Two-dimensional material loaded graphene quantum dot catalyst as well as preparation method and application thereof
By loading graphene quantum dots on CoFe-LDH to form a CoFe-LDH@N-GQDs/NF composite catalyst, the problems of easy stacking and poor conductivity of LDHs are solved, and the electrocatalytic hydrogen evolution performance and stability are improved.
Patent Information
- Application Number
- CN202510707334.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-08-01
AI Technical Summary
Existing layered bimetallic hydroxides (LDHs) are easy to stack in the field of electrocatalytics, resulting in uneven distribution of active sites and poor conductivity, limiting their application; graphene quantum dots (GQDs) are less researched in combination with two-dimensional materials, and have poor performance.
The graphene quantum dots are loaded on CoFe-LDH by hydrothermal method to form a CoFe-LDH@N-GQDs/NF composite catalyst. The graphene quantum dots provide additional catalytically active sites, regulate local electronic structure, enhance conductivity, and prevent aggregation.
The electrocatalytic hydrogen evolution performance and stability were significantly improved, the overpotential was reduced to 95mV, and there was no significant change in continuous test for 100 hours, showing excellent conductivity and catalytic activity.
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Figure CN120400893A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrocatalytic materials, and particularly to a two-dimensional material supported graphene quantum dot catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] Hydrogen energy is a sustainable clean energy and is considered one of the most potential alternatives to fossil fuels. Producing green hydrogen by electrolyzing water is a large-scale hydrogen production method with both economic and environmental sustainability. The current most effective electrocatalytic hydrogen evolution catalyst is a platinum-based catalyst, but its resource scarcity and high cost limit its large-scale application. Therefore, developing efficient and stable non-precious metal catalysts is crucial for promoting the technology and application of electrolytic water hydrogen production.
[0003] Transition metals have been widely studied as efficient hydrogen evolution catalysts due to their rich reserves, low cost, and excellent catalytic activity. Among them, layered double metal hydroxides (LDHs) have been widely used in the field of electrocatalysis due to their reasonable specific surface area, abundant active sites, strong redox activity, and environmental friendliness. However, the layered structure of LDHs is prone to stacking, which is not conducive to the distribution of active sites and hinders the adsorption and transport of surface ions. In addition, the poor conductivity of LDHs limits its application in electrocatalysis.
[0004] Graphene quantum dots (GQDs) combine the advantages of graphene nanosheets and quantum dots, showing characteristics such as a large specific surface area, excellent conductivity, easy doping, and rich functional groups, and have great application prospects in the field of electrocatalysis. The heteroatom doping of GQDs can induce changes in structure and local electrons, thereby affecting their conductivity and catalytic performance. However, there is currently little research on two-dimensional material supported graphene quantum dot catalysts, and their performance is poor. To solve the above problems, the present invention provides a two-dimensional material supported graphene quantum dot catalyst, a preparation method thereof, and an application thereof. Summary of the Invention
[0005] The present invention discloses a two-dimensional material supported graphene quantum dot catalyst, a preparation method thereof, and an application thereof. To solve the above problems, the introduction of graphene dots provides additional catalytic active sites, which have a synergistic effect with the two-dimensional material to regulate the local electronic structure, improve the charge transfer kinetics, and enhance the conductivity; while the two-dimensional material disperses the graphene quantum dots to prevent aggregation. The synergistic effect between graphene quantum dots and two-dimensional materials significantly improves the performance and stability of electrocatalytic hydrogen evolution.
[0006] The present invention discloses a preparation method of a two-dimensional material supported graphene quantum dot catalyst, comprising the following steps:
[0007] S1. Preparation of graphene quantum dots;
[0008] S2. Preparation of cobalt-iron layered double hydroxide: Ultrasonically clean nickel foam with 0.5M - 2M hydrochloric acid, ethanol, and water respectively. Put the cleaned nickel foam into a hydrothermal reaction kettle. Dissolve iron source, cobalt source, complexing agent, and urea in deionized water, stir evenly and transfer it to the reaction kettle containing nickel foam, and react at 110°C - 150°C for 6 - 15 hours. After the reaction ends, take out the nickel foam with grown CoFe-LDH and wash it with deionized water and ethanol.
[0009] S3. Preparation of CoFe-LDH@N-GQDs / NF composite catalyst: Dissolve the graphene quantum dots prepared in S1 in deionized water to prepare a graphene quantum dot solution. Add the graphene quantum dot solution and the nickel foam with grown CoFe-LDH into the reaction kettle, and react at 140°C - 160°C for 2 - 5 hours. Finally, obtain the CoFe-LDH@N-GQDs / NF composite catalyst after washing and drying.
[0010] Preferably, in step S1, the preparation of graphene quantum dots specifically includes the following steps: Dissolve carbon source and nitrogen source reagent or sulfur source reagent in a solvent, stir evenly and transfer it to the reaction kettle, and react at 160°C - 200°C for 6 - 20 hours. After the reaction ends, take out the product and centrifuge it, and take the supernatant for dialysis and freeze-drying to obtain graphene quantum dots. The molar ratio of carbon source to nitrogen source reagent or sulfur source reagent is 1:(0.5 - 2); where the carbon source is citric acid, the nitrogen source reagent or sulfur source reagent is thiourea, and the solvent is deionized water.
[0011] Preferably, in step S1, the carbon source can also be small molecule organic acids such as ascorbic acid and tartaric acid, small molecule sugars such as glucose, fructose, and sucrose, and aromatic compounds such as aniline, phenylenediamine, hydroquinone, benzoic acid, and salicylic acid; the nitrogen source reagent can also be any one of urea, ethylenediamine, lysine, glutamic acid, ammonia water, and hydrazine; the sulfur source reagent can also be any one of sodium thiosulfate, cysteine, or thioglycolic acid.
[0012] Preferably, in step S2, the iron source is cobalt nitrate nonahydrate, the cobalt source is cobalt nitrate hexahydrate, and the complexing agent is citric acid.
[0013] Preferably, in step S2, the iron source can also be any one of ferrous sulfate and ferric chloride hexahydrate; the cobalt source can also be any one of cobalt sulfate heptahydrate, cobalt chloride hexahydrate, cobalt sulfate heptahydrate, and cobalt chloride hexahydrate; the complexing agent can also be sodium citrate or ammonium fluoride.
[0014] Preferably, in step S2, the molar ratio of cobalt source, iron source, complexing agent, and urea is 1:(0.5 - 2):(0.5 - 2):(1 - 5).
[0015] Preferably, in step S3, the concentration of the graphene quantum dot solution is 0.1-10 mg / mL.
[0016] Preferably, in step S3, the mass ratio of the graphene quantum dot solution to the nickel foam grown with CoFe-LDH is 1:(0.08-0.24).
[0017] The present invention also provides a two-dimensional material-supported graphene quantum dot catalyst prepared by the above preparation method, and the two-dimensional material-supported graphene quantum dot catalyst is used in the fields of electrocatalytic hydrogen evolution and electrocatalytic oxygen evolution.
[0018] Therefore, the present invention provides a two-dimensional material-supported graphene quantum dot catalyst, a preparation method and an application, which have the following beneficial effects:
[0019] (1) The present invention provides a method for improving the electrocatalytic hydrogen evolution performance of layered materials through graphene quantum dots.
[0020] (2) The two-dimensional material-supported graphene quantum dot catalyst prepared by the present invention is synthesized by a hydrothermal method, and has the characteristics of simple synthesis conditions and cheap and easily available raw materials.
[0021] (3) The CoFe-LDH silver ear-shaped layered structure exposes more active sites, and at the same time plays a role in dispersing the graphene quantum dots, preventing the aggregation of quantum dots. The addition of graphene quantum dots not only introduces more active sites, improves the adsorption of reaction intermediates, but also adjusts the electronic structure of the catalyst, enhances the conductivity, thereby enhancing the charge transfer and improving the performance of the catalyst. The CoFe-LDH@N-GQDs / NF composite catalyst is used for electrolytic water hydrogen evolution. The overpotential of the catalyst at a current density of 10 mA / cm 2 is only 95 mV, and it still has stable performance after continuous testing for 100 hours. Description of the Drawings
[0022] Figure 1 It is a scanning electron microscope (SEM) image of the two-dimensional material-supported graphene quantum dot catalyst prepared in Example 1 of the present invention.
[0023] Figure 2 It is an X-ray diffraction pattern (XRD) of the two-dimensional material-supported graphene quantum dot catalyst prepared in Example 1 of the present invention.
[0024] Figure 3 It is a linear sweep voltammetry curve of the two-dimensional material-supported graphene quantum dot catalyst prepared in Example 1 of the present invention for electrolytic water hydrogen evolution.
[0025] Figure 4The time-current curve of the two-dimensional material-supported graphene quantum dot catalyst prepared in Example 1 of the present invention for hydrogen evolution by electrolysis of water. Detailed implementation manners
[0026] The present invention will be further described below through specific examples, but it should be understood that these examples are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.
[0027] The present invention discloses a preparation method of a two-dimensional material-supported graphene quantum dot catalyst, comprising the following steps:
[0028] S1. Preparation of graphene quantum dots: Dissolve a carbon source and a nitrogen source reagent or a sulfur source reagent in a solvent, stir evenly and transfer to a reaction kettle, and react at 160°C to 200°C for 6 to 20 hours; after the reaction is completed, take out the product and centrifuge, and take the supernatant for dialysis and freeze-drying to obtain graphene quantum dots; the molar ratio of the carbon source to the nitrogen source reagent or the sulfur source reagent is 1:(0.5 to 2).
[0029] S2. Preparation of cobalt-iron layered double metal hydroxide: Ultrasonically clean nickel foam with 0.5M to 2M hydrochloric acid, ethanol and water respectively, and put the cleaned nickel foam into a hydrothermal reaction kettle; dissolve an iron source, a cobalt source, a complexing agent and urea in deionized water, stir evenly and transfer to the reaction kettle equipped with nickel foam, and react at 110°C to 150°C for 6 to 15 hours; after the reaction is completed, take out the nickel foam grown with CoFe-LDH and wash it with deionized water and ethanol.
[0030] S3. Preparation of CoFe-LDH@N-GQDs / NF composite catalyst: Dissolve the graphene quantum dots prepared in S1 in deionized water to prepare a graphene quantum dot solution, add the graphene quantum dot solution and the nickel foam grown with CoFe-LDH into the reaction kettle, and react at 140°C to 160°C for 2 to 5 hours, and finally obtain the CoFe-LDH@N-GQDs / NF composite catalyst after washing and drying.
[0031] Among them, in step S1, the carbon source is citric acid, and the nitrogen source reagent or the sulfur source reagent is thiourea. The carbon source can also be small molecule organic acids such as ascorbic acid and tartaric acid, small molecule sugars such as glucose, fructose and sucrose, and aromatic compounds such as aniline, phenylenediamine, pyrocatechol, benzoic acid and salicylic acid; the nitrogen source reagent can also be any one of urea, ethylenediamine, lysine, glutamic acid, ammonia water and hydrazine; the sulfur source reagent can also be any one of sodium thiosulfate, cysteine or thioglycolic acid.
[0032] In step S2, the iron source is cobalt nitrate nonahydrate, the cobalt source is cobalt nitrate hexahydrate, and the complexing agent is citric acid. The iron source can also be any one of ferrous sulfate and ferric chloride hexahydrate; the cobalt source can also be any one of cobalt sulfate heptahydrate, cobalt chloride hexahydrate, cobalt sulfate heptahydrate, and cobalt chloride hexahydrate; the complexing agent can also be sodium citrate or ammonium fluoride.
[0033] In step S2, the molar ratio of the iron source, cobalt source, complexing agent, and urea is 1:1:(0.5 - 2):(1 - 5).
[0034] In step S3, the concentration of the graphene quantum dot solution is 0.1 - 10 mg / mL.
[0035] In step S3, the mass ratio of the graphene quantum dot solution to the nickel foam grown with CoFe-LDH is 1:(0.08 - 0.24).
[0036] The present invention also provides a two-dimensional material-supported graphene quantum dot catalyst prepared by the above preparation method, and the two-dimensional material-supported graphene quantum dot catalyst is used in the fields of electrocatalytic hydrogen evolution and electrocatalytic oxygen evolution.
[0037] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.
[0038] Example 1
[0039] This example provides a preparation method of a two-dimensional material-supported graphene quantum dot catalyst, including the following steps:
[0040] S1. Preparation of graphene quantum dots: Dissolve 19.5 mmol of citric acid and 24 mmol of thiourea in 60 mL of deionized water, stir evenly, transfer to a reaction kettle, and react at 175 °C for 20 hours. After the reaction is completed, take out the product and centrifuge, and take the supernatant for dialysis and freeze-drying to obtain graphene quantum dots.
[0041] S2. Preparation of cobalt-iron layered double metal hydroxide: Use 1M hydrochloric acid, ethanol, and water to ultrasonically clean the nickel foam for 10 minutes respectively, and put the cleaned nickel foam into a hydrothermal reaction kettle. Dissolve 2 mmol of iron nitrate nonahydrate, 2 mmol of cobalt nitrate hexahydrate, 0.5 mmol of citric acid, and 5 mmol of urea in 60 mL of deionized water, stir evenly, and transfer to a 2×2 cm 2In a reaction kettle with nickel foam, the reaction was carried out at 120 °C for 10 hours. After the reaction ended, the nickel foam grown with CoFe-LDH was taken out, washed with deionized water and ethanol, and then vacuum dried at 60 °C.
[0042] S3. Preparation of CoFe-LDH@N-GQDs / NF composite catalyst: Graphene quantum dots were dissolved in deionized water to prepare a 1 mg / mL graphene quantum dot solution. 20 mL of the graphene quantum dot solution and the nickel foam grown with CoFe-LDH were added to the reaction kettle, and the reaction was carried out at 150 °C for 3 hours. Finally, the CoFe-LDH@N-GQDs / NF composite catalyst was obtained after washing and drying.
[0043] Experimental tests
[0044] (I) The scanning electron microscopy (SEM) image of CoFe-LDH@N-GQDs / NF in Example 1 is as Figure 1 shown. It can be seen from the figure that the catalyst has a tremella-like layered structure. This structure increases the specific surface area and exposes more catalytic active sites, thus improving the catalytic activity.
[0045] (II) The X-ray diffraction (XRD) pattern of CoFe-LDH@N-GQDs / NF in Example 1 is as Figure 2 shown. It can be seen from the figure that the diffraction peaks at 44.5°, 52° and 76.5° correspond to the crystal planes of metal Ni in the nickel foam, and the remaining diffraction peaks belong to CoFe-LDH. Since the diffraction peak of N-GQDs overlaps with the peak position of CoFe-LDH, the characteristic peak of N-GQDs was not observed in the XRD spectrum.
[0046] (III) All electrochemical tests were completed on a CHI660E electrochemical workstation. 1 M KOH solution was used as the electrolyte, and a three-electrode system was adopted. Among them, a graphite rod was used as the counter electrode, and a Hg / HgO electrode was used as the reference electrode. All potentials were calibrated to the reversible hydrogen electrode potential (RHE) through the formula:
[0047]
[0048] After activation by cyclic voltammetry, the linear sweep voltammogram was measured at a scan rate of 5 mV s -1 . The chronoamperometry curve was tested under the condition of 170 mV (vs. RHE).
[0049] As [[ID=-31]] Figure 3 shown, CoFe-LDH@N-GQDs / NF at 10 mA / cm 2The overpotential is only 95 mV at a current density of , while the overpotential of CoFe-LDH without graphene quantum dots is 174 mV, and the overpotential of blank nickel foam (NF) is 248 mV. This indicates that CoFe-LDH itself has certain catalytic activity, and after adding graphene quantum dots, its catalytic activity is significantly improved. This is because graphene quantum dots provide additional catalytic active sites and regulate the electronic structure, enhancing the electron transfer conductivity.
[0050] As Figure 4 shown, CoFe-LDH@N-GQDs / NF was subjected to an i-t test at a potential of 170 mV (vs. RHE). After continuous testing for 100 hours, its overpotential did not change significantly, indicating that the catalyst has good stability.
[0051] Example 2
[0052] The difference between this example and Example 1 is only that the amount of citric acid in Example 1 was changed to 39 mmol, and the rest are the same as in Example 1, so they will not be repeated here.
[0053] Example 3
[0054] The difference between this example and Example 1 is only that 19.5 mmol of citric acid in Example 1 was changed to 19.5 mmol of ascorbic acid, and the rest are the same as in Example 1, so they will not be repeated here.
[0055] Example 4
[0056] The difference between this example and Example 1 is only that 24 mmol of thiourea in Example 1 was changed to 24 mmol of ethylenediamine, and the rest are the same as in Example 1, so they will not be repeated here.
[0057] Example 5
[0058] The difference between this example and Example 1 is only that 2 mmol of cobalt nitrate hexahydrate in Example 1 was changed to 2 mmol of nickel nitrate hexahydrate, and the rest are the same as in Example 1, so they will not be repeated here.
[0059] Example 6
[0060] The difference between this example and Example 1 is only that 0.5 mmol of citric acid in Example 1 was changed to 0.5 mmol of sodium citrate, and the rest are the same as in Example 1, so they will not be repeated here.
[0061] Example 7
[0062] The difference between this example and Example 1 is only that 0.5 mmol of citric acid in Example 1 was changed to 0.5 mmol of ammonium fluoride, and the rest are the same as in Example 1, so they will not be repeated here.
[0063] Example VIII
[0064] The difference between this example and Example I is only that the graphene quantum dot solution with a concentration of 1 mg / mL in Example I is changed to 2 mg / mL, and the rest are the same as those in Example I, so they will not be repeated here.
[0065] Example IX
[0066] The difference between this example and Example I is only that in step S2, the input amounts of ferric nitrate nonahydrate and cobalt nitrate hexahydrate are 2 mmol and 1.5 mmol respectively, and the rest are the same as those in Example I, so they will not be repeated here.
[0067] Example X
[0068] The difference between this example and Example I is only that in step S2, the input amounts of ferric nitrate nonahydrate and cobalt nitrate hexahydrate are 2.0 mmol and 1.0 mmol respectively, and the rest are the same as those in Example I, so they will not be repeated here.
[0069] Example XI
[0070] The difference between this example and Example I is only that in step S2, the input amounts of ferric nitrate nonahydrate and cobalt nitrate hexahydrate are 1.0 mmol and 2.0 mmol respectively, and the rest are the same as those in Example I, so they will not be repeated here.
[0071] The CoFe-LDH@N-GQDs / NF prepared in Example X and Example XI was subjected to i-t test at a potential of 170 mV (vs. RHE). After continuous testing for 100 hours, its overpotential did not change significantly, indicating that both catalysts also have good stability.
[0072] In summary, a two-dimensional material supported graphene quantum dot catalyst, its preparation method and application disclosed by the present invention load graphene quantum dots on CoFe-LDH grown on nickel foam through a secondary hydrothermal method. Since the graphene quantum dots increase the catalytic active sites and regulate the electronic structure, enhancing charge transfer and conductivity. The prepared CoFe-LDH@N-GQDs / NF has significantly improved catalytic performance compared with CoFe-LDH / NF and has good stability.
[0073] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and do not limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A preparation method of a two-dimensional material supported graphene quantum dot catalyst, characterized in that, The graphene quantum dots are loaded on CoFe-LDH grown on nickel foam by a secondary hydrothermal method, including the following steps: S1. Preparation of graphene quantum dots; S2. Preparation of cobalt-iron layered double hydroxide: Ultrasonically clean nickel foam with 0.5M - 2M hydrochloric acid, ethanol and water respectively, and put the cleaned nickel foam into a hydrothermal reaction kettle; Dissolve an iron source, a cobalt source, a complexing agent and urea in deionized water, stir evenly and transfer it to the reaction kettle containing nickel foam, and react at 110°C - 150°C for 6 - 15 hours; After the reaction is completed, take out the nickel foam grown with CoFe-LDH and wash it with deionized water and ethanol; S3. Preparation of CoFe-LDH@N-GQDs / NF composite catalyst: Dissolve the graphene quantum dots prepared in S1 in deionized water to prepare a graphene quantum dot solution, add the graphene quantum dot solution and the nickel foam grown with CoFe-LDH into the reaction kettle, and react at 140°C - 160°C for 2 - 5 hours, and finally obtain the CoFe-LDH@N-GQDs / NF composite catalyst after washing and drying.
2. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, characterized in that, In step S1, the carbon source is citric acid, the nitrogen source reagent or sulfur source reagent is thiourea, and the solvent is deionized water.
3. The preparation method of a two-dimensional material-supported graphene quantum dot catalyst according to claim 1, wherein, In step S1, the carbon source is any one of small molecule organic acids, small molecule sugars or aromatic compounds; the nitrogen source reagent is any one of urea, ethylenediamine, lysine, glutamic acid, ammonia water or hydrazine; the sulfur source reagent is any one of sodium thiosulfate, cysteine or thioglycolic acid.
4. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, wherein, In step S2, the iron source is cobalt nitrate nonahydrate, the cobalt source is cobalt nitrate hexahydrate, and the complexing agent is citric acid.
5. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, characterized in that, In step S2, the iron source is any one of ferrous sulfate and ferric chloride hexahydrate; the cobalt source is any one of cobalt sulfate heptahydrate, cobalt chloride hexahydrate, cobalt sulfate heptahydrate, cobalt chloride hexahydrate; the complexing agent is sodium citrate or ammonium fluoride.
6. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, characterized in that In step S2, the molar ratio of the cobalt source, iron source, complexing agent and urea is 1:(0.5 - 2):(0.5 - 2):(1 - 5).
7. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, characterized in that, In step S3, the concentration of the graphene quantum dot solution is 0.1 - 10mg / mL.
8. The preparation method of a two-dimensional material supported graphene quantum dot catalyst according to claim 1, wherein In step S3, the input mass ratio of the graphene quantum dot solution and the nickel foam grown with CoFe-LDH is 1:(0.08 - 0.24).
9. A two-dimensional material supported graphene quantum dot catalyst, characterized in that, The two-dimensional material loaded with graphene quantum dot catalyst is prepared by the preparation method described in any one of claims 1 - 8.
10. Use of the two-dimensional material supported graphene quantum dot catalyst as described in claim 9, characterized in that, The two-dimensional material loaded with graphene quantum dot catalyst is used in the fields of electrocatalytic hydrogen evolution and electrocatalytic oxygen evolution.