Nb2O5 microflower-loaded Ru catalyst based on Lewis acid activation mechanism as well as preparation method and application of Nb2O5 microflower-loaded Ru catalyst
By preparing Nb2O5 micron flower-loaded Ru catalyst based on the Lewis acid activation mechanism, the problems of instability and insufficient active sites of RuO2/Nb2O5 catalyst in alkaline seawater HER were solved, and efficient and stable hydrogen production performance by electrolysis of seawater was achieved.
Patent Information
- Application Number
- CN202511010177.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-10-28
AI Technical Summary
Existing RuO2/Nb2O5 catalysts exhibit instability, lack of efficient water dissociation sites, and susceptibility to chloride ion poisoning in alkaline seawater HER, resulting in poor catalytic performance.
A method combining hydrothermal loading and high-temperature calcination was used to prepare Nb2O5 micro-flower-loaded Ru catalyst based on Lewis acid activation mechanism. Nb5+ polarized water molecules were used to promote water dissociation, and highly dispersed active sites were exposed through the micro-flower structure, thereby enhancing the catalyst's resistance to chlorine corrosion and reaction efficiency.
It achieves high catalytic activity and long-term stability in alkaline seawater, low overpotential, large electrochemically active surface area, and low Ru loading, which significantly improves the electrochemical performance and stability of the catalyst and is suitable for hydrogen production by electrolysis of seawater.
Smart Images
Figure CN120844146A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electrode material preparation technology, and in particular to a Nb2O5 micron-flower-supported Ru catalyst based on Lewis acid activation mechanism, its preparation method and application. Background Technology
[0002] With the global energy crisis and environmental degradation becoming increasingly severe, the development of clean and renewable resources has become an urgent priority. Hydrogen energy, due to its high energy density and zero-pollution combustion products, is considered the most promising green energy carrier. Compared to "grey hydrogen" produced from traditional fossil fuel reforming, hydrogen production technology using renewable energy-driven seawater electrolysis can achieve truly "green hydrogen" production.
[0003] Global freshwater resources account for only 2.5% of the Earth's total water volume, while seawater accounts for a staggering 96.5%. This makes seawater electrolysis for hydrogen production a key breakthrough in addressing the water resource constraints of future large-scale green hydrogen production. However, the cathode process for seawater electrolysis for hydrogen production faces far more severe challenges than that for freshwater electrolysis. The core problem on the cathode side of seawater electrolysis for hydrogen production lies in the dual inhibition of the hydrogen evolution reaction (HER) by the corrosive effect of high-concentration chloride ions and the proton-poor environment. On the one hand, chloride ions strongly adsorb onto the catalyst surface, forming stable metal-chlorine bonds with active sites. This not only directly occupies hydrogen adsorption sites but may also trigger the electrochemical dissolution of the metal active components. On the other hand, the weak alkalinity of seawater (pH≈8) results in extremely low proton concentrations, forcing the HER to rely on the slower-kinetic dissociation pathway of water molecules.
[0004] Commercial platinum-carbon catalysts still exhibit unsatisfactory catalytic performance in high-salinity, proton-depleted seawater environments, and are also expensive. Therefore, the development of novel catalysts with resistance to chlorine corrosion, high activity, and high stability is urgently needed. Ruthenium (Ru), due to its hydrogen adsorption free energy similar to that of Pt and its lower cost (approximately 1 / 5 that of Pt), is expected to replace Pt as the next generation of HER catalysts. In the alkaline seawater HER field, metallic Ru exhibits superior catalytic performance compared to ruthenium dioxide (RuO2). This advantage mainly stems from the perfect compatibility of its unique electronic structure and surface chemistry with the HER reaction mechanism. RuO2 is readily reduced to Ru in alkaline HER, and the RuO2 surface is unfavorable for H* adsorption. The electronic structure of metallic Ru is better suited to the ΔG H* optimization of HER.
[0005] Existing RuO2 / Nb2O5 catalysts are designed for acidic OER, which rely on oxygen vacancies to promote oxygen release. However, this design has the following problems in alkaline seawater HER: (1) RuO2 is unstable in an alkaline reducing environment and is easily converted into metallic Ru and agglomerates; (2) It lacks efficient water dissociation sites, and the RuO2 surface is not conducive to H* adsorption, resulting in slow alkaline HER kinetics; (3) Cl in seawater- It poisons the active sites and reduces stability.
[0006] Therefore, developing ruthenium-based catalysts with high activity, long lifespan, and resistance to seawater poisoning is crucial to overcoming the bottlenecks in seawater electrolysis for hydrogen production. Recent research indicates that strategies such as constructing strong metal-support interactions (SMSI) and designing hierarchical porous structures can significantly improve the stability and corrosion resistance of Ru catalysts. Summary of the Invention
[0007] In view of this, this application provides a Nb₂O₅ micro-flower-supported Ru catalyst based on a Lewis acid activation mechanism, its preparation method, and its application. On the one hand, it utilizes Nb₂O₅... 5+ Polarized water molecules promote water dissociation, accelerating the rate-determining step of the hydrogen evolution reaction (HER) and providing protons for the reaction. The surface OH* further resists chloride ions in seawater. On the other hand, the micron-flower structure exposes more highly dispersed active sites, accelerating reaction efficiency while avoiding bubble blockage. This application employs a simple strategy combining hydrothermal loading and high-temperature calcination to prepare a niobium pentoxide-supported ruthenium catalyst, which is then applied to the hydrogen evolution reaction in seawater electrolysis. The preparation method presented in this application shows promise for electrocatalysis and is of significant research value in promoting the industrialization of ruthenium-based catalysts in water electrolysis, effectively overcoming the shortcomings of existing technologies.
[0008] The first aspect of this application provides a method for preparing a Ru catalyst supported on Nb₂O₅ micro-flowers based on a Lewis acid activation mechanism, comprising the following steps:
[0009] (1) Niobium oxalate and ammonium carbonate are dissolved in water and stirred vigorously to obtain a mixture A. The mixture A is subjected to a hydrothermal reaction. After the reaction is completed, it is washed, dried and then calcined to obtain niobium pentoxide.
[0010] (2) Niobium pentoxide, ruthenium trichloride and water are mixed and stirred vigorously to obtain mixture B. Mixture B is subjected to hydrothermal reaction. After the reaction is completed, it is washed, dried and then annealed to obtain Nb2O5 micron flower supported Ru catalyst.
[0011] Preferably, in step (1), the ratio of niobium oxalate, ammonium carbonate and water is (1.5-1.7)g:(1.3-1.5)g:(40-50)ml.
[0012] Preferably, in step (1), the hydrothermal reaction temperature is 180-220°C and the hydrothermal reaction time is 12-14h.
[0013] Preferably, in step (1), the calcination temperature is 400-600℃, the holding time is 4-6h, and the heating rate is 2-5℃ / min.
[0014] Preferably, in step (2), the ratio of niobium pentoxide, ruthenium trichloride and water is (40-50) mg: (9-10) mg: 50 ml.
[0015] Preferably, in step (2), the hydrothermal reaction temperature is 100-120°C and the hydrothermal reaction time is 10-24h.
[0016] Preferably, in step (2), the annealing temperature is 300-500℃, the holding time is 2-5h, and the heating rate is 1-10℃ / min.
[0017] Preferably, in step (2), the vigorous stirring time is 12 to 14 hours.
[0018] The second aspect of this application also provides a Ru catalyst supported on Nb2O5 micron-shaped flowers based on a Lewis acid activation mechanism, which is prepared by the above method.
[0019] The third aspect of this application also provides the application of the aforementioned Nb2O5 micron-flower-supported Ru catalyst based on Lewis acid activation mechanism in the HER reaction of seawater electrolysis.
[0020] Compared with the prior art, this application has the following advantages:
[0021] 1. This application provides a method for preparing a ruthenium pentoxide micro-flower supported catalyst based on a Lewis acid catalytic mechanism. The catalyst is based on niobium pentoxide, which is resistant to chlorine corrosion, has a large specific surface area, is porous, and possesses ultra-long durability. Ruthenium, which exhibits high HER activity, is then supported on the niobium pentoxide. Nb₂O₅ is a typical strongly acidic Lewis acid, and the Nb₂O₅ surface contains Nb₂O₅ micro-flowers. 5+ The ion has empty orbitals, Nb 5+ By polarizing and adsorbing H₂O molecules, the OH bond is weakened, promoting water dissociation and generating hydrogen ions and hydroxide ions. The ruthenium loaded on the surface adsorbs hydrogen ions generated by water electrolysis, further promoting the HER step. Simultaneously, water electrolysis produces a large number of hydroxide ions. According to the hard-soft acid-base theory (HSAB), hydroxide ions are a harder acid than chloride ions and are more easily adsorbed onto the catalyst surface, hindering the Cl- adsorption process. - Approaching. Furthermore, the micron-sized flower-shaped pore structure achieves "reduced load and improved efficiency": the pores in Nb2O5 can ensure rapid electrolyte penetration, effectively alleviating the problem of bubble blockage. The mesoporous network formed by the self-assembly of nanosheets and the abundant micropore edge sites achieve ultra-high dispersion of ruthenium nanoparticles.
[0022] 2. This application utilizes the synergistic effect between niobium pentoxide support and metallic ruthenium to achieve high catalytic activity, excellent selectivity, and long-term stability of the Ru / Nb₂O₅ catalyst in seawater electrolysis systems. The preparation method is simple, convenient, and low-cost. The prepared Ru / Nb₂O₅ catalyst exhibits superior electrochemical activity and ultra-long-term stability compared to other seawater electrolysis HER catalysts: at -10 mA cm⁻¹... -2 At current density, the overpotential is only 37 mV, which is superior to the overpotential of commercial platinum-carbon (66 mV), and at -100 mAcm -2 It can stably electrolyze for over 150 hours at the specified current density, exhibiting superior electrocatalytic activity and stability compared to commercially available catalysts. Furthermore, the porous structure of Nb₂O₅ significantly increases the electrochemically active surface area (ECSA), and the double-layer capacitance (CDL) of Ru / Nb₂O₅ is 5.83 mF cm⁻¹. -2 Compared to Pt / C (3.32mF cm⁻¹), -2 The 75% increase indicates a significant increase in the number of active sites actually participating in the electrochemical reaction. More importantly, the large specific surface area of Nb₂O₅ reduces the Ru loading; inductively coupled plasma (ICP) analysis shows that the Ru mass fraction is only 2.3%, far lower than the Ru loading in other commercially available catalysts. This advantage stems from the high dispersion loading of Ru nanoparticles by the porous structure of Nb₂O₅, and the Lewis acid sites (Nb₂O₅, Nb₂O₅, and Nb₂O₅) on the support. 5+ The synergistic enhancement effect on interfacial proton transport provides a new research scheme for the industrial application of water electrolysis. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0024] Figure 1 The image shows the XRD pattern of the niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) prepared in Example 1.
[0025] Figure 2 The HER polarization curve of the niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) prepared in Example 1 in 1M KOH + seawater;
[0026] Figure 3 SEM image of niobium pentoxide (Nb2O5) prepared in Comparative Example 1;
[0027] Figure 4 SEM image of the niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) prepared in Example 1;
[0028] Figure 5 TEM image of the niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) prepared in Example 1;
[0029] Figure 6 The niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) prepared in Example 1 was tested at -100 mA cm⁻¹. -2 Stability image at current density;
[0030] Figure 7 The Cdl curves are for the niobium pentoxide-supported ruthenium catalyst (Ru / Nb2O5) and Pt / C prepared in Example 1. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0032] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.
[0033] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods.
[0034] Example 1
[0035] This embodiment provides a method for preparing a ruthenium pentoxide micro-flower supported catalyst, comprising the following steps:
[0036] (1) Preparation of niobium pentoxide micro-flowers: 1.6 g of niobium oxalate and 1.4 g of ammonium carbonate were dissolved in 50 ml of water and stirred vigorously for 20 min. The solution was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 220 °C for 12 h. The sample was washed repeatedly with water and ethanol alternately and then dried overnight in a 60 °C forced-air drying oven. The resulting white powder was calcined in a muffle furnace at a heating rate of 5 °C / min to 500 °C and held at that temperature for 6 h.
[0037] (2) Ruthenium loading: 40 mg of niobium pentoxide and 10 mg of ruthenium chloride trihydrate were dissolved in 50 ml of water and stirred vigorously for 12 h. The mixture was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 100 °C for 12 h. The sample was washed alternately with water and ethanol and then dried overnight in a 60 °C forced-air drying oven.
[0038] (3) Preparation of niobium pentoxide supported ruthenium catalyst: The above product was placed in a tube furnace and heated to 350°C at a heating rate of 5°C / min, and kept at that temperature for 2 hours.
[0039] Example 2
[0040] The niobium pentoxide micron-flowered supported ruthenium catalyst and its preparation method provided in this embodiment can be referred to in Example 1. The difference is that the amount of ruthenium used is the main invention point.
[0041] (1) Preparation of niobium pentoxide micro-flowers: 1.6 g of niobium oxalate and 1.4 g of ammonium carbonate were dissolved in 50 ml of water and stirred vigorously for 20 min. The solution was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 220 °C for 12 h. The sample was washed repeatedly with water and ethanol alternately and then dried overnight in a 60 °C forced-air drying oven. The resulting white powder was calcined in a muffle furnace at a heating rate of 5 °C / min to 500 °C and held at that temperature for 6 h.
[0042] (2) Ruthenium loading: 40 mg of niobium pentoxide and 9 mg of ruthenium chloride trihydrate were dissolved in 50 ml of water and stirred vigorously for 12 h. The mixture was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 100 °C for 12 h. The sample was washed alternately with water and ethanol and then dried overnight in a 60 °C forced-air drying oven.
[0043] (3) Preparation of niobium pentoxide supported ruthenium catalyst: The above product was placed in a tube furnace and heated to 350°C at a heating rate of 5°C / min, and kept at that temperature for 2 hours.
[0044] Example 3
[0045] The niobium pentoxide micron-flowered supported ruthenium catalyst and its preparation method provided in this embodiment can be referred to in Example 1, except that the reaction time is used as a variable.
[0046] (1) Preparation of niobium pentoxide micro-flowers: 1.6 g of niobium oxalate and 1.4 g of ammonium carbonate were dissolved in 50 ml of water and stirred vigorously for 20 min. The solution was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 220 °C for 12 h. The sample was washed repeatedly with water and ethanol alternately and then dried overnight in a 60 °C forced-air drying oven. The resulting white powder was calcined in a muffle furnace at a heating rate of 5 °C / min to 500 °C and held at that temperature for 6 h.
[0047] (2) Ruthenium loading: 40 mg of niobium pentoxide and 10 mg of ruthenium chloride trihydrate were dissolved in 50 ml of water and stirred vigorously for 14 h. The mixture was then transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 100 °C for 14 h. The sample was washed alternately with water and ethanol and then dried overnight in a 60 °C forced-air drying oven.
[0048] (3) Preparation of niobium pentoxide supported ruthenium catalyst: The above product was placed in a tube furnace and heated to 350°C at a heating rate of 5°C / min, and kept at that temperature for 2 hours.
[0049] Comparative Example 1
[0050] The preparation method of the niobium pentoxide micron flower catalyst in this comparative example includes the following steps:
[0051] (1) Preparation of niobium pentoxide micron flowers: 1.6 g of niobium oxalate and 1.4 g of ammonium carbonate were dissolved in 50 ml of water and stirred vigorously for 20 min. Then, the solution was transferred into a 100 ml polytetrafluoroethylene liner and sealed in an oven for solvothermal reaction at 220 °C for 12 h. The sample was washed repeatedly with water and ethanol alternately and then dried overnight in a 60 °C forced-air drying oven. The resulting white powder was calcined in a muffle furnace and heated to 500 °C at a heating rate of 5 °C / min, and held at that temperature for 6 h to obtain niobium pentoxide (Nb2O5).
[0052] Test case
[0053] (A) Elemental characterization of catalysts
[0054] The elemental composition of the niobium pentoxide-supported ruthenium catalyst was characterized by X-ray diffraction. Figure 1 ).from Figure 1 It can be seen that the prepared material corresponds to the standard card, further confirming that the catalyst is Ru / / Nb2O5.
[0055] (B) Cathode hydrogen evolution performance test
[0056] A three-electrode system was used to perform linear scan tests in saturated 1M KOH+ seawater at a scan rate of 5 mV / s. The prepared catalyst exhibited significantly superior hydrogen evolution performance compared to commercial platinum-carbon catalysts under alkaline seawater conditions. Figure 2 ), at -10mA cm -2 At current density, the overpotential is only 37mV, which is better than the overpotential of commercial platinum-carbon (66mV).
[0057] (C) Catalyst morphology characterization
[0058] SEM images were used to further reveal the structural morphology and characteristics of the prepared material, such as Figure 3 , Figure 4 As shown, the prepared Nb₂O₅ exhibits a micron-flower structure with a size of approximately 2–3 micrometers. The Ru / Nb₂O₅ catalyst formed after Ru loading still maintains the micron-flower structure, with Ru loaded in particle form on the Nb₂O₅ surface, and the Ru loading is uniform. Figure 5 As shown in the TEM image, Ru particles are loaded onto Nb2O5 nanosheets.
[0059] (D) Stability Test
[0060] The catalyst was tested using a chronopotentiometric method at -100 mA cm⁻¹. -2 Stability at current density. The prepared catalyst exhibits excellent stability. Figure 6 It has been running stably for over 150 hours without significant degradation.
[0061] (E) Double-layer capacitance (Cdl) test
[0062] A three-electrode system was used to perform cyclic voltammetry tests in saturated 1M KOH+ seawater at different scan rates within the non-Radida potential range (0.9–1V vs. RHE). Figure 7 The double-layer capacitance was calculated by fitting the linear slope of the charging current versus the scan rate at different scan rates (20–100 mV / s). The prepared Ru / Nb₂O₅ catalyst exhibited a significant electrochemical active surface area advantage under alkaline seawater conditions, with a Cdl value of 5.83 mF cm⁻¹. -2 It far exceeds that of commercial platinum-carbon catalysts (3.32 mF cm⁻¹). -2 The result indicates that the number of exposed active sites increased by approximately 75%. This result is consistent with the porous structure and highly dispersed Ru nanoparticles of the catalyst, further supporting its excellent hydrogen evolution performance.
[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A method for preparing a Ru catalyst supported on Nb₂O₅ micro-flowers based on a Lewis acid activation mechanism, characterized in that, Includes the following steps: (1) Niobium oxalate and ammonium carbonate are dissolved in water and stirred vigorously to obtain a mixture A. The mixture A is subjected to a hydrothermal reaction. After the reaction is completed, it is washed, dried and then calcined to obtain niobium pentoxide. (2) Niobium pentoxide, ruthenium trichloride and water are mixed and stirred vigorously to obtain mixture B. Mixture B is subjected to hydrothermal reaction. After the reaction is completed, it is washed, dried and then annealed to obtain Nb2O5 micron flower supported Ru catalyst.
2. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (1), the ratio of niobium oxalate, ammonium carbonate and water is (1.5-1.7)g:(1.3-1.5)g:(40-50)ml.
3. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (1), the hydrothermal reaction temperature is 180-220℃ and the hydrothermal reaction time is 12-14h.
4. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (1), the calcination temperature is 400-600℃, the holding time is 4-6h, and the heating rate is 2-5℃ / min.
5. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (2), the ratio of niobium pentoxide, ruthenium trichloride and water is (40-50) mg: (9-10) mg: 50 ml.
6. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (2), the hydrothermal reaction temperature is 100-120℃ and the hydrothermal reaction time is 10-24h.
7. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (2), the annealing temperature is 300-500℃, the holding time is 2-5h, and the heating rate is 1-10℃ / min.
8. The method for preparing the Nb₂O₅ micro-flower-supported Ru catalyst based on the Lewis acid activation mechanism according to claim 1, characterized in that, In step (2), the vigorous stirring time is 12 to 14 hours.
9. A Ru catalyst supported on Nb₂O₅ micro-flowers based on a Lewis acid activation mechanism, characterized in that, The Nb2O5 micro-flower-supported Ru catalyst based on Lewis acid activation mechanism prepared by the method described in any one of claims 1 to 8.
10. The application of the Nb2O5 micron-flower-supported Ru catalyst based on Lewis acid activation mechanism as described in claim 9 in the HER reaction of seawater electrolysis.