Preparation method of high-activity nitrogen-doped carbon-loaded CoRu nano-alloy

Abstract

A preparation method of a high-activity nitrogen-doped carbon-loaded CoRu nano-alloy is used for enhancing pH universal hydrogen evolution, and is characterized by comprising the following steps: dissolving dopamine hydrochloride in an aqueous solution containing H2O2 and CuSO4. 5H2O, and magnetically stirring to form a uniform mixture; and pre-wetting carbon cloth with ethanol, immersing the pre-wetted carbon cloth in the dopamine solution for 10 minutes, taking out the pre-wetted carbon cloth, washing the pre-wetted carbon cloth with deionized water for three times, and carrying out vacuum drying to obtain the polydopamine modified carbon cloth marked as PDA / CC. And immersing the obtained PDA / CC into 20 mL of aqueous solution containing Co (NO3) 2.6 H2O and RuCl3 for 6 hours to realize metal ion adsorption. And washing and drying a sample, and calcining the sample in a tubular furnace at 700 DEG C in an N atmosphere for 2 hours to obtain the self-supporting nitrogen-doped porous carbon-loaded CoRu alloy material which is recorded as CoxRu (at) CN / CC. Through a synthesis strategy based on active ion capture and in-situ carbon thermal reduction, and through construction of a nitrogen-doped carbon cobalt ruthenium alloy nanostructure and a strong metal-carrier synergistic effect, efficient hydrogen overflow and establishment of stable active sites are realized; therefore, the performance bottleneck that high activity and high stability of a traditional electrocatalyst in a wide pH range are difficult to cooperate is broken through.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalytic materials technology, specifically relating to a self-supporting electrode for hydrogen evolution reactions across the entire pH range. It is prepared via a two-step method of room-temperature active ion capture and in-situ calcination, resulting in a nitrogen-doped porous carbon-supported cobalt-ruthenium alloy material. This material utilizes an in-situ carbothermal reduction process to effectively suppress the aggregation of cobalt-ruthenium alloy nanoparticles and generate abundant lattice defects as highly active reaction sites. Simultaneously, the introduced nitrogen element enhances the coupling effect between the metal species and the carbon matrix, thereby improving the material's durability and charge transfer performance. Background Technology

[0002] Hydrogen, with its zero-carbon emissions, high energy density, renewable nature, and environmental friendliness, has attracted widespread attention from the scientific community and offers a potential pathway to address energy and environmental challenges. Utilizing renewable energy sources (such as wind, solar, and tidal energy) to drive electrocatalytic water splitting to produce high-purity hydrogen is considered an effective strategy for achieving future sustainable development. Although platinum-based electrocatalysts exhibit excellent performance in the hydrogen evolution reaction, their high cost and limited natural reserves restrict their large-scale application.

[0003] To address this, researchers are dedicated to developing platinum-like alternative materials to reduce dependence on the precious metal platinum. Based on existing volcano plot data, cobalt sites exhibit moderate adsorption capacity for hydrogen intermediates, with a hydrogen adsorption free energy of approximately -0.17 eV. However, due to its low exchange current density, a significant kinetic barrier exists in the hydrogen desorption step. In contrast, ruthenium possesses excellent hydrogen desorption capacity, with an exchange current density similar to platinum and approximately 100 times that of cobalt, but its adsorption capacity for hydrogen intermediates is weaker. Given the limitations of single metals, the hydrogen spillover mechanism, by synergistically utilizing active sites with different functions, holds promise for overcoming the thermodynamic and kinetic limitations in the hydrogen evolution reaction, thus attracting widespread research interest. Therefore, constructing cobalt-ruthenium alloys is expected to combine the advantages of both, overcoming the shortcomings of cobalt in desorption kinetics and the deficiencies of ruthenium in adsorption capacity. However, many challenges remain in the experimental preparation of highly active and durable cobalt-ruthenium-based electrodes, such as the difficulty in precisely controlling the size and chemical ratio of the two metals during alloying, and the tendency of alloy nanoparticles to aggregate and detach during the reaction, leading to a decrease in catalytic activity. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems in the prior art and propose a synthesis strategy based on active ion capture and in-situ carbothermal reduction. By constructing a nitrogen-doped carbon cobalt-ruthenium alloy nanostructure and a strong metal-support synergistic effect, efficient hydrogen overflow and stable active sites are achieved, thereby breaking through the performance bottleneck of traditional electrocatalysts in which high activity and high stability are difficult to achieve in a wide pH range.

[0005] The technical solution of the present invention is as follows:

[0006] This invention provides a method for preparing highly active nitrogen-doped carbon-supported CoRu nanoalloys, comprising the following steps:

[0007] PDA / CC substrates were immersed in 20 mL of an aqueous solution containing Co(NO3)2·6H2O and RuCl3 for 3–9 hours to achieve metal ion adsorption; the molar ratio of Co to Ru was 2:1–20:1. The samples were then washed and dried, and then placed in a tube furnace and calcined at 600–800 °C for 2 hours under an inert or reducing atmosphere to obtain a self-supporting, nitrogen-doped, porous carbon-supported CoRu alloy rich in defect structures.

[0008] In the above method, the calcination temperature can be selected in the range of 600℃ to 800℃, for example, 600℃, 700℃ or 800℃, but is not limited to the listed values. Other unlisted temperature values ​​in this range are also applicable.

[0009] Preferably, the calcination temperature is 700°C.

[0010] The adsorption time of the metal ions can be adjusted within the range of 3 to 9 hours, for example, 3 hours, 6 hours or 9 hours, but is not limited to the listed values. Other unlisted times within this range are also applicable.

[0011] Preferably, the adsorption time is 6 hours.

[0012] The atmosphere used in the calcination process can be Ar, N2, or a mixture of H2 and Ar, such as Ar, N2, or 10% H2 / Ar, but is not limited to the types listed. Other suitable inert or reducing atmospheres can also be selected.

[0013] Preferably, the calcination atmosphere is N2.

[0014] The molar ratio of Co to Ru can be adjusted within the range of 2:1 to 20:1, for example, it can be 2:1, 5:1, 10:1, 15:1 or 20:1, but is not limited to the listed values. Other unlisted ratios within this range are also applicable.

[0015] Preferably, the molar ratio of Co to Ru is 10:1.

[0016] This invention synthesizes a series of self-supporting nitrogen-doped porous carbon-confined cobalt-ruthenium alloy electrodes through a systematic strategy based on active ion trapping and in-situ carbothermal reduction. Polymerized dopamine can effectively trap and uniformly disperse Co. 2+ / Ru 3+The ions are then transformed into a porous carbon-nitrogen network anchored on the carbon cloth, thus preventing the catalyst from detaching during the hydrogen evolution reaction. The formed carbon-nitrogen network has a confinement effect, which can inhibit the agglomeration and phase separation of metal nanoparticles during alloying; at the same time, the introduced nitrogen element anchors the cobalt-ruthenium alloy through coordination.

[0017] In a preferred embodiment of the present invention, the method comprises: immersing a PDA / CC substrate in 20 mL of an aqueous solution containing Co(NO3)2·6H2O and RuCl3 (molar ratio 10:1) for 6 hours to achieve metal ion adsorption. After washing and drying, the sample is placed in a tube furnace and calcined at 700°C for 2 hours under a N2 atmosphere to obtain a self-supporting, nitrogen-doped, porous carbon-supported, defect-rich CoRu alloy.

[0018] The present invention also provides CoRu alloy materials prepared according to any of the above-described preparation methods.

[0019] The present invention further provides the application of the CoRu alloy material in the hydrogen evolution reaction system.

[0020] This invention successfully fabricated a series of self-supporting nitrogen-doped porous carbon-confined cobalt-ruthenium alloy electrodes through a systematic active ion capture and in-situ carbothermal reduction strategy. Polymerized dopamine can effectively capture and uniformly disperse Co. 2+ / Ru 3+ The ions are converted into a porous carbon-nitrogen network anchored on the carbon cloth, thereby preventing the catalyst from falling off during the hydrogen evolution reaction.

[0021] The CoRu alloy prepared in this invention achieves a current density of 200 mA cm⁻² in acidic and alkaline media with overpotentials of only 175 mV and 426 mV, respectively, demonstrating excellent hydrogen evolution reaction performance across the entire pH range. In acidic solutions, after continuous operation at a current density of 100 mA cm⁻² for 100 hours, the activity decay of this material is negligible. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To further understand the present invention, it will be further described in conjunction with the accompanying drawings and embodiments.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the instruments and reaction materials used are commercially available unless otherwise specified.

[0025] Example 1

[0026] This invention provides a method for preparing highly active nitrogen-doped carbon-supported CoRu nanoalloys, comprising the following steps:

[0027] (1) Co 10 Ru@CN / CC Synthesis:

[0028] Dopamine hydrochloride was dissolved in an aqueous solution containing H₂O₂ and CuSO₄·5H₂O, and the solution was magnetically stirred to form a homogeneous mixture. Carbon cloth, pre-wetted with ethanol, was then immersed in the dopamine solution for 10 minutes. After removal, it was rinsed three times with deionized water and vacuum dried to obtain polydopamine-modified carbon cloth, denoted as PDA / CC. Subsequently, PDA / CC was immersed in 20 mL of an aqueous solution containing Co(NO₃)₂·6H₂O and RuCl₃ for 6 hours to achieve metal ion adsorption. After washing and drying, the sample was placed in a tube furnace and calcined at 700 °C for 2 hours under a N₂ atmosphere to finally obtain a self-supported nitrogen-doped porous carbon-supported defect-rich CoRu alloy, denoted as Co. 10 Ru@CN / CC.

[0029] Self-supporting nitrogen-doped porous carbon-loaded defect-rich CoRu alloy (Co 10 For the preparation process of Ru@CN / CC, please refer to [link / reference]. Figure 1 The flowchart.

[0030] Co 10 The morphology of Ru@CN / CC is as follows Figure 2 As shown in the scanning electron microscope (SEM) image, irregular nanoparticles are uniformly modified on the surface of the carbon cloth.

[0031] Co 10 Transmission electron microscopy (TEM) images of Ru@CN / CC material samples are shown below. Figure 3 CoRu nanoparticles with a size distribution (≤7nm) are encapsulated in a carbon-nitrogen matrix.

[0032] Co 10 High-resolution transmission electron microscopy (HRTEM) images of Ru@CN / CC material as follows: Figure 4 As shown, its lattice fringes are as follows Figure 5 As shown, the presence of lattice matching and interface point defects in the CoRu alloy is confirmed.

[0033] The linear sweep voltammetry (LSV) curve of this material in 0.5 M H₂SO₄ solution is shown in [link to relevant documentation]. Figure 6 .

[0034] The linear sweep voltammetry (LSV) curve of this material in 1M KOH solution is shown in [link to relevant documentation]. Figure 7 .

[0035] The linear sweep voltammetry (LSV) curve of this material in 1M PBS solution is shown in [link to relevant documentation]. Figure 8

[0036] The stability of this material in 0.5M H2SO4 solution is shown in [reference needed]. Figure 9 .

[0037] Prepared Co 10 Ru@CN / CC material was applied to a three-electrode system for hydrogen evolution reaction testing. Experimental results show that this material can achieve a hydrogen evolution reaction rate of 200 mA cm⁻¹ in acidic and alkaline media with overpotentials of only 175 mV and 426 mV, respectively. -2 The current density exhibits excellent hydrogen evolution reaction performance across all pH levels. In 0.5 M H₂SO₄ solution, at 100 mA cm⁻¹ cm⁻¹... -2 After 100 hours of continuous operation at the current density, the catalytic activity decay is negligible.

[0038] Example 2

[0039] The difference between this embodiment and Embodiment 1 is that the calcination temperature in step (1) is optimized: the calcination temperature is adjusted to 600 ℃ and 800 ℃ respectively, while the other conditions are exactly the same as in Embodiment 1, and the corresponding material is denoted as Co. 10 Ru@CN / CC-600℃, Co 10 Ru@CN / CC-800℃.

[0040] Co obtained 10 Ru@CN / CC-600℃, Co 10 The linear sweep voltammetry (LSV) curve of Ru@CN / CC-800℃ in 0.5 M H2SO4 solution is shown below. Figure 10 As shown.

[0041] Example 3

[0042] The difference between this embodiment and Example 1 is that the metal ion adsorption time is adjusted to 3 hours and 9 hours, while the other conditions are exactly the same as in Example 1. The resulting material is denoted as Co. 10 Ru@CN / CC-3h and Co 10 Ru@CN / CC-9h.

[0043] Co obtained 10 Ru@CN / CC-3h and Co10 The linear sweep voltammetry (LSV) curve of Ru@CN / CC-9h in 0.5M H2SO4 solution is shown below. Figure 11 As shown.

[0044] Example 4

[0045] The difference between this embodiment and Embodiment 1 is that the atmosphere used in the calcination process is Ar or a H2 / Ar mixture, while the other conditions are exactly the same as in Embodiment 1. The resulting material is denoted as Co. 10 Ru@CN / CC-Ar and Co 10 Ru@CN / CC-H2 / Ar.

[0046] Co obtained 10 Ru@CN / CC-Ar and Co 10 The linear sweep voltammetry (LSV) curve of Ru@CN / CC-H2 / Ar solution is shown below. Figure 12 As shown. Attached Figure Description

[0047] Figure 1 Co obtained in Example 1 10 Flowchart of Ru@CN / CC preparation;

[0048] Figure 2 Co obtained in Example 1 10 Scanning electron microscope (SEM) image of Ru@CN / CC.

[0049] Figure 3 Co obtained in Example 1 10 Transmission electron microscope image (TEM) of Ru@CN / CC;

[0050] Figure 4 Co obtained in Example 1 10 High-resolution transmission electron microscopy (HRTEM) image of Ru@CN / CC.

[0051] Figure 5 Co obtained in Example 1 10 Lattice fringes in the defect region of Ru@CN / CC;

[0052] Figure 6 Linear sweep voltammetry (LSV) curves of the 0.5 M H2SO4 solution obtained in Example 1.

[0053] Figure 7 The linear sweep voltammetry (LSV) curve of the 1M KOH solution obtained in Example 1 is shown.

[0054] Figure 8Linear sweep voltammetry (LSV) curves of the 1M PBS solution obtained in Example 1.

[0055] Figure 9 Co obtained in Example 1 10 For the stability of Ru@CN / CC in 0.5M H2SO4 solution, please refer to [reference needed]. Figure 9 ;

[0056] Figure 10 Co obtained in Example 2 10 Ru@CN / CC-600℃, Co 10 Linear sweep voltammetry (LSV) curve of Ru@CN / CC-800℃ in 0.5 M H2SO4 solution;

[0057] Figure 11 Co obtained in Example 3 10 Ru@CN / CC-3h and Co 10 Linear sweep voltammetry (LSV) curve of Ru@CN / CC-9h in 0.5M H2SO4 solution.

[0058] Figure 12 Co obtained in Example 3 10 Ru@CN / CC-Ar and Co 10 Linear sweep voltammetry (LSV) curves of Ru@CN / CC-H2 / Ar solution.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-activity nitrogen-doped carbon supported CoRu nanalloy, characterized in that, Comprising the following steps: Dopamine hydrochloride was dissolved in an aqueous solution containing H2O2 and CuSO4-5H2O, and a homogeneous mixture was formed by magnetic stirring. Carbon cloth was pre-wetted with ethanol and then immersed in the above dopamine solution for 10 minutes. After being taken out, it was washed with deionized water three times and vacuum dried to obtain polydopamine modified carbon cloth, denoted as PDA / CC. The obtained PDA / CC was immersed in a 20 mL aqueous solution containing Co(NO3)2-6H2O and RuCl3 for 6 hours to achieve metal ion adsorption. Subsequently, the sample was washed and dried, and calcined at 700°C for 2 hours under N2 atmosphere in a tube furnace to obtain a self-supported nitrogen-doped porous carbon supported CoRu alloy material, denoted as Co x Ru@CN / CC, where x ranges from 1 to 20.

2. The production method according to claim 1, characterized by, Co x In Ru@CN / CC, CoRu nanoparticles with size distribution not more than 7 nm are encapsulated in a nitrogen-doped carbon matrix. The in-situ carbothermal reduction process effectively inhibits the agglomeration of CoRu alloy nanoparticles and produces abundant lattice defects as high-activity reaction sites; at the same time, the introduced nitrogen element enhances the coupling between the metal species and the carbon matrix, thereby improving the durability and charge transfer performance of the material.

3. A method for preparing high active nitrogen-doped carbon supported CoRu nanalloy, characterized in that, The material only needs overpotential of 175 mV and 426 mV in acidic and alkaline media respectively to achieve a current density of 200 mA cm⁻², showing excellent hydrogen evolution reaction performance in the full pH range. In acidic solution, the activity attenuation of the material is negligible after running at a current density of 100 mA cm⁻² for 100 hours.

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