CN111874886A - Nitrogen-doped porous carbon material and preparation method and application thereof - Google Patents
Nitrogen-doped porous carbon material and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of porous carbon materials, and discloses a nitrogen-doped porous carbon material and a preparation method and application thereof. The method comprises the following steps: 1) mixing triblock copolymer F127, an organic nitrogen source, magnesium chloride and potassium ferrate in a mixed solvent containing water, adding agarose, uniformly mixing, cooling to form hydrogel, and freeze-drying to obtain xerogel; 2) carbonizing the xerogel to obtain a nitrogen-doped porous carbon material; the carbonization treatment is to carbonize the dried gel at 800-900 ℃; or the carbonization treatment is to carry out primary carbonization, acid treatment and secondary carbonization on the xerogel. The method is simple, and the obtained nitrogen-doped porous carbon material has the advantages of large specific surface area, more defect sites, high nitrogen doping amount and excellent oxygen reduction performance. The nitrogen-doped porous carbon material is applied to electrocatalytic oxygen reduction reaction and is used as an electrocatalyst of the oxygen reduction reaction.
Description
Technical Field
The invention belongs to the field of porous carbon materials, and particularly relates to a nitrogen-doped porous carbon material and a preparation method and application thereof.
Background
The development of modern life and society is not free from energy sources, and energy systems based on fossil fuels are facing a series of problems such as exhaustion of fossil fuels, high carbon dioxide emission and the like, so that new clean renewable energy sources and efficient energy storage and conversion devices are required to be found to reform the energy systems. Super capacitors and fuel cells are promising energy storage and conversion devices. At present, the disadvantages of high cost, short service life, low efficiency and the like greatly limit the wide-range popularization of the fuel cell. The oxygen reduction reaction is a common reaction at the cathode of a fuel cell and largely determines the performance and life of the fuel cell. Many electrocatalysts suitable for oxygen reduction reactions have been developed, and among them, metal-free nanocarbon materials have been the focus of research due to their advantages of excellent activity, high conductivity and fluidity, adjustable structure and surface chemical properties, simple preparation method and economic feasibility.
However, when the existing carbon material is used as an electrocatalyst for oxygen reduction reaction, the oxygen reduction catalytic performance of the carbon material still needs to be improved. Meanwhile, the carbon material rich in defects still has excellent oxygen reduction reaction activity even under the condition of not doping other elements, which shows that the proper increase of defect sites has a certain promotion effect on the oxygen reduction performance.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a nitrogen-doped porous carbon material and a preparation method thereof. The nitrogen-doped porous carbon material has better electrocatalytic oxygen reduction reaction performance.
The invention also aims to provide application of the nitrogen-doped porous carbon material. The nitrogen-doped porous carbon material is applied to electrocatalytic oxygen reduction reaction, and is used as an electrocatalyst of the oxygen reduction reaction, in particular to a catalyst in a cathode of a fuel cell.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a nitrogen-doped porous carbon material comprises the following steps:
1) mixing triblock copolymer F127, an organic nitrogen source, magnesium chloride and potassium ferrate in a mixed solvent containing water, adding agarose, uniformly mixing, cooling to form hydrogel, and freeze-drying to obtain xerogel;
2) and carbonizing the xerogel to obtain the nitrogen-doped porous carbon material.
The magnesium chloride is magnesium chloride containing crystal water or without crystal water; the magnesium chloride containing crystal water is MgCl2·6H2O。
The organic nitrogen source is melamine (C)3N3(NH2)3)。
The mixed solvent is a mixed solvent of water and ethanol, and the volume ratio of the water to the ethanol is (1-1.5): 1.
the mass ratio of the triblock copolymer F127 to the organic nitrogen source to the potassium ferrate is (1.4-1.6): (3-5): (1.95-3.9); the molar ratio of the potassium ferrate to the magnesium chloride is (1-2): 1, preferably (1.2 to 1.7): 1; the mass ratio of the triblock copolymer F127 to the agarose is (1.4-1.6): (1.2-1.4).
The carbonization treatment is to carbonize the xerogel; further, the carbonization treatment is to carry out primary carbonization, acid treatment and secondary carbonization on the dried gel.
The temperature of the primary carbonization is 800-900 ℃.
Furthermore, the primary carbonization is to sequentially carry out low-temperature treatment, medium-temperature treatment and high-temperature treatment on the xerogel; the temperature of the low-temperature treatment is 170-200 ℃, the temperature of the medium-temperature treatment is 340-360 ℃, and the temperature of the high-temperature treatment is 800-900 ℃.
The time of low-temperature treatment, the time of medium-temperature treatment and the time of high-temperature treatment are independently 1-4 h, and preferably 2-4 h.
The temperature of the secondary carbonization is 800-900 ℃; the temperature of the secondary carbonization is preferably the same as that of the high-temperature treatment of the primary carbonization.
The time of the secondary carbonization is 1-4 h, preferably 2-4 h.
The temperature rise rates of the primary carbonization and the secondary carbonization are respectively and independently 1-10 ℃/min.
The acid adopted for the acid treatment is dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid; the concentration of the acid is 0.4-0.6 mol/L; the acid treatment is acid dipping treatment, wherein the dipping temperature is 75-80 ℃, and the dipping time is 11-13 h.
The carbonization treatment is carried out under a protective atmosphere.
The mass-volume ratio of the triblock copolymer F127 to the mixed solvent is (1.4-1.6) g/100 mL;
the potassium ferrate (K)2FeO4) The mass to volume ratio of the mixed solvent is (1.95-3.9) g/100 mL; the mass ratio of the agarose to the mixed solvent is (1.2-1.4) g/100 mL.
In the step 1), mixing is carried out at 78-82 ℃; and uniformly mixing at 78-82 ℃.
And the uniformly mixing means adding agarose, and stirring for 2-3 h.
The specific step of the step 1) is to uniformly mix the F127 with the mixed solvent, add the organic nitrogen source, the magnesium chloride and the potassium ferrate (K)2FeO4) Stirring, then adding agarose, continuing stirring, cooling, freeze-drying, obtaining xerogel. The mixing is stirring for 10-15 min.
The continuous stirring time is 2-3 h; in the specific step, the stirring time is 30-40 min.
The mixing, stirring and continuing stirring are carried out under the heating condition of 78-82 ℃.
The cooling is natural cooling.
The temperature of the freeze drying is-50 to-60 ℃; the freeze drying time is 48-72 h.
The pore volume of the nitrogen-doped porous carbon material is 0.52-0.88 cm3The pore diameter is 3.49-10.9 nm, the specific surface area is 365-863 m2/g。
The nitrogen-doped porous carbon material is applied to electrocatalytic oxygen reduction reaction and is used as an oxygen reduction reaction electrocatalyst, in particular to a catalyst in a fuel cell cathode.
The preparation method of the invention uses agarose as a carbon source, melamine as a nitrogen source and potassium ferrate (K)2FeO4) With magnesium chloride hexahydrate (MgCl)2·6H2O) is used as a precursor, and the following reaction is carried out in an ethanol-water mixed solution to generate magnesium hydroxide colloid and potassium chloride:
the generated potassium chloride etches the carbon material to generate more defect sites when being calcined at high temperature, hexagonal flaky magnesium oxide formed by dehydrating magnesium hydroxide at the temperature higher than 350 ℃ can serve as a template agent, agarose serving as a carbon source is adhered to the template agent, and finally the porous carbon material rich in defects is formed, so that the specific surface area of the carbon material is increased, and the nitrogen doping amount and the oxygen reduction performance are improved.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) according to the method, the template and the etching agent are generated in situ, all precursors are effectively and uniformly mixed to form gel, dry gel is obtained in a freeze-drying mode, so that the mixing uniformity of the gel before and after water loss is kept, the precursors are decomposed and carbonized step by step through a multi-stage calcination method, the template and the etching agent are uniformly dispersed in the gel, so that the formed carbon material has a large specific surface area, more defect sites and higher nitrogen doping amount, while the acid impregnation removes metal oxides, enriches oxygen-containing functional groups on the surface of the carbon material, which are beneficial to improving the oxygen reduction performance, the secondary carbonization can increase the graphitization degree of the carbon material, improve the specific surface area and the conductivity, and finally the nitrogen-doped porous carbon material with the high specific surface area and rich defects is synthesized;
(2) the raw materials of the invention are low in price, convenient and easily available, and are nontoxic and harmless to human bodies, and intermediate products harmful to the environment can not be generated.
Drawings
FIG. 1 is an SEM photograph of a nitrogen-doped porous carbon material obtained in example 2; the left and right images are at different magnifications;
FIG. 2 is a graph of the nitrogen adsorption/desorption isotherm and pore size distribution curve of the product obtained in examples 1 to 5, wherein A corresponds to the nitrogen adsorption/desorption isotherm graph and B corresponds to the pore size distribution curve;
FIG. 3 is a linear scan plot of the products obtained in examples 1-5 and Pt/C.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto. The molecular formula of F127 described in the examples of the present invention is PEO-PPO-PEO, and the molecular weight is about 12600.
Example 1
Nitrogen-doped porous carbon material (denoted as F)1-M1-800, wherein, F1,M1The preparation method comprises the following steps of respectively preparing potassium ferrate and magnesium chloride hexahydrate, wherein the molar ratio of the potassium ferrate to the magnesium chloride hexahydrate is 1:1, and 800 ℃ is selected as a high-temperature calcination temperature:
weigh 1.5g F127 (EO)106PO70EO106) Adding into ethanol-water solution prepared from 50mL water and 50mL ethanol, magnetically stirring in water bath at 80 deg.C for 10 min, sequentially adding 4.0g melamine, 2.0g MgCl2·6H2O, 1.95g of potassium ferrate, continuously stirring for 40 minutes, adding 1.4g of agarose, continuously stirring for 2.5 hours, pouring into a culture dish, and naturally cooling to form hydrogel; then the hydrogel is placed in a freeze drying box, a culture dish is covered by a preservative film with small holes, the culture dish is frozen and dried for 60 hours at the temperature of 50 ℃ below zero, to obtain white xerogel, transferring the xerogel into a porcelain boat, putting the porcelain boat into a tube furnace, heating the xerogel to 180 ℃ from room temperature at the heating rate of 2 ℃/min, calcining the xerogel for 2 hours in the nitrogen atmosphere, heating to 350 deg.C at a rate of 2 deg.C/min, calcining for 2 hr, heating to 800 deg.C at a rate of 5 deg.C/min, calcining for 4 hr, cooling to room temperature to obtain a large amount of off-white solid, soaking the obtained solid in 0.5mol/L dilute sulfuric acid at 80 deg.C for 11 hr, filtering, washing, placing the obtained black solid in a ceramic boat again, and (3) placing the mixture in a tube furnace, heating the mixture to 800 ℃ from room temperature at the heating rate of 5 ℃/min in the nitrogen atmosphere, calcining the mixture for 4 hours, and naturally cooling the mixture to room temperature to obtain a black solid, namely the F.1.0-M1.0-800。
Synthesis of F in this example1.0-M1.0Pore volume of-800 is 0.65cm3A pore diameter of 9.49nm and a specific surface area of 671m2/g。
Example 2
Nitrogen-doped porous carbon material (denoted as F)1-M1-850, wherein F1,M 1850 are respectively potassium ferrate and magnesium chloride hexahydrate, the molar ratio of the potassium ferrate to the magnesium chloride hexahydrate is 1:1, and 850 ℃ is selected as the high-temperature calcination temperature, and the preparation method specifically comprises the following steps:
2.8g F127 was weighed into an ethanol-water solution prepared from 120mL of water and 80mL of ethanol, and after magnetically stirring in a water bath at 78 ℃ for 15 minutes, 8.4g of melamine and 4.0g of MgCl were added in this order2·6H2O, 3.90g of potassium ferrate, continuously stirring for 30 minutes, adding 2.4g of agarose, continuously stirring for 3 hours, pouring into a culture dish, and naturally cooling to form hydrogel; then the hydrogel is placed in a freeze drying box, a culture dish is covered by a preservative film with small holes, and the culture dish is frozen and dried for 72 hours at the temperature of-55 ℃, to obtain white xerogel, transferring the xerogel into a porcelain boat, putting the porcelain boat into a tube furnace, heating the xerogel from room temperature to 170 ℃ at the heating rate of 2 ℃/min, calcining the xerogel for 3 hours in the nitrogen atmosphere, heating to 350 deg.C at a rate of 2 deg.C/min, calcining for 2 hr, heating to 850 deg.C at a rate of 5 deg.C/min, calcining for 3 hr, naturally cooling to room temperature to obtain a large amount of off-white solid, soaking the obtained solid in 0.5mol/L dilute sulfuric acid at 80 deg.C for 13 hr, filtering, washing, placing the obtained black solid in a ceramic boat again, and (3) placing the mixture in a tubular furnace, heating the mixture to 850 ℃ from room temperature at the heating rate of 5 ℃/min in the nitrogen atmosphere, calcining the mixture for 3 hours, and naturally cooling the mixture to room temperature to obtain a black solid, namely the F.1.0-M1.0-850。
Synthesis of F in this example1.0-M1.0Pore volume of-850 of 0.88cm3A pore diameter of 10.9nm and a specific surface area of 553m2/g。
Example 3
Nitrogen-doped porous carbon material (denoted as F)1-M1-900, wherein, F1,M1The preparation method of the potassium ferrate and the magnesium chloride hexahydrate respectively comprises the following steps of adding the potassium ferrate and the magnesium chloride hexahydrate in an amount of about 0.01mol per 100mL of ethanol-water solution, and selecting 900 ℃ for high-temperature calcination temperatureThe method comprises the following steps:
2.1g F127(Pluronic F127) was weighed into an ethanol-water solution of 80mL water and 60mL ethanol, magnetically stirred at 82 ℃ in a water bath for 10 minutes, and then 6.3g melamine and 2.8g MgCl were added2·6H2O, 2.73g of potassium ferrate, continuously stirring for 30 minutes, adding 1.82g of agarose, continuously stirring for 2 hours, pouring into a culture dish, and naturally cooling to form hydrogel; then the hydrogel is placed in a freeze drying box, a culture dish is covered by a preservative film with small holes, and the culture dish is frozen and dried for 48 hours at the temperature of 50 ℃ below zero, to obtain white xerogel, transferring the xerogel into a porcelain boat, putting the porcelain boat into a tube furnace, heating the xerogel to 190 ℃ from room temperature at the heating rate of 2 ℃/min, calcining the xerogel for 2 hours in the nitrogen atmosphere, heating to 340 ℃ at the heating rate of 2 ℃/min for calcining for 4 hours, heating to 900 ℃ at the heating rate of 5 ℃/min for calcining for 2 hours, naturally cooling to room temperature to obtain a large amount of off-white solid, soaking the obtained solid at 75 ℃ for 12 hours by using 0.5mol/L dilute sulfuric acid, filtering and washing, putting the obtained black solid into a porcelain boat again, and (3) placing the mixture in a tube furnace, heating the mixture to 900 ℃ from room temperature at the heating rate of 5 ℃/min in the nitrogen atmosphere, calcining the mixture for 2 hours, and naturally cooling the mixture to room temperature to obtain a black solid, namely the F.1-M1-900。
Synthesis of F in this example1.0-M1.0Pore volume of-900 was 0.56cm3Per g, pore diameter of 8.74nm, specific surface area of 578m2/g。
Example 4
Nitrogen-doped porous carbon material (denoted as F)1.5-M1-850, wherein F1.5,M1Respectively potassium ferrate and magnesium chloride hexahydrate, wherein the molar ratio of the potassium ferrate to the magnesium chloride hexahydrate is 1.5:1 (namely the amount of substances of the potassium ferrate to the magnesium chloride hexahydrate added to each 100mL of ethanol-water solution is 0.015mol and 0.01mol respectively), and 850 ℃ is selected as a high-temperature calcination temperature, and the preparation method specifically comprises the following steps:
3.0g of 3.0g F127 was weighed out and added to an ethanol-water solution prepared from 100mL of water and 100mL of ethanol, and after magnetic stirring in a water bath at 78 ℃ for 10 minutes, 9.0g of melamine and 4.0g of MgCl were added in this order2·6H2O, 5.97g of potassium ferrate, continuously stirring for 30 minutes, adding 2.4g of agarose, continuously stirring for 2 hours, pouring into a culture dish, and naturally cooling to form hydrogel; then the hydrogel is placed in a freeze drying box, a culture dish is covered by a preservative film with small holes, and the culture dish is frozen and dried for 72 hours at the temperature of minus 60 ℃, to obtain white xerogel, transferring the xerogel into a porcelain boat, putting the porcelain boat into a tube furnace, heating the xerogel from room temperature to 170 ℃ at the heating rate of 2 ℃/min, calcining the xerogel for 4 hours in the nitrogen atmosphere, heating to 360 deg.C at a rate of 2 deg.C/min, calcining for 3 hr, heating to 850 deg.C at a rate of 5 deg.C/min, calcining for 3 hr, naturally cooling to room temperature to obtain a large amount of off-white solid, soaking the obtained solid in 0.5mol/L dilute sulfuric acid at 80 deg.C for 12 hr, filtering, washing, placing the obtained black solid in a ceramic boat again, and (3) placing the mixture in a tubular furnace, heating the mixture to 850 ℃ from room temperature at the heating rate of 5 ℃/min in the nitrogen atmosphere, calcining the mixture for 3 hours, and naturally cooling the mixture to room temperature to obtain a black solid, namely the F.1.5-M1.0-850。
Synthesis of F in this example1.5-M1.0Pore volume of-850 of 0.75cm3A pore diameter of 3.49nm and a specific surface area of 863 m/g2/g。
Example 5
Nitrogen-doped porous carbon material (denoted as F)2-M1-850,F2,M 1850 is a preparation method of 0.02mol and 0.01mol of potassium ferrate and magnesium chloride hexahydrate respectively added into each 100mL of ethanol-water solution, and the high-temperature calcination temperature is 850 ℃, and the preparation method specifically comprises the following steps:
3.2g F127 was weighed into an ethanol-water solution prepared from 100mL of water and 100mL of ethanol, and after magnetically stirring in a water bath at 78 ℃ for 15 minutes, 10.0g of melamine and 4.0g of MgCl were added in this order2·6H2O, 7.8g of potassium ferrate, continuously stirring for 35 minutes, adding 2.4g of agarose, continuously stirring for 2 hours, pouring into a culture dish, and naturally cooling to form hydrogel; then placing the hydrogel in a freeze drying box, covering a culture dish with a preservative film with small holes, freezing and drying at-60 ℃ for 72 hours to obtain white xerogel, and transferring the xerogel to a porcelain boatPlacing the mixture in a tubular furnace, heating the mixture from room temperature to 200 ℃ at a heating rate of 2 ℃/min, calcining the mixture for 2 hours in a nitrogen atmosphere, heating the mixture to 350 ℃ at a heating rate of 2 ℃/min, calcining the mixture for 2 hours at a heating rate of 5 ℃/min to 850 ℃ for 2 hours, naturally cooling the mixture to room temperature to obtain a large amount of off-white solid, soaking the obtained solid in 0.5mol/L dilute sulfuric acid at 80 ℃ for 12 hours, filtering and washing the obtained solid, placing the obtained black solid in a porcelain boat again, placing the porcelain boat in the tubular furnace, heating the porcelain boat from room temperature to 850 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere, calcining the porcelain boat for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain the black solid, namely the F2.0-M1.0-850。
Synthesis of F in this example2.0-M1.0Pore volume of-850 of 0.52cm3G, pore diameter of 7.8nm, specific surface area of 365m2/g。
FIG. 1 is an SEM photograph of a nitrogen-doped porous carbon material obtained in example 2; the left and right images are at different magnifications. SEM images were obtained by observation using a scanning electron microscope, model Germany Zeiss Uldra 55. As can be seen from FIG. 1, the material is porous carbon with flake shape, and the fact that the hexagonal flake magnesium oxide generated in situ is used as a template agent has a certain effect on the formation of the morphology of the material is proved.
N treatment of the products obtained in examples 1 to 52Physical adsorption-desorption characterization and pore size distribution characterization were performed by using a full-automatic specific surface area and pore size analyzer model TriStar II 3020, Micromeritics, usa, and the results are shown in fig. 2. FIG. 2 is a graph of the nitrogen adsorption/desorption isotherm and pore size distribution curve of the product obtained in examples 1 to 5, wherein A corresponds to the nitrogen adsorption/desorption isotherm and B corresponds to the pore size distribution curve.
As is evident from plot a in fig. 2, all samples exhibited typical type IV adsorption isotherms and H4 hysteresis loops, resulting from either slotted pores formed by sheet packing or containing narrow slotted pores like activated carbon. Examples 1, 2 and 3 mainly change the high-temperature calcination temperature (the high-temperature calcination temperature has great influence on the structure and the performance of the product), and all three materials have large specific surface areas and certain oxygen reduction reaction under alkaline conditionsActive, wherein when the high-temperature calcination temperature is 850 ℃, the material F1.0-M1.0850 (example 2) has better oxygen reduction reaction performance than the other two. Examples 2,4 and 5 mainly change the amount of potassium ferrate added (the amount of potassium ferrate has a great influence on the structure and performance of the product), and at the same high-temperature calcination temperature, properly increasing the amount of potassium ferrate is beneficial to increasing the specific surface area of the material, so that the oxygen reduction performance is better, but when the amount of potassium ferrate is increased, the specific surface area of the material is reduced, and the oxygen reduction reaction performance is adversely affected. According to the pore size distribution result (as shown in B in FIG. 2), the mesoporous pores of the sample are uniformly distributed within the range of 3-5nm, and F2.0-M1.0The presence of mesopores at 10-20nm in 850 (example 5) may be caused by the addition of too much potassium ferrate.
The products obtained in examples 1-5 were characterized by Linear Scanning (LSV) and analyzed using an electrochemical workstation model IGS-6030 from guangzhou early sensu technologies ltd, the results of which are shown in fig. 3 and table 1. The test was carried out in an alkaline solution of 0.1mol/LKOH, with a sweep rate of 10 mV/s. For uniform comparison, the LSV curve of the rotating disk electrode at the rotating speed of 1600rpm is compared, and the half-wave potential of the curve is taken as a comparison standard for measuring the electrochemical oxygen reduction performance.
FIG. 3 is a linear scan plot of the products obtained in examples 1-5 and Pt/C, corresponding to the oxygen reduction performance of each material, and comparing the performance of the commercial catalyst Pt/C. The potential value on the abscissa is based on the Reversible Hydrogen Electrode (RHE). In FIG. 3, comparative sample F1.0M1.0-800 (example 1) (0.762V vs. RHE) and F1.0M1.0-900 (example 3) (0.739vvs. rhe), material F1.0M1.0The half-wave potential correction of-850 (example 2) was 0.776V vs. RHE, indicating a lower overpotential. Sample F after increasing the Fe content1.5M1.0The half-wave potential of-850 (example 4) increased to 0.828V vs. RHE, which is comparable to Pt/C, and the half-wave potential was only 8mV lower than commercial Pt/C, indicating that it has excellent oxygen reduction catalytic performance. Sample F as the amount of potassium ferrate continues to increase2.0M1.0The drop in half-wave potential of-850 (example 5) to 0.702V vs. rhe may result from a reduction in its porosity, resulting in the agglomeration or non-exposure of a large number of active sites, thereby affecting catalytic activity.
TABLE 1 half-wave potential of the products of examples 1-5 in 0.1M KOH solution
The nitrogen-doped carbon nanomaterial has good oxygen reduction reaction performance under alkaline conditions, the doping of nitrogen atoms changes the electrons and the geometric structure of the carbon material, and the generated surface functional groups, dangling bonds, defect sites and the like are beneficial to improving the electro-catalytic oxygen reduction performance. The oxygen-containing functional groups on the surface of the carbon material also play a certain role in improving the oxygen reduction activity. The nitrogen-doped porous carbon material has more defect sites, higher nitrogen doping amount, more active sites and high graphitization degree, and the nitrogen-doped porous carbon material has good oxygen reduction performance.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A preparation method of a nitrogen-doped porous carbon material is characterized by comprising the following steps: the method comprises the following steps:
1) mixing triblock copolymer F127, an organic nitrogen source, magnesium chloride and potassium ferrate in a mixed solvent containing water, adding agarose, uniformly mixing, cooling to form hydrogel, and freeze-drying to obtain xerogel;
2) carbonizing the xerogel to obtain a nitrogen-doped porous carbon material;
the carbonization treatment is to carbonize the dried gel at 800-900 ℃; or the carbonization treatment is to carry out primary carbonization, acid treatment and secondary carbonization on the xerogel.
2. The method for producing a nitrogen-doped porous carbon material according to claim 1, wherein:
the organic nitrogen source is melamine;
the molar ratio of the potassium ferrate to the magnesium chloride is (1-2): 1;
the temperature of the primary carbonization is 800-900 ℃; the temperature of the secondary carbonization is 800-900 ℃.
3. The method for producing a nitrogen-doped porous carbon material according to claim 2, wherein: the molar ratio of the potassium ferrate to the magnesium chloride is (1.2-1.7): 1;
the primary carbonization is to sequentially carry out low-temperature treatment, medium-temperature treatment and high-temperature treatment on the xerogel; the temperature of the low-temperature treatment is 170-200 ℃, the temperature of the medium-temperature treatment is 340-360 ℃, and the temperature of the high-temperature treatment is 800-900 ℃.
4. The method for producing a nitrogen-doped porous carbon material according to claim 3, wherein: the time of low-temperature treatment, the time of medium-temperature treatment and the time of high-temperature treatment are independently 1-4 h.
5. The method for producing a nitrogen-doped porous carbon material according to claim 1, wherein: the mass ratio of the triblock copolymer F127 to the organic nitrogen source to the potassium ferrate is (1.4-1.6): (3-5): (1.95-3.9); the mass ratio of the triblock copolymer F127 to the agarose is (1.4-1.6): (1.2-1.4);
the magnesium chloride is magnesium chloride containing crystal water or without crystal water;
the mixed solvent is a mixed solvent of water and ethanol, and the volume ratio of the water to the ethanol is (1-1.5): 1.
6. the method for producing a nitrogen-doped porous carbon material according to claim 1, wherein:
the time of the secondary carbonization is 1-4 h;
the acid adopted for the acid treatment is dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid; the concentration of the acid is 0.4-0.6 mol/L; the acid treatment is acid dipping treatment, wherein the dipping temperature is 75-80 ℃, and the dipping time is 11-13 h;
the carbonization treatment is carried out under a protective atmosphere.
7. The method for producing a nitrogen-doped porous carbon material according to claim 1, wherein: the mass-volume ratio of the triblock copolymer F127 to the mixed solvent is (1.4-1.6) g/100 mL;
in the step 1), mixing is carried out at 78-82 ℃; the mixing is carried out at 78-82 ℃;
the uniformly mixing means adding agarose, and stirring for 2-3 h;
the mixing time is 30-40 min.
8. A nitrogen-doped porous carbon material obtained by the production method according to any one of claims 1 to 7.
9. Use of the nitrogen-doped porous carbon material according to claim 8 in an electrocatalytic oxygen reduction reaction, wherein: the nitrogen-doped porous carbon material is used as an oxygen reduction reaction electrocatalyst.
10. Use according to claim 9, characterized in that: the electrocatalyst is a catalyst in the cathode of the fuel cell.
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| CN114976070A (en) * | 2022-06-29 | 2022-08-30 | 华南理工大学 | Method for preparing non-noble metal-nitrogen co-doped porous carbon material and application thereof |
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| US20160365216A1 (en) * | 2015-06-11 | 2016-12-15 | Massachusetts Institute Of Technology | Pyrolyzed porous carbon materials and ion emitters |
| CN107555434A (en) * | 2017-09-05 | 2018-01-09 | 桂林电子科技大学 | A kind of nitrating porous carbon materials based on agar and its preparation method and application |
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| CN114976070A (en) * | 2022-06-29 | 2022-08-30 | 华南理工大学 | Method for preparing non-noble metal-nitrogen co-doped porous carbon material and application thereof |
| CN114976070B (en) * | 2022-06-29 | 2024-01-30 | 华南理工大学 | Method for preparing non-noble metal-nitrogen co-doped porous carbon material and application thereof |
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