6, Super C-45, etc.; preferably, it is a carbon black having a C=O carbonyl functional group and a specific surface area less than or equal to that of ECP600JD, and most preferably, it is ECP600JD.

[0015] Optionally, the anode electrode is a titanium mesh or carbon paper electrode loaded with iridium dioxide; the cation exchange membrane is a perfluorosulfonic acid membrane; and no anion exchange membrane is provided in the electrolytic cell.

[0016] A second aspect of the present invention provides a method for synthesizing hydrogen peroxide, the method comprising the following steps: Acidic electrolyte is introduced into the anode chamber and the cathode chamber respectively; A voltage is applied to the anode chamber, causing the oxygen evolution reaction to occur at the anode, producing protons and oxygen. The protons produced are then directionally transported to the cathode side through the cation exchange membrane. Oxygen-containing gas is introduced into the gas diffusion electrode of the cathode chamber. The oxygen diffuses through the gas diffusion layer to the catalyst layer. Under the action of the carbon-based catalyst, the oxygen reacts with the protons transferred from the anode chamber through the cation exchange membrane to undergo a two-electron oxygen reduction reaction, generating hydrogen peroxide. Collect the generated hydrogen peroxide.

[0017] Optionally, the acidic electrolyte is a sulfuric acid solution with a concentration of 0.5-10 M.

[0018] Optionally, the method is operated at an ampere-level current with a current density ≥500 mA cm⁻¹. -2 The cathode has a Faraday efficiency of ≥80%, or when using a solid electrolyzer and the solid electrolyte chamber is not circulated with water, the hydrogen peroxide concentration is ≥20 wt%, specifically 20-40 wt%.

[0019] Beneficial effects: This invention discloses an electrolyzer and a method for the electrocatalytic synthesis of hydrogen peroxide in acidic systems. Compared with existing technologies, this invention has the following advantages: First, by setting a gas diffusion electrode containing a carbon-based catalyst in the cathode chamber, a highly efficient and stable two-electron oxygen reduction reaction is achieved in the acidic system, avoiding the leaching and structural collapse problems of metal catalysts in acidic environments, and significantly improving the long-term operational stability of the electrode. Specifically, this invention uses a metal-free carbon-based catalyst (such as commercial carbon black) in the gas diffusion electrode of the cathode chamber. In acidic electrolyte systems, traditional Co-based and other metal catalysts are prone to metal ion leaching and easily undergo side reactions with reactive oxygen species or hydroxyl radicals generated by the Fenton reaction, leading to catalyst structural collapse and carbon support corrosion, thus limiting their application at industrial current densities. Carbon-based materials, on the other hand, are chemically inert, do not trigger the Fenton reaction, and can effectively resist the erosion of oxidizing free radicals. More importantly, this invention experimentally demonstrates that carbon-based catalysts with C=O carbonyl functional groups (such as ECP600JD) can optimize the adsorption-desorption balance of the two-electron oxygen reduction reaction intermediate, thereby improving the selectivity of the reaction. Based on this material design, this invention can achieve long-term structural stability of the catalyst layer in harsh environments with strong acidity and no alkali metal cations, avoiding the performance degradation problem of traditional metal catalysts. Second, through the synergistic structural design of the gas diffusion layer and the catalyst layer of the gas diffusion electrode, combined with the proton conduction effect of the cation exchange membrane, efficient oxygen mass transfer and proton supply at ampere-level current densities are achieved, solving the technical problem of limited reactant mass transfer at high current densities. The gas diffusion electrode of this invention includes a gas diffusion layer and a catalyst layer. The gas diffusion layer is composed of carbon fibers and a microporous layer: the carbon fiber layer provides mechanical support and forms gas transport channels, ensuring that oxygen can diffuse efficiently to the catalyst layer; the microporous layer further optimizes mass transfer and hydrophobic properties, preventing the electrolyte from flooding the gas channels. The catalyst layer supports a carbon-based catalyst, forming a gas-liquid-solid three-phase reaction interface. Simultaneously, the cation exchange membrane separates the cathode chamber from the anode chamber and selectively conducts protons (H+) generated at the anode. + The oxygen evolution reaction (2H₂O → O₂ + 4H₂O) occurs at the anode under acidic conditions. + +4e -The protons generated migrate directionally through the cation exchange membrane to the cathode, where they undergo a two-electron oxygen reduction reaction (O2 + 2H+) on the surface of the carbon-based catalyst with oxygen diffused into the catalyst layer. + +2e - → H2O2). This electrode structure, in synergy with the ion-exchange membrane, ensures high current density (>500 mA cm⁻¹). -2 The oxygen mass transfer and proton supply can be dynamically matched, avoiding a decrease in selectivity or an aggravation of side reactions due to insufficient reactant supply, thus supporting the stable operation of ampere-level currents. Third, by configuring the entire electrolyzer to operate under acidic electrolyte conditions, utilizing only a cation exchange membrane and eliminating the use of anion exchange membranes found in traditional solid-state electrolyzers, the system structure is simplified, costs are reduced, and the stability and purity of hydrogen peroxide products are improved. This invention explicitly limits the operation of the electrolyzer to acidic electrolyte conditions, which naturally matches the proton conduction characteristics of the cation exchange membrane. Protons generated at the anode can be directly transferred through the cation exchange membrane to the cathode to participate in the two-electron oxygen reduction reaction, without relying on anion conduction, thus allowing the removal of expensive and hydrogen peroxide-sensitive anion exchange membranes in the design of solid-state electrolyzers. This improvement brings multiple benefits: Firstly, removing the anion exchange membrane significantly reduces the cost of the electrolyzer and avoids performance degradation or single-use issues caused by membrane corrosion, greatly improving the long-term operational stability of the system. Secondly, the acidic environment itself is conducive to the stable existence of hydrogen peroxide. Compared with alkaline and neutral environments, hydrogen peroxide decomposes at a lower rate under acidic conditions, thus maintaining a high concentration and yield of the product at the reaction interface and during collection. When using a solid-state electrolyzer structure without anion exchange membranes, high-purity hydrogen peroxide mixed with deionized water can be directly collected in the solid electrolyte chamber without the need for subsequent electrolyte separation, further reducing purification costs.

[0020] In summary, this invention, through the design of the structural combination of the cathode chamber, anode chamber, and ion exchange membrane, and in conjunction with appropriate operating conditions, enables the electrochemical synthesis of hydrogen peroxide. Compared with existing technologies, this invention offers improvements in product selectivity, product concentration, product purity, system stability, and the scale-up of the reaction apparatus, thus possessing certain practical value. Attached Figure Description

[0021] Figure 1 A schematic diagram of the synthesis of ampere-level high-concentration H2O2 using a flowing electrolytic cell.

[0022] Figure 2 To test the 2e-electrode configuration on an ECP600JD catalyst in a flow electrolyzer system using 1 M sulfuric acid (pH=0) as the electrolyte. - IV curve of ORR.

[0023] Figure 3 The concentration and volume of hydrogen peroxide directly flowing out under an ampere-level current.

[0024] Figure 4 This is a schematic diagram of the synthesis of high-purity H2O2 using a solid electrolyte electrolytic cell.

[0025] Figure 5 SEM and TEM images of carbon black catalysts with different surface oxygen contents.

[0026] Figure 6 BET specific surface area analysis for different carbon blacks.

[0027] in, Figure 1 1 is titanium plate; 2 is carbon black; 3 is iridium dioxide; 4 is cathode flow chamber; 5 is anode flow chamber; 6 is cation exchange membrane; 7 is gas diffusion layer; 8 is catalyst layer; 9 is gas diffusion electrode.

[0028] Figure 4 1 is a titanium plate; 2 is an ECP600JD; 6 is a cation exchange membrane; 7 is a gas diffusion layer; 8 is a catalyst layer; 9 is a gas diffusion electrode; 10 is a solid electrolyte chamber; 11 is iridium dioxide. Detailed Implementation

[0029] This invention provides an electrolyzer and a method for the electrocatalytic synthesis of hydrogen peroxide in an acidic system. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] The core of this invention lies in the screening of metal-free carbon-based catalysts and the development of large-area flow electrolyzers (1-200 cm²). 2 The design of the electrolytic cell and the improvement of the anion-free membrane solid electrolyzer enable the high-concentration, high-purity superoxide electrocatalytic synthesis under acidic system with ampere-level current density. The following details the construction, operation and performance verification of the two electrolyzers, as well as the catalyst screening.

[0031] Example 1: Construction of a large-area flow electrolyzer and synthesis of high-concentration H2O2 1. Electrolytic cell structure This invention provides a flow electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system, the structure of which is as follows: Figure 1 As shown, it includes: A cathode chamber is provided, and a gas diffusion electrode 9 is disposed within the cathode chamber. The gas diffusion electrode 9 comprises a gas diffusion layer 7 and a catalyst layer 8 supported on the gas diffusion layer. The gas diffusion layer 7 consists of a carbon fiber layer and a microporous layer. The carbon fiber layer provides mechanical support and gas transport channels, while the microporous layer optimizes mass transfer and hydrophobic properties, and is located between the titanium plate 1 and the catalyst layer 8. The catalyst layer 8 contains a carbon-based catalyst for the two-electron oxygen reduction reaction. In this embodiment, commercial carbon black ECP600JD is used, coated on the surface of the gas diffusion layer 7, and located between the gas diffusion layer 7 and the cathode flow chamber 4. The cathode flow chamber 4 serves as a flow channel for the cathode electrolyte (1 M H2SO4).

[0032] The anode chamber contains an anode electrode 3. The anode electrode 3 is a commercial catalyst, iridium dioxide (IrO2), supported on carbon paper. The anode flow chamber 5 is a flow channel for the anolyte (1 M H2SO4).

[0033] A cation exchange membrane 6, located between the cathode chamber and the anode chamber, separates the cathode chamber and the anode chamber and conducts protons. In this embodiment, a perfluorosulfonic acid membrane, Nafion 117, is used.

[0034] Titanium plate 1, acting as a current collector, is located outside the cathode and anode chambers, supporting electron conduction.

[0035] The electrode area of ​​the cathode and anode chambers of the flowing electrolyzer is 30.25 cm². 2 It is much larger than the 1-4 cm of traditional flow cells. 2 .

[0036] 2. Working principle Under acidic conditions, the oxygen evolution reaction occurs at the anode: 2H₂O → O₂ + 4H₂O + +4e - The protons produced (H) + The oxygen is directionally transported to the cathode chamber through the cation exchange membrane 6. Oxygen or air is introduced into the gas diffusion electrode 9 in the cathode chamber. The oxygen diffuses through the gas diffusion layer 7 to the catalyst layer 8, where it undergoes a two-electron oxygen reduction reaction with protons on the surface of the ECP600JD catalyst: O2 + 2H+ + +2e - →H2O2. The generated H2O2 is carried away by the cathode electrolyte and collected from the outlet of cathode flow chamber 4. By adjusting the flow rates of the electrolyte in cathode flow chamber 4 and anode flow chamber 5, the concentration of H2O2 generated under ampere-level current and the Faraday efficiency can be balanced, preventing excessive concentration of H2O2 generated at the interface or excessive residence time leading to further oxidation or decomposition.

[0037] 3. Electrochemical performance testing A two-electrode system is employed. In some embodiments, both the cathode electrolyte and the anolyte can be acidic electrolytes, such as sulfuric acid solution; the concentration of the sulfuric acid solution can be approximately 1 M; the reaction gas can be an oxygen-containing gas, such as oxygen, and its flow rate can be on the order of several hundred sccm, for example, approximately 200 sccm. Test results are as follows... Figure 2 As shown.

[0038] Figure 2 The IV curve of the device is shown. The results indicate that under relatively large operating current conditions, the battery voltage can be maintained within a reasonable range, such as several volts to more than ten volts, indicating that the system has good conductivity and electrochemical reactivity.

[0039] Figure 3 The results show that H2O2 products were continuously collected under ampere-level current conditions. The results demonstrate that the device can continuously output a certain volume of H2O2 solution at higher operating currents, and the resulting product maintains a relatively stable concentration level, thus verifying that this large-area flow electrolyzer has the capability to continuously produce high-concentration H2O2.

[0040] Example 2: Construction of an anion exchange membrane-free solid-state electrolyzer and synthesis of high-purity H2O2 1. Electrolytic cell structure This embodiment provides an anion-free membrane-free solid electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system, the structure of which is as follows: Figure 4 As shown, it includes: A cathode chamber is provided, and a gas diffusion electrode 9 is disposed therein. The gas diffusion electrode 9 includes a gas diffusion layer 7 and a catalyst layer 8 supported on the gas diffusion layer. The gas diffusion layer 7 is composed of a carbon fiber layer and a microporous layer and is located between the titanium plate 1 and the catalyst layer 8. The catalyst layer 8 contains a carbon-based catalyst for the two-electron oxygen reduction reaction; in this embodiment, commercial carbon black ECP600JD is used, and it is located between the gas diffusion layer 7 and the solid electrolyte layer 10.

[0041] An anode chamber is provided, wherein an anode electrode 11 is provided. The anode electrode 11 is a titanium mesh loaded with commercial iridium dioxide (IrO2).

[0042] A cation exchange membrane 6, located between the anode chamber and the solid electrolyte chamber, separates the anode chamber and the solid electrolyte chamber and conducts protons. In this embodiment, a perfluorosulfonic acid membrane, Nafion 117, is used.

[0043] A solid electrolyte chamber 10 is located between the cation exchange membrane 6 and the cathode chamber. The solid electrolyte chamber 10 is filled with a porous solid electrolyte, which is composed of a styrene-divinylbenzene copolymer with sulfonic acid functional groups (for cation conduction) and serves as an electrical conductor. The solid electrolyte chamber 10 is separated from the anode chamber by the cation exchange membrane 6 and from the cathode chamber by the cathode gas diffusion electrode 9. The solid electrolyte chamber 10 has an inlet and an outlet; the inlet is used to introduce deionized water or air.

[0044] Titanium plate 1, as the cathode current collector, is located outside the cathode chamber.

[0045] 2. Working principle Under acidic conditions, the oxygen evolution reaction occurs at the anode: 2H₂O → O₂ + 4H₂O + + 4e - The protons produced (H) + The protons enter the solid electrolyte chamber 10 through the cation exchange membrane 6 and are conducted within the porous solid electrolyte. Oxygen or air is introduced into the gas diffusion electrode 9 of the cathode chamber. The oxygen diffuses through the gas diffusion layer 7 to the catalyst layer 8, where a two-electron oxygen reduction reaction occurs on the surface of the ECP600JD catalyst. The protons consumed in the cathode reaction originate from the H+ conducted in the solid electrolyte chamber 10. + The generated H2O2 enters the porous solid electrolyte in the solid electrolyte chamber 10.

[0046] Deionized water can be introduced into the inlet of the solid electrolyte chamber 10. The water flows through the porous solid electrolyte, carrying away the generated H2O2 to obtain an aqueous H2O2 solution. Alternatively, instead of introducing deionized water into the inlet of the solid electrolyte chamber 10, the anolyte (1 M H2SO4) can diffuse into the solid electrolyte chamber 10 through the cation exchange membrane 6. Then, by introducing air into the solid electrolyte chamber 10, the high-concentration H2O2 liquid product is blown out, achieving the preparation of ultra-high concentration H2O2.

[0047] 3. Electrochemical performance testing In some embodiments of a solid-state electrolyzer with a two-electrode system, an oxygen-containing gas, such as oxygen, can be introduced to the cathode side; its flow rate can be on the order of several hundred sccm, for example, about 200 sccm. An acidic electrolyte, such as a sulfuric acid solution, with a concentration of about 1 M can be used on the anode side.

[0048] Example 3 Screening and Characterization of Carbon-Based Catalysts To investigate the performance differences of different commercial carbon black catalysts in the two-electron oxygen reduction reaction in an acidic system, this example systematically characterized the morphology, structure and electrochemical performance of four commercial carbon blacks (including ECP600JD, EC300J, XC-72 and acetylene black).

[0049] 1. Morphological and structural characterization Figure 5 The images show SEM and TEM images of four carbon black catalysts. The results indicate that ECP600JD has a grape-like structure with more hollow spheres, while the other control samples are mostly solid spheres. This hollow structure is advantageous in providing more reactive sites.

[0050] Figure 6 For BET specific surface area analysis. The ECP600JD has the largest specific surface area, which is beneficial for oxygen transport and mass transfer processes.

[0051] 2. Structure-function relationship analysis Based on the electrochemical test results (Examples 1 and 2), ECP600JD exhibits the best two-electron oxygen reduction performance. Its excellent performance is attributed to: (1) high specific surface area: providing abundant reactive sites, which is beneficial for oxygen adsorption and mass transfer; (2) abundant C=O carbonyl functional groups: theoretical calculations and literature [2] show that C=O functional groups are the active sites for two-electron oxygen reduction reactions, which can optimize the adsorption free energy of the reaction intermediate OOH, realize the adsorption-desorption balance of OOH, and thus improve the reaction selectivity and activity; (3) chemical inertness: as a metal-free carbon-based material, it avoids catalyst degradation caused by Fenton reaction and ensures long-term stability in acidic systems.

[0052] Therefore, ECP600JD, as the preferred carbon-based catalyst of this invention, can achieve efficient and stable two-electron oxygen reduction synthesis of hydrogen peroxide in an acidic system.

[0053] Example 4: Comparison of different carbon-based catalysts In the flow electrolyzer of Example 1, ECP600JD, EC300J, XC-72, and acetylene black were used as cathode catalysts, respectively, under the same test conditions (1 M H2SO4, current density 100 mA cm⁻¹). -2 The two-electron oxygen reduction performance was evaluated. The results showed that ECP600JD had the highest Faraday efficiency (82%), followed by EC300J (70%), while XC-72 (52%) and acetylene black (40%) had relatively low efficiency. Combined with the characterization results of Example 3, the positive correlation between the C=O functional group content and the two-electron oxygen reduction performance was confirmed.

[0054] Comparison of Example 1 with a traditional small-area flow cell Using a traditional area of ​​1 cm 2 A flow cell was used with ECP600JD as the catalyst, under the same test conditions (1 MH2SO4, current density 100 mA cm⁻¹). -2The experiment was conducted under these conditions. Results showed that the single-efferentiation H2O2 concentration in the small-area flow cell was low, significantly lower than that observed in Example 1 at 30.25 cm⁻¹. 2 The concentrations obtained in a large-area flow electrolyzer at similar current densities demonstrate that the scaled-up electrode area design of this invention can effectively improve product concentration and production efficiency without exhibiting significant mass transfer limitations or exacerbated side reactions.

[0055] Comparison of Example 2 with a solid-state electrolyzer containing anion exchange membrane A conventional dual-membrane solid-state electrolyzer using anion exchange membranes (such as Sustainion X37-50 GradeRT, Sustainion X-37-50, Sustainion X-37-50 Grade 60, Sustainion E28-50 GradeT, Sustainion X-37-50 GradeFA, Fumasep FAA-3-20, Fumasep FAA-3-50, Fumasep FAA-3-PK-75, Fumasep FAA-3-PK-130, EC-FUMA-PK-130) and cation exchange membranes (Nafion 117, Nafion 212, Nafion 115) with ECP600JD as the cathode catalyst was operated under alkaline conditions. After 10-48 hours of operation, the anion exchange membranes were corroded by hydrogen peroxide, leading to an increase in system internal resistance and a decrease in Faraday efficiency. In Example 2, the anion-free solid-state electrolyzer operated continuously for 120 hours under acidic conditions without exhibiting cation membrane corrosion, maintaining stable performance. This demonstrates that the anion membrane removal design of this invention significantly improves the long-term stability and durability of the system.

[0056] Based on the design concept of Example 1, the electrode area of ​​the flow electrolyzer can be further increased to 100 cm². 2 200cm 2 Or even larger, by optimizing the flow field distribution and flow collection structure, a larger-scale H2O2 production can be achieved. Similarly, the solid-state electrolyzer of Example 2 can also be designed with an increased area to meet the needs of industrial production.

[0057] Besides ECP600JD, other commercial carbon blacks or modified carbon materials (such as graphene oxide, nitrogen-doped carbon materials, etc.) with high specific surface area and abundant C=O functional groups can also be used as cathode catalysts in this invention. For example, by using BP2000 and increasing the C=O functional group content through surface oxidation treatment, its two-electron oxygen reduction performance in acidic systems is significantly improved.

[0058] The acidic electrolyte of this invention is not limited to 1 M H2SO4; other concentrations of sulfuric acid (such as 0.5-10 M H2SO4) can also achieve similar technical effects at appropriate concentrations (such as 0.5 M to 2 M). The key is to maintain the acidic environment of the system to ensure efficient proton conduction and the stability of H2O2.

[0059] In addition to iridium dioxide (IrO2), other materials with good oxygen evolution reaction activity and acid stability can also be used as anode catalysts, such as ruthenium-based oxides (RuO2), platinum-based materials, or non-noble metal oxygen evolution catalysts, as long as they can stably generate protons and conduct them to the cathode.

[0060] In summary, this invention, through a structural combination of a cathode chamber gas diffusion electrode (containing a carbon-based catalyst), an anode chamber, and a cation exchange membrane, and by operating under acidic conditions, achieves the electrochemical synthesis of hydrogen peroxide with high selectivity, high concentration, and high purity at ampere-level current densities. This technical solution overcomes the problems of poor catalyst stability, low reactor yield, and insufficient product purity in existing technologies, and has promising prospects for industrial application.

[0061] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system, characterized in that, include: A cathode chamber is provided with a gas diffusion electrode, the gas diffusion electrode comprising a gas diffusion layer and a catalyst layer supported on the gas diffusion layer, the catalyst layer comprising a carbon-based catalyst for a two-electron oxygen reduction reaction; An anode chamber, wherein an anode electrode is provided; A cation exchange membrane, located between the cathode chamber and the anode chamber, serves to separate the cathode chamber and the anode chamber and to conduct protons; The current collector is electrically connected to the cathode chamber and the anode chamber to enable electron conduction; The electrolytic cell is configured to operate under conditions of a pure acidic electrolyte free of alkali metal cations, wherein the acidic electrolyte is a sulfuric acid solution.

2. The electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system according to claim 1, characterized in that, The electrolytic cell is a flow electrolytic cell. The cathode chamber further includes a cathode flow chamber, and the anode chamber further includes an anode flow chamber. The cathode flow chamber and the anode flow chamber are used to supply acidic cathode electrolyte and acidic anode electrolyte, respectively.

3. The electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system according to claim 1, characterized in that, The electrolyzer is a solid-state electrolyzer and also includes a solid electrolyte chamber located between the cation exchange membrane and the cathode chamber. The solid electrolyte chamber contains a porous solid electrolyte for conducting ions and accommodating the generated hydrogen peroxide.

4. The electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system according to claim 3, characterized in that, The solid electrolyte chamber is provided with an inlet and an outlet. The inlet is used to introduce deionized water to carry out the generated hydrogen peroxide, or to utilize the diffusion of the anolyte and carry out the generated hydrogen peroxide by introducing air.

5. The electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system according to claim 1, characterized in that, The carbon-based catalyst is commercial carbon black.

6. The electrolyzer for the electrocatalytic synthesis of hydrogen peroxide in an acidic system according to claim 1, characterized in that, The anode electrode is a titanium mesh or carbon paper electrode loaded with iridium dioxide; the cation exchange membrane is a perfluorosulfonic acid membrane; and no anion exchange membrane is provided in the electrolytic cell.

7. A method for synthesizing hydrogen peroxide based on the electrolyzer according to any one of claims 1-6, characterized in that, The synthesis method includes the following steps: Acidic electrolyte is introduced into the anode chamber and the cathode chamber respectively; A voltage is applied to the anode chamber, causing the oxygen evolution reaction to occur at the anode, producing protons and oxygen. The protons produced are then directionally transported to the cathode side through the cation exchange membrane. Oxygen-containing gas is introduced into the gas diffusion electrode of the cathode chamber. The oxygen diffuses through the gas diffusion layer to the catalyst layer. Under the action of the carbon-based catalyst, the oxygen reacts with the protons transferred from the anode chamber through the cation exchange membrane to undergo a two-electron oxygen reduction reaction, generating hydrogen peroxide. Collect the generated hydrogen peroxide.

8. The method according to claim 7, characterized in that, The acidic electrolyte is a sulfuric acid solution with a concentration of 0.5-10 M.

9. The method according to claim 7, characterized in that, The method operates at ampere-level currents with a current density ≥500 mA cm⁻¹. -2 The cathode has a Faraday efficiency of ≥80%, or when using a solid electrolyzer and the solid electrolyte chamber is not circulated with water, the hydrogen peroxide concentration is ≥20 wt%.

Images