A Ru / Co-Sm 2 O 3 Composite catalysts, their preparation methods and applications

Abstract

This invention relates to the field of hydrogen production catalyst technology, and in particular to a Ru / Co-Sm catalyst. 2 O 3 Composite catalysts, their preparation methods, and applications. This catalyst uses Co-Sm... 2 O 3 As a carrier, Ru is loaded on the carrier; the Ru / Co-Sm 2 O 3 The Ru loading in the composite catalyst ranged from 2.4 to 7.1 wt.%. This was achieved by loading Ru onto the heterostructure Co-Sm... 2 O 3 Obtained on a carrier. This Ru / Co-Sm 2 O 3 Composite catalysts possess mesoporous structures and abundant specific surface areas, resulting in numerous exposed active sites, making them highly catalytically active in hydrogen desorption from water. This invention employs a simple preparation method, utilizing a straightforward hydrothermal synthesis, a metal-organic framework pyrolysis strategy, and an in-situ reduction loading method to successfully prepare a novel Co and Sm... 2 O 3 Nonmetallic element co-doped heterostructure Ru / Co-Sm 2 O 3 Composite material catalysts.

Description

A Ru / Co-Sm2O3 composite catalyst, its preparation method and application Technical Field

[0001] This invention relates to the field of hydrogen production catalyst technology, and in particular to a Ru / Co-Sm2O3 composite catalyst, its preparation method, and its application. Background Technology

[0002] In recent years, there has been a strong push to develop and utilize clean and sustainable energy sources, such as solar, wind, and tidal energy. However, these renewable energy sources are often susceptible to external factors (such as sunshine and wind intensity), making it difficult to provide a stable and continuous energy supply, which seriously affects their storage, transportation, and use in production and daily life.

[0003] Hydrogen (H2) has a high energy density (142 MJ / kg). -1 Hydrogen hydride (H2) is considered a promising energy carrier due to its environmentally friendly combustion products and potential applications in energy conversion devices, making it one of the most suitable energy sources to replace fossil fuels. However, the storage and transportation of H2 typically involves complex conditions such as high pressure and specialized equipment, which severely restricts its widespread application. NaBH4 not only has a high hydrogen storage density (10.57 wt.%) but can also be stably stored in alkaline solutions, making it one of the ideal hydrogen sources (such as NaBH4, NH3BH3, and MgH2) for portable energy conversion devices. However, the self-hydrolysis of sodium borohydride to produce hydrogen is very slow, requiring highly efficient catalysts to increase the reaction rate to meet rapid energy demands. Currently, sodium borohydride hydrogen evolution catalysts are mainly noble metal-based catalysts, such as PdO-Co3O4, Ru@CoAl-LDH, and Pt-Ni. Due to the excessively high noble metal loading or poor activity of some catalysts, their cost and stability are less than ideal. Therefore, seeking efficient and economical hydrogen evolution catalysts is an effective way to develop a hydrogen economy. Summary of the Invention

[0004] Based on the above, this invention provides a Ru / Co-Sm2O3 composite catalyst, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] One of the technical solutions of the present invention is a Ru / Co-Sm2O3 composite catalyst, which uses Co-Sm2O3 as a support and loads Ru on the support; the loading amount of Ru in the Ru / Co-Sm2O3 composite catalyst is 2.4-7.1 wt.%.

[0007] The second technical solution of the present invention is a method for preparing the above-mentioned Ru / Co-Sm2O3 composite catalyst, comprising the following steps:

[0008] Sm salt and Co salt are dissolved in an organic solvent to obtain solution A;

[0009] Pyromellitic acid is dissolved in an organic solvent to obtain solution B;

[0010] Solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain CoSm-BTC; CoSm-BTC is then calcined to obtain Co-Sm2O3.

[0011] The Co-Sm2O3 and ruthenium salt were dissolved in a solvent to obtain a mixed solution; an ammonia borane solution was added to the mixed solution and stirred to perform in-situ reduction loading to obtain the Ru / Co-Sm2O3 composite catalyst.

[0012] The third technical solution of this invention is the application of the above-mentioned Ru / Co-Sm2O3 composite catalyst in hydrogen production by water electrolysis.

[0013] The fourth technical solution of the present invention is a method for improving the hydrogen production rate by hydrolysis of NaBH4, wherein the above-mentioned Ru / Co-Sm2O3 composite material catalyst is added to NaBH4, NH3BH3 or MgH2 solution.

[0014] The present invention discloses the following technical effects:

[0015] This invention provides a core-shell Ru / Co-Sm2O3 composite catalyst, obtained by supporting Ru on a heterostructured Co-Sm2O3 support. This core-shell Ru / Co-Sm2O3 composite catalyst possesses a mesoporous structure and abundant specific surface area, with numerous exposed active sites, exhibiting strong catalytic activity in the field of hydrogen desorption from water.

[0016] The present invention has a simple preparation method. By using a simple hydrothermal synthesis, metal-organic framework pyrolysis strategy and in-situ reduction loading method, a new heterostructure Ru / Co-Sm2O3 composite catalyst co-doped with non-metallic elements such as Co and Sm2O3 was successfully prepared.

[0017] The Ru / Co-Sm2O3 composite catalyst of this invention exhibits excellent hydrogen release performance from sodium borohydride water, and retains high catalytic activity even after five repeated stability tests, indicating its excellent reusability. This multi-component synergistic catalyst provides a novel method for preparing superior catalysts. Furthermore, this catalyst holds promise for development in other research areas. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 shows the scanning electron microscope (SEM) image, high-resolution transmission electron microscope (HRTEM) image, and elemental distribution map of the catalyst Ru / Co-Sm2O3 prepared in Example 6; where a is the SEM image, b is the HRTEM image, and c is the elemental distribution map.

[0020] Figure 2 shows the X-ray powder diffraction patterns of the catalysts prepared in Examples 1-7, and the nitrogen adsorption-desorption isotherm of the Ru / Co-Sm2O3 catalyst prepared in Example 6; wherein, a is the X-ray powder diffraction pattern of the catalysts prepared in Examples 1-7, and b is the nitrogen adsorption-desorption isotherm of the Ru / Co-Sm2O3 catalyst prepared in Example 6.

[0021] Figure 3 shows the hydrogen evolution performance diagram a and the hydrogen evolution rate summary diagram b for the catalysts prepared by Co, Sm2O3, Co-Sm2O3, and Examples 1, 2, and 6, and the hydrogen evolution performance diagram c and the hydrogen evolution rate summary diagram d for the catalysts prepared in Examples 3-7.

[0022] Figure 4 shows the logarithmic fitting curves of ln(rate) and ln(NaBH4) of the catalyst prepared in Example 6 (a), the performance graph of hydrogen evolution rate as a function of test temperature (b), the hydrogen evolution performance graph of five-cycle stable test (c), and the summary graph of hydrogen evolution rate of five-cycle stable test (d). Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] The first aspect of the present invention provides a Ru / Co-Sm2O3 composite catalyst, which uses a heterostructure Co-Sm2O3 as a support and loads Ru on the support; the loading amount of Ru in the Ru / Co-Sm2O3 composite catalyst is 2.4-7.1 wt%.

[0029] In a further preferred embodiment of the present invention, the Ru loading in the Ru / Co-Sm2O3 composite catalyst is 4.75 wt.%.

[0030] Both high and low Ru loading in the catalyst will affect the catalytic performance of the catalyst. Through repeated experiments, this invention found that the catalytic performance is best when the Ru loading in the Ru / Co-Sm2O3 composite catalyst is 4.75 wt.%.

[0031] In a preferred embodiment of the present invention, the microstructure consists of microspheres with an average particle size of 2.2 μm, an average pore size of 15.1 nm, and a specific surface area of ​​101.7 m². 2 g -1 .

[0032] A second aspect of the present invention provides a method for preparing the above-mentioned Ru / Co-Sm2O3 composite catalyst, comprising the following steps:

[0033] Sm salt and Co salt are dissolved in an organic solvent to obtain solution A;

[0034] Pyromellitic acid is dissolved in an organic solvent to obtain solution B;

[0035] Solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain CoSm-BTC; CoSm-BTC is then calcined to obtain Co-Sm2O3.

[0036] The Co-Sm2O3 and ruthenium salt were dissolved in a solvent to obtain a mixed solution; an ammonia borane solution was added to the mixed solution and stirred to perform in-situ reduction loading to obtain the Ru / Co-Sm2O3 composite catalyst.

[0037] In a preferred embodiment of the present invention, the sum of the concentrations of Sm salt and Co salt in solution A is 0.067-0.201 mol / L;

[0038] The molar ratio of the Sm salt to the Co salt is 1:(1-40);

[0039] The Sm salt is at least one selected from Sm(NO3)3·6H2O, SmCl3·6H2O, and Sm2(SO4)3·8H2O; the Co salt is at least one selected from Co(NO3)2·6H2O, CoCl2·6H2O, and CoSO4·7H2O.

[0040] The concentration of the ligand in solution B is 0.18-0.22 mol / L; the ligand is pyromellitic acid; solution B also contains 8 mg / mL of polyvinylpyrrolidone.

[0041] The organic solvent in both solution A and solution B is N,N-dimethylformamide.

[0042] The sum of the amounts of the Sm salt and Co salt is in a molar ratio of 1:1 to the ligand.

[0043] In a preferred embodiment of the present invention, the hydrothermal reaction is carried out at a temperature of 160°C for 24 hours.

[0044] The hydrothermal reaction also includes steps of centrifugation to collect the product, washing, and drying.

[0045] The calcination temperature is 700-900℃, and the time is 1-4 hours. If the calcination time is too short, the calcination will not be sufficient and may cause inconsistent composition. If the calcination time is too long, the energy consumption will be increased. Therefore, considering both the effect and energy consumption, the present invention limits the calcination time to 1-4 hours, and more preferably 1-3 hours.

[0046] In a preferred embodiment of the present invention, the mass ratio of Co-Sm2O3 to ruthenium salt is 50:9.

[0047] The solvent can be at least one of water, ethanol, and isopropanol; the solvent serves to disperse Co-Sm2O3 and to dissolve the ruthenium salt (ruthenium trichloride) solid.

[0048] The ratio of ammonia borane content to the amount of Co-Sm2O3 in the ammonia borane solution is 0.13 mol: 50 mg. Ammonia borane acts as a reducing agent for the metal in this invention. Insufficient ammonia borane will lead to incomplete ruthenium reaction, while excessive ammonia borane will result in a prolonged reaction time, decomposition during the reaction producing bubbles, and waste of reagents.

[0049] In a preferred embodiment of the present invention, the ruthenium salt is ruthenium trichloride and / or ruthenium acetylacetonate.

[0050] In a preferred embodiment of the present invention, Co-Sm2O3 is first dissolved in a mixed solvent and stirred, then ruthenium salt is added and sonicated to obtain a mixed solution; the mixed solution is stirred for 5-8 hours, and then ammonia borane solution is added to the mixed solution and stirred for 1-4 hours for in-situ reduction loading, the sample is collected by centrifugation, and the sample is washed to obtain the Ru / Co-Sm2O3 composite catalyst.

[0051] The third aspect of the present invention provides the application of the above-mentioned Ru / Co-Sm2O3 composite catalyst in hydrogen production by water electrolysis.

[0052] The fourth aspect of the present invention provides a method for improving the hydrogen production rate by hydrolysis of NaBH4, wherein the above-mentioned Ru / Co-Sm2O3 composite catalyst is added to a NaBH4, NH3BH3 or MgH2 solution.

[0053] In a preferred embodiment of the present invention, the mass ratio of NaBH4 to Ru / Co-Sm2O3 composite catalyst in the NaBH4 solution is 24:1.

[0054] Unless otherwise specified, all raw materials used in the embodiments of this invention can be obtained through commercial channels.

[0055] The solvent used in the ammonia borane solution in the embodiments of the present invention is water (ethanol and methanol are also applicable as solvents in the present invention).

[0056] The present invention will be further illustrated by the following examples.

[0057] Example 1: Preparation of Ru / Co

[0058] Preparation of solution A: Weigh 3 mmol of Co(NO3)2·6H2O and dissolve it in 30 mL of N,N-dimethylformamide (DMF). Sonicate for 30 minutes to obtain solution A.

[0059] Preparation of solution B: Weigh 120 mg of polyvinylpyrrolidone (PVP) and 3 mmol of pyromellitic acid, dissolve them in 15 mL of LDM, and sonicate for 30 min to obtain solution B;

[0060] Solution A and solution B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried in a blower at 60℃ (50-70℃ is also acceptable) for 6 hours to obtain Co-BTC. 100 mg of Co-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co powder was obtained.

[0061] 50 mg of black Co powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously, and the mixture was stirred for 30 min. Then, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Next, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black Ru / Co powder (catalyst).

[0062] Example 2: Preparation of Ru / Sm2O3

[0063] Preparation of solution A: Weigh 3 mmol of Sm(NO3)3·6H2O, dissolve it in 30 mL of LDMF, and sonicate for 30 min to obtain solution A;

[0064] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0065] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain Sm-BTC. 100 mg of Sm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Sm2O3 powder was obtained.

[0066] 50 mg of black Sm₂O₃ powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black Ru / Sm₂O₃ powder (catalyst).

[0067] Example 3: Preparation of Ru / Co-Sm2O3-1 (Co:Sm = 1:1)

[0068] Preparation of solution A: Weigh 1.5 mmol Sm(NO3)3·6H2O and 1.5 mmol Co(NO3)2·6H2O and dissolve them in 30 mL LMF. Sonicate for 30 minutes to obtain solution A.

[0069] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0070] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain CoSm-BTC. 100 mg of CoSm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co-Sm2O3 powder was obtained.

[0071] 50 mg of black Co-Sm2O3 powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black powder Ru / Co-Sm2O3-1 (catalyst).

[0072] Example 4: Preparation of Ru / Co-Sm2O3-2 (Co:Sm = 10:1)

[0073] Preparation of solution A: Weigh 0.273 mmol Sm(NO3)3·6H2O and 2.727 mmol Co(NO3)2·6H2O and dissolve them in 30 mL LDM. Sonicate for 30 min to obtain solution A.

[0074] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0075] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain CoSm-BTC. 100 mg of CoSm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co-Sm2O3 powder was obtained.

[0076] 50 mg of black Co-Sm₂O₃ powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black powder Ru / Co-Sm₂O₃⁻₂ (catalyst).

[0077] Example 5: Preparation of Ru / Co-Sm2O3-3 (Co:Sm = 20:1)

[0078] Preparation of solution A: Weigh 0.143 mmol Sm(NO3)3·6H2O and 2.857 mmol Co(NO3)2·6H2O and dissolve them in 30 mL LMF. Sonicate for 30 min to obtain solution A.

[0079] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0080] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain CoSm-BTC. 100 mg of CoSm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co-Sm2O3 powder was obtained.

[0081] 50 mg of black Co-Sm₂O₃ powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black powder Ru / Co-Sm₂O₃⁻ (catalyst).

[0082] Example 6: Preparation of Ru / Co-Sm2O3 (Co:Sm = 30:1)

[0083] Preparation of solution A: Weigh 0.097 mmol Sm(NO3)3·6H2O and 2.903 mmol Co(NO3)2·6H2O and dissolve them in 30 mL LMF. Sonicate for 30 min to obtain solution A.

[0084] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0085] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain CoSm-BTC. 100 mg of CoSm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co-Sm2O3 powder was obtained.

[0086] 50 mg of black Co-Sm₂O₃ powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black Ru / Co-Sm₂O₃ powder (catalyst).

[0087] Example 7: Preparation of Ru / Co-Sm2O3-4 (Co:Sm = 40:1)

[0088] Preparation of solution A: Weigh 0.073 mmol Sm(NO3)3·6H2O and 2.927 mmol Co(NO3)2·6H2O and dissolve them in 30 mL LMF. Sonicate for 30 min to obtain solution A.

[0089] Preparation of solution B: Weigh 120 mg PVP and 3 mmol pyromellitic acid, dissolve them in 15 mL LMF and sonicate for 30 min to obtain solution B;

[0090] Solutions A and B were mixed thoroughly and then hydrothermally reacted in a reactor at 160℃ for 24 hours. The product was collected by centrifugation, washed three times with DMF, and finally dried at 60℃ for 6 hours in a blower dryer to obtain CoSm-BTC. 100 mg of CoSm-BTC was weighed and placed in a quartz boat. In a tube furnace, using argon as a protective gas, the temperature was increased to 800℃ at 5℃ / min and held for 3 hours. After natural cooling, black Co-Sm2O3 powder was obtained.

[0091] 50 mg of black Co-Sm₂O₃ powder was weighed and placed in a 100 mL beaker. 30 mL of water and 10 mL of ethanol were added simultaneously. After stirring for 30 min, 9 mg of ruthenium trichloride was added, and the mixture was sonicated for 30 min. The resulting solution was stirred at room temperature for 6 h. Then, 5 mL of 0.13 M ammonia borane aqueous solution was added dropwise to the solution, and stirring was continued for 2 h. The sample was collected by centrifugation, washed three times with water and ethanol, and then dried in a vacuum drying oven at 40 °C for 12 h to obtain black powder Ru / Co-Sm₂O₃⁻⁴ (catalyst).

[0092] Effect verification example

[0093] The catalysts prepared in Examples 1-7 were tested using the following methods:

[0094] 20 mL of a 0.6 wt.% NaBH4 aqueous solution (containing 0.4 wt.% NaOH) was added to a 50 mL double-necked round-bottom flask, and the mixture was continuously stirred in a 25°C water bath until the reading of the connected electronic balance remained constant. Then, 5 mg of catalyst was added, and the evolved hydrogen gas was collected by water displacement. The water displaced by the balance was weighed, and the mass of the displaced water was recorded instantaneously using a computer connected to the balance. Simultaneously, the computer program calculated the volume of hydrogen gas produced per unit time, thereby calculating the hydrogen evolution rate.

[0095] The hydrogen evolution rate (HGR) is calculated using the following formula:

[0096]

[0097] in, t is the displacement, m is the mass of the catalyst, and t is the total reaction time.

[0098] Other microstructure, X-ray powder diffraction, nitrogen adsorption-desorption and other testing methods are conventional techniques in this field and are not the focus of this invention's patent protection, so they will not be described in detail here.

[0099] The results are as follows:

[0100] Figure 1 shows the scanning electron microscope (SEM) image, high-resolution transmission electron microscope (HRTEM) image, and elemental distribution map of the catalyst Ru / Co-Sm2O3 prepared in Example 6; where a is the SEM image, b is the HRTEM image, and c is the elemental distribution map.

[0101] Figure 1a shows that Ru / Co-Sm2O3, after hydrothermal synthesis, calcination at 800℃, and Ru reduction loading, exhibits rough-surfaced microspheres. The rough surface provides a larger specific surface area, thereby generating more active sites and enhancing catalyst activity. Figure 1b shows the lattice spacing as follows: and The figures correspond to the Co (111), Ru (100), and Sm₂O₃ (222) crystal planes, respectively, demonstrating the successful preparation of the Ru / Co-Sm₂O₃ composite material. Figure 1c shows that Ru, Co, Sm, and O elements are uniformly distributed within the microspheres. Co forms the core of the microspheres, while Ru and Sm₂O₃ species are uniformly distributed on the surface. This core-shell structure between species provides more active sites for the catalyst, enhancing its intrinsic activity.

[0102] Figure 2 shows the X-ray powder diffraction patterns of the catalysts prepared in Examples 1-7 (same as Examples 1-7), and the nitrogen adsorption-desorption isotherm of the Ru / Co-Sm2O3 catalyst prepared in Example 6; wherein, a is the X-ray powder diffraction pattern of the catalysts prepared in Examples 1-7, and b is the nitrogen adsorption-desorption isotherm of the Ru / Co-Sm2O3 catalyst prepared in Example 6.

[0103] As shown in Figure 2a, the Ru / Co ratio of Example 1 matches the standard Co card (JCPDS: 89-4307), and the Ru / Sm2O3 ratio of Example 2 matches the standard Sm2O3 card (JCPDS: 42-1464), further confirming the crystal structure of the composite material prepared in this invention. No Ru diffraction peaks were found, possibly due to the small size or low content of Ru particles. Inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed that the Ru content in the catalysts prepared in Examples 1-7 was 4.75 wt.%. The lower noble metal content reduces costs while effectively improving the intrinsic activity of the catalyst and increasing the utilization rate of the noble metal. The peak intensity of the X-ray powder diffraction patterns in Examples 3, 4, 5, 6, and 7 decreases with decreasing Sm2O3 content, indicating that Sm2O3 mainly plays a role in regulating the electronic interactions between catalyst components. The optimally regulated Sm₂O₃ catalyst (Ru / Co-Sm₂O₃ prepared in Example 6) was further subjected to nitrogen adsorption-desorption tests to characterize its specific surface area. A distinct hysteresis loop was observed within the relative pressure range (p / p₀ = 0.4–0.9), indicating the presence of mesoporous structures in the catalyst, with an average pore size of approximately 15.1 nm. This unique mesoporous structure facilitates mass transport and adsorption. The results show that the catalyst prepared in Example 6 has a specific surface area of ​​101.7 m². 2 g -1 A large specific surface area is beneficial for exposing more active sites, thereby enhancing catalytic activity.

[0104] Figure 3 shows the hydrogen evolution performance diagram a and the hydrogen evolution rate summary diagram b for the catalysts prepared by Co, Sm2O3, Co-Sm2O3, and Examples 1, 2, and 6, and the hydrogen evolution performance diagram c and the hydrogen evolution rate summary diagram d for the catalysts prepared in Examples 3-7.

[0105] Figures 3a and 3b show that the catalyst prepared in Example 6 exhibits the optimal hydrogen evolution rate per unit time, reaching as high as 9636 mL / min. -1 g -1 In Example 6, the catalytic performance of Ru / Co-Sm2O3 was superior to that of a single precursor (Co, Sm2O3, Co-Sm2O3, Ru / Co, and Ru / Sm2O3), demonstrating a strong synergistic effect among the composite material components. Figures 3c and 3d show that as the Sm2O3 content decreases, the hydrogen evolution rate exhibits a volcano-shaped trend, ultimately revealing that the optimal hydrogen evolution rate is achieved when the Co:Sm molar ratio is 30:1. This superior catalytic performance stems from Sm2O3 modulating the electronic structure between Ru and the Co-Sm2O3 support in the catalyst, resulting in optimal electronic interactions in the catalyst (Example 6).

[0106] Figure 4 shows the logarithmic fitting curves of ln(rate) and ln(NaBH4) of the catalyst prepared in Example 6 (a), the performance graph of hydrogen evolution rate as a function of test temperature (b), the hydrogen evolution performance graph of five-cycle stable test (c), and the summary graph of hydrogen evolution rate of five-cycle stable test (d).

[0107] The optimal support metal ratio was obtained through the Sm2O3-controlled catalyst described above. Further characterization tests were conducted on the optimal catalyst (Example 6) with different concentrations of test solutions and its catalytic stability to explore the reasons for its excellent catalytic performance. Figure 4a shows the logarithmic fitting curves of ln(rate) and ln(NaBH4) for the catalyst of Example 6. It can be seen that the k-value of ln(rate) as a linear function of ln(NaBH4) is 0.069, close to zero, indicating that the hydrogen evolution rate of the catalyst in Example 6 is unaffected by the NaBH4 concentration within a certain range. The hydrogen evolution rate of Example 6 is a zero-order reaction with respect to NaBH4 concentration. Figure 4b shows the performance graph of the hydrogen evolution rate of the catalyst in Example 6 as a function of test temperature. With increasing temperature, the hydrogen evolution rate continuously increases, indicating that the catalyst performance is directly proportional to its thermodynamic energy. The reusability rate of the catalyst is one of the important indicators for evaluating excellent catalysts. Figures 3c and 3d summarize the hydrogen evolution performance and hydrogen evolution rate of the catalyst in Example 6 after five cycles of stability testing. It can be seen that the hydrogen evolution rate decreases slowly with increasing stability testing. After five cycles of testing, the catalyst activity remained above 74.1%, demonstrating that the Ru / Co-Sm2O3 catalyst prepared in Example 6 has excellent stability.

[0108] In summary, this invention synthesized a series of CoSm-BTC metal-organic frameworks using different proportions of Co and Sm metals via a hydrothermal method. The optimal catalyst was then obtained through high-temperature calcination at 800℃ under an inert gas atmosphere (argon or nitrogen) and in-situ Ru loading. Various physical characterization techniques were employed to investigate the catalyst's structure and morphology, including scanning electron microscopy and transmission electron microscopy to examine its morphology and structure, and X-ray powder diffraction to investigate its crystal structure, further confirming its crystal structure. Simultaneously, nitrogen adsorption-desorption was used to investigate the catalyst's pore size and specific surface area. These characterization and performance tests demonstrate the synthesis of an excellent Ru / Co-Sm₂O₃ hydrogen evolution catalyst. The catalyst synthesis process involves the pyrolysis of the metal-organic framework and in-situ reduction of noble metals. This method is simple, the catalyst is easy to mold, and it exhibits strong reproducibility, potentially providing an effective and novel pathway for the development of superior catalysts.

[0109] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A Ru / Co-Sm2O3 composite catalyst for improving the hydrogen production rate by hydrolysis of NaBH4, characterized in that, Using Co-Sm₂O₃ as a support, Ru is loaded onto the support; the Ru / Co-Sm₂O₃ composite catalyst has a Ru loading of 4.75 wt%; its microstructure consists of micron-sized spheres; the average pore size is 15.1 nm; and the specific surface area is 101.7 m². 2 g -1 The preparation method of the Ru / Co-Sm2O3 composite catalyst includes the following steps: dissolving Sm salt and Co salt in an organic solvent to obtain solution A; dissolving the ligand in an organic solvent to obtain solution B; mixing solution A and solution B and performing a hydrothermal reaction to obtain CoSm-BTC; calcining the CoSm-BTC to obtain Co-Sm2O3; dissolving the Co-Sm2O3 and ruthenium salt in a solvent to obtain a mixed solution; adding ammonia borane solution to the mixed solution and stirring to perform in-situ reduction loading to obtain the Ru / Co-Sm2O3 composite catalyst; the molar ratio of Sm salt to Co salt is 1:30; the temperature of the hydrothermal reaction is 160℃ and the time is 24h; the temperature of the calcination is 700-900℃ and the time is 1-4h; the ligand in solution B is trimesic acid.

2. A method for preparing the Ru / Co-Sm2O3 composite catalyst according to claim 1, characterized in that, Includes the following steps: Sm salt and Co salt are dissolved in an organic solvent to obtain solution A; The ligand is dissolved in an organic solvent to obtain solution B; solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain CoSm-BTC; CoSm-BTC is calcined to obtain Co-Sm2O3; Co-Sm2O3 and ruthenium salt are dissolved in a solvent to obtain a mixed solution; ammonia borane solution is added to the mixed solution and stirred for in-situ reduction loading to obtain the Ru / Co-Sm2O3 composite catalyst; the molar ratio of Sm salt to Co salt is 1:30; the hydrothermal reaction temperature is 160℃ and the time is 24h; the calcination temperature is 700-900℃ and the time is 1-4h; the ligand in solution B is pyromellitic acid.

3. The method for preparing the Ru / Co-Sm2O3 composite catalyst according to claim 2, characterized in that, The sum of the concentrations of Sm salt and Co salt in solution A is 0.067-0.201 mol / L; the Sm salt is at least one selected from Sm(NO3)3·6H2O, SmCl3·6H2O, and Sm2(SO4)3·8H2O; the Co salt is at least one selected from Co(NO3)2·6H2O, CoCl2·6H2O, and CoSO4·7H2O; the concentration of the ligand in solution B is 0.18-0.22 mol / L; solution B also includes 8 mg / mL of polyvinylpyrrolidone; the organic solvent in both solution A and solution B is N,N-dimethylformamide; the molar ratio of the sum of the amounts of Sm salt and Co salt to the ligand is 1:

1.

4. The method for preparing the Ru / Co-Sm2O3 composite catalyst according to claim 2, characterized in that, The mass ratio of Co-Sm2O3 to ruthenium salt is 50:9; the solvent is at least one of water, ethanol, and isopropanol; the ratio of the content of ammonia borane in the ammonia borane solution to the amount of Co-Sm2O3 is 0.13 mol: 50 mg; the ruthenium salt is ruthenium trichloride and / or ruthenium acetylacetonate.

5. The application of the Ru / Co-Sm2O3 composite catalyst as described in claim 1 in hydrogen production by water electrolysis.

6. A method for increasing the rate of hydrogen production by hydrolysis of NaBH4, characterized in that, Add the Ru / Co-Sm2O3 composite catalyst of claim 1 to a NaBH4 solution.

7. The method for increasing the hydrogen production rate by hydrolysis of NaBH4 according to claim 6, characterized in that, The mass ratio of NaBH4 to Ru / Co-Sm2O3 composite catalyst in the NaBH4 solution is 24:1.

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