Carbon metal composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and discloses a carbon metal composite material and a preparation method and application thereof.The preparation method comprises the following steps that 1, water-soluble sulfonated asphalt, nickel salt and a solvent are mixed, then the solvent is removed, and a precursor is obtained; wherein the residual carbon rate of the water-soluble sulfonated asphalt carbonized at 800 DEG C is not less than 50 wt%; (2) carrying out carbonization treatment on the precursor; and (3) carrying out acid pickling on a product obtained by carbonization treatment. The carbon metal composite material prepared by the preparation method is rich and easy to adjust in pore structure, has a relatively high graphitization degree, has relatively high catalytic activity when being applied to an electrocatalytic oxidation-reduction reaction, and has certain methanol resistance.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a carbon-metal composite material, its preparation method, and its application. Background Technology

[0002] Fuel cells, due to their high specific energy, long lifespan, high reliability, and strong adaptability, are a hot research topic in the field of green and renewable energy. The oxygen reduction reaction (ORR) is a crucial reaction occurring at the cathode of a fuel cell; however, its spontaneous process is extremely slow and requires an electrocatalyst. To date, ORR electrocatalysts are divided into noble metal catalysts and non-noble metal catalysts. However, platinum-based catalysts remain the best. While noble metal catalysts offer the best catalytic performance, precious metals such as platinum and iridium are expensive, have low surface reserves, and are difficult to mine. Furthermore, they suffer from time-drift sensitivity and carbon monoxide deactivation, which are major obstacles to the widespread application of fuel cells and metal-air batteries.

[0003] On the one hand, due to the high cost, low activity, and durability issues of platinum electrodes in ORR (Ortho-Resistant Rating), more research efforts have been focused on designing and synthesizing non-precious metal catalysts with better ORR catalytic activity; however, the performance of non-precious metal catalysts still needs improvement. On the other hand, for metal / C catalysts, existing technologies typically require two or three steps, or even multiple carbonization steps, to enhance the graphitization degree of the carbon material. For example, the method for preparing carbon-coated materials disclosed in CN202110239768.4 involves three steps: pre-carbonization, carbon dioxide activation, and calcination; the preparation method disclosed in CN202010219247.8 involves two calcinations, crushing, and demagnetization. The method for preparing carbon-silicon materials disclosed in CN201910982731.3 requires grinding to achieve nanoscale silicon-aluminum dimensions and the addition of buffers, etc. Therefore, the synthesis process of carbon composite materials in existing technologies is relatively complex and costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of complex preparation process, high cost and insufficient ORR activity of carbon metal composite materials in the prior art, and to provide a carbon metal composite material, its preparation method and application. The preparation method is characterized by simple steps and low raw material cost, and the carbon metal composite material obtained has excellent ORR activity.

[0005] To achieve the above objectives, the present invention provides a method for preparing a carbon metal composite material, comprising the following steps:

[0006] (1) Mix water-soluble sulfonated asphalt, nickel salt and solvent, then remove the solvent to obtain the precursor;

[0007] The residual carbon content of the water-soluble sulfonated asphalt after carbonization at 800℃ is not less than 50wt%.

[0008] (2) The precursor is subjected to carbonization treatment;

[0009] (3) The product obtained by carbonization is acid washed.

[0010] Preferably, the nickel salt is selected from nickel chloride and / or nickel acetate;

[0011] Preferably, the mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated bitumen (calculated as C) is (50-90):100, more preferably (70-80):100.

[0012] A second aspect of the present invention provides a carbon metal composite material prepared by the above-described preparation method.

[0013] A third aspect of the present invention provides the application of the above-mentioned carbon metal composite material in electrocatalytic oxygen reduction reaction.

[0014] The method for preparing carbon-metal composite materials provided by this invention uses water-soluble sulfonated pitch as the carbon source. On the one hand, water-soluble sulfonated pitch is relatively inexpensive, enabling high-value utilization of pitch and effectively reducing the cost of carbon-coated nickel materials. On the other hand, water-soluble sulfonated pitch and nickel salts have good water solubility, allowing them to contact at the nanoscale during mixing. Furthermore, due to the high carbon residue of water-soluble sulfonated pitch, its combination with metallic Ni can effectively enhance the graphitization degree of the prepared carbon material, thereby improving the material's ORR performance. The carbon-metal composite material prepared by the above method has a rich and easily tunable pore structure, a high degree of graphitization, and exhibits high catalytic activity in electrocatalytic redox reactions, as well as certain methanol resistance. Attached Figure Description

[0015] Figure 1 Here are SEM images of the composite material obtained in Example 1;

[0016] Figure 2 Here is a SEM image of the composite material obtained in Example 4;

[0017] Figure 3 These are TEM images of the composite material obtained in Example 6;

[0018] Figure 4 Here is a SEM image of the composite material obtained in Example 8;

[0019] Figure 5 Here is a SEM image of the composite material obtained in Example 9;

[0020] Figure 6The LSV curve of the ORR reaction of the composite material prepared in Example 1 is shown.

[0021] Figure 7 The LSV curve of the ORR reaction of the composite material prepared in Example 2 is shown.

[0022] Figure 8 The LSV curve of the ORR reaction of the composite material prepared in Example 4 is shown.

[0023] Figure 9 The image shows the LSV curve of the ORR reaction of the composite material prepared in Example 7. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] The first aspect of this invention provides a method for preparing a carbon-metal composite material, comprising the following steps:

[0026] (1) Mix water-soluble sulfonated asphalt, nickel salt and solvent, then remove the solvent to obtain the precursor;

[0027] The residual carbon content of the water-soluble sulfonated asphalt after carbonization at 800℃ is not less than 50wt%.

[0028] (2) The precursor is subjected to carbonization treatment;

[0029] (3) The product obtained by carbonization is acid washed.

[0030] The method for preparing carbon-metal composite materials provided by this invention uses water-soluble sulfonated pitch as a carbon source. On the one hand, water-soluble sulfonated pitch is relatively inexpensive, enabling high-value utilization of pitch and effectively reducing the cost of carbon-coated nickel materials. On the other hand, water-soluble sulfonated pitch and nickel salts have good water solubility and can contact each other at the nanoscale during the mixing process. Furthermore, since water-soluble sulfonated pitch has a high carbon residue rate, it can effectively improve the graphitization degree of the prepared carbon material when combined with metallic Ni, thereby improving the ORR performance of the material.

[0031] In this invention, the term "water-soluble sulfonated bitumen" has the conventional definition in the art, referring to a water-soluble substance extracted from sulfonated bitumen. This invention allows for a wide range of choices regarding the composition of the water-soluble sulfonated bitumen, as long as the aforementioned residual carbon content requirement is met. Preferably, the residual carbon content of the water-soluble sulfonated bitumen carbonized at 800°C is 50-70 wt%, more preferably 60-65 wt%, for example, any value or range between 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, and 65 wt%. Within the above preferred range, it is beneficial to further improve the degree of graphitization of the carbon layer in the carbon-metal composite material, thereby enhancing the ORR catalytic activity of the catalyst.

[0032] In this invention, the method for testing the residual carbon content is as follows: under a nitrogen atmosphere, water-soluble sulfonated asphalt is carbonized at 800°C for 4 hours. The mass before carbonization is recorded as M0, and the mass after carbonization is recorded as M1. The residual carbon content (wt%) = M1 / M0 × 100%.

[0033] This invention does not particularly limit the source of the water-soluble sulfonated asphalt; it can be extracted from sulfonated asphalt using conventional methods in the art. For example, the preparation method of the water-soluble sulfonated asphalt includes: dissolving sulfonated asphalt in water under heating conditions, followed by solid-liquid separation. The liquid obtained after solid-liquid separation is dried to obtain the water-soluble sulfonated asphalt.

[0034] The present invention does not have a particular limitation on the amount of water used, as long as it is sufficient to fully dissolve the sulfonated asphalt. Preferably, the amount of sulfonated asphalt used is 10-20g relative to 100mL of water, and more preferably 12-15g.

[0035] Preferably, the heating reaction temperature is 60-100℃, more preferably 65-80℃; the time is 1-4h, more preferably 2-3h. The composite material prepared from the water-soluble sulfonated asphalt using the above-mentioned preferred embodiments has superior electrochemical properties.

[0036] The present invention does not impose any particular limitation on the composition of the sulfonated asphalt, but rather on the composition of the obtained water-soluble sulfonated asphalt. Preferably, the sulfonated asphalt contains 65-75 wt% C, more preferably 70-73 wt%, 20-30 wt% O, more preferably 24-28 wt%, 0.6-2 wt% N, more preferably 1-1.5 wt%, and 0.2-1.5 wt% S, more preferably 0.5-1 wt%.

[0037] This invention allows for a wide range of nickel salts; conventional nickel-containing soluble salts in the art can be used. Preferably, the nickel salt is selected from nickel chloride and / or nickel acetate. In particular, the inventors have discovered that carbon-metal composite materials prepared using nickel chloride as a raw material have a richer pore structure, a larger specific surface area, which facilitates electron transfer within the channels and results in excellent electrochemical performance.

[0038] According to some preferred embodiments of the present invention, the mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated pitch (calculated as C) is (50-90):100, for example, typical but not limiting mass ratios such as 50:100, 55:100, 60:100, 65:100, 70:100, 75:100, 80:100, 85:100, and 90:100. Preferably, the mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated pitch (calculated as C) is (70-80):100. In the above preferred embodiments, it is beneficial to further improve the ORR catalytic activity of the prepared carbon metal composite material.

[0039] The present invention does not have any particular limitation on the mixing method in step (1), as long as the components are fully dissolved and mixed evenly. Preferably, in step (1), the mixing is carried out under stirring conditions, the mixing temperature is 60-90℃, preferably 75-85℃, and the time is 1-5h, preferably 2-3h.

[0040] According to the present invention, preferably, the solvent is water. The entire preparation process eliminates the need for organic solvents, further reducing process costs and making it environmentally friendly.

[0041] According to some preferred embodiments of the present invention, the carbonization process is carried out under an inert atmosphere, which may be provided by nitrogen and / or argon.

[0042] Preferably, the carbonization temperature is 500-1000℃, more preferably 600-900℃, for example, it can be a specific carbonization temperature such as 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, or any range between two. Adopting the above preferred embodiment is beneficial for further improving the ORR catalytic activity of the prepared carbon-metal composite material. Preferably, the carbonization time is 1-4 hours, more preferably 2-3 hours, and the heating rate is 5-10℃ / min, more preferably 8-10℃ / min.

[0043] According to the present invention, the acid washing in step (3) removes at least part of the nickel on the surface of the carbon metal composite material, which is beneficial to control the number of pores on the surface of the composite material and obtain a suitable specific surface area, thereby further improving the ORR catalytic activity of the prepared carbon metal composite material.

[0044] Preferably, the acid washing includes contacting the product obtained from the carbonization treatment with an aqueous solution of acid, followed by washing and drying. The present invention does not particularly limit the type of acid; conventional organic and / or inorganic acids in the art can be used. Preferably, the acid is hydrochloric acid. Preferably, the concentration of the aqueous solution of acid is 1-6 mol / L, more preferably 1-2 mol / L.

[0045] Preferably, the contact temperature is 20-80℃, more preferably 70-80℃, and the contact time is 1-12h, more preferably 4-8h.

[0046] The present invention does not particularly limit the washing and drying methods and conditions, and can be carried out using conventional methods in the art. Preferably, the washing can be performed using water. The drying temperature is 20-100℃, preferably 60-80℃, and the time is 1-14 hours, preferably 5-12 hours.

[0047] A second aspect of the present invention provides a carbon metal composite material prepared by the above-described preparation method.

[0048] According to the present invention, preferably, the carbon metal composite material comprises nickel oxide and graphitized carbon coated on the surface of nickel oxide.

[0049] Preferably, in the carbon metal composite material, the mass ratio of Ni to C is (50-90):100, more preferably (60-80):100.

[0050] In this invention, the composition of the carbon metal composite material is obtained by X-ray photoelectron spectroscopy.

[0051] According to the present invention, preferably, the specific surface area of ​​the carbon metal composite material is 90-1000 m². 2 / g, preferably 300-900m 2 / g. In this invention, the specific surface area is obtained by testing using the BET method.

[0052] Preferably, the carbon-metal composite material has a spherical or plate-like structure. Preferably, the particle size of the spherical structure is 50-100 nm.

[0053] In this invention, the morphology of the carbon metal composite material is observed using a scanning electron microscope, and the particle size is measured using a scanning electron microscope.

[0054] According to some preferred embodiments of the present invention, the carbon metal composite material comprises nickel oxide and graphitized carbon coated on the surface of the nickel oxide, and the specific surface area of ​​the carbon metal composite material is 90-400 m². 2 / g, preferably 250-350m 2 / g, the carbon metal composite material is prepared by the following method:

[0055] A1. Mix water-soluble sulfonated asphalt, nickel acetate and solvent, then remove the solvent to obtain the precursor;

[0056] The residual carbon content of the water-soluble sulfonated asphalt after carbonization at 800℃ is not less than 50wt%.

[0057] A2. The precursor is subjected to carbonization treatment; the carbonization treatment conditions include: temperature of 850-950℃, time of 2-3h, and heating rate of 8-10℃ / min.

[0058] A2. The product obtained from carbonization is acid washed.

[0059] According to some preferred embodiments of the present invention, the carbon metal composite material comprises nickel oxide and graphitized carbon coated on the surface of the nickel oxide, and the specific surface area of ​​the carbon metal composite material is 400-1000 m². 2 / g, preferably 600-850m 2 / g, the carbon metal composite material is prepared by the following method:

[0060] B1. Mix water-soluble sulfonated asphalt, nickel chloride and solvent, then remove the solvent to obtain the precursor;

[0061] The residual carbon content of the water-soluble sulfonated asphalt after carbonization at 800℃ is not less than 50wt%.

[0062] B2. The precursor is subjected to carbonization treatment; the carbonization treatment conditions include: temperature of 700-800℃, time of 2-3h, and heating rate of 8-10℃ / min.

[0063] B2. The product obtained from the carbonization process is acid washed.

[0064] A third aspect of the present invention provides the application of the above-mentioned carbon metal composite material in electrocatalytic oxygen reduction reaction.

[0065] The present invention will be described in detail below through embodiments.

[0066] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available.

[0067] The sulfonated asphalt used in the examples came from Pingxiang, Jiangxi Province, and contained 71.08 wt% C, 26.80 wt% O, 1.31 wt% N, and 0.81 wt% S.

[0068] Example 1

[0069] Sulfonated bitumen was dissolved in distilled water at a concentration of 12 g / 100 mL. The solution was heated at 80°C for three hours. After heating, the liquid was collected by centrifugation. The collected liquid was then rotary evaporated to remove the water, yielding water-soluble sulfonated bitumen. The residual carbon content of this water-soluble sulfonated bitumen after carbonization at 800°C was 62 wt%.

[0070] Water-soluble sulfonated asphalt and nickel chloride were dissolved in deionized water. The mass ratio of nickel chloride (calculated as Ni) to water-soluble sulfonated asphalt (calculated as C) was 70:100. The mixture was stirred and heated at 80°C for three hours. After heating, the deionized water was removed by rotary evaporation. The mixture was then dried in an oven at 80°C for 12 hours to obtain the SP-NiCl2 composite material.

[0071] A certain amount of SP-NiCl2 composite material was placed in a tube furnace and heated to 800℃ at a rate of 10℃ / min under a N2 atmosphere, and then held at 800℃ for 2 hours. Afterwards, it was allowed to cool naturally in a nitrogen atmosphere. Once cooled, the carbon material was washed with 1 mol / L hydrochloric acid at 80℃ for 12 hours, then washed with deionized water until neutral. Finally, the carbon material was dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S1.

[0072] Observation using a scanning electron microscope, such as Figure 1 As shown, the composite material has a sheet-like morphology and a dense, porous, and fluffy surface structure. The specific surface area of ​​the composite material, as determined by BET analysis, is 793.03 m². 2 / g.

[0073] Example 2

[0074] Sulfonated asphalt was dissolved in distilled water at a concentration of 15 g / 100 mL. The solution was heated at 70°C for three hours. After heating, the liquid was collected by centrifugation. The collected liquid was then rotary evaporated to remove the water, yielding water-soluble sulfonated asphalt. The residual carbon content of this water-soluble sulfonated asphalt after carbonization at 800°C was 65 wt%.

[0075] Water-soluble sulfonated asphalt and nickel chloride were dissolved in deionized water. The mass ratio of nickel chloride (calculated as Ni) to water-soluble sulfonated asphalt (calculated as C) was 60:100. The mixture was stirred and heated at 80°C for three hours. After heating, the deionized water was removed by rotary evaporation. The mixture was then dried in an oven at 80°C for 12 hours to obtain the SP-NiCl2 composite material.

[0076] A certain amount of SP-NiCl2 composite material was placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min under a N2 atmosphere, and then held at 800℃ for 2 hours. Subsequently, it was allowed to cool naturally in a nitrogen atmosphere. After cooling, the obtained carbon material was washed with 1 mol / L hydrochloric acid at 80℃ for 6 hours, washed with deionized water until neutral, and then dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S2. Its morphology is similar to... Figure 1 Similarly, the specific surface area of ​​the composite material was 660.53 m² / g by BET testing. 2 / g.

[0077] Example 3

[0078] Water-soluble sulfonated bitumen was prepared according to the method in Example 1.

[0079] Water-soluble sulfonated asphalt and nickel chloride are dissolved in deionized water. The mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated asphalt (calculated as C) is 70:100. The mixture is stirred and heated at 80°C for three hours. After heating, the deionized water is removed by rotary evaporation. The mixture is then dried in an oven at 80°C for 12 hours to obtain the SP-NiCl2 composite material.

[0080] A certain amount of SP-NiCl2 composite material was placed in a tube furnace and heated to 600℃ at a heating rate of 10℃ / min under a N2 atmosphere, and then held at 600℃ for 2 hours. Subsequently, it was allowed to cool naturally in a nitrogen atmosphere. After cooling, the obtained carbon material was washed with 1 mol / L hydrochloric acid at 80℃ for 6 hours, washed with deionized water until neutral, and then dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S3. The morphology was observed using a scanning electron microscope and was similar to... Figure 1 Similarly, the specific surface area of ​​the composite material was determined to be 832.3 m² by BET testing. 2 / g.

[0081] Example 4

[0082] Water-soluble sulfonated asphalt and nickel acetate are dissolved in deionized water. The mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated asphalt (calculated as C) is 80:100. The mixture is stirred and heated at 80°C for 3 hours. After heating, the deionized water is removed by rotary evaporation. The mixture is then dried in an oven at 80°C for 12 hours to obtain the SP-Ni composite material.

[0083] A certain amount of SP-Ni composite material was placed in a tube furnace and heated to 900℃ at a rate of 10℃ / min under a N2 atmosphere, and then held at 900℃ for 2 hours. Afterwards, it was allowed to cool naturally in a nitrogen atmosphere. Once cooling was complete, the product was washed with 1 mol / L hydrochloric acid at 80℃ for 12 hours, and then washed with deionized water until neutral. Finally, the carbon material was dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S4.

[0084] Observation using a scanning electron microscope, such as Figure 2 As shown, numerous spherical structures are observed. Magnified to 500 nm, these structures exhibit a highly uniform and orderly arrangement, with dimensions ranging from 50 to 100 nm. Furthermore, relatively uniformly sized pores are observed on the surface of these spherical structures. BET testing revealed a specific surface area of ​​340.36 m² for the composite material. 2 / g.

[0085] Example 5

[0086] The method of Example 1 was followed, except that the carbonization temperature was 800°C and the carbonization time was 1 hour, resulting in carbon-coated nickel oxide material, denoted as S5.

[0087] The scanning electron microscope of this composite material and Figure 1 Similar, but the sample surface is rougher.

[0088] The specific surface area of ​​the composite material was determined to be 826.71 m² by BET testing. 2 / g.

[0089] Example 6

[0090] Water-soluble sulfonated bitumen was prepared according to the method in Example 1.

[0091] Water-soluble sulfonated bitumen and nickel acetate are dissolved in deionized water. The mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated bitumen (calculated as C) is 70:100. The mixture is stirred and heated at 80°C for 3 hours. After heating, the deionized water is removed by rotary evaporation. The mixture is then dried in an oven at 80°C for 12 hours to obtain the SP-Ni composite material.

[0092] A certain amount of SP-Ni composite material was placed in a tube furnace and heated to 700℃ at a rate of 10℃ / min under a N2 atmosphere, and then held at 700℃ for 2 hours. Afterwards, it was allowed to cool naturally in a nitrogen atmosphere. Once cooling was complete, the product was washed with 1 mol / L hydrochloric acid at 80℃ for 6 hours, and then washed with deionized water until neutral. Finally, the carbon material was dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S6.

[0093] Morphology and Figure 2 Similar to a spherical structure, it can be observed using a transmission electron microscope, such as... Figure 3 As shown, the sample exhibits a core-shell structure consisting of nickel oxide and a graphitized carbon shell coating the nickel oxide surface. The specific surface area of ​​the composite material, as determined by BET analysis, is 315.3 m². 2 / g.

[0094] Example 7

[0095] Following the method of Example 4, except that the mass ratio of nickel acetate (calculated as Ni) to the water-soluble sulfonated asphalt (calculated as C) was 70:100, a carbon-coated nickel oxide material, denoted as S7, was obtained. The morphology was observed using a scanning electron microscope. Figure 2 Similarly, transmission electron microscopy is used to observe structures and Figure 3 Similarly, it can be seen that the size of the formed core-shell structure is approximately 50-100 nm, with the inner black layer being metallic NiO and the outer layer being a carbon layer, and the metal dispersion is relatively uniform. The specific surface area of ​​the composite material, as determined by BET analysis, is 99.5 m². 2 / g.

[0096] Example 8

[0097] The method of Example 6 was followed, except that the carbonization temperature was 900°C and the carbonization time was 4 hours, resulting in carbon-coated nickel oxide material, denoted as S8.

[0098] Observation using a scanning electron microscope, such as Figure 4 As shown, the overall structure of the sample is quite fragmented, and a spherical structure is no longer clearly observable. The specific surface area of ​​the composite material, as determined by BET testing, is 211.023 m². 2 / g.

[0099] Example 9

[0100] Water-soluble sulfonated bitumen was prepared according to the method in Example 1.

[0101] Water-soluble sulfonated asphalt and nickel acetate are dissolved in deionized water. The mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated asphalt (calculated as C) is 60:100. The mixture is stirred and heated at 80°C for three hours. After heating, the deionized water is removed by rotary evaporation. The mixture is then dried in an oven at 80°C for 12 hours to obtain the SP-Ni composite material.

[0102] A certain amount of SP-Ni composite material was placed in a tube furnace and heated to 900℃ at a rate of 10℃ / min under a N2 atmosphere, and then held at 900℃ for 2 hours. Afterwards, it was allowed to cool naturally in a nitrogen atmosphere. Once cooling was complete, the product was washed with 1 mol / L hydrochloric acid at 80℃ for 6 hours, and then washed with deionized water until neutral. Finally, the carbon material was dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S9.

[0103] Observation using a scanning electron microscope, such as Figure 5 As shown, the composite material exhibits a flaky and partially fragmented spherical structure. The specific surface area of ​​the composite material, as determined by BET analysis, is 185.79 m². 2 / g.

[0104] Example 10

[0105] The method of Example 1 was followed, except that the carbonization temperature was 900°C and the carbonization time was 2 hours, resulting in carbon-coated nickel oxide material, denoted as S10.

[0106] Example 11

[0107] Sulfonated bitumen was dissolved in distilled water at a concentration of 50 g / 100 mL. The solution was heated at 80°C for three hours. After heating, the liquid was collected by centrifugation. The collected liquid was then rotary evaporated to remove the water, yielding water-soluble sulfonated bitumen. The residual carbon content of this water-soluble sulfonated bitumen after carbonization at 800°C was 67 wt%.

[0108] Water-soluble sulfonated asphalt and nickel chloride were dissolved in deionized water. The mass ratio of nickel chloride (calculated as Ni) to water-soluble sulfonated asphalt (calculated as C) was 70:100. The mixture was stirred and heated at 80°C for three hours. After heating, the deionized water was removed by rotary evaporation. The mixture was then dried in an oven at 80°C for 12 hours to obtain the SP-NiCl2 composite material.

[0109] A certain amount of SP-NiCl2 composite material was placed in a tube furnace and heated to 800℃ at a rate of 10℃ / min under a N2 atmosphere, and then held at 800℃ for 2 hours. Afterwards, it was allowed to cool naturally in a nitrogen atmosphere. Once cooled, the resulting carbon material was washed with 1 mol / L hydrochloric acid at 80℃ for 12 hours, then washed with deionized water until neutral. Finally, the carbon material was dried in an oven at 80℃ for 12 hours to obtain the carbon-metal composite material, denoted as S11.

[0110] Comparative Example 1

[0111] The method of Example 1 was followed, except that sulfonated asphalt was directly replaced with sulfonated asphalt. A carbon-metal composite material, denoted as DS1, was obtained.

[0112] Performance Characterization

[0113] The ORR catalytic activity of the obtained carbon-coated material was tested using an electrochemical workstation. The test environment was a freshly prepared 0.1 mol / L KOH solution. The electrode slurry was prepared with 5 mg of catalyst, 10 μL of Nafion solution, and 500 μL of ethanol. During the test, the catalyst loading in the electrode was 0.42 mg / cm³. 2 The test results are shown in Table 1.

[0114] The LSV curves of the ORR reaction of the composite catalysts prepared in Examples 1, 2, 4 and 7 are shown below. Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown.

[0115] Table 1

[0116] Example number Half-wave potential (V) <![CDATA[Limiting current density (mA / cm 2 )]]> Average number of transferred electrons Example 1 0.81 6 Example 2 0.81 6 3.39 Example 3 0.77 4.2 Example 4 0.76 4.69 3.68 Example 5 0.78 7 Example 6 0.65 1 Example 7 0.72 3.1 Example 8 0.71 3.5 Example 9 0.7 2.89 Example 10 0.73 3.8 Example 11 0.64 1.2 Comparative Example 1 0.51 1

[0117] As can be seen from the results in Table 1, the carbon metal composite material prepared by the method provided in this invention has a high half-wave potential and a high limiting current density, as well as a high average number of transferred electrons, indicating that it has excellent electrochemical performance.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a carbon-metal composite material, characterized in that, Includes the following steps: (1) Mix water-soluble sulfonated asphalt, nickel salt and solvent, then remove the solvent to obtain the precursor; The residual carbon content of the water-soluble sulfonated asphalt after carbonization at 800℃ is not less than 50wt%. (2) The precursor is subjected to carbonization treatment; (3) The product obtained by carbonization is acid washed.

2. The preparation method according to claim 1, wherein, The residual carbon content of the water-soluble sulfonated asphalt carbonized at 800°C is 50-70 wt%, preferably 60-65 wt%.

3. The preparation method according to claim 1 or 2, wherein, The method for preparing the water-soluble sulfonated asphalt includes: dissolving the sulfonated asphalt in water under heating conditions, and then performing solid-liquid separation; Preferably, in the sulfonated asphalt, the content of C element is 65-75 wt%, preferably 70-73 wt%, the content of O element is 20-30 wt%, preferably 24-28 wt%, the content of N element is 0.6-2 wt%, preferably 1-1.5 wt%, and the content of S element is 0.2-1.5 wt%, preferably 0.5-1 wt%. Preferably, the amount of sulfonated bitumen used is 10-15g relative to 100mL of water; Preferably, the heating temperature is 60-80℃ and the heating time is 1-4h.

4. The preparation method according to any one of claims 1-3, wherein, The nickel salt is selected from nickel chloride and / or nickel acetate; Preferably, the mass ratio of the nickel salt (calculated as Ni) to the water-soluble sulfonated bitumen (calculated as C) is (50-90):100, more preferably (70-80):100; Preferably, in step (1), the mixing is carried out under stirring conditions, the mixing temperature is 65-75℃, and the mixing time is 1-2 hours; Preferably, the solvent is water.

5. The preparation method according to any one of claims 1-4, wherein, The carbonization process is carried out under an inert atmosphere, which is provided by nitrogen and / or argon. Preferably, the carbonization conditions include: a temperature of 500-1000℃, more preferably 600-900℃, a time of 1-4h, more preferably 2-3h, and a heating rate of 5-10℃ / min, more preferably 6-8℃ / min.

6. The preparation method according to any one of claims 1-5, wherein, The pickling process includes: contacting the product obtained from the carbonization treatment with an aqueous solution of acid, followed by washing and drying; Preferably, the acid is hydrochloric acid; Preferably, the concentration of the aqueous solution of the acid is 1-6 mol / L; Preferably, the contact temperature is 20-60℃ and the contact time is 1-4h.

7. The carbon metal composite material prepared by the preparation method according to any one of claims 1-6.

8. The carbon metal composite material according to claim 7, wherein, The carbon-metal composite material includes nickel oxide and graphitized carbon coated on the surface of nickel oxide. Preferably, in the carbon metal composite material, the mass ratio of Ni to C is (50-90):100, more preferably (70-80):

100.

9. The carbon metal composite material according to claim 7 or 8, wherein, The specific surface area of ​​the carbon metal composite material is 90-1000 m². 2 / g; Preferably, the carbon metal composite material has a spherical structure with a particle size of 50-100 nm.

10. The application of the carbon metal composite material according to any one of claims 7-9 in the electrocatalytic oxygen reduction reaction.

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