Method for producing green hydrogen by coupling biomass oxidation with magnetic field enhanced electrocatalysis

Abstract

This invention discloses a method for producing green hydrogen through magnetic field-enhanced electrocatalytic biomass oxidation coupled with the following steps: immersing a metal substrate in a metal salt solution in contact with air to obtain a self-supporting precursor through natural corrosion; subjecting the self-supporting precursor to phosphating under an inert gas atmosphere; subjecting the phosphated self-supporting precursor to surface electrooxidation to obtain a magnetic field-responsive monolithic electrocatalyst; using the monolithic electrocatalyst as the anode and cathode of the electrocatalytic coupling reaction to form a dual-electrode system; adding an alkaline solution containing biomass as the electrolyte in a membrane-free electrolyzer; applying a magnetic field around the anode and cathode, with the magnetic field lines passing through the electrodes, which are immersed in the electrolyte; the anode undergoing the biomass electrocatalytic oxidation reaction, and the cathode undergoing the hydrogen evolution reaction. This invention couples hydrogen production from water electrolysis with biomass oxidation and accelerates the overall reaction rate by applying an external magnetic field, thereby improving the efficiency of hydrogen production at the cathode and FDCA generation at the anode.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic biomass oxidation technology, and in particular to a method for producing green hydrogen by coupling magnetic field-enhanced electrocatalytic biomass oxidation. Background Technology

[0002] To address the scarcity of fossil resources and global warming, the development of renewable energy is essential. Hydrogen, as a green energy carrier, possesses advantages such as high calorific value and clean, renewable nature, and will play a significant role in the field of sustainable energy. Electrolysis of water is an ideal method for producing high-purity hydrogen, which is also known as "green hydrogen." Currently, in the industrial and research fields of water electrolysis for hydrogen production, precious metal catalysts remain the most effective. However, the limited reserves and high prices of these catalysts restrict their large-scale application in industrial production. Therefore, there is an urgent need to develop low-cost, high-efficiency water electrolysis catalysts using transition metals and non-metals.

[0003] On the other hand, the kinetics of the oxygen evolution reaction (OER) at the anode in water electrolysis are slow, which not only greatly limits the overall reaction rate of water electrolysis, but also makes the oxygen produced by the OER less valuable. Biomass electro-oxidation has greater thermodynamic and kinetic advantages than the OER, and choosing biomass electro-oxidation to replace the OER can lower the overall energy barrier of the reaction. Bio-based 2,5-furandicarboxylic acid (FDCA), due to its conjugated rigid ring and diacid structure similar to terephthalic acid (PTA), can replace PTA to produce poly(ethylene furanate dicarboxylate) (PEF), which has superior performance compared to polyethylene terephthalate (PET). FDCA can be used to produce bio-based biodegradable plastics, semi-aromatic nylon, unsaturated resins, etc. In addition, FDCA can also be used in fine chemicals, pharmaceutical synthesis, chiral catalysis, and other fields, showing huge market potential. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is how to simultaneously produce hydrogen and generate FDCA.

[0005] To address the aforementioned technical problems, this invention provides a method for producing green hydrogen via magnetic field-enhanced electrocatalytic biomass oxidation coupled with green hydrogen production, comprising the following steps:

[0006] S1. Immerse the metal substrate in a metal salt solution that is in contact with air, and obtain a self-supporting precursor through natural corrosion.

[0007] S2. Phosphate the self-supporting precursor in an inert gas atmosphere;

[0008] S3. The phosphating-treated self-supporting precursor is subjected to surface electro-oxidation treatment to obtain a magnetic field-responsive monolithic electrocatalyst.

[0009] S4. An integral electrocatalyst is used as the anode and cathode of the electrocatalytic reaction to form a dual-electrode system. An alkaline solution containing biomass is added as the electrolyte in a membraneless electrolytic cell.

[0010] S5. Apply a magnetic field around the anode and cathode. The magnetic field lines pass through the electrodes, which are immersed in the electrolyte. The anode undergoes a biomass electrocatalytic oxidation reaction, and the cathode undergoes a hydrogen evolution reaction.

[0011] This invention prepares a monolithic catalyst with magnetic field responsiveness. The monolithic catalyst has good biomass oxidation ability and good hydrogen evolution performance. It can couple hydrogen production from water electrolysis and biomass oxidation. Hydrogen evolution occurs at the cathode while biomass oxidation occurs at the anode, and two high-value-added products are obtained simultaneously. By applying an external magnetic field, the overall reaction rate is accelerated, and the efficiency of hydrogen production at the cathode and FDCA generation at the anode is improved.

[0012] In a preferred or optional embodiment, in step S4, the magnetic field strength applied around the electrode is 0.1–0.5 T. The magnetic field has a significant modulating effect on the state and migration of charges. The magnetic field can promote the electrocatalytic reaction in the following ways: (1) adjusting the arrangement of the spin electrons of the catalyst and the oxygen adsorbed on its surface, thereby optimizing the reaction pathway; (2) the Lorentz force can accelerate the mass transfer of ions in the electrolyte; (3) accelerating the charge transfer at the electrode-electrolyte interface. The above method uses a magnetic field-responsive electrocatalyst as the working electrode and adopts a non-contact control method. By applying a magnetic field, it can enhance the hydrogen evolution and biomass oxidation reactions, avoiding overly complex and demanding design and preparation processes for the electrocatalyst, and significantly reducing the cost of the electrocatalytic reaction.

[0013] In a preferred or optional embodiment, in step S5, the operating voltage of the electrocatalytic reaction is 1.6–2.2V, and the time is 1–24 hours. Limiting the operating voltage and time is crucial; if the operating voltage is too low, the magnetic field effect is insignificant, while if the operating voltage is too high, energy consumption will increase, the oxygen evolution reaction will be severe, and the selectivity of the biomass oxidation reaction will be reduced.

[0014] In a preferred or optional embodiment, in step S5, the biomass in the electrolyte is a furan compound, selected from at least one of 2,5-furandimethyl, 5-hydroxymethylfurfural, 2,5-diformylfuran, 5-hydroxymethyl-2-furancarboxylic acid, and 5-formyl-2-furancarboxylic acid, and the concentration of biomass in the electrolyte is 10–1000 mM. The above method has a good catalytic oxidation effect on furan-based biomass, which can significantly shorten the reaction time and improve the yield and conversion rate of biomass.

[0015] In a preferred or optional embodiment, in step S1, the composition of the metal substrate is selected from any one or more of cobalt, nickel, iron, and copper; the form of the metal substrate is selected from any one of metal foam, metal sheet, and metal foil; and the metal salt in the metal salt solution is selected from any one or more combinations of sulfates, nitrates, and hydrochlorides of transition metals iron, cobalt, and nickel.

[0016] In a preferred or optional embodiment, in step S1, the concentration of the metal salt solution is 1–2000 mM, and the natural corrosion time is 0.1–72 h.

[0017] In step S1, the metal substrate is immersed in a metal salt solution that is in contact with air, and then naturally corrodes at room temperature through spontaneous corrosion. The concentration of the metal salt solution affects the natural corrosion rate. Generally speaking, the higher the concentration, the faster the natural corrosion rate and the shorter the time required. By controlling the concentration of the metal salt solution and the natural corrosion time, self-supporting precursors with different structural properties can be obtained.

[0018] In a preferred or optional embodiment, step S2 specifically includes: placing a phosphorus source upstream of a tubular furnace and a self-supporting precursor downstream of the tubular furnace; introducing inert gas into the tubular furnace and heating it to 300–600°C at a heating rate of 1–5°C / min, holding it at that temperature for 1–3 hours. The phosphorus source decomposes upon heating into phosphorus-containing compound vapor or vaporizes after heating, and comes into contact with the self-supporting precursor material as the inert gas flows, further undergoing a phosphating reaction with the self-supporting precursor. A suitable process temperature must be selected; if the temperature is too low, the phosphorus powder will not reach the vaporization temperature; if the temperature is too high, energy consumption is high and there are certain dangers.

[0019] In preferred or optional embodiments, the inert gas is selected from any one or more of nitrogen, argon, and helium, and the gas volumetric flow rate of the inert gas is 5–100 mL / min. Controlling the gas volumetric flow rate within a suitable range is crucial; too high a flow rate hinders sufficient contact and reaction between the phosphorus-containing vapor and the self-supporting precursor, leading to rapid phosphorus source loss and high gas consumption; too low a flow rate results in low uniformity of the phosphating region.

[0020] The precursors for metals such as cobalt, nickel, iron, and copper through corrosion are usually hydroxides with a thickness of micrometers or even tens of micrometers and poor conductivity. The phosphating step transforms the hydroxides into highly conductive phosphides with metal-like properties. In addition, phosphating can significantly improve the magnetic field response performance of self-supporting precursors, thereby affecting the surface catalytic performance.

[0021] In a preferred or optional embodiment, step S3 specifically includes: using the phosphated self-supporting precursor as the working electrode, setting a counter electrode and a reference electrode to form a three-electrode system, and immersing the working electrode in an electrolyte for constant current oxidation at a current density of 2–50 mA·cm⁻¹.-2 The processing time is 0.05 to 5 hours.

[0022] In a preferred or optional embodiment, in step S3, the electrolyte is a sodium hydroxide and / or potassium hydroxide solution with a concentration of 0.1 to 5 M, the counter electrode is selected from any one of platinum sheet, carbon rod, and nickel, and the reference electrode is selected from any one of mercury / mercuric oxide, silver / silver chloride, and saturated calomel.

[0023] Anodic electro-oxidation of phosphide surfaces can form high-valence catalytically active sites for subsequent electrocatalytic oxidation. This Mott-Schottky interface heterostructure, characterized by high internal conductivity and shallow, highly catalytically active surfaces, facilitates charge redistribution and rapid transfer, significantly enhancing electrocatalytic performance. Therefore, during preparation, phosphating must be thorough, and the oxidation depth of the electro-oxidation process must be controlled to avoid reducing conductivity. Controlling the current and time during the surface electro-oxidation process can meet the catalyst's performance requirements. For example, too low a current density prolongs the electro-oxidation time and increases cost; too high a current density increases the oxide layer on the catalyst surface and reduces conductivity.

[0024] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention uses an integral electrocatalyst as the anode and cathode of the electrocatalytic reaction. While hydrogen evolution occurs at the cathode, biomass oxidation occurs at the anode, resulting in two high-value-added products. Furthermore, the integral electrocatalyst has magnetic response properties, and by applying an external magnetic field, the overall reaction rate can be accelerated, improving the efficiency of hydrogen production at the cathode and FDCA generation at the anode.

[0026] The preparation method of monolithic electrocatalysts is simple, the reaction conditions are mild, and the prepared catalysts have good ability to oxidize biomass and also have good hydrogen evolution performance. Compared with powdered catalysts, monolithic electrocatalysts are easier to separate from products. FDCA is generated at the anode while hydrogen is evolved at the cathode. Oxygen generation can be avoided by simply controlling the potential, and there is no need to use expensive membranes, which reduces the cost of production equipment.

[0027] This invention utilizes magnetic field-controlled electrocatalytic biomass oxidation coupled with hydrogen evolution reaction, providing a green and non-contact method for regulating reaction performance. This avoids complex preparation processes such as electrocatalyst structure construction, interface design, and morphology control, and has high economic value and promising industrial application prospects. Attached Figure Description

[0028] Figure 1 This is a SEM image showing the microstructure of the monolithic electrocatalyst in Example 1 of the present invention.

[0029] Figure 2This is a comparison of XPS images of the monolithic electrocatalyst surface before and after oxidation in Example 1 of the present invention.

[0030] Figure 3 This is a diagram showing the hydrogen evolution performance of the cathode in Embodiment 1 of the present invention.

[0031] Figure 4 This is a linear voltammetric scan of the two-electrode system in Embodiment 1 of the present invention.

[0032] Figure 5 This is a graph showing the yield of hydrogen and FDCA and the relationship between the reaction time required in Example 1 of the present invention.

[0033] Figure 6 This is a current-time curve of the two-electrode system in Embodiment 2 of the present invention with and without a magnetic field. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0037] A specific embodiment of the present invention provides a method for producing green hydrogen by magnetic field-enhanced electrocatalytic biomass oxidation coupled with green hydrogen production, which is prepared by the following method:

[0038] S1. Immerse the metal substrate in a metal salt solution that is in contact with air to obtain a self-supporting precursor through natural corrosion.

[0039] In specific embodiments, the metal substrate can be composed of cobalt, nickel, iron, copper, etc., and can be in the form of metal foam, metal sheet, metal foil, etc.; a typical metal substrate is cobalt foam. The three-dimensional structure of the metal substrate exposes more active sites, which is beneficial for enhancing the stability of the electrocatalyst.

[0040] In a specific embodiment, the solvent in the metal salt solution is water, and the metal salt is selected from any one or more combinations of sulfates, nitrates, and hydrochlorides of transition metals such as iron, cobalt, and nickel, with a concentration of 1 to 2000 mM. Typical concentrations include 5 mM, 10 mM, 20 mM, 50 mM, 100 mM, 200 mM, 300 mM, 400 mM, 500 mM, 600 mM, 700 mM, 800 mM, 1000 mM, 1500 mM, and 2000 mM.

[0041] In a specific embodiment, natural corrosion is carried out at room temperature for a time ranging from 0.1 to 72 hours, with typical natural corrosion times including 0.1 hours, 0.5 hours, 1 hour, 6 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 ​​hours, and 72 hours. Natural corrosion is conducted under mild conditions, the preparation method is simple, and it is easy to scale up for mass production.

[0042] S2. Phosphating the self-supporting precursor in an inert gas atmosphere. The specific steps are as follows: place the phosphorus source upstream of the tube furnace, place the self-supporting precursor downstream of the tube furnace, introduce inert gas into the tube furnace, heat to the set temperature, and then hold at that temperature.

[0043] In a specific embodiment, the phosphorus source is selected from one or more of sodium hypophosphite, potassium hypophosphite, red phosphorus, white phosphorus, potassium dihydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate, preferably sodium hypophosphite.

[0044] In a specific embodiment, the inert gas is selected from any one or more of nitrogen, argon, and helium, and the gas volume flow rate of the inert gas is 5 to 100 mL / min.

[0045] In a specific embodiment, during the phosphating process, the heating rate of the tubular furnace is 1–5 °C / min; the holding time is 1–3 h; and the holding temperature is 300–600 °C.

[0046] S3. The phosphating self-supporting precursor is subjected to surface electro-oxidation treatment to obtain a magnetic field-responsive monolithic electrocatalyst. The specific steps are as follows: the phosphating self-supporting precursor is used as the working electrode, and a counter electrode and a reference electrode are set to form a three-electrode system. The working electrode is immersed in the electrolyte for surface electro-oxidation treatment.

[0047] In a specific embodiment, the counter electrode is selected from any one of platinum sheet, carbon rod, nickel sheet, platinum wire, and platinum mesh, preferably a platinum sheet; the reference electrode is selected from any one of mercury / mercury oxide, silver / silver chloride, and saturated calomel, preferably a mercury / mercury oxide electrode.

[0048] In a specific embodiment, the electrolyte is an alkaline solution containing sodium hydroxide and / or potassium hydroxide, with a concentration of 0.1 to 5 M, typical concentrations including 0.1 M, 0.5 M, 1 M, 2 M, 3 M, 4 M, 5 M, etc., and preferably 1 M potassium hydroxide.

[0049] In a specific embodiment, the surface electro-oxidation treatment employs constant current oxidation or constant potential oxidation, with the current density of constant current oxidation being 2–50 mA·cm⁻¹. -2 The working electrode potential for constant potential oxidation is 1.3–2 V vs. RHE, and the surface electro-oxidation treatment time is 0.1–5 h. Surface electro-oxidation treatment can generate high-valence metal ions from the self-supporting precursor, thereby enhancing its electrocatalytic performance.

[0050] The above preparation method is simple and mild, and can obtain a structurally stable high-performance electrocatalyst with magnetic field responsiveness.

[0051] S4. An integral electrocatalyst is used as the anode and cathode of the electrocatalytic reaction to form a dual-electrode system. An alkaline solution containing biomass is added as the electrolyte in a membraneless electrolytic cell.

[0052] In a specific embodiment, the electrolyte is an alkaline solution containing biomass, and the solvent is water; the biomass is a furan compound, and the concentration of the biomass is 10-1000 mM, with typical concentrations including 10 mM, 20 mM, 50 mM, 80 mM, 100 mM, 200 mM, 400 mM, 800 mM, 1000 mM, etc.; typical biomass includes 2,5-furandimethyl, 5-hydroxymethylfurfural, 2,5-dicarboxyfuran, 5-hydroxymethyl-2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid, etc.

[0053] S5. Apply a magnetic field around the anode and cathode. The magnetic field lines pass through the electrodes, which are immersed in the electrolyte. The anode undergoes a biomass electrocatalytic oxidation reaction, and the cathode undergoes a hydrogen evolution reaction.

[0054] In a specific embodiment, the magnetic field strength applied around the electrode is 0.05 to 0.5T. If the magnetic field strength is too small, the effect on the electrocatalytic oxidation of biomass is not obvious. However, the maximum magnetic field strength is limited by the magnetic field strength of the permanent magnet. The magnetic field strength within the above range can enhance the electrocatalytic oxidation reaction of biomass.

[0055] In a specific embodiment, the operating voltage of the electrocatalytic reaction is 1.6–2.2V, and the time is 1–24h. The magnetic field effect is not significant at the operating voltage; if the operating voltage is too high, energy consumption increases, the oxygen evolution reaction becomes severe, and the selectivity of the biomass oxidation reaction decreases.

[0056] The above method uses a monolithic electrocatalyst as both the anode and cathode of the electrocatalytic reaction. Hydrogen evolution occurs at the cathode while biomass oxidation occurs at the anode, simultaneously yielding two high-value-added products. Furthermore, the monolithic electrocatalyst exhibits magnetic responsiveness, and by applying an external magnetic field, the overall reaction rate can be accelerated, improving the efficiency of hydrogen production at the cathode and FDCA generation at the anode. Employing a non-contact control method, enhancing both hydrogen evolution and biomass oxidation reactions simply by applying a magnetic field avoids overly complex and demanding design and preparation processes for the electrocatalyst, significantly reducing the cost of the electrocatalytic reaction. This method possesses high economic value and promising industrial application prospects.

[0057] The technical effects of the present invention will be described below with reference to specific embodiments.

[0058] Example 1

[0059] (1) The cobalt foam substrate was ultrasonically cleaned in acetone and ethanol for 10 min each, and then dried for later use.

[0060] (2) Prepare a 10mM nickel sulfate solution, immerse the treated foamed cobalt in this solution, expose it to air, allow it to corrode naturally at room temperature for 24 hours, remove it, rinse it with deionized water, and air dry it naturally.

[0061] (3) Place the obtained material downstream of the tube furnace, weigh 1g of sodium hypophosphite and place it upstream of the tube furnace, calcine at 300℃ for 1h under nitrogen atmosphere, the heating rate of the tube furnace is 5℃ / min, the nitrogen flow rate is 10mL / min, and then cool down naturally.

[0062] (4) In a 1M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 5 mA·cm⁻¹ -2 Oxidation at a current density of [value missing] for 5 min yielded a monolithic electrocatalyst. The microstructure of the monolithic electrocatalyst is shown in [details missing]. Figure 1 As shown, a hexagonal sheet-like bifunctional electrocatalyst of NiCoP-Ni(Co)OOH was obtained. X-ray photoelectron spectroscopy analysis of the materials before and after oxidation treatment yielded the following results: Figure 2 As shown, after partial oxidation treatment of the material surface, the outermost phosphide is transformed into more reactive hydroxyl oxides.

[0063] (5) Using the monolithic electrocatalyst prepared in step (4) as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, a three-electrode system was obtained. A comparative example was set up, using cobalt foam metal as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, to obtain a three-electrode system. The cathodic hydrogen evolution performance of the catalyst was tested. The current density of the monolithic electrocatalyst electrode and the comparative example cobalt foam electrode was tested using linear sweep voltammetry with 1M KOH solution and 1M KOH solution containing 100mM BHMF as electrolytes, respectively. The results are as follows: Figure 3 As shown, the monolithic electrocatalyst exhibits good hydrogen evolution performance, and the addition of biomass BHMF does not affect the hydrogen evolution performance, indicating that the monolithic electrocatalyst has high hydrogen evolution selectivity.

[0064] (6) Using the monolithic electrocatalyst prepared in step (4) as the anode and cathode, a dual-electrode system was formed. Voltammetry curves were measured using 1M KOH solution and 1M KOH solution containing 10mM BHMF as electrolytes, respectively, with and without a magnetic field around the electrodes and with a magnetic field of 0.48T applied. The results are as follows: Figure 4 As shown, the results indicate that in the two-electrode system, the voltage required for biomass oxidation coupled with hydrogen evolution is lower than that for simple water electrolysis. After the magnetic field is added, the current further increases, indicating that the catalyst performance is further improved.

[0065] (7) Place 5 mL of 1 M KOH electrolyte with a BHMF concentration of 10 mM in a membrane-free electrolytic cell. Use the monolithic electrocatalyst prepared in step (4) as the anode and cathode, respectively, to assemble a dual-electrode system. Set the voltage to 1.7 V. Seal the beaker, connect it to a tubing, and insert the other end of the tubing into an inverted graduated cylinder filled with water. Collect the hydrogen gas generated at the cathode using the water displacement method. Test the yield of hydrogen and FDCA and the reaction time required for the corresponding yield under conditions of no magnetic field and a magnetic field of 0.48 T around the electrodes. The results are as follows: Figure 5 As shown in the figure. The results show that at a voltage of 1.7V, the hydrogen yield is 65.30% and the FDCA yield is 55.59%; after adding a magnetic field, the hydrogen yield is 69.38% and the FDCA yield is 82.29%; under the same reaction conditions, the reaction time is shortened by 1.07 hours, and the magnetic field has a significant effect on improving the reaction rate.

[0066] Example 2

[0067] (1) The cobalt foam substrate was ultrasonically cleaned in acetone and ethanol for 10 min each, and then dried for later use.

[0068] (2) Prepare a mixed metal salt solution of 5mM nickel sulfate and 5mM ferric nitrate, immerse the treated foamed cobalt in this solution, expose it to air, and allow it to corrode naturally at room temperature for 12 hours. Remove it, rinse it with deionized water, and let it air dry.

[0069] (3) Place the obtained material downstream of the tube furnace, weigh 0.5g of sodium hypophosphite and place it upstream of the tube furnace. Calcinate at 300℃ for 1h under a nitrogen atmosphere. The heating rate of the tube furnace is 5℃ / min, the nitrogen flow rate is 10mL / min, and the material is allowed to cool naturally.

[0070] (4) In a 1M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 10 mA·cm⁻¹ -2 Oxidation was performed at a current density of 10 min to obtain a monolithic electrocatalyst.

[0071] (5) Using the monolithic electrocatalyst obtained in step (4) as the anode and cathode, a dual-electrode system was formed. A 1M KOH solution containing 100mM BHMF was added as the electrolyte in a membrane-free electrolytic cell. The voltage of the dual-electrode system was set to 1.8V. The current density was measured using linear sweep voltammetry with and without a magnetic field around the working electrode, and with a magnetic field of 0.48T applied. Specifically, after 200s of reaction, a magnetic field was added, and after 100s of reaction, the magnetic field was removed. The results are as follows: Figure 6 As shown, the results indicate that the current density is higher in the presence of a magnetic field, with the reaction current density increasing by approximately 7 mA·cm⁻¹. -2 This indicates that the catalyst has magnetic field responsiveness, and applying a magnetic field enhances the catalytic reaction.

[0072] (6) 5 mL of 1 M KOH electrolyte with a BHMF concentration of 10 mM was placed in a membraneless electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.725 V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.48 T magnetic field. At 1.725 V, the hydrogen yield was 60.13% and the FDCA yield was 51.13%. After adding a 0.48 T magnetic field, the hydrogen yield was 65.83% and the FDCA yield was 84%. Under the same reaction conditions, the reaction time was shortened by 1.53 hours.

[0073] Example 3

[0074] (1) Clean the nickel substrate with acetone and ethanol for 10 min each, and dry it for later use.

[0075] (2) Prepare a 50mM ferric chloride metal salt solution, immerse the treated nickel sheet in this solution, expose it to air, allow it to corrode naturally at room temperature for 0.5h, remove it, rinse it with deionized water, and air dry it naturally.

[0076] (3) Place the obtained material downstream of the tube furnace, weigh 1g of potassium hypophosphate and place it upstream of the tube furnace, calcine at 500℃ for 2h under nitrogen atmosphere, the heating rate of the tube furnace is 10℃ / min, the nitrogen flow rate is 20mL / min, and then cool down naturally.

[0077] (4) In a 5M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 20 mA·cm⁻¹ -2 Oxidation at a current density of 1 h yielded a monolithic electrocatalyst.

[0078] (5) A 1M KOH electrolyte with a BHMF concentration of 100mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.4V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.3T magnetic field. At 1.4V, the hydrogen yield was 61.38% and the FDCA yield was 54.77%. After adding a 0.3T magnetic field, the hydrogen yield was 65.71% and the FDCA yield was 86.99%. Under the same reaction conditions, the reaction time was shortened by 1.84 hours.

[0079] Example 4

[0080] (1) The cobalt foam substrate was ultrasonically cleaned in acetone and ethanol for 10 min each, and then dried for later use.

[0081] (2) Prepare a 1mM nickel sulfate metal salt solution, immerse the treated foamed cobalt in this solution, expose it to air, allow it to corrode naturally at room temperature for 6 hours, remove it, rinse it with deionized water, and air dry it naturally.

[0082] (3) Place the obtained material downstream of the tube furnace, weigh 1g of sodium hypophosphite and place it upstream of the tube furnace, calcine at 250℃ for 1.5h under nitrogen atmosphere, the heating rate of the tube furnace is 4℃ / min, the nitrogen flow rate is 10mL / min, and then cool down naturally.

[0083] (4) In a 1M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 10 mA·cm⁻¹ -2 Oxidation at a current density for 5 hours yielded a monolithic electrocatalyst.

[0084] (5) A 1M KOH electrolyte with a BHMF concentration of 50mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.525V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.5T magnetic field. At 1.525V, the hydrogen yield was 67.28% and the FDCA yield was 52.14%. After adding a 0.5T magnetic field, the hydrogen yield was 73.57% and the FDCA yield was 77.25%. Under the same reaction conditions, the reaction time was shortened by 1.19 hours.

[0085] Example 5

[0086] (1) Clean the cobalt substrate with acetone and ethanol for 10 min each, and dry it for later use.

[0087] (2) Prepare a 4mM iron sulfate metal salt solution, immerse the treated cobalt sheet in this solution, expose it to air, and allow it to corrode naturally at room temperature for 20 hours. Remove the sheet, rinse it with deionized water, and air dry it naturally.

[0088] (3) Place the obtained material downstream of the tube furnace, weigh 1g of dipotassium hydrogen phosphate and place it upstream of the tube furnace. Calcinate at 300℃ for 2h under a nitrogen atmosphere. The heating rate of the tube furnace is 5℃ / min, the nitrogen flow rate is 10mL / min, and the material is allowed to cool naturally.

[0089] (4) In a 2M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 25 mA·cm⁻¹ -2 Oxidation at a current density of 1.5 h yielded a monolithic electrocatalyst.

[0090] (5) A 1M KOH electrolyte with a BHMF concentration of 500mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.4V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.48T magnetic field. At 1.4V, the hydrogen yield was 68.4% and the FDCA yield was 54.55%. After adding a 0.48T magnetic field, the hydrogen yield was 71.9% and the FDCA yield was 85.07%. Under the same reaction conditions, the reaction time was shortened by 1.62 hours.

[0091] Example 6

[0092] (1) Clean the copper substrate with acetone and ethanol for 10 min each, and dry it for later use.

[0093] (2) Prepare a 50mM cobalt sulfate metal salt solution, immerse the treated copper sheet in this solution, expose it to air, and allow it to corrode naturally at room temperature for 36 hours. Remove the sheet, rinse it with deionized water, and let it air dry.

[0094] (3) Place the obtained material downstream of the tube furnace, weigh 1g of sodium hypophosphite and place it upstream of the tube furnace, calcine at 300℃ for 3h under nitrogen atmosphere, the heating rate of the tube furnace is 5℃ / min, the nitrogen flow rate is 15mL / min, and then cool down naturally.

[0095] (4) In a 1.5 M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 10 mA·cm⁻¹ -2 Oxidation at a current density of 1.5 h yielded a monolithic electrocatalyst.

[0096] (5) A 1M KOH electrolyte with a BHMF concentration of 100mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.45V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.48T magnetic field. At 1.45V, the hydrogen yield was 63.47% and the FDCA yield was 59.35%. After adding a 0.48T magnetic field, the hydrogen yield was 68.88% and the FDCA yield was 91.77%. Under the same reaction conditions, the reaction time was shortened by 1.52 hours.

[0097] Example 7

[0098] (1) The nickel foam substrate was ultrasonically cleaned in acetone and ethanol for 10 min each, and then dried for later use.

[0099] (2) Prepare a 200mM ferric chloride metal salt solution, immerse the treated foamed nickel in this solution, expose it to air, allow it to corrode naturally at room temperature for 2 hours, remove it, rinse it with deionized water, and air dry it naturally.

[0100] (3) Place the obtained material downstream of the tube furnace, weigh 1g of sodium hypophosphite and place it upstream of the tube furnace, calcine at 400℃ for 1h under nitrogen atmosphere, the heating rate of the tube furnace is 5℃ / min, the nitrogen flow rate is 30mL / min, and then cool down naturally.

[0101] (4) In a 2M NaOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 2mA·cm -2Oxidation at a current density for 3 hours yielded a monolithic electrocatalyst.

[0102] (5) A 1M NaOH electrolyte with a BHMF concentration of 80mM was placed in a membraneless electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 2V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.12T magnetic field. At 2V, the hydrogen yield was 68.62% and the FDCA yield was 53.13%. After adding a 0.12T magnetic field, the hydrogen yield was 76.38% and the FDCA yield was 84.23%. Under the same reaction conditions, the reaction time was shortened by 1.49 hours.

[0103] Example 8

[0104] (1) Clean the iron sheet substrate with acetone and ethanol for 10 min each, and dry it for later use.

[0105] (2) Prepare a 50mM cobalt sulfate metal salt solution, immerse the treated iron sheet in this solution, expose it to air, allow it to corrode naturally at room temperature for 6 hours, remove it, rinse it with deionized water, and air dry it naturally.

[0106] (3) Place the obtained material downstream of the tube furnace, weigh 2g of potassium dihydrogen phosphate and place it upstream of the tube furnace, and calcine at 300℃ for 2h in a helium atmosphere. The heating rate of the tube furnace is 5℃ / min, the helium flow rate is 15mL / min, and the material is allowed to cool naturally.

[0107] (4) In a 0.5 M NaOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 20 mA·cm⁻¹ -2 Oxidation at a current density of 1.5 h yielded a monolithic electrocatalyst.

[0108] (5) A 1M NaOH electrolyte with a BHMF concentration of 100mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.55V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.36T magnetic field. At 1.55V, the hydrogen yield was 60.87% and the FDCA yield was 56.23%. After adding a 0.36T magnetic field, the hydrogen yield was 67.44% and the FDCA yield was 90.37%. Under the same reaction conditions, the reaction time was shortened by 1.79 hours.

[0109] Example 9

[0110] (1) Clean the copper foil substrate with acetone and ethanol for 10 min each, and dry it for later use.

[0111] (2) Prepare a 500mM cobalt chloride metal salt solution, immerse the treated copper foil in this solution, expose it to air, allow it to corrode naturally at room temperature for 0.2h, remove it, rinse it with deionized water, and air dry it naturally.

[0112] (3) Place the obtained material downstream of the tube furnace, weigh 1g of red phosphorus and place it upstream of the tube furnace. Calcinate at 600℃ for 0.5h in an argon atmosphere. The heating rate of the tube furnace is 5℃ / min, the argon flow rate is 50mL / min, and the material is allowed to cool naturally.

[0113] (4) In a 3M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 50 mA·cm⁻¹ -2 Oxidation at a current density of 0.2 h yielded a monolithic electrocatalyst.

[0114] (5) A 3M KOH electrolyte with a BHMF concentration of 400mM was placed in a membraneless electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.6V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under the conditions of no magnetic field and a 0.36T magnetic field applied around the electrodes. At a voltage of 1.6V, the hydrogen yield was 63.85% and the FDCA yield was 53.17%. After adding a 0.36T magnetic field, the hydrogen yield was 69.34% and the FDCA yield was 83.8%. Under the same reaction conditions, the reaction time was shortened by 2.09 hours.

[0115] Example 10

[0116] (1) The foamed copper substrate was ultrasonically cleaned in acetone and ethanol for 10 min each, and then dried for later use.

[0117] (2) Prepare a 250mM nickel sulfate metal salt solution, immerse the treated foamed copper in this solution, expose it to air, allow it to corrode naturally at room temperature for 15 hours, remove it, rinse it with deionized water, and air dry it naturally.

[0118] (3) Place the obtained material downstream of the tube furnace, weigh 1g of sodium dihydrogen phosphate and place it upstream of the tube furnace. Calcinate at 500℃ for 1h under an argon atmosphere. The heating rate of the tube furnace is 5℃ / min, the argon flow rate is 50mL / min, and the material is allowed to cool naturally.

[0119] (4) In a 2M KOH electrolyte, the phosphating material was used as the working electrode, a platinum sheet as the counter electrode, and mercury / mercury oxide as the reference electrode, resulting in a three-electrode system. At 5 mA·cm⁻¹ -2 Oxidation at a current density for 2 hours yielded a monolithic electrocatalyst.

[0120] (5) A 2M KOH electrolyte with a BHMF concentration of 20mM was placed in a membrane-free electrolytic cell. The monolithic electrocatalyst prepared in step (4) was used as the anode and cathode, respectively, to assemble a dual-electrode system. The voltage was set to 1.475V. The yields of hydrogen and FDCA, and the reaction time required for the corresponding yields were tested under conditions of no magnetic field and a 0.24T magnetic field. At 1.475V, the hydrogen yield was 64.55% and the FDCA yield was 53.79%. After adding a 0.24T magnetic field, the hydrogen yield was 69.52% and the FDCA yield was 82.22%. Under the same reaction conditions, the reaction time was shortened by 0.91 hours.

[0121] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A method for magnetic field enhanced electrocatalytic biomass oxidation coupled green hydrogen production, characterized in that, Includes the following steps: S1. Immerse the metal substrate in a metal salt solution that is in contact with air, and obtain a self-supporting precursor through natural corrosion. The metal substrate is selected from any one or more of cobalt, nickel, iron, and copper, and the metal salt in the metal salt solution is selected from any one or more combinations of sulfates, nitrates, and hydrochlorides of transition metals iron, cobalt, and nickel. S2. Phosphate the self-supporting precursor in an inert gas atmosphere; S3. The phosphating-treated self-supporting precursor is subjected to surface electro-oxidation treatment to obtain a magnetic field-responsive monolithic electrocatalyst. S4. Using an integral electrocatalyst as the anode and cathode of the electrocatalytic reaction to form a dual-electrode system, an alkaline solution containing biomass is added to a membrane-free electrolytic cell as the electrolyte. The biomass in the electrolyte is a furan compound selected from at least one of 2,5-furandiethanol, 5-hydroxymethylfurfural, 2,5-dicarboxyfuran, 5-hydroxymethyl-2-furancarboxylic acid, and 5-formyl-2-furancarboxylic acid. S5. Apply a magnetic field around the anode and cathode. The magnetic field lines pass through the electrodes, which are immersed in the electrolyte. The anode undergoes a biomass electrocatalytic oxidation reaction, and the cathode undergoes a hydrogen evolution reaction.

2. The method of magnetic field enhanced electrocatalytic biomass oxidation coupled green hydrogen production according to claim 1, characterized in that, In step S5, the magnetic field strength applied around the electrode is 0.1 to 0.5 T.

3. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic biomass oxidation according to claim 2, characterized in that, In step S5, the electrocatalytic reaction operates at a voltage of 1.6–2.2V for 1–24 hours.

4. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic biomass oxidation according to claim 3, characterized in that, In step S5, the concentration of biomass in the electrolyte is 10–1000 mM.

5. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic oxidation of biomass according to claim 1, characterized in that, In step S1, the form of the metal substrate is selected from any one of metal foam, metal sheet, and metal foil.

6. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic oxidation of biomass according to claim 5, characterized in that, In step S1, the concentration of the metal salt solution is 1–2000 mM, and the natural corrosion time is 0.1–72 h.

7. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic oxidation of biomass according to claim 1, characterized in that, Step S2 specifically includes: placing the phosphorus source upstream of the tubular furnace, placing the self-supporting precursor downstream of the tubular furnace, introducing inert gas into the tubular furnace, heating the tubular furnace to 300-600°C at a heating rate of 1-5°C / min, and holding the temperature for 1-3 hours.

8. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic oxidation of biomass according to claim 7, characterized in that, The inert gas is selected from any one or more of nitrogen, argon, and helium, and the gas volume flow rate of the inert gas is 5 to 100 mL / min.

9. The method of producing green hydrogen by coupling magnetic field enhanced electrocatalytic oxidation of biomass according to claim 1, characterized in that, The step S3 specifically comprises: taking the self-supporting precursor after phosphorization as a working electrode, setting a counter electrode and a reference electrode to form a three-electrode system, immersing the working electrode in an electrolyte to perform constant current oxidation, the current density being 2-50 mA·cm -2 , and the processing time being 0.05-5 h.

10. The method of claim 9, wherein the magnetic field is applied to the electrolytic cell by a magnetic field generator. In step S3, the electrolyte is a sodium hydroxide and / or potassium hydroxide solution with a concentration of 0.1-5M, the counter electrode is selected from any one of platinum sheet, carbon rod, and nickel, and the reference electrode is selected from any one of mercury / mercuric oxide, silver / silver chloride, and saturated calomel.

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