A supported Ru6 cluster catalyst for hydrogen evolution in alkaline water electrolysis, its preparation method and applications

Abstract

A Ru6 cluster catalyst supported for alkaline water electrolysis and hydrogen evolution (HER), its preparation method, and its uses. This invention relates to an alkaline water electrolysis and HER supported Ru6 cluster catalyst, wherein precisely six Ru atoms are supported as a cluster on a Ketjen black oxide support, the Ru-Ru coordination number is 2.5-2.7, it has a planar structure, and the Ru loading is 0.5-2.4 wt%. The catalyst is expressed as Ru6 / KBO, and is prepared by calcining and reducing precisely numbered Ru6 nanoclusters in a Joule furnace and then supporting them on Ketjen black oxide. This invention prepares Ru6 clusters supported on KBO, which exhibit good HER catalytic activity under alkaline conditions, high Ru atom utilization efficiency, stable catalyst structure, significantly improved electrocatalytic HER performance, and long-lasting catalytic efficacy.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials, specifically relating to a Ru6 cluster catalyst supported for hydrogen evolution in alkaline water electrolysis, its preparation method, and its applications. Background Technology

[0002] With the increasing global demand for clean energy to address climate change and energy security, hydrogen has gained widespread attention as a clean and efficient energy carrier. Water electrolysis is a sustainable method for hydrogen production, utilizing electricity generated from renewable energy sources (such as solar and wind power) to decompose water into hydrogen and oxygen. Among various water electrolysis technologies, alkaline water electrolysis (AWE) is a relatively mature system. Its working principle involves water decomposition through electrode reactions in an alkaline electrolyte (usually potassium hydroxide or sodium hydroxide solution). Compared to other water electrolysis technologies (such as proton exchange membrane electrolysis and solid oxide electrolysis), alkaline water electrolysis offers advantages such as lower cost and simpler equipment. In alkaline water electrolysis, the hydrogen evolution reaction (HER) is a crucial half-reaction, and its efficiency directly affects the overall efficiency of hydrogen production. However, the kinetics of the HER are sluggish in an alkaline environment. This is because in an alkaline medium, water molecules need to first dissociate into hydrogen ions (H+). + ) and hydroxide ions (OH) - The hydrogen ions then accept electrons to generate hydrogen gas. Compared to the hydrogen evolution reaction in acidic media, the hydrogen evolution reaction in alkaline media involves an additional, slower step of water molecule dissociation, resulting in a higher overpotential. The presence of this overpotential increases energy consumption during electrolysis and reduces hydrogen production efficiency. Noble metal catalysts are commonly used to lower the overpotential of the hydrogen evolution reaction.

[0003] In the field of alkaline water electrolysis for hydrogen evolution, an ideal catalyst should possess characteristics such as high catalytic activity, good stability, and low cost. Platinum-based catalysts are recognized as highly efficient HER catalysts, but their scarcity and high cost hinder their widespread application, thus prompting the development of highly efficient non-Pt-based catalysts. Ru, with a much lower cost than Pt, possesses similar hydrogen adsorption strength, a lower water dissociation energy barrier, and good durability, making it considered an ideal alternative to Pt-based catalysts. In recent years, Ru has been extensively studied as the catalytic active center for alkaline HER; however, as a precious metal, low Ru utilization leads to high catalyst costs. Therefore, reducing the precious metal loading while maintaining high activity and stability is crucial for the design of high-performance catalysts. An obvious option is to reduce the size to nanoclusters or single atoms to significantly improve atom utilization efficiency. Single-atom catalysts have discrete metal centers, theoretically achieving 100% metal utilization; however, they cannot provide multiple metal atom sites, resulting in relatively singular adsorption of active intermediates, making them unsuitable for regulating the simultaneous adsorption of multiple H* and OH*. Precisely numbered clusters possess well-defined composition, size, and structure, enabling accurate identification of active sites and establishing clear catalyst structure-activity relationships. This provides a foundation for a deeper understanding of the hydrogen evolution reaction (HER) mechanism and further optimization of catalyst performance. On the other hand, selecting a support material with a high specific surface area is crucial for reducing noble metal loading. Ketjen black oxide, with its abundant pore structure and large specific surface area, not only provides numerous attachment sites for the supported active material but also fully exposes the active centers of the catalyst during the catalytic reaction, enhancing catalytic activity. Furthermore, ruthenium-based catalysts, due to their high surface energy, face challenges such as relatively strong H adsorption and severe Ru atom aggregation. This not only makes the Tafel step challenging but also leads to the loss of active sites. Metal-support interactions can adjust the surface electronic structure, allowing active sites to possess optimal hydrogen adsorption energies, thereby enhancing catalytic activity for HER. Therefore, the active component can be a metal cluster catalyst with a precise number of atoms, and the support can be a carbon support.

[0004] CN115584536A discloses a ruthenium nanocluster catalyst for alkaline electrochemical hydrogen evolution reaction. The ruthenium nanocluster catalyst is a composite material in which ruthenium oxide is supported on a carbon support in the form of nanoclusters. Its preparation method includes the following steps: S1. Crushing dried agricultural waste and mixing it with an activator, then calcining to obtain biochar; S2. Stirring, filtering, and washing the biochar obtained in S1. in hydrochloric acid aqueous solution to obtain a carbon support; S3. Dispersing ruthenium salt in a solvent, then adding the carbon support obtained in S2., mixing and dispersing evenly, and then rotary drying to obtain a precursor material; S4. Heat-treating the precursor material obtained in S3. to obtain the ruthenium nanocluster catalyst.

[0005] CN118403074A discloses a method for preparing graphitic carbon nitride-supported Ru single-atom and Ru atom cluster nanomaterials, comprising the following steps: S1. Weigh 1,10-phenanthroline into a round-bottom flask containing anhydrous ethanol, then add ruthenium chloride solution dropwise into a round-bottom beaker, add a magnetic stir bar, stir vigorously at room temperature, then add carbon nitride, and sonicate to dissolve for a period of time. S2. Magnetically stir the solution obtained in step S1, reflux, evaporate the solvent, and then dry the resulting powder in a vacuum drying oven. After drying, grind it evenly, place it in a crucible, and then place the crucible in a tube furnace for pyrolysis under an argon atmosphere. After natural cooling to room temperature, obtain the black final product Ru. SA+AC .

[0006] CN115584536A discloses a ruthenium nanocluster catalyst for alkaline electrochemical hydrogen evolution reaction (HER). The preparation method includes the following steps: S1. Crushing dried agricultural waste and mixing it with an activator, then calcining to obtain biochar; S2. Stirring, filtering, and washing the biochar obtained in S1. in hydrochloric acid aqueous solution to obtain a carbon support; S3. Dispersing ruthenium salt in a solvent, then adding the carbon support obtained in S2., mixing and dispersing evenly, and then rotary drying to obtain a precursor material; S4. Heat-treating the precursor material obtained in S3. to obtain the ruthenium nanocluster catalyst. In this patent, ruthenium exists in the form of oxide nanoclusters. It is not a cluster of metallic ruthenium, and its HER catalytic activity is not good.

[0007] CN114318362A discloses a method for preparing a ruthenium nanocluster hydrogen evolution electrocatalyst, comprising the following steps: Step 1, placing a zinc zeolite imidazole framework in a tube furnace and performing high-temperature carbonization in a hydrogen-argon mixture to obtain a nitrogen-doped carbon nanoframework; Step 2, immersing the nitrogen-doped carbon nanoframework in a phytic acid solution, stirring, and then transferring it to an evaporation container for evaporation-induced self-assembly to obtain a phytic acid-modified nitrogen-doped carbon nanoframework; Step 3, immersing the phytic acid-modified nitrogen-doped carbon nanoframework in a hydrated ruthenium trichloride solution, stirring, and then obtaining a ruthenium nanocluster hydrogen evolution electrocatalyst.

[0008] CN111906327A discloses a method for synthesizing ruthenium nanocluster electrocatalysts for hydrogen production by water electrolysis. Carbon nanotubes and N,N-dimethylformamide are placed in a round-bottom flask and sonicated. Ruthenium trichloride is then added dropwise to the flask, and the mixture is stirred in an oil bath at 140°C for 6 hours. The reacted material is then centrifuged, washed three times, and dried. 20 mg of the dried material is added to 12 mL of 3 wt% hydrogen peroxide solution and reacted hydrothermally at 180°C for 3 hours to obtain a composite material of ruthenium nanoclusters and carbon nanotubes.

[0009] The Ru clusters reported in the prior art are used for HER reaction catalysis, but the Ru6 cluster of the present invention has a precise number of atoms, low loading of the noble metal Ru, high atom utilization, and cost advantage; in addition, the Ru6 cluster has superior activity and stability at high current density.

[0010] The inventors previously disclosed a Ru3 cluster catalyst with precise atomic number supported for alkaline water electrolysis and hydrogen evolution in patent CN119082792A. However, the Ru3 cluster catalyst exhibits lower activity and stability at high current densities compared to the Ru6 cluster catalyst. (At 250 mA / cm²) -2 The overpotential of the Ru3 cluster at the given current density is 144.3 mV, while that of the Ru6 cluster is 128.9 mV.

[0011] The synthesis of Ru6 clusters has been reported in existing technologies such as Inorg. Chem. 1982, 21, 3816-3820, Journal of Organometallic Chemistry 669 (2003) 44-47, and Organometallics 1997, 16, 4531-453, but they have not been applied to the HER reaction. The use of Ru6 clusters as catalytic active centers supported on Ketjen black oxide for electrocatalytic basic HER has not been previously reported. Summary of the Invention

[0012] To address the shortcomings of supported Ru catalysts in alkaline hydrogen evolution reactions (HER) such as low atom utilization, low catalytic activity, or short catalytic lifetime, this invention proposes a supported catalyst using Ru6 clusters as the catalytic active center. This results in a composite material with high catalytic activity, stable structure, and long lifespan, suitable for HER reactions under alkaline conditions. Due to its ultra-low loading and good stability, it represents a novel alkaline HER electrocatalytic material.

[0013] The present invention achieves the above objectives through the following technical solutions:

[0014] The first objective of this invention is to provide an alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst, wherein exactly 6 Ru atoms are supported as a cluster on a Ketjen black oxide support, the Ru-Ru coordination number is 2.5-2.7, the structure is planar, and the Ru loading is 0.5-2.4 wt%.

[0015] Further, the Ru loading is 0.5-2.4 wt%; preferably, the Ru loading is 1.4-2.1 wt%.

[0016] The inventors have discovered that the Ru6 cluster-supported catalyst synthesized in this invention exhibits excellent basic hydrogen evolution catalytic activity and catalytic stability. Furthermore, there are no other reports on the basic hydrogen evolution activity of Ru6 clusters with precisely defined atomic numbers, and the stability of currently reported catalysts at high current densities is unsatisfactory. Generally, in the preparation of supported catalysts, the slow heating rate of ordinary tube furnaces and the long residence time of materials at high temperatures can cause noble metal agglomeration, forming nanoparticles. This invention employs a Joule furnace capable of reaching extremely high temperatures within seconds for the calcination process, allowing for precise control of the heating process and targeted heat treatment at specific temperatures. This avoids rapid agglomeration of materials at high temperatures and minimizes interference with the original structure of the precursor. Catalysis is generally considered a surface reaction; cluster agglomeration into particles reduces the utilization rate of surface atoms, slightly increasing performance, but resulting in low atom utilization and increased cost. This invention regulates the size and dispersion of Ru6 clusters on the Ketjen black oxide support by rapid heating and cooling in a Joule furnace and by controlling the amount of precursor loading. The catalyst is characterized by XRD crystal diffraction, electron microscopy and other techniques.

[0017] This invention also provides a method for preparing the above-mentioned supported Ru6 cluster catalyst, comprising the following steps:

[0018] (S1) Weigh out Ketjen black, treat it with nitric acid, wash it, and dry it to obtain Ketjen black oxide;

[0019] (S2) Take the Ru-derived precursor [NBu4]2[Ru6C(CO)] 16 The precursor was ultrasonically dispersed in a solvent and slowly added to a solution in which Ketjen black oxide was uniformly dispersed. The mixture was stirred, centrifuged, washed, and dried to obtain a precursor. The precursor was then rapidly calcined in a Joule furnace under an inert gas atmosphere at a temperature of 350-500℃ for 100-120 seconds. After natural cooling, an atomically precise Ru6 catalyst was obtained supported on Ketjen black oxide.

[0020] Furthermore, in step (S1), the concentration of nitric acid is 5-6 mol / L. -1 The mass-to-volume ratio of Ketjen black to nitric acid is 1g:100-150mL. Nitric acid treatment is carried out at 60-80℃ for 20-30 hours. There are no particular restrictions on washing and drying, such as washing with water or drying in an oven.

[0021] Further, in step (S2), the organic solvent is one of dichloromethane and tetrahydrofuran; the amount of Ru source and solvent is such that the concentration of Ru source precursor in the solvent is 0.1-0.5 mg / mL; the solvent uniformly dispersed with Ketjen black oxide has a concentration of 1-5 mg / mL in the solvent; the magnetic stirring is carried out for a period of time, which is 9-12 hours at room temperature; the stirring time should not be too short, otherwise the loading may be incomplete. This can be judged by the color of the solution after stirring and centrifugation. If the solution is clear and transparent, it indicates that the loading is complete; if the solution is dark in color, it indicates that the loading is incomplete. This step will directly determine the electrochemical HER performance of the synthesized Ru6 cluster; the washing solution is the corresponding organic solution.

[0022] Furthermore, in step (S2), the inert gas is a nitrogen atmosphere, and the calcination temperature is 400-500℃. The ligands in the precursor are burned off. The purpose of removing the ligands is to expose the active sites, making the clusters bind more firmly to the support. This is beneficial for enhancing the activity of the Ru6 clusters while ensuring good stability. The calcination temperature should not be higher, and the calcination time should not be longer; otherwise, the Ru6 clusters will further agglomerate to form large particles.

[0023] Furthermore, in step (S2), the rapid heating is achieved using a Joule furnace, which can rapidly heat the temperature to the target temperature within 1-2 seconds.

[0024] A third objective of this invention is to provide the application of the above-mentioned alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst in the electrocatalytic HER under alkaline conditions. The Ru6 cluster-based supported catalyst provided by this invention has high atom utilization, high catalytic activity, and can remain stable for a long time. It can catalyze the reduction of hydrogen at room temperature, and the product is non-toxic and harmless.

[0025] A fourth objective of this invention is to provide a method for water electrolysis, wherein the hydrogen electrode uses the aforementioned alkaline water electrolysis hydrogen evolution supported Ru-based catalyst Ru6 / KBO as the HER catalyst. Compared to the prior art, this invention has the following advantages:

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention prepares atomically precise Ru6 clusters supported on Ketjen black oxide, which exhibit excellent basic HER electrocatalytic activity, high Ru utilization efficiency, and stable catalyst structure. By using the Ru6 cluster as the catalytic active center, this invention significantly improves the electrocatalytic HER performance and provides sustained catalytic efficacy. Attached Figure Description

[0028] Figure 1 Transmission electron microscopy (TEM) image of the Ketjen black oxide catalyst prepared for Preparation Example 1.

[0029] Figure 2 Transmission electron microscopy (TEM) image of the Ru6 / KBO catalyst prepared in Example 1.

[0030] Figure 3 Aberration-corrected transmission electron microscopy (AC-TEM) image of the Ru6 / KBO catalyst prepared in Example 1.

[0031] Figure 4 X-ray powder diffraction (XRD) pattern of the catalyst prepared in Example 1.

[0032] Figure 5 This is a schematic diagram of the structure of the Ru6 / KBO catalyst prepared in this embodiment.

[0033] Figure 6 Transmission electron microscopy (TEM) image of the catalyst prepared for Comparative Example 1.

[0034] Figure 7 Transmission electron microscopy (TEM) image of the catalyst prepared for Comparative Example 2.

[0035] Figure 8 Transmission electron microscopy (TEM) image of the catalyst prepared for Comparative Example 4.

[0036] Figure 9 Aberration transmission electron microscopy (AC-TEM) image of the catalyst prepared for Comparative Example 7.

[0037] Figure 10 The LSV diagrams for the hydrogen evolution reaction of the catalysts prepared in Example 1, Comparative Examples 6, 7, 8, 9, and 10 in 1M KOH solution are shown.

[0038] Figure 11 This is a stability graph of the catalysts prepared in Example 1, Comparative Examples 7, 8, and 9 in 1M KOH solution. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. The following embodiments are provided to better understand this invention, but do not limit the invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods.

[0040] Unless otherwise specified, "parts" in the embodiments of the present invention refers to parts by mass, and "%" refers to percentage by mass unless otherwise specified.

[0041] Preparation Example 1

[0042] Pretreatment of the carrier: Weigh 200 mg of Ketjen black and add it to 30 ml of 6 mol L. -1After ultrasonically agitating for 5 minutes to disperse evenly, the mixture is magnetically stirred in a 70℃ oil bath for 24 hours. After stirring, the mixture is cooled to room temperature, then centrifuged with deionized water until neutral, dried in an 80℃ oven, ground, and ready for use.

[0043] Figure 1 Transmission electron microscopy (TEM) image of the Ketjen black oxide support prepared in Example 1. As can be seen from the image, the support has a relatively uniform, loose, porous structure formed by the stacking of nanoparticles.

[0044] Example 1

[0045] A method for preparing a Ru6 cluster supported by alkaline water electrolysis hydrogen evolution includes the following steps:

[0046] Take 5 mg of the synthesized precursor cluster [NBu4]2[Ru6C(CO)] 16 [NBu4]2[Ru6C(CO)] was ultrasonically dissolved in 10 ml of dichloromethane and added dropwise to 100 ml of dichloromethane containing 100 mg of Ketjen black oxide carrier. The mixture was stirred while adding the mixture and magnetically stirred for 12 h. The mixture was then centrifuged and washed twice at 10,000 rpm. The resulting black product was [NBu4]2[Ru6C(CO). 16 The Ru6 / KBO was dried in a vacuum drying oven for later use. A portion of the above black product was placed on carbon cloth and rapidly heated to 400°C in a Joule furnace. It was calcined under a N2 atmosphere for 120 seconds, then rapidly cooled naturally to obtain Ru6 / KBO. After natural cooling to room temperature, an alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst was obtained. Inductively coupled plasma atomic emission spectrometry (ICP) analysis showed that the Ru loading in the composite catalyst prepared in Example 1 was 1.487 wt%.

[0047] Figure 2 The image shows a transmission electron microscope (TEM) image of the Ru6 / KBO catalyst prepared in this embodiment. No visible black spots belonging to Ru nanoparticles were observed in the image.

[0048] Figure 3 This is an aberration-corrected transmission electron microscope (AC-TEM) image of the alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst prepared in Example 1. The image shows that the cluster consists of 6 Ru atoms, with a size of approximately 1 nm, uniformly dispersed on the support without agglomeration.

[0049] Figure 4 The image shows the X-ray diffraction (XRD) pattern of the alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst prepared in Example 1. No characteristic peaks of Ru were observed compared with the standard card, indicating that no Ru particles were present in the catalyst, meaning that the Ru6 clusters did not agglomerate.

[0050] Table 1 shows the EXAFS curve fitting analysis results of the Ru6 / KBO catalyst prepared in this embodiment. It can be seen that the coordination number of Ru-Ru in the prepared catalyst Ru6 / KBO is 2.7, which is a planar structure.

[0051] Table 1. EXAFS curve fitting analysis results of Ru6 / KBO catalyst

[0052]

[0053] Path: Coordinating element, indicating the types of coordinating atoms in the sample that bond with the central element; CN: Coordination number, indicating the types of coordinating atoms in the sample that bond with the central element; R: Bond length, indicating the average distance between coordinating atoms; σ 2 : Debye-Waller factor, representing the degree of disorder in the atomic arrangement of the sample; ΔE: internal potential correction value, representing the magnitude of energy change during the fitting process; R-factor: goodness of fit, used to evaluate the accuracy of the fitting results.

[0054] Figure 5 This is a schematic diagram of the structure of the Ru6 / KBO catalyst prepared in this embodiment.

[0055] Example 2

[0056] The other conditions and operations are the same as in Example 1, except that in the rapid heating and cooling calcination reduction step, the calcination temperature is changed to 350°C and the time is changed to 100s.

[0057] Example 3

[0058] The other conditions and operations are the same as in Example 1, except that in the rapid heating and cooling calcination reduction step, the calcination temperature is changed to 500°C and the time is changed to 120s.

[0059] Example 4

[0060] Other conditions and operations are the same as in Example 1, except for the precursor cluster [NBu4]2[Ru6C(CO). 16 The amount of Ru added was 2 mg, and the loading of Ru in the composite catalyst prepared in this example was 0.594 wt% as determined by inductively coupled plasma atomic emission spectrometry (ICP).

[0061] Example 5

[0062] Other conditions and operations are the same as in Example 1, except for the precursor cluster [NBu4]2[Ru6C(CO). 16 The amount of Ru added was 7 mg, and the loading of Ru in the composite catalyst prepared in this example was 2.074 wt% as determined by inductively coupled plasma atomic emission spectrometry (ICP).

[0063] Comparative Example 1

[0064] Other conditions and operations were the same as in Example 1, except that the calcination temperature was changed to 300°C in the rapid heating and cooling calcination reduction step. The ligands were not completely removed, resulting in poor catalytic performance.

[0065] Comparative Example 2

[0066] The other conditions and operations are the same as in Example 1, except that the calcination temperature is changed to 550°C in the rapid heating and cooling calcination reduction step.

[0067] Figure 7 The image shows a TEM image of the catalyst obtained in Comparative Example 2. It can be seen that black spots are distributed on the support, indicating that the Ru6 clusters agglomerated due to excessively high calcination temperature.

[0068] Comparative Example 3

[0069] The other conditions and operations are the same as in Example 1, except that the calcination holding time in the rapid heating and cooling calcination reduction is changed from 120s to 60s.

[0070] Comparative Example 4

[0071] The other conditions and operations are the same as in Example 1, except that the calcination holding time in the rapid heating and cooling calcination reduction is changed from 120s to 150s. Figure 8 The image shows a TEM image of the catalyst obtained in Comparative Example 4. It can be seen that many black spots are also distributed on the support, indicating that excessive calcination time can also lead to the aggregation of Ru6 clusters.

[0072] Comparative Example 5

[0073] Other conditions and operations are the same as in Example 1, except for the precursor cluster [NBu4]2[Ru6C(CO). 16 The amount of Ru added was 1 mg, and the loading of Ru in the composite catalyst prepared in this example was 0.295 wt% as determined by inductively coupled plasma atomic emission spectrometry (ICP).

[0074] Comparative Example 6

[0075] The other conditions and procedures were the same as in Example 1, except that a black product [NBu4]2[Ru6C(CO) was obtained. 16 ] / KBO, without subsequent calcination.

[0076] Comparative Example 7

[0077] 50 mg of OCNT was dispersed in 20 mL of methanol and sonicated for 60 min. Using RuCl3·3H2O as the Ru source, 250 μL of aqueous solution containing 0.2 mg of RuCl3·3H2O (the pH of the solution was adjusted to 1 with hydrochloric acid) was added dropwise to the OCNT dispersion while stirring. After stirring magnetically at room temperature for 24 h, the solid product was collected by centrifugation, washed twice with methanol solution, and then dried in vacuum freeze-drying at 30 °C. After drying, the powder was heated in a Joule furnace at 400 °C for 120 s under a flowing Ar atmosphere to obtain the Ru SAs / OCNT catalyst as a control catalyst. Figure 9 This is an aberration-corrected transmission electron microscope (AC-TEM) image of the single-atom catalyst prepared in Comparative Example 7. The image shows that Ru single atoms are uniformly dispersed on the support without aggregation.

[0078] Comparative Example 8

[0079] A commercial Pt / C with a mass fraction of 20 wt% was used as a comparative catalyst for this catalyst.

[0080] Comparative Example 9

[0081] A commercial Ru / C with a mass fraction of 5 wt% was used as a control catalyst for this catalyst.

[0082] Comparative Example 10

[0083] Similar to Example 1, except that step S1 is omitted and the mass of Ketjen black oxide in step S2 is replaced with Ketjen black (KB). It was found that the solution after loading was darker in color and the amount of Ru that could be loaded was extremely low.

[0084] Comparative Example 11

[0085] Take the above-mentioned black product and place it on carbon cloth, then heat it in a tube furnace at 5°C for 5 minutes. -1 The temperature was increased to 400℃ at a heating rate, calcined in a N2 atmosphere for 120s, and then naturally cooled to room temperature to obtain an alkaline water electrolysis hydrogen evolution supported Ru6 cluster catalyst.

[0086] Application examples

[0087] The catalyst performance of the above examples and comparative examples was tested in a standard three-electrode system, with a carbon rod as the counter electrode, a saturated calomel electrode (SCE) as the reference electrode, and the prepared Ru6 / KBO (dropped onto hydrophilic carbon paper) as the working electrode. All data were calibrated relative to the standard hydrogen electrode (RHE) potential, and the electrolyte test results were 95% IR corrected to reduce the impedance of the solution during the test.

[0088] The calibration formula is:

[0089] E (RHE) =E (SCE) +0.0591*pH+0.24-0.95*I*R

[0090] Among them, E (RHE) The potential of the standard hydrogen electrode;

[0091] E (SCE) The potential of a saturated calomel electrode;

[0092] I: Current density generated during the test;

[0093] R: Impedance during the test.

[0094] Overpotential η 10 At a current density of 10 mA / cm -2 At that time, the magnitude of the overpotential.

[0095] Table 2 Catalyst Performance Indicators

[0096]

[0097] Table 2 shows that the catalyst prepared using the method in Example 1 exhibits excellent HER performance and stability at room temperature under alkaline conditions. While Example 5 also demonstrates excellent performance under the same conditions, the addition of the noble metal Ru results in a slightly higher cost. Comparative Examples 1 and 2 verify the effect of calcination temperature on catalyst activity. Too low a temperature (Comparative Example 1) leads to incomplete ligand removal and poor HER activity; too high a temperature (Comparative Example 2) causes cluster aggregation. Comparative Examples 3 and 4 demonstrate the effect of calcination time. In Comparative Example 3, too short a calcination time results in incomplete ligand removal and poor HER activity; in Comparative Example 4, too long a calcination time causes cluster aggregation. Comparative Example 5 adds... Insufficient Ru content results in fewer reactive sites and poor HER reaction activity; Comparative Example 6 shows poor activity due to the lack of ligand removal; Comparative Example 7 is a single-atom comparison with poor activity; Comparative Examples 8 and 9 are commercial catalysts, and the catalyst prepared in this experiment has better activity and stability than commercial catalysts; Comparative Example 10 shows the effect of the support on catalyst activity. When Ketjen black is used directly as a support without acid treatment, the incomplete loading results in extremely low Ru loading and extremely poor activity; Comparative Example 11 shows the effect of the heating device. When using a common tube furnace device, the nature of the device itself causes the catalyst to be exposed to high temperatures for a long time, leading to Ru6 cluster aggregation.

[0098] Figure 10 LSV diagrams of the hydrogen evolution reaction in 1M KOH solution for the catalysts prepared in Examples 1, 7, 8, 9, and 10; from Figure 10 It can be seen from this that at 10mAcm -2At a given current density, the overpotential of Ru6 / OCNT is 25.6 mV, which is close to that of the Pt / C catalyst (26.1 mV) and superior to that of the Ru / C catalyst (50.6 mV) and the RuSAs / OCNT catalyst (171.9 mV). However, the Pt / C catalyst has a Pt loading of 20 wt%, which is costly. This patent achieves performance close to that of a commercial 20 wt% Pt / C catalyst with an extremely low Ru loading. Moreover, the catalyst of this invention is more stable at high current densities and has the potential for commercial application.

[0099] Figure 11 The graphs show the stability of the catalysts prepared in Examples 1, 8, and 9 in 1M KOH solution. Figure 11 As can be seen from the data, the Ru6 / KBO catalyst, when subjected to an application of 250 mAcm, exhibits [results in] ...the following]. -2 The voltage remained almost unchanged after 24 hours of electrolysis at the specified current density, which is superior to commercial Ru / C catalysts and comparable to commercial Pt / C catalysts.

[0100] This invention is the first to discover that catalysts prepared from Ru6 clusters with a precise number of atoms exhibit significantly enhanced catalytic activity, demonstrating excellent catalytic performance for hydrogen evolution reaction (HER). In contrast, single-atom Ruthenium catalysts do not achieve the same superior catalytic activity. This is likely because the unique structure of Ru6 clusters optimizes the free energy of the hydrogen adsorption step at the active site, promoting HER kinetics under alkaline conditions and resulting in catalytic activity and lifetime comparable to commercial electrodes. In contrast, single-atom Ruthenium catalysts, due to their single active site, struggle to modulate the binding mode of adsorbed intermediates during the reaction, lacking synergistic effects. In some reactions, such as the alkaline hydrogen evolution reaction, their catalytic activity is inferior to that of Ru6 clusters.

Claims

1. A Ru6 cluster catalyst supported for alkaline water electrolysis and hydrogen evolution, characterized in that, In the catalyst, precisely six Ru atoms are supported as a cluster on a Ketjen black oxide support, with a Ru-Ru coordination number of 2.5-2.7, exhibiting a planar structure, and the Ru loading is 0.5-2.4 wt%. The preparation method of the supported Ru6 cluster catalyst includes the following steps: (S1) Weigh out Ketjen black, treat it with nitric acid, wash it, and dry it to obtain Ketjen black oxide; (S2) ultrasonic dispersion of a Ru source [NBu4]2[Ru6C(CO) 16 ] in an organic solvent, slow addition to a solution uniformly dispersed with Ketjen black, stirring, centrifugal washing, drying, to obtain a precursor, the precursor is rapidly heated and calcined in a inert gas atmosphere with a joule furnace, the calcination temperature is 350-500℃, the calcination time is 100-120 s, and then natural cooling to obtain an atomic number accurate Ru6 cluster catalyst loaded on Ketjen black.

2. The supported Ru6 cluster catalyst according to claim 1, characterized in that, The Ru loading is 0.5-2.4 wt%.

3. The supported Ru6 cluster catalyst according to claim 1, characterized in that, The Ru loading is 1.4-2.1 wt%.

4. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S1), the concentration of nitric acid is 5-6 mol·L -1 The mass-volume ratio of Ketjen black and nitric acid is 1 g: 100-150 mL, and the nitric acid treatment is performed at 60-80 °C for 20-30 h.

5. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S2), the organic solvent is one of dichloromethane and tetrahydrofuran; the amount of Ru source and organic solvent used is such that the concentration of Ru source in the organic solvent is 0.1-0.5 mg / mL.

6. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S2), the concentration of Ketjen black oxide in the uniformly dispersed solution is 1-5 mg / mL.

7. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S2), the stirring is carried out at room temperature for 9-12 hours.

8. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S2), the inert gas is a nitrogen atmosphere, and the calcination temperature is 400-500 ℃.

9. The supported Ru6 cluster catalyst according to claim 1, characterized in that, In step (S2), the rapid heating is achieved by using a Joule furnace to rapidly heat the temperature to the target temperature within 1-2 seconds.

10. Use of the supported Ru6 cluster catalyst according to any one of claims 1-9 for electrocatalytic HER under alkaline conditions.

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