Preparation method of biomass carbon quantum dot cathode material and application thereof in microbial electrolysis cell

Abstract

The application discloses a preparation method of a biomass carbon quantum dot cathode material and application of the biomass carbon quantum dot cathode material in a microbial electrolysis cell, and the preparation method comprises the following steps: modifying cellulose by using urea, and preparing nitrogen-doped biomass carbon quantum dots through a water solution method; and synthesizing biomass carbon quantum dot loaded nano NiO by using nickel nitrate through a precipitation method and heat treatment, and taking the biomass carbon quantum dot loaded nano NiO as active material of a cathode of the microbial electrolysis cell. The nitrogen-doped carbon quantum dots have more catalytic sites and stronger conductivity, are beneficial to electron migration and conduction, promote combination of catalytic hydrogen protons and electrons to generate hydrogen, and thus improve hydrogen production rate and hydrogen production efficiency of the MEC microbial electrolysis cell, and have a wide application prospect in hydrogen production of the microbial electrolysis cell.

Description

Technical Field

[0001] This invention relates to the field of cathode materials technology for microbial electrolysis cells, and particularly to a method for preparing biomass carbon quantum dot cathode materials and their application in microbial electrolysis cells. Background Technology

[0002] The overexploitation and use of fossil fuels has led to a severe energy crisis and environmental pollution, making the development of green and clean energy an urgent priority. Hydrogen energy, with its advantages of being environmentally friendly, pollution-free, and having high combustion performance, is an ideal clean energy source. Currently, industrial hydrogen production methods mainly include methane reforming, electrochemical hydrogen production, and photocatalytic hydrogen production. Microbial electrolysis (MEC) reactors utilize microorganisms at the anode of a MEC reactor to degrade organic matter, producing hydrogen protons and electrons. These protons and electrons then migrate to the cathode, where, under the action of a cathode catalyst, they combine to produce hydrogen gas. This technology represents a highly promising approach to hydrogen production.

[0003] The electrochemical performance and activation energy of the hydrogen evolution reaction of the cathode material in a MEC reactor have a significant impact on the hydrogen production efficiency of MEC. For example, the literature "Preparation of Nano-NiO-Y Composite Cathode Material and Catalytic Hydrogen Production Performance in Microbial Electrolyzers" reports the preparation of nano-NiO-Y composite material by impregnating nano-Y molecular sieves with an aqueous solution of nickel salt precursor and then calcining it. This composite material is expected to replace precious metal materials as hydrogen evolution cathode material in MEC microbial electrolyzers; however, it suffers from poor hydrogen production rate and efficiency.

[0004] Therefore, it is necessary to explore the preparation methods of biomass carbon quantum dot cathode materials and their application in microbial electrolysis cells to solve the above-mentioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing biomass carbon quantum dot cathode materials and their application in microbial electrolyzers. The invention aims to synthesize biomass carbon quantum dot-supported nano-NiO as an active cathode material for microbial electrolyzers, which exhibits excellent hydrogen production efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a biomass carbon quantum dot cathode material includes the following steps:

[0008] (1) Epoxidized cellulose was added to dimethyl sulfoxide, stirred evenly, and then urea was added. After heating and reacting, reaction solution A was obtained. Organic solvent was added to reaction solution A to precipitate the precipitate. After filtration and washing, urea-modified cellulose was obtained.

[0009] (2) The urea-modified cellulose in step (1) is added to distilled water and ultrasonically dispersed to form a modified cellulose dispersion; the modified cellulose dispersion is placed in a hydrothermal reactor for hydrothermal reaction, and after the reaction is completed, it is centrifuged to separate the upper liquid and dialyze it in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0010] (3) The nitrogen-doped biomass carbon quantum dots from step (2) are added to distilled water and ultrasonically dispersed to obtain a nitrogen-doped biomass carbon quantum dot dispersion; nickel nitrate is added to the nitrogen-doped biomass carbon quantum dot dispersion, and an alkaline solution is added dropwise to adjust the pH to alkaline, and the reaction is stirred; after the reaction is completed, the product is obtained by filtration and washing; the product is placed in a resistance furnace for heat treatment to obtain biomass carbon quantum dot-loaded nano-NiO;

[0011] (4) Biomass carbon quantum dot-loaded nano-NiO is added to ethanol and ultrasonically dispersed to obtain a biomass carbon quantum dot-loaded nano-NiO dispersion; Nafion solution is added dropwise to the biomass carbon quantum dot-loaded nano-NiO dispersion to obtain a mixture B; the mixture B is coated on the surface of carbon paper and dried to obtain a biomass carbon quantum dot cathode material.

[0012] Preferably, the mass ratio of epoxidized cellulose to urea in step (1) is 1:3-6; the mass concentration of epoxidized cellulose in dimethyl sulfoxide is (10-50) g / L; and the organic solvent is ethanol.

[0013] Preferably, the heating reaction in step (1) is carried out at 60-85 °C for 6-18 h; the washing is carried out using an ethanol solution.

[0014] Preferably, the hydrothermal reaction in step (2) is carried out at 200-230 °C for 10-20 h.

[0015] Preferably, the mass ratio of nitrogen-doped biomass carbon quantum dots to nickel nitrate in step (3) is 1:3-12.

[0016] Preferably, the alkaline solution in step (3) is sodium hydroxide, the pH value is 9-10, the stirring reaction time is 2-4 h, the washing is washing with deionized water, and the heat treatment is treatment at 250-300 ℃ for 2-3 h.

[0017] Preferably, the mass concentration of biomass carbon quantum dot-supported nano-NiO in Nafion solution in step (4) is 15-80 g / L.

[0018] Preferably, the obtained biomass carbon quantum dot cathode material is used in a microbial electrolyzer to produce hydrogen in the reactor of the microbial electrolyzer.

[0019] Preferably, the hydrogen production method using a microbial electrolysis cell reactor includes the following steps:

[0020] A nutrient solution containing glucose, mineral element compounds, and phosphate buffer solution in a mass ratio of (1-20):(0.2-5):100 is added to a microbial electrolysis reactor. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated and mature electroactive microorganisms; the cathode is the biomass carbon quantum dot cathode material. A voltage of 0.5-0.8 V is applied to both the anode and cathode. The microbial electrolysis reactor operates for 12-24 hours per cycle. After each cycle, 50-100 mL of nutrient solution is replaced to produce hydrogen in the microbial electrolysis reactor.

[0021] Preferably, the mineral element compound is one or any combination of sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, manganese sulfate, ferric sulfate, and zinc sulfate.

[0022] The beneficial effects of this invention are as follows:

[0023] This invention utilizes epichlorohydrin to epoxidize cellulose, followed by a ring-opening reaction between the epoxy groups and the amino groups of urea to obtain urea-modified cellulose. Nitrogen-doped biomass carbon quantum dots are prepared via a water-soluble method. Nickel nitrate is then synthesized with biomass carbon quantum dots through precipitation and heat treatment to obtain biomass carbon quantum dot-supported nano-NiO, which serves as the active material for the cathode of a MEC (microbial electrolyzer). The nitrogen-doped carbon quantum dots have more catalytic sites and stronger conductivity, which is beneficial for electron migration and conduction, promoting the catalytic combination of hydrogen protons and electrons to produce hydrogen gas. This improves the hydrogen production rate and efficiency of the MEC microbial electrolyzer, showing broad application prospects in hydrogen production through microbial electrolysis. Detailed Implementation

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] The following is a method for preparing epoxidized cellulose: Microcrystalline cellulose was added to a 14% sodium hydroxide solution and soaked and activated for 24 h. Then, the activated microcrystalline cellulose was added to distilled water and stirred to swell. Epichlorohydrin and a 30% sodium hydroxide solution were added dropwise, and the mixture was stirred and reacted at 40 °C for 2.5 h to obtain epoxidized cellulose.

[0026] Example 1

[0027] The preparation method of the biomass carbon quantum dot cathode material and the method of using the biomass carbon quantum dot cathode material to produce hydrogen in the reactor of a microbial electrolysis cell provided in Example 1 are as follows:

[0028] (1) 100 parts by weight of epoxidized cellulose were added to dimethyl sulfoxide to prepare a solution with a mass concentration of 10 g / L. After stirring evenly, 300 parts by weight of urea were added and heated to 60°C for 12 h. After the reaction, ethanol solvent was added to precipitate the precipitate. After filtering the solvent, the urea-modified cellulose was obtained by washing with ethanol.

[0029] (2) Urea-modified cellulose was added to distilled water and ultrasonically dispersed. The dispersion was placed in a hydrothermal reactor and hydrothermally reacted at 200 °C for 20 h. After the reaction was completed, the solution was centrifuged to remove insoluble solids. The upper liquid was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0030] (3) 100 parts by weight of biomass carbon quantum dots were added to distilled water for ultrasonic dispersion. 300 parts by weight of nickel nitrate were added to the dispersion, and sodium hydroxide was added dropwise to adjust the pH of the solution to 10. The reaction was stirred for 3 h. After the reaction was completed, the solvent was filtered and the product was washed with deionized water. The product was placed in a resistance furnace and heat-treated at 280 °C for 2 h to obtain biomass carbon quantum dot-supported nano-NiO.

[0031] (4) Add biomass carbon quantum dot-loaded nano-NiO to ethanol, disperse it by ultrasonication, and then add Nafion solution dropwise. Control the mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution to 20 g / L. Then coat the ethanol solution onto the surface of carbon paper and dry it to obtain biomass carbon quantum dot cathode material.

[0032] (5) Add the nutrient solution of glucose, sodium chloride and phosphate buffer solution with a mass ratio of 1:0.2:100 to the microbial electrolysis reactor. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated electroactive microorganisms. The cathode is a biomass carbon quantum dot cathode material. Then, apply a voltage of 0.5 V to the two ends of the electrode. The running time of each cycle is 24 h. After each cycle, replace 50 mL of nutrient solution to produce hydrogen in the MEC reactor.

[0033] Example 2

[0034] The preparation method of the biomass carbon quantum dot cathode material and the method of using the biomass carbon quantum dot cathode material to produce hydrogen in the reactor of a microbial electrolysis cell provided in Example 2 are as follows:

[0035] (1) 100 parts by weight of epoxidized cellulose were added to dimethyl sulfoxide to prepare a solution with a mass concentration of 20 g / L. After stirring evenly, 400 parts by weight of urea were added and heated to 60°C for 18 h. After the reaction, ethanol solvent was added to precipitate the precipitate. After filtering the solvent, the urea-modified cellulose was obtained by washing with ethanol.

[0036] (2) Urea-modified cellulose was added to distilled water and ultrasonically dispersed. The dispersion was placed in a hydrothermal reactor and hydrothermally reacted at 220 °C for 20 h. After the reaction was completed, the solution was centrifuged to remove insoluble solids. The upper liquid was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0037] (3) 100 parts by weight of biomass carbon quantum dots were added to distilled water for ultrasonic dispersion. 500 parts by weight of nickel nitrate were added to the dispersion, and sodium hydroxide was added dropwise to adjust the pH of the solution to 9. The reaction was stirred for 2 h. After the reaction was completed, the solvent was filtered and the product was washed with deionized water. The product was placed in a resistance furnace and heat-treated at 300 °C for 3 h to obtain biomass carbon quantum dot-supported nano-NiO.

[0038] (4) Add biomass carbon quantum dot-loaded nano-NiO to ethanol, disperse it by ultrasonication, and then add Nafion solution dropwise. Control the mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution to 15 g / L. Then coat the ethanol solution onto the surface of carbon paper and dry it to obtain biomass carbon quantum dot cathode material.

[0039] (5) Add a nutrient solution of glucose, mineral element compound and phosphate buffer solution in a ratio of 10:3:100 to the microbial electrolysis reactor. The mineral element compound is potassium chloride and calcium chloride. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated electroactive microorganisms. The cathode is a biomass carbon quantum dot cathode material. Then, apply a voltage of 0.5 V to the two ends of the electrode. The running time of each cycle is 12 h. After each cycle, replace 100 mL of nutrient solution to produce hydrogen in the MEC reactor.

[0040] Example 3

[0041] The preparation method of the biomass carbon quantum dot cathode material and the method of using the biomass carbon quantum dot cathode material to produce hydrogen in the reactor of a microbial electrolysis cell provided in Example 3 are as follows:

[0042] (1) 100 parts by weight of epoxidized cellulose were added to dimethyl sulfoxide to prepare a solution with a mass concentration of 50 g / L. After stirring evenly, 400 parts by weight of urea were added and heated to 85°C for 12 h. After the reaction, ethanol solvent was added to precipitate the precipitate. After filtering the solvent, the cellulose was washed with ethanol to obtain urea-modified cellulose.

[0043] (2) Urea-modified cellulose was added to distilled water and ultrasonically dispersed. The dispersion was placed in a hydrothermal reactor and hydrothermally reacted at 200 °C for 20 h. After the reaction was completed, the solution was centrifuged to remove insoluble solids. The upper liquid was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0044] (3) 100 parts by weight of biomass carbon quantum dots were added to distilled water for ultrasonic dispersion. 700 parts by weight of nickel nitrate were added to the dispersion, and sodium hydroxide was added dropwise to adjust the pH of the solution to 10. The reaction was stirred for 2 h. After the reaction was completed, the solvent was filtered and the product was washed with deionized water. The product was placed in a resistance furnace and heat-treated at 250 °C for 3 h to obtain biomass carbon quantum dot-supported nano-NiO.

[0045] (4) Add biomass carbon quantum dot-loaded nano-NiO to ethanol, disperse it by ultrasonication, and then add Nafion solution dropwise. Control the mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution to 50 g / L. Then coat the ethanol solution onto the surface of carbon paper and dry it to obtain biomass carbon quantum dot cathode material.

[0046] (5) Add a nutrient solution of glucose, mineral element compound and phosphate buffer solution in a mass ratio of 20:5:100 to the microbial electrolysis reactor. The mineral element compound is ammonium chloride and magnesium sulfate. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated electroactive microorganisms. The cathode is a biomass carbon quantum dot cathode material. Then, apply a voltage of 0.6 V to the two ends of the electrode. The running time of each cycle is 12 h. After each cycle, replace 100 mL of nutrient solution to produce hydrogen in the MEC reactor.

[0047] Example 4

[0048] The preparation method of the biomass carbon quantum dot cathode material and the method of using the biomass carbon quantum dot cathode material to produce hydrogen in the reactor of a microbial electrolysis cell provided in Example 4 are as follows:

[0049] (1) 100 parts by weight of epoxidized cellulose were added to dimethyl sulfoxide to prepare a solution with a mass concentration of 30 g / L. After stirring evenly, 500 parts by weight of urea were added and heated to 75°C for 12 h. After the reaction, ethanol solvent was added to precipitate the precipitate. After filtering the solvent, the urea-modified cellulose was obtained by washing with ethanol.

[0050] (2) Urea-modified cellulose was added to distilled water and ultrasonically dispersed. The dispersion was placed in a hydrothermal reactor and hydrothermally reacted at 220 °C for 12 h. After the reaction was completed, the solution was centrifuged to remove insoluble solids. The upper liquid was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0051] (3) 100 parts by weight of biomass carbon quantum dots were added to distilled water for ultrasonic dispersion. 1000 parts by weight of nickel nitrate were added to the dispersion, and sodium hydroxide was added dropwise to adjust the pH of the solution to 10. The reaction was stirred for 3 h. After the reaction was completed, the solvent was filtered and the product was washed with deionized water. The product was placed in a resistance furnace and heat-treated at 280 °C for 2 h to obtain biomass carbon quantum dot-supported nano-NiO.

[0052] (4) Biomass carbon quantum dot-loaded nano-NiO was added to ethanol, ultrasonically dispersed, and then Nafion solution was added dropwise. The mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution was controlled to be 80 g / L. Then, the ethanol solution was coated on the surface of carbon paper and dried to obtain biomass carbon quantum dot cathode material.

[0053] (5) Add a nutrient solution of glucose, mineral element compound and phosphate buffer solution in a mass ratio of 15:4:100 to the microbial electrolysis reactor. The mineral element compound is a mixture of manganese sulfate and ferric sulfate. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated electroactive microorganisms. The cathode is a biomass carbon quantum dot cathode material. Then, apply an external voltage of 0.8 V to the two ends of the electrode. The running time of each cycle is 18 h. After each cycle, replace 50 mL of nutrient solution to produce hydrogen in the MEC reactor.

[0054] Example 5

[0055] The preparation method of the biomass carbon quantum dot cathode material and the method of using the biomass carbon quantum dot cathode material to produce hydrogen in the reactor of a microbial electrolysis cell provided in Example 5 are as follows:

[0056] (1) 100 parts by weight of epoxidized cellulose were added to dimethyl sulfoxide to prepare a solution with a mass concentration of 50 g / L. After stirring evenly, 600 parts by weight of urea were added and heated to 75°C for 6 h. After the reaction, ethanol solvent was added to precipitate the precipitate. After filtering the solvent, the cellulose was washed with ethanol to obtain urea-modified cellulose.

[0057] (2) Urea-modified cellulose was added to distilled water and ultrasonically dispersed. The dispersion was placed in a hydrothermal reactor and hydrothermally reacted at 230 °C for 10 h. After the reaction, the solution was centrifuged to remove insoluble solids. The upper liquid was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots.

[0058] (3) 100 parts by weight of biomass carbon quantum dots were added to distilled water for ultrasonic dispersion. 1200 parts by weight of nickel nitrate were added to the dispersion, and sodium hydroxide was added dropwise to adjust the pH of the solution to 9. The reaction was stirred for 4 h. After the reaction was completed, the solvent was filtered and the product was washed with deionized water. The product was placed in a resistance furnace and heat-treated at 300 °C for 2.5 h to obtain biomass carbon quantum dot-supported nano-NiO.

[0059] (4) Add biomass carbon quantum dot-loaded nano-NiO to ethanol, disperse it by ultrasonication, and then add Nafion solution dropwise. Control the mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution to 40 g / L. Then coat the ethanol solution onto the surface of carbon paper and dry it to obtain biomass carbon quantum dot cathode material.

[0060] (5) A nutrient solution of glucose, mineral element compound and phosphate buffer solution with a mass ratio of 5:0.9:100 is added to the microbial electrolysis reactor. The mineral element compound is a mixture of sodium chloride, potassium chloride and zinc sulfate. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated electroactive microorganisms. The cathode is a biomass carbon quantum dot cathode material. Then, a voltage of 0.8 V is applied to both ends of the electrode. The running time of each cycle is 12 h. After each cycle, 80 mL of nutrient solution is replaced to produce hydrogen in the MEC reactor.

[0061] Experimental Example 1

[0062] The maximum current density of the biomass carbon quantum dot cathode materials prepared in Examples 1-5 was tested, and the results are shown in Table 1. As shown in Table 1, the maximum current density of the biomass carbon quantum dot cathode material prepared in this invention reaches 49.2 A / m. 3 .

[0063] The hydrogen production rate of the biomass carbon quantum dot cathode materials prepared in Examples 1-5 was tested, and the results are shown in Table 1. As shown in Table 1, the hydrogen production rate of the biomass carbon quantum dot cathode material prepared in this invention reaches 0.202 m³ / s. 3 -H2 / m 3 ·d.

[0064] Table 1 Maximum current density and hydrogen production rate of biomass carbon quantum dot cathode materials

[0065]

[0066] In summary, the biomass carbon quantum dot-supported nano-NiO of this invention, as the active material of the cathode of the MEC microbial electrolyzer, has more catalytic sites and stronger conductivity, which is conducive to electron migration and conduction, promotes the catalytic combination of hydrogen protons and electrons to produce hydrogen, thereby improving the hydrogen production rate and efficiency of the MEC microbial electrolyzer.

[0067] The specific embodiments of the invention have been described in detail above, but these are merely examples, and the invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of this invention. Therefore, all equivalent transformations, modifications, and improvements made without departing from the spirit and principles of this invention should be included within the scope of this invention.

Claims

1. A method for preparing a biomass carbon quantum dot cathode material, characterized in that, Includes the following steps: (1) Epoxidized cellulose was added to dimethyl sulfoxide, stirred evenly, and then urea was added. After heating and reacting, reaction solution A was obtained. Organic solvent was added to reaction solution A to precipitate the precipitate. After filtration and washing, urea-modified cellulose was obtained. (2) The urea-modified cellulose from step (1) is added to distilled water and ultrasonically dispersed to form a modified cellulose dispersion; The modified cellulose dispersion was placed in a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, it was centrifuged, the supernatant was collected and dialyzed in a dialysis bag to obtain nitrogen-doped biomass carbon quantum dots. (3) Add the nitrogen-doped biomass carbon quantum dots from step (2) to distilled water and ultrasonically disperse them to obtain a nitrogen-doped biomass carbon quantum dot dispersion. Nickel nitrate was added to a nitrogen-doped biomass carbon quantum dot dispersion, and an alkaline solution was added dropwise to adjust the pH to alkaline. The mixture was stirred and reacted. After the reaction was completed, the mixture was filtered and washed to obtain the reaction product. The reaction product was then placed in a resistance furnace for heat treatment to obtain biomass carbon quantum dot-supported nano-NiO. (4) Biomass carbon quantum dot-loaded nano-NiO is added to ethanol and ultrasonically dispersed to obtain a biomass carbon quantum dot-loaded nano-NiO dispersion; Nafion solution is added dropwise to the biomass carbon quantum dot-loaded nano-NiO dispersion to obtain a mixture B; the mixture B is coated on the surface of carbon paper and dried to obtain a biomass carbon quantum dot cathode material.

2. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The mass ratio of epoxidized cellulose to urea in step (1) is 1:3-6; the mass concentration of epoxidized cellulose in dimethyl sulfoxide is 10-50 g / L; and the organic solvent is ethanol.

3. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The heating reaction in step (1) is carried out at 60-85 °C for 6-18 h; the washing is carried out using an ethanol solution.

4. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The hydrothermal reaction described in step (2) is carried out at 200-230 °C for 10-20 h.

5. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The mass ratio of nitrogen-doped biomass carbon quantum dots to nickel nitrate in step (3) is 1:3-12.

6. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The alkaline solution in step (3) is sodium hydroxide, the pH value is 9-10; the stirring reaction time is 2-4 h; the washing is done with deionized water; the heat treatment is done at 250-300 ℃ for 2-3 h.

7. The method for preparing a biomass carbon quantum dot cathode material as described in claim 1, characterized in that, The mass concentration of biomass carbon quantum dot-loaded nano-NiO in Nafion solution in step (4) is 15-80 g / L.

8. The application of a biomass carbon quantum dot cathode material prepared by the method of any one of claims 1-7 in a microbial electrolysis cell, wherein the biomass carbon quantum dot cathode material is used to produce hydrogen in the reactor of the microbial electrolysis cell.

9. The application of the biomass carbon quantum dot cathode material obtained by the preparation method of biomass carbon quantum dot cathode material as described in claim 8 in a microbial electrolysis cell, characterized in that, A method for producing hydrogen using a microbial electrolysis reactor includes the following steps: A nutrient solution containing glucose, mineral element compounds, and phosphate buffer solution in a mass ratio of (1-20):(0.2-5):100 is added to a microbial electrolysis reactor. The anode of the microbial electrolysis reactor is a circular carbon felt coated with domesticated and mature electroactive microorganisms; the cathode is the biomass carbon quantum dot cathode material. A voltage of 0.5-0.8 V is applied to both the anode and cathode. The microbial electrolysis reactor operates for 12-24 hours per cycle. After each cycle, 50-100 mL of nutrient solution is replaced to produce hydrogen in the microbial electrolysis reactor.

10. The application of the biomass carbon quantum dot cathode material obtained by the preparation method of biomass carbon quantum dot cathode material as described in claim 9 in a microbial electrolysis cell, characterized in that, The mineral element compound is one or more of sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, manganese sulfate, ferric sulfate, and zinc sulfate.

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