Catalyst for electrocatalytic synthesis of hydrogen peroxide as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for electrocatalytic synthesis of hydrogen peroxide and a preparation method and application thereof, vegetable oil is used as a raw material, the vegetable oil is ignited under the condition of insufficient oxygen, and black soot formed by combustion is collected as the catalyst. The preparation method disclosed by the invention has the advantages of renewable raw materials, simple preparation process, low cost, environmental friendliness and the like; the prepared catalyst shows excellent catalytic activity, selectivity and stability in a reaction for synthesizing hydrogen peroxide through electro-catalytic oxygen reduction; the invention provides a new thought for green, efficient and large-scale electrosynthesis of hydrogen peroxide.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to a catalyst for the electrocatalytic synthesis of hydrogen peroxide, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important green chemical product, widely used in papermaking, environmental protection, chemical synthesis, and disinfection. Currently, large-scale industrial production of hydrogen peroxide mainly relies on the anthraquinone process. This process consumes a large amount of hydrogen gas, generates a large amount of organic waste liquid, and requires subsequent purification processes to obtain a pure hydrogen peroxide solution. Furthermore, the process involves transportation to its destination, which not only consumes energy but also causes environmental pollution.

[0003] Electrocatalytic two-electron oxygen reduction (OOR) is a promising alternative method that can directly synthesize hydrogen peroxide from oxygen and water under mild conditions, offering advantages such as a clean process, low energy consumption, and distributed production capabilities. The core of this technology lies in developing highly active, selective, and stable electrocatalysts. In recent years, carbon-based materials have been considered the most promising alternative due to their wide availability, low cost, good conductivity, and ease of control. Researchers have developed various doped (e.g., oxygen- and nitrogen-doped) or defect-engineered carbon materials to improve their OOR selectivity. To enhance performance, it is often necessary to artificially introduce oxygen-containing functional groups or defects into carbon materials through methods such as concentrated nitric acid oxidation or plasma treatment. These post-treatment steps typically involve highly corrosive reagents or complex equipment, increasing process complexity and cost, and potentially causing secondary pollution.

[0004] Therefore, developing a carbon catalyst for the two-electron oxygen reduction reaction that uses renewable raw materials, has a simple preparation process (especially avoiding complex post-processing), is low in cost, and has excellent performance is of great practical significance. Summary of the Invention

[0005] This invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a catalyst for the electrocatalytic synthesis of hydrogen peroxide, its preparation method and application.

[0006] This invention is achieved through the following technical solution: A method for preparing a catalyst for the electrocatalytic synthesis of hydrogen peroxide is as follows: using vegetable oil as a raw material, the vegetable oil is ignited under conditions of insufficient oxygen, and the black soot formed by combustion is collected as the catalyst.

[0007] In the above technical solution, the condition of insufficient oxygen is specifically as follows: a metal plate or ceramic plate is suspended above the flame of vegetable oil combustion. The baffle effectively blocks the free diffusion of combustion products and forms a confined combustion microenvironment above the flame zone, thereby significantly reducing the mass transfer rate of oxygen to the combustion reaction core.

[0008] In the above technical solution, the method for collecting the black soot formed by combustion is as follows: a clean, cooled metal plate or ceramic plate is suspended 10cm to 15cm above the flame of vegetable oil combustion, and the black soot formed by vegetable oil combustion is deposited on the metal plate or ceramic plate.

[0009] In the above technical solution, the vegetable oil is at least one of tung oil, flaxseed oil, tallow tree oil, soybean oil, rapeseed oil, sunflower seed oil, sesame oil, or cottonseed oil.

[0010] In the above technical solution, the prepared oxygen-doped graphite carbon material catalyst can be used in the electrocatalytic two-electron oxygen reduction reaction to produce hydrogen peroxide. The preparation method is based on a flow cell reactor or a porous solid-state electrolyte reactor. The reactor uses a conductive substrate loaded with the catalyst prepared by the aforementioned method as the cathode, and the catalyst loading is 0.2 mg / cm³. 2 ~0.8 mg / cm 2 .

[0011] In the above technical solution, the flow cell reactor includes a cathode, an anion exchange membrane and an anode arranged in sequence; the porous solid electrolyte reactor includes a cathode, an anion exchange membrane, a porous solid electrolyte layer, a proton exchange membrane and an anode arranged in sequence.

[0012] In the above technical solutions, when implemented based on a flow cell reactor, The anion exchange membrane is any one of FAA-3-50, FAA-3-PK-75 or FAA-3-PK-130; The electrolyte in the reactor is an alkaline solution. The electrolyte flow rate on the cathode side is 90 mL / h to 150 mL / h, and the electrolyte flow rate on the anode side is 200 mL / h to 700 mL / h. Oxygen is introduced on the cathode side at a flow rate of 20 sccm to 50 sccm.

[0013] In the above technical solutions, when implemented based on a porous solid electrolyte reactor, The anion exchange membrane is any one of FAA-3-50, FAA-3-PK-75 or FAA-3-PK-130; The porous solid electrolyte is either Amberlite® IR120 or Dowex 50W X8; The proton exchange membrane is Nafion 115 or Nafion 117; Deionized water is introduced into the middle layer of the porous solid electrolyte reactor at a flow rate of 20 mL / h to 60 mL / h; deionized water or H2 is introduced into the anode side; when deionized water is introduced into the anode side, the flow rate is 180 mL / h to 300 mL / h; when H2 is introduced into the anode side, the flow rate is 20 sccm to 50 sccm.

[0014] In the above technical solution, the alkaline solution is any one of LiOH solution, NaOH solution, KOH solution or CsOH solution, and the concentration of the alkaline solution is 0.1 M to 2 M.

[0015] The beneficial effects of this invention are: This invention provides an oxygen-doped carbon catalyst for the electrocatalytic two-electron oxygen reduction synthesis of hydrogen peroxide, its preparation method, and its application. Using vegetable oil as an ideal precursor, a highly active oxygen-doped carbon catalyst is prepared. The unique combustion chemistry of vegetable oil allows for the in-situ construction of high-density defects and specific C=O functional groups in the carbon skeleton during formation, completely avoiding complex, expensive, and potentially polluting post-doping or post-oxidation steps. This invention significantly broadens the sources of raw materials, reduces raw material costs and the risk of regional dependence, uses inexpensive and readily available raw materials, and employs a simple, controllable, and easily implemented preparation method that is environmentally friendly and suitable for large-scale production and application. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of the carbon material based on tung oil soot prepared in Example 1 of the present invention.

[0017] Figure 2 This is a transmission electron microscope image of the carbon material based on tung oil soot prepared in Example 1 of the present invention.

[0018] Figure 3 This is the X-ray diffraction pattern of the carbon material based on tung oil soot prepared in Example 1 of this invention.

[0019] Figure 4 The X-ray photoelectron spectroscopy full spectrum and high-resolution fine spectra of C 1s and O 1s of the carbon material based on tung oil soot prepared in Example 1 of this invention are shown.

[0020] Figure 5 This is the Raman spectrum of the carbon material based on tung oil soot prepared in Example 1 of this invention.

[0021] Figure 6 This is a scanning electron microscope image of the carbon material based on flaxseed oil soot prepared in Example 2 of the present invention.

[0022] Figure 7 This is a schematic diagram of the flow tank reactor structure used in Embodiment 3 of the present invention.

[0023] Figure 8 This is the voltage-current curve of the carbon material prepared in Example 1 of the present invention, tested in a flow cell reactor in 1 M KOH electrolyte.

[0024] Figure 9 The diagram shows the Faraday efficiency and hydrogen peroxide yield at different current densities when the carbon material prepared in Example 1 of this invention is electrolyzed in 1 M KOH electrolyte in a flow cell reactor.

[0025] Figure 10 This is a schematic diagram of the porous solid electrolyte reactor structure used in Embodiments 4 and 5 of the present invention.

[0026] Figure 11 This is the voltage-current curve measured when the carbon material prepared in Example 1 of this invention undergoes an oxygen evolution reaction at the anode in a porous solid electrolyte reactor.

[0027] Figure 12 The diagram shows the Faraday efficiency and hydrogen peroxide yield at different current densities when the carbon material prepared in Example 1 of this invention undergoes an oxygen evolution reaction at the anode in a porous solid electrolyte reactor.

[0028] Figure 13 This is the voltage-current curve measured when the carbon material prepared in Example 1 of this invention undergoes a hydrogen oxidation reaction at the anode in a porous solid electrolyte reactor.

[0029] Figure 14 The diagram shows the Faraday efficiency of the carbon material prepared in Example 1 of this invention when hydrogen oxidation occurs at the anode in a porous solid electrolyte reactor, and the hydrogen peroxide production is shown in the constant current electrolysis at different current densities. The diagram also shows the hydrogen peroxide yield at different current densities.

[0030] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1 A method for preparing a catalyst for the electrocatalytic synthesis of hydrogen peroxide includes the following steps: In a well-ventilated combustion chamber (to safely remove combustion byproducts, including unburned carbon soot, and to prevent the accumulation of combustible gases), refined tung oil in an alcohol lamp is ignited. A clean, cooled metal or ceramic plate is suspended 10 cm above the flame to collect the black soot produced during combustion. Collection continues for approximately 2 hours, yielding a final black powdery carbon material, which is the oxygen-doped carbon catalyst based on tung oil soot, with a catalyst weight of approximately 5 g.

[0033] The catalyst material prepared in this embodiment was characterized as follows: Scanning electron microscope images ( Figure 1 The data shows that the carbon material is an aggregate formed by the disordered agglomeration of a large number of nanoscale spherical particles; Transmission electron microscope images ( Figure 2 Further confirmation revealed that the size of these primary particles was between 20 nm and 50 nm, the material had an amorphous structure, and no obvious long-range ordered graphite lattice was observed. X-ray diffraction pattern ( Figure 3 Two broadened diffraction peaks appear at approximately 24° and 44°, corresponding to the (002) and (100) crystal planes of graphitic carbon, respectively. The broadened peak shape indicates that its crystallinity is low and it is mainly composed of amorphous carbon. X-ray photoelectron spectroscopy full spectrum ( Figure 4 a) Confirmed that the material is mainly composed of carbon and oxygen elements; high-resolution C1s spectrum ( Figure 4 b) Peaks can be fitted to groups such as CC / C=C (284.6 eV), CO (286.2 eV), and C=O (288.5 eV); high-resolution O 1s spectrum ( Figure 4 c) The peaks can be fitted as O=C (531.6 eV) and OC (533 eV); the calculated surface oxygen content is 15.8%, of which O=C functional groups account for 47.93% of the total oxygen content. This indicates that the material surface is rich in oxygen that may act as 2e-e-coatings. - -Carbonyl functional group at the ORR active site; Raman spectroscopy was performed on the material, and the results are as follows: Figure 5 As shown: the spectrum at 1350 cm⁻¹ -1 and 1580 cm -1 Two distinct characteristic peaks appeared nearby, corresponding to the D peak of carbon materials (representing sp). 3 Carbon or defect / disordered structure) and G peak (representing sp) 2 (Hybrid graphite carbon). Calculations show that the intensity ratio of the D peak to the G peak (I...) D / I GThe value is 1.17. This value clearly indicates that the prepared carbon material has significant structural disorder and high defect density. These defect sites are considered to be conducive to the adsorption and activation of oxygen molecules and may serve as active centers for highly selective generation of H2O2.

[0034] Example 2 A method for preparing a catalyst for the electrocatalytic synthesis of hydrogen peroxide, specifically comprising: Following the same method as in Example 1, refined tung oil was replaced with refined linseed oil, resulting in approximately 4.3 g of soot. The scanning electron microscope image of the resulting carbon material is shown below. Figure 6 As shown, this carbon material is also an aggregate formed by the disordered agglomeration of a large number of nanoscale spherical particles.

[0035] Example 3 The application of the catalyst prepared in Example 1 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide specifically includes the following steps: S1. Electrode preparation: (i) Preparation of working electrode: 10 mg of the catalyst prepared in Example 1 was dispersed in a mixture of 1 mL isopropanol and 20 μL of 5 wt% Nafion solution, and sonicated for 30 min to form a uniform ink; subsequently, the ink was uniformly coated on a 3*3 cm electrode. 2 On the gas diffusion electrode YLS-30T, the catalyst loading is approximately 0.6 mg cm⁻¹. -2 Air dry at room temperature for later use; (ii) Electrode preparation: 40 mg of iridium oxide catalyst was dispersed in a mixture of 1 mL deionized water, 4 mL isopropanol, and 80 μL of 5 wt% Nafion solution, and sonicated for 30 minutes to form a uniform ink. This ink was then uniformly coated onto a 3*3 cm electrode. 2 The catalyst loading on the platinum-plated titanium felt is approximately 3 mg cm⁻¹ -2 Let it air dry at room temperature for later use.

[0036] S2, preparation of hydrogen peroxide via electrocatalytic two-electron oxygen reduction reaction: use Figure 7 The flow cell reactor shown uses the electrode prepared above as the working electrode, iridium oxide as the counter electrode, and 1 M KOH solution as the electrolyte, which enters the cathode chamber at a flow rate of 120 mL / h. Oxygen is continuously introduced into the cathode chamber at a flow rate of 30 sccm to ensure sufficient oxygen supply to the catalyst surface. 1 M KOH is circulated in the anode chamber at a flow rate of 600 mL / h. Electrochemical tests are performed after the anode and cathode chambers are separated by an anion exchange membrane FAA-3-PK-75.

[0037] First, a constant current test was performed, and the voltage-current curves under different current densities are shown below. Figure 8 As shown, tests were conducted at different constant currents (specifically 50, 100, 200, 300, 400, and 500 mA cm⁻¹). -2 Electrolysis was performed for 2 minutes at each of the six current densities, and the electrolyte at the cathode chamber outlet was collected. The Faraday efficiency (FE) was calculated based on the amount of electricity passed and the number of moles of H2O2 generated. The results are as follows: Figure 9 As shown, in the range of 100-500 mA cm -2 It maintains a hydrogen peroxide Faraday efficiency greater than 80% over a wide current range; simultaneously, the H2O2 formation rate can be calculated based on the current density and FE at 500 mA cm⁻¹. -2 Under the given total current, the H2O2 formation rate can reach 7.6 mmol h⁻¹. -1 cm -2 .

[0038] Example 4 The application of the catalyst prepared in Example 1 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide specifically includes the following steps: S1. Electrode preparation: The electrode preparation method is as described in Example 3.

[0039] S2, preparation of hydrogen peroxide via electrocatalytic two-electron oxygen reduction reaction: use Figure 10 The solid electrolyte reactor shown uses the electrode prepared in Example 3 as the working electrode, iridium oxide as the counter electrode, Nafion 117 as the proton exchange membrane, Dowex 50W X8 as the solid electrolyte, and FAA-3-50 as the anion exchange membrane. After assembly, deionized water enters the intermediate chamber at a flow rate of 33.7 mL / h. Oxygen is continuously introduced into the cathode chamber at a flow rate of 30 sccm to ensure sufficient oxygen supply to the catalyst surface. Deionized water is circulated in the anode chamber at a flow rate of 180 mL / h. The product is then collected from the intermediate chamber for quantitative analysis.

[0040] A constant current test was performed, and the voltage-current curves under different currents are shown below. Figure 11 As shown, tests were conducted at different constant currents (specifically 25, 50, 75, 100, 150, and 200 mA cm⁻¹). -2 Electrolysis was performed for 2 minutes at each of the six current densities, and the electrolyte at the cathode chamber outlet was collected. The Faraday efficiency (FE) was calculated based on the amount of charge passed and the number of moles of H₂O₂ produced. The results are as follows: Figure 12 As shown, in the range of 50-200 mA cm -2 It maintains a hydrogen peroxide Faraday efficiency greater than 90% across the current density range.

[0041] Example 5 The application of the catalyst prepared in Example 1 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide specifically includes the following steps: S1. Electrode preparation: The electrode preparation method is as described in Example 3.

[0042] S2, preparation of hydrogen peroxide via electrocatalytic two-electron oxygen reduction reaction: use Figure 10 The solid electrolyte reactor shown uses the electrode prepared in Example 3 as the working electrode, a platinum-carbon catalyst as the counter electrode, a Nafion 117 proton exchange membrane, a Dowex 50W X8 solid electrolyte, and a FAA-3-50 anion exchange membrane. After assembly, deionized water enters the intermediate chamber at a flow rate of 33.7 mL / h. Oxygen is continuously introduced into the cathode chamber at a flow rate of 30 sccm to ensure sufficient oxygen supply to the catalyst surface. H2 is continuously introduced into the anode chamber at a flow rate of 30 sccm. The product is then collected from the intermediate chamber for quantitative analysis.

[0043] A constant current test was performed, and the voltage-current curves under different currents are shown below. Figure 13 As shown, tests were conducted at different constant currents (specifically 25, 50, 75, 100, 150, and 200 mA cm⁻¹). -2 Electrolysis was performed for 2 minutes at each of the six current densities, and the electrolyte at the cathode chamber outlet was collected. The Faraday efficiency (FE) was calculated based on the amount of charge passed and the number of moles of H₂O₂ produced. The results are as follows: Figure 14 As shown, in the range of 50-200 mA cm -2 It maintains a hydrogen peroxide Faraday efficiency greater than 90% across the current density range.

[0044] This invention utilizes the large amount of soot generated from the incomplete combustion of vegetable oil as a precursor. This soot, primarily composed of amorphous carbon and minor impurities, is typically considered a pollutant and discarded. This invention directly applies the biomass soot, after simple processing, to the electrocatalytic two-electron oxygen reduction reaction, achieving high-value utilization of biomass waste. It transforms waste into treasure, uses renewable raw materials, and is extremely low-cost, aligning with the concept of green and sustainable development. Simultaneously, it avoids the use of highly concentrated nitric acid and other acids with strong oxidizing properties and environmentally unfriendly characteristics. The carbon material prepared by this invention can be used as a highly efficient catalyst in reactors for the electrosynthesis of H2O2, providing a novel, low-cost catalyst solution for the green, distributed production of hydrogen peroxide.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a catalyst for the electrocatalytic synthesis of hydrogen peroxide, characterized in that: The preparation method is as follows: using vegetable oil as raw material, igniting the vegetable oil under insufficient oxygen conditions, and collecting the black soot formed by combustion, which is the catalyst.

2. The method for preparing the catalyst for the electrocatalytic synthesis of hydrogen peroxide according to claim 1, characterized in that: The specific condition of insufficient oxygen is as follows: a metal or ceramic plate is suspended above the flame of vegetable oil combustion, the baffle blocks the free diffusion of combustion products, and a confined combustion microenvironment is formed above the flame zone.

3. The method for preparing the catalyst for the electrocatalytic synthesis of hydrogen peroxide according to claim 1, characterized in that: The method for collecting the black soot formed by combustion is as follows: a metal plate or ceramic plate is suspended 2 cm to 15 cm above the flame of vegetable oil combustion, and the black soot formed by the incomplete combustion of vegetable oil is deposited on the metal plate or ceramic plate.

4. The method for preparing the catalyst for the electrocatalytic synthesis of hydrogen peroxide according to claim 1, characterized in that: The vegetable oil is at least one of tung oil, flaxseed oil, tallow tree oil, soybean oil, rapeseed oil, sunflower seed oil, sesame oil, or cottonseed oil.

5. The application of a catalyst prepared by the method according to any one of claims 1 to 4 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, characterized in that: The electrocatalytic two-electron oxygen reduction reaction to produce hydrogen peroxide is achieved using a flow cell reactor or a porous solid electrolyte reactor; the reactor uses a conductive substrate loaded with the catalyst prepared by any one of claims 1 to 4 as the cathode, and the catalyst loading is 0.2 mg / cm³. 2 ~0.8 mg / cm 2 .

6. The application of the catalyst according to claim 5 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, characterized in that: The flow cell reactor includes a cathode, an anion exchange membrane, and an anode arranged in sequence; the porous solid electrolyte reactor includes a cathode, an anion exchange membrane, a porous solid electrolyte layer, a proton exchange membrane, and an anode arranged in sequence.

7. The application of the catalyst according to claim 6 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, characterized in that: When implemented based on a flow cell reactor The anion exchange membrane is any one of FAA-3-50, FAA-3-PK-75 or FAA-3-PK-130; The electrolyte in the reactor is an alkaline solution. The electrolyte flow rate on the cathode side is 90 mL / h to 150 mL / h, and the electrolyte flow rate on the anode side is 200 mL / h to 700 mL / h. Oxygen is introduced on the cathode side at a flow rate of 20 sccm to 50 sccm.

8. The application of the catalyst according to claim 6 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, characterized in that: When implemented based on a porous solid electrolyte reactor The anion exchange membrane is any one of FAA-3-50, FAA-3-PK-75 or FAA-3-PK-130; The porous solid electrolyte is Amberlite. ® IR120 or Dowex 50W X8; The proton exchange membrane is Nafion 115 or Nafion 117; Deionized water is introduced into the porous solid electrolyte layer of the porous solid electrolyte reactor at a flow rate of 20 mL / h to 60 mL / h; deionized water or H2 is introduced into the anode side; when deionized water is introduced into the anode side, the flow rate of deionized water is 180 mL / h to 300 mL / h; when H2 is introduced into the anode side, the flow rate of H2 is 20 sccm to 50 sccm.

9. The application of the catalyst according to claim 7 in the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, characterized in that: The alkaline solution is any one of LiOH solution, NaOH solution, KOH solution or CsOH solution, and the concentration of the alkaline solution is 0.1 M to 2 M.

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