Bimetallic-based two-dimensional nanocatalytic material, preparation method and application thereof

Abstract

The application discloses a supported bimetallic-based two-dimensional nanometer catalytic material and a preparation method and application thereof, and relates to the technical field of catalysts. The preparation method comprises the following steps: preparing a monolayer structure or a few-layer structure of a plasmonic nanosheet; dispersing the plasmonic nanosheet in a solvent and adding a copper source to prepare a first mixed solution; stirring the first mixed solution in an inert gas environment, and then performing freeze-drying treatment and calcination treatment in a hydrogen atmosphere to prepare a nanosheet-Cu; adding HAuCl4 and HCl into the nanosheet-Cu in sequence, mixing, and then reacting under preset light irradiation conditions to prepare a supported bimetallic-based two-dimensional nanometer catalytic material nanosheet-Cu-Au. The application can realize the functional division and spatial cooperation of bimetallic active sites, promote the efficient generation, separation and directional transmission of photo-generated carriers, and thus improve the reaction efficiency and product selectivity of the co-reduction of nitrate and carbon dioxide to urea.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to supported bimetallic two-dimensional nanocatalytic materials, their preparation methods, and applications. Background Technology

[0002] Urea, as an important basic chemical raw material and nitrogen fertilizer, has wide applications in agricultural production and fine chemical industries. In recent years, the direct synthesis of urea through the co-reduction of nitrate and carbon dioxide followed by a CN coupling reaction has been considered a promising green synthesis route to replace the traditional Haber-Bosch and Bosch-Meiser tandem processes. Especially in photocatalytic or photoelectrocatalytic systems, utilizing solar energy to drive this reaction process can not only reduce energy consumption and carbon emissions but also achieve the synergistic resource utilization of nitrate pollutants and greenhouse gases, thus attracting widespread attention.

[0003] However, existing catalytic material systems for this reaction still have significant shortcomings. First, the multi-electron and multi-proton coupling reaction and the key CN coupling step place high demands on the distribution of active sites and the matching of reaction kinetics in the catalyst. Existing catalysts often struggle to simultaneously handle both nitrate reduction and carbon dioxide activation processes, leading to an incoordination between intermediate formation and conversion pathways, thus limiting the efficiency and selectivity of urea production. Second, while existing high-entropy alloys, single-atom catalysts, or multi-component composite catalysts have improved catalytic performance to some extent, their preparation processes are complex, energy-intensive, and expensive, and they struggle to achieve precise control over the spatial distribution of active components. Furthermore, some systems rely on external bias voltage to drive the reaction, further increasing energy consumption and hindering green and sustainable development.

[0004] Furthermore, although a few studies have attempted to construct dual-active-site or multi-component synergistic catalytic systems, the following key issues remain in practical applications: First, the lack of clear functional division and spatial proximity among different active components leads to long migration paths for reaction intermediates and low CN coupling efficiency; second, the insufficient matching between the generation, separation, and transport processes of photogenerated carriers and surface reaction kinetics easily triggers side reactions and reduces the selectivity of the target product; third, the regulatory mechanism of illumination conditions (such as wavelength, intensity, and time) on the formation of active components and interface structure is still unclear, making it difficult to achieve controllable construction of highly efficient catalytic structures. Summary of the Invention

[0005] One objective of the first aspect of this invention is to provide a method for preparing a bimetallic-based two-dimensional nanocatalytic material, which solves the technical problems in the prior art of unclear division of active sites of catalyst, poor matching between photogenerated carrier behavior and reaction kinetics in the process of urea preparation by co-reduction of nitrate and carbon dioxide, and the resulting low urea yield and selectivity.

[0006] Another objective of the first aspect of this invention is to further improve the overall photocatalytic or electrocatalytic performance.

[0007] A second aspect of the present invention is to provide a supported bimetallic two-dimensional nanocatalytic material prepared according to the above preparation method.

[0008] The third aspect of this invention aims to provide the application of the above-mentioned supported bimetallic two-dimensional nanocatalytic material in urea synthesis.

[0009] According to a first aspect of the present invention, the present invention provides a method for preparing a bimetallic-based two-dimensional nanocatalytic material, comprising the following steps:

[0010] Plasma nanoantennas are prepared and then stripped to obtain plasma nanosheets with a single-layer or few-layer structure.

[0011] The plasma nanosheets were dispersed in a solvent, and a copper source was added to prepare a first mixed solution.

[0012] The first mixed solution was stirred in an inert gas environment, and then freeze-dried and calcined in a hydrogen atmosphere to prepare nanosheet-Cu.

[0013] The nanosheet-Cu was dissolved in the solvent, and the precursors HAuCl4 and HCl were added sequentially. After mixing, the mixture was reacted under preset light conditions to reduce and grow Au particles in the nanosheet-Cu. After centrifugation and washing, the supported bimetallic two-dimensional nanocatalytic material nanosheet-Cu-Au was prepared.

[0014] The molar ratio of copper ions in the copper source to the metal element M in the plasma nanoantenna is any value between 0.1% and 20%, and the light intensity under the preset illumination condition is 80 mW / cm². 2 -120mW / cm 2 Any value in the range, with the illumination time being any value between 5 min and 30 min.

[0015] Optionally, the plasma nanoantenna is a Ti3C2T. x Any one of Nb2C or WSe2.

[0016] Optionally, the copper source is any one of copper acetate, copper nitrate, or copper sulfate.

[0017] Optionally, the stirring speed is any value between 150 rpm and 250 rpm, and the stirring time is any value between 3 h and 4.5 h.

[0018] Optionally, the calcination temperature of the hydrogen atmosphere calcination treatment is any value between 250℃ and 350℃, and the calcination time is any value between 2.5h and 3.5h, so that the particle size of the Cu particles in the nanosheet-Cu is any value between 4nm and 6nm.

[0019] Optionally, the plasma nanoantenna is the Ti3C2T x The fabrication of the plasma nanoantenna includes the following steps:

[0020] Ti3AlC2 powder was added to hydrofluoric acid solution for etching to remove the Al layer. After centrifugation and washing until neutral, the etched product was obtained.

[0021] Add an aqueous solution of tetramethylammonium hydroxide to the etching product and sonicate to achieve peeling and dispersion. After standing, centrifuge to remove excess tetramethylammonium hydroxide.

[0022] The supernatant was collected by centrifugation to obtain a few-layer Ti3C2T. x The nanosheet dispersion is subjected to the freeze-drying process described above to obtain the plasma nanosheets.

[0023] Optionally, the concentration of the hydrofluoric acid solution is any value between 40wt% and 50wt%.

[0024] Optionally, the concentration of HAuCl4 is any value between 5mM and 15mM, and the concentration of HCl is any value between 6M and 12M.

[0025] According to a second aspect of the present invention, the present invention also provides a supported bimetallic-based two-dimensional nanocatalyst material prepared according to the preparation method of the supported bimetallic-based two-dimensional nanocatalyst material according to any one of the above claims.

[0026] According to a third aspect of the present invention, the present invention also provides the application of the above-described supported bimetallic two-dimensional nanocatalytic material in urea synthesis.

[0027] This invention constructs a two-dimensional nanoantenna with plasma-responsive capability and obtains single-layer or few-layer nanosheets through exfoliation to improve the specific surface area and the exposure of active sites. Subsequently, by controlling the molar ratio of copper ions to metal element M in the nanoantenna to be 0.1%-20%, uniform loading of the copper component on the nanosheet surface is achieved under inert and reducing atmospheres, forming stable nitrogen species activation sites. Furthermore, in a system containing chloroauric acid and hydrochloric acid, at 80 mW / cm²... 2 -120mW / cm 2Photodeposition was performed under conditions of high light intensity and 5-30 min illumination time, enabling Au particles to be reduced and grown in situ on the nanosheet-Cu surface, thereby achieving interfacial coupling and synergistic distribution of Au and Cu components. Based on the above structural construction and parameter control, this application can form bimetallic active centers with clear functional division and spatial proximity on a two-dimensional nanosheet carrier. In this center, the Cu component preferentially participates in the nitrate reduction process, while the Au particles preferentially promote carbon dioxide activation. The synergistic distribution of the two at the nanoscale effectively shortens the migration path of reaction intermediates and lowers the energy barrier of the CN coupling process. At the same time, the controlled illumination conditions introduced during photodeposition further regulate the deposition rate of Au particles and their ratio with Cu particles, matching the generation, separation, and transport processes of photogenerated carriers with the reaction kinetics of the bimetallic active sites, thereby suppressing side reactions and improving the selectivity of target product formation.

[0028] Furthermore, the calcination temperature of the hydrogen atmosphere calcination treatment in this invention is any value between 250℃ and 350℃, and the calcination time is any value between 2.5h and 3.5h, so that the particle size of Cu particles in the nanosheet-Cu is any value between 4nm and 6nm. By synergistically controlling the calcination temperature and time, the matching optimization between Cu particle size and plasma hot carrier extraction efficiency is achieved, thereby providing a high-efficiency electron transport and reaction basis for subsequent Au deposition and Au-Cu interface synergistic catalysis, and further improving the overall photocatalytic performance or electrocatalytic performance.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0030] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0031] Figure 1 This is a schematic flowchart of a method for preparing a supported bimetallic two-dimensional nanocatalytic material according to an embodiment of the present invention;

[0032] Figure 2 This is a bar chart showing the Au / Ti molar ratio of a bimetallic-based two-dimensional nanocatalyst material under different illumination times according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic distribution diagram of Au particle deposition sites under different single-light wavelength irradiation of a bimetallic-based two-dimensional nanocatalytic material according to an embodiment of the present invention.

[0034] Figure 4 This is a schematic curve of carrier extraction by Cu particles of different sizes in a supported bimetallic two-dimensional nanocatalytic material according to an embodiment of the present invention.

[0035] Figure 5 This is a schematic flowchart of a method for preparing plasma nanosheets according to an embodiment of the present invention;

[0036] Figure 6 This is an AFM morphology characterization image of plasma nanosheets according to one embodiment of the present invention;

[0037] Figure 7 This is a cross-sectional view of the surface height of a plasma nanosheet according to an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram illustrating the principle of urea synthesis under pure sunlight catalysis using a bimetallic-based two-dimensional nanocatalytic material supported according to an embodiment of the present invention.

[0039] Figure 9 This is a high-resolution transmission electron microscope image of the bimetallic-based two-dimensional nanocatalytic material supported according to Example 1 of the present invention;

[0040] Figure 10 This is an energy dispersive X-ray spectral elemental distribution diagram of the bimetallic-based two-dimensional nanocatalytic material supported according to Embodiment 1 of the present invention;

[0041] Figure 11 These are the X-ray diffraction patterns of the bimetallic-based two-dimensional nanocatalysts supported in Example 1 and Comparative Example 3 of the present invention.

[0042] Figure 12 This is an electronic state characterization diagram of Ti in MXene-Cu-Au according to Embodiment 1 of the present invention;

[0043] Figure 13 This is an electronic state characterization diagram of Cu in MXene-Cu-Au according to Embodiment 1 of the present invention;

[0044] Figure 14 This is a high-resolution transmission electron microscope image of the bimetallic-based two-dimensional nanocatalytic material supported according to Example 2 of the present invention;

[0045] Figure 15 The transient fluorescence spectra of the supported bimetallic two-dimensional nanocatalytic materials according to Example 1 and Comparative Example 1 of the present invention are shown.

[0046] Figure 16 This is the transient fluorescence spectrum of the bimetallic-based two-dimensional nanocatalytic material supported according to Comparative Example 2 of the present invention;

[0047] Figure 17 This is the transient fluorescence spectrum of the bimetallic-based two-dimensional nanocatalytic material supported according to Comparative Example 3 of the present invention;

[0048] Figure 18 These are the Raman spectra of the bimetallic-based two-dimensional nanocatalysts supported in Example 1 and Comparative Example 3 of the present invention;

[0049] Figure 19 This is a comparison diagram of photocurrent density in photoelectrocatalytic urea synthesis using bimetallic-based two-dimensional nanocatalytic materials supported in Example 1, Comparative Example 1, and Comparative Example 3 of the present invention.

[0050] Figure 20 This is a comparison diagram of photocurrent density in photoelectrocatalytic urea synthesis using bimetallic-based two-dimensional nanocatalytic materials supported in Examples 1, 4, and 5 of the present invention.

[0051] Figure 21 This is a comparison diagram of photocurrent density in photoelectrocatalytic urea synthesis using bimetallic-based two-dimensional nanocatalytic materials supported in Examples 1, 6, and 7 of the present invention.

[0052] Figure 22 This is a comparison diagram of photocurrent density in photoelectrocatalytic urea synthesis using bimetallic-based two-dimensional nanocatalytic materials supported in Examples 1, 8, and 9 of the present invention.

[0053] Figure 23 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the bimetallic-based two-dimensional nanocatalytic material supported according to Example 1 of the present invention;

[0054] Figure 24 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalyst materials according to Example 1, Comparative Example 4 and Comparative Example 5 of the present invention.

[0055] Figure 25 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalytic materials according to Example 1, Comparative Example 6 and Comparative Example 7 of the present invention.

[0056] Figure 26 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalyst materials according to Example 1, Comparative Example 8 and Comparative Example 9 of the present invention.

[0057] Figure 27 This is a graph showing the photoelectrocatalytic stability of the supported bimetallic two-dimensional nanocatalytic material according to Example 1 of the present invention under light and dark conditions.

[0058] Figure 28 These are pulse curves of the supported bimetallic two-dimensional nanocatalyst materials in the nitrate reaction system according to Comparative Examples 1 and 2 of the present invention.

[0059] Figure 29 The pulse curves of the supported bimetallic two-dimensional nanocatalyst materials in the bicarbonate reaction system according to Comparative Examples 1 and 2 of the present invention are shown.

[0060] Figure 30 The graphs show pulsed chemisorption-conversion measurements of the supported bimetallic two-dimensional nanocatalyst material in the nitrate reaction system under light and dark conditions, as described in Comparative Example 1 of the present invention.

[0061] Figure 31 The graphs show pulsed chemisorption-conversion measurements of the supported bimetallic two-dimensional nanocatalyst material in the bicarbonate reaction system under light and dark conditions, respectively, according to Comparative Example 2 of the present invention.

[0062] Figure 32 This is a urea yield-time curve of the bimetallic-based two-dimensional nanocatalytic material used in urea synthesis according to Example 1 of the present invention. Detailed Implementation

[0063] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0064] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0065] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0066] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0067] Figure 1 This is a schematic flowchart of a method for preparing a supported bimetallic two-dimensional nanocatalytic material according to an embodiment of the present invention. Figure 2 This is a bar chart showing the Au / Ti molar ratio of a bimetallic-based two-dimensional nanocatalyst material supported by an embodiment of the present invention under different illumination times. Figure 3 This is a schematic distribution diagram of Au particle deposition sites under different single-light wavelength irradiation of a bimetallic-based two-dimensional nanocatalyst material according to an embodiment of the present invention. Figure 4 This is a schematic curve illustrating carrier extraction by Cu particles of different sizes in a supported bimetallic two-dimensional nanocatalytic material according to an embodiment of the present invention.

[0068] like Figure 1 As shown, the present invention provides a method for preparing a bimetallic-based two-dimensional nanocatalytic material, comprising the following steps:

[0069] Step S100: Prepare a plasma nanoantenna and peel it off to obtain a plasma nanosheet with a single-layer or few-layer structure.

[0070] Step S200: Disperse plasma nanosheets in a solvent and add a copper source to prepare a first mixed solution;

[0071] Step S300: The first mixed solution is stirred in an inert gas environment, and then freeze-dried and calcined in a hydrogen atmosphere to obtain nanosheet-Cu.

[0072] Step S400: Dissolve the nanosheet-Cu in a solvent, add the precursor HAuCl4 and HCl sequentially, mix, and react under a preset light irradiation condition to reduce and grow Au particles in the nanosheet-Cu. After centrifugation and washing, prepare the supported bimetallic two-dimensional nanocatalyst nanosheet-Cu-Au. The molar ratio of copper ions in the copper source to metal element M in the plasma nanoantenna is any value between 0.1% and 20%, and the light intensity under the preset light irradiation condition is 80 mW / cm². 2 -120mW / cm 2The illumination time is any value between 5 min and 30 min. Here, the molar ratio of copper ions in the copper source to metal element M in the plasma nanoantenna can be 0.1%, 0.5%, 1.0%, 5.0%, 10.0%, 15.0%, or 20%, or any other value between 0.1% and 20%. The light intensity under the preset illumination conditions can be 80 mW / cm². 2 90mW / cm 2 100mW / cm 2 110mW / cm 2 Or 120mW / cm 2 It can also be 80mW / cm 2 -120mW / cm 2 Any other value in the range, the illumination time can be 5 min, 10 min, 20 min or 30 min, or any other value between 5 min and 30 min.

[0073] This embodiment provides a method for preparing a bimetallic-based two-dimensional nanocatalytic material, comprising the following steps: First, a plasma nanoantenna is prepared and then exfoliated to obtain plasma nanosheets with a single-layer or few-layer structure. The plasma nanosheets are dispersed in a solvent, and a copper source is added to prepare a first mixed solution. The first mixed solution is stirred in an inert gas environment and then subjected to freeze-drying and calcination in a hydrogen atmosphere to obtain nanosheet-Cu. Subsequently, the nanosheet-Cu is dispersed in a solvent, and the precursors chloroauric acid and hydrochloric acid are added sequentially. After mixing, the mixture is transferred to a transparent container and reacted under preset illumination conditions to reduce Au particles in situ and grow them on the surface of the nanosheet-Cu. After centrifugation and washing, the bimetallic-based two-dimensional nanocatalytic material nanosheet-Cu-Au is obtained.

[0074] In this embodiment, a two-dimensional nanoantenna with plasma-responsive capability is constructed, and single-layer or few-layer nanosheets are obtained through exfoliation to improve the specific surface area and the exposure of active sites. Subsequently, by controlling the molar ratio of copper ions to metal element M in the nanoantenna to be 0.1%-20%, uniform loading of copper components on the nanosheet surface is achieved under inert and reducing atmospheres, forming stable nitrogen species activation sites. Further, in a system containing chloroauric acid and hydrochloric acid, at 80 mW / cm²... 2 -120mW / cm 2Photodeposition was performed under conditions of high light intensity and 5-30 min illumination time, enabling Au particles to be reduced and grown in situ on the nanosheet-Cu surface, thereby achieving interfacial coupling and synergistic distribution of Au and Cu components. Based on the above structural construction and parameter control, this application can form bimetallic active centers with clear functional division and spatial proximity on a two-dimensional nanosheet carrier. The Cu component preferentially participates in the nitrate reduction process, while Au particles preferentially promote carbon dioxide activation. The synergistic distribution of the two at the nanoscale effectively shortens the migration path of reaction intermediates and lowers the energy barrier of the CN coupling process. Simultaneously, under illumination, a localized surface plasmon resonance effect is generated between Au particles and the two-dimensional nanoantenna. The enhanced local electromagnetic field and high-energy hot carriers induced by this effect can significantly promote the interfacial charge transfer process. Therefore, even if the steady-state photoluminescence intensity change in the system is not significant, its essence does not originate from the enhancement of electron-hole recombination, but from the plasmon-enhanced chemiluminescence / reactive radiation process. This indicates that photogenerated carriers are more inclined to participate in surface catalytic reactions rather than recombination, thereby further suppressing side reactions and improving the selectivity of target product formation.

[0075] Furthermore, in the above process, the Au loading behavior was controlled by adjusting the photodeposition conditions to achieve a Cu to Au molar ratio of approximately 1:1 in the final catalyst, with the total metal loading controlled at approximately 3 wt%. This specific ratio and loading level not only ensured a match between the number of Au and Cu active sites, enabling a synergistic correspondence between carbon and nitrogen species activation sites in terms of quantity, thereby promoting effective coupling between intermediates, but also allowed Au particles at this loading level to form moderately dispersed nanostructures with strong plasmon response. This facilitated the generation of stable and efficient local electromagnetic field enhancement effects, further improving the generation and injection efficiency of hot carriers. In addition, by limiting the total metal loading, excessive agglomeration of metal particles and the obscuring of active sites on the nanosheet surface were avoided, maintaining the high specific surface area and interfacial accessibility of the two-dimensional nanostructure, thus optimizing the match between the plasmon enhancement effect and the bimetallic synergistic catalytic effect.

[0076] In this embodiment, a two-dimensional plasma nanoantenna is constructed through step S100 and then further peeled to obtain a single-layer or few-layer plasma nanosheet, which enables the material to have a high specific surface area and abundant surface active sites, while effectively shortening the transport path of photogenerated carriers and reducing the probability of electron-hole recombination.

[0077] In this embodiment, copper sources are introduced into plasma nanosheets and treated in a reducing atmosphere in steps S200 to S300 to obtain a nanosheet-Cu structure. This constructs activation sites for nitrogen species, primarily composed of copper, on the material surface, allowing them to preferentially participate in the nitrate reduction process. Further, in step S400, chloroauric acid is introduced and combined with light irradiation for in-situ reduction deposition, forming Au particles loaded on the surface of the nanosheet-Cu. The Au component preferentially promotes the activation of carbon sources such as carbon dioxide. Through the spatial proximity of Au and Cu at the nanoscale, the specialized activation and synergistic effect of carbon and nitrogen species are achieved, thereby constructing an Au-Cu bifunctional synergistic catalytic center and significantly improving the coupling efficiency of the CN coupling reaction.

[0078] In this embodiment, the molar ratio of copper ions to metal element M is 0.1%-20%, and the light intensity is 80mW / cm². 2 -120mW / cm 2 By synergistically regulating parameters such as illumination time (5-30 min), the deposition behavior of Au and the bimetallic interface structure are optimized, thereby promoting the effective separation of photogenerated electron-hole pairs and enhancing the injection of hot carriers and the interfacial charge transfer capability. Simultaneously, under the influence of plasmonic resonance, the local electromagnetic field is enhanced, further improving light energy utilization efficiency and reaction activation capability, thus significantly increasing the quantum efficiency and overall reaction kinetic rate of the photocatalytic reaction.

[0079] like Figure 2 As shown, the growth rate and loading of Au can be effectively controlled by adjusting the illumination time. Specifically, with the increase of illumination time, the Au / Ti molar ratio in the supported bimetallic two-dimensional nanocatalyst material continuously increases, and the increase in the Au / Ti molar ratio becomes larger when the illumination time is 20 min. This indicates that with the increase of illumination time, the growth rate and loading of Au particles in the supported bimetallic two-dimensional nanocatalyst material can be regulated, thereby regulating the loading of Au and Cu particles in the supported bimetallic two-dimensional nanocatalyst material.

[0080] In this embodiment, the illumination method for Au particle deposition can be xenon lamp irradiation or simultaneous excitation using monochromatic wavelengths of 365nm and 850nm, where the xenon lamp is a broadband light source. During the photodeposition of Au particles, the illumination method has a significant regulatory effect on their nucleation and growth sites. When a single wavelength is used for excitation, only plasmon resonance or energy level transitions matching that wavelength are excited, leading to the enrichment of photogenerated carriers at specific local sites, thus allowing Au to preferentially grow at a limited number of active sites. However, when multi-wavelength synergistic irradiation or a broadband light source is used, photons of different energies can simultaneously excite multiple electronic transition processes and plasmon resonance modes in the material system, significantly expanding the photoresponse range and enhancing the overall generation and migration capabilities of photogenerated carriers. Under these conditions, the distribution of electrons on the nanosheet surface is more uniform, allowing them to participate in Au growth at more potential active sites. 3+ The reduction reaction promotes uniform nucleation and growth of Au particles across the entire nanosheet surface, avoiding localized enrichment or uneven deposition. Therefore, this application preferably employs broadband light source irradiation or a combined 365nm and 850nm illumination method to achieve uniform loading of Au particles at all active sites.

[0081] like Figure 3 As shown, when excited by monochromatic light at 365 nm, Au particles in the bimetallic-based two-dimensional nanocatalyst material grow only at the edge active sites of the two-dimensional nanosheets. However, when excited by monochromatic light at 850 nm, Au particles in the bimetallic-based two-dimensional nanocatalyst material grow only at the in-plane active sites of the two-dimensional nanosheets. This indicates that using a broadband light source or a combined 365 nm and 850 nm light source can achieve uniform loading of Au particles at all active sites.

[0082] In a further embodiment, the plasma nanoantenna is Ti3C2T. x The metal element M is any one of Ti, Nb, or W, and different material systems exhibit differences in conductivity, photoresponse range, and surface chemical properties. Specifically, Ti3C2T... x MXene materials, represented by Nb₂C, possess excellent conductivity and surface functional groups, which can promote the rapid transport of photogenerated carriers and interfacial reactions. Meanwhile, WSe₂ exhibits good semiconductor light absorption characteristics, which is beneficial for expanding the photoresponse range and enhancing the photogenerated carrier generation efficiency. By selecting different types of plasmonic nanoantenna materials, it is possible to achieve synergistic regulation of light absorption performance, carrier migration capability, and interfacial catalytic reaction activity while ensuring the high specific surface area of ​​the two-dimensional structure and the exposure of active sites, thereby further optimizing the overall reaction efficiency of the Au-Cu bimetallic synergistic catalytic system.

[0083] In a further embodiment, the copper source is any one of copper acetate, copper nitrate, or copper sulfate. Different anionic systems regulate the solubility, coordination environment, and dispersion behavior of copper ions. Specifically, acetate ligands improve the dispersion of copper ions in organic / aqueous systems and promote their uniform loading on the nanosheet surface; nitrate ions have strong dissociation properties, which facilitate the rapid release of Cu. 2+ This improves loading efficiency; sulfate ions can regulate the release rate of copper ions to a certain extent, thereby inhibiting particle agglomeration caused by excessively rapid local deposition. By selecting different types of copper sources, the uniformity of copper component loading, particle size, and interfacial bonding state can be controlled, thereby optimizing the subsequent Au deposition behavior and Au-Cu interface structure, and improving the bimetallic synergistic catalytic effect and overall reaction stability.

[0084] In a further embodiment, the stirring speed is any value between 150 rpm and 250 rpm, and the stirring time is any value between 3 h and 4.5 h. That is, the stirring speed can be 150 rpm, 180 rpm, 200 rpm, 220 rpm, or 250 rpm, or any other value between 150 rpm and 250 rpm, and the stirring time can be 3 h, 3.5 h, 4 h, or 4.5 h, or any other value between 3 h and 4.5 h, so that the copper source is in a fully and gently mixed state in the plasma nanosheet dispersion system. Specifically, a moderate stirring speed can promote the uniform dispersion of copper ions in the solution and enhance their mass transfer process to the nanosheet surface, thereby improving the uniformity of copper component loading. It can also avoid nanosheet structure damage or local concentration fluctuations caused by excessively high stirring speeds, which is beneficial to maintaining the stability of the two-dimensional structure. At the same time, a stirring time of 3 h to 4.5 h can ensure sufficient contact and adsorption between copper ions and the active sites on the nanosheet surface, while avoiding excessive deposition or particle agglomeration caused by excessive time. By coordinating the control of stirring speed and time, the distribution and bonding strength of copper components on the nanosheet surface can be effectively optimized, thus providing a stable foundation for the subsequent uniform deposition of Au and the formation of Au-Cu interface structure.

[0085] In a further embodiment, the calcination temperature in the hydrogen atmosphere calcination treatment is any value between 250℃ and 350℃, and the calcination time is any value between 2.5h and 3.5h, so that the particle size of Cu particles in the nanosheet-Cu is any value between 4nm and 6nm. That is, the calcination temperature can be 250℃, 300℃, or 350℃, or any other value between 250℃ and 350℃, and the calcination time can be 2.5h, 3.0h, or 3.5h, or any other value between 2.5h and 3.5h, to prepare Cu particles with a particle size of 4nm, 4.5nm, 5nm, 5.5nm, or 6nm, or any other value between 4nm and 6nm. The above temperature and time range can ensure that the copper source is fully reduced and forms uniformly dispersed Cu particles on the surface of the nanosheet, and can also avoid particle growth or sintering agglomeration caused by excessively high temperature or excessive time, thereby maintaining the stability of the small-sized nanostructure.

[0086] Furthermore, Cu particles with sizes in the 4nm-6nm range exhibit excellent hot carrier extraction capabilities in plasma systems, enabling them to more efficiently capture and utilize high-energy electrons generated by plasma resonance, thereby significantly enhancing interfacial charge transfer efficiency. Simultaneously, Cu particles in this size range possess a high specific surface area and abundant low-coordination active sites, which is beneficial for enhancing the activation ability of reactions such as nitrate reduction. Through synergistic control of calcination temperature and time, the matching optimization between Cu particle size and plasma hot carrier extraction efficiency is achieved, thus providing a foundation for efficient electron transport and reaction in subsequent Au particle deposition and Au-Cu interfacial synergistic catalysis.

[0087] like Figure 4 As shown, a simulation experiment was conducted to investigate the effect of loaded bimetallic two-dimensional nanocatalysts with Cu particles of different sizes on carrier extraction. The results showed that Cu particles with a particle size of 4nm-6nm have extremely high efficiency in extracting plasmonic hot carriers.

[0088] Figure 5 This is a schematic flowchart of a method for preparing plasma nanosheets according to an embodiment of the present invention. Figure 6 This is an AFM morphology characterization image of plasma nanosheets according to one embodiment of the present invention. Figure 7 This is a cross-sectional view of the surface height of a plasma nanosheet according to an embodiment of the present invention.

[0089] like Figure 5 As shown, in a further embodiment, the plasma nanoantenna is Ti3C2T x When, step S100 includes the following steps:

[0090] Step S110: Ti3AlC2 powder is added to hydrofluoric acid solution for etching to remove the Al layer. After centrifugation and washing until neutral, the etched product is obtained.

[0091] Step S120: Add tetramethylammonium hydroxide aqueous solution to the etching product and sonicate to achieve peeling and dispersion. After standing, centrifuge to remove excess tetramethylammonium hydroxide.

[0092] Step S130: Collect the supernatant by centrifugation to obtain a few-layer Ti3C2T x The nanosheet dispersion was freeze-dried to obtain plasma nanosheets.

[0093] In this embodiment, when the plasma nanoantenna is Ti3C2T x In this study, the controllable preparation of a bulk MAX phase-to-phase two-dimensional few-layer MXene structure was achieved by etching, exfoliation, and fractionation of the Ti3AlC2 precursor. Specifically, in step S110, the Al layer was removed by hydrofluoric acid etching, allowing the layered structure to fully dissociate and expose the Ti3C2 framework. Simultaneously, washing to neutrality effectively removed residual acid and byproducts, improving material stability. In step S120, tetramethylammonium hydroxide was introduced for intercalation and ultrasonic exfoliation, which helped to widen the interlayer spacing and weaken interlayer forces, thereby achieving efficient exfoliation and dispersion to obtain structurally intact and well-dispersed two-dimensional nanosheets. In step S130, the supernatant was collected by centrifugation and fractionation, effectively screening out few-layer or even near-monolayer Ti3C2T... x Nanosheets are prepared by freeze-drying to prevent layer recombination and maintain their high specific surface area and open structure. Through the synergistic effect of the above multi-step process, a plasmonic nanoantenna with excellent conductivity, abundant surface functional groups, and good dispersion can be obtained, providing a structurally stable and highly active foundation for subsequent uniform loading of Cu and Au, interfacial coupling, and efficient transport of photogenerated carriers.

[0094] like Figure 6 and Figure 7 As shown, Figure 5 The preparation process shown successfully prepared a single-layer plasma nanosheet with a thickness of any value between 2.0 nm and 3.09 nm, such as 2.42 nm, 2.54 nm, 2.66 nm or 3.09 nm.

[0095] In a further embodiment, the concentration of the hydrofluoric acid solution is any value between 40wt% and 50wt%, i.e., the concentration of the hydrofluoric acid solution can be 40wt%, 42wt%, 44wt%, 46wt%, 48wt%, or 50wt%, or any other value between 40wt% and 50wt%. This provides sufficient etching power to fully peel off the Al layer, thereby forming a complete Ti3C2 layered framework. Simultaneously, compared to higher concentrations of hydrofluoric acid, this range effectively avoids excessive corrosion of the Ti-C host structure, reducing the problems of excessive defects or structural collapse. Furthermore, a moderate etching intensity is beneficial for forming appropriate amounts of -O, -OH, and -F terminal groups on the material surface, thereby improving the hydrophilicity and subsequent dispersion performance of the material, and enhancing its interfacial bonding ability with the copper source and gold precursor.

[0096] In a further embodiment, the concentration of HAuCl4 is any value between 5mM and 15mM, and the concentration of HCl is any value between 6M and 12M. That is, the concentration of HAuCl4 can be 5mM, 7mM, 10mM, 12mM, or 15mM, or any other value between 5mM and 15mM, and the concentration of HCl can be 6M, 8M, 10M, or 12M, or any other value between 6M and 12M. In this embodiment, by controlling the concentration of chloroauric acid within the range of 5mM to 15mM, the supply rate and nucleation density of the gold precursor in the system can be adjusted: a lower concentration is beneficial for forming better-dispersed Au particles, avoiding agglomeration caused by rapid nucleation; a higher concentration can increase the deposition rate and loading of Au, thereby achieving controllable adjustment of Au particle size and coverage density within a certain range. Simultaneously, by controlling the concentration of hydrochloric acid within the range of 6M to 12M, the acidity and ionic strength of the solution can be adjusted, which is beneficial for stabilizing AuCl4. - The precursor is reduced, thus decreasing its spontaneous reduction rate in solution, allowing Au particles to undergo selective reduction deposition primarily under illumination. Higher acidity also inhibits homogeneous nucleation of Au in solution, promoting heterogeneous deposition on the nanosheet-Cu surface and enhancing the interfacial bonding strength between Au and the support. Through synergistic regulation of the above concentration ranges, uniform loading, controllable size, and enhanced interfacial stability of Au particles on the nanosheet-Cu surface can be achieved.

[0097] The present invention also provides a supported bimetallic two-dimensional nanocatalyst material prepared by the above-described method for preparing supported bimetallic two-dimensional nanocatalyst materials.

[0098] Figure 8 This is a schematic diagram illustrating the principle of urea synthesis under pure sunlight catalysis using a bimetallic-based two-dimensional nanocatalytic material supported according to an embodiment of the present invention.

[0099] like Figure 8As shown, this invention also provides the application of the above-mentioned supported bimetallic two-dimensional nanocatalyst material in urea synthesis. In this embodiment, taking MXene material as an example, the working mechanism of the supported bimetallic two-dimensional nanocatalyst material for urea synthesis is as follows: MXene acts as a plasmonic nanoantenna, realizing highly directional photothermal and photochemical sensitization. Cu particles and Au particles in the nanosheet-Cu-Au are respectively preferentially and selectively adsorbed and activated, and then reduced to form NO3. - (Refer to arrow (1)) and HCO3 - (Refer to arrow (2)). Subsequently, activation is generated at the Au site. The C=O intermediate migrates to the adjacent Cu site (see arrow (3)), and adsorbs... NO species undergo efficient CN coupling (see arrow (4)) and are subsequently hydrogenated stepwise (see arrow (5)) to finally generate urea. That is, through the functional division and complementary synergistic effect of dual active sites, efficient solar-driven urea synthesis is achieved.

[0100] The technical solution of this application will be further described below with reference to specific embodiments.

[0101] In some embodiments, the preparation method of the supported bimetallic two-dimensional nanocatalytic material includes the following steps:

[0102] Step S100: Prepare a plasma nanoantenna and peel it off to obtain a plasma nanosheet with a single-layer or few-layer structure.

[0103] Step S200: Disperse plasma nanosheets in a solvent and add a copper source to prepare a first mixed solution;

[0104] Step S300: The first mixed solution is stirred in an inert gas environment, and then freeze-dried and calcined in a hydrogen atmosphere. The calcination temperature of the hydrogen atmosphere calcination treatment is any value between 250℃ and 350℃, and the calcination time is any value between 2.5h and 3.5h, to prepare Cu nanosheets with a particle size of any value between 4nm and 6nm.

[0105] Step S400: Dissolve Cu nanosheets in a solvent, add precursors HAuCl4 and HCl sequentially, mix, and transfer to a transparent glass cuvette. React under preset illumination conditions to reduce and grow Au particles in Cu nanosheets. After centrifugation and washing, prepare the bimetallic two-dimensional nanocatalyst material Cu-Au nanosheets. The molar ratio of copper ions in the copper source to metal element M in the plasma nanoantenna is any value between 0.1% and 20%, and the light intensity under the preset illumination conditions is 80 mW / cm².2 -120mW / cm 2 Any value in the range, with the illumination time being any value between 5 min and 30 min.

[0106] Example 1

[0107] The preparation method of supported bimetallic two-dimensional nanocatalytic materials includes the following steps:

[0108] Step S100: Preparation of Ti3C2T x Plasma nanoantennas were then peeled off to obtain Ti3C2T with a single-layer or few-layer structure. x Plasma nanosheets;

[0109] Step S200: Add 40 mg of Ti3C2T x MXene plasma nanosheets were dispersed in a solvent, and 1.4 mL of a 10 mM copper acetate solution was added to prepare a first mixed solution. The molar ratio of copper ions to metal element M in the plasma nanoantenna in the first mixed solution was 10%.

[0110] Step S300: The first mixed solution is stirred in an inert gas environment, and then freeze-dried and calcined in a hydrogen atmosphere. The calcination temperature of the hydrogen atmosphere calcination treatment is 300℃ and the calcination time is 3h, so as to obtain MXene-Cu with Cu particles with a particle size of 5nm.

[0111] Step S400: Dissolve 5 mg of MXene-Cu in a solvent, then add 100 µL of a 10 mM HAuCl4 precursor solution and 20 µL of a 12 M HCl solution sequentially. After mixing, transfer the mixture to a transparent glass cuvette and react under a preset illumination condition to reduce and grow Au particles in MXene-Cu. After centrifugation and washing, the supported bimetallic two-dimensional nanocatalyst material MXene-Cu-Au is prepared. The light intensity under the preset illumination condition is 100 mW / cm². 2 The illumination time is 10 minutes.

[0112] Example 2

[0113] The only difference between Example 2 and Example 1 is that the material of the plasma nanoantenna is WSe2.

[0114] Comparative Example 1

[0115] The only difference between Comparative Example 1 and Example 1 is that Au particles were not loaded by photodeposition in MXene-Cu, i.e. the bimetallic two-dimensional nanocatalyst material loaded is MXene-Cu.

[0116] Comparative Example 2

[0117] The only difference between Comparative Example 2 and Example 1 is that Au particles were deposited directly in MXene two-dimensional nanosheets to obtain a bimetallic two-dimensional nanocatalyst material called MXene-Au.

[0118] Comparative Example 3

[0119] The only difference between Comparative Example 3 and Example 1 is that the bimetallic two-dimensional nanocatalyst material is Mxene.

[0120] Comparative Example 4

[0121] The only difference between Comparative Example 4 and Example 1 is that the molar ratio of copper ions in the first mixed solution to metal element M in the plasma nanoantenna in step S200 is 0.05%.

[0122] Comparative Example 5

[0123] The only difference between Comparative Example 5 and Example 1 is that the molar ratio of copper ions in the first mixed solution to metal element M in the plasma nanoantenna in step S200 is 25%.

[0124] Comparative Example 6

[0125] The only difference between Comparative Example 6 and Example 1 is that the light intensity under the preset illumination condition in step S400 is 60 mW / cm². 2 .

[0126] Comparative Example 7

[0127] The only difference between Comparative Example 7 and Example 1 is that the light intensity under the preset illumination condition in step S400 is 140 mW / cm². 2 .

[0128] Comparative Example 8

[0129] The only difference between Comparative Example 8 and Example 1 is that the illumination time under the preset illumination conditions in step S400 is 2 minutes.

[0130] Comparative Example 9

[0131] The only difference between Comparative Example 9 and Example 1 is that the illumination time under the preset illumination conditions in step S400 is 40 minutes.

[0132] Figure 9 These are high-resolution transmission electron microscope images of the bimetallic-based two-dimensional nanocatalytic material supported according to Example 1 of the present invention. Figure 10 This is an energy dispersive X-ray spectral elemental distribution diagram of the bimetallic-based two-dimensional nanocatalyst material supported according to Example 1 of the present invention. Figure 11These are the X-ray diffraction patterns of the bimetallic-based two-dimensional nanocatalysts supported in Example 1 and Comparative Example 3 of the present invention. Figure 12 This is an electronic state characterization diagram of Ti in MXene-Cu-Au according to Embodiment 1 of the present invention. Figure 13 This is an electronic state characterization diagram of Cu in MXene-Cu-Au according to Embodiment 1 of the present invention. Figure 14 This is a high-resolution transmission electron microscope image of the bimetallic-based two-dimensional nanocatalytic material supported according to Example 2 of the present invention.

[0133] First, the performance of the supported bimetallic two-dimensional nanocatalyst MXene-Cu-Au prepared in Example 1 was characterized, and the results are shown in Table 1. Figures 9 to 11 The test results.

[0134] Table 1. ICP data of the bimetallic-based two-dimensional nanocatalyst material in Example 1

[0135]

[0136] As shown in Table 1, the Au and Cu concentrations in the supported bimetallic two-dimensional nanocatalyst material prepared in Example 1 were 23.3 ppm and 7.4 ppm, respectively. After conversion to molar ratio, the molar ratio of Cu to Au was approximately 1:1, and the total metal loading was 3 wt%.

[0137] like Figure 9 and Figure 10 As shown, high-resolution transmission electron microscopy images and energy-dispersive X-ray spectroscopy elemental plane distribution results confirm that the lattice spacings of 0.24 nm and 0.21 nm correspond to the Cu(111) and Au(111) crystal planes, respectively. The average diameter of Cu particles is 5.9 ± 0.7 nm, and the average diameter of Au particles is 15.1 ± 1.2 nm, indicating that Cu particles and Au particles are uniformly dispersed on MXene nanosheets.

[0138] like Figure 11 As shown, the X-ray diffraction pattern further confirmed the structural characteristics of MXene-Cu-Au: the diffraction peaks appearing at 37.5°, 43.4°, 63.1°, and 75.8° belong to the (111), (200), (220), and (311) crystal planes of Au, respectively, while the diffraction peak at 8.6° corresponds to the (002) crystal plane of MXene. This peak was shifted during the synthesis process due to the expansion of the interlayer z-axis. It should be noted that no obvious Cu diffraction peaks were observed due to the low loading and small particle size of Cu particles.

[0139] like Figure 12 and Figure 13As shown, in Example 1, the Ti element in MXene-Cu-Au is mainly titanium oxide with a valence state between +3 and +4, while the Cu element mainly exists in a metallic elemental state.

[0140] like Figure 14 As shown, in the supported bimetallic two-dimensional nanocatalytic material of Example 2, multiple metals are supported on WSe2 two-dimensional nanosheets.

[0141] Figure 15 The transient fluorescence spectra of the supported bimetallic two-dimensional nanocatalytic materials according to Example 1 and Comparative Example 1 of the present invention are shown below. Figure 16 This is the transient fluorescence spectrum of the supported bimetallic two-dimensional nanocatalytic material according to Comparative Example 2 of the present invention. Figure 17 The transient fluorescence spectrum of the bimetallic-based two-dimensional nanocatalytic material supported according to Comparative Example 3 of the present invention is shown.

[0142] To verify the charge extraction and separation capability of the bimetallic-based two-dimensional nanocatalytic material, steady-state and time-resolved transient photoluminescence tests were performed on MXene-Cu-Au from Example 1 and the control samples from Comparative Examples 1-3, yielding the following results: Figures 15 to 17 The test results are shown.

[0143] like Figures 15 to 17 As shown, although the steady-state photoluminescence intensity of each sample increased slightly, the time-resolved photoluminescence measurement results showed that the photoluminescence lifetime of MXene-Cu-Au in Example 1 ( ) is significantly longer than MXene-Cu in Comparative Example 1 ( ), MXene-Au in Comparative Example 2 ( ) and MXene in Comparative Example 3 ( The results show that long-lived charge carriers exist in MXene-Cu-Au, which also indicates that its nearly equal steady-state photoluminescence intensity is not actually due to recombination enhancement, but rather to the resonant plasmon enhancement effect of the chemiluminescence process.

[0144] Figure 18 The images show the Raman spectra of the bimetallic two-dimensional nanocatalysts supported in Examples 1 and 3 of the present invention.

[0145] To further verify the carrier extraction capability of the supported bimetallic two-dimensional nanocatalyst materials, the supported bimetallic two-dimensional nanocatalyst materials in Example 1 and Comparative Example 3 were irradiated under resonant wavelength illumination, resulting in the following... Figure 18 The test results are shown.

[0146] like Figure 18As shown, when using Raman-tagged molecules (Probe), the Raman shift of the MXene-Cu-Au sample in Example 1 was significantly stronger than that of the MXene sample in Comparative Example 3, indicating that the supported bimetallic two-dimensional nanocatalyst material in Example 1 can significantly improve its carrier extraction capability.

[0147] Figure 19 This is a comparison diagram of the photocurrent density of the bimetallic-based two-dimensional nanocatalyst material supported in the photoelectrocatalytic synthesis of urea according to Example 1, Comparative Example 1, and Comparative Example 3 of the present invention. Figure 20 This is a comparison of the photocurrent density of the bimetallic-based two-dimensional nanocatalyst materials supported in the photoelectrocatalytic synthesis of urea according to Example 1, Comparative Example 4, and Comparative Example 5 of the present invention. Figure 21 This is a comparison of the photocurrent density of the bimetallic-based two-dimensional nanocatalyst materials supported in the photoelectrocatalytic synthesis of urea according to Examples 1, 6, and 7 of the present invention. Figure 22 This is a comparison diagram of photocurrent density in photoelectrocatalytic urea synthesis using bimetallic-based two-dimensional nanocatalytic materials supported in Examples 1, 8, and 9 of the present invention.

[0148] To verify the application of the MXene-Cu-Au plasmonic catalyst in the co-reduction of carbonate and nitrate and subsequent CN coupling to synthesize urea, the photodriven catalytic performance of the supported bimetallic two-dimensional nanocatalysts in Example 1, Comparative Examples 1-2, and Comparative Examples 4-9 was systematically tested under photoelectrochemical and photocatalytic conditions, respectively. The results are as follows: Figures 19 to 22 The test results are shown. Photoelectrochemical urea synthesis experimental conditions: At room temperature, 0.9 M bicarbonate and 0.1 M nitrate in aqueous solution were used as carbon and nitrogen sources, respectively, and the supported bimetallic two-dimensional nanocatalyst materials from Examples 1, Comparative Examples 1-2, and Comparative Examples 4-9 were added.

[0149] like Figures 19 to 22 As shown, the current response of the catalyst was first evaluated using a linear sweep voltammetry method. The results showed that under simulated sunlight of 1 solar intensity, the photocurrent density of Example 1 was significantly higher than that of the control samples of Comparative Example 1 or Comparative Example 2. Furthermore, under the same illumination conditions, the Tafel slope of Example 1 was 388.9 mV dec. -1 It is lower than its dark-state 409.4 mV dec -1 It is also lower than that of Comparative Example 1 (503.0mV dec). -1 ) and Comparative Example 2 (993.3mV dec -1 Similarly, the photocurrent density and Tafel slope of Example 1 were significantly lower than those of Comparative Examples 4-9.

[0150] Figure 23This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the bimetallic-based two-dimensional nanocatalyst material supported according to Example 1 of the present invention. Figure 24 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalyst materials according to Example 1, Comparative Example 4, and Comparative Example 5 of the present invention. Figure 25 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalyst materials according to Example 1, Comparative Example 6, and Comparative Example 7 of the present invention. Figure 26 This is a comparison chart of the photoelectrocatalytic urea yield and selectivity performance of the supported bimetallic two-dimensional nanocatalyst materials according to Example 1, Comparative Example 8, and Comparative Example 9 of the present invention. Figure 27 This is a graph showing the photoelectrocatalytic stability of the supported bimetallic two-dimensional nanocatalytic material according to Example 1 of the present invention under light and dark conditions.

[0151] To quantitatively analyze the yield of photocatalyst-driven urea, colorimetric and urease decomposition methods were used to quantitatively detect the photoelectrocatalytic products, yielding results as follows: Figures 23 to 26 The test results are shown. First, the ammonia product was quantitatively detected using the indophenol blue spectrophotometric method. The specific steps are as follows: 2 mL of 1M NaOH solution containing 5 wt% salicylic acid and 5 wt% sodium citrate, 1 mL of 0.05M sodium hypochlorite solution, and 0.2 mL of 1 wt% sodium nitrosoferricyanide solution were added sequentially to 2.0 mL of electrolyte. After the mixture was allowed to stand at room temperature in the dark for 2 h, its absorbance was measured. Based on the standard curve established beforehand using a standard NH4Cl solution in 0.5M Na2SO4, the NH3 concentration was calculated using the absorbance at 655 nm. The urea yield was quantitatively determined using the urease decomposition method, as follows: 0.2 mL of a 5 mg / mL solution was added to 1.8 mL of electrolyte. -1 The urease solution was then reacted in a constant-temperature shaker at 37°C for 50 min. The concentrations of ammonia in the electrolyte, both the original concentration and the concentration generated from urea decomposition, were determined using the indophenol blue spectrophotometric method described above. Theoretically, 1 mole of urea can decompose to produce 2 moles of ammonia. Therefore, the amount of urea generated was calculated based on the change in ammonia concentration in the electrolyte before and after urease decomposition.

[0152] like Figure 23 As shown, in the photoelectrocatalytic reaction system simulating sunlight irradiation, the urea concentration increased significantly with reaction time under all applied bias voltages. The urea concentration exhibited a clear parabolic dependence with respect to the applied bias voltage: the highest urea yield of 301.5 mmol gcat was reached at a bias voltage of -1.45 V (vs Ag / AgCl). -1 h -1 This value is comparable to that of the most advanced urea synthesis catalysts reported in recent literature, and significantly higher than -1.3V (81.8 mmol gcat).-1 h -1 ) and -1.6V (222.3mmol gcat) -1 h -1 Yield under bias voltage. To evaluate urea selectivity, the formation of byproducts ammonia and hydrogen was also detected. After considering the main byproducts, a decreasing trend in urea selectivity was observed with a negative bias voltage: the highest selectivity (69.7%) was observed at -1.3V bias voltage, which was higher than the selectivity at -1.45V (56.0%) and -1.6V (47.7%) bias voltages. The photoelectrocatalytic urea selectivity of nearly 70% is also comparable to the highest known performance.

[0153] The supported bimetallic two-dimensional nanocatalysts in Comparative Examples 4-9 were tested for urea catalytic synthesis under a bias voltage of -1.45V (vs Ag / AgCl), and the results were as follows. Figures 24 to 26 The test results.

[0154] like Figures 24 to 26 As shown, the supported bimetallic two-dimensional nanocatalysts in Example 1 and Comparative Examples 4-9 all exhibit corresponding catalytic selectivity for urea synthesis. However, the urea concentration obtained by the supported bimetallic two-dimensional nanocatalyst in Example 1 for urea synthesis is much higher than that in Comparative Examples 4-9. This indicates that the deposition conditions of Au particles and the molar ratio of Cu to titanium must be within the range specified in this application to prepare supported bimetallic two-dimensional nanocatalysts with high catalytic activity and selectivity.

[0155] like Figure 27 As shown, the catalytic stability was evaluated by long-term photoelectrochemical measurements under continuous illumination and applied bias. The results showed that MXene-Cu-Au could maintain a stable photocurrent intensity, and its current value showed a significant upward trend over time. The results indicate that the supported bimetallic two-dimensional nanocatalyst material in Example 1 has good stability, and also indicate that plasmon photothermal conversion may produce a thermal effect, which leads to a continuous increase in the system temperature.

[0156] Figure 28 These are pulse curves of the supported bimetallic two-dimensional nanocatalyst materials in the nitrate reaction system according to Comparative Examples 1 and 2 of the present invention. Figure 29 These are pulse curves of the supported bimetallic two-dimensional nanocatalyst materials in the bicarbonate reaction system according to Comparative Examples 1 and 2 of the present invention. Figure 30 These are pulsed chemisorption-conversion measurement curves of the supported bimetallic two-dimensional nanocatalyst material in the nitrate reaction system under light and dark conditions, according to Comparative Example 1 of the present invention. Figure 31The graphs show the pulsed chemisorption-conversion measurements of the supported bimetallic two-dimensional nanocatalyst material in the bicarbonate reaction system under light and dark conditions, as described in Comparative Example 2 of the present invention.

[0157] To elucidate the respective roles of Cu and Au sites in the bimetallic-based two-dimensional nanocatalyst material during the pure photocatalytic synthesis of urea, pulsed chemisorption-conversion experiments were conducted, yielding the following results: Figures 22 to 25 The test results are shown. The experimental procedure included: batch-wise pulsed injection of 1 μM trace amounts of reactant into the catalytic reaction aqueous solution, and monitoring the transient current response under non-reaction-controlled kinetics to analyze interfacial chemisorption and surface reaction kinetics. In blank reaction buffer, catalysts corresponding to single active sites, such as MXene-Au and MXene-Cu, were tested using nitrate or bicarbonate as pulsed reactants.

[0158] like Figures 28 to 29 As shown, obvious current density pulses were immediately observed after the addition of reactants, indicating that both Au and Cu particles can adsorb and activate the two reactants to a certain extent to promote their conversion. However, the pulse intensities of the bimetallic-based two-dimensional nanocatalysts in Comparative Examples 1 and 2 showed significant differences in different reactant systems: when nitrate was added, the system containing the bimetallic-based two-dimensional nanocatalyst in Comparative Example 1 exhibited a higher pulse intensity; while when bicarbonate was added, the system containing the bimetallic-based two-dimensional nanocatalyst in Comparative Example 1 exhibited a higher pulse intensity. Detailed analysis of the slopes of the rising and falling segments of each pulse further confirmed that Cu particles consistently exhibited higher adsorption and conversion kinetics for nitrate, and Au particles for bicarbonate.

[0159] like Figure 30 and Figure 31 As shown, to verify the effect of illumination, pulsed chemisorption-conversion measurements were also performed under dark conditions and simulated sunlight conditions. The results showed that under illumination, the pulse intensity and rise slope of MXene-Cu for nitrate in Comparative Example 1 and MXene-Au for bicarbonate in Comparative Example 2 were significantly increased, indicating that photo-mediated interaction significantly enhanced their selective chemisorption and activation behavior. These results confirm that the Cu and Au active sites have highly complementary effects on the activation of nitrate and bicarbonate, respectively, and hold promise for synergistic coupling in bimetallic systems.

[0160] Figure 32 This is a urea yield-time curve of the bimetallic-based two-dimensional nanocatalytic material used in urea synthesis according to Example 1 of the present invention.

[0161] Under a solar equivalent light intensity, i.e., a light intensity of 100 mW / cm²,2 Under broadband xenon lamp irradiation, the photocatalytic synthesis of urea via the co-reduction of nitrate and bicarbonate was subsequently conducted using the bimetallic two-dimensional nanocatalyst MXene-Cu-Au prepared in Example 1. The amount of urea produced during the reaction was quantitatively analyzed using a colorimetric assay with a chromogenic solution and a combined colorimetric assay with urea hydrolase. Figure 26 The test results are shown.

[0162] like Figure 32 As shown, the MXene-Cu-Au supported bimetallic two-dimensional nanocatalyst material prepared in Example 1 achieved a considerable urea yield when used to produce urea under pure light irradiation. Its concentration continuously increased with reaction time; after 2 hours of irradiation, the urea yield after 3 hours approached 8 mg / L solution, with the converted yield reaching a maximum of 79.0 μmol gcat. -1 h -1 The average yield was 52.2 μmol gcat. -1 h -1 .

[0163] In summary, through comparison of the examples and comparative examples and multidimensional characterization results, it is evident that the MXene-Cu-Au bimetallic two-dimensional nanocatalyst material constructed in this application exhibits significant advantages in both structure and performance. Inductively coupled plasma atomic emission spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy results show that Au and Cu are uniformly loaded in a molar ratio of approximately 1:1, forming spatially adjacent synergistic active sites. Photoluminescence and Raman spectroscopy tests indicate that this system possesses a longer carrier lifetime and stronger carrier extraction capability; its steady-state luminescence intensity is not due to recombination enhancement but rather caused by plasmon resonance. Performance test results further demonstrate that Example 1 outperforms the single-component and control samples deviating from the parameter range in terms of photocurrent density, reaction kinetics, and urea yield and selectivity, indicating that only under the metal ratio and photodeposition conditions specified in this application can effective matching of charge behavior and reaction process be achieved. Simultaneously, pulsed experiments verified that Cu and Au respectively dominate nitrate and carbon source activation, and the two synergistically promote CN coupling. In summary, this application achieves a unified effect of plasmon enhancement and bimetallic synergy through the synergistic regulation of structure and parameters, thereby significantly improving the performance of urea synthesis.

[0164] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0165] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a bimetallic-based two-dimensional nanocatalytic material, characterized in that, Includes the following steps: Plasma nanoantennas are prepared and then peeled off to obtain plasma nanosheets with a single-layer or few-layer structure. The plasma nanoantennas are two-dimensional nanoantennas with plasma response capability. The plasma nanosheets were dispersed in a solvent, and a copper source was added to prepare a first mixed solution. The first mixed solution was stirred in an inert gas environment, and then freeze-dried and calcined in a hydrogen atmosphere to prepare nanosheet-Cu. The nanosheet-Cu was dissolved in the solvent, and the precursors HAuCl4 and HCl were added sequentially. After mixing, the mixture was reacted under preset light conditions to reduce and grow Au particles in the nanosheet-Cu. After centrifugation and washing, the supported bimetallic two-dimensional nanocatalytic material nanosheet-Cu-Au was prepared. The molar ratio of copper ions in the copper source to the metal element M in the plasma nanoantenna is any value between 0.1% and 20%, and the light intensity under the preset illumination condition is 80 mW / cm². 2 -120mW / cm 2 Any value in the range, with a light exposure time of any value between 5 min and 30 min; The plasma nanoantenna is a Ti3C2T. x Any one of Nb2C or WSe2.

2. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to claim 1, characterized in that, The copper source is any one of copper acetate, copper nitrate, and copper sulfate.

3. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to claim 1, characterized in that, The stirring speed is any value between 150 rpm and 250 rpm, and the stirring time is any value between 3 h and 4.5 h.

4. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to claim 1, characterized in that, The calcination temperature for the hydrogen atmosphere calcination treatment is any value between 250℃ and 350℃, and the calcination time is any value between 2.5h and 3.5h, so that the particle size of Cu particles in the nanosheet-Cu is any value between 4nm and 6nm.

5. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to claim 1, characterized in that, The plasma nanoantenna is the Ti3C2T x The fabrication of the plasma nanoantenna includes the following steps: Ti3AlC2 powder was added to hydrofluoric acid solution for etching to remove the Al layer. After centrifugation and washing until neutral, the etched product was obtained. Add an aqueous solution of tetramethylammonium hydroxide to the etching product and sonicate to achieve peeling and dispersion. After standing, centrifuge to remove excess tetramethylammonium hydroxide. The supernatant was collected by centrifugation to obtain a few-layer Ti3C2T. x The nanosheet dispersion is subjected to the freeze-drying process described above to obtain the plasma nanosheets.

6. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to claim 5, characterized in that, The concentration of the hydrofluoric acid solution is any value between 40wt% and 50wt%.

7. The method for preparing the supported bimetallic-based two-dimensional nanocatalytic material according to any one of claims 1-6, characterized in that, The concentration of HAuCl4 is any value between 5mM and 15mM, and the concentration of HCl is any value between 6M and 12M.

8. A method for preparing a supported bimetallic two-dimensional nanocatalyst material according to any one of claims 1-7.

9. The application of the supported bimetallic two-dimensional nanocatalytic material as described in claim 8 in urea synthesis.

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