An iridium-ruthenium-tin composite catalyst, its preparation method and application

Abstract

This disclosure relates to an iridium-ruthenium-tin composite catalyst, its preparation method, and its applications. The iridium-ruthenium-tin composite catalyst comprises iridium, ruthenium, and tin. The XRD pattern of the iridium-ruthenium-tin composite catalyst shows only amorphous peaks between 25 and 40°. The iridium-ruthenium-tin composite catalyst of this disclosure exhibits higher catalytic activity than commercial iridium oxide catalysts, and significantly reduces the amount of precious metals used, thus lowering costs and making it highly valuable for practical applications.

Description

Technical Field

[0001] This disclosure relates to the fields of hydrogen energy and chemical engineering, specifically to an iridium-ruthenium-tin composite catalyst, its preparation method, and its application. Background Technology

[0002] Compared to alkaline water electrolysis, proton exchange membrane (PEM) water electrolysis for hydrogen production offers advantages such as faster response, higher current density, wider operating range, and higher hydrogen purity. It holds unparalleled advantages, particularly in the application of renewable energy power generation followed by water electrolysis for hydrogen production, making it a primary method for obtaining green hydrogen in the future. The anode catalyst is one of the key materials in PEM water electrolysis for hydrogen production and is the main rate-controlling step. Currently, commercial PEM water electrolysis devices primarily use iridium oxide or iridium black catalysts. The precious metal iridium is expensive (approximately 1000 RMB / g), and its concentration is typically 1-2 mg / cm³. 2 Therefore, reducing the amount of iridium used in the anode is one of the key breakthroughs for the large-scale application of PEM water electrolysis. There are two strategies to reduce the amount of iridium used: one is to improve the intrinsic electrochemical activity of the catalyst, so that only a small amount of catalyst is needed to achieve the same performance; the other is to improve the utilization rate of the active components. Summary of the Invention

[0003] The purpose of this disclosure is to provide an iridium-ruthenium-tin composite catalyst, its preparation method, and its application. This iridium-ruthenium-tin composite catalyst has higher catalytic activity than commercial iridium oxide catalysts, and the amount of precious metal used is significantly reduced, resulting in lower costs and greater practical value.

[0004] To achieve the above objectives, the first aspect of this disclosure provides an iridium-ruthenium-tin composite catalyst, wherein the iridium-ruthenium-tin composite catalyst comprises iridium, ruthenium, and tin, and the XRD pattern of the iridium-ruthenium-tin composite catalyst shows only amorphous peaks between 25° and 40°.

[0005] Optionally, the O1s characteristic peak of the XPS spectrum of the iridium-ruthenium-tin composite catalyst includes the MO characteristic peak and the M-OH characteristic peak, and B0 as defined by the following formula (1) is any value between 0.4 and 0.5;

[0006] B0 = B1 / (B1 + B2) Equation (1);

[0007] Wherein, B1 is the peak area of ​​the M-OH characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst; B2 is the peak area of ​​the MO characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst.

[0008] Optionally, the BET specific surface area of ​​the iridium-ruthenium-tin composite catalyst is 60–80 m². 2 / g, with a particle size of 3-8nm.

[0009] Optionally, the chemical composition of the iridium-ruthenium-tin composite catalyst is Ir x Ru y Sn 1-x-y O2; where x is any value between 0.4 and 0.6, and y is any value between 0.1 and 0.2.

[0010] Optionally, the XRD pattern of the iridium-ruthenium-tin composite catalyst does not show diffraction peaks for IrO2, RuO2, and SnO2.

[0011] A second aspect of this disclosure provides a method for preparing an iridium-ruthenium-tin composite catalyst, the method comprising the following steps:

[0012] S1. An iridium source, a ruthenium source, a tin source, a complexing agent, and water are mixed, and the resulting mixture is reacted to obtain a first material; wherein the pH of the mixture is 5-9, and the complexing agent is selected from C4-C8 organic polybasic acids and soluble salts of C4-C8 organic polybasic acids;

[0013] S2. Separate the water from the first material to obtain the iridium-ruthenium-tin composite catalyst precursor;

[0014] S3. The iridium-ruthenium-tin composite catalyst precursor is calcined under an oxygen-containing atmosphere.

[0015] Optionally, step S1 includes the following steps:

[0016] S1-1. The iridium source, the first complexing agent and water are mixed for the first time and the pH is adjusted to 5-9, preferably 7-8, to obtain the first mixture;

[0017] S1-2, The ruthenium source, the second complexing agent and water are mixed for the second time and the pH is adjusted to 5-9, preferably 7-8, to obtain the second mixture;

[0018] S1-3. The tin source, the third complexing agent and water are mixed in a third mixture and the pH is adjusted to 5-9, preferably 7-8, to obtain the third mixture;

[0019] S1-4. The first mixture, the second mixture and the third mixture are mixed to obtain the mixture material.

[0020] Optionally, the iridium source is selected from one or more of chloroiridic acid and alkali metal salts of chloroiridic acid; preferably, the alkali metal salt of chloroiridic acid is selected from one or two of potassium chloroiridicate and sodium chloroiridicate.

[0021] The ruthenium source is a soluble salt of ruthenium, preferably one or both of ruthenium trichloride and ruthenium acetate;

[0022] The tin source is a soluble salt of tin and / or a soluble alkali metal stannate, preferably one or both of tin tetrachloride or sodium stannate.

[0023] Optionally, the first complexing agent, the second complexing agent, and the third complexing agent may be the same or different, and each may be independently selected from one or more of citric acid, tartaric acid, malic acid, succinic acid, sodium citrate, sodium tartrate, sodium malate, and sodium succinate.

[0024] Preferably, the molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5 to 2.5:1, more preferably 1.8 to 2.2:1;

[0025] Preferably, the molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1 to 2:1, more preferably 1.5 to 1.8:1;

[0026] Preferably, the molar ratio of the third complexing agent to the tin source (calculated as tin) is 2 to 3:1, more preferably 2.2 to 2.7:1.

[0027] Optionally, in step S1, the molar ratio of the iridium source (in terms of iridium), the tin source (in terms of tin), and the ruthenium source (in terms of ruthenium) is (2-6):(1-5):1.

[0028] Optionally, in step S1, the reaction conditions include: a temperature of 50–80°C, preferably 60–70°C; and a reaction time of 0.5–4 h, preferably 1–2 h.

[0029] Optionally, in step S1, the pH of the mixture is 7 to 8;

[0030] Optionally, a pH adjuster is added to adjust the pH of the mixture. Optionally, the pH adjuster is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and ammonia water.

[0031] Optionally, in step S3, the conditions for the calcination treatment include: a calcination temperature of 300–400°C, preferably 340–370°C; and a calcination time of 1–3 hours.

[0032] Optionally, the method further includes: washing the product obtained from the calcination treatment; the solvent used in the washing treatment is a mixed solution of alcohol and water, wherein the alcohol accounts for 10-95% by weight of the mixed solution, preferably 30-60% by weight;

[0033] Preferably, the alcohol is selected from one or more of methanol, ethanol, n-propanol and isopropanol.

[0034] The third aspect of this disclosure provides an iridium-ruthenium-tin composite catalyst prepared by the method described in the second aspect of this disclosure.

[0035] This fourth aspect of the disclosure provides the use of the iridium-ruthenium-tin composite catalyst described in the first and third aspects of the disclosure in hydrogen production by water electrolysis.

[0036] Through the above technical solution, this disclosure provides an iridium-ruthenium-tin composite catalyst, its preparation method, and its application. The iridium-ruthenium-tin composite catalyst contains amorphous oxides of iridium, ruthenium, and tin. Its XRD spectrum shows only amorphous peaks and no obvious crystallization diffraction peaks. When used as an anode catalyst for proton exchange membrane electrolysis of water to produce hydrogen, it has better stability than ruthenium catalysts, higher catalytic activity than commercial iridium oxide catalysts, and significantly reduces the amount of precious metals used, thus significantly reducing costs.

[0037] Furthermore, in the preparation process, this disclosure uses a complexing agent mixed with the iridium, ruthenium, and tin sources, which can improve the dispersion uniformity of the iridium, ruthenium, and tin sources in the mixed solution. Moreover, this disclosure uses C4-C8 organic polybasic acids and their soluble salts as complexing agents, which can prevent precipitation in the solution. The reaction process does not use strong corrosive solvents such as hydrochloric acid, and the preparation method is simple to operate and operates under mild conditions.

[0038] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is the XRD pattern of the catalyst in Example 1 of this disclosure.

[0041] Figure 2 This is the TEM image of the catalyst in Example 1 of this disclosure.

[0042] Figure 3 This is the O1s XPS spectrum of the catalyst in Example 1 of this disclosure. Detailed Implementation

[0043] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0044] The first aspect of this disclosure provides an iridium-ruthenium-tin composite catalyst, wherein the iridium-ruthenium-tin composite catalyst comprises iridium, ruthenium, and tin, and the XRD pattern of the iridium-ruthenium-tin composite catalyst shows only amorphous peaks between 25° and 40°.

[0045] The iridium-ruthenium-tin composite catalyst disclosed herein contains iridium, ruthenium, and tin. Its XRD pattern shows only amorphous peaks and no obvious crystallization diffraction peaks. When used as an anode catalyst for proton exchange membrane electrolysis of water to produce hydrogen, it exhibits higher catalytic activity than commercial iridium oxide catalysts, and the amount of precious metals used is significantly reduced, resulting in a significant reduction in cost.

[0046] In this disclosure, "peak pockets" in XRD spectra refer to other forms of bulges in XRD spectra besides the obvious and sharp characteristic peaks that are conventionally considered by those skilled in the art. "Peak pockets" generally have characteristics such as low intensity and large width.

[0047] According to one embodiment of this disclosure, the XRD pattern of the iridium-ruthenium-tin composite catalyst does not show diffraction peaks for IrO2, RuO2, and SnO2. In the iridium-ruthenium-tin composite catalyst provided by this disclosure, iridium, ruthenium, and tin exist in the form of amorphous oxides, and no diffraction peaks for IrO2, RuO2, and SnO2 appear in the XRD pattern.

[0048] According to one embodiment of this disclosure, the chemical composition of the iridium-ruthenium-tin composite catalyst is Ir x Ru y Sn 1-x- y O2; where x is any value between 0.4 and 0.6, and y is any value between 0.1 and 0.2. In this disclosure, the chemical composition of the catalyst was determined using X-ray fluorescence analysis (XRF analysis). The chemical composition of the catalyst is consistent with the feedstock addition ratio during preparation. The chemical composition described in this disclosure is for illustrative purposes only.

[0049] According to one embodiment of the present disclosure, the O1s characteristic peak of the XPS spectrum of the iridium-ruthenium-tin composite catalyst includes MO characteristic peak and M-OH characteristic peak, and B0 as defined by the following formula (1) is any value between 0.4 and 0.5;

[0050] B0 = B1 / (B1 + B2) Equation (1);

[0051] Wherein, B1 is the peak area of ​​the M-OH characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst; B2 is the peak area of ​​the MO characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst. The inventors found in experiments that when the B1 / (B1+B2) ratio of the iridium-ruthenium-tin composite catalyst is within the range of this embodiment, it can exhibit a lower overpotential and higher oxygen evolution activity.

[0052] According to one embodiment of this disclosure, the BET specific surface area of ​​the iridium-ruthenium-tin composite catalyst is 60-80 m². 2 / g, with a particle size of 3-8nm, preferably 4-6nm. In this disclosure, the particle size of the catalyst particles refers to the particle size measured by transmission electron microscopy. For example, "the particle size of the catalyst particles is 3-8nm" means that the particle size of each particle in the transmission electron microscopy spectrum of the catalyst particles is in the range of 3-8nm.

[0053] A second aspect of this disclosure provides a method for preparing an iridium-ruthenium-tin composite catalyst, the method comprising the following steps:

[0054] S1. An iridium source, a ruthenium source, a tin source, a complexing agent, and water are mixed, and the resulting mixture is reacted to obtain a first material; wherein the pH of the mixture is 5-9, and the complexing agent is selected from C4-C8 organic polybasic acids and soluble salts of C4-C8 organic polybasic acids;

[0055] S2. Separate the water from the first material to obtain the iridium-ruthenium-tin composite catalyst precursor;

[0056] S3. The iridium-ruthenium-tin composite catalyst precursor is calcined under an oxygen-containing atmosphere.

[0057] According to one embodiment of this disclosure, step S1 includes the following steps:

[0058] S1-1. The iridium source, the first complexing agent and water are mixed for the first time and the pH is adjusted to 5-9, preferably 7-8, to obtain the first mixture;

[0059] S1-2, The ruthenium source, the second complexing agent and water are mixed for the second time and the pH is adjusted to 5-9, preferably 7-8, to obtain the second mixture;

[0060] S1-3. The tin source, the third complexing agent and water are mixed in a third mixture and the pH is adjusted to 5-9, preferably 7-8, to obtain the third mixture;

[0061] S1-4. The first mixture, the second mixture, and the third mixture are mixed to obtain the mixture. The above-described embodiments can improve the uniformity of dispersion of the iridium, ruthenium, and tin sources in the mixture; at the same time, they can avoid precipitation in the solution; the reaction process does not use strong corrosive solvents such as hydrochloric acid, providing a simple and mild preparation method.

[0062] According to one embodiment of this disclosure, the iridium source is selected from one or more of chloroiridic acid and alkali metal salts of chloroiridic acid; preferably, the alkali metal salt of chloroiridic acid is selected from one or two of potassium chloroiridicate and sodium chloroiridicate; the chloroiridic acid may or may not contain water of crystallization, but generally contains water of crystallization (e.g., compounds represented by the formula H2IrCl6·6H2O); the ruthenium source is a soluble salt of ruthenium, preferably one or two of ruthenium trichloride and ruthenium acetate; the tin source is a soluble salt of tin and / or a soluble alkali metal stannate, preferably one or two of tin tetrachloride or sodium stannate.

[0063] According to one embodiment of this disclosure, the first complexing agent, the second complexing agent, and the third complexing agent may be the same or different, and each is independently selected from one or more of citric acid, tartaric acid, malic acid, succinic acid, sodium citrate, sodium tartrate, sodium malate, and sodium succinate.

[0064] Preferably, the molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5 to 2.5:1, more preferably 1.8 to 2.2:1;

[0065] Preferably, the molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1 to 2:1, more preferably 1.5 to 1.8:1;

[0066] Preferably, the molar ratio of the third complexing agent to the tin source (calculated as tin) is 2–3:1, more preferably 2.2–2.7:1. The above-described embodiments avoid precipitation in the solution and also contribute to a lower overpotential and higher oxygen evolution activity in the catalyst.

[0067] According to one embodiment of this disclosure, in step S1, the molar ratio of the iridium source (based on iridium), the tin source (based on tin), and the ruthenium source (based on ruthenium) is (2-6):(1-5):1. This embodiment is advantageous because it allows the catalyst to have a lower overpotential and higher oxygen evolution activity.

[0068] According to one embodiment of this disclosure, in step S1, the reaction conditions include: a temperature of 50–80°C, preferably 60–70°C; and a reaction time of 0.5–4 h, preferably 1–2 h.

[0069] Optionally, in step S1, the pH of the mixture is 7 to 8;

[0070] Optionally, a pH adjuster is added to adjust the pH of the mixture. Optionally, the pH adjuster is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and ammonia water.

[0071] According to one embodiment of this disclosure, in step S3, the conditions for the calcination treatment include: a calcination temperature of 300–400°C, preferably 340–370°C; and a calcination time of 1–3 hours.

[0072] According to one embodiment of this disclosure, the method further includes: washing the product obtained from the calcination treatment; the solvent used in the washing treatment is a mixed solution of alcohol and water, wherein the alcohol accounts for 10-95% by weight of the mixed solution, preferably 30-60% by weight; preferably, the alcohol is selected from one or more of methanol, ethanol, n-propanol and isopropanol. In the above preferred embodiments, the catalyst is more easily separated by centrifugation.

[0073] The third aspect of this disclosure provides an iridium-ruthenium-tin composite catalyst prepared by the method described in the second aspect of this disclosure.

[0074] This fourth aspect of the disclosure provides the use of the iridium-ruthenium-tin composite catalyst described in either the first or third aspect of the disclosure in hydrogen production via water electrolysis.

[0075] The present disclosure will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the scope of this disclosure in any way.

[0076] All raw materials used in the examples were obtained commercially and, unless otherwise specified, were of analytical grade. Chloroiridic acid or its alkali metal salt was prepared as an aqueous solution with a concentration of 0.182 mol / L, or a solution with a higher concentration could also be prepared.

[0077] Instruments, methods and conditions for TEM analysis: The high-resolution transmission electron microscope (HRTEM) used in this invention is model JEM-2100 (HRTEM) (Nippon Electron Ltd.), and the high-resolution transmission electron microscope test conditions are: accelerating voltage of 200kV.

[0078] The X-ray fluorescence spectrometer (XRF) model is Rigaku 3013. The X-ray fluorescence spectroscopy analysis test conditions are: scan time of 100s and atmosphere of air.

[0079] This disclosure describes the detection of elements on the surface of a material using X-ray photoelectron spectroscopy (XPS). The X-ray photoelectron spectroscopy instrument used is a VG Scientific ESCALab220i-XL model equipped with Avantage V5.926 software. The X-ray photoelectron spectroscopy analysis conditions are as follows: the excitation source is monochromatic AlKα X-rays, the power is 330W, and the basic vacuum during analysis is 3×10⁻⁶. -9mbar. In addition, the electron binding energy is corrected using the C1s peak (284.3 eV) of elemental carbon.

[0080] BET test method: In this disclosure, the pore structure properties of the sample were determined by a Quantachrome AS-6B analyzer, and the specific surface area of ​​the catalyst was obtained by the Brunauer-Emmett-Taller (BET) method.

[0081] X-ray diffraction (XRD) analysis was performed on a Shimadzu XRD-6000 X-ray diffractometer in Japan. The test conditions included: tube voltage 40 kV, tube current 40 mA, Cu target Kα radiation, and 2θ scan range of 5° to 80°.

[0082] The electrochemical workstation was a PARSTAT3000A-DX, and the rotating disk electrode was a 636A. A three-electrode system was used: a saturated calomel electrode as the reference electrode, a platinum sheet as the counter electrode, and a glassy carbon electrode as the working electrode. The electrolyte used under acidic conditions was a 0.5M H₂SO₄ solution. The catalyst to be tested was ultrasonically and uniformly dispersed in a mixed solution of isopropanol, water, and Nafion, and then dropped onto the surface of the glassy carbon electrode. After natural drying, the working electrode was obtained, with a catalyst loading of 0.38 mg / cm³. -2 The test temperature was 25℃. Before the test, oxygen was purged for 30 minutes to saturate the solution. The rotation speed was 2500 rpm. The linear polarization curve scan range was 1.2–1.5 V (vs RHE), and the scan rate was 5 mV / s. The stability test scan range was 1.26 V–1.56 V (vs RHE), the scan rate was 50 mV / s, and the number of scans was 10,000.

[0083] Example 1 Catalyst Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0084] (1) Take 20 mL (3.64 mmol) of chloroiridic acid aqueous solution and weigh 1.05 g (5.47 mmol) of citric acid. Mix them at room temperature and adjust the pH of the solution to between 7 and 8. The molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5:1.

[0085] (2) Weigh 0.13 g (0.62 mmol) of ruthenium trichloride and dissolve it in 5 ml of water. Weigh 0.12 g (0.62 mmol) of citric acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1:1.

[0086] (3) Weigh 0.48g (1.82mmol) of Na2SnO3·3H2O and dissolve it in 10ml of water. Weigh 0.87g (4.53mmol) of citric acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2.5:1. The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 6:3:1.

[0087] (4) After mixing the three solutions from steps (1) to (3), react them at 70°C for 1 hour.

[0088] (5) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0089] (6) After the catalyst is cooled, it is ground, spread evenly in a ceramic boat, and heated to 330°C at a heating rate of 2°C / min in air atmosphere, and held for 2 hours.

[0090] (7) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-1.

[0091] XRF analysis revealed that the chemical composition of CAT-1 is Ir. 0.6 Ru 0.1 Sn 0.3 The XRD pattern of O2 CAT-1 is as follows: Figure 1 As shown in the figure, only a weak amorphous peak appears around 25-40°. TEM analysis indicates that the particle size of CAT-1 is 3-5 nm.

[0092] Example 2 Catalyst Ir 0.5 Ru 0.1 Sn 0.4 O2 preparation

[0093] (1) Take 20 mL (3.64 mmol) of chloroiridic acid aqueous solution and weigh 1.05 g (5.47 mmol) of citric acid. Mix them at room temperature and adjust the pH of the solution to between 7 and 8. The molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5:1.

[0094] (2) Weigh 0.15 g (0.73 mmol) of ruthenium trichloride and dissolve it in 5 ml of water. Weigh 0.15 g (0.78 mmol) of citric acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1.1:1.

[0095] (3) Weigh 0.78g (2.91mmol) of Na2SnO3·3H2O and dissolve it in 10ml of water. Weigh 1.40g (7.29mmol) of citric acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2.5:1. The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 5:4:1.

[0096] (4) After mixing the three solutions from steps (1) to (3), react them at 70°C for 1 hour.

[0097] (5) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0098] (6) After the catalyst is cooled, it is ground, spread evenly in a ceramic boat, and heated to 330°C at a heating rate of 2°C / min in air atmosphere, and held for 2 hours.

[0099] (7) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-2.

[0100] XRF analysis revealed that the chemical composition of CAT-2 is Ir. 0.5 Ru 0.1 Sn 0.4 O2.

[0101] Example 3 Catalyst Ir 0.4 Ru 0.2 Sn 0.4 O2 preparation

[0102] (1) Take 20 mL (3.64 mmol) of chloroiridic acid aqueous solution and weigh 1.05 g (5.47 mmol) of citric acid. Mix them at room temperature and adjust the pH of the solution to between 7 and 8. The molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5:1.

[0103] (2) Weigh 0.38 g (1.83 mmol) of ruthenium trichloride and dissolve it in 5 ml of water. Weigh 0.36 g (1.88 mmol) of citric acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1:1.

[0104] (3) Weigh 0.97 g (3.64 mmol) of Na2SnO3·3H2O and dissolve it in 10 ml of water. Weigh 1.75 g (9.11 mmol) of citric acid. After mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2.5:1. The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 2:2:1.

[0105] (4) After mixing the three solutions from steps (1) to (3), react them at 70°C for 1 hour.

[0106] (5) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0107] (6) After the catalyst is cooled, it is ground, spread evenly in a ceramic boat, and heated to 330°C at a heating rate of 2°C / min in air atmosphere, and held for 2 hours.

[0108] (7) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-3.

[0109] XRF analysis revealed that the chemical composition of CAT-3 is Ir. 0.4 Ru 0.2 Sn 0.4 O2.

[0110] Example 4 Catalyst Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0111] The catalyst was prepared using the same method as in Example 1, except that:

[0112] (1) Take 20 mL (3.64 mmol) of potassium chloroiridate aqueous solution, weigh 0.82 g (5.47 mmol) of tartaric acid, stir and mix at room temperature, and adjust the pH of the solution to between 7 and 8; wherein the molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5:1;

[0113] (2) Weigh 0.15 g (0.62 mmol) of ruthenium acetate and dissolve it in 5 ml of water. Weigh 0.83 g (0.62 mmol) of malic acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1:1.

[0114] (3) Weigh 0.47 g (1.82 mmol) of tin tetrachloride and dissolve it in 10 ml of water. Weigh 0.53 g (4.53 mmol) of succinic acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2.5:1. The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 6:3:1.

[0115] (4) After mixing the three solutions from steps (1) to (3), react them at 70°C for 1 hour.

[0116] (5) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0117] (6) After the catalyst is removed and cooled, it is ground, spread evenly in a ceramic boat, heated to 380°C at a heating rate of 2°C / min in air atmosphere, and held for 1 hour.

[0118] (7) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-4.

[0119] XRF analysis revealed that the chemical composition of CAT-4 is Ir. 0.6 Ru 0.1 Sn 0.3 O2.

[0120] Example 5 Catalyst Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0121] The same preparation method as in Example 1 was used, except that:

[0122] The amount of citric acid weighed in step (1) is 1.40 g (7.29 mmol); wherein the molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 2:1;

[0123] The amount of citric acid weighed in step (2) is 0.20 g (1.04 mmol); wherein the molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1.7:1;

[0124] The calcination conditions were adjusted to: calcination at a heating rate of 2℃ / min to 350℃ for 1 hour. The remaining process was the same as in Example 1. The resulting catalyst product was designated CAT-5.

[0125] XRF analysis revealed that the chemical composition of CAT-5 is Ir. 0.6 Ru 0.1 Sn 0.3 O2.

[0126] Example 6 Catalyst Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0127] The same preparation method as in Example 4 was used, except that:

[0128] (1) Take 20 mL (3.64 mmol) of potassium chloroiridate aqueous solution, weigh 0.55 g (3.64 mmol) of tartaric acid, stir and mix at room temperature, and adjust the pH of the solution to between 7 and 8; wherein the molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1:1;

[0129] (2) Weigh 0.15 g (0.62 mmol) of ruthenium acetate and dissolve it in 5 ml of water. Weigh 0.42 g (0.31 mmol) of malic acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 0.5:1.

[0130] (3) Weigh 0.47 g (1.82 mmol) of tin tetrachloride and dissolve it in 10 ml of water. Weigh 0.32 g (2.73 mmol) of succinic acid. After stirring and mixing at room temperature, adjust the pH of the solution to between 7 and 8. The molar ratio of the third complexing agent to the tin source (calculated as tin) is 1.5:1. The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 6:3:1.

[0131] (4) After mixing the three solutions from steps (1) to (3), react them at 70°C for 1 hour.

[0132] (5) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0133] (6) After the catalyst is removed and cooled, it is ground, spread evenly in a ceramic boat, heated to 380°C at a heating rate of 2°C / min in air atmosphere, and held for 1 hour.

[0134] (7) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-6.

[0135] XRF analysis revealed that the chemical composition of CAT-6 is Ir 0.6 Ru 0.1 Sn 0.3 O2.

[0136] Example 7Ir 0.3 Ru 0.3 Sn 0.4 O2 preparation

[0137] The same preparation method as in Example 4 was used, except that:

[0138] The molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 1:1.3:1. In (1), 10 mL (1.82 mmol) of potassium chloroiridate aqueous solution was weighed; in (2), 0.43 g (1.82 mmol) of ruthenium acetate was weighed; and in (3), 0.63 g (2.42 mmol) of tin tetrachloride was weighed. The resulting catalyst product is designated CAT-7.

[0139] XRF analysis revealed that the chemical composition of CAT-7 is Ir. 0.3 Ru 0.3 Sn 0.4 O2.

[0140] Example 8Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0141] The same preparation method as in Example 4 was used, except that:

[0142] The calcination conditions in step (6) were: calcination temperature of 450℃ and reaction time of 0.5h. The resulting catalyst product was designated as CAT-8.

[0143] XRF analysis revealed that the chemical composition of CAT-8 is Ir. 0.6 Ru 0.1 Sn 0.3 O2.

[0144] Example 9Ir 0.6 Ru 0.1 Sn0.3 O2 preparation

[0145] The same preparation method as in Example 4 was used, except that:

[0146] In steps (1), (2), and (3), the pH of the solution was adjusted to 9. The resulting catalyst product was denoted as CAT-9.

[0147] XRF analysis revealed that the chemical composition of CAT-9 is Ir. 06 Ru 01 Sn 03 O2.

[0148] Example 10Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0149] (1) Take 20 mL (3.64 mmol) of chloroiridium acid aqueous solution, dissolve 0.13 g (0.62 mmol) of ruthenium trichloride in 5 mL of water, dissolve 0.48 g (1.82 mmol) of Na2SnO3·3H2O in 10 mL of water, weigh 2.04 g (10.32 mmol) of citric acid, stir and mix at room temperature, and adjust the pH of the solution to between 7 and 8; the molar ratio of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) is 6:3:1.

[0150] (2) React the mixed solution from step (1) at 70°C for 1 hour;

[0151] (3) After cooling, spin dry at 70℃ and dry in a 120℃ oven for 8 hours;

[0152] (4) After the catalyst is cooled, it is ground, spread evenly in a ceramic boat, and heated to 330°C at a heating rate of 2°C / min in air atmosphere, and held for 2 hours.

[0153] (5) Cool to room temperature, add a certain amount of deionized water, ultrasonically wash, centrifuge (10000 rpm, 10 min), then wash with a 1:1 mixture of ethanol and water, centrifuge 3 times (pH test paper shows neutral), put the centrifuge tube containing the catalyst into a forced-air drying oven (60℃) and dry for 12 h. The obtained catalyst product is recorded as CAT-10.

[0154] XRF analysis revealed that the chemical composition of CAT-10 is Ir. 0.6 Ru 0.1 Sn 0.3 O2.

[0155] Comparative Example 1

[0156] A commercial iridium dioxide catalyst was used, purchased from Sigma-Aldrich, product number 206237, denoted as D1.

[0157] Comparative Example 2: Catalyst Ir 0.6 Ru 0.1 Sn 0.3 O2 preparation

[0158] The same preparation method as in Example 1 was used, except that:

[0159] No citric acid complexing agent was added in steps (1) to (3), and the other processes were the same as in Example 1; the resulting catalyst product was denoted as D2.

[0160] XRF analysis revealed that the chemical composition of D2 is Ir. 06 Ru 01 Sn 03 O2.

[0161] Test case

[0162] The catalyst particle size, BET specific surface area, B0(M-OH / (M-OH+MO)), and electrochemical performance test data (initial overpotential, mV, denoted as G1; final overpotential, mV, denoted as G2; test current density 10 mA / cm²) of the products obtained in the above examples and comparative examples were used. 2 Initial mass-to-specific activity of the catalyst at 1.45V vs. RHE, A / g (Ir+Ru) (denoted as M) are listed in Table 1 below.

[0163] Table 1

[0164]

[0165]

[0166] According to the data in Table 1:

[0167] Compared with catalysts D1 to D2 in Comparative Examples 1 and 2, the catalysts CAT-1 to CAT-10 prepared by the method provided in this disclosure have larger B0 values, indicating that the surface M-OH content of CAT-1 to CAT-10 is higher; the overpotential G1 is lower and the specific activity M is higher, indicating that the oxygen evolution activity of CAT-1 to CAT-10 is higher; the catalysts prepared in this disclosure use less precious metal and reduce cost.

[0168] Furthermore, compared to D1 (existing commercial iridium dioxide catalysts), the catalyst provided in this disclosure can effectively reduce the amount of precious metal iridium used. It significantly improves the oxygen evolution activity of the catalyst while maintaining relatively low stability reduction.

[0169] Compared with D2 (without adding a complexing agent during preparation), the particle size of CAT-1 to CAT-10 is significantly smaller than that of D2, indicating that the addition of a complexing agent during the preparation process can effectively improve the dispersion of raw materials and reduce the particle size of catalyst particles.

[0170] A comparison between CAT-4 and CAT-6 reveals that, within the range of the molar ratios of the first complexing agent to the iridium source (calculated as iridium), the second complexing agent to the ruthenium source (calculated as ruthenium), and the third complexing agent to the tin source (calculated as tin) disclosed in this invention, CAT-4 has a larger specific surface area, smaller particle size, lower overpotential G1, and higher specific activity M, indicating that CAT-4 has higher oxygen evolution activity.

[0171] A comparison between CAT-4 and CAT-7 reveals that, within the range of molar ratios of the iridium source (calculated as iridium), the tin source (calculated as tin), and the ruthenium source (calculated as ruthenium) disclosed in this invention, CAT-4 has a smaller particle size, a lower overpotential G1, and a higher specific activity M, indicating that CAT-4 has higher oxygen evolution activity.

[0172] A comparison between CAT-4 and CAT-8 shows that, within the calcination temperature and calcination time range disclosed in this paper, CAT-4 has a larger B0 value, smaller particle size, lower overpotential G1, and higher specific activity M, indicating that CAT-4 has higher oxygen evolution activity.

[0173] A comparison between CAT-4 and CAT-9 shows that, within the preferred pH range of this disclosure, CAT-4 has a smaller particle size, a lower overpotential G1, and a higher specific activity M, indicating that CAT-4 has higher oxygen evolution activity.

[0174] A comparison between CAT-1 and CAT-10 shows that, in the preferred material mixing order of this disclosure, CAT-1 has a smaller particle size, higher specific surface area, lower overpotential G1, and higher specific activity M, indicating that CAT-1 has higher oxygen evolution activity.

[0175] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0176] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0177] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An iridium-ruthenium-tin composite catalyst, characterized in that, The iridium-ruthenium-tin composite catalyst contains iridium, ruthenium, and tin elements, and the XRD pattern of the iridium-ruthenium-tin composite catalyst only shows amorphous peaks between 25° and 40°. The XPS spectrum of the iridium-ruthenium-tin composite catalyst contains MO characteristic peaks and M-OH characteristic peaks in the O1s peaks, and B0 as defined by the following formula (1) is any value between 0.4 and 0.5; B0 = B1 / (B1+B2) Equation (1); Wherein, B1 is the peak area of ​​the M-OH characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst; B2 is the peak area of ​​the MO characteristic peak in the XPS spectrum of the iridium-ruthenium-tin composite catalyst. The chemical composition of the iridium-ruthenium-tin composite catalyst is Ir x Ru y Sn 1-x-y O2; where x is any value between 0.4 and 0.6, and y is any value between 0.1 and 0.

2.

2. The iridium-ruthenium-tin composite catalyst according to claim 1, wherein, The BET specific surface area of ​​the iridium-ruthenium-tin composite catalyst is 60-80 m². 2 / g, with a particle size of 3~8nm.

3. The iridium-ruthenium-tin composite catalyst according to claim 1, wherein, The XRD pattern of the iridium-ruthenium-tin composite catalyst does not show diffraction peaks for IrO2, RuO2, and SnO2.

4. A method for preparing the iridium-ruthenium-tin composite catalyst according to any one of claims 1 to 3, characterized in that, The method includes the following steps: S1. An iridium source, a ruthenium source, a tin source, a complexing agent, and water are mixed, and the resulting mixture is reacted to obtain a first material; wherein the pH of the mixture is 5-9, and the complexing agent is selected from C4-C8 organic polybasic acids and soluble salts of C4-C8 organic polybasic acids; S2. Separate the water from the first material to obtain the iridium-ruthenium-tin composite catalyst precursor; S3. The iridium-ruthenium-tin composite catalyst precursor is calcined in an oxygen-containing atmosphere; In step S1, the molar ratio of the iridium source (in terms of iridium), the tin source (in terms of tin), and the ruthenium source (in terms of ruthenium) is (2~6):(1~5):

1. In step S3, the conditions for the calcination treatment include: calcination temperature of 300~380℃; and calcination time of 1~3h.

5. The method according to claim 4, wherein, Step S1 includes the following steps: S1-1. The iridium source, the first complexing agent and water are mixed in the first mixture and the pH is adjusted to 5-9 to obtain the first mixture; S1-2, The ruthenium source, the second complexing agent, and water are mixed for the second time and the pH is adjusted to 5-9 to obtain the second mixture; S1-3. The tin source, the third complexing agent and water are mixed in a third mixture and the pH is adjusted to 5-9 to obtain a third mixture; S1-4. The first mixture, the second mixture and the third mixture are mixed to obtain the mixture material.

6. The method according to claim 5, wherein, Step S1 includes the following steps: S1-1. The iridium source, the first complexing agent and water are mixed and the pH is adjusted to 7-8 to obtain a first mixture; S1-2, The ruthenium source, the second complexing agent, and water are mixed for the second time and the pH is adjusted to 7-8 to obtain the second mixture; S1-3. The tin source, the third complexing agent and water are mixed in a third mixture and the pH is adjusted to 7-8 to obtain a third mixture; S1-4. The first mixture, the second mixture and the third mixture are mixed to obtain the mixture material.

7. The method according to claim 4, wherein, The iridium source is selected from one or more of chloroiridic acid and alkali metal salts of chloroiridic acid; The ruthenium source is a soluble salt of ruthenium; The tin source is a soluble salt of tin and / or a soluble alkali metal stannate.

8. The method according to claim 7, wherein, The alkali metal salt of chloroiridate is selected from one or two of potassium chloroiridate and sodium chloroiridate; The ruthenium source is one or both of ruthenium trichloride and ruthenium acetate; The tin source is one or both of tin tetrachloride and sodium stannate.

9. The method according to claim 5, wherein, The first complexing agent, the second complexing agent, and the third complexing agent may be the same or different, and each is independently selected from one or more of citric acid, tartaric acid, malic acid, succinic acid, sodium citrate, sodium tartrate, sodium malate, and sodium succinate. The molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.5~2.5:1; The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1~2:1; The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2-3:

1.

10. The method according to claim 9, wherein, The molar ratio of the first complexing agent to the iridium source (calculated as iridium) is 1.8~2.2:1; The molar ratio of the second complexing agent to the ruthenium source (calculated as ruthenium) is 1.5~1.8:1; The molar ratio of the third complexing agent to the tin source (calculated as tin) is 2.2~2.7:

1.

11. The method according to claim 4, wherein, In step S1, the reaction conditions include: a temperature of 50~80℃ and a reaction time of 0.5~4h; In step S1, the pH of the mixture is 7-8; A pH adjuster is added to adjust the pH of the mixture, wherein the pH adjuster is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, and ammonia water.

12. The method according to claim 4, wherein, In step S1, the reaction conditions include: a temperature of 60~70℃ and a reaction time of 1~2h.

13. The method according to claim 4, wherein, In step S3, the conditions for the calcination treatment include: a calcination temperature of 340~370℃.

14. The method according to claim 4, wherein, The method further includes: washing the product obtained from the calcination treatment; the solvent used in the washing treatment is a mixed solution of alcohol and water, wherein the alcohol accounts for 10-95% by weight of the mixed solution. The alcohol is selected from one or more of methanol, ethanol, n-propanol, and isopropanol.

15. The method according to claim 14, wherein, The alcohol accounts for 30-60% by weight of the mixed solution.

16. Use of the iridium-ruthenium-tin composite catalyst according to any one of claims 1 to 3 in the electrolysis of water to produce hydrogen.

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