Two-dimensional ferroelectric single-atom ag loaded electrocatalyst

Abstract

The application discloses a novel two-dimensional ferroelectric single-atom Ag loaded electrocatalyst Ag@CIPS. By loading transition group metal Ag on the surface of two-dimensional ferroelectric material CuInP2S6 which can maintain ferroelectric polarization at room temperature, a single-atom catalyst Ag@CIPS is prepared, and the catalytic activity of the single-atom catalyst can be regulated by the polarization of the substrate. Due to the regulation of the spontaneous polarization of the ferroelectric substrate on the outer electron structure of the Ag atom, the Ag atom which originally does not have catalytic activity shows good HER activity under the regulation of the substrate. After the single-layer CIPS surface is loaded with Ag, the overpotential of the catalytic HER process is greatly reduced. With the increase of the substrate layer, the polarization intensity of the substrate is enhanced, and excellent HER performance is shown. Moreover, after the single-atom Ag particle is used to modify the CIPS material, the overpotential and Tafel slope of the electrocatalytic hydrogen evolution reaction are reduced, and the catalytic activity is improved.

Description

Technical Field

[0001] This invention relates to the fields of ferroelectricity and electrocatalysis, and particularly to the field of electrocatalytic hydrogen evolution materials. Background Technology

[0002] Energy and the environment are two crucial issues in the development of modern society and economy. Currently, the mainstay of human society's energy economy remains non-renewable traditional fossil fuels such as coal, oil, and natural gas. With technological advancements and social development, energy supply issues are becoming increasingly prominent, and the environmental problems caused by the large amounts of greenhouse gases produced by the combustion of fossil fuels with high carbon content are becoming increasingly serious. To improve the ecological environment and protect our shared home, countries around the world are striving to find new, environmentally friendly clean energy sources to replace traditional fossil fuels. Hydrogen is a clean, renewable, non-carbon-based energy carrier with high specific energy density and is harmless to the environment (its final energy release product is water), making it a promising new energy source. If large-scale clean production of hydrogen is achieved, it can not only alleviate the current heavy reliance on traditional fossil fuels, but a fuel structure with a high hydrogen content can also reduce the environmental impact of carbon emissions.

[0003] Currently, commercial hydrogen production methods mainly include water electrolysis, fossil fuel reforming, and industrial byproduct purification. However, the latter two methods still rely heavily on traditional energy consumption, resulting in the generation of large amounts of greenhouse gases, which contradicts the goal and original intention of "low-carbon and environmentally friendly" production. In contrast, water electrolysis can utilize surplus electricity generated from clean energy sources such as wind and solar power to produce hydrogen, achieving "zero carbon emissions" throughout the entire process.

[0004] Hydrogen production through water electrolysis utilizes electricity converted from renewable energy sources such as solar and wind power to generate hydrogen. The produced hydrogen is then stored and transported using hydrogen storage technology, thus achieving a decentralized reaction between electrical and chemical energy. However, water electrolysis currently accounts for only 5% of global hydrogen production, primarily due to its low conversion efficiency and high energy consumption. The reason water electrolysis requires a large external energy supply is mainly because the two half-reactions in the process, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), have significant kinetic barriers. Theoretically, the thermodynamic reaction barrier for water electrolysis is 1.23V, but commercially available electrolyzers typically operate at voltages of 1.8–2.0V. Therefore, developing effective catalysts to reduce the overpotential in water electrolysis, thereby reducing reaction energy consumption, is a current research hotspot. Currently, Pt-based materials and Ru / Ir oxides are recognized as excellent catalysts for the HER and OER reactions, but they are scarce and expensive, and only function in the half-reactions of water electrolysis, making large-scale commercial application difficult. Therefore, the search for non-precious metal-based or low-precious metal-content water electrolysis catalysts with lower overpotentials is a continuous research direction. In particular, the ability to use the catalyst simultaneously in both half-reactions of water electrolysis can optimize the structure and manufacturing cost of the water electrolysis device, thereby further improving the catalyst utilization rate. Summary of the Invention

[0005] Based on the aforementioned problems of existing technologies, this invention aims to provide a low-cost catalyst with high electrocatalytic efficiency. Based on theoretical analysis and the establishment of material models, it seeks a novel catalyst that satisfies both low cost and high electrocatalytic efficiency. Based on the established material models, it uses material preparation technology to realize the catalyst and apply it to electrocatalysis.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution.

[0007] This invention provides a two-dimensional ferroelectric electrocatalyst supported on single-atom Ag. A single-atom catalyst (Ag / CIPS) with catalytic activity modulated by substrate polarization is prepared by loading a single-atom transition metal Ag onto the surface of a two-dimensional ferroelectric material CuInP2S6, which maintains ferroelectric polarization at room temperature. Due to the regulation of the outer electron structure of Ag atoms by the spontaneous polarization of the ferroelectric substrate, Ag atoms that originally lacked catalytic activity exhibit good HER activity under the substrate's regulation.

[0008] CuInP2S6 is a room-temperature ferroelectric semiconductor with a bandgap of 2.2 eV. Its ferroelectricity originates from the structural distortion of Cu and In ions within the sulfur octahedron. Below the Curie temperature of CuInP2S6, Cu ions are asymmetrically distributed near off-center Cu1 sites, resulting in spontaneous polarization. By applying a voltage, the polarization sequence of CuInP2S6 can switch between the AFE and FE states. When an external electric field larger than its coercive field is applied to CuInP2S6, taking a downward electric field as an example, the external electric field causes Cu and In ions in the material to shift, forming an electric dipole moment, which macroscopically manifests as downward polarization. In an independent CuInP2S6 monolayer, the AFE state is the ground state, and the free energy of the FE state is approximately 48 meV higher than that of the AFE state. Although the AFE state is the ground state of an independent CIPS monolayer, its interaction with the electrode can alter the energy difference between the ferroelectric and antiferroelectric states, resulting in different ground states. Furthermore, CIPS is a typical vdW FE material, and its switchable room-temperature out-of-plane polarization has been experimentally verified in bulk materials and nanosheets.

[0009] However, CIPS, a monolayer ferroelectric phase, is a direct bandgap semiconductor. Its valence band is contributed by Cu atoms and their surrounding S atoms, while its conduction band is contributed by In atoms and their surrounding S atoms. However, its conductivity is relatively weak. Therefore, CIPS itself does not possess electrocatalytic properties, nor does it possess hydrogen evolution catalytic properties. This is why CIPS has received little attention in the field of electrocatalysis.

[0010] Ag has valence electrons of d10s1, with its d orbitals in a stable, fully filled state. Ferropolarization is primarily regulated in the s orbitals. Individual electrons are free and do not interact with the filled d subshells. Because such interactions (which occur in previous transition metals) reduce electron migration, Ag exhibits extremely high electrical conductivity, the strongest among all metals. However, in the field of electrocatalysis, pure Ag has failed to demonstrate considerable catalytic activity.

[0011] This invention loads single Ag atoms onto CIPS (Cyclic Inductively Coupled Particulate Air). The single Ag atoms are in a de-electron state on different surfaces, and the charge transfer of Ag atoms is greater in Ag / down-CIPS. The main charge transfers with the Ag atoms are the three adjacent S atoms and In atoms. The spontaneously polarized ferroelectric phase of CIPS effectively regulates the electronic structure of the loaded Ag atoms. The Gibbs free energy (ΔG) of Ag atoms in the polarization-up direction of monolayer CIPS is shown in the figure. H* The value is -0.239 eV. After the substrate polarization is reversed, the ΔG in the polarization-down direction is... H*With a value of -0.091 eV, extremely close to that of commercially available noble metal electrocatalysts Pt (-0.09 eV), it exhibits excellent catalytic activity. Furthermore, it displays different Gibbs free energy values ​​(ΔG) in the two directions. H* The level provides the possibility of regulating the opening and closing of the HER reaction.

[0012] This invention uses CIPS, which has a very weak hydrogen evolution catalytic ability, and Ag, which does not have the ability to catalyze hydrogen evolution, to design a single-atom catalyst. In the computational structural model, the unit cell of the two-dimensional structure of the substrate is first optimized during the design process. In order to remove the interaction between the periodicity of the layered structure, a vacuum layer of more than 20 Å is introduced in the out-of-plane polarization direction, which allows the lattice of the two-dimensional material to relax in the x and y directions and the free relaxation of all atoms.

[0013] Single-layer CIPS constructed in the XY plane 2 Two supercells adsorb Ag single atoms; wherein the initial distance between the Ag single atoms and the monolayer CIPS is set between 3-3.5 Å, and the length of the vacuum layer applied in the Z direction (perpendicular to the thin layer direction) is greater than 20 Å. When the monolayer CIPS is in the ferroelectric state, Ag single atoms are easily adsorbed at the center positions of the three S atoms, resulting in a total of 41 single-atom catalyst atoms; while in the bilayer CIPS, the ferroelectric polarization is further increased, the band gap is reduced, and the electrostatic potential of different polarization surfaces is further expanded (>0.8 eV), resulting in a total of 81 single-atom catalyst atoms. Furthermore, the thickness of the monolayer CIPS is between 3.3-3.5 Å, and the interlayer spacing of the bilayer CIPS is between 3.1-3.2 Å.

[0014] In the constructed Ag@CuInP2S6, CIPS has a hexagonal crystal structure, which is a van der Waals layered structure. The lattice constant of CIPS is 6.12 Å, and each unit cell contains one copper atom, one indium atom, two phosphorus atoms, and six sulfur atoms. CIPS has an octahedral framework of sulfur, with PP atom pairs, and Cu and In atoms filling the interstices of the octahedrons. Single-atom Ag is loaded on the two-dimensional CuInP2S6 surface.

[0015] For the upward-polarized upper surface of CuInP2S6, the chemical potential of isolated Ag atoms is lower than the conduction band minimum (CBM) and higher than the valence band maximum (VBM) of the monolayer ferroelectric phase CuInP2S6, resulting in relatively little charge transfer between them. When the polarization direction changes to downward, both the CBM and VBM of the monolayer ferroelectric phase CuInP2S6 decrease in energy. At this point, the CBM of CuInP2S6 is lower than the chemical potential of Ag, and Ag transfers more negative charge to the monolayer ferroelectric phase CuInP2S6. Therefore, the charge transfer controlled by the polarization direction plays a crucial role in the charge density of the loaded single atoms.

[0016] In the construction of the two-dimensional ferroelectric supported single-atom Ag electrocatalyst model of this invention, the entire hydrogen evolution reaction (HER) is a classic two-electron transfer reaction, consisting of three states (original, unoriginal, and unoriginal). Intermediate transition products and final products The reaction is described using a step diagram, and its reaction formula is:

[0017]

[0018]

[0019] From a physicochemical perspective, * represents the active site on the catalyst. The adsorption Gibbs free energy on the catalyst surface ( This can effectively assess the reaction mechanism and adsorption / desorption capacity. The calculation method is as follows:

[0020]

[0021] in, The zero-point energy difference is the energy between the adsorbed state H* and the gaseous state H2, where T is the temperature, set to 298K. This is an entropy change. The energy difference between the hydrogen adsorption state and the original state is shown below:

[0022] .

[0023] The formulas for calculating entropy and zero-point energy are as follows:

[0024]

[0025] Where, h, ν, These are Planck's constant, the vibrational frequency, and Boltzmann's constant, respectively.

[0026] Based on the above theoretical analysis and material model establishment, the inventors of this invention, through specific material preparation techniques, have achieved the preparation of a single-atom catalyst (Ag@CuInP2S6) with catalytic activity modulated by substrate polarization by loading single Ag atoms onto the surface of a two-dimensional ferroelectric material CuInP2S6, which can maintain ferroelectric polarization at room temperature. The microstructure of the single-atom catalyst Ag@CuInP2S6 is as follows: CuInP2S6 has a van der Waals layered structure, i.e., a thin layer, with Ag atoms uniformly and dispersed in single-atom form on the thin-layered CuInP2S6 surface; preferably, the Ag loading is less than 4% wt. When the Ag loading exceeds 4% wt, there is aggregation and coating phenomenon among the Ag atoms loaded on the CuInP2S6 surface.

[0027] When the single-atom catalyst Ag@CuInP2S6 described above is applied to HER, the spontaneous polarization direction of the ferroelectric CIPS substrate is controlled by an external electric field, thereby controlling the Gibbs free energy of Ag atoms and thus the on / off state of the HER reaction. For example, the Gibbs free energy (ΔG) of a single Ag atom in the polarization-up direction of a monolayer CIPS is... H* The value is -0.239 eV; when the substrate CIPS polarization is reversed, the ΔG in the CIPS polarization-down direction is... H* The different Gibbs ΔG values ​​exhibited by Ag single atoms in two directions, at -0.091 eV. H* The horizontal plane makes it possible to control the opening and closing of the HER reaction of the catalyst by adjusting the spontaneous polarization direction of the ferroelectric material CIPS through an external electric field.

[0028] The method for preparing the above-mentioned single-atom catalyst Ag@CuInP2S6 according to the present invention includes the following steps:

[0029] 1) Place elemental Cu powder, In particles, P powder and S powder in a vacuum quartz tube, keep warm for a sufficient time, and then take out CuInP2S6 powder; use a cell disruptor to break the interlayer van der Waals forces, so that the layers are separated.

[0030] 2) To prepare an AgNO3 solution, add ammonia dropwise until a clear mixed solution is obtained.

[0031] 3) Place the CuInP2S6 obtained in step 1) into the mixed solution obtained in step 2), keep it warm for a certain period of time, and then take it out; the warming temperature is 70-90℃ and the warming time is 20-28h.

[0032] 4) Wash the product with deionized water and ethanol, and then dry it to obtain the final product.

[0033] The technical effects of this invention are as follows:

[0034] This invention first designs a model of a single-atom Ag catalyst supported on a two-dimensional ferroelectric phase CuInP2S6 using theoretical modeling, and verifies its electronic structure and catalytic performance, which are tunable with ferroelectric polarization. Specifically, when Ag single atoms are supported on the downward polarized surface of a monolayer CIPS, With a value of -0.091 eV, it is comparable to the known excellent noble metal catalyst Pt. (for -0.09 eV); as the ferroelectric polarization of the substrate increases, The HER performance is closer to 0, at -0.027 eV, surpassing that of traditional noble metal catalysts. When the ferroelectric polarization direction of the substrate is reversed, the HER performance decreases, demonstrating effective regulation of the HER activity of single-atom catalysts by ferroelectric polarization. This invention enriches the application scope of two-dimensional ferroelectric materials in the energy field and provides new ideas for the modification of single-atom catalysts.

[0035] Furthermore, based on the theoretical model, this invention utilizes material preparation techniques to prepare a single-atom Ag electrocatalyst on a two-dimensional ferroelectric phase CuInP2S6. Ag atoms are loaded onto the surface of CuInP2S6, a two-dimensional ferroelectric material that can maintain ferroelectric polarization at room temperature, to obtain a single-atom Ag@CnInP2S6 electrocatalyst. Electrocatalytic hydrogen evolution performance tests of Ag@CnInP2S6 confirmed that Ag, which previously lacked catalytic activity, exhibits excellent electrocatalytic hydrogen evolution activity under the regulation of the CuInP2S6 substrate.

[0036] Two-dimensional ferroelectric CnInP2S6 materials are rarely used in the field of electrocatalytic hydrogen evolution due to their weak conductivity. This invention enriches the application scope of two-dimensional ferroelectric materials in electrocatalytic hydrogen evolution and provides a new approach for the modification of single-atom catalysts. Attached Figure Description

[0037] Figure 1 This is a structural diagram of the optimized monolayer CuInP2S6 material in Example 1.

[0038] Figure 2 This is a structural diagram of the bilayer CuInP2S6 material obtained in Example 1.

[0039] Figure 3 The diagram shows the structure of the bilayer CuInP2S6 loaded with single-atom Ag in polarization-up (Ag / up-BL-CIPS) and polarization-down (Ag / down-BL-CIPS) configurations described in Example 1.

[0040] Figure 4 The diagram shows the HER Gibbs free energy changes of the bilayer CuInP2S6 loaded with single-atom Ag in polarization-up (Ag / up-BL-CIPS) and polarization-down (Ag / down-BL-CIPS) configurations described in Example 1.

[0041] Figure 5 This is a SEM image of the CuInP2S6 material prepared in Example 2.

[0042] Figure 6 This is a SEM image of the Ag@CnInP2S6 material prepared in Example 2.

[0043] Figure 7 The images show the SEM and EDS images of the Ag@CnInP2S6 material prepared in Example 2.

[0044] Figure 8 This is a comparison of the linear sweep voltammetric curves of the Ag@CuInP2S6 material prepared in Example 2 and the unloaded Ag CuInP2S6 material.

[0045] Figure 9 This is a comparison of the electrocatalytic Tafel slopes of the Ag@CuInP2S6 material prepared in Example 2 and the unloaded Ag CuInP2S6 material. Detailed Implementation

[0046] The inventors constructed a two-dimensional ferroelectric electrocatalyst supported on single-atom Ag atoms using computational and simulation methods. By supporting single-atom Ag atoms on the surface of CuInP2S6, a two-dimensional ferroelectric material that maintains ferroelectric polarization at room temperature, a single-atom catalyst (Ag@CuInP2S6) with catalytic activity modulated by substrate polarization was obtained. Furthermore, the inventors used specific material preparation techniques to fabricate the simulated catalyst and verified its excellent catalytic performance through testing. This invention utilizes the spontaneous polarization of the ferroelectric substrate to regulate the outer electron structure of Ag atoms, enabling Ag atoms that originally lacked catalytic activity to exhibit good HER activity under the substrate's regulation. The activity of this catalyst was further verified experimentally.

[0047] Example 1: Model Building and Performance Simulation Prediction

[0048] First, the inventors built a model and predicted the performance of the novel two-dimensional ferroelectric supported single-atom Ag electrocatalyst to be prepared. The model building steps are as follows.

[0049] (1) Single-layer CuInP2S6 was selected as the substrate material for constructing the novel two-dimensional ferroelectric supported single-atom Ag electrocatalyst. The substrate material was optimized to obtain: the lattice constant of CuInP2S6 is 6.12 Å. When the (001) direction of CuInP2S6 was cut, the thickness of the single-layer CIPS monolayer was obtained to be 3.3-3.5 Å. CuInP2S6 has a hexagonal crystal structure, which is a van der Waals layered structure. Each unit cell contains one copper atom, one indium atom, two phosphorus atoms, and six sulfur atoms. It has an octahedral framework with S atoms, PP atom pairs, and Cu and In atoms filling the octahedral voids. Figure 1 The diagram shows the structure of the optimized monolayer CuInP2S6 material.

[0050] (2) The monolayer CuInP2S6 obtained in step 1) is expanded to 2x2 and subjected to rotational stacking tests to obtain a bilayer CuInP2S6 structure that is closest to the actual experimental conditions and has a stable structure, such as Figure 2 The diagram shows the structure of the obtained bilayer CuInP2S6 material. The interlayer spacing of the bilayer CIPS is 3.1–3.2 Å.

[0051] (3) A monolayer of CuInP2S6 was constructed in the XY plane. 2. Supercell, adsorbing Ag atoms; wherein the initial distance between the Ag and the monolayer CuInP2S6 is set between 3-3.5 Å, and the length of the vacuum layer applied in the Z direction (perpendicular to the thin layer direction) is greater than 20 Å; when the monolayer CuInP2S6 is in the ferroelectric state, the single-atom catalyst obtained by adsorbing Ag totals 41 atoms; while in the ferroelectric state, the ferroelectric polarization of the bilayer CuInP2S6 further increases, the band gap decreases, and the single-atom catalyst obtained by adsorbing Ag at different positions on the CuInP2S6 surface totals 81 atoms, as shown below. Figure 3 The diagram shows the structure of bilayer CuInP2S6 with polarization-up (Ag / up-BL-CIPS) and polarization-down (Ag / down-BL-CIPS) single-atom Ag loading. This embodiment uses... Figure 3 The model was used to calculate the HER catalytic activity step diagram. Figure 4 The HER Gibbs free energy variation plots calculated for the model structures of bilayer CuInP2S6 with polarization-up (Ag / up-BL-CIPS) and polarization-down (Ag / down-BL-CIPS) loaded with single-atom Ag atoms.

[0052] The non-centrosymmetric structure of the CuInP2S6 substrate leads to a deviation of the positive and negative charge centers, resulting in differences in electrostatic potential between the different surfaces. When the chemical potential of the metal single atom is in a suitable position, the degree of charge transfer between the two surfaces will change significantly (e.g., Ag), thereby altering the charge density and orbital spin splitting degree of the metal atoms, affecting the adsorption effect of H atoms, and thus changing the catalytic activity of HER. The difference in HER catalytic performance between oppositely polarized surfaces widens, such as... Figure 4 As shown, in the polarization-down direction of bilayer CuInP2S6, the theoretical overpotential of Ag / down-BL-CIPS is -0.027V, which is better than most noble metals including Pt, demonstrating excellent HER performance.

[0053] Example 2: Preparation and testing of two-dimensional ferroelectric supported single-atom Ag electrocatalyst Ag@CuInP2S6

[0054] The experimental preparation steps of the two-dimensional ferroelectric supported single-atom Ag electrocatalyst Ag@CuInP2S6 are as follows.

[0055] 1) Preparation of CuInP2S6 powder: Place elemental Cu powder, In particles, P powder and S powder in a vacuum quartz tube, keep it at a sufficient temperature for a sufficient time, and then take it out to obtain CuInP2S6 powder.

[0056] 2) Use a cell disruptor to break the van der Waals forces between CuInP2S6 powder layers, causing the layers to separate and obtain a thin layer of CuInP2S6.

[0057] 3) Prepare AgNO3 solutions of different concentrations and 10% ammonia solution. Add the 10% ammonia solution dropwise to the 16 mmol / L, 10 mmol / L, and 5 mmol / L AgNO3 solutions, respectively, until no further precipitate forms in the mixture. Place the thin-layer CuInP2S6 from step 2) into the mixture and maintain the temperature at 70-90℃ for 20-28 hours. Wash the powder three times with deionized water and ethanol, and dry at 60℃ for 8 hours to obtain Ag@CuInP2S6 with different Ag loadings, i.e., the two-dimensional ferroelectric supported single-atom Ag electrocatalyst.

[0058] Various tests were performed on the two-dimensional ferroelectric supported single-atom Ag electrocatalyst Ag@CuInP2S6 prepared in Example 2, as follows.

[0059] (1) SEM testing: The thin-layer CuInP2S6 prepared in Example 2 and the finally prepared two-dimensional ferroelectric supported single-atom Ag electrocatalyst Ag@CuInP2S6 were observed under low-magnification and high-magnification SEM scanning electron microscopes. Figure 5The image shows a scanning electron microscope (SEM) image of the thin CuInP2S6 material obtained in step 2) of Example 2. It can be clearly seen from the image that CuInP2S6 is in the form of a two-dimensional thin layer, i.e., a van der Waals layered structure. Figure 6 The image shows a scanning electron microscope (SEM) image of Ag@CuInP2S6 prepared using the method described in Example 2. As can be observed from the image, individual Ag atoms are distributed in a scattered manner on the surface of the CuInP2S6 sheet, achieving the effect of loading single-atom Ag particles onto two-dimensional ferroelectric CIPS.

[0060] (2) EDS test: Energy dispersive spectroscopy (EDS) analysis was performed on the two-dimensional ferroelectric supported single-atom Ag electrocatalyst Ag@CuInP2S6 prepared in Example 2, such as... Figure 7 As shown in the figure, the Ag element is uniformly distributed, which further illustrates that the uniform loading of Ag single atoms in Ag@CuInP2S6 on the surface of the ferroelectric material CuInP2S6 increases the number of electrocatalytic active sites and achieves the effect of improving the electrocatalytic activity of the material.

[0061] (3) Linear sweep voltammetry test: The Ag@CuInP2S6 material prepared in Example 2 was used to make a membrane electrode and assembled into a three-electrode system for linear sweep voltammetry test. The linear sweep voltammetry curves of Ag@CuInP2S6 electrocatalysts with different Ag loadings prepared in Example 2 were obtained. Figure 8 Linear sweep voltammetry curves of Ag@CuInP2S6 prepared in Example 2 and CuInP2S6 without Ag loading are shown in the figure. A clear trend in catalytic activity can be observed: when the single-atom Ag loading is in the range of 1% wt to 3% wt, the overpotential (η) of the Ag@CuInP2S6 material is... 10 The value decreases with decreasing Ag loading, but is generally lower than the value of CuInP2S6 material itself. 10 This phenomenon may occur for two reasons: first, at this loading range, Ag atoms exist in isolation, increasing the number of catalytically active sites on the surface of CuInP2S6; second, based on computational models, the two-dimensional ferroelectric material CuInP2S6, which maintains ferroelectric polarization at room temperature, has a regulatory effect on Ag atoms, giving Ag@CuInP2S6 an extremely close ΔG value. H* When the Ag loading reaches 4% wt, the η10 value exceeds that of unloaded Ag CuInP2S6, exhibiting a "poisoning" phenomenon. This may be because after the loading exceeds the threshold, Ag atoms may aggregate and coat the surface of CuInP2S6 material, reducing the exposure of catalytic active sites and weakening the polarization regulation effect, which manifests as an increase in overpotential. Specific overpotential data are shown in Table 1 below.

[0062] Table 1. Overpotentials of hydrogen evolution catalyzed by CuInP2S6 with different Ag loadings in Example 1

[0063] Ag load 0%wt 1%wt 2%wt 3%wt 4%wt overpotential 0.630V 0.434V 0.540V 0.574V 0.727V

[0064] (4) Figure 9 This is a comparison of the Tafel slopes of the electrocatalytic Tafel material prepared in Example 2 and the unloaded CuInP2S6 material. In the electrocatalytic hydrogen evolution study, a lower Tafel slope indicates higher catalytic activity. Figure 9 As can be seen, when the Ag loading is in the range of 1% wt and 2% wt, the Tafel slope increases with increasing loading, and the catalytic activity of the material decreases, but overall it is still lower than that of the unloaded CuInP2S6 material. This proves that an appropriate amount of Ag atomic loading improves the electrocatalytic hydrogen evolution activity of CuInP2S6 material. This may be because an appropriate amount of Ag loading increases the catalytic activity of individual catalytic active sites on the surface of CuInP2S6 material, accelerating the exchange and transfer of atoms, thus exhibiting a lower Tafel slope.

[0065] The above description is merely a partial embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A two-dimensional ferroelectric monatomic electrocatalyst model, characterized in that: The monatomic atom is a transition metal Ag monatomic atom; the two-dimensional ferroelectric is a single-layer CIPS and a double-layer CIPS, wherein the thickness of the single-layer CIPS is between 3.3-3.5 Å; the double-layer CIPS is obtained by rotating and stacking two layers of 2x2 supercells of the single-layer CIPS, and the interlayer spacing of the double-layer CIPS is between 3.1-3.2 Å; The single-layer CIPS constructs a 2x2 supercell in an XY plane and adsorbs the Ag monatomic atom; in the monatomic atom electrocatalyst model, the single-layer CIPS is in a ferroelectric state, and a total of 41 atoms are obtained by adsorbing the Ag monatomic atom on the surface; and the double-layer CIPS is in a ferroelectric state, the ferroelectric polarization is increased, the band gap is reduced, and a total of 81 atoms are obtained by adsorbing the Ag monatomic atom. The CIPS refers to CuInP2S6, has a hexagonal crystal structure, is a Van der Waals layered structure, the lattice constant of the CIPS is 6.12 Å, one crystal cell has one copper atom, one indium atom, two phosphorus atoms and six sulfur atoms; the CIPS has an octahedral framework of S, a P-P atom pair, and Cu and In atoms filled in the octahedral voids.

2. The two-dimensional ferroelectric monatomic catalyst model of claim 1, wherein: The initial distance between the Ag monatomic atom and the single-layer CIPS is set to be between 3-3.5 Å, and the length of the vacuum layer in the Z direction, that is, perpendicular to the thin layer direction, is more than 20 Å.

3. The method of constructing a two-dimensional ferroelectric monolayer atomic electrocatalyst model according to any one of claims 1-2, wherein, The method comprises the following steps: 1) selecting a single-layer CIPS and a double-layer CIPS as substrate materials for constructing the two-dimensional ferroelectric loaded monatomic atom electrocatalyst model; 2) obtaining the lattice constant of the CIPS and performing calculation after optimization; 3) obtaining the single-layer CIPS and the double-layer CIPS; 4) performing 2x2 supercell expansion on the single-layer CIPS in step 3) and adsorbing an Ag monatomic atom on the layer surface, adsorbing an Ag monatomic atom on the double-layer CIPS in step 3), and forming the two-dimensional ferroelectric loaded monatomic atom electrocatalyst model; 5) measuring and calculating the structure performance parameters of the two-dimensional ferroelectric loaded monatomic atom electrocatalyst model.

4. The method of claim 3, wherein the two-dimensional ferroelectric monatomic catalyst model is constructed by: The lattice constant of the CIPS in step 2) is 6.12 Å. ​ 5. The method for constructing a two-dimensional ferroelectric supported single-atom electrocatalyst model according to claim 3, characterized in that, In step 3), the single-layer CIPS is obtained by cutting a section in the (001) direction of the CIPS to obtain a single-layer structure CIPS; two layers of 2x2 supercells of the obtained single-layer CIPS are expanded and stacked to obtain a double-layer CIPS; the thickness of the single-layer CIPS is 3.3-3.5 Å; and the interlayer spacing of the double-layer CIPS is between 3.1-3.2 Å.

6. The method for constructing a two-dimensional ferroelectric supported single-atom electrocatalyst model according to claim 3, characterized in that, In step 4), the single-layer CIPS constructs a 2x2 supercell in an XY plane and adsorbs an Ag monatomic atom; the initial distance between the Ag monatomic atom and the single-layer CIPS is set to be between 3-3.5 Å, and the length of the vacuum layer in the Z direction, that is, perpendicular to the CIPS thin layer direction, is more than 20 Å; the single-layer CIPS is in a ferroelectric state, and a total of 41 atoms are obtained by adsorbing the Ag monatomic atom; and the double-layer CIPS is in a ferroelectric state, the ferroelectric polarization is increased, the band gap is reduced, and a total of 81 atoms are obtained by adsorbing the Ag monatomic atom.

7. A two-dimensional ferroelectric monatomic electrocatalyst, characterized in that: The electrocatalyst takes two-dimensional ferroelectric material CIPS as a substrate, the two-dimensional ferroelectric material CIPS has a ferroelectric phase with spontaneous polarization; the chemical formula of the two-dimensional ferroelectric material CIPS is CuInP2S6, the micro-morphology of CIPS presents a van der Waals layered structure, i.e. a thin layered structure; transition metal Ag is uniformly and dispersedly distributed in the form of single atom on the surface of the thin layered CIPS; and the loading amount of Ag single atom in the electrocatalyst is less than 3%wt.

8. The use of a two-dimensional ferroelectric monatomic catalyst according to claim 7 in the HER, characterized in that: When the electrocatalyst is applied to HER, the spontaneous polarization direction of the ferroelectric material CIPS substrate is regulated by an external electric field, thereby regulating the Gibbs free energy of Ag atom, and realizing the regulation of the opening and closing of the HER reaction.

9. A method of making a two-dimensional ferroelectric single-atom supported electrocatalyst of claim 7, wherein, The method comprises the following steps: 1) Put elemental Cu powder, In particles, P powder and S powder into a vacuum quartz tube, and perform heat preservation treatment to obtain CuInP2S6 powder; 2) Use a cell disrupter to destroy the interlayer van der Waals force of the CuInP2S6 powder, so as to separate the layers from each other, thereby obtaining thin layered CuInP2S6; 3) Prepare an AgNO3 solution, and add ammonia water dropwise into the solution until the mixed solution is clear; 4) Put the thin layered CuInP2S6 obtained in step 2) into the mixed solution of step 3), and take out the product after heat preservation for a certain time; 5) Wash the product with deionized water and ethanol, and dry the product, thereby obtaining the two-dimensional ferroelectric single atom loaded electrocatalyst.

10. The method for preparing a two-dimensional ferroelectric supported single-atom electrocatalyst according to claim 9, characterized in that: The concentration of the AgNO3 solution is determined according to the loading amount of Ag in the two-dimensional ferroelectric single atom loaded electrocatalyst, and the loading amount of Ag in the two-dimensional ferroelectric single atom loaded electrocatalyst is less than 3wt%.

11. The method for preparing a two-dimensional ferroelectric supported single-atom electrocatalyst according to claim 9, characterized in that: In step 4), the heat preservation temperature is 70-90℃, and the heat preservation time is 20-28h.

Images