Monatomic catalyst, its preparation method and application
By preparing single-atom catalysts through pyrolysis-impregnation and using attapulgite and alkali lignin to prepare precursor carbon materials, the problems of easy agglomeration and dependence on precious metals of single-atom catalysts were solved, and efficient and low-cost hydrogen production through water electrolysis was achieved.
Patent Information
- Application Number
- CN202610573261.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-28
- Publication Date
- 2026-06-26
AI Technical Summary
Existing preparation methods are difficult to effectively avoid the aggregation and deactivation of single-atom catalysts, and precious metal catalysts lead to high costs for hydrogen production by water electrolysis.
Single-atom catalysts were prepared by a two-step pyrolysis-impregnation method. Precursor carbon materials were prepared using attapulgite and alkali lignin. Metal ions were introduced by combining the impregnation method, which restricted the migration of metal ions, prevented agglomeration, and maximized the utilization of metal atoms and high-density active sites.
This achieves efficient utilization of metal atoms and uniform distribution of active sites, reducing the cost of hydrogen production through water electrolysis and improving catalytic efficiency and stability.
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Figure CN122279651A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, and in particular to a single-atom catalyst, its preparation method, and its application. Background Technology
[0002] Hydrogen production through water electrolysis has attracted much attention due to its environmental friendliness; however, the slow kinetics of its half-reaction hydrogen evolution reaction (HER) limit the efficiency of electrochemical water splitting, and its high dependence on precious metal catalysts (such as Pt / C) leads to high costs. Therefore, the development of inexpensive and high-performance non-precious metal catalysts has become a research hotspot.
[0003] Single-atom catalysts have shown great potential in the field of catalysis due to their extremely high atomic utilization and unique electronic structure. However, existing preparation methods (such as co-precipitation and impregnation-calcination methods) often face problems such as metal atom aggregation, uneven distribution of active sites, and deactivation. Summary of the Invention
[0004] Based on this, the purpose of this invention is to provide a single-atom catalyst, its preparation method, and its application. The single-atom catalyst is prepared by a two-step pyrolysis-impregnation method, which eliminates the need for secondary sintering after impregnation. This solves the problem that single-atom catalysts have potential but are prone to agglomeration and deactivation. It also solves the problem that the HER reaction is slow and the reliance on noble metal catalysts leads to high costs.
[0005] First aspect:
[0006] A method for preparing a single-atom catalyst includes the following steps: Alkali lignin, attapulgite and carbonate are mixed and then placed in an inert atmosphere and heated to 500-700℃ at a heating rate of 1-10℃ / min and held for 1-3h to obtain precursor carbon material. The precursor carbon material is immersed in a metal ion solution for 1-3 hours, filtered and dried to obtain the single-atom catalyst. The metal ion solution contains at least one of nickel ions, cobalt ions, manganese ions, and copper ions, and anions include at least one of sulfate ions, nitrate ions, and acetate ions.
[0007] The preparation method of this invention uses attapulgite and alkali lignin to prepare precursor carbon materials, and then introduces metal ions through an impregnation method. Simultaneously, the defects present in the precursor carbon materials effectively restrict the migration of metal ions and prevent aggregation. Ultimately, the metal ions are firmly anchored on the carbon support in single-atom form, maximizing the utilization of metal atoms and providing a high density of HER active sites.
[0008] When preparing precursor carbon materials, if the heating rate is too slow, the preparation time will be too long; if the heating rate is too fast, it will not be conducive to the full carbonization of the material. Multiple synergistic effects can be achieved at a pyrolysis temperature of 500~700℃. This temperature range can not only ensure the full carbonization of alkali lignin and effectively remove free water from the material, but also avoid destroying the layered chain structure of attapulgite. At the same time, this temperature is sufficient to decompose carbonates, allowing them to act as activators, promote the formation of porous structures, and increase the specific surface area.
[0009] After pyrolysis, the layered chain structure of attapulgite is not destroyed, and metal ions can be fixed in the structure through cation exchange. The carbonization of alkali lignin can provide some defects to fix metal ions.
[0010] As a preferred embodiment, the carbonate includes at least one of sodium carbonate and potassium carbonate; the mass ratio of alkali lignin, attapulgite, and carbonate is 1~2:1~2:1. Excessive attapulgite content can mask defect sites and reduce the ability to fix single atoms; excessive alkali lignin content can lead to excessive nickel atom fixation, forming atomic clusters, and the structure is prone to collapse; simultaneously, excessive carbonate content will cause metal ions to tend towards basic metal carbonates rather than metal single atoms; insufficient carbonate content will affect the pore-forming ability, thus affecting the amount of single-atom fixation.
[0011] As a preferred embodiment, the mass ratio of alkali lignin to attapulgite is 1:1. Within this range, the synergistic effect of alkali lignin and attapulgite can be optimally balanced, maintaining the integrity of the structure, giving the catalyst a certain strength to prevent collapse, and also fixing a certain amount of single atoms to prevent the formation of atomic clusters.
[0012] As a preferred embodiment, the solid-liquid ratio of the precursor carbon material to the metal ion solution is no greater than 1 g / L. With a fixed total amount of metal ions, a too-low solid-liquid ratio can easily lead to localized overloading and agglomeration of the metal ions; appropriately increasing the solid-liquid ratio helps to uniformly disperse nickel ions and stably prepare single-atom catalysts.
[0013] As a preferred embodiment, the concentration of metal ions in the metal ion solution is no greater than 200 ppm. If the metal ion concentration is too high, the ion exchange rate will be too fast, and aggregation may easily occur.
[0014] As a preferred embodiment, the process further includes the following step: the precursor carbon material needs to be ground before being placed in the metal ion solution, to a mesh size of no more than 400 mesh. Generally, for catalysts, the finer the particle size, the higher the catalytic efficiency; however, if the mesh size is too high, the sieving time will also increase significantly, affecting the preparation efficiency.
[0015] As a preferred embodiment, the method further includes the following step: immersing the precursor carbon material in a metal ion solution and placing it in a shaking incubator at 100-200 rpm at 25°C for impregnation. The shaking reaction in the incubator results in a more uniform impregnation process and a faster impregnation speed.
[0016] The second aspect: A single-atom catalyst prepared by the method described in the first aspect has a metal element loading of 3-5 wt% of the single-atom catalyst mass. When the loading is too low, the catalytic efficiency is low; when the loading is too high, agglomeration is likely to occur.
[0017] Third aspect: The application of the single-atom catalyst described in the second aspect in the electrolysis of water. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the preparation process of a single-atom catalyst.
[0019] Figure 2 These are the SEM images and elemental analysis diagrams of the single-atom catalyst prepared in Example 1.
[0020] Figure 3 This is a schematic diagram of the single-atom dispersion characteristics of the single-atom catalyst prepared in Example 1.
[0021] Figure 4 This is the XRD pattern of the single-atom catalyst prepared in Example 1.
[0022] Figure 5 These are the LSV curves of the single-atom catalysts prepared in Examples 1-4.
[0023] Figure 6 This is the stability curve of the single-atom catalyst prepared in Example 1. Detailed Implementation
[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0028] like Figure 1 As shown, a method for preparing a single-atom catalyst includes the following steps: Alkali lignin, attapulgite, and carbonate are mixed in a mass ratio of 1~2:1~2:1, preferably 2:2:1.
[0029] After mixing, the mixture is placed in an inert atmosphere and heated to 500-700℃ at a heating rate of 1-10℃ / min. The temperature is maintained for 1-3 hours, and the mixture is naturally cooled to room temperature before being removed to obtain the precursor carbon material.
[0030] The precursor carbon material is ground to a mesh size not exceeding 400 mesh and then immersed in a metal ion solution, with the solid-liquid ratio of the precursor carbon material to the metal ion solution not exceeding 1 g / L. The mixture is then immersed in a shaking incubator at 25°C and 100–200 rpm for 1–3 hours. After filtration, the filter residue is dried to obtain a single-atom catalyst.
[0031] The carbonates include sodium carbonate and potassium carbonate, with potassium carbonate being the preferred choice. Because potassium salts are present in attapulgite, potassium carbonate is the most preferred carbonate to avoid introducing excessive amounts of other elements, although there is no significant difference in its effectiveness.
[0032] In the metal ion solution, the metal ion includes at least one selected from nickel ion, cobalt ion, manganese ion, and copper ion, and the concentration is not greater than 200 ppm; the anion includes at least one selected from sulfate ion, nitrate ion, and acetate ion. Preferably, the metal ion is nickel ion, the anion is nitrate ion, and the metal ion solution can be a nickel nitrate solution.
[0033] A single-atom catalyst with a metal element loading of 3-5 wt% of the single-atom catalyst mass. It can be used for catalytic water electrolysis.
[0034] Example 1 This embodiment provides a nickel single-atom catalyst, prepared by the following steps: Alkali lignin, attapulgite, and potassium carbonate were mixed in a mass ratio of 2:2:1; then placed in a ceramic boat and transferred to a tube furnace. Argon gas was introduced through a sealed pipe, and the tube furnace was purged for 30 minutes. Subsequently, the temperature was increased to 600°C at a heating rate of 10°C / min, held for 1 hour, and then naturally cooled to room temperature before being removed to obtain the precursor carbon material.
[0035] The precursor carbon material was ground to 400 mesh and then added to a nickel nitrate solution with a solid-liquid ratio of 1 g / L and a nickel ion content of 100 ppm. The mixture was then immersed in a shaking incubator at 200 rpm for 2 hours at 25°C. After filtration, the filter residue was dried for 12 hours to obtain a nickel single-atom catalyst (ATP / AL-Ni).
[0036] like Figure 2 As shown, the surface of the ATP / AL-Ni material exhibits a porous and particle-packed structure composed of nanoscale particles, with pores between the particles facilitating electrolyte permeation or gas diffusion. Furthermore, elemental analysis reveals that Ni is uniformly distributed across the material surface.
[0037] like Figure 3 As shown, under a large-angle annular dark-field scanning electron microscope with spherical aberration correction, prominent bright spots that contrast sharply with the surrounding dark environment can be observed. These bright spots are nickel single atoms.
[0038] like Figure 4 As shown, the peak at 2θ = 20.68° is attributed to the diffraction peak of SiO2 (PDF#43-0596), while the peaks at 28.69° and 34.35° correspond to KAlSiO4 (PDF#48-1028). No peak shape belonging to nickel or its related compounds was found, which is consistent with the characteristics of nickel single atoms.
[0039] like Figure 5 As shown, ATP / AL-Ni was placed in a 1 mol / L KOH solution. When the current density was 10 mA cm⁻¹... -2 At that time, the overpotential was 161mV, and when the current density was 100mA / cm², -2 At that time, the overpotential was 271 mV. Among several different metal single-atom catalysts, the nickel single-atom catalyst showed the best HER performance.
[0040] like Figure 6 As shown, ATP / AL-Ni can be applied at 100 mA cm⁻¹ -2 The catalyst has been running stably for 100 hours without significant activity degradation, indicating that this single-atom catalyst has good stability and promising application prospects.
[0041] Example 2 This embodiment provides a manganese single-atom catalyst, prepared by the following steps: Alkali lignin, attapulgite, and potassium carbonate were mixed in a mass ratio of 2:2:1; then placed in a ceramic boat and transferred to a tube furnace. Argon gas was introduced through a sealed pipe, and the tube furnace was purged for 30 minutes. Subsequently, the mixture was heated to 650°C at a heating rate of 8°C / min, held at that temperature for 2 hours, and then naturally cooled to room temperature before being removed to obtain the precursor carbon material.
[0042] The precursor carbon material was ground to 400 mesh and then added to a manganese nitrate solution with a solid-liquid ratio of 1 g / L and a manganese ion content of 100 ppm. The mixture was then immersed in a shaking incubator at 200 rpm for 2 hours at 25°C. After filtration, the filter residue was dried for 12 hours to obtain a manganese single-atom catalyst (ATP / AL-Mn).
[0043] like Figure 5 As shown, ATP / AL-Mn was placed in a 1 mol / L KOH solution, and when the current density was 10 mA cm⁻¹ -2 At that time, the overpotential was 163mV, and when the current density was 100mA cm⁻¹ -2 At that time, the overpotential was 276mV.
[0044] Example 3 This embodiment provides a cobalt single-atom catalyst, prepared by the following steps: Alkali lignin, attapulgite, and potassium carbonate were mixed in a mass ratio of 2:2:1; then placed in a ceramic boat and transferred to a tube furnace. Argon gas was introduced through a sealed pipe, and the tube furnace was purged for 30 minutes. Subsequently, the mixture was heated to 700°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then naturally cooled to room temperature before being removed to obtain the precursor carbon material.
[0045] The precursor carbon material was ground to 400 mesh and then added to a cobalt nitrate solution with a solid-liquid ratio of 1 g / L and a cobalt ion content of 100 ppm. The mixture was then immersed in a shaking incubator at 200 rpm for 2 hours at 25°C. After filtration, the filter residue was dried for 12 hours to obtain a cobalt single-atom catalyst (ATP / AL-Co).
[0046] like Figure 5 As shown, ATP / AL-Co was placed in a 1 mol / L KOH solution. When the current density was 10 mA cm⁻¹... -2 At that time, the overpotential was 168mV, and when the current density was 100mA cm⁻¹ -2 At that time, the overpotential was 286mV.
[0047] Example 4 This embodiment provides a copper single-atom catalyst, prepared by the following steps: Alkali lignin, attapulgite, and potassium carbonate were mixed in a mass ratio of 2:2:1; then placed in a ceramic boat and transferred to a tube furnace. Argon gas was introduced through a sealed pipe, and the tube furnace was purged for 30 minutes. Subsequently, the mixture was heated to 500°C at a heating rate of 1°C / min, held at that temperature for 3 hours, and then naturally cooled to room temperature before being removed to obtain the precursor carbon material.
[0048] The precursor carbon material was ground to 400 mesh and then added to a copper nitrate solution with a solid-liquid ratio of 1 g / L and a copper ion content of 100 ppm. The mixture was then immersed in a shaking incubator at 200 rpm for 2 hours at 25°C. After filtration, the filter residue was dried for 12 hours to obtain a copper single-atom catalyst (ATP / AL-Cu).
[0049] like Figure 5 As shown, ATP / AL-Cu was placed in a 1 mol / L KOH solution. When the current density was 10 mA cm⁻¹... -2 At that time, the overpotential was 173mV, and when the current density was 100mA / cm², -2 At that time, the overpotential was 315mV.
[0050] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. For those skilled in the art, any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments without departing from the concept of the present invention are all within the protection scope of the present invention.
Claims
1. A method for preparing a single-atom catalyst, characterized in that, Includes the following steps: Alkali lignin, attapulgite and carbonate are mixed and then placed in an inert atmosphere and heated to 500-700℃ at a heating rate of 1-10℃ / min and held for 1-3h to obtain precursor carbon material. The precursor carbon material is immersed in a metal ion solution for 1-3 hours, filtered and dried to obtain the single-atom catalyst. The metal ion solution contains at least one of nickel ions, cobalt ions, manganese ions, and copper ions, and anions include at least one of sulfate ions, nitrate ions, and acetate ions.
2. The method for preparing the single-atom catalyst according to claim 1, characterized in that, The carbonate includes at least one of sodium carbonate and potassium carbonate; the mass ratio of the alkali lignin, attapulgite and carbonate is 1~2:1~2:
1.
3. The method for preparing the single-atom catalyst according to claim 2, characterized in that, The mass ratio of the alkali lignin to attapulgite is 1:
1.
4. The method for preparing the single-atom catalyst according to claim 1, characterized in that, The solid-liquid ratio of the precursor carbon material to the metal ion solution is no greater than 1 g / L.
5. The method for preparing the single-atom catalyst according to claim 4, characterized in that, The concentration of metal ions in the metal ion solution is no greater than 200 ppm.
6. The method for preparing the single-atom catalyst according to claim 1, characterized in that, The process includes the following steps: Before placing the precursor carbon material in the metal ion solution, it needs to be ground to a mesh size of no more than 400 mesh.
7. The method for preparing the single-atom catalyst according to claim 1, characterized in that, The method also includes the following steps: immersing the precursor carbon material in a metal ion solution and placing it in a shaking table at 100-200 rpm at 25°C.
8. A single-atom catalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The metal element loading is 3-5 wt% of the mass of the single-atom catalyst.
9. The application of the single-atom catalyst of claim 8 in water electrolysis.