Surface oxidation monatomic nano-alloy catalyst as well as preparation method and application thereof

Abstract

The invention discloses a surface oxidation monatomic nano-alloy catalyst as well as a preparation method and application thereof, and belongs to the technical field of advanced nano-energy materials and electro-catalysis. A surface-oxidized monatomic nano-alloy catalyst comprises a hydroxylated carbon nanotube carrier and bimetallic nano-alloy particles loaded on the hydroxylated carbon nanotube carrier, in the bimetallic nano-alloy particles, non-noble metal elements are dispersed in noble metal nano-particles in a monatomic form, the size of the bimetallic nano-alloy particles is 3-4 nm, and the surface-oxidized monatomic nano-alloy catalyst is prepared from a surface-oxidized monatomic nano-alloy catalyst. An oxide layer with the thickness of 0.3-0.6 nm is arranged on the surface of the bimetallic nano-alloy particle; the loading amount of the noble metal is 5-15wt%. Ruthenium and other non-noble metal elements are alloyed and anchored on the carbon material substrate, the conductivity of the catalyst can be greatly improved, the size of alloy particles is accurately controlled within the range of 3-4 nm, active sites can be exposed to the maximum extent, and structural stability is considered.

Description

Technical Field

[0001] This invention relates to a surface oxidation single-atom nanoalloy catalyst, its preparation method, and its application. Specifically, it relates to a catalyst in which copper single atoms are distributed in nano-ruthenium metal particles to achieve uniform surface oxidation, its preparation method, and its application, belonging to the field of advanced nano-energy materials and electrocatalysis technology. Background Technology

[0002] Hydrogen energy, as a green and efficient secondary energy source, is considered the best alternative to fossil fuels due to its high energy density and zero carbon emissions. Against this backdrop, producing "green hydrogen" through water electrolysis has become one of the core pathways to promote energy structure transformation and achieve carbon neutrality. The large-scale application of hydrogen production through water electrolysis is highly dependent on the development of catalysts for the hydrogen evolution reaction. Currently, commercial electrolyzers generally use platinum-based catalysts, but their high cost and global scarcity constrain the sustainable development of the hydrogen energy industry.

[0003] To reduce reliance on platinum, researchers have turned their attention to other precious metals, among which ruthenium is considered one of the most promising alternatives due to its relatively low price (about one-third that of platinum) and suitable hydrogen adsorption free energy. However, single ruthenium nanoparticles suffer from problems such as dissolution, migration, and Ostwald ripening in the working environment of a proton exchange membrane electrolyzer, resulting in poor stability. Furthermore, its intrinsic activity still has room for improvement. However, existing synthetic methods struggle to synergistically achieve the ideal alloy electronic structure, suitable nanoscale size, and controllable surface oxidation state in a single system, necessitating the development of a green synthetic strategy that integrates these advantages.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] This invention provides a soft chemical method for preparing in-situ oxidized nanoalloy catalysts on hydroxylated carbon nanotubes (i.e., a method for preparing surface-oxidized single-atom nanoalloy catalysts). Using ethanol or other liquid phases as the reaction medium, a metal salt precursor is reduced by two-stage pulsed laser irradiation, achieving the synthesis of nanoalloys and their firm anchoring on the carbon nanotube surface in one step. This method is carried out at room temperature and pressure, requiring no subsequent heat treatment, and can form an oxide layer with a controllable electronic structure in situ on the alloy surface, thereby effectively optimizing catalytic performance. The entire process is green and highly efficient.

[0006] Meanwhile, the present invention provides a surface oxidation single-atom nano-alloy catalyst.

[0007] Meanwhile, this invention provides an application of a surface oxidation single-atom nano-alloy catalyst.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a surface-oxidized single-atom nano-alloy catalyst includes the following steps: uniformly dispersing hydroxylated carbon nanotubes, ruthenium ion salts, and copper ion salts in ethanol to obtain a uniform suspension; subjecting the suspension to two-stage pulsed laser repeated irradiation using a neodymium-doped yttrium aluminum garnet laser, thereby forming nano-alloy particles with a size of approximately 3-4 nm and a uniformly oxidized surface on the hydroxylated carbon nanotubes by metal salt ions.

[0009] Preferably, multi-walled carbon nanotubes are added to concentrated nitric acid and refluxed at 120°C for 8 hours. After reflux, they are washed repeatedly by centrifugation with deionized water to obtain hydroxylated carbon nanotubes.

[0010] Preferably, the ruthenium ion salt is any one of ruthenium chloride, ruthenium nitrate, and ruthenium acetylacetonate.

[0011] Preferably, the copper ion salt is any one of copper chloride, copper nitrate, and copper acetate.

[0012] Preferably, ethanol can be replaced with reducing solvents such as methanol or ethylene glycol.

[0013] Preferably, the hydroxylated carbon nanotubes, ruthenium ion salt, and copper ion salt are ultrasonically dispersed in a solvent for a time of not less than 1 hour and a temperature of not more than 40°C.

[0014] Preferably, the pulsed laser irradiation step is performed at room temperature and atmospheric pressure.

[0015] Preferably, the frequency of the pulsed laser is 10-30 Hz.

[0016] Preferably, the laser energy of the laser is adjusted to 5-20 mJ.

[0017] Preferably, ruthenium ion salts can be replaced with precious metal salts such as silver ion salts, palladium ion salts, and platinum ion salts.

[0018] Specifically, a method for preparing a surface-oxidized single-atom nano-alloy catalyst includes the following steps: hydroxylated carbon nanotubes, ruthenium salt, and copper salt are dispersed in a reducing solvent to form a uniform suspension. The suspension is then subjected to two-stage repeated irradiation using a pulsed laser at room temperature and pressure. Each stage has a pulse energy of 5-20 mJ, a repetition frequency of 10-30 Hz, a pulse width of 5-10 ns, and an irradiation time of 30-90 minutes. The two stages are intermittently stirred and cooled for 10-15 minutes to achieve sufficient reduction, alloying, and anchoring of metal ions on the carbon nanotube surface. After the reaction is complete, the solid product is washed and dried to obtain the surface-oxidized single-atom nano-alloy catalyst.

[0019] Preferably, the reducing solvent is ethanol, methanol, or ethylene glycol.

[0020] A surface-oxidized single-atom nanoalloy catalyst, wherein a metal element is dispersed in the form of single atoms in another metal nanoparticle, the nanoparticles having a size of 3-4 nm and being uniformly loaded on hydroxylated carbon nanotubes, and the surface of the nanoalloy has an oxide layer of 0.3-0.6 nm thickness.

[0021] A surface-oxidized single-atom nanoalloy catalyst includes a hydroxylated carbon nanotube support, bimetallic nanoalloy particles supported on the support, wherein one metal element is dispersed in the lattice of another metal in single-atom form, the nanoparticles have a size of 3-4 nm, the surface of the nanoalloy has an oxide layer of 0.3-0.6 nm thickness, the oxide layer is composed of amorphous CuO, and the ruthenium loading is 5-15 wt%.

[0022] A surface-oxidized single-atom nanoalloy catalyst, wherein copper is dispersed in the lattice of ruthenium metal in the form of single atoms.

[0023] Application of a surface-oxidized single-atom nano-alloy catalyst in the hydrogen evolution reaction of water electrolysis, at a current density of 10 mA / cm² 2 The overpotential is below 40 mV, the Tafel slope is less than 30 mV / dec, and the amount of ruthenium used is reduced by 50%-80% compared with traditional ruthenium-based catalysts (Aladdin, ruthenium dioxide).

[0024] Specifically, a method for preparing a surface-oxidized single-atom nano-alloy catalyst includes the following steps: S01, weigh 100-300 mg of multi-walled carbon nanotubes and place them in a round-bottom flask. Add 50-200 mL of concentrated nitric acid (the concentration of which is greater than 68%). Reflux the reaction in an oil bath at 110-150℃ for 6-10 hours. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water by centrifugation until the filtrate is neutral. Then freeze-dry for 10-16 hours to obtain hydroxylated multi-walled carbon nanotubes. Take 6-10 mg of hydroxylated multi-walled carbon nanotubes prepared by S01, 2-4 mg of ruthenium salt and 2-4 mg of copper salt, and place them together in a 50-100 mL quartz reaction flask; add 10-20 mL of reducing solvent as a solvent, and sonicate at 120-180W power for no less than 1 hour and at a temperature no higher than 40℃ to form a uniform and stable black suspension. S03, the above suspension is placed in the laser path and irradiated for 30-90 minutes using a neodymium-doped yttrium aluminum garnet pulsed laser with a pulse energy of 5-20 mJ, a repetition frequency of 10-30 Hz, and a pulse width of 5-10 ns. After the first irradiation, the mixture is stirred and cooled for 10-15 minutes before a second laser irradiation. Mechanical stirring is maintained throughout the reaction at a stirring rate of 500-800 rpm. After the reaction, the product is washed several times with ethanol and deionized water and freeze-dried for 10-16 h to obtain a surface-oxidized single-atom nano-alloy catalyst.

[0025] Application of a surface-oxidized single-atom nano-alloy catalyst in the hydrogen evolution reaction of water electrolysis.

[0026] A method for using a surface-oxidized single-atom nano-alloy catalyst, the preparation method of which uses the surface-oxidized single-atom nano-alloy catalyst as the working electrode is as follows: Weigh 3-6 mg of surface-oxidized single-atom nano-alloy catalyst powder and place it in a solution prepared by isopropanol, ethanol and Nafion in a ratio of 10:10:1 in 1-2 mL, and ultrasonically disperse for 30-60 minutes to obtain a uniformly dispersed catalyst ink; Take 5-10 μL of the catalyst ink in three- to four portions each time and uniformly drop it onto the working electrode (preferably a glassy carbon electrode with a diameter of 4 mm), and let it air dry at room temperature.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) This invention provides a method for in-situ preparation of ruthenium copper oxide single-atom alloy on hydroxylated carbon nanotubes. The hydroxylation treatment not only improves the dispersibility of carbon nanotubes in solvents, but also forms abundant defect sites on their surface, providing an ideal substrate for metal anchoring. By irradiating the precursor suspension with a two-stage pulsed laser, the instantaneous reduction and alloying of metal ions are achieved in a local microenvironment, and the strong anchoring effect of the defect sites is used to achieve a firm loading of nanoparticles.

[0028] (2) This invention not only successfully achieved uniform dispersion of copper in ruthenium nanolattice in the form of single atoms, but also utilized this unique reaction environment to construct an oxide layer with precisely controllable electronic structure in situ on the surface of the alloy particles, and the thickness of the oxide layer is only 0.3-0.6 nm. Finally, the size of the single-atom alloy is 3-4 nm, maximizing the exposure of active sites while taking into account structural stability.

[0029] (3) The entire preparation process does not require a high temperature and high pressure environment, nor does it rely on any surfactants or stabilizers, thus avoiding the introduction of impurities and subsequent purification steps. It is an efficient and green soft chemical synthesis route. The obtained catalyst exhibits significantly better activity and stability than commercial platinum carbon in the water electrolysis hydrogen evolution reaction, and has broad application potential in the fields of optics, sensing and energy conversion.

[0030] This invention discloses a surface-oxidized single-atom nano-alloy catalyst, its preparation method, and its applications. The method includes: dispersing hydroxylated carbon nanotubes, ruthenium salt, and copper salt in a reducing solvent such as ethanol to form a uniform suspension; irradiating the suspension using a two-stage pulsed laser irradiation process at room temperature and pressure; achieving instantaneous reduction, alloying, in-situ oxidation, and anchoring of metal ions on the carbon nanotube surface in one step; and forming nano-alloy particles with a size of 3-4 nm, wherein copper is dispersed in the ruthenium nanolattice in a single-atom form, and an oxide layer of 0.3-0.6 nm thickness is formed in-situ on the alloy surface. This method is simple, green, and efficient, requiring no high temperature, high pressure, or surfactants. The prepared catalyst exhibits excellent catalytic activity and stability in the hydrogen evolution reaction of water electrolysis, showing promising application prospects.

[0031] This invention alloys ruthenium with other non-precious metal elements and anchors it on a carbon substrate, which can significantly improve the conductivity of the catalyst. Precisely controlling the alloy particle size within the 3-4 nm range maximizes the exposure of active sites while maintaining structural stability. Furthermore, constructing a uniform oxide layer on the alloy surface can further modulate the interfacial electronic structure, optimize the d-band center position of the catalytic sites, and adjust the adsorption energy for hydrogen. Attached Figure Description

[0032] Figure 1 Transmission electron microscope image of the surface ruthenium oxide copper single-atom nanoalloy prepared in Example 1; Figure 2 The X-ray diffraction pattern of the surface ruthenium oxide copper single-atom nanoalloy prepared in Example 1; Figure 3 Linear sweep voltammetry curve of the surface ruthenium oxide copper single-atom nanoalloy prepared in Example 1 when used for electrocatalytic hydrogen evolution test; Figure 4 The stability test results of the surface ruthenium oxide copper single-atom nanoalloy prepared in Example 1 when used in the electrocatalytic hydrogen evolution test; Figure 5 Linear sweep voltammetry curves of the surface ruthenium oxide copper single-atom nanoalloy prepared in Example 2 when used for electrocatalytic hydrogen evolution testing. Detailed Implementation

[0033] The method for in-situ preparation of ruthenium copper oxide single-atom alloy on hydroxylated carbon nanotubes provided by this invention is described in detail below. Unless otherwise specified in the examples of this invention, all operations were performed under conventional experimental conditions or according to the conditions recommended by the manufacturers of the instruments and reagents used. All reagents and instruments, unless otherwise specified, are conventional products in the art and can be purchased through publicly available channels.

[0034] This invention utilizes a two-stage pulsed laser irradiation method to reduce dispersed ruthenium and copper ions into nanoalloy particles with a size of only 3-4 nm in reducing solvents such as ethanol. These nanoalloy particles achieve a unique structure where copper atoms are uniformly distributed as single atoms within the ruthenium nanolattice. Furthermore, taking advantage of the fact that copper is more easily oxidized than ruthenium, a uniform oxide layer forms in situ on the surface of the alloy particles during the synthesis process, enabling the regulation of the catalyst's electronic structure. More importantly, this unique surface oxidation feature effectively optimizes the d-band electronic structure of the active centers, lowers the reaction energy barrier, and significantly improves catalytic performance. The entire preparation process is carried out at room temperature and pressure, requiring no subsequent heat treatment, thus avoiding the particle agglomeration and size inhomogeneity problems common in traditional methods, providing a novel green approach for the preparation of high-performance catalysts. Example 1

[0035] In this embodiment, the electrolyte used for electrocatalytic hydrogen production testing was a 1 M KOH solution. The auxiliary electrode was an 8 mm diameter carbon rod, and the reference electrode was Hg / HgO. The preparation method of the surface-oxidized single-atom nanoalloy as the working electrode was as follows: 3 mg of catalyst powder was weighed and placed in 1 mL of a solution prepared with isopropanol, ethanol, and Nafion in a 10:10:1 ratio. The solution was ultrasonically dispersed for 30 minutes to obtain a uniformly dispersed catalyst ink. Five μL of the suspension was then evenly drop-coated onto a 4 mm diameter glassy carbon electrode in three separate applications. After air-drying at room temperature, the working electrode was obtained, with a catalyst loading of approximately 0.35 mg / cm³. 2 Linear sweep voltammetry (LSV) measurements were performed on a Metrohm AutoLab electrochemical workstation at a scan rate of 5 mV / s. The current density in the LSV curves was 10 mA / cm². 2 The corresponding potential is the overpotential of the hydrogen evolution reaction. The Tafel slope is obtained by converting LSV data into a curve of overpotential versus the logarithm of the absolute value of current density, fitting it in the kinetically controlled linear region, and the slope of the resulting straight line is the Tafel slope.

[0036] A surface-oxidized ruthenium-copper single-atom nano-alloy catalyst for electrocatalytic hydrogen evolution (i.e., a surface-oxidized single-atom nano-alloy catalyst) is prepared by the following steps: (1) Weigh 200 mg of multi-walled carbon nanotubes and place them in a round-bottom flask. Add 100 mL of concentrated nitric acid (68%). Reflux the reaction at 120 °C in an oil bath for 8 hours. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water by centrifugation until the filtrate is neutral. Then freeze-dry for 12 hours to obtain hydroxylated multi-walled carbon nanotubes.

[0037] (2) Take 8 mg of the hydroxylated multi-walled carbon nanotubes prepared in step (1), 3 mg of ruthenium chloride and 3 mg of copper acetate, and place them together in a 50 mL quartz reaction flask. Add 15 mL of anhydrous ethanol as a solvent and sonicate at 120 W for 1 hour to form a uniform and stable black suspension.

[0038] (3) The above mixture was placed in the laser path and irradiated for 30 minutes using a neodymium-doped yttrium aluminum garnet pulsed laser with a pulse energy of 10 mJ, a repetition frequency of 20 Hz, and a pulse width of 7 ns. After 30 minutes of irradiation, the mixture was stirred and cooled for 10 minutes before a second laser irradiation. The laser irradiation process was repeated twice for a total of 60 minutes. Mechanical stirring was maintained throughout the reaction at a stirring rate of 600 rpm. After the reaction, the product was washed several times with ethanol and deionized water and freeze-dried for 12 h to obtain the surface-oxidized ruthenium copper single-atom nanoalloy catalyst supported on hydroxylated carbon nanotubes (i.e., the surface-oxidized single-atom nanoalloy catalyst).

[0039] A surface-oxidized single-atom nanoalloy catalyst includes a hydroxylated carbon nanotube support, bimetallic nanoalloy particles supported on the hydroxylated carbon nanotube support, wherein copper is dispersed in ruthenium nanoparticles in the form of single atoms in the bimetallic nanoalloy particles, the size of the bimetallic nanoalloy particles is 3-4 nm, and the surface of the bimetallic nanoalloy particles has an amorphous CuO oxide layer of about 0.5 nm thickness; the loading of ruthenium is 10 wt%.

[0040] Application of a surface-oxidized single-atom nano-alloy catalyst in the hydrogen evolution reaction of water electrolysis.

[0041] A method for using a surface-oxidized single-atom nano-alloy catalyst, the preparation method of using the surface-oxidized single-atom nano-alloy catalyst as the working electrode is as follows: Weigh 3 mg of surface-oxidized single-atom nano-alloy catalyst powder and place it in a solution prepared by isopropanol, ethanol and Nafion in a ratio of 10:10:1 in 1 mL, and ultrasonically disperse for 30 minutes to obtain a uniformly dispersed catalyst ink; Take 5 μL of catalyst ink three times, each time and uniformly drop it onto the working electrode, and let it air dry at room temperature to obtain the final product.

[0042] Figure 1 This is a transmission electron microscope image of the catalyst prepared in Example 1. As can be seen from the image, the surface-oxidized ruthenium-copper single-atom nanoalloy is well dispersed on the surface of the carbon nanotube support in the form of uniformly sized nanoparticles. The carbon nanotubes have a diameter of approximately 20 nm, while the supported alloy particles have a diameter concentrated in the range of 3-4 nm. This ultra-small size and uniform distribution structure facilitates maximum exposure of active sites while maintaining the structural stability of the material.

[0043] Figure 2The X-ray diffraction pattern of the product obtained in Example 1 is shown. The sample shows a characteristic diffraction peak of the carbon nanotube (002) crystal plane at 2θ ≈ 26°, while no obvious diffraction peaks of metal or alloy crystals are observed. This is consistent with the broadening effect of the diffraction signal caused by the ultrafine size (3–4 nm) of the alloy particles, which confirms the successful preparation of the ultrafine nano-alloy structure.

[0044] Figure 3 The image shows the linear sweep voltammetry curve of the catalyst in Example 1 during the electrocatalytic hydrogen evolution reaction. Due to the extremely small alloy particle size, sufficient exposure of active sites, and the effective optimization of the electronic structure by the surface oxide layer, this catalyst exhibits excellent hydrogen evolution performance: at a current density of 10 mA / cm²... 2 The overpotential is as low as 27.5 mV, with a Tafel slope of 21 mV / dec; when the potential is increased to 200 mV, the current density reaches as high as 291.7 mA / cm². 2 It is significantly superior to conventional platinum / carbon catalysts (Johnson Matthey, 20% Pt / C).

[0045] Figure 4 The results show the stability test of the catalyst in Example 1 during the hydrogen evolution reaction. After 1000 cycles of cyclic voltammetry, its catalytic activity remained good. Furthermore, in the higher potential range (> 0.156 V), the post-cycle catalytic activity was even better than the initial value, which may be due to further optimization of the alloy surface structure during the reaction, indicating that the catalyst possesses excellent electrochemical stability and operational durability. Example 2

[0046] A surface-oxidized ruthenium copper single-atom nano-alloy catalyst for electrocatalytic hydrogen evolution is prepared in a manner similar to that of Example 1, except that in Example 1, the 3 mg copper acetate in step (2) is changed to 2 mg copper acetate, while keeping the other conditions the same.

[0047] In this embodiment, the oxide layer is approximately 0.3 nm thick; the oxide layer is amorphous CuO.

[0048] Figure 5 This is a comparison of the linear sweep voltammetry curves of the surface ruthenium oxide copper single-atom nanoalloys prepared in Example 2 and Example 1. The catalyst obtained in Example 2 was subjected to a current density of 10 mA / cm². 2 The overpotential was 37.4 mV, slightly higher than the performance of the catalyst in Example 1 (27.5 mV), but it still exhibited good hydrogen evolution catalytic activity. This difference indicates that in the preparation method described in this invention, there is a certain correlation between the electrochemical performance of the catalyst and the raw material ratio. By adjusting the amount of precursor added, the catalytic activity can be effectively controlled within a certain range, further demonstrating the flexibility and adjustability of the method of this invention in optimizing material performance. Example 3

[0049] The only difference between this embodiment and Embodiment 1 is that: A surface-oxidized single-atom nano-alloy catalyst, specifically prepared by the following steps: (1) Weigh 100 mg of multi-walled carbon nanotubes and place them in a round-bottom flask. Add 50 mL of concentrated nitric acid (75%). Reflux the reaction at 110 °C in an oil bath for 6 hours. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water by centrifugation until the filtrate is neutral. Then freeze-dry for 10 hours to obtain hydroxylated multi-walled carbon nanotubes.

[0050] (2) Take 6 mg of the hydroxylated multi-walled carbon nanotubes prepared in step (1), 2 mg of ruthenium nitrate and 4 mg of copper chloride, and place them together in a 100 mL quartz reaction flask. Add 10 mL of methanol as solvent and sonicate at 180 W for 1.5 hours to form a uniform and stable black suspension.

[0051] (3) The above mixture was placed in the laser path and irradiated for 30 minutes using a neodymium-doped yttrium aluminum garnet pulsed laser with a pulse energy of 5 mJ, a repetition frequency of 10 Hz, and a pulse width of 5 ns. After 90 minutes of irradiation, the mixture was stirred and cooled for 15 minutes before a second laser irradiation. The laser irradiation process was repeated twice for a total of 180 minutes. Mechanical stirring was maintained throughout the reaction at a stirring rate of 500 rpm. After the reaction, the product was washed several times with ethanol and deionized water and freeze-dried for 10 h to obtain the surface-oxidized ruthenium copper single-atom nanoalloy catalyst (i.e., surface-oxidized single-atom nanoalloy catalyst) supported on hydroxylated carbon nanotubes.

[0052] A surface-oxidized single-atom nanoalloy catalyst includes a hydroxylated carbon nanotube support, bimetallic nanoalloy particles supported on the hydroxylated carbon nanotube support, wherein copper is dispersed in ruthenium nanoparticles in the form of single atoms in the bimetallic nanoalloy particles, the size of the bimetallic nanoalloy particles is 3-4 nm, and the surface of the bimetallic nanoalloy particles has an oxide layer; the loading of ruthenium is 5 wt%.

[0053] The oxide layer is approximately 0.5 nm thick and consists of amorphous CuO.

[0054] Application of a surface-oxidized single-atom nano-alloy catalyst in the hydrogen evolution reaction of water electrolysis.

[0055] A method for using a surface-oxidized single-atom nano-alloy catalyst, the preparation method of which uses the surface-oxidized single-atom nano-alloy catalyst as the working electrode is as follows: Weigh 4 mg of surface-oxidized single-atom nano-alloy catalyst powder and place it in a solution prepared by isopropanol, ethanol and Nafion in a ratio of 10:10:1 in 2 mL. Disperse the solution by ultrasonication for 60 minutes to obtain a uniformly dispersed catalyst ink. Divide the catalyst ink into four portions, each time taking 10 μL and uniformly drop-coating it onto the working electrode. Let it air dry at room temperature to obtain the final product.

[0056] The surface-oxidized single-atom nano-alloy catalyst of this embodiment exhibits excellent hydrogen evolution performance: at a current density of 10 mA / cm², 2 The overpotential was as low as 28.1 mV, and the Tafel slope was 23 mV / dec. Example 4

[0057] The only difference between this embodiment and Embodiment 1 is that: A surface-oxidized single-atom nano-alloy catalyst, specifically prepared by the following steps: (1) Weigh 300 mg of multi-walled carbon nanotubes and place them in a round-bottom flask. Add 200 mL of concentrated nitric acid (70%). Reflux the reaction at 150 °C in an oil bath for 10 hours. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water by centrifugation until the filtrate is neutral. Then freeze-dry for 16 hours to obtain hydroxylated multi-walled carbon nanotubes.

[0058] (2) Take 10 mg of the hydroxylated multi-walled carbon nanotubes prepared in step (1), 4 mg of ruthenium acetylacetone and 2 mg of copper nitrate, and place them together in an 80 mL quartz reaction flask. Add 20 mL of ethylene glycol as a solvent and sonicate at 150 W for 2 hours to form a uniform and stable black suspension.

[0059] (3) The above mixture was placed in the laser path and irradiated for 60 minutes using a neodymium-doped yttrium aluminum garnet pulsed laser with a pulse energy of 20 mJ, a repetition frequency of 30 Hz, and a pulse width of 10 ns. After 60 minutes of irradiation, the mixture was stirred and cooled for 12 minutes before a second laser irradiation was performed. The laser irradiation process was repeated twice for a total of 120 minutes. Mechanical stirring was maintained throughout the reaction at a stirring rate of 800 rpm. After the reaction, the product was washed several times with ethanol and deionized water and freeze-dried for 16 h to obtain the surface-oxidized ruthenium copper single-atom nanoalloy catalyst supported on hydroxylated carbon nanotubes (i.e., the surface-oxidized single-atom nanoalloy catalyst).

[0060] A surface-oxidized single-atom nanoalloy catalyst includes a hydroxylated carbon nanotube support, bimetallic nanoalloy particles supported on the hydroxylated carbon nanotube support, wherein copper is dispersed in ruthenium nanoparticles in the form of single atoms in the bimetallic nanoalloy particles, the size of the bimetallic nanoalloy particles is 3-4 nm, and the surface of the bimetallic nanoalloy particles has an oxide layer; the loading of ruthenium is 15 wt%.

[0061] The oxide layer is approximately 0.6 nm thick and consists of amorphous CuO.

[0062] Application of a surface-oxidized single-atom nano-alloy catalyst in the hydrogen evolution reaction of water electrolysis.

[0063] A method for using a surface-oxidized single-atom nano-alloy catalyst, the preparation method of which uses the surface-oxidized single-atom nano-alloy catalyst as the working electrode is as follows: 6 mg of surface-oxidized single-atom nano-alloy catalyst powder is weighed and placed in a solution prepared by isopropanol, ethanol and Nafion in a ratio of 10:10:1 in 2 mL, and ultrasonically dispersed for 45 minutes to obtain a uniformly dispersed catalyst ink; 6 μL of the catalyst ink is taken three times, each time and uniformly drop-coated onto the working electrode, and then dried at room temperature.

[0064] The surface-oxidized single-atom nano-alloy catalyst of this embodiment exhibits excellent hydrogen evolution performance: at a current density of 10 mA / cm², 2 The overpotential was as low as 30.8 mV, and the Tafel slope was 29 mV / dec.

[0065] Comparative Example 1

[0066] The only difference between this comparative example and Example 1 is that: The pulsed laser irradiation is performed once.

[0067] The loading of ruthenium metal is 3 wt%.

[0068] At a current density of 10 mA / cm 2 The overpotential is 45mV and the Tafel slope is 40 mV / dec.

[0069] Comparative Example 2

[0070] The only difference between this comparative example and Example 1 is that: The pulsed laser irradiation was performed three times.

[0071] The ruthenium metal loading is 18 wt%.

[0072] At a current density of 10 mA / cm 2 The overpotential is 52mV and the Tafel slope is 38 mV / dec.

[0073] In summary, the embodiments of the present invention provide a method for preparing surface-oxidized ruthenium copper single-atom nanoalloys on hydroxylated carbon nanotubes by liquid-phase pulsed laser irradiation. This method achieves a synergistic process of metal ion reduction, alloying, single-atom dispersion, and in-situ surface oxidation in one step under ambient temperature and pressure conditions using laser irradiation. The prepared alloy particles are uniform in size and distribution. The preparation process is green and efficient, requiring no high-temperature and high-pressure environment and not relying on surfactants or other auxiliary additives, falling within the category of soft chemical synthesis. The prepared catalyst exhibits excellent performance in the hydrogen evolution reaction of water electrolysis, showing broad application prospects in the field of energy conversion and storage.

[0074] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0075] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A surface-oxidized monatomic nanalloy catalyst, characterized by, The catalyst comprises a hydroxylated carbon nanotube carrier, bimetallic nano-alloy particles loaded on the hydroxylated carbon nanotube carrier, in the bimetallic nano-alloy particles, a non-noble metal element is dispersed in a noble metal nanoparticle in a monatomic form, the size of the bimetallic nano-alloy particles is 3-4 nm, and the bimetallic nano-alloy particles have an oxide layer on the surface; and the loading amount of the noble metal is 5-15 wt%.

2. The surface-oxidized monatomic nanalloy catalyst of claim 1, wherein, The thickness of the oxide layer is 0.3-0.6 nm.

3. The surface-oxidized monatomic nanalloy catalyst of claim 1, wherein, The non-noble metal element comprises copper, and the noble metal comprises ruthenium; the copper element is dispersed in a ruthenium metal lattice in a monatomic form.

4. The surface oxidation single-atom nano-alloy catalyst according to claim 1, characterized in that, The overpotential is below 40 mV at a current density of 10 mA / cm 2 The Tafel slope is less than 30 mV / dec.

5. A method for preparing a surface oxidation single-atom nano-alloy catalyst according to any one of claims 1 to 4, characterized in that, The catalyst comprises the following steps: dispersing a hydroxylated carbon nanotube, a ruthenium salt and a copper salt in a reducing solvent to form a uniform suspension, and irradiating the suspension with a pulsed laser under normal temperature and pressure in two stages, the pulsed energy of each stage is 5-20 mJ, the repetition frequency is 10-30 Hz, the pulse width is 5-10 ns, the irradiation time of each stage is 30-90 minutes, and the stirring cooling interval between the two stages is 10-15 minutes; after the reaction is completed, the solid product is washed and dried to obtain a surface-oxidized monatomic nano-alloy catalyst.

6. The production method according to claim 5, characterized by, The reducing solvent is ethanol, methanol or ethylene glycol.

7. The preparation method according to claim 5, characterized in that, The ruthenium salt is any one of ruthenium chloride, ruthenium nitrate or ruthenium acetylacetone; and the copper salt is any one of copper chloride, copper nitrate or copper acetate.

8. The preparation method according to claim 5, characterized in that, The catalyst comprises the following steps: S01, 100-300 mg of multi-walled carbon nanotubes are weighed and placed in a round-bottom flask, 50-200 mL of concentrated nitric acid is added, and the concentration of the concentrated nitric acid is greater than 68%; under the condition of an oil bath at 110-150 ℃, reflux reaction is carried out for 6-10 hours; after the reaction is completed, the temperature is cooled to room temperature, deionized water is repeatedly centrifuged to wash the filtrate to neutral, and then freeze-drying is carried out for 10-16 hours to obtain hydroxylated multi-walled carbon nanotubes; S02, 6-10 mg of the hydroxylated multi-walled carbon nanotubes prepared in S01, 2-4 mg of a ruthenium salt and 2-4 mg of a copper salt are taken and placed in a 50-100 mL quartz reaction bottle; 10-20 mL of a reducing solvent is added as a solvent, and ultrasonic treatment is carried out at a power of 120-180 W for not less than 1 hour and at a temperature of not higher than 40 ℃ to form a uniform and stable black suspension; S03, the suspension is placed in a laser light path, a neodymium yttrium aluminum garnet pulsed laser is used, and continuous irradiation is carried out under the conditions of a pulsed energy of 5-20 mJ, a repetition frequency of 10-30 Hz and a pulse width of 5-10 ns for 30-90 minutes; after each irradiation, stirring and cooling are carried out for 10-15 minutes, the second laser irradiation is carried out again, mechanical stirring is maintained during the whole reaction, and the stirring rate is 500-800 rpm; after the reaction is completed, the obtained product is repeatedly washed with ethanol and deionized water for several times and freeze-dried for 10-16 hours to obtain a surface-oxidized monatomic nano-alloy catalyst.

9. Application of the surface-oxidized monatomic nano-alloy catalyst according to any one of claims 1-4 in an electrolytic water hydrogen evolution reaction.

10. The use of a surface-oxidized monatomic nanoscale alloy catalyst according to any one of claims 1 to 4, characterized in that, The preparation method of the surface-oxidized single-atom nanoscale alloy catalyst as the working electrode is as follows: 3-6 mg of the surface-oxidized single-atom nanoscale alloy catalyst powder is taken and placed in a solution prepared according to a proportion of 10:10:1 of isopropanol, ethanol and Nafion, and ultrasonic dispersion is performed for 30-60 minutes to obtain a uniformly dispersed catalyst ink; 5-10 μL of the catalyst ink is uniformly dropped on the working electrode in three to four times, and the working electrode is dried at room temperature to obtain the working electrode.

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