Self-standing transition metal armor catalyst and preparation method thereof
By introducing an inert protective layer and gallium-indium alloy nanocapsules into a self-standing transition metal armored catalyst, the structural collapse problem caused by the coordination adsorption of chloride ions at the catalyst's metal active sites was solved, thereby improving the catalyst's stability and activity. This makes the catalyst suitable for hydrogen production through water electrolysis and organic electro-oxidation reactions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-23
- Publication Date
- 2026-03-13
AI Technical Summary
Existing catalysts exhibit a strong tendency for coordination adsorption between their metal active sites and chloride ions, leading to catalyst structural collapse and affecting the stability and lifespan of electrode performance, particularly evident in seawater electrolysis for hydrogen production.
A self-standing transition metal armored catalyst is employed, which forms a core-shell composite structure by coating the active components of the three-dimensional micro-nano structure with an inert material protective layer. This structure includes a gradient protective layer and embedded gallium-indium alloy nanocapsules, thereby enhancing the catalyst's stability and corrosion resistance.
It effectively increases the active specific surface area of the catalyst, improves catalytic activity and durability, extends the service life of the catalyst, reduces the replacement frequency and cost, and is suitable for hydrogen production by water electrolysis and organic electro-oxidation reactions.
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Figure CN121648983A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to inorganic functional materials technology, specifically to a self-standing transition metal armor catalyst and its preparation method. Background Technology
[0002] Hydrogen production from water using renewable electricity is widely considered a key component in contributing to global carbon neutrality. However, the catalytic performance of existing catalytic electrodes has long been unsatisfactory. Most previous research has focused on optimizing the binding energy between the catalyst and reaction intermediates and maximizing the exposure of active sites. In fact, improving mass transfer kinetics remains a significant challenge for industrial electrolysis. This situation hinders the development of alkaline water electrolysis (AWE) because of the very limited electrode surface area and the use of membranes; bubble interference is the core issue limiting the mass transfer efficiency of water electrolysis systems, which is exponentially amplified under high current density conditions. Existing research techniques show that energy losses caused by bubble blockage on the electrode surface can account for more than 30% of the total energy loss of the system, a phenomenon that significantly reduces the energy conversion efficiency of water electrolysis systems.
[0003] To address the problem of bubble blockage on electrode surfaces, constructing self-standing electrodes with nanostructures has become a highly promising solution. For example, by designing micro / nano structures such as vertical arrays of nanosheets, multi-level nanotube networks, or nanowire forests, discretely distributed three-phase (solid-liquid-gas) contact lines can be formed on the electrode surface. This structural design achieves performance improvement through a dual mechanism: on the one hand, it effectively reduces bubble adhesion strength by optimizing surface energy and regulating Laplace pressure; on the other hand, it utilizes a stress dispersion mechanism to suppress concentration polarization caused by bubble volume surges while protecting the fine nanoporous structure of the catalyst surface, thus ensuring the long-term stable operation of the electrode. However, when this structure is applied to seawater electrolysis systems, chloride ions (Cl...)... - The catalyst exhibits a strong tendency for coordination adsorption at the active metal sites. This characteristic not only accelerates the chemical corrosion of the active metal sites but also causes the catalyst structure to collapse, ultimately leading to irreversible degradation of electrode performance. This has become a critical technical bottleneck restricting the development of direct seawater electrolysis for hydrogen production, necessitating the design of a catalyst material with strong corrosion resistance. Summary of the Invention
[0004] The purpose of this invention is to provide a self-standing transition metal armored catalyst and its preparation method, in order to solve the problem that in the prior art, the catalyst metal active sites have a strong tendency to coordinate adsorption with chloride ions, which will accelerate the chemical corrosion of the metal active sites, and will also cause the catalyst structure to collapse, ultimately leading to irreversible degradation of electrode performance.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a self-standing transition metal armored catalyst, which uses a self-standing active component with a three-dimensional micro-nano structure as the structural matrix and is covered with an inert material protective layer to form a core-shell composite structure. The self-standing active component with the three-dimensional micro-nano structure includes metal oxides, metal phosphides, metal sulfides and metal selenides, and the outer inert material protective layer includes a carbon layer and boron nitride.
[0006] Preferably, the morphology of the self-supporting active components of the three-dimensional micro / nano structure includes nanowires, nanoflowers, nanosea urchins, nanocorals, and nanoleaves.
[0007] Preferably, the morphology of the three-dimensional micro / nano structure of the self-standing active component is controllably prepared by using a nitrate raw material via a hydrothermal method or an electrodeposition method, and the nitrate raw material of the three-dimensional micro / nano structure of the self-standing active component is at least one of nickel nitrate, cobalt nitrate, and iron nitrate.
[0008] Preferably, the steps for preparing three-dimensional micro / nano structures using the hydrothermal method are as follows:
[0009] Nitrate, urea, and ammonium fluoride are used as raw materials;
[0010] Nitrate, urea, and ammonium fluoride are mixed in a predetermined stoichiometric ratio to form a mixed solution;
[0011] The mixed solution and the substrate material are placed together in a high-pressure reactor, and the active components are grown in situ on the substrate material through hydrothermal reaction.
[0012] Preferably, the step of preparing three-dimensional micro / nano active components by the electrodeposition method is as follows:
[0013] Nitrate solution was used as the raw material;
[0014] A three-electrode system was constructed by using the substrate material as the working electrode and platinum electrode and Hg / HgO electrode as the counter electrode and reference electrode.
[0015] Active components are formed by electrodeposition on the surface of the substrate material.
[0016] Preferably, the outer inert material protective layer further includes a gradient protective layer, wherein the gradient protective layer is provided with the following components from the inside out:
[0017] The highly conductive inner layer is composed of graphene or graphite carbon.
[0018] The insulating intermediate layer is composed of ultrathin boron nitride or titanium carbide;
[0019] The outer layer is selectively permeated and consists of microporous silica.
[0020] Preferably, the outer inert material protective layer contains embedded nanocapsules containing gallium-indium alloy.
[0021] Preferably, an interface layer composed of a monolayer silane coupling agent or a phosphorus- or sulfur-containing organic ligand is provided between the structural matrix and the outer inert material protective layer.
[0022] Preferably, the outer inert material protective layer is applied to the structural substrate in an in-situ assembled manner.
[0023] A method for preparing a self-standing transition metal armored catalyst, comprising the following steps:
[0024] Take the corresponding weights of nitrate, urea and ammonium fluoride according to the set stoichiometric ratio, and dissolve the nitrate, urea and ammonium fluoride in ultrasonic water by magnetic stirring to form a mixed solution;
[0025] The mixed solution and the substrate were transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 120–180 °C.
[0026] The substrate that had undergone hydrothermal reaction was washed alternately with ethanol and ultrapure water, and then vacuum dried to obtain a self-standing three-dimensional micro / nano structure precursor.
[0027] An appropriate amount of dimethylimidazole was dissolved in an aqueous methanol solution. The self-standing three-dimensional micro / nano structure precursor was then immersed in the dimethylimidazole and methanol solution for coordination self-assembly. After standing for several hours, a metal-organic framework coating layer was formed on the surface of the self-standing three-dimensional micro / nano structure precursor.
[0028] A self-standing three-dimensional micro / nano structure precursor with a metal-organic framework coating is calcined at 300–500 °C in an inert gas atmosphere to obtain a self-standing transition metal armor catalyst.
[0029] Compared with existing technologies, this invention provides a self-standing transition metal armored catalyst and its preparation method. This catalyst utilizes an inert material protective layer coated onto a three-dimensional micro / nanostructured self-standing active component matrix. This protective layer enhances the overall stability, anti-poisoning properties, and lifespan of the catalyst. Because the active component matrix is a self-standing three-dimensional micro / nanostructure, the active surface area is effectively increased. Combined with the physical barrier effect and electronic effect of the protective layer, it exhibits excellent catalytic activity and durability in water electrolysis for hydrogen production and organic electro-oxidation reactions. The preparation process of this catalyst features readily available raw materials, mild conditions, and good reproducibility, demonstrating promising prospects for industrial application. Attached Figure Description
[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.
[0031] Figure 1 This is a schematic diagram of the catalyst structure provided in an embodiment of the present invention;
[0032] Figure 2 This is a flowchart illustrating the catalyst preparation method provided in an embodiment of the present invention. Detailed Implementation
[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0034] As attached Figure 1 To be continued Figure 2 As shown:
[0035] Example:
[0036] This invention provides a self-standing transition metal armored catalyst and its preparation method. The catalyst uses a self-standing active component with a three-dimensional micro-nano structure as the structural matrix and is covered with an inert material protective layer to form a core-shell composite structure. The self-standing active component with the three-dimensional micro-nano structure includes metal oxides, metal phosphides, metal sulfides and metal selenides. The inert material protective layer includes a carbon layer and boron nitride.
[0037] This catalyst improves the overall stability, anti-poisoning performance, and service life of the catalyst by coating an inert material protective layer on the self-standing active component matrix of a three-dimensional micro-nano structure. Since the active component matrix is a self-standing three-dimensional micro-nano structure, it can effectively increase the active specific surface area. Combined with the physical barrier effect and electronic effect of the protective layer, it can exhibit excellent catalytic activity and durability in water electrolysis for hydrogen production and organic electro-oxidation reactions.
[0038] A method for preparing a self-standing transition metal armored catalyst, comprising the following steps:
[0039] Take the corresponding weights of nitrate, urea and ammonium fluoride according to the set stoichiometric ratio, and dissolve the nitrate, urea and ammonium fluoride in ultrasonic water by magnetic stirring to form a mixed solution;
[0040] The mixed solution and the substrate were transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 120–180 °C.
[0041] The substrate that had undergone hydrothermal reaction was washed alternately with ethanol and ultrapure water, and then vacuum dried to obtain a self-standing three-dimensional micro / nano structure precursor.
[0042] An appropriate amount of dimethylimidazole was dissolved in an aqueous methanol solution. The self-standing three-dimensional micro / nano structure precursor was then immersed in the dimethylimidazole and methanol solution for coordination self-assembly. After standing for several hours, a metal-organic framework coating layer was formed on the surface of the self-standing three-dimensional micro / nano structure precursor.
[0043] A self-standing three-dimensional micro / nano structure precursor with a metal-organic framework coating is calcined at 300–500 °C in an inert gas atmosphere to obtain a self-standing transition metal armor catalyst.
[0044] The catalyst has the advantages of readily available raw materials, mild conditions, and good reproducibility, and has good prospects for industrial application.
[0045] The morphology of the self-supporting active components of the three-dimensional micro-nano structures includes nanowires, nanoflowers, nano-sea urchins, nano-corals, and nanoleaves. In addition to the various three-dimensional micro-nano structures mentioned above, other morphological structures that can increase the specific surface area of the active components can also be adopted, such as spheres with regular pore sizes, which have high porosity and large specific surface area.
[0046] The morphology of the self-standing active component of the three-dimensional micro-nano structure can be controllably prepared by means of nitrate raw material using a hydrothermal method or an electrodeposition method. The nitrate raw material of the self-standing active component of the three-dimensional micro-nano structure is at least one of nickel nitrate, cobalt nitrate, and iron nitrate.
[0047] The steps for preparing three-dimensional micro / nano structures using the hydrothermal method are as follows:
[0048] Nitrate, urea, and ammonium fluoride are used as raw materials;
[0049] Nitrate, urea, and ammonium fluoride are mixed in a predetermined stoichiometric ratio to form a mixed solution;
[0050] The mixed solution and the substrate material are placed together in a high-pressure reactor, and the active components are grown in situ on the substrate material through hydrothermal reaction.
[0051] The steps for preparing three-dimensional micro / nano active components by the electrodeposition method are as follows:
[0052] Nitrate solution was used as the raw material;
[0053] A three-electrode system was constructed by using the substrate material as the working electrode and platinum electrode and Hg / HgO electrode as the counter electrode and reference electrode.
[0054] Active components are formed by electrodeposition on the surface of the substrate material.
[0055] In one embodiment, to further enhance the stability of the catalyst, the outer inert material protective layer further includes a gradient protective layer, wherein the gradient protective layer is provided sequentially from the inside out with:
[0056] The highly conductive inner layer, composed of graphene or graphite carbon, is about five nanometers thick and has a high degree of lattice matching with the active components.
[0057] The insulating intermediate layer is composed of ultrathin boron nitride or titanium carbide, with a thickness of about two to three nanometers. This layer has high chemical stability.
[0058] The selectively permeable outer layer is composed of microporous silica and has selective permeation capabilities.
[0059] The highly conductive inner layer ensures rapid electron transport, the insulating middle layer isolates the active components from the harsh reaction environment, the selectively permeable outer layer permeates and screens reactant molecules to improve catalytic selectivity, and the synergistic effect of each layer can significantly improve the durability of the catalyst under complex operating conditions.
[0060] The method for generating the gradient protection layer is as follows:
[0061] The substrate on which the self-standing three-dimensional micro / nano structure active components have been grown was cleaned with ethanol and deionized water and then vacuum dried.
[0062] The substrate was placed in an atomic layer deposition (ALD) reaction chamber and heated to 400°C. Acetylene was used as the carbon source, and argon was used as the carrier gas and purge gas. One deposition cycle consisted of 0.1 s pulsed acetylene followed by 10 s purging argon. The above cycle was repeated 50 times to form a dense, highly conductive graphitized carbon layer with a thickness of about 5 mm on the active components of the substrate.
[0063] The reaction chamber temperature was maintained at 400℃, and boron trichloride and ammonia were used as precursors. A deposition cycle was set as follows: pulse boron trichloride 0.05s - purging argon gas 10s - pulse ammonia gas 0.1s - purging argon gas 15s, and the cycle was repeated 20 times to form an ultrathin, continuous, chemically inert hexagonal boron nitride layer with a thickness of about 2-3nm on the inner carbon layer.
[0064] The reaction chamber temperature was reduced to 150℃; silane and ozone were used as precursors; a deposition cycle was set as follows: 0.1s pulse silane - 10s argon purging - 0.2s pulse ozone - 15s argon purging, and the cycle was repeated 10 times to form a silica layer with a microporous structure and a thickness of about 1-2nm. By controlling the number of cycles and the ozone pulse time, the micropore size can be adjusted to achieve the molecular sieving function.
[0065] After deposition, the catalyst was cooled to room temperature under an argon atmosphere and then removed to obtain a self-standing armored catalyst with a core-shell composite structure.
[0066] In one embodiment, nanocapsules containing gallium-indium alloy are embedded in the outer inert material protective layer. When microcracks appear in the outer inert material protective layer due to mechanical stress or localized corrosion, and these microcracks initiate and propagate within the protective layer, the high stress field at the crack tip causes the microcapsules along the path to rupture. Upon rupture, the liquid gallium-indium alloy, driven by capillary forces, rapidly flows out of the capsules and immediately into the narrow crack gap. Due to its low viscosity (approximately twice that of water) and low surface tension, it can spread rapidly and anchor itself to the inner wall of the crack, creating a fresh surface with high surface energy. Liquid gallium-indium alloy (especially gallium) has good wettability to many solid surfaces (such as carbon, metal oxides, and nitrides). It spontaneously spreads along the inner wall of the crack, forming a thin liquid film that covers the exposed fresh interface. Gallium atoms in the liquid gallium undergo weak physical adsorption or coordination with defects or functional groups on the carbon surface, facilitating adhesion.
[0067] The situation is even more favorable if the crack is deep enough to expose the active transition metal components inside. Gallium metal is reducing and undergoes a slight reduction-alloying reaction with the oxide surface, forming a very thin intermetallic compound at the interface. This is equivalent to creating a "chemical rivet" between the liquid metal and the crack wall, achieving strong mechanical anchoring and electrical connection.
[0068] When liquid metal is exposed to an electrolyte, the gallium on the surface of the liquid GaIn alloy reacts with oxygen or water, spontaneously and rapidly forming a dense, amorphous gallium oxide (Ga2O3) film only 1-3 nanometers thick. This film is highly stable, continuous, and insulating. This solid oxide film is dense and chemically inert, effectively preventing corrosive media from penetrating along cracks and protecting the internal active components.
[0069] These nanocapsules endow the catalyst with active defense and self-repair capabilities, significantly extending the catalyst's lifespan under dynamic reaction conditions and reducing the frequency and cost of catalyst replacement.
[0070] The embedding steps of gallium-indium alloy nanocapsules are as follows:
[0071] Nanocapsules with a particle size of approximately 100-200 nm were prepared using an in-situ polymerization method, with liquid gallium-indium alloy (Ga75In25) as the core material and urea-formaldehyde resin as the wall material. The nanocapsules were then filtered, washed, and dried for later use.
[0072] The microcapsules were uniformly dispersed in a precursor solution for preparing the protective layer, i.e., dimethylimidazole dissolved in an aqueous methanol solution;
[0073] By using spray-assisted chemical vapor deposition or dip-coating, a precursor solution containing microcapsules is uniformly coated or deposited on the surface of a self-standing active component. Subsequently, it is treated at high temperature in an inert atmosphere to carbonize or densify the protective layer precursor, forming a robust matrix in which the microcapsules are completely encapsulated.
[0074] In one embodiment, an interface layer composed of a monolayer silane coupling agent or phosphorus- or sulfur-containing organic ligands is disposed between the structural matrix and the outer inert material protective layer. One end of the interface layer forms a strong chemical bond (MO-Si, MS, MP) with the metal active component, and the other end forms a covalent bond (CC, BNC) with the carbon or boron nitride protective layer, thereby achieving a strong and tough chemical bond from the core to the shell. The strong chemical bond fundamentally solves the interface delamination problem caused by the difference in thermal expansion coefficients of the core and shell materials, and improves the mechanical and thermal stability of the overall structure.
[0075] The steps for preparing the interface layer are as follows:
[0076] The substrate with the grown self-standing active components was treated in an ozone UV cleaner for 15 minutes to enrich its surface with hydroxyl groups (-OH).
[0077] The substrate was immersed in an anhydrous toluene solution (2% by volume) containing 3-aminopropyltriethoxysilane (APTES) and refluxed at 80°C for 6 hours. The ethoxy groups of APTES undergo hydrolytic condensation with the hydroxyl groups on the surface of the active component to form strong Si-OM covalent bonds, while amino groups (-NH2) are grafted onto the surface.
[0078] After the reaction was completed, the substrate was thoroughly washed with toluene and ethanol to remove the physically adsorbed coupling agent, and then vacuum dried.
[0079] The modified substrate was placed in a tube furnace and heated to 600°C in an Ar / H2 (5%) atmosphere. Ethylene (C2H4) was introduced as a carbon source. Under high temperature and the action of catalysts (Ni / Co, etc.), ethylene cracked and deposited on the surface to form a carbon layer. The amino groups (-NH2) grafted on the surface can serve as additional carbon and nitrogen sources at high temperature, reacting with the deposited carbon to form a CNC or CN covalent bond network, thereby forming a strong covalent bond interface between the carbon protective layer and the silane layer.
[0080] Cooling to room temperature under an Ar atmosphere yields a core-shell composite catalyst with strong interfacial bonding.
[0081] The outer inert material protective layer is applied to the structural substrate in an in-situ assembled manner.
[0082] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.
Claims
1. A self-standing transition metal armored catalyst, characterized in that, A core-shell composite structure is formed by using a self-standing active component with a three-dimensional micro-nano structure as the structural matrix and covering it with an inert material protective layer. The self-standing active component with the three-dimensional micro-nano structure includes metal oxides, metal phosphides, metal sulfides and metal selenides, and the outer inert material protective layer includes a carbon layer and boron nitride.
2. The self-standing transition metal armored catalyst according to claim 1, characterized in that, The morphology of the self-supporting active components in the three-dimensional micro / nano structure includes nanowires, nanoflowers, nanosea urchins, nanocorals, and nanoleaves.
3. The self-standing transition metal armored catalyst according to claim 1, characterized in that, The morphology of the self-standing active component of the three-dimensional micro-nano structure can be controllably prepared by means of nitrate raw material using a hydrothermal method or an electrodeposition method. The nitrate raw material of the self-standing active component of the three-dimensional micro-nano structure is at least one of nickel nitrate, cobalt nitrate, and iron nitrate.
4. The self-standing transition metal armored catalyst according to claim 3, characterized in that, The steps for preparing three-dimensional micro / nano structures using the hydrothermal method are as follows: Nitrate, urea, and ammonium fluoride are used as raw materials; Nitrate, urea, and ammonium fluoride are mixed in a predetermined stoichiometric ratio to form a mixed solution; The mixed solution and the substrate material are placed together in a high-pressure reactor, and the active components are grown in situ on the substrate material through hydrothermal reaction.
5. The self-standing transition metal armored catalyst according to claim 3, characterized in that, The steps for preparing three-dimensional micro / nano active components by the electrodeposition method are as follows: Nitrate solution was used as the raw material; A three-electrode system was constructed by using the substrate material as the working electrode and platinum electrode and Hg / HgO electrode as the counter electrode and reference electrode. Active components are formed by electrodeposition on the surface of the substrate material.
6. The self-standing transition metal armored catalyst according to claim 1, characterized in that, The outer inert material protective layer further includes a gradient protective layer, which is provided sequentially from the inside out with the following components: The highly conductive inner layer is composed of graphene or graphite carbon. The insulating intermediate layer is composed of ultrathin boron nitride or titanium carbide; The outer layer is selectively permeated and consists of microporous silica.
7. The self-standing transition metal armored catalyst according to claim 1, characterized in that, The outer inert material protective layer contains embedded gallium-indium alloy nanocapsules.
8. The self-standing transition metal armored catalyst according to claim 1, characterized in that, An interface layer composed of a monolayer silane coupling agent or a phosphorus- or sulfur-containing organic ligand is provided between the structural matrix and the outer inert material protective layer.
9. The self-standing transition metal armored catalyst according to claim 1, characterized in that, The outer inert material protective layer is applied to the structural substrate in an in-situ assembled manner.
10. A method for preparing a self-standing transition metal armored catalyst, characterized in that the step... include: Take the corresponding weights of nitrate, urea and ammonium fluoride according to the set stoichiometric ratio, and dissolve the nitrate, urea and ammonium fluoride in ultrasonic water by magnetic stirring to form a mixed solution; The mixed solution and the substrate were transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 120–180 °C. The substrate that had undergone hydrothermal reaction was washed alternately with ethanol and ultrapure water, and then vacuum dried to obtain a self-standing three-dimensional micro / nano structure precursor. An appropriate amount of dimethylimidazole was dissolved in an aqueous methanol solution. The self-standing three-dimensional micro / nano structure precursor was then immersed in the dimethylimidazole and methanol solution for coordination self-assembly. After standing for several hours, a metal-organic framework coating layer was formed on the surface of the self-standing three-dimensional micro / nano structure precursor. A self-standing three-dimensional micro / nano structure precursor with a metal-organic framework coating is calcined at 300–500 °C in an inert gas atmosphere to obtain a self-standing transition metal armor catalyst.