Highly conductive anti-start-stop alkaline electrolytic water cathode ruthenium-based catalyst and preparation method thereof
By loading ruthenium nanoparticles onto the surface of titanium dioxide and combining them with conductive carbon black, the oxidation, dissolution, and conductivity issues of ruthenium-based catalysts under start-up and shutdown conditions were solved, and a highly conductive, start-up- and shutdown-resistant alkaline water electrolysis cathode catalyst was prepared, which is suitable for AEM water electrolysis technology under renewable energy fluctuations.
Patent Information
- Application Number
- CN202611501514.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-24
- Publication Date
- 2026-11-03
AI Technical Summary
Existing alkaline water electrolysis ruthenium-based catalysts are easily oxidized and dissolved under frequent start-stop and reverse current conditions. Pure titanium dioxide supports have poor conductivity, resulting in severe polarization under high current. Furthermore, the preparation process of traditional composite catalysts is complex and difficult to scale up industrially.
Titanium dioxide was used as a sacrificial electron library for ruthenium, and a composite carrier was constructed by combining it with conductive carbon black. Ruthenium nanoparticles were uniformly loaded on the surface of titanium dioxide through ultrasonic dispersion, ball milling and mixing and annealing treatment to form a highly conductive composite catalyst and enhance its start-stop stability.
It achieves high conductivity and antioxidant solubility of the catalyst under frequent start-stop and high current density conditions, reduces operating cell voltage, extends service life, and is suitable for AEM water electrolysis technology under renewable energy fluctuations.
Smart Images
Figure CN123027612A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials synthesis and electrocatalysis technology, specifically relating to a ruthenium-based catalyst for a highly conductive, start-stop resistant alkaline water electrolysis cathode and its preparation method. Background Technology
[0002] With the continuous expansion of renewable energy power generation from wind and solar power, utilizing renewable energy to drive alkaline water electrolysis via anion exchange membranes (AEM) to produce green hydrogen has become one of the important technological routes for large-scale hydrogen production. In the AEM water electrolysis system, the hydrogen evolution reaction (HER) catalyst is the key component determining the electrolysis efficiency and the cost of hydrogen production. Ruthenium (Ru) has excellent HER activity close to that of platinum (Pt), and its cost is relatively low with relatively less resource constraints, therefore it is considered an important low-cost catalyst candidate to replace Pt.
[0003] However, renewable energy power generation is characterized by significant intermittency and volatility, causing water electrolysis systems to frequently experience unsteady operating conditions such as start-up, shutdown, load changes, and power outages. During start-up, shutdown, or power outages, destructive reverse currents can easily be generated inside the electrolyzer, causing the cathode to be momentarily subjected to a strong high-potential impact from the anode. Under abnormally high potentials, Ru readily loses electrons and is deeply oxidized into soluble high-valence species (such as RuO4). 2- This causes a large amount of active sites to dissolve and be lost, which in turn leads to the decay of catalyst activity and a shortening of device life, severely restricting the long-term stable operation of ruthenium-based catalysts in industrial electrolyzers.
[0004] To suppress the oxidative dissolution of Ru, introducing TiO2, which exhibits high stability under strong oxidation potentials, as a catalyst support is considered an effective strategy. TiO2 can act as a "sacrificial electron pool" during high-potential shocks, preferentially consuming electrons or buffering valence states to prevent Ru from losing electrons and being oxidized, thereby effectively suppressing Ru dissolution. However, existing research on titanium dioxide-supported ruthenium catalysts mainly focuses on conventional hydrogen evolution activity, lacking specific designs for anti-start-stop operations under frequent start-stop and reverse current conditions. Furthermore, pure oxide supports have poor intrinsic conductivity, resulting in high resistance at high current densities, which can easily lead to high cell voltages. In addition, existing synthetic routes for composite electrocatalysts often suffer from cumbersome steps, difficulty in process control, and poor industrial scale-up consistency, making it difficult to simultaneously achieve high conductivity, anti-start-stop stability, and large-scale preparation requirements.
[0005] Therefore, there is an urgent need to develop an alkaline water electrolysis cathode ruthenium-based catalyst that combines excellent hydrogen evolution activity, high conductivity, and strong start-stop stability, and whose preparation process is simple, the reaction conditions are mild, the reproducibility is good, and it is easy to scale up to an industrial scale, so as to meet the practical application needs of AEM water electrolysis technology in the context of renewable energy fluctuation hydrogen production. Summary of the Invention
[0006] The purpose of this invention is to overcome the technical defects of existing alkaline water electrolysis ruthenium-based catalysts, such as the easy oxidation and dissolution of Ru under frequent start-stop and reverse current conditions, the poor intrinsic conductivity of pure titanium dioxide support leading to severe polarization under high current, and the complex preparation process and difficulty in industrial scale-up of traditional composite catalysts. The invention provides a highly conductive alkaline water electrolysis cathode ruthenium-based catalyst with start-stop resistance, its preparation method and application.
[0007] Specifically, this invention aims to provide a simple, mild, reproducible, and easily scaled-up ruthenium-based catalyst preparation method. The catalyst prepared by this method should possess excellent hydrogen evolution activity, good conductivity and transport capability, and strong resistance to reverse current oxidation and dissolution. It should also have low operating cell voltage and long service life under fluctuating start-stop conditions and high current density conditions in alkaline water electrolysis, thereby meeting the application requirements of anion exchange membrane (AEM) water electrolysis technology in renewable energy fluctuating hydrogen production scenarios.
[0008] To achieve its objectives, the present invention employs the following technical solution: This invention provides a method for preparing a ruthenium-based catalyst for a highly conductive, start-stop resistant alkaline water electrolysis cathode, comprising the following steps: (1) Add titanium dioxide to water, disperse it evenly by ultrasonication and adjust the pH of the solution to alkaline, then add a ruthenium source to obtain a reaction mixture; heat the reaction mixture in a constant temperature oil bath under nitrogen atmosphere protection; after heating, collect the reaction product and wash it by centrifugation multiple times with a mixture of deionized water and ethanol, and then dry it. (2) Grind the dried product from step (1) and then mix it with conductive carbon black by high-speed ball milling to obtain a mixed powder. Transfer the mixed powder to a quartz boat and anneal it in an H2 atmosphere. After the reaction system cools to room temperature, the target product is obtained.
[0009] Preferably, in step (1): the ultrasonic dispersion power is 50-100 W, and the ultrasonic time is 20-100 min. The pH is adjusted to 8.0, and the pH adjuster is one or more of ammonia, sodium hydroxide, and sodium carbonate. The ruthenium source includes one or more of ruthenium trichloride, ruthenium acetylacetonate, ruthenium nitrate, and hexaammineruthenium chloride, and the molar ratio of the ruthenium source (calculated as Ru) to titanium dioxide is 5:95. The constant temperature oil bath heating temperature is 50-100℃, and the heating time is 5-15 h.
[0010] Preferably, in step (2): the conductive carbon black includes one or more of KJ600, XC72, and KJ300; the mass percentage of the conductive carbon black to the product dried in step (1) is (0%–50%):(100%–50%). The high-speed ball mill operates at a speed of 200–800 rpm for 0.5–6 h. The H2 atmosphere is pure H2, or a mixture of H2 with one or more of Ar and N2; the annealing temperature is 300–700℃, the heating rate is 5–10℃ / min, and the treatment time is 0.5–5 h.
[0011] This invention also provides a highly conductive, start-stop resistant alkaline water electrolysis cathode ruthenium-based catalyst prepared by the above-described method. The catalyst comprises ruthenium nanoparticles, titanium dioxide, and conductive carbon black; the ruthenium nanoparticles are supported on the surface of titanium dioxide, and the titanium dioxide and conductive carbon black form a composite support.
[0012] The present invention also provides the application of the above-mentioned catalyst in the hydrogen evolution reaction at the cathode of alkaline water electrolysis, especially in the application of anion exchange membrane (AEM) alkaline water electrolysis devices, particularly in the application under frequent start-stop and / or reverse current conditions.
[0013] Compared with existing technologies, this invention, based on the synergistic effect between the titanium dioxide sacrificial electron pool, metal-carrier interaction, and carbon black conductive network, has the following beneficial effects: (1) This invention provides a method for preparing a ruthenium-based catalyst for a highly conductive alkaline water electrolysis cathode that is resistant to start-stop. This method has a short process flow, is easy to operate, has mild reaction conditions, good repeatability, and is easy to scale up on an industrial scale.
[0014] (2) In this invention, ruthenium is loaded onto the surface of titanium dioxide and combined with conductive carbon black, so that the ruthenium nanoparticles are uniformly dispersed on the composite support and the utilization rate of active sites is high. The strong metal-support interaction between ruthenium and titanium dioxide helps to stabilize the ruthenium nanoparticles and improve their dispersibility, so that the resulting catalyst exhibits good catalytic activity in the hydrogen evolution reaction of the cathode in alkaline water electrolysis.
[0015] (3) Titanium dioxide can act as a sacrificial electron pool under high potential impact of reverse current, preferentially consuming electrons or buffering valence states, thereby inhibiting ruthenium from losing electrons and being deeply oxidized into soluble high-valence species, reducing the dissolution and loss of ruthenium active sites, and making the catalyst have good stability under frequent start-stop and reverse current conditions.
[0016] (4) The combination of conductive carbon black and titanium dioxide can construct a three-dimensional electron transport network, which can improve the problem of poor intrinsic conductivity of pure titanium dioxide support, reduce ohmic polarization and operating cell voltage under high current density, and improve the conductive transport capability of the catalyst.
[0017] (5) By adjusting the composite ratio of conductive carbon black, a balance can be achieved between catalytic activity and anti-start-stop stability. Under the preferred ratio, the resulting composite catalyst can take into account high hydrogen evolution activity, good conductivity and good anti-start-stop durability, and its comprehensive performance is better than that of single titanium dioxide supported ruthenium catalyst or pure carbon black supported ruthenium catalyst.
[0018] (6) The catalyst obtained by the present invention is suitable for the hydrogen evolution reaction at the cathode of alkaline water electrolysis, and is especially suitable for anion exchange membrane (AEM) water electrolysis devices with frequent start-stop and reverse current conditions. It has good prospects for industrial application in the scenario of hydrogen production under renewable energy fluctuations. Attached Figure Description
[0019] Figure 1 These are TEM images of the titanium dioxide-supported ruthenium nanomaterials prepared in Example 1 of this invention. Figure 2 The figures show the overall performance test results of the catalysts obtained in Examples 1-4 and Comparative Example 1 of this invention applied to anion exchange membrane (AEM) water electrolysis devices. Figure 3 This is a graph showing the operational stability of the catalyst obtained in Example 1 of the present invention under repeated start-stop conditions; Figure 4 This is a graph showing the operational stability of the catalyst obtained in Example 2 of the present invention under repeated start-stop conditions; Figure 5 This is a graph showing the operational stability of the catalyst obtained in Example 3 of the present invention under repeated start-stop conditions; Figure 6 This is a graph showing the operational stability of the catalyst obtained in Example 4 of the present invention under repeated start-stop conditions; Figure 7 This is a graph showing the operational stability of the catalyst obtained in Comparative Example 1 of the present invention under repeated start-stop conditions; Detailed Implementation
[0020] The following detailed description, with reference to embodiments, illustrates the ruthenium-based catalyst for the highly conductive, start-stop resistant alkaline water electrolysis cathode provided by the present invention and its application in AEM electrolysis devices. The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.
[0021] Example 1 In this embodiment, titanium dioxide-supported ruthenium nanomaterials (Ru / TiO2) were synthesized according to the following steps. (1) Titanium dioxide was added to water and ultrasonically dispersed at 80 W for 60 min. Sodium carbonate was added to adjust the pH of the solution to 8.0, and then ruthenium acetylacetone was added to obtain a reaction mixture. The molar ratio of ruthenium acetylacetone to titanium dioxide was 5:95 (calculated as Ru). The reaction mixture was then heated in an oil bath under a nitrogen atmosphere at 80 °C for 10 h. After heating, the reaction product was collected and washed multiple times by centrifugation with a mixture of deionized water and ethanol, and then dried.
[0022] (2) Grind the solid powder obtained from drying in step (1) for 30 min, then place it in a quartz boat and put it into a tube furnace for annealing. First, pre-purge with a 5% H2 / 95% Ar mixed gas for 20 min to remove air from the tube, then continue to purge with the above mixed gas, control the heating rate at 5℃ / min, heat to 500℃ and then anneal at a constant temperature for 2 h. After annealing, allow it to cool naturally to room temperature, collect the product, and record the obtained catalyst as Ru / TiO2.
[0023] like Figure 1 As shown in the figure, TEM characterization revealed that Ru was uniformly coated on the TiO2 surface in the obtained product, with no excess Ru particles scattered.
[0024] Example 2 In this embodiment, a titanium dioxide-supported ruthenium-carbon composite catalyst (Ru / TiO2-C15%) was synthesized according to the following steps. (1) Titanium dioxide was added to water and ultrasonically dispersed at 80 W for 60 min. Sodium carbonate was added to adjust the pH of the solution to 8.0, and then ruthenium acetylacetone was added to obtain a reaction mixture. The molar ratio of ruthenium acetylacetone to titanium dioxide was 5:95 (calculated as Ru). The reaction mixture was then heated in an oil bath under a nitrogen atmosphere at 80 °C for 10 h. After heating, the reaction product was collected and washed multiple times by centrifugation with a mixture of deionized water and ethanol, and then dried.
[0025] (2) Grind the solid powder obtained from drying in step (1) for 30 min. Then, according to the mass percentage of conductive carbon black and the product dried in step (1) being 15%:85%, put it together with KJ300 conductive carbon black into a ball mill. The total amount of raw materials and the mass ratio of the ball milling beads are 1:15, and the mass ratio of 3 mm and 5 mm ball milling beads is 1:1. Ball mill at 800 rpm for 3 h. Take out the ball-milled product and place it in a quartz boat, and put it into a tube furnace for annealing. First, pre-introduce 5% H2 / 95% Ar mixed gas for 20 min to remove air from the tube. Then continue to introduce the above mixed gas, control the heating rate to be 5℃ / min, and anneal at a constant temperature for 2 h after heating to 500℃. After annealing, let it cool naturally to room temperature and collect the product. The obtained catalyst is recorded as Ru / TiO2-C15%.
[0026] Example 3 The mass percentage of conductive carbon black and the product after drying in step (1) in Example 2 was adjusted to 25%:75%, and the remaining methods and conditions were completely consistent with those in Example 2. The resulting catalyst was denoted as Ru / TiO2-C25.
[0027] Example 4 The mass percentage of conductive carbon black in Example 2 and the product after drying in step (1) was adjusted to 50:50. All other methods and conditions were completely consistent with those in Example 2. The resulting catalyst was denoted as Ru / TiO2-C50.
[0028] Comparative Example 1 The TiO2 support in Example 1 was replaced with KJ300 carbon black support, the molar ratio of ruthenium source to support remained unchanged, and the rest of the methods and conditions were completely consistent with those in Example 1. The resulting catalyst was denoted as Ru / C.
[0029] Membrane electrode fabrication and device assembly: A two-electrode system was used to construct an anion exchange membrane (AEM) water electrolysis test device. 30 mg of the catalyst active material was weighed and dispersed in a mixture of 1 mL deionized water, 3 mL isopropanol, and 18 mL polytetrafluoroethylene (PTFE). The mixture was ultrasonically dispersed for 30 min to obtain a uniformly dispersed catalyst slurry. The slurry was then uniformly sprayed onto the surface of the anion exchange membrane using an ultrasonic spraying process, with an effective spraying area of 2 cm × 2 cm and a catalyst loading controlled at 1 mg / cm². 2 .
[0030] NiFe-LDH prepared by hydrothermal method was selected as the anode catalyst (preparation method reference: Zhao J, Zhang Y, Ye Y, et al. Remote Iron dynamics of NiFe (oxy) hydroxides toward robustactive sites in water oxidation[J]. Nature Communications, 2025, 16(1):5601.). The anode used nickel foam as a porous transport layer, and the cathode used hydrophilic carbon paper as a porous transport layer. A 50 μm thick anion exchange membrane was selected. A serpentine flow channel was arranged inside the device to complete the overall assembly and obtain AEM water electrolysis test device A for activity testing.
[0031] Commercial nickel felt was selected as the anode catalyst material, nickel foam was used as the porous transport layer for the anode, and hydrophilic carbon paper was used as the porous transport layer for the cathode. An anion exchange membrane with a thickness of 80 μm was selected, and a serpentine flow channel was arranged inside the device. After the overall assembly was completed, the AEM water electrolysis test device B was obtained and used for stability testing.
[0032] Performance Tests and Results: Figure 2 The figures show the overall performance test results of the catalysts obtained in Examples 1-4 and Comparative Example 1 of this invention applied to the AEM water electrolysis device. The test results show that when Ru / TiO2 and KJ300 are ball-milled and mixed in a certain proportion as a cathode catalyst, the performance is significantly improved compared to Ru / TiO2 and is superior to pure Ru / C.
[0033] Figures 3 to 7 The figures show comparative test curves of the long-term stability of the AEM water electrolysis device B assembled with the catalysts obtained in Examples 1-4 and Comparative Example 1 under repeated start-stop conditions. All tests were conducted under the same conditions: electrolyte was 1 MkOH, test temperature was 60°C, and the start-stop cycle condition was 1 A cm⁻¹. -2 Run at constant current for 5 minutes, then let stand for 5 minutes after power off, and repeat the cycle for 10 minutes.
[0034] Depend on Figure 3 It can be seen that Ru / TiO2 has poor initial activity, but good resistance to start-stop, with a decay rate of 5 mV / cycle after 20 cycles.
[0035] Depend on Figure 4 It can be seen that Ru / TiO2-C15% has significantly improved initial activity, good anti-start-stop effect, and a decay rate of 22.6 mV / cycle after 20 cycles.
[0036] Depend on Figure 5It can be seen that the anti-start-stop effect of Ru / TiO2-C25% deteriorates, with a decay rate of 29.3 mV / cycle after 20 cycles.
[0037] Depend on Figure 6 It can be seen that Ru / TiO2-C50% has a worse start-stop resistance, with a decay rate of 31.4 mV / cycle after 20 cycles.
[0038] Depend on Figure 7 It can be seen that the anti-start-stop effect of Ru / C has a decay rate of 26.3mV / cycle after 20 cycles, which is worse than that of Ru / TiO2-C15.
[0039] comprehensive Figures 2 to 7 The results show that as the proportion of conductive carbon black increases, the initial hydrogen evolution activity of the Ru / TiO2-C composite catalyst is improved, but the start-stop stability gradually decreases. The Ru / TiO2-C 15% catalyst maintains high hydrogen evolution activity while having good start-stop stability, making it the optimal ratio that balances catalytic activity and start-stop durability.
[0040] In summary, the Ru / TiO2-C composite material prepared by this invention, when applied to an AEM water electrolysis system, exhibits both excellent electrocatalytic activity and operational stability under suitable carbon black mixing ratios, making it suitable for practical applications of intermittent renewable energy electrolysis hydrogen production.
[0041] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications still fall within the protection scope of the technical solution and claims of the present invention.
Claims
1. A method for preparing a ruthenium-based catalyst for a highly conductive, start-stop resistant alkaline water electrolysis cathode, characterized in that, Includes the following steps: (1) Add titanium dioxide to water, disperse it evenly by ultrasonication and adjust the pH of the solution to alkaline, then add a ruthenium source to obtain a reaction mixture; heat the reaction mixture in a constant temperature oil bath under nitrogen atmosphere protection; after heating, collect the reaction product and wash it by centrifugation multiple times with a mixture of deionized water and ethanol, and then dry it. (2) Grind the dried product from step (1) and mix it with conductive carbon black by high-speed ball milling to obtain a mixed powder; transfer the mixed powder to a quartz boat and anneal it in an H2 atmosphere. After the reaction system cools to room temperature, the target product is obtained.
2. The preparation method according to claim 1, characterized in that, In step (1), the ultrasonic dispersion power is 50-100 W and the ultrasonic time is 20-100 min.
3. The preparation method according to claim 1, characterized in that, In step (1), the pH is adjusted to 8.0, and the pH adjuster is selected from one or more of ammonia, sodium hydroxide, and sodium carbonate.
4. The preparation method according to claim 1, characterized in that, In step (1), the ruthenium source includes one or more of ruthenium trichloride, ruthenium acetylacetonate, ruthenium nitrate, and hexaammine ruthenium chloride. The molar ratio of the ruthenium source to titanium dioxide is 5:95, calculated as Ru.
5. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the constant temperature oil bath is 50-100℃ and the heating time is 5-15h.
6. The preparation method according to claim 1, characterized in that, In step (2), the mass percentage of the conductive carbon black to the product dried in step (1) is (0%~50%):(100%~50%).
7. The preparation method according to claim 1, characterized in that, In step (2), the high-speed ball mill rotates at a speed of 200 to 800 rpm and the milling time is 0.5 to 6 h.
8. The preparation method according to claim 1, characterized in that, In step (2), the H2 atmosphere is pure H2, or a mixture of H2 with one or more of Ar and N2, and the annealing temperature of the annealing treatment is 300-700℃, the heating rate is 5-10℃ / min, and the treatment time is 0.5-5h.
9. A ruthenium-based catalyst for a highly conductive, start-stop resistant alkaline water electrolysis cathode, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.
10. The application of the highly conductive, start-stop resistant ruthenium-based catalyst for alkaline water electrolysis cathode as described in claim 9 in the hydrogen evolution reaction at the alkaline water electrolysis cathode.