A catalyzer for photoelectric nitrogen fixation of a carrier of a carbon material of a rain mushroom

Abstract

The application discloses a rain mushroom carbon material carrier photoelectric nitrogen fixation catalyst, which comprises a porous carbon material derived from rain mushroom as a carrier, and a metal active component loaded on the carbon material carrier; the metal active component is selected from one or two or more than two metals of iron, cobalt, nickel, molybdenum, ruthenium and iridium in the form of an element, an oxide, a nitride, a phosphide or a sulfide. When the application is implemented, the following advantages are achieved: green raw materials and low cost; the rain mushroom is a natural and renewable carbon source, is widely available and is cheap, and meets the concept of green chemistry and sustainable development; excellent carrier performance; the rain mushroom derived carbon material has a natural multi-level pore structure, a high specific surface area and rich intrinsic heteroatom doping, which not only provides a large number of active sites and reactant transmission channels, but also effectively adjusts the electronic structure of the carbon material, enhances the conductivity and serves as an anchoring point to promote the uniform dispersion and stable loading of the metal active component.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a photoelectric nitrogen fixation catalyst supported on a mushroom carbon material. Background Technology

[0002] Ammonia (NH3) is an irreplaceable bulk industrial raw material, essential to all aspects of industrial, agricultural, and economic development, impacting human survival. The traditional Haber-Bosch process for ammonia production, with its demanding production conditions (high temperature 350-550℃ and high pressure 150-350 atm), consumes vast amounts of global energy and emits significant amounts of CO2, placing immense pressure on the global environment. Photocatalytic technology, utilizing solar energy to produce chemical fuels, can effectively alleviate environmental pollution and energy shortages. Electrocatalytic nitrogen reduction (NRR) technology can fix nitrogen under environmental conditions, representing a sustainable and low-energy-consumption method. However, the high energy required to activate the N≡N bond and the unavoidable competitive hydrogen evolution reaction (HER) prevent significant breakthroughs in ammonia yield and Faradaic efficiency (FE) in NRR. When NRR electrocatalysts are integrated with solar energy, through the injection of photogenerated carriers and bandgap modulation, the N2 adsorption and activation energy barriers can be lowered while suppressing side reactions, thereby achieving a significant improvement in NH3 yield and selectivity. Therefore, developing a photoelectric synergistic nitrogen fixation catalyst that is efficient, stable, and low-cost under mild conditions is of great significance for achieving an environmentally friendly and energy-sustainable ammonia synthesis process.

[0003] Currently, catalysts used for (photo)electro-nitrogen fixation mainly include noble metal-based materials, transition metal compounds, and carbon-based materials. Among them, biomass-derived carbon materials have attracted attention due to their wide availability, low cost, high specific surface area, good conductivity, abundant surface functional groups, and ease of modification. However, the catalytic activity of pure metal-free carbon materials is limited, while conventional methods of supporting metals often suffer from problems such as uneven dispersion of active components, weak binding force with the support, and easy aggregation or loss during the reaction. In addition, the preparation process of many catalysts is complex or uses toxic and harmful reagents, which is not conducive to large-scale production and environmental friendliness.

[0004] *Auricularia auricula-judae* (also known as ground fungus or *Ge Xian Mi*) is a natural, edible cyanobacterium rich in polysaccharides, proteins, cellulose, and various minerals. Its unique microstructure and abundant surface functional groups make it a highly promising precursor for preparing porous, defect-rich, and heteroatom-doped (such as N, O, and S) carbon materials. This structure facilitates electron transport, reactant adsorption, and the anchoring of active sites.

[0005] Therefore, this application proposes a photoelectric nitrogen fixation catalyst supported on a mushroom carbon material. Summary of the Invention

[0006] Therefore, this invention provides a photoelectric nitrogen fixation catalyst supported on a mushroom carbon material, which solves the problems of complex preparation processes or the use of toxic and harmful reagents in many existing catalysts, which are not conducive to large-scale production and environmental friendliness.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A photoelectrophotocatalyst for nitrogen fixation on a *Gnaphalium affine* carbon material support comprises a porous carbon material derived from *Gnaphalium affine* as a support, wherein a metal active component is loaded on the carbon material support; the metal active component is selected from one or more metals selected from iron, cobalt, nickel, molybdenum, ruthenium, and iridium, and is an element, oxide, nitride, phosphide, or sulfide; the mass loading of the metal active component is 0.1 wt%-20 wt% based on the total mass of the catalyst.

[0009] Preferably, the carbon material carrier derived from *Gnaphalium affine* has abundant microporous and mesoporous structures, a specific surface area of ​​300-1500 m² / g, and contains nitrogen, oxygen, and sulfur heteroatoms on its surface, with a total heteroatom content of 1-15 at.

[0010] Preferably, the metal active component is highly dispersed in the form of nanoparticles on the surface and within the pores of the carbon material carrier, and the average particle size of the nanoparticles is 2-50 nm.

[0011] Preferably, the preparation method includes the following steps:

[0012] S1. Preparation of Gynostemma pentaphyllum carbon material carrier: After rehydration, washing, drying and grinding of dried Gynostemma pentaphyllum sample, carbonization was carried out at 400-800℃ for 1-5 hours under an inert atmosphere. The crude carbon obtained was acid washed, water washed until neutral and dried to obtain pure Gynostemma pentaphyllum-derived porous carbon material carrier.

[0013] S2. Loading of the metal active component: The carbon material support obtained in step S1 is dispersed in a solvent, and a metal salt containing the target metal element is added and stirred until uniform.

[0014] S3. Composite and heat treatment: The mixture obtained in step S2 is subjected to hydrothermal reaction, solvothermal reaction or impregnation evaporation treatment, and then heat-treated at 300-700℃ for 1-4 hours in an inert atmosphere or reducing atmosphere to obtain the mushroom carbon material carrier photoelectric nitrogen fixation catalyst.

[0015] Preferably, in step S1, the acid used for pickling is hydrochloric acid or nitric acid with a concentration of 0.05-1.0 M, the washing temperature is room temperature to 80°C, and the washing time is 2-12 hours.

[0016] Preferably, in step S2, the metal salt is a nitrate, chloride, acetate, or acetylacetone salt; and the solvent is water or ethanol.

[0017] Preferably, in step S3, the conditions for the hydrothermal or solvothermal reaction are: temperature 120-200℃, time 6-24 hours; the reducing atmosphere is a mixture of hydrogen and inert gas, or ammonia.

[0018] Preferably, the specific steps of step S1 are as follows:

[0019] S11. Pretreatment: Soak dried samples of *Malus spectabilis* in deionized water until fully rehydrated and expanded. Select individuals with intact shapes and rinse them repeatedly with deionized water to remove surface impurities. Then, dry them in a forced-air dryer at 60-90℃ until constant weight to obtain clean dried *Malus spectabilis*.

[0020] S12. Carbonization: Grind the clean dried mushroom body obtained in step S11 into powder, place it in an inert atmosphere or vacuum environment, and calcine it at 400-800℃ for 1-5 hours to obtain crude carbon material.

[0021] S13. Acid washing and purification: The crude carbon material obtained in step S12 is further ground into fine powder and placed in a 0.05-1.0 M hydrochloric acid or nitric acid solution. It is stirred and washed for 2-12 hours at room temperature to 80°C to remove some ash and soluble inorganic salts. Then it is washed with deionized water until the filtrate is neutral.

[0022] S14. Drying: Dry the acid-washed carbon material at 60-100℃ for 6-24 hours to obtain a pure mushroom-derived porous carbon material carrier.

[0023] The present invention has the following advantages:

[0024] 1. Green and low-cost raw materials: Using natural and renewable mushrooms as carbon source, which are widely available and inexpensive, in line with the concepts of green chemistry and sustainable development;

[0025] 2. Excellent carrier performance: The carbon materials derived from *Gnaphalium affine* have a natural multi-level porous structure, high specific surface area and abundant intrinsic heteroatoms (N, O, S) doping. This not only provides a large number of active sites and reactant transport channels, but the doped atoms can also effectively regulate the electronic structure of the carbon materials, enhance conductivity, and act as anchoring points to promote the uniform dispersion and stable loading of metal active components.

[0026] 3. High catalyst activity and good selectivity: There may be strong electronic interactions (metal-support strong interaction) between highly dispersed metal nanoparticles and carbon supports rich in defects and heteroatoms. This synergistic effect can optimize the adsorption and activation of N2 molecules and reduce the reaction energy barrier. At the same time, under photoelectric synergistic conditions, the participation of photogenerated electrons and holes further promotes charge separation and interfacial reaction kinetics, and helps to suppress competitive hydrogen evolution reaction, thereby significantly improving the yield of ammonia synthesis. Attached Figure Description

[0027] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0028] Fig. 1 Scanning electron microscope (SEM) image of a *Gnaphalium affine* carbon material carrier for a photoelectrophotocatalyst provided in an embodiment of this application.

[0029] Fig. 2 Scanning electron microscope (SEM) image of FeBi alloy loaded on a mushroom carbon material carrier for photoelectrophotocatalysis provided in this application embodiment after Joule heating.

[0030] Fig. 3 This is a flowchart illustrating the preparation process of a photoelectric nitrogen fixation catalyst supported on a mushroom carbon material, as provided in an embodiment of this application. Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are merely for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Technical engineers in the field can make some non-essential improvements and adjustments to the present invention based on the above-described content. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figs. 1-3A photoelectrophotocatalyst for nitrogen fixation on a *Gnaphalium affine* carbon material support is characterized by comprising a porous carbon material derived from *Gnaphalium affine* as a support, wherein a metal active component is loaded on the carbon material support; the metal active component is selected from one or more metals selected from iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), ruthenium (Ru), and iridium (Ir) as an element, oxide, nitride, phosphide, or sulfide; and the mass loading of the metal active component is 0.1 wt%-20 wt% based on the total mass of the catalyst.

[0033] The carbon material carrier derived from *Gnaphalium affine* has abundant microporous and mesoporous structures, with a specific surface area of ​​300-1500 m² / g, and its surface is doped with nitrogen, oxygen, and sulfur heteroatoms, with a total heteroatom content of 1-15 at.

[0034] The active metal component is highly dispersed in the form of nanoparticles on the surface and within the pores of the carbon material carrier, with an average particle size of 2-50 nm.

[0035] A method for preparing a photoelectric nitrogen fixation catalyst supported on a mushroom carbon material includes the following steps:

[0036] S1. Preparation of Gynostemma pentaphyllum carbon material carrier: After rehydration, washing, drying and grinding of dried Gynostemma pentaphyllum sample, carbonization was carried out at 400-800℃ for 1-5 hours under an inert atmosphere. The crude carbon obtained was acid washed, water washed until neutral and dried to obtain pure Gynostemma pentaphyllum-derived porous carbon material carrier.

[0037] S2. Loading of the metal active component: The carbon material support obtained in step S1 is dispersed in a solvent, and a metal salt containing the target metal element is added and stirred until uniform.

[0038] S3. Composite and heat treatment: The mixture obtained in step S2 is subjected to hydrothermal reaction, solvothermal reaction or impregnation evaporation treatment, and then heat-treated at 300-700℃ for 1-4 hours in an inert atmosphere or reducing atmosphere to obtain the mushroom carbon material carrier photoelectric nitrogen fixation catalyst.

[0039] In step S1, the acid used for pickling is hydrochloric acid or nitric acid with a concentration of 0.05-1.0 M, the washing temperature is room temperature to 80°C, and the time is 2-12 hours.

[0040] In step S2, the metal salt is a nitrate, chloride, acetate, or acetylacetone salt; the solvent is water or ethanol.

[0041] In step S3, the conditions for the hydrothermal or solvothermal reaction are: temperature 120-200℃, time 6-24 hours; the reducing atmosphere is a mixture of hydrogen and inert gas, or ammonia.

[0042] The specific steps of step S1 are as follows:

[0043] S11. Pretreatment: Soak dried samples of *Malus spectabilis* in deionized water until fully rehydrated and expanded. Select individuals with intact shapes and rinse them repeatedly with deionized water to remove surface impurities. Then, dry them in a forced-air dryer at 60-90℃ until constant weight to obtain clean dried *Malus spectabilis*.

[0044] S12. Carbonization: Grind the clean dried mushroom body obtained in step S11 into powder, place it in an inert atmosphere or vacuum environment, and calcine it at 400-800℃ for 1-5 hours to obtain crude carbon material.

[0045] S13. Acid washing and purification: The crude carbon material obtained in step S12 is further ground into fine powder and placed in a 0.05-1.0 M hydrochloric acid or nitric acid solution. It is stirred and washed for 2-12 hours at room temperature to 80°C to remove some ash and soluble inorganic salts. Then it is washed with deionized water until the filtrate is neutral.

[0046] S14. Drying: Dry the acid-washed carbon material at 60-100℃ for 6-24 hours to obtain a pure mushroom-derived porous carbon material carrier.

[0047] Example 1: Preparation of Fe-supported mushroom carbon catalyst (Fe@GLCC)

[0048] S1. Carrier Preparation: Take 10g of dried *Lysimachia christinae* sample and soak it in deionized water for 4 hours until fully rehydrated. Select large, intact *Lysimachia christinae* mushrooms and rinse them repeatedly with deionized water 5 times. Place them in a forced-air drying oven at 70℃ and dry for 12 hours until constant weight. Grind the dried *Lysimachia christinae* mushrooms in a mortar for 30 minutes. Place the powder in a tube furnace and calcine it at 500℃ under argon protection at a rate of 5℃ / min for 2 hours. After natural cooling, black crude carbon is obtained. Grind the crude carbon again into a fine powder, add 200 mL of 0.1 mol / L hydrochloric acid solution, and wash with magnetic stirring at 60℃ for 6 hours. Filter and wash repeatedly with deionized water until the pH of the filtrate is approximately 7. Dry the solid in a forced-air drying oven at 70℃ overnight to obtain the *Lysimachia christinae*-derived carbon material carrier (labeled GLCC).

[0049] S2. Metal loading: Weigh 0.1 g of the above GLCC support, disperse it in 30 mL of deionized water, and sonicate for 30 minutes. Weigh 0.052 g of ferric nitrate hexahydrate (Fe(NO3)3·6H2O, corresponding to a theoretical Fe loading of approximately 5 wt%), add it to the above suspension, and stir vigorously at room temperature for 4 hours.

[0050] S3. Heat Treatment: The above mixture was transferred to a 50 mL polytetrafluoroethylene-lined high-pressure reactor and hydrothermally reacted at 120°C for 12 hours. After cooling, the black solid was collected by centrifugation, washed three times each with deionized water and ethanol, and dried at 70°C. The dried solid was then heat-treated at 400°C for 2 hours (heating rate 2°C / min) in an argon / hydrogen (volume ratio 95:5) mixed atmosphere, and allowed to cool naturally to obtain the final catalyst Fe@GLCC.

[0051] Example 2: Preparation of Co-supported mushroom carbon catalyst (Co@GLCC)

[0052] The steps are the same as in Example 1, except that ferric nitrate hexahydrate in S2 is replaced with cobalt nitrate hexahydrate (Co(NO3)3·6H2O), and the amount is adjusted to 0.051 g (corresponding to a theoretical Co loading of about 5 wt%), to obtain the catalyst Co@GLCC.

[0053] Example 3: Preparation of Ru-supported mushroom carbon material catalyst (Ru@GLCC)

[0054] The steps are the same as in Example 1, except that ferric nitrate hexahydrate in S2 is replaced with ruthenium trichloride (RuCl3·xH2O), and the amount is adjusted to 0.025 g (corresponding to a theoretical Ru loading of about 5 wt%), to obtain the catalyst Ru@GLCC.

[0055] Comparative Example 1: Pure Rain-inducing Mushroom Carbon Material (GLCC)

[0056] The GLCC support obtained in step S1 was prepared without metal loading and used directly as a catalyst.

[0057] Comparative Example 2: Fe-supported commercial activated carbon catalyst (Fe@AC)

[0058] The GLCC carrier in Example 1 was replaced with an equal mass of commercial activated carbon (specific surface area 1000 m²). 2 / g), and the other steps are exactly the same as in Example 1 to prepare the Fe@AC catalyst.

[0059] Performance Testing: Photoelectrochemical Nitrogen Reduction Synthesis of Ammonia

[0060] Two mg of each catalyst prepared in the examples and comparative examples were mixed with 20 μL of Nafion solution (5 wt%) and 480 μL of isopropanol, and sonicated for 1 hour to form a uniform catalyst ink. 50 μL of this ink was uniformly drop-coated onto a 1 cm × 2 cm carbon paper and air-dried at room temperature to serve as the working electrode.

[0061] A standard three-electrode system was used in an H-type electrolytic cell for testing. The electrode prepared above was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl (saturated KCl) as the reference electrode. The electrolyte was a 0.1 M Na₂SO₄ solution (pH≈6.8). Before the reaction, high-purity N₂ (99.999%) was continuously bubbled into the electrolyte for at least 30 minutes to remove dissolved oxygen, and the N₂ atmosphere was maintained throughout the reaction. A 300 W xenon lamp (equipped with an AM 1.5G filter) was used as a simulated solar light source to vertically irradiate the working electrode. Under magnetic stirring, a constant electrochemical potential (-0.3 V relative to RHE) was applied for 2 hours to carry out the photoelectrocatalytic reaction.

[0062] The table below shows the photoelectrocatalytic nitrogen reduction performance of the catalysts prepared in each example and comparative example:

[0063]

[0064] Among them: the electrochemical active area was estimated by the double-layer capacitance method; the charge transfer resistance was obtained by fitting the electrochemical impedance spectroscopy at the open-circuit potential.

[0065] The results show that the metal catalyst (especially Fe@GLCC) supported on the mushroom carbon material prepared in this invention exhibits excellent nitrogen fixation activity and selectivity under photoelectric synergistic conditions. Its performance is significantly better than that of pure carbon support without metal support and comparative catalysts supported on the same metal but using commercial supports, demonstrating the unique advantages of mushroom-derived carbon materials as supports and photoelectric synergistic strategies.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier, characterized in that, The catalyst comprises a porous carbon material derived from *Gnaphalium affine* as a support, wherein a metal active component is loaded on the carbon material support; the metal active component is selected from one or more metals selected from iron, cobalt, nickel, molybdenum, ruthenium, and iridium, as well as their elements, oxides, nitrides, phosphides, or sulfides; and the mass loading of the metal active component is 0.1 wt%-20 wt% based on the total mass of the catalyst.

2. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 1, characterized in that, The carbon material carrier derived from *Gnaphalium affine* has abundant microporous and mesoporous structures, with a specific surface area of ​​300-1500 m² / g, and its surface is doped with nitrogen, oxygen, and sulfur heteroatoms, with a total heteroatom content of 1-15 at.

3. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 1, characterized in that, The active metal component is highly dispersed in the form of nanoparticles on the surface and within the pores of the carbon material carrier, with an average particle size of 2-50 nm.

4. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 1, characterized in that, Its preparation method includes the following steps: S1. Preparation of Gynostemma pentaphyllum carbon material carrier: After rehydration, washing, drying and grinding of dried Gynostemma pentaphyllum sample, carbonization was carried out at 400-800℃ for 1-5 hours under an inert atmosphere. The crude carbon obtained was acid washed, water washed until neutral and dried to obtain pure Gynostemma pentaphyllum-derived porous carbon material carrier. S2. Loading of the metal active component: The carbon material support obtained in step S1 is dispersed in a solvent, and a metal salt containing the target metal element is added and stirred until uniformly mixed; S3. Composite and heat treatment: The mixture obtained in step S2 is subjected to hydrothermal reaction, solvothermal reaction or impregnation evaporation treatment, and then heat-treated at 300-700℃ for 1-4 hours in an inert atmosphere or reducing atmosphere to obtain the mushroom carbon material carrier photoelectric nitrogen fixation catalyst.

5. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 4, characterized in that, In step S1, the acid used for pickling is hydrochloric acid or nitric acid with a concentration of 0.05-1.0 M, the washing temperature is room temperature to 80°C, and the time is 2-12 hours.

6. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 4, characterized in that, In step S2, the metal salt is a nitrate, chloride, acetate, or acetylacetone salt; the solvent is water or ethanol.

7. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 4, characterized in that, In step S3, the conditions for the hydrothermal or solvothermal reaction are: temperature 120-200℃, time 6-24 hours; the reducing atmosphere is a mixture of hydrogen and inert gas, or ammonia.

8. The photoelectrophotocatalyst for nitrogen fixation on a mushroom carbon material carrier according to claim 4, characterized in that, The specific steps of step S1 are as follows: S11. Pretreatment: Soak dried samples of *Malus spectabilis* in deionized water until fully rehydrated and expanded. Select individuals with intact shapes and rinse them repeatedly with deionized water to remove surface impurities. Then, dry them in a forced-air dryer at 60-90℃ until constant weight to obtain clean dried *Malus spectabilis*. S12. Carbonization: Grind the clean dried mushroom body obtained in step S11 into powder, place it in an inert atmosphere or vacuum environment, and calcine it at 400-800℃ for 1-5 hours to obtain crude carbon material. S13. Acid washing and purification: The crude carbon material obtained in step S12 is further ground into fine powder and placed in a 0.05-1.0 mol / L hydrochloric acid or nitric acid solution. It is stirred and washed for 2-12 hours at room temperature to 80°C to remove some ash and soluble inorganic salts. Then it is washed with deionized water until the filtrate is neutral. S14. Drying: Dry the acid-washed carbon material at 60-100℃ for 6-24 hours to obtain a pure mushroom-derived porous carbon material carrier.

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