Carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst and its preparation method

Abstract

This invention discloses a carbon-coated platinum-nickel high-efficiency electro-hydrogen evolution catalyst and its preparation method. The method includes (i) the preparation of platinum-nickel alloy nanopowder catalyst; (ii) coating the surface of the platinum-nickel nano-hydrogen evolution catalyst with a carbon source; and (iii) the preparation of the carbon-coated platinum-nickel nano-hydrogen evolution catalyst. The method of this invention is simple and reliable. The carbon-coated platinum nanomaterial consists of a platinum core with exposed high-index crystal faces and a carbon film carbonized by high-temperature dopamine. The core provides the main active sites for hydrogen evolution, and the carbon film encapsulates the platinum nanoparticles, preventing platinum dissolution while allowing electrolyte penetration, thus improving its stability. The carbon layer on the surface of the platinum-nickel catalyst effectively encapsulates the platinum particles, allowing platinum to contact the electrolyte while preventing platinum particle dissolution, solving the technical problem of poor stability of platinum catalysts in acidic environments. Furthermore, it was found that the carbon film also interacts electronically with the metal particles within the core, regulating its internal electronic structure, thereby enhancing the HER catalytic activity of the material.

Description

Technical Field

[0001] This invention belongs to the field of nanocatalysts, specifically relating to a carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst and its preparation method. Background Technology

[0002] In recent years, fossil fuels have been gradually depleted, and their combustion byproducts impose a significant environmental burden. Against this backdrop, hydrogen energy stands out from other resources due to its high combustion efficiency, environmentally friendly combustion products, and renewable nature. Electrolysis of water to produce hydrogen is one of the effective ways to obtain hydrogen energy.

[0003] Platinum, due to its excellent electrical conductivity, corrosion resistance, stability, and suitable adsorption and desorption properties for hydrogen, has become one of the most important elements in hydrogen evolution catalysts. However, the limited reserves of platinum in the Earth's crust restrict its large-scale production. In recent years, many patents have been issued for preparing hydrogen evolution catalysts using non-noble transition metal materials, such as the transition metal iron-cobalt-nickel material "A highly efficient iron-cobalt layered bimetallic hydroxide coupled nickel-molybdenum hydroxide hydrogen evolution electrode and its preparation method" (CN112342565A), the sulfide "Preparation method of nickel-molybdenum-sulfur hydrogen evolution electrode" (CN102127775A), the carbide "A porous carbide hydrogen evolution electrode with honeycomb microstructure and its one-step preparation method" (CN110512233A), and the nitride "An electrolytic water hydrogen evolution catalyst and its preparation and application" (CN114045527A). However, compared with platinum-based catalysts, these non-noble transition metals cannot completely replace the most advanced electrocatalysts, such as platinum, in terms of performance and stability. One effective method is to form Pt-based alloy nanoparticles (NPs) with non-noble metal elements (such as Cu, Zn, Co, Ni). This not only reduces the overall load of Pt, making it economical, but also exhibits excellent hydrogen evolution performance due to the synergistic effect.

[0004] During crystal growth, to minimize total surface energy, crystal segments with lower surface energy are preferentially exposed. Exposure of high-energy portions is energy-disadvantageous, and these portions eventually disappear during crystal growth. High-refractive-index facets with high-energy surfaces generally perform better than those with low-energy surfaces. However, due to differences in reduction potential, atomic radius, and electronegativity among alloy components, the formation of mined single-metal NPs is already quite difficult, let alone the preparation of bimetallic alloy NPs. Noble metals with exposed high-index crystal faces are often used as catalysts for processes such as methanol, formic acid, ethanol oxidation, ORR, and ECL due to their high surface energy and selectivity. The performance advantage of high-index crystal faces of platinum in hydrogen evolution performance has been less studied. Experiments have shown that exposure of high-index crystal faces of platinum can effectively improve its hydrogen evolution performance, which is of great research significance for fully utilizing the unit atomic activity of platinum. Besides electrochemical performance, the stability of catalyst materials in practical applications is also a major issue. It is well known that active sites on the catalyst surface provide favorable chemical states for the formation or breaking of chemical bonds in the HER process. Therefore, the atomic structure surrounding the active sites on the catalyst surface is key to determining its catalytic performance. Under long-term operating conditions, highly active electrocatalysts will undergo significant and irreversible structural degradation. Summary of the Invention

[0005] This invention aims to overcome the problems and shortcomings of the prior art and, in response to the research difficulties in this field, provides a carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst and its preparation method.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst includes the following steps:

[0008] (i) Preparation of platinum-nickel alloy nanopowder catalyst

[0009] Prepare a reaction mother liquor and prepare a platinum-nickel alloy nanocatalyst by hydrothermal method. After the hydrothermal reaction is completed, cool to room temperature, centrifuge, wash and dry in sequence to obtain a platinum-nickel alloy nanopowder catalyst with exposed high index crystal faces.

[0010] The reaction mother liquor is a mixed solution prepared from glycine, polyvinylpyrrolidone, chloroplatinic acid and nickel chloride;

[0011] (ii) Carbon source coated on the surface of platinum-nickel nano-hydrogen evolution catalyst

[0012] The platinum-nickel alloy nanopowder catalyst with exposed high-index crystal planes obtained in step (i) was treated by a coating method to coat its surface with a carbon source.

[0013] (iii) Preparation of carbon-coated platinum-nickel nano-catalysts for hydrogen evolution

[0014] The product obtained in step (ii) was annealed and cooled in the furnace to obtain the carbon-coated platinum-nickel nano-hydrogen evolution catalyst.

[0015] In the above technical solution, the specific steps of the hydrothermal method are as follows: the reaction mother liquor is transferred to a polytetrafluoroethylene hydrothermal reactor and placed in an oven at 100℃~250℃ for 2h~7h.

[0016] In the above technical solution, the mass ratio of each component of the reaction mother liquor is:

[0017]

[0018] In the above technical solution, the coating method is a dopamine immersion method, specifically: Platinum-nickel nanocatalyst with exposed high index crystal faces is placed in a prepared Tris-HCl solution with a pH of 7.5-9, the Tris-HCl solution completely immerses the catalyst, then dopamine hydrochloride is added to the mixed solution, and the solution is soaked for 0.01h-100h. The solution is then centrifuged, washed, and dried to obtain the product.

[0019] In the above technical solution, the Tris solution is prepared by slowly adding hydrochloric acid dropwise to the Tris solution to adjust the pH of the solution.

[0020] In the above technical solution, the mass ratio of dopamine to platinum-nickel nanoparticle catalyst with high index crystal facets is 0.1-2:1-20.

[0021] In the above technical solution, the coating method is a glucose coating method, specifically: the platinum-nickel nanocatalyst with exposed high index crystal faces is transferred to 30 ml of 0.1-5 mM glucose solution, stirred evenly, and then transferred to 50 ml of hydrothermal reactor. The mixture is kept at 180℃-250℃ for 8-12 hours, and then centrifuged, washed, and dried to obtain the product.

[0022] In the above technical solution, the mass ratio of glucose to platinum-nickel nanopowder catalyst with high index crystal facets is 0.01-1.5:0.1-60.

[0023] In the above technical solution, the coating method is a PVP coating method, which specifically involves dissolving 0.1-5 mM PVP in anhydrous ethanol, immersing platinum-nickel nanocatalysts with exposed high-index crystal faces in the solution, mixing thoroughly, and finally drying in an oven to obtain the product.

[0024] In the above technical solution, the mass ratio of PVP to platinum-nickel nanopowder catalyst with high index crystal facet exposure is 4-300:0.1-60.

[0025] In the above technical solution, the annealing conditions are: holding at 150℃~1000℃ for 0.01h~17h in an inert atmosphere.

[0026] In the above technical solution, the inert atmosphere is any one or more of helium, neon, argon, krypton, or xenon.

[0027] A carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst is prepared by a method for preparing carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalysts.

[0028] The beneficial effects of this invention are:

[0029] This invention provides a carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst and its preparation method. The prepared carbon-coated platinum-nickel nanopowder catalyst exhibits several advantages. First, the carbon film on its surface can interact electronically with the metal core, regulating the electronic structure and thus improving the material's performance. Second, while permeating the electrolyte, the carbon film effectively mitigates the dissolution of platinum in the core in acidic electrolytes, resulting in excellent electrochemical hydrogen evolution catalysis and stability. The preparation method is simple, allowing for controllable preparation of the surface carbon film thickness by controlling the dopamine content, dopamine immersion time, carbonization temperature, and carbonization time. Compared to glucose coating and PVP coating methods, it demonstrates superior electrochemical hydrogen evolution performance. Compared to commercial platinum-carbon catalysts, it exhibits catalytic performance comparable to and far superior stability. No significant performance degradation was observed after 10,000 cycles at high current density. Attached Figure Description

[0030] Figure 1 These are, respectively, TEM images (a) and (b) of the PtNi NPs sample prepared according to the method described in Example 1 of this invention, TEM image (c) of PDA-PtNi NPs, and DEDS-TEM elemental distribution spectrum (d) of PtNi NPs with respect to Pt and Ni elements;

[0031] Figure 2 This is an EDS-TEM elemental distribution diagram of Pt, Ni, and C elements in PDA-PtNi NPs prepared according to the method described in Example 1 of this invention;

[0032] Figure 3 These are TEM images (ad) of PtNi NPs prepared according to the method described in Example 1 of this invention from various angles, and (e) and (f) schematic diagrams of their structure.

[0033] Figure 4 This is a comparison of XPS images of PDA-PtNi NPs and PtNi NPs prepared according to the method described in Example 1 of this invention;

[0034] Figure 5(a) a commercial platinum-carbon catalyst and (b) PDA-PtNiNPs prepared according to the method of Example 1 of this invention were subjected to a potential range of -1 to 0 V vs. RHE in 0.5 M H2SO4 solution at 50 mV s. -1 Electrochemical polarization curves before and after 10,000 sweep rate CV cycles;

[0035] Figure 6 The following are the polarization curves, Tafel curves, electrochemical impedance spectra, and capacitance curves of the PDA-PtNi NPs prepared as described in Examples 2-5 of this invention after annealing at temperatures of 450℃, 500℃, 550℃, and 600℃: (a) polarization curves, (b) Tafel curves, (c) electrochemical impedance spectra, and (d) capacitance curves.

[0036] Figure 7 The following are the polarization curves, Tafel curves, electrochemical impedance spectroscopy, and capacitance curves of the PtNi NPs catalyst prepared in Examples 6-10 of this invention after being immersed in dopamine solution for 6 h, 12 h, 18 h, and 24 h, respectively.

[0037] Figure 8 The following are the polarization curves, Tafel curves, electrochemical impedance spectroscopy, and capacitance curves of PDA-PtNi NPs prepared according to Examples 11-13 of the present invention after being soaked in 15 mg, 30 mg, and 45 mg of dopamine, respectively.

[0038] Figure 9 The following are the polarization curves, Tafel curves, electrochemical impedance spectroscopy, and capacitance curves of PDA-PtNi NPs, glucose-PtNi NPs, PVP-PtNi NPs, PtNi NPs, and commercial platinum-carbon catalysts prepared in Comparative Examples 1 and 14-15 of this invention.

[0039] Figure 10 This is a TEM image of the PVP-PtNi NPs prepared according to Example 15 of the present invention;

[0040] Figure 11 The PDA-PtNi NPs (a)(d) prepared according to the method described in Example 1 of this invention, commercial platinum carbon (b)(e) and PtNi NPs (c)(f) were subjected to a potential range of -1 to 0 V vs. RHE in 0.5 M H2SO4 solution at 50 mV s -1 SEM images of the topography before and after 10,000 CV cycles at a scanning speed.

[0041] Wherein: PtNi NPs are platinum-nickel nanoparticles before carbon coating, and PDA-PtNi NPs are platinum-nickel hydrogen evolution catalysts coated with PDA carbon film.

[0042] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 24 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0046] from Figure 1 It can be seen that due to the exposure of high-index crystal planes, the surface of PtNi NPs nanoparticles exhibits a distinct concave structure, and platinum and nickel elements are uniformly present within it.

[0047] from Figure 2 It can be seen that the carbon film on the surface of PDA-PtNi NPs is an amorphous carbon layer with a thickness of about 5 nm, which is uniformly coated on the platinum-nickel core.

[0048] from Figure 3 TEM images taken from different angles show that the PtNi NPs nanonucleus is a concave cubic structure that differs from a standard cubic structure.

[0049] from Figure 4 The XPS comparison diagram of PDA-PtNi NPs and PtNi NPs prepared in Example 1 shows that the coated carbon film and the internal metal core have electronic interactions, which leads to the shift of XPS peak positions.

[0050] from Figure 5The PDA-PtNi NPs (b) prepared in Example 1 shown herein, and the commercial platinum-carbon catalyst (a), were reacted in 0.5 M H₂SO₄ solution at a potential range of -1 to 0 V vs. RHE at a potential of 50 mV s⁻¹. -1 The electrochemical polarization curves before and after 10,000 sweep rate CV cycles show that PDA-PtNi NPs have more durable stability under acidic conditions compared to commercial platinum-carbon.

[0051] from Figure 11 The PDA-PtNi NPs (a)(d), commercial platinum-carbon (b)(e), and PtNi NPs (c)(f) prepared in Example 1 are shown in 0.5 M H₂SO₄ solution with a potential range of -1 to 0 V vs. RHE of 50 mV s. -1 The SEM images before and after 10,000 CV cycles at a high sweep rate show that after a long period of testing, the surface of commercial platinum carbon aggregates into spheres, while the surface structure of PtNi NPs collapses. However, the PDA-PtNi NPs structure still maintains a loose and porous structure, and its performance does not change significantly.

[0052] Example 2

[0053] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to stand for 6 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 450 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0054] Example 3

[0055] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 6 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0056] Example 4

[0057] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to stand for 6 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 550 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0058] Example 5

[0059] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to stand for 6 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 600 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0060] Example 6

[0061] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 6 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0062] Example 7

[0063] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to stand for 12 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0064] Example 8

[0065] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 18 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0066] Example 9

[0067] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 24 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0068] Example 10

[0069] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 30 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500 °C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0070] Example 11

[0071] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 220°C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 15 mg of dopamine was added to this solution and allowed to soak for 24 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500°C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0072] Example 12

[0073] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 220°C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 30 mg of dopamine was added to this solution and allowed to soak for 24 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500°C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0074] Example 13

[0075] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a 500 ml polytetrafluoroethylene hydrothermal reactor and placed in an oven at 220°C for 7 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. Next, 30 mg of the high-index platinum-nickel nanopowder catalyst was mixed thoroughly in a Tris solution at pH 8.5. Then, 45 mg of dopamine was added to this solution and allowed to soak for 24 hours. Afterward, the mixture was centrifuged, washed, and dried sequentially. Finally, the dried powder was placed in a crucible and heated at 500°C for 3 hours under a mixed inert atmosphere of helium and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0076] Example 14

[0077] First, a homogeneous mixture was prepared by mixing 1.52 g of glycine, 8.8 g of polyvinylpyrrolidone, 0.414 g of chloroplatinic acid, 0.044 g of nickel chloride, and 360 ml of deionized water. This mixture was then transferred to a polytetrafluoroethylene hydrothermal reactor and placed in an oven at 220°C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried to obtain a platinum-nickel alloy nanoparticle catalyst with exposed high-index crystal faces. The high-index crystal facet-exposed platinum-nickel nanoparticle catalyst was transferred to 30 ml of 0.1 mM glucose solution, stirred thoroughly, and then transferred to a 50 ml hydrothermal reactor. The mixture was heated at 200°C for 12 hours, centrifuged, washed, and dried to obtain the product. Finally, the dried powder was placed in a crucible and heated at 550°C for 4 hours under a mixed inert atmosphere of krypton and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanoparticle hydrogen evolution powder catalyst with exposed high-index crystal faces was obtained.

[0078] Example 15

[0079] First, a homogeneous mixture of 1.52 g glycine, 8.8 g polyvinylpyrrolidone, 0.414 g chloroplatinic acid, 0.044 g nickel chloride, and 360 ml deionized water was prepared. This mixture was then transferred to a polytetrafluoroethylene hydrothermal reactor and placed in an oven at 200 °C for 6 hours. After cooling to room temperature, the mixture was centrifuged, washed, and dried sequentially to obtain a platinum-nickel alloy nanopowder catalyst with exposed high-index crystal faces. 1 mM PVP was dissolved in 5 ml anhydrous ethanol, and 30 mg of the platinum-nickel nanopowder catalyst with exposed high-index crystal faces was then immersed in the ethanol, thoroughly mixed, and finally dried in an oven to obtain the product. Finally, the dried powder was placed in a crucible and heated at 500 °C for 6 hours under a mixed inert atmosphere of argon and neon. After cooling to room temperature, a carbon-coated platinum-nickel nanopowder catalyst with exposed high-index crystal faces was obtained.

[0080] pass Figure 10 The TEM images shown indicate that, compared to dopamine-coated carbon films, the carbon films prepared by the PVP coating method have poor control over film thickness and uniformity. The resulting carbon films are unevenly distributed and prone to aggregation. Therefore, for catalyst materials requiring exposed surface active sites, excessively thick or uneven carbon films can block the contact between the internal metal active sites of PtNi NPs and the electrolyte, leading to poor HER catalytic performance. Furthermore, by conducting relevant tests on the catalysts prepared in Examples 1 and 14-15, the influence of different coating methods on the final catalyst performance was determined, and the results are as follows: Figure 9 As shown in the figure, the performance of PtNi NPs catalysts after carbon coating is improved to a certain extent. However, compared with the other two preparation methods, the PDA-PtNi NPs catalyst prepared by the dopamine coating method has the best electrochemical hydrogen evolution performance.

[0081] The effect of annealing temperature on the final performance of the catalysts prepared in Examples 2-5 was determined by relevant testing, and the results are as follows: Figure 6 As shown, the performance of the catalyst first increases with the increase of annealing temperature, reaching its best performance at 500℃, and then begins to decline. This may be because the high-index crystal planes of PtNi NPs gradually collapse as the temperature increases, leading to a decrease in their performance.

[0082] The effect of immersion time in dopamine solution on the final performance of the catalysts prepared in Examples 6-10 was determined by relevant tests. The results are as follows: Figure 7 As shown, the carbon film coating on the surface of PtNi NPs gradually thickens with prolonged soaking time. The best hydrogen evolution performance is achieved when the soaking time is 24h. When the time is extended further, the carbon film becomes too thick, which is not conducive to the contact between the electrolyte and the active sites.

[0083] The effect of dopamine addition on the final performance of the catalysts prepared in Examples 11-13 was determined by relevant testing, and the results are as follows: Figure 8 As shown in the figure, the mass of dopamine has no significant effect on the electrochemical performance of PDA-PtNi NPs.

[0084] The principle of this invention (taking the dopamine immersion method as an example):

[0085] This invention provides a simple and reliable method for preparing carbon-coated platinum-nickel nanopowder hydrogen evolution catalysts. First, a simple hydrothermal method is employed, utilizing the specific selectivity of surfactants for high-index platinum crystal facets to prepare platinum nano-alloy powders with exposed high-index crystal facets. By controlling the ratio of metal reagent to surfactant, platinum with different exposed crystal facets is obtained. The platinum with exposed high-index crystal facets in the core provides the main active sites for hydrogen evolution. Then, using dopamine as a carbon source, the platinum nano-alloy powder is immersed in a dopamine solution, ensuring its surface is fully coated with dopamine. Next, a carbon film is formed at high temperature under an inert atmosphere, coating the catalyst material surface. The thickness of the surface carbon film is controlled by adjusting the ratio of dopamine to platinum nano-alloy powder, the immersion time of the platinum nanopowder in the dopamine solution, and the high-temperature carbonization temperature and time. The surface carbon film allows electrolyte permeation while slowing the dissolution of platinum in the core, thereby improving its stability in acidic electrolytes. Simultaneously, by controlling the ratio of dopamine to platinum nanopowder, the dopamine immersion time, and the high-temperature carbonization temperature and time, the carbon-coated platinum nanopowder hydrogen evolution catalyst can be prepared in a controllable manner.

[0086] Experimental results demonstrate that the hydrogen evolution performance of carbon-coated platinum nanocatalysts is significantly better than that of uncoated platinum nanocatalysts, and their hydrogen evolution stability in 0.5M H2SO4 electrolyte is significantly improved.

[0087] 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 method for preparing a carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst, characterized in that: Includes the following steps: (i) Preparation of platinum-nickel alloy nanopowder catalyst Prepare a reaction mother liquor and prepare a platinum-nickel alloy nanocatalyst by hydrothermal method. After the hydrothermal reaction is completed, cool to room temperature, centrifuge, wash and dry in sequence to obtain a platinum-nickel alloy nanopowder catalyst with exposed high index crystal faces. The reaction mother liquor is a mixed solution prepared from glycine, polyvinylpyrrolidone, chloroplatinic acid and nickel chloride; The mass ratio of each component in the mother liquor is as follows: 2 to 10 parts glycine; 15 to 60 parts of polyvinylpyrrolidone; Chloroplatinic acid 0.5 to 5 parts; Nickel chloride 0.05 to 0.5 parts; 1000 to 5000 parts deionized water; (ii) Carbon source coated on the surface of platinum-nickel nano-hydrogen evolution catalyst The platinum-nickel alloy nanopowder catalyst with exposed high-index crystal planes obtained in step (i) was treated by a coating method to coat its surface with a carbon source. (iii) Preparation of carbon-coated platinum-nickel nano-catalysts for hydrogen evolution The product obtained in step (ii) was annealed and cooled in the furnace to obtain the carbon-coated platinum-nickel nano-hydrogen evolution catalyst.

2. The preparation method of the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 1, characterized in that: The specific steps of the hydrothermal method are as follows: the reaction mother liquor is transferred to a polytetrafluoroethylene hydrothermal reactor and placed in an oven at 100℃~250℃ for 2h~7h.

3. The preparation method of the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 1, characterized in that: The coating method is a dopamine immersion method, specifically: platinum-nickel nanocatalysts with exposed high-index crystal faces are placed in a prepared Tris-HCl solution with a pH of 7.5–9, and then dopamine hydrochloride is added to the mixed solution. The mixture is immersed for 0.01 h–100 h, centrifuged, washed, and dried sequentially to obtain the product. The Tris-HCl solution is prepared by slowly adding hydrochloric acid dropwise to a Tris solution to adjust the pH of the solution. The mass ratio of dopamine hydrochloride to platinum-nickel nanopowder catalyst is 0.1–2:1–20.

4. The method for preparing the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 1, characterized in that: The coating method is a glucose coating method, specifically: the platinum-nickel nanocatalyst with exposed high-index crystal faces is transferred to a 0.1 mM to 5 mM glucose solution, stirred evenly, and then transferred to a hydrothermal reactor. It is kept at 180℃ to 250℃ for 8 h to 12 h, and then centrifuged, washed, and dried to obtain the product. The mass ratio of glucose to platinum-nickel nanopowder catalyst with exposed high-index crystal faces is 0.01 to 1.5: 0.1 to 60.

5. The preparation method of the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 1, characterized in that: The coating method is a PVP coating method, specifically: 0.1 mM to 5 mM PVP is dissolved in anhydrous ethanol, and then platinum-nickel nanocatalysts with exposed high-index crystal faces are immersed in it, thoroughly mixed, and finally dried in an oven to obtain the product; the mass ratio of PVP to platinum-nickel nanopowder catalyst with exposed high-index crystal faces is 4 to 300: 0.1 to 60.

6. The method for preparing the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 1, characterized in that: The annealing conditions are as follows: heat treatment at 150℃~1000℃ for 0.01h~17h under an inert atmosphere.

7. The method for preparing the carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst according to claim 6, characterized in that: The inert atmosphere is any one or more of helium, neon, argon, krypton, or xenon.

8. A carbon-coated platinum-nickel high-efficiency electrochemical hydrogen evolution catalyst, characterized in that: Prepared by the method according to any one of claims 1 to 7.

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