Carrier-stabilized ruthenium-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a carrier-stabilized ruthenium-based catalyst and a preparation method and application thereof.The catalyst comprises a non-noble metal oxide carrier and ruthenium-based oxygen evolution active ingredients loaded on the non-noble metal oxide carrier, and the catalytic activity is improved by means of structural defects and oxygen vacancies of the non-noble metal oxide carrier; meanwhile, the combination of the non-noble metal oxide carrier and the ruthenium precursor salt is enhanced by treating the ruthenium precursor salt and the non-noble metal oxide carrier through low-boiling-point alcohol and sintering at two sections of continuous temperatures, and a heterojunction and a microcrystalline structure are constructed between the non-noble metal oxide carrier and the mixed crystal phase ruthenium-based oxide, so that the stabilization of the catalyst is realized; benefited from this unique morphology, the catalyst of the present invention exhibits very excellent OER performance and long-term stability.

Description

Technical field:

[0001] The invention relates to the technical field of catalysts for producing hydrogen by electrolysis of water, and in particular to a carrier-stabilized ruthenium-based catalyst and a preparation method and application thereof. Background technology:

[0002] Hydrogen production by water electrolysis is a very promising green hydrogen production technology. Among various water electrolysis technologies, proton exchange membrane (PEM) water electrolysis has attracted widespread attention due to its advantages such as high current density and high efficiency. However, the high overpotential of acidic media and oxygen evolution reaction greatly limits the choice of catalytic materials. Expensive iridium-based catalysts are required in current commercial products. The scarcity of iridium makes it impossible to meet the large-scale application requirements of PEM electrolyzers. In contrast, ruthenium-based materials have better oxygen evolution reaction activity and are cheap and abundant, making them the best potential substitutes for iridium-based catalysts. However, ruthenium-based catalysts will be oxidized to unstable RuO at the high oxidation potential of the oxygen evolution reaction. 4 2- However, the currently developed ruthenium-based catalysts are difficult to meet the life requirements of water electrolysis applications due to dissolution. Therefore, the development of ruthenium-based catalysts with both high activity and high stability is an important development direction for the commercial application of PEM water electrolysis technology. Summary of the invention:

[0003] The purpose of the present invention is to provide a carrier-stabilized ruthenium-based catalyst and a preparation method and application thereof.

[0004] The present invention is achieved through the following technical solutions:

[0005] A carrier-stabilized ruthenium-based catalyst comprises a non-noble metal oxide carrier and a ruthenium-based oxygen-evolving active component loaded thereon, wherein the ruthenium-based oxygen-evolving active component is a mixed crystal phase ruthenium-based oxide, wherein the ruthenium-based oxide comprises at least one of ruthenium dioxide and ruthenium trioxide, and a heterojunction structure exists between the non-noble metal oxide carrier and the mixed crystal phase ruthenium-based oxide, and the catalyst has a composite structure of a ruthenium-based oxide microcrystalline structure and a heterojunction structure.

[0006] Preferably, the ruthenium-based oxide is RuO 2 And Ru 2 O 3 The activity and stability of the catalyst are effectively enhanced by utilizing the combination of two valence states of ruthenium in the ruthenium-based oxide.

[0007] The particle size of the ruthenium-based catalyst is 2-15 nm.

[0008] The non-precious metal oxide carrier has high stability and electrical conductivity, and is selected from at least one of antimony tin oxide, titanium oxide, zirconium oxide, tungsten oxide, tin dioxide, cerium oxide, niobium pentoxide, and tantalum pentoxide; the solubility of the above-mentioned carrier in water and acidic environment is very low, so it can avoid the carrier being eluted from the catalyst particles during actual application, resulting in damage to the catalyst activity, and the above-mentioned carrier and the mixed crystal phase ruthenium-based oxide can spontaneously form a heterojunction structure, effectively improving the activity and stability of the catalyst.

[0009] The loading amount of the ruthenium-based oxide in the catalyst can be selected according to actual needs. Based on the total weight of the catalyst, the loading amount of the ruthenium-based oxide in the catalyst is 10-90%.

[0010] The preparation method of the catalyst comprises the following steps:

[0011] a. Mix the ruthenium precursor salt, the non-precious metal oxide carrier, water and the low-boiling point alcohol solvent and stir at a constant temperature; the constant temperature is 60°C-90°C, and the stirring time is ≥10 minutes;

[0012] b. After adding sodium nitrate and water to the solution obtained in step a, stirring and mixing at room temperature, the solution was dried to obtain a solid mixture, and ground into a powder;

[0013] c. The powder obtained in step b is continuously sintered at two different temperatures for a certain period of time, the first sintering temperature is 100-175°C, and the sintering time is ≥10 minutes; the second sintering temperature is 250-850°C, and the sintering time is ≥10 minutes, and then annealed to 100°C, taken out, cooled to room temperature, and ground;

[0014] d. The sintered material obtained in step c is added into pure water for washing, and in order to avoid the introduction of impurities, the catalyst particles are separated and dried.

[0015] Preferably, the ruthenium precursor salt includes at least one of ruthenium trichloride, ruthenium tetrachloride, ruthenium nitrosyl nitrate and ruthenium acetate.

[0016] The low boiling point alcohol solvent includes at least one of isopropanol, ethanol, methanol and tert-butanol.

[0017] The constant temperature stirring in step a can be carried out in a water bath at a temperature of 60°C-90°C. This treatment can make the ruthenium precursor salt and the carrier mixed evenly and tightly combined, so that after post-treatment, the ruthenium-based oxide can be evenly and stably loaded on the carrier and form a heterojunction structure, effectively enhancing electronic conduction and electrical conductivity.

[0018] Preferably, the drying temperature in step b is 60° C.-90° C., within which temperature range the mixed powder can be dried quickly. To avoid the introduction of impurities, the drying can be performed in a vacuum drying device.

[0019] Step c is to continuously sinter the powder obtained in step b at two different temperatures for a certain period of time, wherein the second stage sintering temperature is 250°C-850°C for heat treatment for ≥10min, and the heat treatment can make sodium nitrate and ruthenium precursor salt melt at high temperature to form ruthenium nitrate, and decompose ruthenium nitrate into a ruthenium-based oxide precursor with small primary particles, large specific surface area, high activity and strong stability uniformly loaded on the carrier. Preferably, the temperature of the second stage sintering is 250-350°C.

[0020] Exemplarily, the temperature of the second sintering stage is any value among 250℃, 350℃, 450℃, 550℃, 650℃, 750℃, 850℃ or between any two values, and the time is any value among 10min, 30min, 60min, 90min, 100min, 120min or between any two values.

[0021] The present invention improves the catalytic activity by utilizing the structural defects and oxygen vacancies of the non-precious metal oxide support, and at the same time strengthens the combination of the non-precious metal oxide support and the ruthenium precursor salt by treating the ruthenium precursor salt and the non-precious metal oxide support with low-boiling point alcohols and performing two-stage continuous temperature sintering, thereby constructing a heterojunction and a microcrystalline structure between the non-precious metal oxide support and the mixed crystal phase ruthenium-based oxide to achieve catalyst stabilization. Thanks to this unique morphology, the catalyst of the present invention exhibits very excellent OER performance and long-term stability. Therefore, the catalyst obtained by the present invention can be used not only in the electrode of a water electrolysis device, but also in a thin film and a thin film-electrode assembly coated with the catalyst in the water electrolysis device.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1) The present invention utilizes the structural defects and oxygen vacancies of the non-precious metal oxide carrier to make the catalyst have more active sites, thereby improving the catalytic activity.

[0024] 2) The present invention treats the ruthenium precursor salt and the non-precious metal oxide carrier with low-boiling alcohols and sinters at two continuous temperatures, thereby strengthening the combination of the non-precious metal oxide carrier and the ruthenium precursor salt, and the catalyst finally obtained has a microcrystalline structure and a heterojunction structure. A heterojunction structure refers to an interface structure composed of two or more different materials or crystal structures, which differ in physical and chemical properties. The heterojunction structure can improve the stability of the catalyst through various mechanisms such as the adjustment of the electronic structure, the increase of active sites, the improvement of corrosion resistance, and the synergistic effect between interfaces. The microcrystalline structure is a crystal structure with a small grain size, a large specific surface area, and outstanding surface activity. The catalyst activity is improved through various mechanisms, including adjusting electronic properties, increasing active sites, improving stability, optimizing intermediate adsorption free energy, optimizing structural properties, and forming a catalytic-conductive heterojunction interlocking structure. These factors work together to enable the microcrystalline catalyst to exhibit excellent catalytic performance in electrocatalysis. The catalyst of the present invention is a composite structure of a microcrystalline structure and a heterojunction structure. A heterojunction structure exists between a non-precious metal oxide carrier and a mixed crystal phase ruthenium-based oxide, which can produce lattice strain and adjustment of the electronic structure at the interface, thereby enhancing the chemical and structural stability of the catalyst. This unique structural design helps to inhibit the loss of active sites, prevent catalyst surface poisoning, and improve charge transfer efficiency, thereby providing more stable performance and longer service life during the electrocatalytic process.

[0025] In summary, the present invention improves the catalytic activity by utilizing the structural defects and oxygen vacancies of the non-precious metal oxide support, and at the same time strengthens the bonding between the non-precious metal oxide support and the ruthenium precursor salt by treating the ruthenium precursor salt and the non-precious metal oxide support with low-boiling point alcohols and performing two-stage continuous temperature sintering, thereby constructing a heterojunction and a microcrystalline structure between the non-precious metal oxide support and the mixed crystal phase ruthenium-based oxide, thereby achieving catalyst stabilization. Thanks to this unique morphology, the catalyst of the present invention exhibits very excellent OER performance and long-term stability. Description of the drawings:

[0026] Figure 1 is the XRD pattern of the catalyst prepared in Example 1;

[0027] Figure 2 This is a low-magnification TEM image of the catalyst prepared in Example 1;

[0028] Figure 3 This is a high-magnification TEM image of the catalyst prepared in Example 1;

[0029] Figure 4 This is a comparison diagram of the overpotentials of the catalysts prepared in Example 1 and Comparative Example 1;

[0030] Figure 5XPS spectra of the catalysts prepared in Example 1 and Comparative Example 1: fitting spectra of Ru 3p and Sn 3d;

[0031] Figure 6 The catalyst prepared in Example 1 and Comparative Example 1 is 10 mA cm -2 Constant current timing diagram when .

[0032] Figure 7 The voltammogram of the catalyst prepared in Example 1 in a PEM electrolyzer.

[0033] Figure 8 This is a timing constant current diagram of the catalyst prepared in Example 1 in a PEM electrolyzer. Specific implementation method:

[0034] The following is a further description of the present invention, rather than a limitation of the present invention.

[0035] Embodiment 1:

[0036] In the first step, 130 mg of antimony tin oxide and 351 mg of ruthenium trichloride were dissolved in 4.2 g of isopropanol and 8.4 ml of deionized water, and stirred in a constant temperature water bath at 80° C. for 1 h to obtain a uniform solution.

[0037] In the second step, 14.95 g of sodium nitrate and 30 ml of deionized water were added to the solution obtained in the first step, and the mixture was stirred for 1 h. The resulting solution was dried in an oven at 80° C. for 12 h to obtain a dry flaky solid mixture, which was fully ground under a drying lamp.

[0038] In the third step, the ground material was placed in a muffle furnace and heated at 5°C / min. After reaching 150°C, it was kept warm for 1h for the first stage of sintering. Then, the temperature was raised at 5°C / min. After reaching 300°C, it was kept warm for 1h for the second stage of sintering. Then, it was annealed to 100°C and taken out. After cooling to room temperature, it was fully ground and added with 30ml of deionized water, stirred for 1h and centrifuged, and dried at 60°C for 12h to obtain a catalyst, which was recorded as ATO / RuO x -300. Among them, Figure 1 ATO / RuO prepared in Example 1 x The XRD pattern of the catalyst Figure 1 The formation of the target catalyst can be clearly seen in the figure. Figure 2 ATO / RuO prepared in Example 1 x Low magnification TEM image of the catalyst, according to Figure 2 It can be seen that ATO / RuO x The catalyst particle size is uniform. Figure 3 ATO / RuO prepared in Example 1 x High magnification TEM image of the catalyst. Figure 3 It can be seen that the particle size of the ruthenium-based oxide is uniform and is about 5-15 nm, and the ruthenium-based oxide is evenly distributed on the carrier ATO. Figure 5 This is the XPS spectrum of the catalyst prepared in Example 1. It can be seen from the figure that the ruthenium-based oxygen evolution active component is a ruthenium-based oxide in a mixed crystal phase, and the ruthenium-based oxide includes ruthenium dioxide and ruthenium trioxide.

[0039] Example 2

[0040] Referring to Example 1, the only difference is that the temperature of the second stage sintering in the third step is different. The second stage sintering is calcined at 250°C for 1h to obtain ATO / RuO x -250.

[0041] Example 3

[0042] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 350°C for 1h to obtain ATO / RuO x -350.

[0043] Example 4

[0044] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 450°C for 1h to obtain ATO / RuO x -450.

[0045] Example 5

[0046] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 550°C for 1h to obtain ATO / RuO x -550.

[0047] Example 6

[0048] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 650°C for 1h to obtain ATO / RuO x -650.

[0049] Example 7

[0050] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 750°C for 1h to obtain ATO / RuO x -750.

[0051] Example 8

[0052] Refer to Example 1, the only difference is that in the third step, the second stage is sintered at 850°C for 1h to obtain ATO / RuO x -850.

[0053] Example 9

[0054] Referring to Example 1, the only difference is that titanium oxide is used instead of antimony tin oxide to obtain TiO 2 / RuO x -300.

[0055] Comparative Example 1

[0056] Refer to Example 1, the only difference is that no ATO carrier is added, and a ruthenium-based oxide catalyst is used.

[0057] Test Example 1

[0058] The electrochemical test was carried out on a Shanghai Chenhua CHI660E electrochemical station and a glassy carbon electrode. The electrochemical performance tests of the catalysts prepared in each embodiment and each comparative example were mainly linear sweep (LSV) test, chronopotentiometry, etc. All electrode potentials in the experiment were normalized using a reversible hydrogen electrode (RHE).

[0059] 1) Preparation of working electrode

[0060] Weigh 6.5 mg of catalyst using an electronic balance and add it to a 5 ml centrifuge tube. Pipette 2 ml of the prepared dispersion (500 ml isopropanol, 1490 ml water and 10 ml 5 wt% Nafion solution). Place the mixed solution in a cell crusher for ultrasonic dispersion for 20 min to obtain a uniform catalyst ink. Use a 10 uL pipette to measure 5 uL of the catalyst ink and drop it evenly on the pre-polished and cleaned gold electrode (area 0.071 cm 2 ) so that the ink does not overflow and is evenly spread on the electrode surface. Wait for it to dry naturally to form a catalytic layer, and then you can get a working electrode.

[0061] 2) Electrochemical performance test

[0062] Linear sweep voltammetry: In order to evaluate the OER electrocatalytic performance of the catalyst materials and their performance in the reaction process, anodic polarization measurements were performed and the linear sweep voltammetry (LSV) results were used for judgment. The LSV scan rate was 10 mV·s -1 , the scanning range is 1.05~1.65vs RHE.

[0063] The results are as follows: the overpotential of Example 1 is 188mV, the overpotential of Example 2 is 195mV, the overpotential of Example 3 is 207mV, the overpotential of Example 4 is 217mV, the overpotential of Example 5 is 203mV, the overpotential of Example 6 is 247mV, the overpotential of Example 7 is 244mV, the overpotential of Example 8 is 221mV, the overpotential of Example 9 is 245mV, and the overpotential of Comparative Example 1 is 248mV. Figure 4 This is a comparison diagram of the overpotentials of the catalysts prepared in Example 1 and Comparative Example 1.

[0064] according to Figure 4 It can be seen that, compared with Comparative Example 1, each embodiment provided in the present application can effectively reduce the overpotential of the catalyst, that is, the embodiments provided in the present application can effectively improve the activity of the catalyst.

[0065] 3) Constant current timing durability test: In order to study the stability of the prepared catalyst in an acidic electrochemical environment, the catalysts obtained in Example 1 and Comparative Example 1 were subjected to a constant current timing durability test. -2 The durability is determined by observing the voltage change by the current. Figure 6 shown. Figure 6 The catalyst prepared in Example 1 and Comparative Example 1 was -2 Voltage comparison chart, according to Figure 6 It can be seen that compared with the catalyst of Comparative Example 1, the catalyst of Example 1 has better stability. Figure 7 The voltammogram of the catalyst prepared in Example 1 in a PEM electrolyzer shows excellent activity. Figure 8 This is a timed constant current diagram of the catalyst prepared in Example 1 in a PEM electrolyzer, which has excellent stability.

[0066] In summary, the catalyst for water electrolysis provided in the present application has both good activity and stability.

[0067] The above are only specific embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A carrier-stabilized ruthenium-based catalyst, characterized in that: The catalyst comprises a non-noble metal oxide carrier and a ruthenium-based oxygen-evolving active component loaded thereon, wherein the ruthenium-based oxygen-evolving active component is a mixed crystal phase ruthenium-based oxide, wherein the ruthenium-based oxide comprises at least one of ruthenium dioxide and ruthenium trioxide, and a heterojunction structure exists between the non-noble metal oxide carrier and the mixed crystal phase ruthenium-based oxide, and the catalyst has a composite structure of a ruthenium-based oxide microcrystalline structure and a heterojunction structure.

2. The catalyst according to claim 1, characterized in that The particle size of the ruthenium-based catalyst is 2-15 nm.

3. The catalyst according to claim 1, characterized in that The non-noble metal oxide carrier is selected from at least one of antimony tin oxide, titanium oxide, zirconium oxide, tungsten oxide, tin dioxide, cerium oxide, niobium pentoxide and tantalum pentoxide.

4. The catalyst according to claim 1, characterized in that The loading amount of the ruthenium-based oxide in the catalyst is 10-90% based on the total weight of the catalyst.

5. The method for preparing the catalyst according to claim 1, characterized in that: The following steps are involved: a. Mix the ruthenium precursor salt, the non-precious metal oxide carrier, water and the low-boiling point alcohol solvent and stir at a constant temperature; the constant temperature is 60°C-90°C, and the stirring time is ≥10 minutes; b. After adding sodium nitrate and water to the solution obtained in step a, stirring and mixing at room temperature, the solution was dried to obtain a solid mixture, and ground into a powder; c. The powder obtained in step b is continuously sintered at two different temperatures for a certain period of time, the first sintering temperature is 100-175°C, and the sintering time is ≥10 minutes; the second sintering temperature is 250-850°C, and the sintering time is ≥10 minutes, and then annealed to 100°C, taken out, cooled to room temperature, and ground; d. The sintered material obtained in step c is added into pure water for cleaning, separation and drying to obtain catalyst particles.

6. The method for preparing the catalyst according to claim 5, characterized in that: The ruthenium precursor salt includes at least one of ruthenium trichloride, ruthenium tetrachloride, ruthenium nitrosyl nitrate and ruthenium acetate; the low boiling point alcohol solvent includes at least one of isopropanol, ethanol, methanol and tert-butanol.

7. The method for preparing a catalyst according to claim 5, characterized in that: Step a: constant temperature stirring is carried out in a water bath, and the water bath temperature is 60°C-90°C.

8. The method for preparing the catalyst according to claim 5, characterized in that: The drying temperature in step b is 60° C.-90° C., and the drying is carried out in a vacuum drying device.

9. The method for preparing a catalyst according to claim 5, characterized in that: The temperature of the second sintering stage in step c is 250-350°C.

10. Use of the catalyst according to claim 1, characterized in that: The invention is applied to electrodes of a water electrolysis device, or to a membrane and a membrane-electrode assembly coated with the catalyst in a water electrolysis device.

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