CN113998697A - Preparation method of leaf-based nitrogen-doped porous carbon and application of leaf-based nitrogen-doped porous carbon in oxygen reduction electrocatalysis in full pH range - Google Patents
Preparation method of leaf-based nitrogen-doped porous carbon and application of leaf-based nitrogen-doped porous carbon in oxygen reduction electrocatalysis in full pH range Download PDFInfo
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Abstract
The invention discloses a preparation method of leaf-based nitrogen-doped porous carbon and application of the leaf-based nitrogen-doped porous carbon in oxygen reduction electrocatalysis in a full pH range. Cleaning and drying the leaf-based biomass, and then grinding; weighing a certain amount of biomass powder material, soaking the biomass powder material in an acetic acid-sodium acetate solution containing hemicellulase, standing at a constant temperature for a period of time for hydrolysis, filtering, washing with water, drying, pre-carbonizing in an inert atmosphere, cooling to room temperature, grinding into powder, weighing with a nitrogen source and an activating agent according to a mass ratio, then carrying out high-energy vacuum mechanical force ball milling, carrying out high-temperature carbonization on a ball-milled mixture in an inert atmosphere, pickling, filtering, washing with water until filtrate is neutral, and drying to obtain the nitrogen-doped porous carbon material. According to the invention, the biomass is modified by using an enzyme-assisted high-energy vacuum mechanical force ball milling method, and the prepared nitrogen-doped porous carbon material has the advantages of large specific surface area, obvious hierarchical pore structure, rich nitrogen content and excellent ORR (organic rare earth) electrocatalytic activity in the full pH range (0-13).
Description
Technical Field
The invention belongs to the field of inorganic nano carbon materials and electrocatalysis, relates to nitrogen-doped porous carbon, and particularly relates to a preparation method of leaf-based nitrogen-doped porous carbon and application of the leaf-based nitrogen-doped porous carbon in oxygen reduction electrocatalysis in a full pH range.
Background
Energy is the material basis for human survival and development. The demand of human beings for energy is increasing in the present society. Therefore, the development of new efficient and renewable clean energy sources is becoming the focus of current research. The fuel cell is environment-friendly and efficient, is different from the traditional non-renewable energy, does not need to burn in the material/energy circulation process, does not generate toxic and harmful gas, can directly convert the chemical energy of the anode fuel into electric energy under the relatively mild condition, and has high energy conversion efficiency.
Oxygen Reduction Reaction (ORR) is not only a core reaction of fuel cells, but is also important in other energy conversion and energy storage technologies such as metal-air batteries. ORR is a complex, multiple electron gain-loss reaction. Therefore, the choice of electrocatalyst is especially important for the kinetic-retarded ORR. Precious metals such as platinum (Pt) and rhodium (Rh) have good electrocatalytic activity on ORR, but the precious metals are deficient in reserves, expensive and poor in stability, and are easily subjected to trace amounts of CO and H in the using process2S, etc. are poisoned and deactivated, which hinders the development and commercialization progress of fuel cell technology. Therefore, the research on the novel high-efficiency non-noble metal ORR electrocatalyst with excellent performance and good stability has profound significance.
The carbon material has excellent physical and chemical properties and can be used as an electrode material of an energy conversion and storage device. The biomass-based carbon material has wide sources, contains rich inorganic elements and special pore channel structures, so that the biomass can be used as a high-quality carbon precursor. Modification of carbon materials with heteroatoms, such as sulfur (S), boron (B), phosphorus (P), and nitrogen (N), can improve the wettability and conductivity of the surface of the carbon material, increase the number of reactive sites, and thereby improve the electronic and chemical properties of the carbon material and its intrinsic structure. Since N and C are in the same period in the periodic table and have close radii and both have many similar physical properties, nitrogen-doped carbon materials exhibit optimal ORR electrocatalytic activity.
At present, most of the successfully prepared biomass-based carbon materials have better ORR activity in alkaline electrolyte and are flat in neutral and acidic properties. For practical application to fuel cells (the electrolyte of a biofuel cell needs to be close to neutral; proton exchange membrane fuel cells typically use an acidic electrolyte), it is important to develop a high performance electrocatalyst suitable for use in the full pH range.
Disclosure of Invention
One of the purposes of the invention is to provide a preparation method of the leaf-based nitrogen-doped porous carbon, which has low cost, and the prepared porous carbon has excellent electrochemical performance and good stability.
The invention also aims to provide the application of the leaf-based nitrogen-doped porous carbon prepared by the preparation method in oxygen reduction electrocatalysis in the full pH range.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
in one aspect, the invention provides a preparation method of leaf-based nitrogen-doped porous carbon, which comprises the following steps:
the method comprises the following steps: cleaning, drying and grinding the leaf-based biomass to obtain a biomass powder material; weighing a certain amount of biomass powder material, soaking the biomass powder material in an acetic acid-sodium acetate buffer solution containing hemicellulase, standing at a constant temperature for a period of time for enzymolysis, and then filtering, washing and drying to obtain a material A;
step two: pre-carbonizing the material A in an inert gas atmosphere, cooling to room temperature, and grinding into powder to obtain a material B;
step three: respectively weighing the material B, a nitrogen source, activating agents potassium bicarbonate and potassium hydroxide according to the mass ratio, placing the materials in a vacuum ball milling tank, and carrying out vacuum high-energy mechanical ball milling after vacuumizing in the tank; carrying out high-temperature carbonization on the ball-milled mixture in an inert gas atmosphere to obtain a material C;
step four: and (3) pickling the material C, then washing with water until the filtrate is neutral, and drying to obtain the nitrogen-doped porous carbon material.
Preferably, the leaf-based biomass in step one is cypress leaves.
Preferably, the enzyme activity of the hemicellulase in the first step is 100-500U/g; the pH value of the buffer solution acetic acid-sodium acetate is 4.0-6.0; the enzymolysis temperature is 40-70 ℃, and the enzymolysis time is 12-48 h.
Preferably, the pre-carbonization temperature rise rate in the second step is 5 ℃/min, the temperature is raised to 400 ℃ and then maintained for 2h, and then the temperature is reduced to 300 ℃ at 5 ℃/min, and then the temperature is cooled to room temperature.
Preferably, the high-temperature carbonization process in the third step is as follows: heating to 300 deg.C at a rate of 5 deg.C/min for 2h, heating to 900 deg.C at a rate of 5 deg.C/min for 2h, cooling to 400 deg.C at 5 deg.C/min, and naturally cooling to room temperature.
Preferably, the nitrogen source in step three is one of melamine, dicyandiamide and urea.
Preferably, the material B is mixed with a nitrogen source, potassium bicarbonate (KHCO)3) And potassium hydroxide (KOH) in a mass ratio of 1:3:3: 1.
Preferably, the conditions of the vacuum high-energy mechanical force ball milling are as follows: the rotation speed is 300rpm, and the time is 30min, wherein the rotation speed is 15min clockwise and 15min anticlockwise.
Preferably, the acid washing in the fourth step is performed by using 1mol/L dilute hydrochloric acid solution at 60 ℃ and 300rpm for 3 h.
The invention also provides application of the nitrogen-doped porous carbon material prepared by the method in oxygen reduction electrocatalysis in the full pH range.
The nitrogen-doped porous carbon material can be used for oxygen reduction electrocatalytic reaction under alkaline, neutral and acidic conditions. The method comprises the following steps: weighing 3mg of the obtained nitrogen-doped porous carbon-based material in a centrifuge tube, adding 170 mu L of deionized water, 70 mu L of isopropanol and 10 mu L of 5% perfluorosulfonic acid-polytetrafluoroethylene (Nafion) solution, performing ultrasonic treatment for 60min to form uniform slurry, transferring 8 mu L of mixed slurry to be dispersed on the surface of a polished Rotating Disc Electrode (RDE), and airing at room temperature, namelyThe prepared working electrode. The prepared working electrode, a 3.5mol/L silver/silver chloride reference electrode and a platinum wire counter electrode form a three-electrode system under the conditions of alkalinity (0.1mol/L KOH, pH 13), neutrality (0.1mol/L PBS, pH 7) and acidity (0.5 mol/LH)2SO4pH 0) electrolyte, tested with an electrochemical workstation.
Compared with the prior art, the invention has the following beneficial effects:
(1) the carbon precursor used for preparing the nitrogen-doped porous carbon material is cypress branches and leaves which are widely distributed, low in cost and rich in hemicellulose;
(2) according to the invention, a novel, green and feasible enzyme is utilized to cooperate with a high-energy vacuum mechanical force ball milling method to modify a biomass, the method can regulate and control the pore structure of the surface of the cypress branches and leaves, and can effectively improve the doping efficiency of nitrogen atoms in a carbon frame, the finally prepared nitrogen-doped porous carbon material has large specific surface area, obvious hierarchical pore structure and rich nitrogen content, and the mass transfer of the nitrogen-doped porous carbon material in the oxygen reduction reaction process in the full pH range is promoted;
(3) the invention successfully synthesizes the biomass-based nitrogen-doped carbon material with excellent ORR electrocatalytic activity in the full pH range (0-13), thereby not only effectively promoting the commercialization process of the fuel cell, but also having simple and feasible experimental scheme and meeting the purposes of cleanness, environmental protection and resource recycling;
(4) the preparation method for regulating and controlling the pore structure of the biomass-based nitrogen-doped carbon material is simple, high in innovation degree and has great exploration and development space, the prepared nitrogen-doped porous carbon material is high in catalytic activity, and the oxygen reduction catalytic performance in alkaline, neutral and acidic electrolytes is obviously superior to that of other carbon-based materials of the same class. In 0.1mol/L KOH solution, the initial potential is close to 1.01V (relative to the reversible hydrogen electrode RHE), the half-wave potential is close to 0.85 (relative to the RHE), and the limiting current density is about-5.48 mA/cm2(ii) a In 0.1mol/L PBS solution, the initial potential is close to 0.91 (relative to RHE), the half-wave potential is close to 0.73 (relative to RHE), and the limiting current density is about-5.55 mA/cm2(ii) a At 0.5mol/L H2SO4In solution, the initial potential is connectedApproximately 0.88 (relative to RHE), a half-wave potential of approximately 0.73 (relative to RHE), and a limiting current density of approximately-5.62 mA/cm2. The ORR performance of the material under alkaline, neutral and acidic conditions is comparable to that of commercial 20% Pt/C. In addition, the material also has excellent methanol tolerance and long-term stability, and has wide application prospect.
Drawings
FIG. 1 is a Transmission Electron Micrograph (TEM) of a nitrogen-doped porous carbon material prepared in example 1;
fig. 2 is a high-resolution transmission electron microscope (HRTEM) image of the nitrogen-doped porous carbon material prepared in example 1;
FIG. 3 is a nitrogen isothermal (77K) adsorption and desorption curve of the nitrogen-doped porous carbon material prepared in example 1 and comparative examples 1 to 3;
FIG. 4 is a pore size distribution curve calculated based on a Density Functional Theory (DFT) model for nitrogen-doped porous carbon materials prepared in example 1 and comparative examples 1 to 3;
FIG. 5 is an N peak spectrum of X-ray photoelectron spectroscopy (XPS) of the nitrogen-doped porous carbon material prepared in example 1;
FIG. 6 is a Linear Sweep Voltammogram (LSV) at 1600rpm in 0.1mol/L KOH solution saturated with oxygen for the nitrogen-doped porous carbon materials prepared in example 1, comparative examples 1-3, and comparative example 4 at 20% Pt/C;
FIG. 7 is a Linear Sweep Voltammogram (LSV) at 1600rpm in 0.1mol/L PBS saturated with oxygen for the nitrogen-doped porous carbon materials prepared in example 1, comparative examples 1-3, and comparative example 4 at 20% Pt/C;
FIG. 8 is a graph of the oxygen saturation of 0.5mol/L H at 20% Pt/C for the nitrogen-doped porous carbon materials prepared in example 1, comparative examples 1-3, and comparative example 42SO4Linear Sweep Voltammogram (LSV) at 1600rpm in solution;
FIG. 9 is a methanol tolerance test of the nitrogen-doped porous carbon material prepared in example 1 and the 20% Pt/C of comparative example 4 in an oxygen-saturated 0.1mol/L KOH solution;
FIG. 10 is a methanol tolerance test of the nitrogen-doped porous carbon material prepared in example 1 and the 20% Pt/C of comparative example 4 in an oxygen-saturated 0.1mol/L PBS solution;
FIG. 11 is a graph of 20% Pt/C at 0.5mol/L H oxygen saturated for the nitrogen-doped porous carbon material prepared in example 1 and comparative example 42SO4Methanol tolerance test in solution;
FIG. 12 is a stability test of the nitrogen-doped porous carbon material prepared in example 1 and the 20% Pt/C of comparative example 4 in an oxygen-saturated 0.1mol/L KOH solution;
FIG. 13 is a stability test of the nitrogen-doped porous carbon material prepared in example 1 and the 20% Pt/C of comparative example 4 in an oxygen-saturated 0.1mol/L PBS solution;
FIG. 14 is a graph of 20% Pt/C at 0.5mol/L H oxygen saturated for the nitrogen-doped porous carbon material prepared in example 1 and comparative example 42SO4Stability test in solution.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples.
Example 1
Fully cleaning collected cypress leaves with deionized water, drying at 80 ℃, and slightly grinding with a mortar. Weighing 3.0g of the treated cypress leaves, soaking the cypress leaves in acetic acid-sodium acetate buffer solution (pH is 4.8) containing hemicellulase (enzyme activity is 200U/g), standing the cypress leaves in a constant-temperature water bath at 50 ℃ for 24 hours, filtering and washing the samples to be neutral after enzymolysis is finished, and drying the samples at 80 ℃. Putting the dried sample in N2Raising the temperature to 400 ℃ at the speed of 5 ℃/min under the atmosphere, carbonizing for 2h, then reducing the temperature to 300 ℃ at the speed of 5 ℃/min, and then cooling to room temperature to obtain the biochar. Grinding the pre-carbonized biochar with an agate mortar for 10min into powder, and bagging for later use.
Weighing 0.5g of biochar, 1.5g of melamine, 0.5g of potassium hydroxide and 1.5g of potassium bicarbonate, placing the biochar in a vacuum ball milling tank, exhausting air for 10min to enable the tank to be in a vacuum state, and then carrying out high-energy vacuum mechanical ball milling for 30min at 300rpm, wherein the clockwise time is 15min, and the anticlockwise time is 15 min. Placing the ball milled mixture in a tube furnace under N2Heating to 300 deg.C at a rate of 5 deg.C/min for 2h under protection, heating to 900 deg.C at a rate of 5 deg.C/min for 2h, cooling to 400 deg.C at 5 deg.C/min, and naturally cooling to room temperatureObtaining the nitrogen-doped porous carbon material which is not acid-washed. And (3) pickling the materials for 2h by using 1mol/L diluted hydrochloric acid solution at 60 ℃ and 300rpm, filtering, washing with water until filtrate is neutral, and drying to obtain the nitrogen-doped porous carbon material.
Weighing 3mg of the nitrogen-doped porous carbon material obtained in example 1 into a centrifuge tube, transferring 170 mu L of deionized water, 70 mu L of isopropanol solution and 10 mu L of 5% perfluorosulfonic acid-polytetrafluoroethylene copolymer (Nafion) solution by using a liquid transfer gun, performing ultrasonic treatment for 60min to form uniform dispersion liquid, sucking 8 mu L of mixed slurry drop on the surface of a polished Rotating Disk Electrode (RDE) by using the liquid transfer gun, and naturally drying at room temperature to obtain the prepared working electrode. The prepared working electrode, a 3.5mol/L silver/silver chloride reference electrode and a platinum wire counter electrode form a three-electrode system under the conditions of alkalinity (0.1mol/L KOH, pH 13), neutrality (0.1mol/L PBS, pH 7) and acidity (0.5 mol/LH)2SO4pH 0) electrolyte, tested with an electrochemical workstation. At O2Or N2And respectively scanning cyclic voltammetry curves and linear sweep voltammetry curves in the saturated electrolyte at the scanning speed of 5mV/s and 10 mV/s.
Comparative example 1
The difference from example 1 is: the treated cypress leaves were soaked in acetic acid-sodium acetate buffer solution (pH 4.8) containing cellulase (enzyme activity 200U/g).
The method for manufacturing the working electrode using the nitrogen-doped porous carbon material prepared in comparative example 1 as the oxygen reduction electrocatalyst and the electrochemical test method were the same as in example 1.
Comparative example 2
The difference from example 1 is: the treated cypress leaves were soaked in acetic acid-sodium acetate buffer solution (pH 4.8).
The method for manufacturing the working electrode using the nitrogen-doped porous carbon material prepared in comparative example 2 as the oxygen reduction electrocatalyst and the electrochemical test method were the same as in example 1.
Comparative example 3
The difference from example 1 is: 0.5g of biochar, 1.5g of melamine, 0.5g of potassium hydroxide and 1.5g of potassium bicarbonate are weighed into an agate mortar and manually ground for 30min (15 min clockwise and 15min counterclockwise).
The method for manufacturing the working electrode using the nitrogen-doped porous carbon material prepared in comparative example 3 as the oxygen reduction electrocatalyst and the electrochemical test method were the same as in example 1.
Comparative example 4
Weighing 1mg of 20% Pt/C in a centrifuge tube, transferring 170 mu L of deionized water, 70 mu L of isopropanol solution and 10 mu L of 5% perfluorosulfonic acid-polytetrafluoroethylene copolymer (Nafion) solution by using a liquid transfer gun, performing ultrasonic treatment for 60min to form uniform dispersion, sucking 8 mu L of mixed slurry by using the liquid transfer gun, dripping the mixed slurry on the surface of a polished Rotating Disk Electrode (RDE), and naturally airing at room temperature to obtain the prepared working electrode. The prepared working electrode, a 3.5mol/L silver/silver chloride reference electrode and a platinum wire counter electrode form a three-electrode system, and the three-electrode system is performed under the conditions of alkalinity (0.1mol/LKOH, pH 13), neutrality (0.1mol/L PBS, pH 7) and acidity (0.5mol/L H)2SO4pH 0) electrolyte, tested with an electrochemical workstation. At O2Or N2And respectively scanning cyclic voltammetry curves and linear sweep voltammetry curves in the saturated electrolyte at the scanning speed of 5mV/s and 10 mV/s.
(1) Transmission Electron Microscope (TEM) and High Resolution Transmission Electron Microscope (HRTEM) testing
The prepared nitrogen-doped porous carbon material (example 1) was observed under a transmission electron microscope (fig. 1) and a high-resolution transmission electron microscope (fig. 2). The biomass cell wall mainly comprises cellulose, hemicellulose and lignin which are tightly combined to form a natural three-dimensional reticular fiber structure. Among them, cellulose and lignin serve as a skeleton, hemicellulose serves as a filler, and hemicellulose is a heteropolymer composed of several different types of monosaccharides (such as pentasaccharides and hexasaccharides) and accounts for about 35% of biomass. The hemicellulose has loose structure, low polymerization degree and higher water solubility, and is easy to contact with hemicellulase to hydrolyze. The method treats the cypress leaves by utilizing the hemicellulase in cooperation with a high-energy vacuum mechanical force ball milling method, can regulate and control the surface aperture distribution of the cypress leaves, and can promote the effective doping rate of nitrogen atoms. As shown in fig. 1, the carbon material prepared by the hemicellulase in cooperation with the high-energy vacuum mechanical force ball milling method is in an irregular, light and thin gauze-like shape, and the surface of the carbon material contains abundant nano-pore structures (micropores/mesopores), which is helpful for increasing the specific surface area and the disorder degree of the carbon material. As shown in fig. 2, the nitrogen-doped carbon material not only has high surface roughness and a rich layered porous structure, but also contains obvious lattice stripes, which indicates that the carbon skeleton material has high graphitization degree. The abundant pore structure and high degree of graphitization are beneficial to the mass transport and electron conduction of nitrogen-doped carbon materials, which are important for the electrical catalytic activity of the ORR of the carbon material.
(2) Nitrogen isothermal adsorption and desorption test
Specific surface area and pore structure tests were performed on example 1, comparative example 2, and comparative example 3 using a nitrogen physisorption and desorption apparatus, respectively. As shown in FIG. 3, each of example 1, comparative example 2 and comparative example 3 has a micro-and mesoporous structure, and according to analysis, it corresponds to a specific surface area of 1616.77m, respectively2/g、1423.44m2/g、1301.29m2G and 1083.96m2(ii)/g; the total pore volume is 1.12cm3/g、1.11cm3/g、0.91cm3G and 0.88cm3(ii) in terms of/g. In combination with the pore size distribution curve calculated based on the DFT model (fig. 4), the enzyme-assisted vacuum mechanical force ball milling method does have an influence on the pore structure of the carbon-based material. The specific surface areas of the micropores calculated based on the DFT model in example 1, comparative example 2 and comparative example 3 were 1015.70m2/g、877.29m2/g、798.05m2G and 576.62m2The pore volume of each micropore is 0.40cm3/g、0.35cm3/g、0.31cm3G and 0.23cm3The corresponding mesoporous specific surface areas are 491.34m respectively2/g、439.78m2/g、410.05m2G and 418.80m2The mesoporous volume is 0.49cm3/g、0.46cm3/g、0.41cm3G and 0.47cm3(ii) in terms of/g. From this, it can be seen that the pore structures of example 1 (hemicellulase) and comparative example 1 (cellulase) are richer than those of comparative example 2, which does not use enzyme-assisted treatment, indicating that the use of enzyme-assisted treatment can indeed have an effect on the biomass pore distribution. The specific surface area of example 1 is larger than that of example 2, whichFurther indicates that the selection of proper enzyme species is more beneficial to the construction of a pore structure, thereby improving the ORR performance of the carbon material. In addition, the specific surface area and the pore volume of example 1 (high-energy vacuum mechanical ball milling) are larger than those of comparative example 3 (manual milling), because the high-energy vacuum mechanical ball milling method enables the activated pore-forming agent and the carbon-based material to be doped more uniformly, and the pore-forming effect is better during high-temperature carbonization at a later stage, which is beneficial to improving the specific surface area of the carbon-based material and increasing the mass transfer efficiency in the ORR.
(3) X-ray photoelectron spectroscopy (XPS) test
X-ray photoelectron spectroscopy (XPS) tests were performed on example 1, comparative example 2, and comparative example 3. The results show that the atomic percentages of the total nitrogen content of example 1, comparative example 2 and comparative example 3 are 4.13%, 3.54%, 2% and 2.52%, respectively, which indicates that nitrogen atoms have been successfully doped into the carbon framework and that the nitrogen content of example 1 (hemicellulase in conjunction with vacuum mechanical force ball milling) is the highest, suggesting that its ORR electrocatalytic activity is better than that of the other materials. The nitrogen content of example 1 is richer than that of comparative example 3, which shows that the high-energy vacuum mechanical force ball milling method for treating biomass enables the nitrogen source doping to be more uniform, and the nitrogen atom doping efficiency is improved. FIG. 5 is a narrow sweep peak curve of the nitrogen peak of example 1, which can be largely classified as pyridine nitrogen, pyrrole nitrogen, graphite nitrogen, and nitrogen oxide. Of which pyridine nitrogen and graphite nitrogen play a major role in ORR electrocatalytic activity. According to the analysis, the total relative contents of pyridine nitrogen and graphite nitrogen of example 1, comparative example 2 and comparative example 3 are 61.62%, 51.91%, 46.91% and 44.54%, respectively, and example 1 has the highest total nitrogen content and the highest ORR critical active site content.
(4) Oxygen reduction electrocatalytic performance test
Working electrodes were prepared from example 1, comparative example 2, comparative example 3 and comparative example 4, respectively, and combined with a silver/silver chloride reference electrode and a platinum wire counter electrode to form a three-electrode system in alkaline (0.1mol/L KOH), neutral (0.1mol/L PBS) and acidic (0.5mol/L H)2SO4) Linear Sweep Voltammetry (LSV) measurements were performed in the electrolyte at a sweep rate of 10 mV/s. FIG. 6, FIG. 7 and FIG. 8 show alkaline, neutral and acidic electrolysis, respectivelyLinear sweep voltammogram at 1600rpm in liquid.
Under alkaline conditions, the initial potentials of example 1, comparative example 2, comparative example 3 and comparative example 4 were 1.01V, 0.99V, 1.00V and 1.00V (relative to the reversible hydrogen electrode RHE), the half-wave potentials were 0.85V, 0.84V and 0.80V (relative to the RHE), the limiting current densities were-5.48 mA/cm2、-5.11mA/cm2、-4.50mA/cm2、-4.94mA/cm2And-5.30 mA/cm2(ii) a Under neutral conditions, the initial potentials of example 1, comparative example 2, comparative example 3 and comparative example 4 were 0.91V, 0.89V, 0.87V and 0.94V (relative to the reversible hydrogen electrode RHE), the half-wave potentials were 0.73V, 0.63V, 0.65V, 0.62V and 0.65V (relative to the RHE), the limiting current densities were-5.55 mA/cm, respectively2、-5.25mA/cm2、-5.02mA/cm2、-4.80mA/cm2And-5.38 mA/cm2(ii) a Under acidic conditions, the initial potentials of example 1, comparative example 2, comparative example 3 and comparative example 4 were 0.88V, 0.83V and 0.88V (relative to the reversible hydrogen electrode RHE), the half-wave potentials were 0.73V, 0.71V, 0.66V and 0.62V (relative to the RHE), the limiting current densities were-5.62 mA/cm, respectively2、-5.07mA/cm2、-4.60mA/cm2、-4.75mA/cm2And-5.30 mA/cm2(comparative example 4: 0.2V vs. RHE). The ORR electrocatalytic activity of example 1 is comparable to, or even superior to, comparative example 4, in alkaline, neutral and acidic electrolytes.
In addition, in order to meet the practical application requirements of the oxygen-reducing electrocatalyst, the methanol resistance test and the long-term stability test were performed for example 1 and comparative example 4. FIGS. 9 to 11 are methanol tolerance tests of the nitrogen-doped porous carbon material prepared in example 1 and the 20% Pt/C of comparative example 4 in oxygen-saturated alkaline, neutral and acidic electrolytes, respectively, and after methanol was injected into the electrolytes, the current of comparative example 4 sharply decayed under alkaline, neutral and acidic conditions, whereas example 1 was hardly affected by methanol and the current did not significantly change, indicating that example 1 has excellent resistance to methanolMethanol capacity. FIGS. 12 to 14 are the nitrogen-doped porous carbon material prepared in example 1 and 20% Pt/C of comparative example 4 at 0.1mol/L KOH, 0.1mol/L PBS and 0.5mol/L H saturated with oxygen, respectively2SO4Stability in solution test, after continuous operation for up to 12 hours, the current retention rates in the alkaline, neutral and acidic electrolytes were 92%, 95% and 96% respectively for example 1, while the current retention rates in the three electrolytes were 77%, 61% and 58% respectively for comparative example 4, and example 1 had better long-term stability. Therefore, the nitrogen-doped carbon material prepared by the method has outstanding oxygen reduction performance in all aspects, and is expected to become a substitute material of a commercial platinum-based ORR electrocatalyst.
As is apparent from comparison of example 1, comparative example 2 and comparative example 3 prepared according to the present invention, the enzyme-assisted high-energy vacuum mechanical force ball milling treatment method is closely related to the pore structure and nitrogen atom doping content of the carbon-based material. The method can effectively adjust the pore diameter structure of the cypress leaves, form rich nano-pore structures on the surface of the carbon precursor, increase the specific surface area of the carbon precursor, promote substance transfer and transportation in the ORR process, remarkably improve the doping efficiency of nitrogen atoms, and increase effective active sites on the surface of the carbon material, thereby promoting the ORR catalytic activity of the carbon-based material in the full pH range. The invention provides a novel and green preparation method capable of improving and improving the pore structure and the heteroatom doping efficiency of a carbon-based material, breaks through the original technical barrier, points out the direction of a new oxygen reduction electrocatalyst under the optimized full pH range, and has high innovation degree and wide application prospect.
Claims (10)
1. A preparation method of leaf-based nitrogen-doped porous carbon is characterized by comprising the following steps:
the method comprises the following steps: cleaning, drying and grinding the leaf-based biomass to obtain a biomass powder material; weighing a certain amount of biomass powder material, soaking the biomass powder material in an acetic acid-sodium acetate buffer solution containing hemicellulase, standing at a constant temperature for a period of time for enzymolysis, and then filtering, washing and drying to obtain a material A;
step two: pre-carbonizing the material A in an inert gas atmosphere, cooling to room temperature, and grinding into powder to obtain a material B;
step three: respectively weighing the material B, a nitrogen source, activating agents potassium bicarbonate and potassium hydroxide according to the mass ratio, placing the materials in a vacuum ball milling tank, and carrying out vacuum high-energy mechanical ball milling after vacuumizing in the tank; carrying out high-temperature carbonization on the ball-milled mixture in an inert gas atmosphere to obtain a material C;
step four: and (3) pickling the material C, then washing with water until the filtrate is neutral, and drying to obtain the nitrogen-doped porous carbon material.
2. The method for preparing the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the leaf-based biomass in the step one is cypress leaves.
3. The preparation method of the leaf-based nitrogen-doped porous carbon according to claim 1, wherein the enzyme activity of the hemicellulase in the first step is 100-500U/g; the pH value of the acetic acid-sodium acetate buffer solution is 4.0-6.0; the enzymolysis temperature is 40-70 ℃, and the enzymolysis time is 12-48 h.
4. The method for preparing the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the pre-carbonization temperature rise rate in the second step is 5 ℃/min, the temperature is raised to 400 ℃ and then maintained for 2h, and then the temperature is lowered to 300 ℃ at 5 ℃/min and then cooled to room temperature.
5. The preparation method of the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the high temperature carbonization process in the third step is as follows: heating to 300 deg.C at a rate of 5 deg.C/min for 2h, heating to 900 deg.C at a rate of 5 deg.C/min for 2h, cooling to 400 deg.C at 5 deg.C/min, and naturally cooling to room temperature.
6. The method for preparing the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the nitrogen source in the third step is one of melamine, dicyandiamide and urea.
7. The method for preparing the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the mass ratio of the material B to the nitrogen source, the potassium bicarbonate and the potassium hydroxide in the third step is 1:3:3: 1.
8. The method for preparing the leaf-based nitrogen-doped porous carbon according to claim 1, wherein the conditions of the vacuum high-energy mechanical ball milling in the third step are as follows: the rotation speed is 300rpm, and the time is 30min, wherein the rotation speed is 15min clockwise and 15min anticlockwise.
9. The method for preparing the leaf-based nitrogen-doped porous carbon as claimed in claim 1, wherein the acid washing in the fourth step is performed by using 1mol/L diluted hydrochloric acid solution at 60 ℃ and 300rpm for 3 h.
10. Use of the nitrogen-doped porous carbon material prepared according to the method of claim 1 in oxygen reduction electrocatalysis over the full pH range.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104760948A (en) * | 2015-04-22 | 2015-07-08 | 燕山大学 | Preparation method for high-performance porous carbon electrode material for super capacitor |
| CN109037704A (en) * | 2018-07-09 | 2018-12-18 | 华南理工大学 | A kind of N doping 3D porous carbon materials and the preparation method and application thereof |
| CN109569696A (en) * | 2019-01-30 | 2019-04-05 | 中国矿业大学 | A kind of preparation method and its hydrogen reduction catalytic applications of N doping biomass porous carbon |
| CN109694071A (en) * | 2019-01-24 | 2019-04-30 | 中国矿业大学 | A kind of method and application preparing nitrogen-doped porous carbon material using coconut husk as raw material |
| CN109761234A (en) * | 2019-03-27 | 2019-05-17 | 青岛科技大学 | A kind of preparation method of the porous wooden base Carbon Materials of richness nitrogen |
| CN110028053A (en) * | 2019-05-16 | 2019-07-19 | 济宁医学院 | A kind of preparation method and applications of high nitrogen doped amount nano cages material |
| WO2020103635A1 (en) * | 2018-11-19 | 2020-05-28 | 华南理工大学 | Lignin porous carbon nano sheet, preparation method therefor, and application thereof in super capacitor electrode material |
| WO2020122836A2 (en) * | 2018-12-12 | 2020-06-18 | Yüksel Yeni̇lenebi̇li̇r Enerji̇ Anoni̇m Şi̇rketi̇ | Method for nitrogen-doped graphene production |
| CN111977651A (en) * | 2020-07-23 | 2020-11-24 | 大唐可再生能源试验研究院有限公司 | Preparation method of potassium carbonate chemically activated low-order carbon source based porous carbon |
| CN113247893A (en) * | 2021-06-15 | 2021-08-13 | 天津科技大学 | Woody biomass-based porous carbon material prepared by high-temperature hydrothermal assisted hydrolysis of cellulase, and application and method thereof |
-
2021
- 2021-11-03 CN CN202111297135.5A patent/CN113998697B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104760948A (en) * | 2015-04-22 | 2015-07-08 | 燕山大学 | Preparation method for high-performance porous carbon electrode material for super capacitor |
| CN109037704A (en) * | 2018-07-09 | 2018-12-18 | 华南理工大学 | A kind of N doping 3D porous carbon materials and the preparation method and application thereof |
| WO2020010750A1 (en) * | 2018-07-09 | 2020-01-16 | 华南理工大学 | Nitrogen-doped 3d porous carbon material, preparation method therefor and use thereof |
| WO2020103635A1 (en) * | 2018-11-19 | 2020-05-28 | 华南理工大学 | Lignin porous carbon nano sheet, preparation method therefor, and application thereof in super capacitor electrode material |
| WO2020122836A2 (en) * | 2018-12-12 | 2020-06-18 | Yüksel Yeni̇lenebi̇li̇r Enerji̇ Anoni̇m Şi̇rketi̇ | Method for nitrogen-doped graphene production |
| CN109694071A (en) * | 2019-01-24 | 2019-04-30 | 中国矿业大学 | A kind of method and application preparing nitrogen-doped porous carbon material using coconut husk as raw material |
| CN109569696A (en) * | 2019-01-30 | 2019-04-05 | 中国矿业大学 | A kind of preparation method and its hydrogen reduction catalytic applications of N doping biomass porous carbon |
| CN109761234A (en) * | 2019-03-27 | 2019-05-17 | 青岛科技大学 | A kind of preparation method of the porous wooden base Carbon Materials of richness nitrogen |
| CN110028053A (en) * | 2019-05-16 | 2019-07-19 | 济宁医学院 | A kind of preparation method and applications of high nitrogen doped amount nano cages material |
| CN111977651A (en) * | 2020-07-23 | 2020-11-24 | 大唐可再生能源试验研究院有限公司 | Preparation method of potassium carbonate chemically activated low-order carbon source based porous carbon |
| CN113247893A (en) * | 2021-06-15 | 2021-08-13 | 天津科技大学 | Woody biomass-based porous carbon material prepared by high-temperature hydrothermal assisted hydrolysis of cellulase, and application and method thereof |
Non-Patent Citations (3)
| Title |
|---|
| CHEN, M ET AL.: "Micro-sized porous carbon spheres with ultra-high rate capability for lithium storage", 《NANOSCALE》 * |
| CHRISTINA SCHNEIDERMANN ET AL.: "Solvent-Free Mechanochemical Synthesis of Nitrogen-Doped Nanoporous Carbon for Electrochemical Energy Storage", 《CHEMSUSCHEM》 * |
| 白秋红等: "基于农林废弃生物质的功能性多孔碳材料构筑及应用研究", 《中国化学会第一届农业化学学术讨论会论文集》 * |
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