Preparation method and application of mesoporous ruthenium-titanium oxide solid solution catalyst

Abstract

This invention relates to a method for preparing and applying a mesoporous ruthenium titanium oxide solid solution catalyst. Addressing the problems of existing RuO₂ catalysts' easy dissolution and instability at acidic high potentials, the difficulty in achieving both structural controllability and large-scale production using traditional solid solution / mesoporous construction, and poor batch-to-batch consistency in conventional preparation routes, this invention proposes an integrated solution of "acidic complexation stabilization—controlled evaporation-induced micelle co-assembly—hydrothermal curing—inert / air heat treatment phase formation." This method has a wide process window, low equipment requirements, and is easily scaled up in trays / parallel configurations. It can achieve stable large-scale preparation while maintaining the homogeneity of the mesoporous structure and solid solution. The resulting catalyst can support high current density operation in PEMWE under low Ru loading and exhibits long-term durability, providing a replicable technical path for the engineering preparation and large-scale application of acidic oxygen evolution catalysts.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy and electrocatalytic materials technology, specifically relating to a method for preparing and applying a mesoporous ruthenium titanium oxide solid solution catalyst. Background Technology

[0002] Proton exchange membrane electrolysis (PEMWE) is one of the most ideal technologies for producing green hydrogen. However, its oxygen evolution reaction (OER) at the anolyte requires a strongly acidic, high-potential environment, which places extremely high demands on the activity and stability of the catalyst. Currently, commercially available catalysts mainly use iridium (Ir)-based catalysts, but the extreme scarcity and high cost of iridium limit the megawatt-scale deployment of PEMWE. Ruthenium dioxide (RuO2) has cost advantages and high activity, but it is extremely prone to peroxidation and dissolution (forming RuO4) under high current conditions, leading to rapid catalyst deactivation.

[0003] Constructing Ru-Ti solid solution oxides is an effective way to improve the stability of Ru-based catalysts. However, existing synthesis methods face a core technical bottleneck during scale-up production: a severe mismatch between the hydrolysis and polycondensation rates of Ru and Ti precursors. While this can be controlled in small-scale laboratory synthesis, in industrial-scale production (e.g., at the 100-gram level), this kinetic difference leads to severe phase separation, generating independent RuO2 and TiO2 phases, resulting in solid solution structure failure. Furthermore, traditional synthesis methods struggle to maintain uniform mesoporous structures and three-phase interface characteristics in large-scale preparations. Therefore, developing a Ru-Ti solid solution catalyst preparation process that overcomes kinetic obstacles, enables large-scale production, and delivers superior performance is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a mesoporous ruthenium titanium oxide solid solution catalyst, which is achieved through "acidic coordination stabilization—controlled evaporation gelation—hydrothermal curing—air calcination phase formation":

[0005] (1) Uniform solid solution of Ru in TiO2 lattice and suppression of excessive oxidation;

[0006] (2) The open mesopores and hierarchical structure are constructed in synergy, which is conducive to the establishment of three-phase interfaces and mass transfer and gas separation;

[0007] (3) Wide process parameter window, universal equipment, and easy to expand production from 10 grams to 100 grams or even larger batches.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The triblock copolymer was dissolved in an organic solvent, and a complexing agent and an acidic stabilizer were added to inhibit the rapid hydrolysis of the titanium source and regulate the synergistic condensation of ruthenium and titanium species. A uniform precursor solution was obtained by adding titanium and ruthenium sources. Under certain temperature and humidity conditions, a single micelle composite hydrogel was formed by preferential solvent evaporation. Subsequently, hydrothermal treatment was performed to solidify the radial mesoporous framework and induce crystallization initiation. Finally, the mixture was slowly heated and calcined in air to remove the template and promote lattice rearrangement and atomic diffusion, allowing Ru to enter the rutile TiO2 lattice to form a ruthenium titanium oxide solid solution, thereby obtaining a mesoporous ruthenium titanium oxide solid solution catalyst suitable for PEMWE anodes.

[0010] The preferred scalable preparation method specifically includes:

[0011] (1) At room temperature, the triblock copolymer is dissolved in an organic solvent, a complexing agent and an acidic stabilizer are added, and then a titanium source and a ruthenium source are added and stirred to obtain a uniform acidic precursor solution; (2) The precursor solution is placed at a certain temperature for controlled evaporation, and the relative humidity of the environment is controlled within the range of 20-60% to form a single micelle composite hydrogel; (3) The hydrogel is placed in a hydrothermal reactor for hydrothermal treatment; (4) The hydrothermal product is calcined in air to remove the template agent and obtain a mesoporous ruthenium titanium oxide solid solution catalyst.

[0012] The concentration of the triblock copolymer in the organic solvent is 0.045-0.055 g / mL; the concentrations of acetic acid and hydrochloric acid in the organic solvent are 0.065-0.085 g / mL and 0.10-0.12 g / mL, respectively; the concentration of tetrabutyl titanate in the organic solvent is 0.10-0.12 g / mL; and the concentration of ruthenium trichloride trihydrate in the organic solvent is 0.003-0.012 g / mL.

[0013] Preferably, in step (1), the organic solvent is tetrahydrofuran (THF), the titanium source is tetrabutyl titanate (TBOT), and the ruthenium source is ruthenium trichloride trihydrate (RuCl3·3H2O).

[0014] Preferably, the evaporation temperature in step (2) is 30-50 °C and the evaporation time is 12-24 h.

[0015] Preferably, the hydrothermal temperature in step (4) is 100-130 °C and the hydrothermal time is 24-48 h.

[0016] Preferably, the calcination temperature in step (5) is 350-450 °C, the heating rate is 1-2 °C / min, and the calcination time is 3-6 h.

[0017] Preferably, the triblock copolymer is polyethylene glycol-polypropylene glycol-polyethylene glycol, and the triblock copolymer mainly includes Pluronic F127 (EO) 106 PO 70 EO 106 ), Pluronic P123 (EO 20 PO 70 EO 20 ), the most preferred being Pluronic F127 (EO), etc. 106 PO 70 EO 106 ).

[0018] A mesoporous ruthenium titanium oxide solid solution synthesized using the above method has an emanating nanosphere morphology with a particle size of 500-700 nm.

[0019] A mesoporous ruthenium titanium oxide solid solution nanosphere was synthesized using the above method. The crystal phase is mainly composed of rutile TiO2 and forms a Ru-Ti oxide solid solution.

[0020] A mesoporous ruthenium titanium oxide solid solution nanosphere prepared by the above method has radially interconnected mesoporous channels and a specific surface area of ​​89 m². 2 / g, pore size of 9.0 nm, pore volume of 0.44 cm³ 3 / g.

[0021] A mesoporous ruthenium titanium oxide solid solution described above is used as an anode catalyst material for acidic PEMWE.

[0022] This invention employs an inorganic-organic co-assembly soft template self-assembly method. Through acidic complexation stabilization and controlled evaporation-induced micelle co-assembly strategies, a single-micelle composite gel precursor is formed during evaporation, followed by hydrothermal curing and heat treatment to achieve phase formation, thus realizing the controllable construction of mesoporous ruthenium titanium oxide solid solution (Ru-Ti-O) electrocatalytic materials. Characterization techniques such as SEM, TEM, XRD, N2 adsorption-desorption, and PEM electrolyzer evaluation were used to develop a novel, scalable synthesis method for mesoporous Ru-Ti oxide solid solution catalysts suitable for large-scale preparation. The effects of Ru solid solution regulation and open mesoporous hierarchical structure on acidic oxygen evolution kinetics, mass transfer and gas evolution behavior, and long-term stability were systematically investigated. A structure-property relationship of "solid solution electronic structure regulation—mesoporous three-phase interface construction—PEMWE anode performance enhancement" was established, providing a replicable material and process scheme for the engineering application of high current density and long-life PEM water electrolysis anode catalysts under low noble metal loading.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. Atomic-scale solid solution stabilization: Through acidic coordination and subsequent heat treatment, Ru is promoted to enter the TiO2 lattice to form a solid solution structure, which helps to suppress the excessive oxidation and structural disintegration of Ru under acidic high potential and improve long-term stability.

[0025] 2. Mesoscale three-phase interface optimization: The catalyst has open mesopores and hierarchical structure, which is conducive to reactant transport, ion / electron co-conduction and rapid bubble desorption, thereby improving the operating capability of PEMWE anode at high current density.

[0026] 3. The process is scalable and has strong batch-to-batch consistency: It adopts a general route of "controlled evaporation gelation + hydrothermal curing + air calcination", with low equipment requirements and a wide parameter window, which is suitable for palletized / parallel / continuous production expansion; by controlling the process of humidity and temperature, the formation of secondary phases is reduced, ensuring batch-to-batch structural consistency.

[0027] 4. Comprehensive advantages for PEMWE applications: It can achieve lower electrolyzer voltage, higher current density and long-term stable operation under lower Ru load, and has the application potential for large-scale green hydrogen production. Attached Figure Description

[0028] Figure 1 An optical image of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1 after calcination and weighing.

[0029] Figure 2 The image shows a scanning electron microscope (SEM) image of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1.

[0030] Figure 3 This is a transmission electron microscope (TEM) image of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1.

[0031] Figure 4 The images show aberration-corrected HAADF-STEM images of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1 after in-situ high-energy electron beam irradiation for different times. The white arrows indicate the gradual appearance of RuO2 nanoclusters on the pore walls over time, suggesting the separation of Ru element from the Ru-Ti oxide solid solution.

[0032] Figure 5 X-ray powder diffraction (XRD) pattern of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1;

[0033] Figure 6 The characteristic nitrogen adsorption-desorption isotherm of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1;

[0034] Figure 7Synchrotron radiation XANES and EXAFS images of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared in Example 1;

[0035] Figure 8 This is a comparison chart of the performance and stability of the mesoporous ruthenium titanium oxide solid solution nanospheres obtained in Example 2 as the PEMWE anode catalyst;

[0036] Figure 9 This is an optical image of the mesoporous ruthenium titanium oxide solid solution nanospheres prepared on a large scale in Example 3, after being calcined and weighed.

[0037] Figure 10 The image shows the X-ray powder diffraction (XRD) pattern of the large-scale prepared mesoporous ruthenium titanium oxide solid solution nanospheres obtained in Example 3. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0039] Example 1: Preparation of mesoporous ruthenium titanium oxide solid solution catalyst

[0040] A certain amount of triblock copolymer F127 (1.6 g) and ruthenium source RuCl3·3H2O (0.57 g) were added to tetrahydrofuran (30 ml), along with acetic acid (2.4 ml) as a complexing agent and concentrated hydrochloric acid (3.2 ml) as a stabilizer to inhibit rapid hydrolysis of the titanium source. After stirring evenly, tetrabutyl titanate (3.0 ml) was added, and stirring was continued to obtain a homogeneous acidic precursor solution. The solution was transferred to a container and evaporated under controlled conditions at approximately 45 °C for about 24 hours, while maintaining the relative humidity at approximately 40% to form a single micelle composite hydrogel. The hydrogel was then transferred to a polytetrafluoroethylene-lined sealed reaction vessel and hydrothermally treated at approximately 120 °C for about 24 hours. Finally, the hydrothermal product was heated in air at approximately 1 °C / min to approximately 400 °C and held for about 3 hours to obtain a mesoporous ruthenium titanium oxide solid solution catalyst. The yield after calcination was 0.77 g, as shown in the optical image. Figure 1 SEM images can be found Figure 2 See TEM image Figure 3 XRD images can be found Figure 5 SEM and TEM images confirm that the mesoporous ruthenium titanium oxide solid solution nanospheres have an radiating nanosphere morphology and good uniformity. Nitrogen adsorption-desorption curves are shown below. Figure 6 The obtained mesoporous ruthenium titanium oxide solid solution nanospheres have a specific surface area of ​​89 m². 2 / g, pore size of 9.0 nm, pore volume of 0.44 cm³3 / g. See images of XANES and EXAFS. Figure 7 The results show that the Ru valence state of the obtained material is approximately +3.90, indicating that the strong Ru–O–Ti interaction leads to lower valence and greater stability of the Ru sites, as well as the formation of Ru–Ti solid solutions and lattice distortion. Figure 4 This enhances the Ru–O bond strength, thereby improving the durability of acidic PEMWE.

[0041] Example 2: Application of PEMWE anodes and MEA preparation

[0042] The MEA was prepared using a catalyst-coated membrane (CCM) route: 40 mg of the mesoporous ruthenium titanium oxide solid solution catalyst of this invention was dispersed in a mixed solvent of isopropanol (600 μL) / water (600 μL), and 200 μL of Nafion solution was added as a binder and proton-conducting phase. The dispersion was ultrasonically performed to obtain the anode catalyst ink. The ink was then uniformly coated onto a proton exchange membrane Nafion 115 to form the anode catalyst layer, with a Ru loading of 0.4 mg / cm³. -2 The cathode uses commercial Pt / C (with a Pt loading of 0.3 mg / cm³). -2 The cathode layer was prepared in the same manner; after hot-pressing composite, it was assembled with the diffusion layer and bipolar plate to form a single cell. During testing, heated deionized water was supplied to the anode, and polarization curves and constant current stability tests were conducted at approximately 60°C. The results show that this type of solid solution mesoporous catalyst is suitable for high current density operation and possesses long-term stability advantages (1 A / cm²). -2 Stable operation for 400 hours); it can maintain a low electrolytic cell voltage even under low Ru load conditions (1 A / cm at 1.65 V). -2 (Current density) see Figure 8 .

[0043] Example 3: Industrial Scale-up and Production Recommendations (Applicable to 10-gram to 100-gram and above)

[0044] To achieve scalable preparation, the following scale-up strategies can be adopted: (1) Solution preparation scale-up: Use large-volume glass reaction vessels to ensure the ratio of complexing agent / acid stabilizer and stirring intensity, and maintain the uniformity of the precursor; (2) Evaporation gelation scale-up: Use evaporation methods such as multi-container or large-volume containers, maintain the temperature at 40-50℃ and stabilize the relative humidity at 20-60% (preferably 30-50%) to avoid excessive hydrolysis and secondary phase formation; (3) Hydrothermal curing scale-up: Use multiple reactors in parallel or larger-volume lined reactors, control the temperature at 100-150℃, and control the time at 12-36 hours to ensure that the mesoporous skeleton is fully cured; (4) Calcination scale-up: Slowly raise the temperature in air at 0.5-2℃ / min and keep it at that temperature to ensure that template removal and solid solution formation are completed simultaneously, thereby ensuring batch consistency and structural stability. The yield is shown in the figure. Figure 9 Approximately 15.8 g, with no change in crystal phase (see...) Figure 10 .

[0045] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. Those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a mesoporous ruthenium titanium oxide solid solution catalyst, characterized in that, Includes the following steps: S1: Dissolve at least one of the triblock copolymers Pluronic F127 and Pluronic P123 in tetrahydrofuran, then add acetic acid and concentrated hydrochloric acid to the tetrahydrofuran respectively, and finally add ruthenium and titanium metal precursors in portions to obtain mixed solution A. S2: Solution A is placed in an oven for treatment to allow it to evaporate and form a gel. The gel is then placed in a hydrothermal reactor for hydrothermal treatment. After hydrothermal treatment, the gel is centrifuged and calcined to obtain the sample.

2. The method for preparing a mesoporous ruthenium titanium oxide solid solution catalyst according to claim 1, characterized in that, The mass ratio of the triblock copolymer in S1: tetrahydrofuran: acetic acid: concentrated hydrochloric acid: ruthenium metal precursor: titanium metal precursor is 1: (15-20): (1.2-2.0): (2.0-3.0): (0.05-0.30): (1.5-2.2).

3. The method for preparing a mesoporous ruthenium titanium oxide solid solution catalyst according to claim 1, characterized in that, The solution in S2 is allowed to stand at a temperature of 30-50 °C for 12-24 h.

4. The method for preparing a mesoporous ruthenium titanium oxide solid solution catalyst according to claim 1, characterized in that, The hydrothermal temperature in S2 is 100-130 °C, and the hydrothermal time is 24-48 h.

5. The method for preparing a mesoporous ruthenium titanium oxide solid solution catalyst according to claim 1, characterized in that, The calcination temperature of S2 is 400-600 °C, and the calcination time is 3-6 h.

6. A mesoporous ruthenium titanium oxide solid solution catalyst, characterized in that, The catalyst is a Ru-Ti oxide solid solution with a uniform mesoporous structure. Ru and Ti are atomically dispersed and alternately intercalated in the oxide lattice, forming a solid solution framework bridged by Ru-O-Ti bonds. The pore size is 6-15 nm, and the specific surface area is 50-150 m². 2 / g, pore volume 0.3-0.44cm 3 / g, with an open pore structure.

7. An application of the mesoporous ruthenium titanium oxide solid solution catalyst as described in claim 6, used as an electrocatalyst for the oxygen evolution reaction at the anode in proton exchange membrane water electrolysis (PEMWE).

Images