A method for preparing a self-supporting, pore-structure-adjustable, metal-ordered-distribution, three-dimensional electrocatalyst
By using the ice template method and calcination temperature control, a self-supporting three-dimensional electrocatalyst with tunable pore structure was prepared, solving the problems of high cost and poor stability of existing catalysts and achieving low-cost and high-efficiency hydrogen production through water electrolysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF PETROLEUM (BEIJING)
- Filing Date
- 2024-10-24
- Publication Date
- 2026-07-07
AI Technical Summary
Existing HER catalysts suffer from limited reserves of precious metals, high costs, insufficient activity of non-metallic catalysts, and difficulty in controlling the structure of support materials, resulting in poor long-term stability of the catalysts and making it difficult to meet industrial needs.
Porous organic polymers were prepared by ice template method, and the freezing direction and reaction monomer type were controlled to achieve directional, ordered and uniform distribution of metal nanoparticles on or inside the support. The conductivity and mechanical strength of the support were controlled by calcination temperature to prepare a self-supporting three-dimensional electrocatalyst with tunable pore structure.
The catalyst achieves low cost, high efficiency, and good long-term stability. By doping with non-precious metals, the cost is reduced, the metal adsorption sites and active centers are increased, and the catalytic performance is significantly improved, making it suitable for hydrogen production by water electrolysis.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst. Background Technology
[0002] With societal development, while traditional energy sources have brought economic prosperity, they have also caused serious environmental pollution problems, hindering the sustainable development of human society. To address these issues, the development of new energy sources has become a research hotspot. Hydrogen, as an ideal energy source, possesses advantages such as high calorific value and green, pollution-free combustion products, attracting widespread attention worldwide. However, currently, the vast majority of hydrogen production in China still heavily relies on industrial plants using fossil fuels, such as coal-to-hydrogen, natural gas-to-hydrogen, and industrial by-product hydrogen. Although these traditional industrial plants have simple hydrogen production processes, the resulting hydrogen has low purity and produces large amounts of the greenhouse gas CO2, failing to meet the requirements of today's green industrial development. Hydrogen production via water electrolysis (HER) does not rely on fossil fuels, using only water as a primary raw material; the equipment is simple, the system is mature, and it has promising industrialization prospects; it can be combined with new energy sources such as photovoltaics and wind power, and can serve as an energy storage method for new energy power and an intermediate carrier for energy conversion, making it one of the important pathways for clean energy conversion.
[0003] In the HER process, the development of electrocatalysts is crucial. Currently, HER catalysts are mainly classified into three categories: noble metal-based catalysts, transition metal-based catalysts, and non-metallic catalysts. Among them, noble metal catalysts exhibit significantly superior performance in HER catalysis; however, due to the limited reserves and high prices of noble metals, industrial application costs are substantial. To reduce costs, there has been extensive research on alternatives using non-metallic or transition metal-based catalysts. Non-metallic catalysts are primarily carbon materials, which possess advantages such as excellent conductivity, strong resistance to acid and alkali corrosion, and tunable structure. However, the intrinsic activity of carbon materials in catalytic water electrolysis for hydrogen evolution cannot meet the demands of industrial applications. Methods such as doping with non-metals like B, N, P, and S, or creating defects, are generally used to improve the catalytic activity of carbon materials to some extent, but the performance improvement remains very limited. Transition metal-based catalysts are generally prepared using metals or metal alloys such as Fe, Co, Ni, Mn, and Mo as the active center, supported on carriers such as nickel foam, porous carbon materials, and layered hydrogen hydroxides (LDHs). These catalysts offer advantages such as simple preparation methods, low cost, and tunable structure and composition. However, controlling the structure, pore size, and surface properties of the support material is extremely difficult, resulting in weak interactions between the metal active centers and the support, and the long-term stability of the catalyst needs further improvement. Therefore, the development of a low-cost, high-efficiency electrocatalyst with good long-term stability is urgently needed. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing a self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst. This method allows for precise control of pore size and structure by adjusting the proportion of raw materials and changing the freezing direction, meeting diverse application requirements. It also allows for the regulation of internal and external surface properties by changing the type of reactants, achieving directional, ordered, and uniform distribution of metal nanoparticles on or within the surface. Furthermore, by altering the calcination temperature of the support, the conductivity, defect quantity and type, and mechanical strength of the final prepared three-dimensional, self-supporting, porous carbon support can be controlled. This method exhibits good scalability and is easily doped with different metals and metal combinations. Doping with non-noble metals reduces the proportion of noble metals, thereby lowering the catalyst cost, while also increasing the metal adsorption sites and active centers of the catalyst.
[0005] The preparation method of the self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalyst provided by this invention is divided into the following two methods depending on the different steps of adding metal nanoparticles or metal precursors.
[0006] Method 1:
[0007] 1) Porous organic polymers were prepared using the ice template method;
[0008] 2) Dissolve the metal precursor in an ethanol solution at room temperature and mix it with the porous organic polymer support obtained in step 1). Stir for 22 to 26 hours and let stand until the ethanol is completely evaporated to obtain a porous organic polymer with ordered metal distribution.
[0009] 3) The porous organic polymer with ordered metal distribution obtained in step 2) is subjected to high-temperature carbonization to obtain the self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst.
[0010] In step 1) of method one, the method for preparing the porous organic polymer specifically includes the following steps: preparing a polymer precursor emulsion, wherein the emulsion includes a reactive monomer, a redox initiator, a crosslinking agent, and a reactive emulsifier; freezing the polymer precursor emulsion at low temperature; after freezing, polymerizing the frozen sample at low temperature; and after polymerization is completed, freeze-drying the frozen sample to remove the ice template to obtain the porous organic polymer.
[0011] Further, the reactive monomer may be selected from at least one of the following: methyl methacrylate (MMA), acrylonitrile (AN), methacrylamide (MAM), and butyl acrylate (BA); according to an embodiment of the present invention, the reactive monomer may be selected from: methyl methacrylate (MMA) and acrylonitrile (AN);
[0012] Furthermore, the redox initiator includes benzoyl peroxide (BPO) and N,N-dimethylaniline (DMA).
[0013] Furthermore, the crosslinking agent may be selected from ethylene glycol dimethacrylate (EGDMA).
[0014] Furthermore, the reactive emulsifier can be selected from the ADEKAREASOAP series, ER-10.
[0015] Furthermore, the cryogenic freezing process can be achieved by cooling with liquid nitrogen until the desired shape is formed.
[0016] Furthermore, the reaction conditions for the low-temperature polymerization are: low-temperature polymerization at -15℃ to -30℃ for at least 12 hours. Under these low-temperature polymerization conditions, the monomer droplets are completely coalesced and freeze-polymerized.
[0017] According to one embodiment of the present invention, the method for preparing the porous organic polymer is as follows: 0.075 g of BPO (benzoyl peroxide, the amount corresponding to a total emulsion volume of 10 mL) and 5% v / v (percentage of total emulsion volume) of EGDMA (ethylene glycol dimethacrylate) are mixed and then mixed with 15% v / v (percentage of total emulsion volume) of monomer (MMA:AN = 1:1, v / v; MMA: methyl methacrylate, AN: acrylonitrile) to form a monomer phase (20% v / v of the total emulsion volume); ER-10 emulsifier is prepared with water to form a 5% v / v (percentage of aqueous phase volume) ER-10 solution as the aqueous phase. The monomer phase and the aqueous phase are mixed at a volume ratio of 2:8 to form a precursor emulsion, and sonicated for 5 minutes (ensuring the emulsion is cooled to below 4°C before use). After sonication, 5% v / v (by total emulsion volume) of DMA (N,N-dimethylaniline) was added to the emulsion. After vigorous stirring for 1 minute, the mixture was immediately poured into a mold and cooled with liquid nitrogen until it solidified. The frozen sample was then placed at -15°C for at least 12 hours for cryogenic polymerization. Once polymerization was complete, the frozen sample was freeze-dried to remove the ice template, yielding a porous organic polymer.
[0018] In step 2) of method one, as ethanol evaporates, the metal sol gradually concentrates, eventually forming a gel of metal particles or metal oxide particles deposited on the carrier surface. The size and distribution of the metal particles or metal oxide particles are controlled by adjusting the ethanol evaporation rate and the stirring rate during the reaction, thereby achieving control over the loaded metal.
[0019] Furthermore, in step 2), the volume fraction of ethanol in the ethanol solution is 90-99.9%.
[0020] Furthermore, in step 2), the concentration of the metal precursor in the ethanol solution is 8 mg / L-50 mg / L.
[0021] In step 3) of method one, the high-temperature carbonization conditions can be as follows: heating at a rate of 2-5°C / min under a nitrogen atmosphere, raising the temperature to 700-800°C and holding for 2 hours. The organic ligands in the polymer material pyrolyze at high temperature, forming a carbonaceous porous structure. These porous structures provide excellent proton and electron transport channels, which is beneficial for the catalytic reaction. Simultaneously, at high temperature, metal ions are reduced to metal nanoparticles. These metal nanoparticles have good dispersion in the carbonaceous porous structure and can participate in the catalytic reaction as active catalyst centers, resulting in the final material after carbonization. Controlling the calcination temperature can regulate the electrical conductivity and mechanical strength of the material.
[0022] Method 2:
[0023] a) A porous organic polymer with ordered metal distribution was prepared using the ice template method;
[0024] b) The porous organic polymer with ordered metal distribution obtained in step a) is subjected to high-temperature carbonization to obtain the self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst.
[0025] a) In the process of preparing the emulsion, metal nanoparticles or metal precursors are directly added and mixed evenly with the emulsion before being frozen at low temperature. By controlling the amount and type of metal nanoparticles or metal precursors added, the uniform distribution of different metals on the carrier can be achieved.
[0026] In step a) of method two, the method for preparing a porous organic polymer with ordered metal distribution specifically includes the following steps: preparing a polymer precursor emulsion, wherein the emulsion includes a reactive monomer, a redox initiator, a crosslinking agent, a reactive emulsifier, metal nanoparticles or a metal precursor; freezing the polymer precursor emulsion at low temperature; after freezing, polymerizing the frozen sample at low temperature; after polymerization is completed, freeze-drying the frozen sample to remove the ice template, thereby obtaining a porous organic polymer with ordered metal distribution.
[0027] Further, the reactive monomer may be selected from at least one of the following: methyl methacrylate (MMA), acrylonitrile (AN), methacrylamide (MAM), and butyl acrylate (BA); according to an embodiment of the present invention, the reactive monomer may be selected from: methyl methacrylate (MMA) and acrylonitrile (AN);
[0028] Furthermore, the redox initiator includes benzoyl peroxide (BPO) and N,N-dimethylaniline (DMA).
[0029] Furthermore, the crosslinking agent may be selected from ethylene glycol dimethacrylate (EGDMA).
[0030] Furthermore, the reactive emulsifier can be selected from the ADEKAREASOAP series, ER-10.
[0031] Further, the metal nanoparticles or metal precursor are selected from at least one of the following: nickel chloride, cobalt chloride, gallium chloride, rubidium chloride, and ruthenium trichloride. The concentration of the metal nanoparticles or metal precursor in the ethanol solution is 8 mg / L-50 mg / L.
[0032] Furthermore, the cryogenic freezing process can be achieved by cooling with liquid nitrogen until the desired shape is formed.
[0033] Furthermore, the reaction conditions for the low-temperature polymerization are: low-temperature polymerization at -15℃ to -30℃ for at least 12 hours. Under these low-temperature polymerization conditions, the monomer droplets are completely coalesced and freeze-polymerized.
[0034] According to one embodiment of the present invention, a specific method for preparing a porous organic polymer with ordered metal distribution is as follows:
[0035] 0.075g of BPO (benzoyl peroxide, corresponding to a total emulsion volume of 10mL) and 5% v / v (percentage of total emulsion volume) of EGDMA (ethylene glycol dimethacrylate) were mixed with 15% v / v (percentage of total emulsion volume) of monomer (MMA:AN = 1:1, v / v; MMA: methyl methacrylate, AN: acrylonitrile) to form a monomer phase (20% v / v of the total emulsion volume); ER-10 emulsifier was prepared with water to form a 5% v / v (percentage of the aqueous phase volume) ER-10 solution as the aqueous phase. The monomer phase and aqueous phase were mixed at a volume ratio of 2:8 to form a precursor emulsion, and sonicated for 5 minutes (ensure the emulsion is cooled to below 4°C before use). After sonication, 5% v / v (by total emulsion volume) of DMA (N,N-dimethylaniline) and 10% v / v (by total emulsion volume) of an ethanol solution containing a metal precursor at a concentration of 8 mg / L–50 mg / L were added to the emulsion. The mixture was vigorously stirred for 1 minute, then immediately poured into a mold and cooled with liquid nitrogen until solidified. After solidification, the frozen sample was placed at -15°C for at least 12 hours for cryogenic polymerization. Once polymerization was complete, the frozen sample was freeze-dried to remove the ice template, yielding a porous organic polymer with an ordered metal distribution.
[0036] In step b) of method two, the high-temperature carbonization conditions can be heating at a rate of 2-5°C / min under a nitrogen atmosphere, raising the temperature to 700-800°C and holding for 2 hours. The organic ligands in the polymer material pyrolyze at high temperature, forming a carbonaceous porous structure. These porous structures provide excellent proton and electron transport channels, which is beneficial for the catalytic reaction. Simultaneously, at high temperature, metal ions are reduced to metal nanoparticles. These metal nanoparticles have good dispersion in the carbonaceous porous structure and can participate in the catalytic reaction as active catalyst centers, resulting in the final material after carbonization. Controlling the calcination temperature can regulate the electrical conductivity and mechanical strength of the material.
[0037] The self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalytic hydrogen production catalyst prepared by the above method also fall within the scope of protection of this invention.
[0038] This invention also provides applications of the aforementioned self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalyst.
[0039] The application is the use of self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalysts in hydrogen production via water electrolysis.
[0040] The present invention also provides a method for producing hydrogen by electrolysis of water.
[0041] The method for producing hydrogen by electrolysis of water provided by the present invention uses the self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalyst prepared by the present invention as an electrocatalyst.
[0042] Compared with the prior art, the present invention has the following beneficial effects:
[0043] 1. This method, in the preparation of porous materials, can achieve precise control over pore size and pore structure by controlling the direction and morphology of ice crystal growth and optimizing the concentration, ratio, and freezing process of initiators, crosslinking agents, and emulsifiers. This facilitates contact between materials and reactive sites and mass transfer during the catalytic process.
[0044] 2. By changing the type of reactive monomers, the internal and external surface properties can be controlled to achieve the directional, ordered, and uniform distribution of metal nanoparticles on or inside the surface; by changing the calcination temperature of the support, the conductivity, defect number and type, and mechanical strength of the finally prepared three-dimensional, self-supporting, porous carbon support can be controlled.
[0045] 3. This method has good scalability, easily allowing for the doping of different metals and metal combinations, facilitating the preparation of bimetallic or even multimetallic ordered three-dimensional materials. By doping with non-noble metals to reduce the proportion of noble metals, the cost of the catalyst can be lowered. Furthermore, by controlling the type of metal nanoparticles and their bonding forces with the support, the metal adsorption sites and active centers of the catalyst can be improved, ultimately achieving the development of low-cost, high-efficiency catalysts with good long-term stability.
[0046] 4. This method uses ice as a template, which reduces the generation of chemical waste such as organic solvents and is more environmentally friendly.
[0047] 5. Porous organic polymer materials can be copolymerized or have functional fillers (such as magnetic particles, conductive fillers, etc.) added to expand their applications in other fields such as catalysis, composite material modification, and supercapacitors. Attached Figure Description
[0048] Figure 1 The principle of low-temperature emulsion polymerization is as follows: a) the reaction principle of reacting monomers and emulsifiers; b) the initiation process of the redox-initiated system. The initial reaction occurs between oxidized BPO and DMA. The products of this reaction are unstable and readily generate free radicals at low temperatures, initiating the polymerization process.
[0049] Figure 2 ab) Controlled freezing of monomer / water emulsion: ice crystals grow continuously, and monomer droplets are discharged accordingly; cd) Placing the sample below -15°C for coalescence and low-temperature polymerization, c) coalescence, d) low-temperature polymerization; e) freeze drying to obtain the precursor; f) material carbonization.
[0050] Figure 3 This is a schematic diagram of the HER catalyst synthesis process (Method 1).
[0051] Figure 4 The images show cross-sectional scanning electron microscope (SEM) images of the porous polymer precursor materials prepared by method one (left side) and method two (right side) in the examples.
[0052] Figure 5 The image shows the EDS values of C, N, O, and Ru for the catalyst obtained after carbonization according to Method 1 in the examples.
[0053] Figure 6 The image shows the EDS values of C, N, O, and Ru for the catalyst obtained after carbonization according to method two in the examples.
[0054] Figure 7 The HER catalytic activities of Ru / NC, Ru / C, Ru / XC72C, Pt / C, and NC are shown in the following figures: (a) Linear voltammetric scan (LSV) curves; (b) Tafel curves and Tafel slopes; (c) Nernquist impedance diagrams; and (d) Comparison of active areas.
[0055] Figure 8 The results of the 1500-minute stability test of the HER catalyst (Ru / NC) prepared by method two in the examples are shown. Detailed Implementation
[0056] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.
[0057] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.
[0058] Example
[0059] 1. Synthesis of HER catalysts (Method 1)
[0060] 1) Mix 0.075g BPO (benzoyl peroxide, corresponding to a total emulsion volume of 10mL) and 5% v / v (total emulsion volume percentage) EGDMA (ethylene glycol dimethacrylate), then mix with 15% v / v (total emulsion volume percentage) monomer (MMA:AN = 1:1, v / v; MMA: methyl methacrylate, AN: acrylonitrile) to form a monomer phase (total emulsion volume percentage 20% v / v); prepare an ER-10 emulsifier solution with water to form a 5% v / v (total aqueous phase volume percentage) ER-10 solution as the aqueous phase. Mix the monomer phase and aqueous phase at a 2:8 volume ratio to form a precursor emulsion (10mL), and sonicate for 5 minutes (ensure the emulsion is cooled to below 4°C before use). After sonication, add 5% v / v (total emulsion volume percentage) DMA (N,N-dimethylaniline) to the emulsion, stir vigorously for 1 minute, and immediately pour into a mold. Cool with liquid nitrogen until set. After molding, the frozen sample was placed in a -15°C environment for low-temperature polymerization for at least 12 hours. After polymerization was complete, the frozen sample was freeze-dried to remove the ice template, yielding a porous organic polymer.
[0061] 2) 1.0 g of the porous organic polymer precursor was impregnated in ethanol solutions containing different amounts of ruthenium trichloride (2.2 mg, 6.6 mg, and 11 mg) (ruthenium trichloride concentrations were 8.8 mg / L, 26.4 mg / L, and 44 mg / L, respectively). After stirring for 24 h, the mixture was allowed to stand until the ethanol completely evaporated to obtain a porous organic polymer with an ordered metal distribution. Finally, the obtained polymer was placed in a tube furnace and heated at 750 °C for 2 h under a nitrogen atmosphere with a heating rate of 5 °C / min to obtain the final HER catalyst.
[0062] 2. Synthesis of HER catalysts (Method 2)
[0063] In the process of preparing the emulsion using the above method one, metal nanoparticles or metal precursors are directly added and mixed evenly with the emulsion before being frozen at low temperature. By controlling the amount and type of metal nanoparticles or metal precursors added, the uniform distribution of different metals on the carrier can be achieved.
[0064] The specific method is as follows:
[0065] a) Mix 0.075g BPO (benzoyl peroxide, corresponding to a total emulsion volume of 10mL) and 5% v / v (total emulsion volume percentage) EGDMA (ethylene glycol dimethacrylate), then mix with 15% v / v (total emulsion volume percentage) monomer (MMA:AN = 1:1, v / v; MMA: methyl methacrylate, AN: acrylonitrile) to form a monomer phase (total emulsion volume percentage 20% v / v); prepare an ER-10 emulsifier solution with water to form a 5% v / v (total aqueous phase volume percentage) ER-10 solution as the aqueous phase. Mix the monomer phase and aqueous phase at a 2:8 volume ratio to form a precursor emulsion (10mL), and sonicate for 5 minutes (ensure the emulsion is cooled to below 4°C before use). After sonication, 5% v / v (by total emulsion volume) of DMA (N,N-dimethylaniline) and 10% v / v (by total emulsion volume) of metal precursor ethanol solutions (concentrations of 8.8 mg / L, 26.4 mg / L, and 44 mg / L, respectively) were added to the emulsion. The mixture was vigorously stirred for 1 minute and immediately poured into a mold, then cooled with liquid nitrogen until solidified. After solidification, the frozen sample was placed at -15°C for at least 12 hours for cryogenic polymerization. Once polymerization was complete, the frozen sample was freeze-dried to remove the ice template, yielding a porous organic polymer with an ordered metal distribution.
[0066] b) The porous organic polymer with ordered metal distribution obtained in step a) is placed in a tube furnace and kept at 750°C for 2 hours under a nitrogen atmosphere. It is then heated at a heating rate of 5°C / min to obtain the final HER catalyst.
[0067] In the above preparation process, the pore size was controlled by adjusting the freezing temperature. A copper plate was used as the freezing surface, and liquid nitrogen was used as the cold source. The morphology of the resulting porous polymer precursor in the vertical direction is as follows: Figure 4 As shown. By Figure 4 It can be seen that the organic polymer material prepared by ice template forms longitudinal channels after the ice crystals are extracted, thus producing the desired porous organic polymer material.
[0068] By adjusting the emulsifier (ER-10) content to 0.1% v / v, 1% v / v, 5% v / v, and 10% v / v (all representing the volume percentage of the aqueous phase), emulsion droplets of different sizes were formed, thus affecting the strength of the polymer precursor. With a small amount of emulsifier (0.1% v / v), the emulsion droplets were large, making it difficult for them to drain and aggregate during ice growth, resulting in poor pore wall strength. Increasing the ER-10 concentration to 1% v / v resulted in a better emulsion, where these medium-sized droplets were effectively assembled into the pore walls; however, residual ice particles trapped within the monomer droplets caused defects within the pore walls. When the ER-10 concentration increased to 5% v / v, the emulsion droplets became smaller, and the droplets densely packed, avoiding defects in the final pore walls and exhibiting optimal compressive strength. At higher ER-10 concentrations (10% v / v), the self-polymerization of ER-10 led to weak areas in the pore walls and a decrease in compressive strength. Therefore, the ER-10 content is selected as 5% v / v.
[0069] When selecting the reactive monomer, if only methyl methacrylate (MMA) is used, there are fewer active sites. To achieve better hydrogen evolution performance, acrylonitrile (AN) is introduced, which increases the number of active sites and makes the metal nanoparticles more uniformly distributed.
[0070] Meanwhile, by changing the calcination temperature of the precursor, calcining at 700℃, 750℃, and 800℃, the precursor material calcined at 750℃ has better electrical conductivity, fewer defects, and the highest mechanical strength.
[0071] from Figure 5 As can be seen from the EDS-mapping diagram of Ru / NC prepared by Method 1, the catalyst bulk is mainly composed of C, with N elements uniformly distributed on the carbon framework, indicating successful doping of heteroatom nitrogen. In addition, a small amount of oxygen is present on the carbon support, which is due to residual oxygen caused by insufficient calcination temperature. Furthermore, the uniform distribution of Ru on the carbon support surface proves the successful loading of Ru nanoparticles.
[0072] from Figure 6As can be seen from the EDS-mapping diagram of Ru / NC prepared by method two, the catalyst is similar to that prepared by method one, mainly composed of C and O, with N elements uniformly distributed on the carbon framework, indicating successful doping of heteroatom nitrogen. Ru elements also show a uniform distribution on the carbon support surface, proving the successful loading of Ru nanoparticles.
[0073] 3. Electrocatalytic hydrogen production performance of HER catalysts
[0074] First, the electrochemical activity of Ru / NC (the catalyst obtained by impregnating 11 mg of ruthenium trichloride and doping with nitrogen in Example 1 and calcining at 750 °C), Ru / C, Ru / XC72C (XC72C is commercial carbon black, Vulcan XC 72), Pt / C (commercial platinum carbon, Aladdin Reagents Ltd.), and NC was tested.
[0075] The preparation method of Ru / C is basically the same as that of Ru / NC, except that acrylonitrile (AN) is replaced with an equal amount of methyl methacrylate (MMA).
[0076] The aforementioned Ru / XC72C uses XC72C as commercial carbon black to replace the porous organic polymer precursor in step 2) of method one above, and the rest of the preparation method is the same as step 2 of method one).
[0077] The aforementioned NC is a nitrogen-doped but unloaded porous carbon material, namely the porous organic polymer prepared in step 1) of the above method.
[0078] like Figure 7 As shown in (a), the NC sample exhibited almost no HER activity during hydrogen evolution, and the current density still failed to reach 10 mA / cm² even when the overpotential exceeded 500 mV. 2 This further illustrates that metallic Ru is the active site of the catalyst. Ru / C catalysts exhibit excellent electrochemical catalytic activity due to their high specific surface area and porous structure, even at low current densities (10 mA / cm²). 2 Under these conditions, it exhibited a hydrogen evolution activity of 40.2 mV. The Ru / NC catalyst, at 10 mA / cm², showed this activity. 2 and 50mA / cm 2 The HER performance at these times was 29.2 mV and 109.2 mV (lower overpotential is better), respectively, relative to the Ru / C catalyst η. 10 and η 50 These increased by 11 mV and 33 mV, respectively. Different carbon supports also significantly affected HER performance; a comparison of Ru / NC and Ru / N-XC72C revealed that Ru / N-XC72C had a higher η. 10 η 50The catalytic values were 110.2 mV and 266.2 mV, respectively, significantly lower than those of the Ru / NC catalyst, demonstrating the advantages of the prepared porous material. Its high specific surface area and abundant microporous and mesoporous structures provide ample space for metal active sites and excellent mass transfer performance.
[0079] Finally, the HER performance of Ru / NC and commercial Pt / C catalysts was compared at 10 mA / cm². 2 At the given current density, the commercial Pt / C catalyst exhibits an overpotential of 52.2 mV, which is much higher than that of the Ru / NC catalyst. In addition, the Ru / NC catalyst has a lower preparation cost and exhibits higher specific activity and economy, further demonstrating that the Ru / NC catalyst has the potential to replace the commercial Pt / C catalyst.
[0080] According to the LSV curve ( Figure 7 (b) The Tafel slope obtained from the analysis further reveals the kinetic performance of the Ru / NC (50.36 mV / dec), Ru / C (56.64 mV / dec), Ru / N-XC72C (111.47 mV / dec), Pt / C (51.15 mV / dec), and NC (835.5 mV / dec) catalysts. The Ru / NC catalyst exhibits a lower Tafel slope, follows the Volmer-Tafel mechanism, and possesses excellent kinetic performance.
[0081] Electrochemical impedance spectroscopy (EIS) further confirmed the advantages of the Ru / NC catalyst in terms of kinetic performance, such as... Figure 7 As shown in (c), the Ru / NC catalyst exhibits the lowest charge transfer resistance (Rct) at 39.96 Ω. In comparison with different carbon supports, Ru / N-XC72C shows a high impedance of 113.6 Ω, confirming that NC demonstrates superior electrical conductivity compared to commercial carbon black (XC72C). Finally, in the comparison between Ru / NC and the commercial Pt / C catalyst (Rct = 62.35 Ω), Ru / NC demonstrates superior electrical conductivity and HER catalytic performance.
[0082] Using the constant current chronopotential method, at 10mA / cm 2 The long-term stability of the Ru / NC catalyst was evaluated at a given current density. Figure 8 As shown, the Ru / NC catalyst exhibited excellent stability in 1M KOH electrolyte after continuous electrolysis for 1500 min, demonstrating its significant stability during alkaline hydrogen evolution. This high stability stems from the stable structure and excellent corrosion resistance of the support, as well as the confinement effect caused by the appropriate pore structure and pore size, which effectively inhibits austenitic ripening and limits the growth of Ru nanoparticles.
[0083] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.
Claims
1. A method for preparing a self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst, comprising the following steps: 1) Porous organic polymers were prepared using the ice template method; In step 1), the method for preparing the porous organic polymer specifically includes the following steps: preparing a polymer precursor emulsion, wherein the emulsion includes a reactive monomer, a redox initiator, a crosslinking agent, and a reactive emulsifier; freezing the polymer precursor emulsion at low temperature; after freezing, polymerizing the frozen sample at low temperature; after polymerization is completed, freeze-drying the frozen sample to remove the ice template to obtain the porous organic polymer. The reactive monomer is selected from at least one of the following: methyl methacrylate, acrylonitrile, methacrylamide, and butyl acrylate; The redox initiator includes benzoyl peroxide and N,N-dimethylaniline; The crosslinking agent is selected from ethylene glycol dimethacrylate; The reactive emulsifier is selected from the ADEKAREASOAP series ER-10; 2) Dissolve the metal precursor in an ethanol solution at room temperature and mix it with the porous organic polymer support obtained in step 1). After stirring, let it stand until the ethanol completely evaporates to obtain a porous organic polymer with an ordered distribution of metal precursor. The metal precursor is selected from ruthenium trichloride; 3) The porous organic polymer with ordered distribution of metal precursors obtained in step 2) is subjected to high-temperature carbonization to obtain the self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst.
2. The preparation method according to claim 1, characterized in that: In step 1), the cryogenic freezing process uses liquid nitrogen to cool the material until it is formed. The reaction conditions for the low-temperature polymerization are: low-temperature polymerization at -15℃ to -30℃ for at least 12 hours, under which monomer droplets are completely coalesced and frozen polymerized.
3. The preparation method according to claim 1 or 2, characterized in that: In step 2), the volume fraction of ethanol in the ethanol solution is 90-99.9%. And / or, in step 2), the concentration of the metal precursor in the ethanol solution is 8 mg / L-50 mg / L; And / or, in step 2), the stirring time is 22 to 26 hours.
4. The preparation method according to claim 1 or 2, characterized in that: In step 3), the conditions for high-temperature carbonization are as follows: under a nitrogen atmosphere, heating at a heating rate of 2-5℃ / min, heating to 700-800℃ and holding for 2 hours.
5. A method for preparing a self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst, comprising the following steps: a) A porous organic polymer with an ordered distribution of metal precursors was prepared using the ice template method; In step a), the method for preparing a porous organic polymer with an ordered distribution of metal precursors specifically includes the following steps: preparing a polymer precursor emulsion, wherein the emulsion includes a reactive monomer, a redox initiator, a crosslinking agent, a reactive emulsifier, and a metal precursor; freezing the polymer precursor emulsion at low temperature; after freezing, polymerizing the frozen sample at low temperature; after polymerization is completed, freeze-drying the frozen sample to remove the ice template, thereby obtaining a porous organic polymer with an ordered distribution of metal precursors. The reactive monomer is selected from at least one of the following: methyl methacrylate, acrylonitrile, methacrylamide, and butyl acrylate; The redox initiator includes benzoyl peroxide and N,N-dimethylaniline; The crosslinking agent is selected from ethylene glycol dimethacrylate; The reactive emulsifier is selected from the ADEKAREASOAP series ER-10; The metal precursor is selected from ruthenium trichloride; b) The porous organic polymer with ordered distribution of metal precursors obtained in step a) is subjected to high-temperature carbonization to obtain the self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst.
6. The preparation method according to claim 5, characterized in that: In step a), the cryogenic freezing process uses liquid nitrogen to cool the material until it is formed. The reaction conditions for the low-temperature polymerization are: low-temperature polymerization at -15℃ to -30℃ for at least 12 hours; under the conditions of the low-temperature polymerization, the monomer droplets are completely coalesced and frozen polymerized.
7. The preparation method according to claim 5 or 6, characterized in that: In step b), the conditions for high-temperature carbonization are as follows: heating at a rate of 2-5℃ / min under a nitrogen atmosphere, heating to 700-800℃ and holding for 2 hours.
8. A self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst prepared by the method of any one of claims 1-7.
9. The application of the self-supporting, tunable pore structure, ordered metal distribution, three-dimensional electrocatalyst as described in claim 8 in hydrogen production by water electrolysis.
10. A method for producing hydrogen by electrolysis of water, characterized in that: The method uses the self-supporting, tunable pore structure, ordered metal distribution, and three-dimensional electrocatalyst described in claim 8 as the electrocatalyst.