Doped hierarchically porous carbon material loaded with noble metal nanoparticles and method for preparing the same
Patent Information
- Application Number
- CN202510347808.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2026-09-25
AI Technical Summary
然而，贵金属纳米颗粒与碳材料之间若相互作用不足，则可能导致贵金属纳米颗粒的溶解、聚集及催化剂稳定性的问题
[0018]本发明制备的贵金属纳米材料具有如下特点：一步碳化活化法通过将碳化和活化整合为一个连续过程，简化了生产工艺，减少了操作步骤，并有效降低了生产成本；碱金属盐和(或)碱金属碱作为强氧化剂，在适当条件下能够显著促进碳化过程中的活化作用，相比传统活化剂(如磷酸或氯化锌)，其后处理更为简单，有助于减少二次污染；生物质来源丰富、价格低廉，降低了制备成本，通过适当的热处理过程可以实现无需额外添加剂的原位掺杂；微波辐射乙二醇法能够提供高能量，实现贵金属快速还原过程；微波辐射乙二醇法均匀加热方式使得贵金属颗粒在载体上粒径更小且分布更加均匀。
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Abstract
Description
Technical Field
[0001] This invention relates to doped hierarchical porous carbon materials loaded with noble metal nanoparticles and their preparation methods. The prepared noble metal nanoparticles have good catalytic effects on oxygen reduction reactions and belong to the field of advanced materials. Background Technology
[0002] With the depletion of fossil fuels and the deterioration of the ecological environment, the development of new, efficient, and sustainable clean energy sources has become increasingly urgent. Fuel cell technology, especially proton exchange membrane fuel cells (PEMFCs), is considered a key technology for future energy conversion due to its high energy conversion efficiency and low emissions. In these systems, the oxygen reduction reaction (ORR) is the main reaction at the cathode, and its efficiency directly determines the performance of the fuel cell. However, the slow kinetics of the ORR at the cathode lead to significant overpotential losses, which in turn affect the cell's output power and energy efficiency. Therefore, developing efficient and stable ORR catalysts to accelerate this process is crucial for improving the overall performance of PEMFCs. Noble metal nanomaterials are considered the best choice for ORR catalysts due to their high activity and stability, and are widely used in commercial PEMFCs. Noble metals have high electronic conductivity and good corrosion resistance, enabling efficient oxygen reduction at relatively low operating temperatures. However, the scarcity and high cost of noble metal resources have prompted researchers to seek alternative materials. Although research on non-noble metal nanomaterials has made some progress, they still cannot match the activity, stability, and durability of noble metal nanomaterials. Therefore, optimizing the structure and composition of noble metal nanomaterials to improve their performance and reduce costs remains an important research direction.
[0003] Dispersing noble metals on highly conductive and stable carbon supports not only reduces the amount of noble metals used, thus lowering costs, but also enhances electrocatalytic activity through the synergistic effect between carbon and noble metal nanomaterials. Porous carbon materials, due to their unique structural advantages—ultra-high specific surface area, abundant pore structure, and good mechanical and thermal stability—have become ideal electrocatalyst support materials, attracting widespread research attention. However, insufficient interaction between noble metal nanoparticles and carbon materials can lead to problems such as dissolution, aggregation of noble metal nanoparticles, and catalyst stability. To address these issues, scientists have introduced heteroatom doping (such as N, P, and S) to enhance the interaction between carbon supports and noble metal nanoparticles. Heteroatom doping can significantly alter the electronic properties of carbon materials, increase defect density, and provide additional chemically active sites and anchoring sites to immobilize noble metal nanoparticles. Simultaneously, it optimizes the electronic and structural properties of the catalyst, thereby enhancing its electrochemical performance.
[0004] Biomass refers to organic matter produced directly or indirectly through the life activities of organisms (such as plants, animals, and microorganisms), and is a major source of carbon production worldwide. In recent years, biomass materials have been widely studied due to their abundant resources, low cost, and environmental friendliness, making them a high-quality raw material for preparing porous carbon materials. Furthermore, naturally occurring heteroatoms in biomass raw materials (such as nitrogen, sulfur, and phosphorus) can be in-situ doped without additional additives through appropriate heat treatment processes, thereby endowing porous carbon materials with unique physicochemical properties. Summary of the Invention
[0005] Based on the above facts, this invention provides a doped hierarchical porous carbon material loaded with noble metal nanoparticles and its preparation method. This material has advantages such as simple preparation method, low cost, and good catalytic performance, providing a new approach for catalyzing oxygen reduction reactions.
[0006] As the first aspect, the doped hierarchical porous carbon material loaded with noble metal nanoparticles and its preparation method are described in the following steps:
[0007] Step 1: Preparation of doped hierarchical porous carbon materials;
[0008] Weigh 1–10 parts by weight of alkali metal salt and / or alkali metal alkali, and 1–10 parts by weight of biomass, and dissolve them in 5–100 parts by weight of distilled water. Stir mechanically at 0–85°C for 10–60 min. Cool to room temperature, wash the resulting material with distilled water, and then freeze-dry. Grind the freeze-dried sample and sieve it through a 50–500 mesh sieve. Carbonize in a tube furnace at a certain temperature under inert gas protection for 1–5 h, with a heating rate of 5–20°C / min. Wash the carbonized sample sequentially with 0.5–5 mol / L dilute hydrochloric acid, 5–20% hydrogen peroxide, and distilled water. Repeat this washing process 3–5 times until the supernatant is clear. Retain the black precipitate and vacuum dry at 40–80°C.
[0009] Step 2: Preparation of doped hierarchical porous carbon materials loaded with noble metal nanoparticles;
[0010] Noble metal nanoparticles were loaded using the microwave irradiation ethylene glycol method in a fully automated microwave synthesizer. The specific steps are as follows: In a 10–30 mL reactor, 10–50 mg of doped hierarchical porous carbon material, 5–15 mL of ethylene glycol, and 0–1 mL of noble metal solution (5–10 mg / mL) were added sequentially. The pH was adjusted to 9–11 using a 0–1 mol / L sodium hydroxide / ethylene glycol solution. The reaction temperature was 200–300 °C, and the reaction time was 10–30 min. After the reaction was complete, the mixture was cooled and centrifuged. The product was washed with anhydrous ethanol and distilled water, and then vacuum dried at 40–80 °C.
[0011] The alkali metal salts mentioned in step one include, but are not limited to, potassium permanganate, potassium carbonate, sodium bicarbonate, sodium chloride, and potassium chloride.
[0012] The alkali metal base mentioned in step one includes, but is not limited to, potassium hydroxide, sodium hydroxide, and cesium hydroxide.
[0013] The biomass mentioned in step one includes, but is not limited to, chitosan, chitin, cellulose, starch, sucrose, sulfonated lignin, and animal bones.
[0014] The carbonization temperature mentioned in step one is 500–1000℃.
[0015] The inert gases mentioned in step one include, but are not limited to, argon, nitrogen, and helium.
[0016] The precious metal solution mentioned in step two includes, but is not limited to, chloroplatinic acid solution, chloropalladic acid solution, chlororhodium acid solution, and silver nitrate solution.
[0017] The present invention has the following beneficial effects:
[0018] The noble metal nanomaterials prepared by this invention have the following characteristics: the one-step carbonization-activation method integrates carbonization and activation into a continuous process, simplifying the production process, reducing operation steps, and effectively lowering production costs; alkali metal salts and / or alkali metal bases, as strong oxidants, can significantly promote the activation effect during the carbonization process under appropriate conditions, and their post-processing is simpler than that of traditional activators (such as phosphoric acid or zinc chloride), which helps to reduce secondary pollution; biomass is abundant and inexpensive, reducing preparation costs, and in-situ doping without additional additives can be achieved through appropriate heat treatment; the microwave radiation ethylene glycol method can provide high energy to achieve a rapid reduction process of noble metals; the uniform heating method of the microwave radiation ethylene glycol method results in smaller particle size and more uniform distribution of noble metal particles on the carrier. Attached Figure Description
[0019] Figure 1 This is a transmission electron microscope (TEM) image of the doped hierarchical porous carbon material prepared in Example 1 of the present invention.
[0020] Figure 2 This is a transmission electron microscope (TEM) image of the doped hierarchical porous carbon material loaded with noble metal nanoparticles prepared in Example 1 of the present invention.
[0021] Figure 3 The linear sweep voltammetry (LSV) curve of the oxygen reduction reaction catalyzed by the noble metal nanomaterials prepared in Example 1 of this invention is shown.
[0022] Figure 4The hydrogen peroxide yield and average electron transfer number are obtained during the oxygen reduction reaction catalyzed by the noble metal nanomaterials prepared in Example 1 of this invention.
[0023] Figure 5 Accelerated durability tests were conducted on the noble metal nanomaterials and platinum-carbon catalyst prepared in Example 1 of this invention.
[0024] Figure 6 The methanol resistance performance of the noble metal nanomaterials and platinum-carbon catalyst prepared in Example 1 of this invention was tested. Detailed Implementation
[0025] The technical solution of the present invention will be further described in detail below through embodiments. Obviously, the described embodiments are only some embodiments of the present invention.
[0026] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and not for limiting the claims of the present invention.
[0027] Example 1:
[0028] Doped hierarchical porous carbon materials loaded with noble metal nanoparticles and their preparation methods:
[0029] 1 g of potassium permanganate was dissolved in 10 mL of distilled water and ultrasonically dispersed to form a homogeneous solution. Then, 1 g of chitosan (α-type configuration; degree of deacetylation ≥95%; molecular weight 50–300 kDa) was added to the solution and stirred with a magnetic stirrer at 85 °C for 30 minutes. After cooling to room temperature, the resulting material was washed with distilled water and then freeze-dried. The freeze-dried sample was ground and sieved through a 200-mesh sieve. The obtained product was carbonized in a tube furnace at 600 °C under argon protection for 2 hours at a heating rate of 10 °C / min. The product was washed sequentially with dilute hydrochloric acid (1 mol / L), hydrogen peroxide (5% by mass), and distilled water to remove any unreacted residual reagents. This washing process was repeated three times until the supernatant was clear. The black precipitate was retained and dried under vacuum at 60 °C to obtain a nitrogen-doped hierarchical porous carbon material, named CDHPM-600.
[0030] Noble metal nanoparticles were loaded onto the ethylene glycol using a microwave-irradiated method in a fully automated microwave synthesizer. The specific steps are as follows: In a 20 ml reactor, 50 mg of CDHPM-600, 15 mL of ethylene glycol, and 1 mL of chloroplatinic acid solution (10 mg / ml) were added sequentially. The pH was adjusted to 9 using a 1 mol / L sodium hydroxide / ethylene glycol solution. The reaction temperature was 200 °C, and the reaction time was 30 min. After the reaction was complete, the mixture was cooled and centrifuged. The product was washed with anhydrous ethanol and distilled water, and then vacuum dried at 60 °C to obtain a nitrogen-doped hierarchical porous carbon material loaded with noble metal nanoparticles, named Pt / CDHPM-600.
[0031] Example 2:
[0032] 2g of potassium hydroxide was dissolved in 20mL of distilled water and ultrasonically dispersed to form a homogeneous solution. Then, 2g of sulfonated lignin (side chain configuration; molecular weight 50–500 Da) was added to the solution, and the mixture was stirred at 80℃ for 40 minutes using a magnetic stirrer. After cooling to room temperature, the resulting material was washed with distilled water and then freeze-dried. The freeze-dried sample was ground and sieved through a 100-mesh sieve. The obtained product was carbonized in a tube furnace at 500℃ under nitrogen protection for 1 hour, with a heating rate of 8℃ / min. The product was washed sequentially with dilute hydrochloric acid (2mol / L), hydrogen peroxide (8% by mass), and distilled water to remove any unreacted residual reagents. This washing process was repeated four times until the supernatant was clear. The black precipitate was retained and dried under vacuum at 65℃ to obtain a sulfur-doped hierarchical porous carbon material.
[0033] Noble metal nanoparticles were loaded onto the ethylene glycol substrate using a microwave-irradiated method in a fully automated microwave synthesizer. The specific steps were as follows: In a 10 mL reactor, 30 mg of doped hierarchical porous carbon material, 10 mL of ethylene glycol, and 0.8 mL of chloropalladium acid solution (8 mg / mL) were added sequentially. The pH was adjusted to 10 using a 0.8 mol / L sodium hydroxide / ethylene glycol solution. The reaction temperature was 250 °C, and the reaction time was 25 min. After the reaction was complete, the substrate was cooled and centrifuged. The product was washed with anhydrous ethanol and distilled water, and then vacuum dried at 65 °C to obtain sulfur-doped hierarchical porous carbon material loaded with noble metal nanoparticles.
[0034] Example 3:
[0035] 3g of potassium carbonate was dissolved in 30mL of distilled water and ultrasonically dispersed to form a homogeneous solution. Then, 3g of fish bone powder was added to the solution, and the mixture was stirred at 75℃ for 30 minutes using a magnetic stirrer. After cooling to room temperature, the resulting material was washed with distilled water and then freeze-dried. The freeze-dried sample was ground and sieved through a 400-mesh sieve. The resulting product was carbonized in a tube furnace at 700℃ under argon protection for 3 hours at a heating rate of 5℃ / min. The product was washed sequentially with dilute hydrochloric acid (3mol / L), hydrogen peroxide (10% by mass), and distilled water to remove any unreacted residual reagents. This washing process was repeated 5 times until the supernatant was clear. The black precipitate was retained and dried under vacuum at 70℃ to obtain phosphorus-doped hierarchical porous carbon material.
[0036] Noble metal nanoparticles were loaded onto the ethylene glycol substrate using a microwave-irradiated method in a fully automated microwave synthesizer. The specific steps were as follows: In a 15°C reactor, 40 mg of doped hierarchical porous carbon material, 12 mL of ethylene glycol, and 0.5 mL of rhodium chloroester solution (5 mg / mL) were added sequentially. The pH was adjusted to 11 using a 0.5 mol / L sodium hydroxide / ethylene glycol solution. The reaction temperature was 300°C, and the reaction time was 20 min. After the reaction was complete, the substrate was cooled and centrifuged. The product was washed with anhydrous ethanol and distilled water, and then vacuum dried at 70°C to obtain phosphorus-doped hierarchical porous carbon material loaded with noble metal nanoparticles.
[0037] To further illustrate this noble metal nanomaterial, the present invention also includes the following morphological analysis of the noble metal nanomaterial and its application in catalytic oxygen reduction reactions.
[0038] 1. Morphological analysis
[0039] To visually observe the morphology of the doped hierarchical porous carbon material and noble metal nanomaterials prepared in this embodiment, Pt / CDHPM-600 was used as the observation object: the doped hierarchical porous carbon material and noble metal nanomaterials were dissolved in water to obtain a mixed solution, which was then dropped onto a copper grid, dried at 40°C, and imaged by TEM (JEM-2100(HR), 200KV). Figure 1 and Figure 2 The images shown are transmission electron microscopy (TEM) images of doped hierarchical porous carbon materials and noble metal nanomaterials; from... Figure 1 The prepared doped hierarchical porous carbon material exhibits a rich pore structure. The hierarchical porous system not only helps reduce mass transfer resistance but also increases the number of exposed active sites, thereby more effectively anchoring noble metal nanoparticles; from Figure 2 It can be observed that the platinum nanoparticles are uniformly distributed on the CDHPM-600 support, and no obvious aggregation phenomenon is observed, showing good dispersibility.
[0040] 2. Catalytic oxygen reduction reaction experiment
[0041] The catalytic oxygen reduction reaction performance of the noble metal nanomaterials prepared in Example 1 was verified, and the verification process is as follows:
[0042] (1) All electrochemical tests were performed on a CHI 760E electrochemical workstation using a three-electrode system. This three-electrode system consisted of a working electrode, a reference electrode, and a counter electrode. For ORR electrochemical measurements, a glassy carbon electrode served as the working electrode, a Pt ring as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The electrolyte was a 0.1 mol / L KOH solution. During testing, all electrode potentials were converted to the reversible hydrogen electrode potential, E0. (RHE) Calculations are performed based on the Nernst equation:
[0043] E (RHE) =E (Ag / AgCl) +0.0592 pH +0.197
[0044] (2) Preparation of working electrode: Weigh 5 mg of catalyst, add 950 μL of ethanol and 50 μL of Nafion solution, and sonicate for 30 min to disperse it evenly. Measure 5 μL of ink and drop it onto a clean glassy carbon electrode. Repeat twice. After the catalyst has dried naturally, it is used for testing. The theoretical catalyst loading is 2.5 mg / cm³. 2 .
[0045] (3) The actual platinum content in Pt / CDHPM-600 was 5.75% as determined by ICP-MS testing.
[0046] (4) ORR electrochemical measurement: Cyclic voltammetry was performed in O2-saturated 0.1M KOH solution with a potential window of 0–1.20 V (vs. RHE) and a scan rate of 50 mV / s until a stable CV curve was obtained (usually 50 cycles). In O2-saturated 0.1M KOH electrolyte, the linear sweep voltammetry (LSV) curve was recorded at a scan rate of 10 mV / s and a rotation speed of 1600 rpm. Figure 3 ).
[0047] (5) Hydrogen peroxide yield and average electron transfer number n of the catalyst in the ORR process Figure 4 According to RRDE measurements, the voltage of the Pt ring is 1.5V (vs. RHE), and the collection rate N is 0.37 (N refers to the proportion of reduced material rotated onto the ring electrode to the total reduced material generated on the disk electrode). The specific calculation formula is as follows:
[0048]
[0049] Among them, i d and i rThese are the absolute values of disk current density and ring current density, respectively.
[0050] (6) Accelerated Durability Testing (ADTs) and Methanol Resistance Testing: The potential was cycled 3000 times between 0.9 and 1.10 V in a saturated O2 electrolyte at a scan rate of 50 mV / s. The electrochemical activity of the catalyst was recorded before and after the tests. The LSV curves before and after 3000 scans were compared. Figure 5 The stability of the catalyst was evaluated by adding 3M methanol to a 0.1M KOH solution after 300 seconds to test the catalyst's resistance to methanol. Figure 6 ).
[0051] (7) Figure 3 The onset potential of Pt / CDHPM-600 is closest to that of 20% Pt / C, and its peak potential is the most positive. In the ORR catalytic reaction, a more positive onset potential means that the catalyst can trigger the oxygen reduction reaction more effectively. Pt / CDHPM-600 also has advantages over 20% Pt / C in terms of half-wave potential and limiting current density; for example... Figure 4 As shown, the Pt / CDHPM-600 catalyzes the oxygen reduction reaction with a low hydrogen peroxide yield and can efficiently achieve a four-electron transfer pathway.
[0052] (8) Figure 5 As shown, in an oxygen-saturated electrolyte, the limiting current density of Pt / CDHPM-600 changed significantly after 3000 CV scans, with a half-wave potential shifting negatively by only 2 mV. Under the same conditions, 20% Pt / C showed a 2.7 mV negative shift in half-wave potential and a larger change in limiting current density. This result indicates that Pt / CDHPM-600 exhibits better cycling stability than 20% Pt / C. Figure 6 As shown, in 0.1M KOH solution, after the addition of 3M methanol at 300 seconds, the 20% Pt / C catalyst exhibited a significant current response, while the Pt / CDHPM-600 showed a lower current response in contrast. This result demonstrates that Pt / CDHPM-600 possesses excellent methanol resistance.
Claims
1. Doped hierarchical porous carbon materials loaded with noble metal nanoparticles and their preparation method, the specific method is as follows: Step 1: Preparation of doped hierarchical porous carbon materials; Weigh 1–10 parts by weight of alkali metal salt and / or alkali metal alkali, and 1–10 parts by weight of biomass, and dissolve them in 5–100 parts by weight of distilled water. Stir mechanically at 0–85°C for 10–60 min. Cool to room temperature, wash the resulting material with distilled water, and then freeze-dry. Grind the freeze-dried sample and sieve it through a 50–500 mesh sieve. Carbonize in a tube furnace at a certain temperature under inert gas protection for 1–5 h, with a heating rate of 5–20°C / min. Wash the carbonized sample sequentially with 0.5–5 mol / L dilute hydrochloric acid, 5–20% hydrogen peroxide, and distilled water. Repeat this washing process 3–5 times until the supernatant is clear. Retain the black precipitate and vacuum dry at 40–80°C. Step 2: Preparation of doped hierarchical porous carbon materials loaded with noble metal nanoparticles; Noble metal nanoparticles were loaded using the microwave irradiation ethylene glycol method in a fully automated microwave synthesizer. The specific steps are as follows: In a 10–30 mL reactor, 10–50 mg of doped hierarchical porous carbon material, 5–15 mL of ethylene glycol, and 0–1 mL of noble metal solution (5–10 mg / mL) were added sequentially. The pH was adjusted to 9–11 using a 0–1 mol / L sodium hydroxide / ethylene glycol solution. The reaction temperature was 200–300 °C, and the reaction time was 10–30 min. After the reaction was complete, the mixture was cooled and centrifuged. The product was washed with anhydrous ethanol and distilled water, and then vacuum dried at 40–80 °C.
2. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The alkali metal salts mentioned in step one include, but are not limited to, potassium permanganate, potassium carbonate, sodium bicarbonate, sodium chloride, and potassium chloride.
3. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The alkali metal base mentioned in step one includes, but is not limited to, potassium hydroxide, sodium hydroxide, and cesium hydroxide.
4. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The biomass mentioned in step one includes, but is not limited to, chitosan, chitin, cellulose, starch, sucrose, sulfonated lignin, and animal bones.
5. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The carbonization temperature mentioned in step one is 500–1000℃.
6. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The inert gases mentioned in step one include, but are not limited to, argon, nitrogen, and helium.
7. The doped hierarchical porous carbon material loaded with noble metal nanoparticles according to claim 1 and its preparation method, characterized in that, The precious metal solution mentioned in step two includes, but is not limited to, chloroplatinic acid solution, chloropalladic acid solution, chlororhodium acid solution, and silver nitrate solution.