N, P co-doped porous carbon based on Enteromorpha, preparation method and application thereof

Abstract

The present invention discloses an N, P co-doped porous carbon based on Enteromorpha prolifera, and its preparation method and application. By means of microwave-assisted pre-oxidation treatment, the present invention uniformly mixes biomass and a chemical activator, introduces oxygen-containing functional groups on the surface and pore structure of the carbon material, increases the specific surface area of the porous carbon product, reduces the temperature of the carbonization process, and solves the problem that the pore structure of the carbon material is prone to collapse and damage at high temperatures; pickling is carried out by means of ultrasonic treatment, effectively solving the problem that impurities and activators are not thoroughly removed; the P element is incorporated by the phosphoric acid impregnation process, and Enteromorpha prolifera itself contains abundant N elements. The co-doping of N and P can effectively improve the conductivity of the porous carbon.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon material preparation, and in particular to an N, P co-doped porous carbon based on Enteromorpha prolifera, and a preparation method and application thereof. Background Art

[0002] The overgrowth of marine algae such as Enteromorpha prolifera has seriously affected the local marine ecological environment and ecological service functions, causing huge economic losses. In 2008 alone, the direct losses and cleaning costs caused by the green tide to Qingdao reached as high as 1.3 billion yuan. The green tide has gradually evolved into a regular marine disaster in the Yellow Sea area of China. At present, biomass raw materials are one of the important carbon sources for preparing porous carbon materials. Therefore, using algae biomass such as Enteromorpha prolifera as raw materials and preparing high-value porous carbon materials through technical means is a way to "turn waste into treasure". There are many traditional preparation methods for bio-based porous carbon, including high-temperature carbonization, activation, acid leaching and pickling processes, which have problems such as high cost, uneven pore size distribution, low biomass utilization rate, unfavorable for large-scale production, and poor properties of carbon material products. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related technologies to some extent.

[0004] To this end, an embodiment of the present invention provides an N, P co-doped porous carbon based on Enteromorpha prolifera, and a preparation method and application thereof.

[0005] In a first aspect, the present invention provides a preparation method of an N, P co-doped porous carbon based on Enteromorpha prolifera, including the following steps:

[0006] (a) Performing microwave-assisted pre-oxidation treatment on Enteromorpha prolifera powder and an activator in a high-temperature microwave device to obtain pre-oxidized powder;

[0007] (b) Adding a phosphoric acid solution to deionized water in which the pre-oxidized powder is dispersed for impregnation, and freeze-drying to obtain a biomass precursor;

[0008] (c) Carbonizing the biomass precursor in an inert gas to obtain a carbonized sample;

[0009] (d) Dispersing the carbonized sample into an acid pickling solution, and performing ultrasonic-assisted acid pickling to obtain an acid pickled sample.

[0010] Further, it further includes step (e) washing and vacuum drying the acid pickled sample to obtain a porous carbon sample.

[0011] Further, the Enteromorpha prolifera powder is obtained by grinding and sieving Enteromorpha prolifera after cleaning and drying.

[0012] Further, the activator is a bicarbonate, and the bicarbonate includes NaHCO 3, KHCO 3 One or both of them.

[0013] Furthermore, the high-temperature microwave equipment includes one of a microwave sintering furnace, a microwave tube furnace, a microwave ashing furnace, and a microwave reactor.

[0014] Furthermore, the power of the high-temperature microwave equipment is above 1000 W.

[0015] Furthermore, in step (c), the carbonization temperature of the carbonization treatment is 500-900 °C, and the carbonization time is 1-3 h.

[0016] Furthermore, the pickling solution in step (d) includes at least one of hydrochloric acid, nitric acid, and sulfuric acid.

[0017] Furthermore, the ultrasonic-assisted pickling time in step (d) is 5-20 min.

[0018] In a second aspect, the present invention provides a porous carbon prepared by the method proposed in the first aspect of the present invention.

[0019] In a third aspect, the present invention provides the application of the porous carbon prepared by the preparation method proposed in the first aspect of the present invention or the porous carbon proposed in the second aspect of the present invention in a catalyst support, a hydrogen storage material, and an electrode material.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention uses microwave-assisted pre-oxidation treatment to uniformly mix biomass and a chemical activator, introducing oxygen-containing functional groups on the surface and pore structure of the carbon material, increasing the specific surface area of the porous carbon product, reducing the carbonization process temperature, and solving the problem of easy collapse and damage of the pore structure of the carbon material at high temperatures; using ultrasonic treatment for pickling effectively solves the problem of incomplete removal of impurities and activators; the phosphorus impregnation process incorporates P elements, and the Enteromorpha itself is rich in N elements. The co-doping of N and P can effectively improve the conductivity of the porous carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0023] Figure 1 is a flowchart of the preparation method of the high-stability mesoporous carbon of the present invention;

[0024] Figure 2 is a block diagram of the preparation method of the high-stability mesoporous carbon of the present invention;

[0025] Figure 3 is a flowchart of the preparation method of the catalyst of the present invention;

[0026] Figure 4 Low - magnification scanning electron micrograph of the porous carbon prepared in Example 1 of the present invention

[0027] Figure 5 High - magnification scanning electron micrograph of the porous carbon prepared in Example 1 of the present invention

[0028] Figure 6 Low - magnification transmission electron micrograph of the porous carbon prepared in Example 1 of the present invention

[0029] Figure 7 High - magnification transmission electron micrograph of the porous carbon prepared in Example 1 of the present invention

[0030] Figure 8 EDS element mapping diagram of the porous carbon prepared in Example 1 of the present invention

[0031] Figure 9 Infrared spectrum diagram of the porous carbon prepared in Example 1 of the present invention

[0032] Figure 10 X - ray photoelectron spectroscopy diagram of the porous carbon prepared in Example 1 of the present invention

[0033] Figure 11 X - ray diffraction spectrum diagram of the porous carbon prepared in Example 1 of the present invention

[0034] Figure 12 Raman spectrum diagram of the porous carbon prepared in Example 1 of the present invention

[0035] Figure 13 N 2 adsorption - desorption isothermal curve of the porous carbon prepared in Example 1, Comparative Example 1 and 2 of the present invention

[0036] Figure 14 BET pore size distribution diagram of the porous carbon prepared in Example 1 of the present invention

[0037] Figure 15 Cyclic voltammogram of the catalyst prepared from the porous carbon of Example 1 and Comparative Example 2 of the present invention

[0038] Figure 16 Polarization curve of the catalyst prepared from the porous carbon of Example 1 and Comparative Example 1 of the present invention Detailed Description of the Invention

[0039] The embodiments of the present invention will be described in detail below. The examples are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] The preparation method of N, P co-doped porous carbon based on Enteromorpha prolifera according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0041] As Figure 1 and Figure 2 shown, the preparation method of N, P co-doped porous carbon based on Enteromorpha prolifera of the present invention includes the following steps:

[0042] (a) Performing microwave-assisted pre-oxidation treatment on Enteromorpha prolifera powder and an activator in a high-temperature microwave device to obtain pre-oxidized powder;

[0043] (b) Adding a phosphoric acid solution to deionized water in which the pre-oxidized powder is dispersed, impregnating, and freeze-drying to obtain a biomass precursor;

[0044] (c) Carbonizing the biomass precursor in an inert gas to obtain a carbonized sample;

[0045] (d) Dispersing the carbonized sample into an acid-washing solution and performing ultrasonic-assisted acid-washing to obtain an acid-washed sample;

[0046] (e) Washing and vacuum-drying the acid-washed sample to obtain a porous carbon sample.

[0047] In step (a), the Enteromorpha prolifera powder is obtained by grinding and sieving the washed and dried Enteromorpha prolifera. Specifically, fresh Enteromorpha prolifera is naturally obtained from the ocean, rinsed with distilled water to wash away excess seawater, and then dried; after drying, an appropriate amount of Enteromorpha prolifera is weighed and ground and crushed in an agate mortar, and the Enteromorpha prolifera powder is screened through a 150-mesh standard sieve.

[0048] The activator is a bicarbonate, and the bicarbonate includes one or both of NaHCO 3 , KHCO 3 . The mass ratio of Enteromorpha prolifera powder to bicarbonate is 1:1 to 1:5. In some embodiments, the mass ratio of Enteromorpha prolifera powder to bicarbonate is 1:1, 1:2, 1:3, 1:4, 1:5, or a value within the range composed of any two values.

[0049] When performing microwave-assisted pre-oxidation treatment, the Enteromorpha prolifera powder and the bicarbonate are placed in a crucible, and then the crucible is placed in a high-temperature microwave device. In an air atmosphere, at a power of more than 1000 W, microwave-assisted pre-oxidation treatment is performed for 0.5 to 1.5 h to ensure complete pre-oxidation. Through microwave-assisted technology for pre-oxidation treatment, oxygen-containing functional groups are introduced into the surface and pore structure of the carbon material, effectively reducing the carbonization temperature and increasing the specific surface area and stability.

[0050] In some embodiments, the power of the high-temperature microwave equipment is 1000W, 1500W, 1800W, 2000W or other suitable values. Among them, the high-temperature microwave equipment includes one of a microwave sintering furnace, a microwave tube furnace, a microwave ashing furnace, and a microwave reactor.

[0051] In step (b), the mass ratio of the Enteromorpha powder to the solute in the phosphoric acid solution is 1:1 to 1:4. In some embodiments, the mass ratio of the Enteromorpha powder to the solute in the phosphoric acid solution is 1:1, 1:2, 1:3, 1:4 or a value within the range composed of any two numerical values. The mass concentration of the phosphoric acid solution is 40% to 60%. In some embodiments, the mass concentration of the phosphoric acid solution is 40%, 50%, 60% or a value within the range composed of any two numerical values.

[0052] The purpose of impregnating with the phosphoric acid solution is to dope P element. The Enteromorpha itself contains rich N element. Co-doping of N and P can effectively improve the conductivity of the porous carbon. The specific process is as follows: First, disperse the pre-oxidized powder into deionized water, then add the phosphoric acid solution, soak in acid for more than 2h, and then dry in a freeze dryer for more than 48h.

[0053] In step (c), the carbonization temperature of the carbonization treatment is 500°C to 900°C, and the carbonization time is 1 to 3h to ensure complete carbonization of the biomass. The inert gas is nitrogen or argon, and the flow rate of the inert gas during carbonization is 15 to 30 mL / min. In some embodiments, the carbonization temperature is 500°C, 600°C, 700°C, 800°C, 900°C or a value within the range composed of any two numerical values. In some embodiments, the carbonization time is 1h, 2h, 3h or a value within the range composed of any two numerical values.

[0054] In step (d), it is an ultrasonic-assisted pickling process. The specific process is as follows: After carbonization is completed and cooled to room temperature, disperse the carbonized sample into the pickling solution, stir and mix evenly to form a slurry, and perform ultrasonic-assisted pickling treatment on the slurry for 5 to 20 min at a power of more than 300W in an air atmosphere. Pickling by ultrasound effectively solves problems such as incomplete removal of impurities and activators.

[0055] In some embodiments, the pickling solution includes at least one of hydrochloric acid, nitric acid, and sulfuric acid. It can be understood that the pickling solution can also be other suitable acidic solutions.

[0056] In some embodiments, the ultrasonic-assisted pickling time is 5 min, 10 min, 15 min, 20 min or a value within the range composed of any two numerical values.

[0057] In some embodiments, the ultrasonic-assisted pickling power is 300W, 500W, 700W, 900W or other suitable values.

[0058] The porous carbon of the present invention is prepared by the method for preparing N, P co-doped porous carbon based on Enteromorpha prolifera of the present invention.

[0059] The porous carbon of the present invention can be applied in catalyst carriers, hydrogen storage materials, and electrode materials.

[0060] In some embodiments, the porous carbon of the present invention is applied in a catalyst carrier. As Figure 3 shown, the method for preparing the catalyst includes the following steps:

[0061] Disperse the porous carbon into an ethanol solution, and add a precursor of a noble metal and mix evenly;

[0062] Add a reducing agent and a charged surfactant, and perform a reduction reaction with ultrasonic assistance, followed by centrifugal washing and vacuum drying to obtain a catalyst sample.

[0063] Among them, the porous carbon is the porous carbon proposed by the present invention or the porous carbon prepared by the method for preparing N, P co-doped porous carbon based on Enteromorpha prolifera of the present invention. The mass fraction of the ethanol solution is 1% - 30%. In some embodiments, the mass fraction of the ethanol solution is 1%, 5%, 10%, 15%, 20%, 25%, 30% or a value within the range composed of any two numerical values.

[0064] The noble metal precursor includes precursors of platinum, gold, iridium, and rubidium. For example, chloroplatinic acid, chloroauric acid, chloroiridic acid, or other suitable noble metal precursors. The mass fraction of the noble metal precursor is 20% - 80%. In some embodiments, the mass fraction of the noble metal precursor is 20%, 40%, 60%, 80% or a value within the range composed of any two numerical values.

[0065] The reducing agent includes one or more of HCHO, HCOONa, Na 2 SO 3 , NaBH 4 ; the charged surfactant includes one or more of quaternary ammonium salts, PPh 3 , PVP, and PVA. Among them, PPh 3 is triphenylphosphine, PVP is polyvinylpyrrolidone, and PVA is polyvinyl alcohol.

[0066] The ultrasonic power is 50W, 100W, 200W or other suitable values. After the reduction reaction is completed, the product is centrifugally washed multiple times and vacuum dried at 60°C - 80°C for 8 - 12h to ensure complete drying. Among them, the product is washed with deionized water and / or an ethanol solution.

[0067] Example 1

[0068] (1) Fresh Enteromorpha prolifera is washed with distilled water to remove excess seawater and then dried. Then, 100 g of dried Enteromorpha prolifera is weighed, ground in an agate mortar for 30 min, and the Enteromorpha prolifera powder is screened through a 150-mesh standard sieve. Weigh 1 g of the screened Enteromorpha prolifera powder, 1 g of NaHCO 3 、2 g of KHCO 3 and put them into a crucible, place it in a microwave reactor, and carry out microwave-assisted pre-oxidation at a power of 1500 W for 1 h to obtain pre-oxidized powder;

[0069] (2) Add the pre-oxidized powder to 20 mL of distilled water, then add phosphoric acid with a mass concentration of 50%. The mass ratio of the powder to the solute in the phosphoric acid solution is 1:1.2. Then dry it in a freeze dryer for 48 h to obtain a biomass precursor;

[0070] (3) Place the obtained biomass precursor in a high-temperature tubular furnace, in an N 2 atmosphere, carry out carbonization and activation treatment at 700 °C, with a heating rate of 3 °C / min and an N 2 flow rate of 20 mL / min. After carbonization for 2 h, cool it to room temperature to obtain a carbonized sample;

[0071] (4) Put the carbonized sample into a 50 mL beaker, then add 40 mL of 2 mol / L HCl solution, stir and mix evenly. Under a power of 300 W, carry out ultrasonic-assisted pickling treatment on the slurry for 15 min; Wash the pickled sample with ethanol aqueous solution multiple times until the pH becomes 6 to remove the residual activator and impurities, and then vacuum dry it at 60 °C for 12 h to obtain a porous carbon sample.

[0072] Comparative Example 1

[0073] (1) Fresh Enteromorpha prolifera is washed with distilled water to remove excess seawater and then dried. Then, 100 g of dried Enteromorpha prolifera is weighed, ground in an agate mortar for 30 min, and the Enteromorpha prolifera powder is screened through a 150-mesh standard sieve;

[0074] (2) Add the Enteromorpha prolifera powder to 20 mL of distilled water, then add phosphoric acid with a mass concentration of 50%. The mass ratio of the powder to the solute in the phosphoric acid solution is 1:1.2. Then dry it in a freeze dryer for 48 h to obtain a biomass precursor;

[0075] (3) Place the obtained biomass precursor in a high-temperature tubular furnace, in an N 2 atmosphere, carry out carbonization and activation treatment at 700 °C, with a heating rate of 3 °C / min and an N 2 flow rate of 20 mL / min. After carbonization for 2 h, cool it to room temperature to obtain a carbonized sample;

[0076] (4) Put the carbonized sample into a 50 mL beaker, then add 40 mL of 2 mol / L HCl solution, stir and mix evenly, and perform ultrasonic-assisted pickling treatment on the slurry for 15 min at a power of 300 W; wash the pickled sample with ethanol aqueous solution multiple times until the pH becomes 6 to remove the residual activator and impurities, and then vacuum dry at 60 °C for 12 h to obtain a porous carbon sample.

[0077] Comparative Example 2

[0078] (1) Wash the fresh enteromorpha with distilled water to remove the excess seawater and then dry it. Weigh 100 g of the dried enteromorpha, grind it in an agate mortar for 30 min, and sieve the enteromorpha powder through a 150-mesh standard sieve; weigh 1 g of the sieved enteromorpha powder, 1 g of NaHCO 3 , 2 g of KHCO 3 Put them into a crucible, place it in a microwave reactor, and perform microwave-assisted pre-oxidation at a power of 1500 W for 1 h to obtain a pre-oxidized powder;

[0079] (2) Add the pre-oxidized powder to 20 mL of distilled water, and then dry it in a freeze dryer for 48 h to obtain a biomass precursor;

[0080] (3) Place the obtained biomass precursor in a high-temperature tubular furnace, in an N 2 atmosphere, perform carbonization and activation treatment at 700 °C, with a heating rate of 3 °C / min and an N 2 flow rate of 20 mL / min. After carbonization for 2 h, cool it to room temperature to obtain a carbonized sample;

[0081] (4) Put the carbonized sample into a 50 mL beaker, then add 40 mL of 2 mol / L HCl solution, stir and mix evenly, and perform ultrasonic-assisted pickling treatment on the slurry for 15 min at a power of 300 W; wash the pickled sample with ethanol aqueous solution multiple times until the pH becomes 6 to remove the residual activator and impurities, and then vacuum dry at 60 °C for 12 h to obtain a porous carbon sample.

[0082] Test Example 1

[0083] Perform low-magnification scanning electron microscopy test, high-magnification scanning electron microscopy test, low-magnification transmission electron microscopy test and high-magnification transmission electron microscopy test on the porous carbon prepared in Example 1 respectively. The results are as Figures 4 to 7 shown. It can be seen from the figure that the porous carbon sample presents an ordered porous morphology structure, with a uniform pore size structure, belonging to the mesoporous size, which is beneficial to the subsequent preparation of hydrogen fuel cell catalysts and provides more reactive sites for redox reactions.

[0084] Test Example 2

[0085] Perform EDS analysis test on the porous carbon prepared in Example 1. The results are as Figure 8As shown in the figure, it can be seen that the porous carbon contains elements such as C, O, N, and P. The porous carbon prepared in the present invention has successfully incorporated N and P elements.

[0086] The porous carbon prepared in Example 1 was tested by infrared spectroscopy. The results are as Figure 9 shown. It can be seen from the figure that the porous carbon contains vibration peaks such as C═C, C═O, C-N, and C-P, indicating that the material contains elements such as N and P.

[0087] The porous carbon prepared in Example 1 was tested by X-ray photoelectron spectroscopy. The results are as Figure 10 shown. It can be seen from the figure that the porous carbon has obvious peaks related to C1s, O1s, N2p, and P2p, indicating that the structure of the porous carbon prepared in the present invention has incorporated N and P elements.

[0088] Test Example 3

[0089] The porous carbon prepared in Example 1 was tested by X-ray diffraction. The test results are as Figure 11 shown. It can be seen from the figure that the porous carbon has obvious diffraction peaks of (002) and (100), indicating that the porous carbon is an amorphous material, and the amorphous material has unique properties such as isotropy, defect distribution, and structural flexibility.

[0090] The porous carbon prepared in Example 1 was tested by Raman spectroscopy. The results are as Figure 12 shown. It can be seen from the figure that the porous carbon has obvious D and G peaks, and the I D / I G value is 1.21, indicating that the porous carbon material has a very high porosity and a rich defect density.

[0091] Test Example 4

[0092] The porous carbon prepared in Example 1, Comparative Example 1, and Comparative Example 2 was tested for nitrogen adsorption and desorption. The test results are as Figure 13 shown. It can be seen from the figure that the porous carbon prepared in Example 1 of the present invention has the highest specific surface area of 679.9 m 3 / g. The specific surface areas of the products obtained in Comparative Example 1 and Comparative Example 2 are 468.9 m 3 / g and 644.0 m 3 / g, respectively, indicating that the samples obtained by microwave-assisted pre-oxidation treatment have better pore structures and specific surface areas.

[0093] Test Example 5

[0094] The porous carbon samples prepared in Example 1, Comparative Example 1, and Comparative Example 2 were respectively tested for pore size distribution and thermal stability. The test results are shown in Table 1 and Figure 14 shown, where Figure 14Pore size distribution curve of the porous carbon prepared in Example 1.

[0095] <![CDATA[Specific surface area (m 3 / g)]]> Average pore diameter (nm) Thermal stability (°C) Example 1 679.9 22.7 ＞500 Comparative Example 1 468.9 31.0 ＞450 Comparative Example 2 644.0 23.1 ＞500

[0096] According to the above table, the porous carbon prepared in Example 1 has a higher specific surface area compared to Comparative Example 1 and Comparative Example 2, and the porous carbon prepared in Example 1 has high thermal stability.

[0097] Test Example 6

[0098] Using the porous carbon prepared in Example 1, Comparative Example 1, and Comparative Example 2 as carriers respectively to prepare catalysts, and using the prepared catalysts as anode catalysts to prepare membrane electrodes.

[0099] The specific preparation process of the catalyst is as follows: Weigh 500 mg of the porous carbon sample, disperse it in 100 ml of 50% ethanol - aqueous solution, add 335 mg of chloroplatinic acid, stir and dissolve for 20 min; then add 1 g of NaBH 4 reductant, add an appropriate amount of 0.5 g of charged surfactant PVA; under ultrasonic assistance with a power of 200 W, carry out a reduction reaction to prepare a porous carbon@Pt catalyst. After centrifugal washing with deionized water three times, vacuum dry at 60 °C for 12 h to obtain the catalyst sample.

[0100] The specific preparation process of the working electrode is as follows: Weigh 5 mg of the catalyst with an electronic balance, add 45 mg of 5% Nafion, 3 ml of ultrapure water, and 3 ml of isopropanol to the catalyst, and then ultrasonicate for 30 min with a power of 300 W to make the slurry fully mixed and uniform. During the ultrasonic process, keep the water bath temperature at about 20 °C; according to the range of catalyst loading on the electrode surface of 100 μg / cm 2 , take an appropriate amount of the dispersed slurry and evenly drop - coat it onto the surface of a smooth and clean disk electrode twice, and let it dry naturally completely to be used as the working electrode.

[0101] Using the membrane electrodes prepared with the catalysts using the porous carbon of Example 1 and Comparative Example 2 as carriers respectively as working electrodes, at 25 °C, in a three - electrode system, with N2 - saturated 0.1 mol / L HClO 4 as the electrolyte, in the scanning range of 0 - 1.2 V RHE , at a scanning rate of 50 mV / s, test the cyclic voltammetry performance. The test results are as Figure 15 shown. It can be seen from the figure that the noble metal catalysts prepared in Example 1 and Comparative Example 2 both have obvious redox catalytic properties, but the catalyst prepared in Example 1 has a larger electrochemical active area compared to the catalyst prepared in Comparative Example 2. The experimental results show that the porous carbon material doped with P element has better electrical conductivity and has a more excellent catalytic effect during the catalytic reaction process.

[0102] The membrane electrodes prepared with the catalysts using the porous carbons of Example 1 and Comparative Example 1 as carriers were used as the working electrodes, and 0.1 mol / L HClO 4 aqueous solution was passed through with high O 2 , purged for at least 30 min to achieve oxygen saturation; in a three-electrode system, at 25 °C, the rotational speed of the ring electrode was 1500 r / min, and in the potential scanning range of 0.2 - 1.2 V RHE , a forward scan was performed at a speed of 10 mV / s, and the polarization curve and the current density at 0.9 V RHE were recorded. The test results are as Figure 16 shown. It can be seen from the figure that the catalyst prepared with the porous carbon of Example 1 as the carrier achieved a current density of 5.23 mA / cm RHE at 0.9 V 2 , while Comparative Example 1 had only 2.69 mA / cm RHE current density at 0.9 V 2 . The experimental results show that through the pre-oxidation treatment by microwave-assisted means, oxygen-containing functional groups can be introduced into the porous carbon and the specific surface area can be increased, thereby making the corresponding porous carbon-based catalyst have stronger catalytic activity.

[0103] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0104] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0105] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purposes of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing N and P co-doped porous carbon based on Enteromorpha, characterized in that: The following steps are involved: (a) subjecting Enteromorpha powder and an activator to microwave-assisted preoxidation treatment in a high-temperature microwave device to obtain preoxidized powder; (b) adding a phosphoric acid solution into deionized water in which the pre-oxidized powder is dispersed, and then freeze-drying the mixture to obtain a biomass precursor; (c) carbonizing the biomass precursor in an inert gas to obtain a carbonized sample; (d) dispersing the carbonized sample into a pickling solution and performing ultrasonic-assisted pickling to obtain a pickled sample.

2. The preparation method according to claim 1, characterized in that The step also includes washing and vacuum drying the acid-washed sample to obtain a porous carbon sample.

3. The preparation method according to claim 1, characterized in that: The enteromorpha powder is obtained by grinding and sieving the washed, dried enteromorpha.

4. The preparation method according to claim 1, characterized in that: The activator is bicarbonate, and the bicarbonate includes one or two of NaHCO3 and KHCO3.

5. The preparation method according to claim 1, characterized in that: The high-temperature microwave equipment includes one of a microwave sintering furnace, a microwave tube furnace, a microwave ashing furnace, and a microwave reactor. The power of the high-temperature microwave equipment is above 1000W.

6. The preparation method according to claim 1, characterized in that: The carbonization temperature of the carbonization treatment in step (c) is 500-900° C., and the carbonization time is 1-3 hours.

7. The preparation method according to claim 1, characterized in that: The pickling solution in step (d) includes at least one of hydrochloric acid, nitric acid and sulfuric acid.

8. The preparation method according to claim 1, characterized in that: The ultrasonic-assisted pickling time in step (d) is 5 to 20 minutes.

9. A porous carbon, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the porous carbon prepared by the preparation method according to any one of claims 1 to 8 or the porous carbon according to claim 9 in catalyst carriers, hydrogen storage materials and electrode materials.

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