Composite metal nanocatalyst, preparation method thereof and method for electrolytic water hydrogen evolution

Abstract

The application provides a composite metal nanocatalyst, a preparation method thereof and a water electrolysis hydrogen evolution method, the composite metal nanocatalyst comprising a columnar Sm-doped MoN carrier and metal nanoparticles loaded on the columnar Sm-doped MoN carrier; in the composite metal nanocatalyst, Sm is dispersed in the crystal lattice of MoN, and the composite metal nanocatalyst has a three-dimensional nanoflower structure composed of nanocolumns. Through atomic-level doping of Sm in the MoN carrier and d-f orbital hybridization, the electronic structure of the catalyst is accurately controlled, and the hydrogen evolution activity, reaction kinetics and long-term stability in harsh high-salt environments are improved; the composite metal nanocatalyst has good resistance to chloride ion poisoning while maintaining high activity, and exhibits good hydrogen evolution activity and stability in seawater electrolysis hydrogen production.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials and energy chemistry technology, and relates to a composite metal nanocatalyst and its preparation method and a method for hydrogen evolution by water electrolysis. Background Technology

[0002] Clean energy systems using green hydrogen as a carrier are a crucial pathway to achieving carbon neutrality. Hydrogen production through water electrolysis, driven by renewable energy, offers a feasible solution, but its large-scale application is limited by the increasing scarcity of freshwater resources. Directly utilizing the Earth's abundant seawater as an electrolyte provides a virtually unlimited resource base for hydrogen production, thus becoming an important direction for the development of water electrolysis technology. However, the practical application of seawater electrolysis faces significant challenges, especially for the cathode hydrogen evolution reaction (HER). High concentrations of chloride ions (Cl-) in seawater... - (Approximately 0.6 M) will occupy the active sites of the catalyst through strong adsorption, competing with the water adsorption / dissociation process, ultimately leading to a rapid decline in catalytic performance.

[0003] Regarding Cl - Conventional strategies for addressing poisoning, such as constructing physical protective layers or inhibiting chlorination reactions under strongly alkaline conditions, often come at the cost of sacrificing catalytic performance. A more fundamental solution lies in modulating the electronic structure of the catalyst, thereby simultaneously weakening the Cl-... - Adsorption and optimization of the binding energy of hydrogen intermediates. In this direction, the modulation of metal-support interaction (MSI) provides a powerful means: through charge transfer at the metal-support interface, the d-band center of the active metal and its adsorption properties can be effectively tuned.

[0004] Nickel (Ni) is widely used as a non-noble metal HER catalyst due to its low cost and natural abundance. However, pure Ni exhibits moderate intrinsic HER activity, characterized by undesirable hydrogen adsorption kinetics and a limited number of active sites. More importantly, in seawater or chloride-containing electrolytes, the Ni surface is highly susceptible to Cl- degradation. - Poisoning leads to a sharp decline in the HER activity of Ni, making bare Ni and even foamed nickel unsuitable for direct use in seawater electrolysis. To overcome these limitations, coupling Ni with a conductive and synergistic support has proven to be an effective strategy. Molybdenum nitride (MoN) possesses a noble metal-like electronic structure, excellent corrosion resistance, and high conductivity, making it an ideal support for constructing Ni-based heterostructure catalysts. However, the catalytic performance of conventional Ni / MoN catalysts remains unsatisfactory, especially in harsh seawater environments. The moderate electron transfer from Ni to MoN is insufficient to completely overcome Ni's influence on Cl-. -The strong adsorption affinity of the metal makes it difficult to meet application requirements in terms of activity and stability under actual operating conditions. Therefore, further enhancing the metal-support interaction in the Ni / MoN system to promote more significant electron redistribution is crucial for simultaneously achieving high HER activity and strong Cl-... - Tolerance is of great importance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite metal nanocatalyst, its preparation method, and a method for hydrogen evolution through water electrolysis. The present invention precisely controls the electronic structure of the catalyst by atomically doping Sm and df orbitals into a MoN support, thereby enhancing its hydrogen evolution activity, reaction kinetics, and long-term stability in harsh high-salt environments. The composite metal nanocatalyst maintains high activity while exhibiting excellent resistance to chloride ion poisoning, demonstrating good hydrogen evolution activity and stability in seawater electrolysis for hydrogen production.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a composite metal nanocatalyst comprising a columnar Sm-doped MoN support and metal nanoparticles supported on the columnar Sm-doped MoN support; wherein Sm is dispersed in the MoN lattice and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars.

[0007] Preferably, with the total mass of the columnar Sm-doped MoN support being 100%, the mass percentage of Sm is 0.2% to 2%.

[0008] Preferably, the diameter of the columnar Sm-doped MoN support is 200 nm to 5000 nm.

[0009] Preferably, the length of the columnar Sm-doped MoN support is 1 μm to 100 μm.

[0010] Preferably, the metal nanoparticles include any one or a combination of at least two of elemental nickel particles, elemental iron particles, elemental cobalt particles, elemental copper particles, or elemental zinc particles.

[0011] Preferably, the median particle size D50 of the metal nanoparticles is 2nm~20nm.

[0012] Preferably, the mass percentage of the metal nanoparticles is 10% to 50% based on the total mass of the composite metal nanocatalyst being 100%.

[0013] In a second aspect, the present invention provides a method for preparing the composite metal nanocatalyst as described in the first aspect, the method comprising the following steps: Soluble molybdenum salt, soluble samarium salt, and soluble transition metal salt are mixed with a solvent to form a precursor solution; The catalyst precursor was obtained by immersing the nickel foam substrate in the precursor solution and then reacting it on the surface of the nickel foam substrate through a hydrothermal reaction. The catalyst precursor was subjected to nitriding treatment to obtain the composite metal nanocatalyst.

[0014] Preferably, the soluble molybdenum salt includes ammonium molybdate.

[0015] Preferably, the soluble samarium salt includes samarium nitrate.

[0016] Preferably, the soluble transition metal salt includes any one or a combination of at least two of nickel nitrate, ferric nitrate, cobalt nitrate, copper nitrate, or zinc nitrate.

[0017] Preferably, the mass ratio of the soluble molybdenum salt, the soluble samarium salt, and the soluble transition metal salt is 1:(0.02~0.4):(0.1~0.5).

[0018] Preferably, the solvent includes water.

[0019] Preferably, the temperature of the hydrothermal reaction is 120℃~180℃.

[0020] Preferably, the hydrothermal reaction time is 4h to 24h.

[0021] Preferably, the atmosphere for the nitriding treatment comprises a mixture of ammonia and a protective gas.

[0022] Preferably, in the mixture of ammonia and protective gas, the volume percentage of ammonia is 2% to 20%.

[0023] Preferably, the flow rate of the mixture of ammonia and protective gas is 20 mL / min to 100 mL / min.

[0024] Preferably, the nitriding treatment temperature is 400℃~700℃.

[0025] Preferably, the heat treatment holding time is 1h to 4h.

[0026] Thirdly, the present invention provides a method for hydrogen evolution by electrolysis of water, wherein the method uses the composite metal nanocatalyst as described in the first aspect as the cathode hydrogen evolution catalyst, and water is decomposed to produce hydrogen under the drive of electric current.

[0027] Preferably, in the method, the current density initially reaches 10 mA / cm². 2The overpotential at that time is ≤60mV.

[0028] Preferably, in the method, at 10mA / cm 2 After 100 hours of constant current operation at the current density, the increase in overpotential is ≤20mV.

[0029] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention achieves atomic-level dispersed doping of Sm atoms in the MoN lattice. By hybridizing the 4f empty orbitals of Sm with the df orbitals of MoN, the electronic structure of the MoN support is precisely controlled. Sm doping enhances the interaction between the supported transition metal nanoparticles and the MoN support, and optimizes the electronic structure of the transition metal nanoparticles.

[0031] (2) The composite metal nanocatalyst described in this invention exhibits hydrogen evolution activity comparable to commercial Pt / C in 1 mol / L KOH solution, and surpasses commercial Pt / C at high current density. Moreover, the composite metal nanocatalyst has excellent resistance to NaCl poisoning. In 1 mol / L KOH solution prepared with simulated seawater containing different concentrations of NaCl, the overpotential remains almost unchanged, far exceeding that of commercial Pt / C and nickel foam. It can also operate stably for 100 hours without performance degradation, demonstrating excellent catalytic durability.

[0032] (3) This invention significantly improves the activity and stability of non-precious metal nanoparticles in the electrolysis of seawater for hydrogen evolution through Sm rare earth atomic-level doping and interface engineering strategies, and has important prospects for industrial application.

[0033] (4) The composite metal nanocatalyst of the present invention has an efficiency of 10 mA / cm². 2 The overpotential can reach up to 50mV, 500mA / cm 2 The overpotential can reach less than 200mV, and the Tafel slope can reach less than 44mV / dec. From a pure 1mol / L KOH solution to a 1mol / L KOH solution containing 4mol / L NaCl, the overpotential can reach less than 200mV, and the Tafel slope can reach less than 44mV / dec. 2 The overpotential increase can be controlled within 10mV, 10mA / cm 2 After 100 hours of operation, the potential increase can be up to 15mV. Attached Figure Description

[0034] Figure 1This is a SEM image of the composite metal nanocatalyst described in Example 1.

[0035] Figure 2 This is a TEM image of the composite metal nanocatalyst described in Example 1.

[0036] Figure 3 This is a HAADF-STEM image of the composite metal nanocatalyst described in Example 1.

[0037] Figure 4 This is the EDS image of the composite metal nanocatalyst described in Example 1.

[0038] Figure 5 This is the XRD pattern of the composite metal nanocatalyst described in Example 1.

[0039] Figure 6 This is a comparison of the X-ray photoelectron spectra of the composite metal nanocatalyst described in Example 1 and the catalyst prepared in Comparative Example 1.

[0040] Figure 7 The graphs show the polarization curves of the catalysts described in Example 1, Comparative Example 1, and Comparative Example 3, as well as nickel foam, in a 1 mol / L KOH solution.

[0041] Figure 8 This is a polarization curve of the composite metal nanocatalyst described in Example 1 in a 1 mol / L KOH solution prepared from simulated seawater containing different concentrations of NaCl.

[0042] Figure 9 This is a durability test diagram of the composite metal nanocatalyst described in Example 1 in a 1 mol / L KOH solution prepared in simulated seawater. Detailed Implementation

[0043] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0044] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0045] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0046] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0047] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined according to its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order in which they are written or in any order that does not conflict with the technology.

[0048] In a first aspect, the present invention provides a composite metal nanocatalyst in some specific embodiments, the composite metal nanocatalyst comprising a columnar Sm-doped MoN support and metal nanoparticles supported on the columnar Sm-doped MoN support; in the composite metal nanocatalyst, Sm is dispersed in the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars.

[0049] The composite metal nanocatalyst of the present invention has a three-dimensional nanoflower-like structure formed by the self-assembly of nanopillars, and the surface of the nanopillars has nanoscale roughness.

[0050] In the composite metal nanocatalyst described in this invention, Sm is in-situ doped into the MoN lattice in an atomically dispersed form. The 4f empty orbitals of Sm hybridize with the d-band of the MoN / metal nanoparticles, causing a downward shift in the Fermi level of the entire system, reducing charge transfer resistance, increasing the electrochemical active area, and thus synergistically improving HER performance. Furthermore, the strong covalent interaction between atomically doped Sm and N enhances lattice stability, inhibits chloride ion corrosion, and endows the catalyst with excellent salt resistance and long-term stability.

[0051] In some embodiments, with the total mass of the columnar Sm-doped MoN support being 100%, the mass percentage of Sm is 0.2% to 2%, for example: 0.2%, 0.5%, 1%, 1.5% or 2%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] In the preparation process of the composite metal nanocatalyst described in this invention, it is difficult to dope Sm into MoN. Therefore, Sm cannot be completely doped into the MoN lattice. However, most of the transition metal salts can form metal nanoparticles loaded on the support.

[0053] In some embodiments, the diameter of the columnar Sm-doped MoN support is 200 nm to 5000 nm, for example: 200 nm, 500 nm, 1000 nm, 2000 nm or 5000 nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] In some embodiments, the length of the columnar Sm-doped MoN support is 1 μm to 100 μm, for example: 1 μm, 5 μm, 10 μm, 50 μm or 100 μm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0055] In some embodiments, the metal nanoparticles include any one or a combination of at least two of elemental nickel particles, elemental iron particles, elemental cobalt particles, elemental copper particles, or elemental zinc particles. Typical but non-limiting examples include combinations of elemental nickel and elemental cobalt particles, combinations of elemental copper and elemental nickel particles, or combinations of elemental iron and elemental zinc particles.

[0056] In some embodiments, the median particle size D50 of the metal nanoparticles is 2nm to 20nm, for example: 2nm, 5nm, 8nm, 10nm, 15nm or 20nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] In some embodiments, with the total mass of the composite metal nanocatalyst being 100%, the mass percentage of the metal nanoparticles is 10% to 50%, for example: 10%, 20%, 30%, 40% or 50%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0058] Secondly, in some specific embodiments, the present invention provides a method for preparing the composite metal nanocatalyst as described in the first aspect, the method comprising the following steps: Soluble molybdenum salt, soluble samarium salt, and soluble transition metal salt are mixed with a solvent to form a precursor solution; The catalyst precursor was obtained by immersing the nickel foam substrate in the precursor solution and then reacting it on the surface of the nickel foam substrate through a hydrothermal reaction. The catalyst precursor was subjected to nitriding treatment to obtain the composite metal nanocatalyst.

[0059] The method of the present invention involves hydrothermally heating soluble samarium salt, molybdenum salt, and transition metal salt together to form a uniform precursor in situ on the surface of nickel foam; subsequently, a nitriding treatment is performed, in which the Mo precursor is nitrided into MoN, and Sm atoms are in situ doped into the MoN lattice in an atomically dispersed form during the nitriding process; at the same time, the transition metal precursor is reduced into metal nanoparticles and loaded onto the Sm-doped MoN support.

[0060] In some embodiments, the soluble molybdenum salt comprises ammonium molybdate.

[0061] In some embodiments, the soluble samarium salt includes samarium nitrate.

[0062] In some embodiments, the soluble transition metal salt includes any one or a combination of at least two of nickel nitrate, ferric nitrate, cobalt nitrate, copper nitrate, or zinc nitrate. Typical but non-limiting combinations include combinations of nickel nitrate and ferric nitrate, cobalt nitrate and ferric nitrate, or copper nitrate and nickel nitrate, etc.

[0063] In some embodiments, the mass ratio of the soluble molybdenum salt, the soluble samarium salt, and the soluble transition metal salt is 1:(0.02~0.4):(0.1~0.5), for example: 1:0.02:0.1, 1:0.05:0.2, 1:0.1:0.3, 1:0.2:0.4, or 1:0.4:0.5, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] In some embodiments, the solvent includes water.

[0065] In some embodiments, the temperature of the hydrothermal reaction is 120°C to 180°C, for example: 120°C, 130°C, 150°C, 160°C or 180°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0066] In some embodiments, the hydrothermal reaction time is 4h to 24h, for example: 4h, 8h, 12h, 16h or 24h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0067] In some embodiments, the atmosphere for the nitriding treatment comprises a mixture of ammonia and a protective gas.

[0068] In some embodiments, the volume percentage of ammonia in the mixture of ammonia and protective gas is 2% to 20%, for example: 2%, 5%, 10%, 15% or 20%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0069] In some embodiments, the flow rate of the mixture of ammonia and protective gas is 20 mL / min to 100 mL / min, for example: 20 mL / min, 40 mL / min, 60 mL / min, 80 mL / min or 100 mL / min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0070] In some embodiments, the nitriding temperature is 400°C to 700°C, for example: 400°C, 450°C, 500°C, 600°C or 700°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0071] In some embodiments, the holding time for the nitriding treatment is 1h to 4h, for example: 1h, 1.5h, 2h, 3h or 4h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0072] Thirdly, in some specific embodiments, the present invention provides a method for hydrogen evolution by electrolysis of water, wherein the method uses the composite metal nanocatalyst as described in the first aspect as the cathode hydrogen evolution catalyst, and water is decomposed to produce hydrogen under the drive of electric current.

[0073] The method for hydrogen production by electrolysis of water according to the present invention includes hydrogen production by electrolysis of seawater or hydrogen production by electrolysis of conventional water.

[0074] In some embodiments of the method, the current density initially reaches 10 mA / cm². 2 The overpotential at that time is ≤60mV.

[0075] In some embodiments of the method, at 10 mA / cm 2 After 100 hours of constant current operation at the current density, the increase in overpotential is ≤20mV.

[0076] Example 1 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental nickel nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 1%. The columnar Sm-doped MoN support has a diameter of 200 nm to 1000 nm and a length of 10 μm to 50 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 30%.

[0077] The composite metal nanocatalyst was prepared by the following method: Weigh 2g of ammonium molybdate, 0.37g of samarium nitrate, and 0.5g of nickel nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and nickel nitrate is 1:0.185:0.25), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 150°C for 6 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 500°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon gas (ammonia volume percentage of 5%) with a flow rate of 60 mL / min. The temperature was then maintained for 2 h for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0078] The SEM image of the composite metal nanocatalyst is shown below. Figure 1 As shown, the TEM image of the composite metal nanocatalyst is as follows. Figure 2 As shown, the HAADF-STEM image of the composite metal nanocatalyst is as follows. Figure 3 As shown, the EDS spectrum of the composite metal nanocatalyst is as follows: Figure 4 As shown, by Figures 1-4As can be seen, the composite metal nanocatalyst of the present invention has a three-dimensional nanoflower-like structure composed of nanopillars, and elemental Ni particles are distributed on the Sm-doped MoN support. The elemental distribution shows that N, Sm, Ni and Mo are uniformly distributed in the composite metal nanocatalyst.

[0079] The XRD pattern of the composite metal nanocatalyst is shown below. Figure 5 As shown, by Figure 5 It can be seen that the composite metal nanocatalyst of the present invention has obvious MoN and Ni elemental phases.

[0080] Example 2 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental nickel nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 0.2%. The columnar Sm-doped MoN support has a diameter of 600 nm to 2000 nm and a length of 5 μm to 30 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 10%.

[0081] The composite metal nanocatalyst was prepared by the following method: Weigh 2g of ammonium molybdate, 0.04g of samarium nitrate, and 0.2g of nickel nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and nickel nitrate is 1:0.02:0.1), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 180°C for 4 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 600°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon (ammonia volume percentage of 2%) with a flow rate of 60 mL / min. The temperature was then maintained for 2 h for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0082] Example 3 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental nickel nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 2%. The columnar Sm-doped MoN support has a diameter of 500 nm to 2000 nm and a length of 20 μm to 80 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 50%.

[0083] The composite metal nanocatalyst was prepared by the following method: Weigh 2g of ammonium molybdate, 0.74g of samarium nitrate, and 1g of nickel nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and nickel nitrate is 1:0.37:0.5), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 120°C for 24 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 450°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon gas (ammonia volume percentage of 10%) with a flow rate of 60 mL / min. The temperature was then maintained for 3 h for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0084] Example 4 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental nickel nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 1%. The columnar Sm-doped MoN support has a diameter of 200 nm to 1000 nm and a length of 10 μm to 50 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 40%.

[0085] The composite metal nanocatalyst was prepared by the following method: Weigh 2g of ammonium molybdate, 0.37g of samarium nitrate, and 0.8g of nickel nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and nickel nitrate is 1:0.185:0.4), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 150°C for 6 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 400°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon gas (ammonia volume percentage of 20%) with a flow rate of 60 mL / min. The temperature was then maintained for 2 hours for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0086] Example 5 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental cobalt nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 1%. The columnar Sm-doped MoN support has a diameter of 200 nm to 1000 nm and a length of 10 μm to 50 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 40%.

[0087] The composite metal nanocatalyst was prepared by the following method: Weigh out 2g of ammonium molybdate, 0.37g of samarium nitrate, and 0.8g of cobalt nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and cobalt nitrate is 1:0.185:0.4), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 150°C for 6 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 550°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon (ammonia volume percentage of 5%) at a flow rate of 60 mL / min. The temperature was then maintained for 2.5 h for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0088] Example 6 This embodiment provides a composite metal nanocatalyst, comprising a columnar Sm-doped MoN support and elemental iron nanoparticles with a median particle size D50 of 10 nm supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed within the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars. Based on the total mass of the columnar Sm-doped MoN support (100%), the mass percentage of Sm is 1%. The columnar Sm-doped MoN support has a diameter of 200 nm to 1000 nm and a length of 10 μm to 50 μm. Based on the total mass of the composite metal nanocatalyst (100%), the mass percentage of the metal nanoparticles is 40%.

[0089] The composite metal nanocatalyst was prepared by the following method: Weigh 2g of ammonium molybdate, 0.37g of samarium nitrate, and 0.8g of ferric nitrate (the mass ratio of ammonium molybdate, samarium nitrate, and ferric nitrate is 1:0.185:0.4), dissolve them together in 75mL of ultrapure deionized water, and sonicate for 10min to form a precursor solution; The precursor solution was transferred to a clean polytetrafluoroethylene liner and immersed in a piece of nickel foam substrate that had been pre-soaked in dilute hydrochloric acid for 20 minutes. The reactor was sealed and placed in an oven for hydrothermal reaction at 150°C for 6 hours. The reactor was repeatedly washed with anhydrous ethanol and deionized water to remove physically adsorbed impurity ions and loose deposits from the surface. The precursor was then dried in an oven at 60°C to obtain the catalyst precursor. The catalyst precursor was placed in a tube furnace and heated to 600°C at a rate of 10°C / min under a mixed atmosphere of ammonia / argon gas (ammonia volume percentage of 5%) with a flow rate of 60 mL / min. The temperature was then maintained for 1.5 h for nitriding treatment, ultimately generating the composite metal nanocatalyst on the surface of nickel foam.

[0090] Example 7 The only difference between this embodiment and Embodiment 1 is that the Sm doping amount in the columnar Sm-doped MoN support is 0.1%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0091] Example 8 The only difference between this embodiment and Embodiment 1 is that the Sm doping amount in the columnar Sm-doped MoN support is 3%, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0092] Example 9 The only difference between this embodiment and Example 1 is that the mass percentage of nickel nanoparticles in the composite metal nanocatalyst is controlled to be 5%, while the other conditions and parameters are exactly the same as in Example 1.

[0093] Example 10 The only difference between this embodiment and Example 1 is that the mass ratio of nickel nanoparticles in the composite metal nanocatalyst is controlled to be 60%, while other conditions and parameters are exactly the same as in Example 1.

[0094] Comparative Example 1 The only difference between this comparative example and Example 1 is that the MoN carrier is not doped with Sm; all other conditions and parameters are exactly the same as in Example 1.

[0095] Comparative Example 2 The only difference between this comparative example and Example 1 is that the Sm-doped MoN support does not contain Ni particles; all other conditions and parameters are exactly the same as in Example 1.

[0096] Comparative Example 3 This comparative example uses a commercially available Pt / C catalyst.

[0097] Performance testing: All electrochemical tests were performed on an electrochemical workstation (CHI 660E) connected to a standard three-electrode system. The prepared catalyst served as the working electrode, the graphite rod as the counter electrode, and the Hg / HgO electrode as the reference electrode. The electrolyte was a 1 mol / L KOH solution containing 0 mol / L, 0.6 mol / L, 2 mol / L, and 4 mol / L NaCl, respectively. Before the experiment, the electrolyte was bubbled with H2 for half an hour. All potentials were converted to the reversible hydrogen electrode (RHE) potential using the following formula: E(RHE) = E(Hg / HgO) + 0.098 + 0.059 × pH. The catalyst was activated for 1 hour using cyclic voltammetry (CV). The scan rate for recording linear sweep voltammetry (LSV) curves was 1 mV / s. Electrochemical impedance spectroscopy (EIS) was performed at frequencies ranging from 0.1 Hz to 10 Hz. 6 Hz. All polarization curves were corrected for 90% iR based on ohmic resistance measured by EIS. The double-layer capacitance of the catalyst (C0) dlThe performance was evaluated by CV tests at different scan rates (5–60 mV / s) within the non-Radar range (0.3–0.4 V relative to RHE), from pure 1 mol / L KOH solution to 1 mol / L KOH containing 4 mol / L NaCl, at 10 mA / cm². 2 The increase in overpotential is denoted as 10 mA / cm. 2 The increase in overpotential. The test results are shown in Table 1: Table 1 As can be seen from Table 1, based on Examples 1 to 10, the composite metal nanocatalyst of the present invention has a strength of 10 mA / cm². 2 The overpotential can reach less than 70mV, and after optimization, it can be controlled to less than 50mV, 500mA / cm 2 The overpotential can reach below 303 mV, and after optimization, it can be controlled below 200 mV. The Tafel slope can reach below 59.2 mV / dec, and after optimization, it can reach below 44 mV / dec. From pure 1 mol / L KOH solution to 1 mol / L KOH containing 4 mol / L NaCl, 10 mA / cm 2 The overpotential increase can be controlled within 18mV, and after optimization, it can be controlled within 10mV, 10mA / cm. 2 After 100 hours of operation, the increase in potential can reach less than 21mV, and after optimization, it can be controlled to within 15mV.

[0098] A comparison of Examples 1 and 7-8 shows that the Sm doping amount in the Sm-doped MoN support of the composite metal nanocatalyst of the present invention affects its performance. When the Sm doping amount in the Sm-doped MoN support is controlled at 0.2% to 2%, the composite metal nanocatalyst exhibits better performance. If the Sm doping amount in the Sm-doped MoN support is too low, the Sm's regulation of the electronic structure of the MoN support is insufficient, making it difficult to promote the interfacial interaction between the supported Ni particles and the MoN support, thus failing to improve catalytic activity. If the Sm doping amount in the Sm-doped MoN support is too high, the basic structure of the MoN support is destroyed, its support properties are altered, and its catalytic activity is reduced.

[0099] A comparison of Examples 1 and 9-10 shows that the mass percentage of metal nanoparticles in the composite metal nanocatalyst of the present invention affects its performance. When the mass percentage of metal nanoparticles is controlled between 10% and 50%, the composite metal nanocatalyst exhibits better performance. If the mass percentage of metal nanoparticles is too low, there will be less Ni active phase in the catalyst, resulting in insufficient catalytic sites and a decrease in catalytic activity. Conversely, if the mass percentage of metal nanoparticles is too high, the interfacial interaction between the accumulated Ni particles and the support will weaken, and the support will be unable to effectively regulate the electronic structure of the surface Ni particles, also leading to a decrease in catalytic activity.

[0100] Comparing Example 1 and Comparative Examples 1-2, it can be seen that in the composite metal nanocatalyst of the present invention, Sm is in-situ doped in the MoN lattice in an atomically dispersed form. The 4f empty orbitals of Sm hybridize with the d-band of the MoN / metal nanoparticles using df orbitals (Comparative Example 2 does not have nickel loading, therefore it has no activity), causing the Fermi level of the entire system to shift downward, reducing the charge transfer resistance, increasing the electrochemical active area, and thus synergistically improving HER performance. In addition, the strong covalent interaction between atomically doped Sm and N enhances lattice stability, inhibits chloride ion corrosion, and endows the catalyst with excellent salt resistance and long-term stability.

[0101] The X-ray photoelectron spectra of the composite metal nanocatalyst described in Example 1 and the catalyst prepared in Comparative Example 1 are shown in the figure below. Figure 6 As shown, by Figure 6 It can be seen that the valence state of Ni in the composite metal nanocatalyst described in this invention is different from that of the undoped Sm comparative sample (Ni / MoN), indicating that Sm doping effectively regulates the interaction between Ni and the MoN support, thereby regulating the electronic structure of Ni.

[0102] The polarization curves of the catalysts described in Example 1, Comparative Example 1, and Comparative Example 3, as well as the nickel foam, in 1 mol / L KOH solution are shown below. Figure 7 As shown, by Figure 7 It can be seen that the composite metal nanocatalyst described in this invention has excellent activity in catalyzing the hydrogen evolution reaction, and its performance is significantly better than that of undoped Sm catalysts, and in some indicators it surpasses commercially available Pt / C catalysts.

[0103] The polarization curves of the composite metal nanocatalyst described in Example 1 in 1 mol / L KOH solutions prepared from simulated seawater containing different concentrations of NaCl are shown below. Figure 8 As shown, by Figure 8 It can be seen that the catalytic activity of the composite metal nanocatalyst described in this invention is almost unaffected by NaCl in electrolytes containing different concentrations of NaCl, indicating that it has good resistance to sodium chloride poisoning.

[0104] The durability test results of the composite metal nanocatalyst described in Example 1 in a 1 mol / L KOH solution prepared using simulated seawater are shown in the figure below. Figure 9 As shown, by Figure 9 It can be seen that the composite metal nanocatalyst described in this invention shows almost no degradation within 100 hours, indicating that it has good durability.

[0105] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A composite metal nanocatalyst, characterized in that, The composite metal nanocatalyst comprises a columnar Sm-doped MoN support and metal nanoparticles supported on the columnar Sm-doped MoN support. In the composite metal nanocatalyst, Sm is dispersed in the MoN lattice, and the composite metal nanocatalyst exhibits a three-dimensional nanoflower-like structure composed of nanopillars.

2. The composite metal nanocatalyst as described in claim 1, characterized in that, With the total mass of the columnar Sm-doped MoN support being 100%, the mass percentage of Sm is 0.2% to 2%. Preferably, the diameter of the columnar Sm-doped MoN support is 200 nm to 5000 nm; Preferably, the length of the columnar Sm-doped MoN support is 1 μm to 100 μm.

3. The composite metal nanocatalyst as described in claim 1 or 2, characterized in that, The metal nanoparticles include any one or a combination of at least two of the following: elemental nickel particles, elemental iron particles, elemental cobalt particles, elemental copper particles, or elemental zinc particles. Preferably, the median particle size D50 of the metal nanoparticles is 2nm~20nm.

4. The composite metal nanocatalyst according to any one of claims 1-3, characterized in that, With the total mass of the composite metal nanocatalyst being 100%, the mass percentage of the metal nanoparticles is 10% to 50%.

5. A method for preparing the composite metal nanocatalyst according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: Soluble molybdenum salt, soluble samarium salt, and soluble transition metal salt are mixed with a solvent to form a precursor solution; The catalyst precursor was obtained by immersing the nickel foam substrate in the precursor solution and then reacting it on the surface of the nickel foam substrate through a hydrothermal reaction. The catalyst precursor was subjected to nitriding treatment to obtain the composite metal nanocatalyst.

6. The preparation method according to claim 5, characterized in that, The soluble molybdenum salt includes ammonium molybdate; Preferably, the soluble samarium salt includes samarium nitrate; Preferably, the soluble transition metal salt includes any one or a combination of at least two of nickel nitrate, ferric nitrate, cobalt nitrate, copper nitrate, or zinc nitrate; Preferably, the mass ratio of the soluble molybdenum salt, the soluble samarium salt, and the soluble transition metal salt is 1:(0.02~0.4):(0.1~0.5); Preferably, the solvent includes water.

7. The preparation method according to claim 5 or 6, characterized in that, The temperature of the hydrothermal reaction is 120℃~180℃; Preferably, the hydrothermal reaction time is 4h to 24h.

8. The preparation method according to any one of claims 5-7, characterized in that, The atmosphere for the nitriding treatment includes a mixture of ammonia and a protective gas; Preferably, in the mixture of ammonia and protective gas, the volume percentage of ammonia is 2% to 20%. Preferably, the flow rate of the mixture of ammonia and protective gas is 20 mL / min to 100 mL / min; Preferably, the nitriding treatment temperature is 400℃~700℃; Preferably, the heat treatment holding time is 1h to 4h.

9. A method for hydrogen evolution by electrolysis of water, characterized in that, The method uses the composite metal nanocatalyst as described in any one of claims 1-4 as the cathode hydrogen evolution catalyst, and water is decomposed to produce hydrogen under the drive of electric current.

10. The method as described in claim 9, characterized in that, In the method described above, the current density initially reaches 10 mA / cm². 2 The overpotential at that time is ≤60mV; Preferably, in the method, at 10mA / cm 2 After 100 hours of constant current operation at the current density, the increase in overpotential is ≤20mV.

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