Nickel-based noble metal multi-shell nanocage material as well as preparation method and application thereof

Abstract

The invention discloses a nickel-based noble metal multi-shell nanocage material and a preparation method and application thereof, and relates to the technical field of nano functional materials.According to the nickel-based noble metal multi-shell nanocage material and the preparation method thereof, nickel nanoparticles serve as a core material, and the complexing and growth rate of noble metal is regulated and controlled by controlling the using amount of ligands; the technology of precious metal multi-step precise feeding, step-by-step programmed heating and system residual ligand reuse is combined, and precise epitaxial growth of multiple precious metals on the surfaces of the nickel nanoparticles is achieved. And carrying out carbon carrier loading and inorganic acid selective etching to accurately remove a part of nickel matrix and reserve a complete noble metal shell layer, thereby finally preparing the nickel-based noble metal multi-shell nanocage material with a hollow structure.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically to a nickel-based noble metal multi-shell nanocage material, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, with its core advantages of zero carbon emissions and high energy density (140 MJ / kg, approximately three times that of petroleum and 4.5 times that of coal), has become a key direction for promoting the transformation of the energy structure from fossil fuels to green and clean energy, and is regarded as one of the disruptive technologies of the future energy revolution. The efficient conversion and utilization of hydrogen energy highly depends on electrocatalytic reactions (such as the hydrogen evolution reaction, oxygen reduction reaction, and hydrogen oxidation reaction). As the core component of the electrocatalytic system, the catalyst's catalytic activity, stability, and reaction selectivity directly determine the energy conversion efficiency, operational lifespan, and commercial feasibility of hydrogen energy conversion equipment.

[0003] Currently, noble metals such as ruthenium, platinum, and iridium, due to their excellent catalytic activity and electron transport properties, have become core catalytic materials in hydrogen-related electrocatalytic reactions and are widely used in various high-performance electrocatalytic systems. However, existing catalytic systems based on single-component noble metals face performance bottlenecks in complex electrocatalytic reactions (such as the multi-step charge-transfer oxygen reduction reaction) due to their "single type of active site and limited electronic structure regulation," making it difficult to achieve synergistic optimization of multiple reaction energy barriers. Furthermore, the chemical stability of a single component is insufficient, leading to easy catalytic activity decay. To overcome these limitations, constructing composite catalytic systems through the synergistic design of multiple noble metal components has become a key direction for improving electrocatalytic performance. Different noble metal components can precisely regulate the adsorption energy and catalytic kinetics of active sites through electronic coupling effects, while simultaneously enhancing structural stability through interfacial interactions between components, significantly breaking through the performance limits of single-component noble metals.

[0004] In multi-noble metal composite catalytic systems, core-shell structure-derived noble metal nanocages, with their high specific surface area, fully exposed active sites, and unique cavity structure, have become ideal support structures for achieving synergistic effects of multiple noble metals. These nanocages typically use transition metals as the structure-guiding matrix (to control the epitaxial growth orientation and morphology of the noble metal shells), and through subsequent processing, form multi-noble metal shell structures with specific catalytic functions. The composition, structural integrity, and interlayer synergistic effects of the multi-noble metal shells are the core determinants of catalytic performance. Compared to single-noble metal shells, multi-shell structures can achieve hierarchical layout of active sites by precisely designing the stacking order and interfacial bonding of different noble metals. Simultaneously, the interlayer electron transfer effect optimizes the rate-determining steps of the catalytic reaction, enhancing catalytic activity while strengthening structural stability through interlayer support, meeting the requirements for long-term operation of electrocatalytic devices.

[0005] However, existing technologies for preparing multi-noble metal shell nanocages still face bottlenecks related to core performance: on the one hand, the lack of precise control processes targeting the chemical properties of the multi-noble metal components easily leads to problems such as interdiffusion of components between multiple shells and poor thickness uniformity, resulting in weakened component synergistic effects and failure to achieve the expected optimization of catalytic activity; on the other hand, it is difficult to balance "shell structure integrity" and "active site exposure efficiency" during matrix control, often resulting in outer shell rupture and the shielding or corrosion of inner active sites, directly affecting catalytic stability; in addition, insufficient design of interfacial bonding strength between multiple shells makes them prone to interlayer delamination under cyclic conditions of electrocatalytic reactions, leading to rapid decay of catalytic performance. Furthermore, existing preparation systems require differentiated processes designed for the chemical properties of different noble metals (such as ruthenium, platinum, and iridium), making it difficult to achieve unified synthesis of various high-performance multi-noble metal nanocage materials, thus restricting the large-scale application of high-performance catalytic systems. Therefore, developing a process-controllable, structurally precise, and universally applicable method for preparing multi-noble metal shell nanocages to maximize the synergistic catalytic advantages of multi-components and overcome the performance bottlenecks of single-component catalysis has become a key challenge in promoting the commercialization of efficient hydrogen energy conversion technologies. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing nickel-based noble metal multi-shell nanocage materials, and the obtained nanocage materials exhibit good catalytic activity when used as catalysts in the oxygen reduction reaction (ORR).

[0007] The technical problem to be solved by the present invention is achieved by the following technical solution: One objective of this invention is to provide a method for preparing nickel-based noble metal multi-shell nanocage materials, comprising the following steps: (1) The first noble metal salt and the ligand are complexed to obtain a solution of the first noble metal-ligand complex; nickel nanoparticles are dispersed in the solvent to obtain a nickel nanoparticle dispersion. (2) After thoroughly mixing the nickel nanoparticle dispersion with the first noble metal-ligand complex solution, a solvothermal reaction was carried out to obtain the nickel@first noble metal nanoparticle dispersion. (3) Add a second noble metal salt to the nickel@first noble metal nanoparticle dispersion, and after the second noble metal and the residual ligand are fully complexed, carry out a solvothermal reaction to obtain a nickel@first noble metal@second noble metal nanoparticle dispersion. (4) Following the method in step (3), nickel@first noble metal@second noble metal@third noble metal...@Nth noble metal nanoparticle dispersions were prepared sequentially using the third noble metal salt...the Nth noble metal salt, centrifuged, washed, and dried to obtain nickel-based noble metal multi-shell nanoparticles; (5) The nickel-based noble metal multi-shell nanoparticles were thoroughly mixed with the carbon support to obtain carbon-supported nickel-based noble metal multi-shell nanoparticles. (6) Carbon-loaded nickel-based noble metal multi-shell nanoparticles were acid-etched, centrifuged, washed, and dried to obtain nickel-based noble metal multi-shell nanocage materials.

[0008] In this invention, washing, centrifuging, and drying a dispersion of nickel@first noble metal@second noble metal nanoparticles yields bilayer noble metal core-shell structured nanoparticles with nickel nanoparticles as the core, the first noble metal as the first shell, and the second noble metal as the second shell; washing, centrifuging, and drying a dispersion of nickel@first noble metal@second noble metal@third noble metal nanoparticles yields trilayer noble metal core-shell structured nanoparticles with nickel nanoparticles as the core, the first noble metal as the first shell, the second noble metal as the second shell, and the third noble metal as the third shell; and washing, centrifuging, and drying a dispersion of nickel@first noble metal@second noble metal@third noble metal...@Nth noble metal nanoparticles yields N-layer noble metal core-shell structured nanoparticles with nickel nanoparticles as the core, the first noble metal as the first shell, the second noble metal as the second shell, the third noble metal as the third shell,...@Nth noble metal as the Nth shell.

[0009] Furthermore, the ligand is selected from one or more organic amines such as hexadecylamine, octadecylamine, dodecylamine, and oleylamine.

[0010] Furthermore, the solvent is selected from one or more organic solvents such as diphenyl ether, ethylene glycol, and N,N-dimethylformamide. Ultrasonic dispersion is used to prepare the nickel nanoparticle dispersion to ensure that the nickel nanoparticles do not agglomerate.

[0011] Furthermore, the nickel nanoparticles have a particle size of 60~80 nm.

[0012] Furthermore, the first precious metal, the second precious metal, the third precious metal... the Nth precious metal are selected without repetition from one of ruthenium (Ru), palladium (Pd), iridium (Ir), platinum (Pt), rhodium (Rh) and osmium (Os).

[0013] Furthermore, the molar ratio of Ru, Pd, Ir, Pt, Rh, Os to the ligand in the first noble metal salt, the second noble metal salt, the third noble metal salt...the Nth noble metal salt is (0.005~0.006) : (0.005~0.006) : (0.007~0.008) : (0.002~0.003) : (0.003~0.004) : (0.005~0.006) : 1.

[0014] Furthermore, the complexation reaction is carried out at a temperature of 80~150℃ for a time of 30~120 min.

[0015] Furthermore, the solvothermal reaction is carried out under an inert atmosphere, preferably argon. Argon is used to replace the air in the reactor to prevent oxidation of nickel and the precious metal during the heating process.

[0016] Furthermore, the solvothermal reaction employs a stepwise programmed temperature rise method with a heating rate of 1~20℃ / min. The temperature is first raised to 175~185℃ and held for 1~3 h, then raised to 205~220℃ and held for 5~24 h. For different precious metals, corresponding stepwise programmed temperature rise parameters are set. For example, for Ru, the temperature is first raised to 180℃ and held for 2 h, then raised to 210℃ and held for 12 h; for Pd, the temperature is first raised to 180℃ and held for 2 h, then raised to 220℃ and held for 12 h; for Ir, the temperature is first raised to 180℃ and held for 2 h, then raised to 220℃ and held for 12 h; and for Pt, the temperature is first raised to 180℃ and held for 2 h, then raised to 205℃ and held for 12 h.

[0017] Furthermore, the molar ratio of nickel to Ru, Pd, Ir, Pt, Rh, and Os in the nickel-based noble metal multi-shell nanoparticles is 10 : (1~1.5) : (1~1.5) : (1.5~2) : (0.5~1) : (0.5~1) : (0.8~1.3).

[0018] Furthermore, the carbon support is at least one of carbon black and graphene, used to enhance the dispersibility and conductivity of the nanocage material, adapting to the charge transport requirements in electrocatalytic reactions.

[0019] In some specific embodiments, step (5) specifically includes: thoroughly mixing nickel-based noble metal multi-shell nanoparticles with a carbon support in a solvent, centrifuging, washing, and drying to obtain carbon-loaded nickel-based noble metal multi-shell nanoparticles. Preferably, the solvent is an ethanol / cyclohexane mixed solvent.

[0020] Furthermore, the acid etching is carried out under the action of an inorganic acid, preferably hydrochloric acid.

[0021] Furthermore, the acid etching is carried out in ethanol, which can dissolve inorganic acids and ensure uniform dispersion of carbon-loaded particles, thus avoiding uneven etching that could lead to shell cracking.

[0022] Furthermore, the acid etching temperature is 60~80℃, the time is 4~12 h, and the acid concentration is 2~4 mol / L, balancing the removal rate of the nickel substrate and the stability of the noble metal shell.

[0023] Furthermore, the centrifugation speed is 8000~12000 rpm to ensure the separation of pure core-shell structured nanoparticles or nanocage materials.

[0024] Furthermore, the washing process uses an ethanol / water mixed solvent, which can effectively remove unreacted ligands, residual noble metal salts and other impurities, thus avoiding affecting the catalytic performance of the nanocage material.

[0025] Furthermore, the drying process is vacuum drying at a temperature of 50-80°C to avoid the collapse of the core-shell structure or nanocage due to high temperatures.

[0026] The second objective of this invention is to provide a nickel-based noble metal multi-shell nanocage material prepared by the aforementioned method for preparing nickel-based noble metal multi-shell nanocage materials.

[0027] Furthermore, in the nickel-based noble metal multi-shell nanocage material, the molar ratio of noble metal to nickel is 1:(0.02~0.1), wherein the molar amount of noble metal is calculated as the total molar amount of the first noble metal salt and the second noble metal salt...the Nth noble metal salt. The residual Ni element is uniformly dispersed in the noble metal shell to form an alloy structure, which can regulate the electronic configuration of the noble metal through electronic interactions, enhancing the adsorption and desorption capacity of active sites for electrocatalytic reaction intermediates, and improving intrinsic catalytic activity.

[0028] Furthermore, the nickel-based noble metal multi-shell nanocage material exhibits high crystallinity, with no shell cracking or structural collapse, a diameter of 60-80 nm, a noble metal layer thickness of 1-4 nm, and tight interlayer interface bonding (verified by transmission electron microscopy-energy dispersive X-ray spectroscopy line scan, Ni element appears green, noble metal elements are sequentially coated in the preparation order, and the element signal boundaries are clear and free of impurities).

[0029] A third objective of this invention is to provide the application of the nickel-based noble metal multi-shell nanocage material as a catalyst in the ORR reaction.

[0030] The beneficial effects of this invention are: 1. This invention selects nickel nanoparticles with a size of 60~80 nm as the core material. By controlling the amount of ligands, the complexation and growth rate of noble metals are regulated. Combined with the process of "precise multi-step feeding of noble metals + step-by-step programmed heating + reuse of residual ligands in the system", the precise epitaxial growth of various noble metals on the surface of nickel nanoparticles is achieved. Then, by loading on a carbon support and selective etching with inorganic acid, part of the nickel matrix is ​​precisely removed while the complete noble metal shell is retained, and finally a nickel-based noble metal multi-shell nanocage material with a hollow structure is prepared.

[0031] 2. The nickel-based noble metal multi-shell nanocage material described in this invention exhibits excellent electrocatalytic performance when applied to the ORR reaction of a proton exchange membrane (PEM) fuel cell. Taking the nickel-based noble metal three-shell nanocage material H-Ni@Pd@Ru@Pt as an example, under the test conditions of 0.1 mol / L perchloric acid electrolyte and 1600 rpm, its half-wave potential can reach 0.93 V (vsRHE), which is higher than the half-wave potential (0.87 V) of the commercial JM platinum-carbon catalyst, showing a more prominent catalytic activity advantage.

[0032] 3. The preparation method of multi-shell nanoparticles and multi-shell nanocage materials provided by the present invention can be adapted to the preparation of multi-shell materials of noble metals such as ruthenium, platinum, iridium and palladium. The process parameters are controllable, the method is universal, and it is conducive to large-scale production. It provides high-performance material support for electrocatalytic reactions such as oxygen reduction and hydrogen evolution in the field of hydrogen energy conversion. Attached Figure Description

[0033] Figure 1 Transmission electron microscopy (TEM) image of the nickel nanoparticles prepared in this invention; Figure 2 Transmission electron microscopy (TEM) images of H-Ni@Ru@Pt nanocages (left, scale bar 100 nm), H-Ni@Pd@Ru@Pt nanocages (middle, scale bar 200 nm), and H-Ni@Pd@Ru@Ir nanocages (right, scale bar 200 nm) prepared in Examples 1, 2, and 3 of this invention. Figure 3 The image shows the elemental distribution of Ni@Ru@Pt nanoparticles prepared in Example 1 of this invention (Ni (green), Ru (red), Pt (blue), scale bar 50 nm) and the results of energy dispersive spectroscopy (EDS) line scan analysis. Figure 4 The image shows the elemental distribution of Ni@Pd@Ru@Pt nanoparticles prepared in Example 2 of this invention (Ni (green), Pd (cyan), Ru (red), Pt (blue), scale bar 50 nm) and the results of EDS line scan analysis. Figure 5 The image shows the elemental distribution of the H-Ni@Pd@Ru@Pt nanocages prepared in Example 2 of this invention (Ni (green), Pd (cyan), Ru (red), Pt (blue), scale bar 50 nm) and the results of EDS line scan analysis. Figure 6 The elemental distribution images (Ni (green), Pd (cyan), Ru (red), Ir (orange), scale bar 50 nm) and EDS line scan analysis results of the Ni@Pd@Ru@Ir nanoparticles prepared in Example 3 of this invention are shown. Figure 7The image shows the elemental distribution of the H-Ni@Pd@Ru@Ir nanocages prepared in Example 3 of this invention (Ni (green), Pd (cyan), Ru (red), Ir (orange), scale bar 50 nm) and the results of EDS line scan analysis. Figure 8 Linear sweep voltammetric curves of the H-Ni@Ru@Pt nanocages prepared in Example 1 and the H-Ni@Pd@Ru@Pt nanocages prepared in Example 2, compared with the commercial JM platinum-carbon catalyst of Comparative Example 1 and the H-Ni@Pt nanocages prepared in Comparative Example 2, in the ORR reaction (test conditions: 0.1 mol / L perchloric acid electrolyte, rotation speed 1600 rpm). Detailed Implementation

[0034] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.

[0035] The preparation methods of nickel nanoparticles in the embodiments and comparative examples of this invention are as follows: 1.2 g of polyethyleneimine (molecular weight 10000) and 0.45 g of nickel acetylacetonate were added to 22 mL of N,N-dimethylformamide and sonicated to form a homogeneous solution. The solution was then transferred to a polytetrafluoroethylene-lined reactor, and argon gas was used to purge the air from the reactor. The reactor was heated to 200 °C and reacted for 24 h. After the reaction was completed, the reaction solution was cooled to room temperature, and the black solid was collected. The solid was centrifuged three times alternately with ethanol and acetone (10000 rpm / 2 min). 5 mL of ethanol and 1 mL of n-butylamine were added and sonicated for 10 min. The solid was then centrifuged three times alternately with ethanol and acetone (10000 rpm / 2 min) and dried under vacuum at 60 °C for 6 h to obtain nickel nanoparticles. Figure 1 This is a transmission electron microscope (TEM) image of nickel nanoparticles. From... Figure 1 It can be seen that the nickel nanoparticles are hexagonal prisms with good dispersibility and no obvious agglomeration. The particle size distribution is in the range of 60~80 nm, which meets the requirements of core material dispersibility and size for core-shell structure preparation. They can be used as a stable core matrix for subsequent epitaxial growth of noble metals.

[0036] Example 1: Preparation of H-Ni@Ru@Pt nanocages Step 1: Add 0.037 mmol of ruthenium acetylacetone to 1.6 g of hexadecylamine, heat to 120℃ for 2 h to form a complex solution, and then ultrasonically disperse 18 mg of nickel nanoparticles in 10 mL of diphenyl ether to obtain a nickel nanoparticle dispersion.

[0037] Step 2: The nickel nanoparticle dispersion and the ruthenium-hexadecylamine complex solution were ultrasonically mixed for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 210℃ and held for 12 h. The mixture was then cooled to room temperature to obtain the Ni@Ru nanoparticle dispersion.

[0038] Step 3: Add 0.0193 mmol of chloroplatinic acid to the Ni@Ru nanoparticle dispersion, sonicate for 10 min, and heat to 120℃ for complexation reaction for 2 h; purge the air with argon gas, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 205℃ and hold for 12 h, cool to room temperature, centrifuge and wash 3 times (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1), and vacuum dry at 60℃ for 4 h to obtain Ni@Ru@Pt nanoparticles.

[0039] Step 4: Take 20 mg of Ni@Ru@Pt nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Ru@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; ultrasonically mix the Ni@Ru@Pt nanoparticle dispersion and the conductive carbon dispersion for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Ru@Pt nanoparticles.

[0040] Step 5: Disperse 30 mg of carbon-loaded Ni@Ru@Pt nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and dry under vacuum at 60 °C for 6 h to obtain H-Ni@Ru@Pt nanocages.

[0041] Example 2: Preparation of H-Ni@Pd@Ru@Pt nanocages Step 1: Add 0.036 mmol of ammonium tetrachloropalladate to 1.6 g of hexadecylamine, heat to 120℃ for 2 h to form a complex solution of palladium-hexadecylamine; disperse 18 mg of nickel nanoparticles in 10 mL of diphenyl ether by ultrasonication to obtain a nickel nanoparticle dispersion.

[0042] Step 2: The nickel nanoparticle dispersion and the palladium-hexadecylamine complex solution were ultrasonically mixed for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 220℃ and held for 12 h. The mixture was then cooled to room temperature to obtain the Ni@Pd nanoparticle dispersion.

[0043] Step 3: Add 0.037 mmol of ruthenium acetylacetone to the Ni@Pd nanoparticle dispersion, sonicate for 10 min, heat to 120℃ for complexation reaction for 2 h; purge with argon to replace the air, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 210℃ and hold for 12 h, cool to room temperature to obtain Ni@Pd@Ru nanoparticle dispersion.

[0044] Step 4: Add 0.0193 mmol of chloroplatinic acid to the Ni@Pd@Ru nanoparticle dispersion, sonicate for 10 min, and heat to 120℃ for complexation reaction for 2 h; purge the air with argon gas, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 205℃ and hold for 12 h, cool to room temperature, centrifuge and wash 3 times (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1), and vacuum dry at 60℃ for 4 h to obtain Ni@Pd@Ru@Pt nanoparticles.

[0045] Step 5: Take 20 mg of Ni@Pd@Ru@Pt nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Ru@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; add the Ni@Ru@Pt nanoparticle dispersion dropwise to the conductive carbon dispersion, ultrasonically mix for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Pd@Ru@Pt nanoparticles.

[0046] Step 6: Disperse 30 mg of carbon-loaded Ni@Pd@Ru@Pt nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and vacuum dry at 60 °C for 6 h to obtain H-Ni@Pd@Ru@Pt nanocages.

[0047] Example 3: Preparation of H-Ni@Pd@Ru@Ir nanocages Step 1: Add 0.036 mmol of ammonium tetrachloropalladate to 1.6 g of hexadecylamine, heat to 120℃ for 2 h to form a complex solution of palladium-hexadecylamine; disperse 18 mg of nickel nanoparticles in 10 mL of diphenyl ether by ultrasonication to obtain a nickel nanoparticle dispersion.

[0048] Step 2: The nickel nanoparticle dispersion and the palladium-hexadecylamine complex solution were ultrasonically mixed for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 220℃ and held for 12 h. The mixture was then cooled to room temperature to obtain the Ni@Pd nanoparticle dispersion.

[0049] Step 3: Add 0.037 mmol of ruthenium acetylacetone to the Ni@Pd nanoparticle dispersion, sonicate for 10 min, heat to 120℃ for complexation reaction for 2 h; purge with argon to replace the air, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 210℃ and hold for 12 h, cool to room temperature to obtain Ni@Pd@Ru nanoparticle dispersion.

[0050] Step 4: Add 0.0512 mmol of chloroiridium acid to the Ni@Pd@Ru nanoparticle dispersion, sonicate for 10 min, and heat to 120℃ for complexation reaction for 2 h; purge the air with argon gas, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 220℃ and hold for 12 h, cool to room temperature, centrifuge and wash 3 times (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1), and vacuum dry at 60℃ for 4 h to obtain Ni@Pd@Ru@Ir nanoparticles.

[0051] Step 5: Take 20 mg of Ni@Pd@Ru@Ir nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Ru@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; add the Ni@Ru@Pt nanoparticle dispersion dropwise to the conductive carbon dispersion, ultrasonically mix for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Pd@Ru@Ir nanoparticles.

[0052] Step 6: Disperse 30 mg of carbon-loaded Ni@Pd@Ru@Ir nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and vacuum dry at 60 °C for 6 h to obtain H-Ni@Pd@Ru@Ir nanocages.

[0053] Example 4: Preparation of H-Ni@Pd@Ir nanocages Step 1: Add 0.036 mmol of ammonium tetrachloropalladium to 1.6 g of hexadecylamine, heat to 120℃ and react for 2 h to obtain a palladium-hexadecylamine complex solution; disperse 18 mg of nickel nanoparticles ultrasonically in 10 mL of diphenyl ether to obtain a nickel nanoparticle dispersion.

[0054] Step 2: The nickel nanoparticle dispersion and the palladium-hexadecylamine complex solution were ultrasonically mixed for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 220℃ and held for 12 h. The mixture was then cooled to room temperature to obtain the Ni@Pd nanoparticle dispersion.

[0055] Step 3: Add 0.0512 mmol of chloroiridium acid to the Ni@Pd nanoparticle dispersion, sonicate for 10 min, and heat to 120℃ for complexation reaction for 2 h; purge with argon gas to replace the air, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 220℃ and hold for 12 h, cool to room temperature, centrifuge and wash 3 times (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1), and vacuum dry at 60℃ for 4 h to obtain Ni@Pd@Ir nanoparticles.

[0056] Step 4: Take 20 mg of Ni@Pd@Ir nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Ru@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; ultrasonically mix the Ni@Ru@Pt nanoparticle dispersion and the conductive carbon dispersion for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Pd@Ir nanoparticles.

[0057] Step 5: Disperse 30 mg of carbon-loaded Ni@Pd@Ir nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and vacuum dry at 60 °C for 6 h to obtain H-Ni@Pd@Ir nanocages.

[0058] Example 5: Preparation of H-Ni@Ru@Ir nanocages Step 1: Add 0.037 mmol of ruthenium acetylacetone to 1.6 g of hexadecylamine, heat to 120℃ for 2 h to form a complex solution, and then ultrasonically disperse 18 mg of nickel nanoparticles in 10 mL of diphenyl ether to obtain a nickel nanoparticle dispersion.

[0059] Step 2: The nickel nanoparticle dispersion and the ruthenium-hexadecylamine complex solution were ultrasonically mixed for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 210℃ and held for 12 h. The mixture was then cooled to room temperature to obtain the Ni@Ru nanoparticle dispersion.

[0060] Step 3: Add 0.0512 mmol of chloroiridium acid to the Ni@Pd nanoparticle dispersion, sonicate for 10 min, and heat to 120℃ for complexation reaction for 2 h; purge with argon gas to replace the air, heat to 180℃ at a rate of 3℃ / min and hold for 2 h, then heat to 220℃ and hold for 12 h, cool to room temperature, centrifuge and wash 3 times (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1), and vacuum dry at 60℃ for 4 h to obtain Ni@Ru@Ir nanoparticles.

[0061] Step 4: Take 20 mg of Ni@Ru@Ir nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Ru@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; ultrasonically mix the Ni@Ru@Pt nanoparticle dispersion and the conductive carbon dispersion for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Ru@Ir nanoparticles.

[0062] Step 5: Disperse 30 mg of carbon-loaded Ni@Pd@Ir nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and vacuum dry at 60 °C for 6 h to obtain H-Ni@Ru@Ir nanocages.

[0063] Comparative Example 1: Commercial Platinum-Carbon Catalyst The commercially available platinum-carbon catalyst, specifically Johnson Matthey (JM) platinum-carbon catalyst, was purchased from Suzhou Shengernuo Technology Co., Ltd.

[0064] Comparative Example 2: Preparation of H-Ni@Pt Nanocages Step 1: Add 0.0193 mmol chloroplatinic acid to 1.6 g hexadecylamine and heat to 120℃ for 2 h to obtain a platinum-hexadecylamine complex solution; disperse 18 mg nickel nanoparticles ultrasonically in 10 mL diphenyl ether to obtain a nickel nanoparticle dispersion.

[0065] Step 2: The nickel nanoparticle dispersion was ultrasonically mixed with the platinum-hexadecylamine complex solution for 60 min. Argon gas was introduced to replace the air. The temperature was first increased to 180℃ at a rate of 3℃ / min and held for 2 h, then increased to 205℃ and held for 12 h. After cooling to room temperature, the nanoparticles were washed three times by centrifugation (10000 rpm / 2 min) with a mixed solvent of ethanol / cyclohexane (volume ratio of ethanol to cyclohexane is 1:1). The nanoparticles were then vacuum dried at 60℃ for 4 h to obtain Ni@Pt nanoparticles.

[0066] Step 3: Take 20 mg of Ni@Pt nanoparticles and ultrasonically disperse them in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain Ni@Pt nanoparticle dispersion; take 10 mg of conductive carbon (Vulcan XC-72R) and ultrasonically disperse it in 10 mL of ethanol / cyclohexane mixed solvent (ethanol to cyclohexane volume ratio of 1:1) to obtain conductive carbon dispersion; ultrasonically mix the Ni@Pt nanoparticle dispersion and the conductive carbon dispersion for 30 min, centrifuge (8000 rpm / 2 min), discard the supernatant, and vacuum dry at 60℃ for 4 h to obtain carbon-supported Ni@Ru@Pt nanoparticles.

[0067] Step 4: Disperse 30 mg of carbon-loaded Ni@Pt nanoparticles in 9 mL of ethanol, add 0.5 mL of hydrochloric acid (3 mol / L) and stir for 10 min, then heat to 70 °C and stir for 10 h. Wash three times with ethanol by centrifugation (8000 rpm / 2 min), and vacuum dry at 60 °C for 6 h to obtain H-Ni@Pt nanocages.

[0068] Figure 2 Transmission electron microscopy (TEM) images of H-Ni@Ru@Pt nanocages (left, scale bar 100 nm), H-Ni@Pd@Ru@Pt nanocages (middle, scale bar 200 nm), and H-Ni@Pd@Ru@Ir nanocages (right, scale bar 200 nm) prepared in Examples 1, 2, and 3 of this invention. Figure 2 It can be seen that after acid etching, the core-shell structure forms a complete hollow cage-like morphology without cage wall cracking or structural collapse, with a diameter of 60~80 nm, which verifies the selectivity and controllability of the acid etching process described in this invention.

[0069] Figure 3 The image shows the elemental distribution of Ni@Ru@Pt nanoparticles prepared in Example 1 of this invention (distribution of Ni (green), Ru (red), and Pt (blue), scale bar 50 nm) and the results of EDS line scan analysis. Figure 3 As can be seen, the green area clearly corresponds to the nickel core, and its surface is tightly covered with a red Ru shell and a blue Pt shell in a radial direction. The shell thickness is uniform (about 1~4nm). Elemental linear scanning analysis of individual particles shows that the elemental characteristic signals of the two noble metals, Ru and Pt, are detected in an orderly manner in the order of Ru→Pt. This strongly confirms that the two noble metals have been successfully and accurately epitaxially grown layer by layer on the surface of the nickel core. The core-shell structure is regular and complete, and the interfaces of each layer are tightly bonded.

[0070] Figure 4 The image shows the elemental distribution (Ni (green), Pd (cyan), Ru (red), Pt (blue), scale bar 50 nm) and EDS line scan analysis results of the Ni@Pd@Ru@Pt nanoparticles prepared in Example 2 of this invention. Figure 4 As can be seen, the green area is a nickel core, which is successively covered by a cyan Pd shell, a red Ru shell, and a blue Pt shell. The shell thickness is uniform (about 1~4 nm). Elemental linear scanning analysis of individual particles shows that the elemental characteristic signals of the three noble metals, Pd, Ru, and Pt, are detected in an orderly manner in the order of Pd→Ru→Pt. This strongly confirms that the three noble metals have been successfully and accurately epitaxially grown layer by layer on the surface of the nickel core. The core-shell structure is regular and complete, and the interfaces of each layer are tightly bonded.

[0071] Figure 5 The image shows the elemental distribution (Ni (green), Pd (cyan), Ru (red), Pt (blue), scale bar 50 nm) and EDS line scan analysis results of the H-Ni@Pd@Ru@Pt nanocages prepared in Example 2 of this invention. Figure 5It can be seen that the green (Ni) signal is uniformly dispersed in the nanocage shell, and its surface is tightly covered with a cyan Pd shell, a red Ru shell, and a blue Pt shell in a radial sequence. The thickness of the noble metal shell is uniform and the thickness range is precise (about 1~4 nm). Elemental linear scanning analysis of the nanocage shows that the Ni element signal is continuously detected in the shell scanning path, while the elemental characteristic signals of the three noble metals, Pd, Ru, and Pt, appear in an orderly manner in the order of Pd→Ru→Pt. This strongly confirms that after acid etching, the three noble metals still maintain the precise, layer-by-layer epitaxial growth characteristics on the nickel-based surface. The nanocage structure is regular and complete, and the interfaces of each layer are tightly bonded. The etching process did not destroy the orderly distribution of elements and the stability of the hierarchical structure.

[0072] Figure 6 The image shows the elemental distribution of Ni@Pd@Ru@Ir nanoparticles prepared in Example 3 of this invention (distribution of Ni (green), Pd (cyan), Ru (red), and Ir (orange, scale bar 50 nm) and the results of EDS line scan analysis. Figure 6 As can be seen, the green area is a nickel core, which is successively covered by a cyan Pd shell, a red Ru shell, and an orange Ir shell. The shell thickness is uniform (about 1~4 nm). Elemental linear scanning analysis of individual particles shows that the elemental characteristic signals of the three noble metals, Pd, Ru, and Ir, are detected in an orderly manner in the order of Pd→Ru→Ir. This strongly confirms that the three noble metals have been successfully and accurately epitaxially grown layer by layer on the surface of the nickel core. The core-shell structure is regular and complete, and the interfaces of each layer are tightly bonded.

[0073] Figure 7 The image shows the elemental distribution (Ni (green), Pd (cyan), Ru (red), Ir (orange)), scale bar 50 nm) of the H-Ni@Pd@Ru@Ir nanocages prepared in Example 3 of this invention, along with EDS line scan analysis results. Figure 7 It can be seen that the green (Ni) signal is uniformly dispersed in the nanocage shell, and its surface is tightly covered with a cyan Pd shell, a red Ru shell, and an orange Ir shell in a radial sequence. The thickness of the noble metal shell is uniform and the thickness range is precise (about 1~4 nm). Elemental linear scanning analysis of the nanocage shows that the Ni element signal is continuously detected in the shell scanning path, while the elemental characteristic signals of the three noble metals, Pd, Ru, and Ir, appear in an orderly manner in the order of Pd→Ru→Ir. This strongly confirms that after acid etching, the three noble metals still maintain the precise, layer-by-layer epitaxial growth characteristics on the nickel-based surface. The nanocage structure is regular and complete, and the interfaces of each layer are tightly bonded. The etching process did not destroy the orderly distribution of elements and the stability of the hierarchical structure.

[0074] Figure 8Linear sweep voltammetric curves of the H-Ni@Ru@Pt nanocages prepared in Example 1 and Example 2 of this invention, compared with the commercial JM platinum-carbon catalyst of Comparative Example 1 and the H-Ni@Pt nanocages prepared in Comparative Example 2, in the ORR reaction (test conditions: 0.1 mol / L perchloric acid electrolyte, rotation speed 1600 rpm). Figure 8 It is known that the half-wave potential of H-Ni@Ru@Pt nanocages is 0.91 V (vs RHE), and the half-wave potential of H-Ni@Pd@Ru@Pt nanocages is 0.93 V (vs RHE), while the half-wave potential of commercial JM platinum-carbon catalysts is 0.87 V (vs RHE), and the half-wave potential of H-Ni@Pt nanocages is 0.83 V (vs RHE). This fully demonstrates that the noble metal multi-shell nanocage material designed in this invention has significantly better intrinsic catalytic activity than traditional single-component catalysts and commercial catalytic systems in the field of ORR electrocatalysis. It effectively breaks through the performance limit of existing ORR electrocatalytic reactions and provides key technical references and theoretical support for the structural design, active site regulation and stability optimization of high-performance catalysts in multi-step electrocatalysis processes.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nickel-based noble metal multi-shell nanocage material, characterized in that, Includes the following steps: (1) The first noble metal salt is complexed with the ligand to obtain a solution of the first noble metal-ligand complex; nickel nanoparticles are dispersed in the solvent to obtain a nickel nanoparticle dispersion. (2) After thoroughly mixing the nickel nanoparticle dispersion with the first noble metal-ligand complex solution, a solvothermal reaction was carried out to obtain the nickel@first noble metal nanoparticle dispersion. (3) Add a second noble metal salt to the nickel@first noble metal nanoparticle dispersion, and after the second noble metal and the residual ligand are fully complexed, carry out a solvothermal reaction to obtain a nickel@first noble metal@second noble metal nanoparticle dispersion. (4) Following the method in step (3), nickel@first noble metal@second noble metal@third noble metal...@Nth noble metal nanoparticle dispersions were prepared sequentially using the third noble metal salt...the Nth noble metal salt, centrifuged, washed, and dried to obtain nickel-based noble metal multi-shell nanoparticles; (5) The nickel-based noble metal multi-shell nanoparticles were thoroughly mixed with the carbon support to obtain carbon-supported nickel-based noble metal multi-shell nanoparticles. (6) Carbon-supported nickel-based noble metal multi-shell nanoparticles were acid-etched, centrifuged, washed, and dried to obtain nickel-based noble metal multi-shell nanocage materials.

2. The preparation method according to claim 1, characterized in that: The ligand is selected from one or more of hexadecylamine, octadecylamine, dodecylamine, and oleylamine; Preferably, the solvent is selected from one or more of diphenyl ether, ethylene glycol, and N,N-dimethylformamide; Preferably, the nickel nanoparticles have a particle size of 60-80 nm; Preferably, the carbon support is at least one of carbon black and graphene; Preferably, the complexation reaction is carried out at a temperature of 80~150℃ for a time of 30~120 min; Preferably, the solvothermal reaction is carried out under an inert atmosphere.

3. The preparation method according to claim 1, characterized in that: The first precious metal, the second precious metal, the third precious metal... the Nth precious metal are selected without repetition from one of Ru, Pd, Ir, Pt, Rh and Os.

4. The preparation method according to claim 1, characterized in that: The molar ratios of Ru, Pd, Ir, Pt, Rh, and Os to the ligands in the first, second, third, ..., Nth noble metal salts are (0.005~0.006):(0.005~0.006):(0.007~0.008):(0.002~0.003):(0.003~0.004):(0.005~0.006):

1.

5. The preparation method according to claim 1, characterized in that: The solvothermal reaction adopts a stepwise programmed heating method with a heating rate of 1~20℃ / min. First, the temperature is raised to 175~185℃ and held for 1~3 h, and then raised to 205~220℃ and held for 5~24 h.

6. The preparation method according to claim 1, characterized in that: The molar ratio of Ni to Ru, Pd, Ir, Pt, Rh, and Os in the nickel-based noble metal multi-shell nanoparticles is 10 : (1~1.5) : (1~1.5) : (1.5~2) : (0.5~1) : (0.5~1) : (0.8~1.3).

7. The preparation method according to claim 1, characterized in that: The acid etching is performed under the action of inorganic acid; Preferably, the acid etching temperature is 60~80℃, the time is 4~12 h, and the acid concentration is 2~4 mol / L.

8. Nickel-based noble metal multi-shell nanocage material prepared by the preparation method according to any one of claims 1 to 7.

9. The nickel-based noble metal multi-shell nanocage material according to claim 8, characterized in that: The molar ratio of noble metal to nickel in the nickel-based noble metal multi-shell nanocage material is 1: (0.02~0.1), wherein the molar amount of noble metal is calculated as the total molar amount of the first noble metal salt and the second noble metal salt... the Nth noble metal salt; Preferably, the nickel-based noble metal multi-shell nanocage material is highly crystalline, without shell cracking or structural collapse, has a diameter of 60-80 nm, a noble metal layer thickness of 1-4 nm, and a tight interlayer interface.

10. The application of the nickel-based noble metal multi-shell nanocage material as described in claim 8 or 9 as a catalyst in the ORR reaction.

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