Iridium-doped bimetallic sulfide catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic electrochemistry, in particular to an iridium-doped bimetallic sulfide catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a conductive carrier with a specific precursor solution, and carrying out hydrothermal reaction to obtain a bimetallic precursor material; mixing with a thiourea solution, and carrying out hydrothermal reaction to obtain a vulcanized bimetallic precursor material; and then dipping in a mixed solution of an iridium salt alcoholic solution and a sodium hydroxide solution, and then taking out and drying to obtain the iridium-doped bimetallic sulfide catalyst. The efficient and stable iridium-doped bimetallic sulfide catalyst is synthesized through a simple hydrothermal method and an impregnation method, the iridium-doped bimetallic sulfide catalyst is used in an electro-catalysis oxygen evolution reaction, the catalytic activity of the catalyst can be obviously improved, and the catalyst has good stability. Moreover, the catalyst is simple in preparation process and rich in active sites, provides a new thought for realizing efficient electro-catalysis oxygen evolution reaction, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electrochemistry, and in particular to an iridium-doped bimetallic sulfide catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Since the first industrial revolution, the use of fossil fuels by humans has gradually increased. Fossil fuels include coal, petroleum, and natural gas. However, the extensive use of fossil fuels has brought many problems. First, fossil energy is a primary energy source and non-renewable. Uncontrolled use will eventually lead to energy depletion. Second, the extensive use of fossil energy will also cause irreversible damage to the environment. Therefore, researching and developing a new generation of clean energy, such as solar energy, wind energy, nuclear energy, hydrogen energy, etc., not only helps to meet the energy needs of humans but also can protect the environment to the greatest extent.

[0003] As a clean energy source, hydrogen is regarded as an excellent substitute for fossil fuels. However, free hydrogen molecules do not exist naturally, so hydrogen fuel needs to be prepared by different methods. Currently, there are mainly three methods for producing hydrogen industrially: one is the reforming of fossil fuels to produce hydrogen. The second is the production of hydrogen from industrial by-products, such as using solid palm oil waste and liquid palm oil to produce hydrogen; using an iron-based material as an oxygen carrier and methane as a fuel to produce hydrogen while producing iron oxide; using a process combining dark fermentation and microbial electrolysis to produce hydrogen from agricultural and industrial wastewater and by-products, etc. The third is the most common and important method, electrocatalytic water splitting to produce hydrogen, which consists of a hydrogen evolution reaction at the cathode and an electrocatalytic oxygen evolution reaction at the anode. The electrolysis of water reaction is essentially the reverse reaction of hydrogen combustion. In theory, it can achieve the complete closure and recycling of hydrogen, and the product is pollution-free, so it has received wide attention. The electrocatalytic oxygen evolution reaction (Oxygen Evolution Reaction, OER) occurs at the anode and requires a higher overpotential than the hydrogen evolution reaction (Hydrogen Evolution Reaction, HER) occurring at the cathode. Therefore, driving a reaction that requires a higher overpotential will accelerate the loss of electrode components. Therefore, designing a catalyst with high reaction activity to catalyze the electrolysis of water reaction is of great significance for reducing the reaction overpotential and improving the water decomposition efficiency.

[0004] So far, many noble metal-based catalysts have shown excellent performance in electrocatalytic oxygen evolution reaction in strong alkaline electrolytes, but the content of noble metal materials is small and the price is expensive, so it is difficult to be widely applied in industrial production. Therefore, there is an urgent need to develop non-noble metal catalyst materials and improve their application in electrocatalytic oxygen evolution reaction by optimizing the geometric and electronic structures of non-noble metal catalysts. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an iridium-doped bimetallic sulfide catalyst, a preparation method thereof and an application. The iridium-doped bimetallic sulfide catalyst prepared by the present invention has excellent reaction activity and stability in the electrocatalytic oxygen evolution reaction.

[0006] The present invention provides a preparation method of an iridium-doped bimetallic sulfide catalyst, comprising the following steps:

[0007] S1) Mix a conductive support with a precursor solution, and perform a hydrothermal reaction to obtain a bimetallic precursor material;

[0008] The precursor solution comprises a metal M salt, urea, ammonium fluoride and water; the metal M salt is selected from at least one of an iron salt, a cobalt salt, a manganese salt and a copper salt;

[0009] S2) Mix the bimetallic precursor material with a thiourea solution, and perform a hydrothermal reaction to obtain a sulfided bimetallic precursor material;

[0010] S3) Immerse the sulfided bimetallic precursor material in a mixed solution of an iridium salt alcohol solution and a sodium hydroxide solution, and then take it out and dry it to obtain an iridium-doped bimetallic sulfide catalyst; the iridium salt alcohol solution comprises an iridium salt and an alcohol solvent.

[0011] Preferably, in step S1), the metal M salt is selected from a chloride salt of metal M and / or a nitrate salt of metal M;

[0012] The molar ratio of the metal M salt, urea and ammonium fluoride is 6-12:5-10:1-5.

[0013] Preferably, in step S1), the metal M salt is selected from cobalt nitrate and copper nitrate; the molar ratio is 1.5-2.5:0.5-1.5;

[0014] The conductive support is carbon cloth or nickel foam.

[0015] Preferably, in step S1), the temperature of the hydrothermal reaction is 90-120 °C, and the time is 3-6 h.

[0016] Preferably, in step S2), the concentration of the thiourea solution is 0.02-0.03 g / mL.

[0017] Preferably, in step S2), the temperature of the hydrothermal reaction is 120-180 °C, and the time is 3-6 h.

[0018] Preferably, in step S3), the iridium salt alcohol solution comprises an iridium salt, an alcohol solvent and water;

[0019] In the iridium salt alcohol solution, the concentration of the iridium salt is 0.1-0.3 mg / mL;

[0020] The concentration of the sodium hydroxide solution is 0.2 to 0.3 mmol / L;

[0021] The impregnation time is 18 to 24 h.

[0022] The present invention also provides an iridium-doped bimetallic sulfide catalyst, which includes a conductive carrier and an iridium-doped bimetallic sulfide supported on the conductive carrier; the iridium-doped bimetallic sulfide is in a nanoneedle-like structure; the nanoneedle-like structure vertically grows on the conductive carrier to form a nanoflower-like structure.

[0023] The present invention also provides an application of the above-mentioned iridium-doped bimetallic sulfide catalyst in an electrocatalytic oxygen evolution reaction.

[0024] Preferably, the iridium-doped bimetallic sulfide catalyst is an anode catalyst;

[0025] The electrolyte solution for the electrocatalytic oxygen evolution reaction is an aqueous solution of alkali metal hydroxide; the pH value of the electrolyte solution is 10 to 14.

[0026] The present invention provides a preparation method of an iridium-doped bimetallic sulfide catalyst, which includes the following steps: S1) Mixing a conductive carrier with a precursor solution and performing a hydrothermal reaction to obtain a bimetallic precursor material; the precursor solution includes a metal M salt, urea, ammonium fluoride and water; the metal M salt is selected from at least one of an iron salt, a cobalt salt, a manganese salt and a copper salt; S2) Mixing the bimetallic precursor material with a thiourea solution and performing a hydrothermal reaction to obtain a sulfided bimetallic precursor material; S3) Impregnating the sulfided bimetallic precursor material in a mixed solution of an iridium salt alcohol solution and a sodium hydroxide solution, and then taking it out and drying to obtain an iridium-doped bimetallic sulfide catalyst; the iridium salt alcohol solution includes an iridium salt and an alcohol solvent. Compared with the prior art, the present invention synthesizes an efficient and stable iridium-doped bimetallic sulfide catalyst through simple hydrothermal and impregnation methods. When it is used in an electrocatalytic oxygen evolution reaction, the catalyst has a nanoflower-like structure, and the rough surface provides a high specific surface area, which is beneficial to charge transfer, can significantly improve the catalytic activity, and the catalyst has good stability. Moreover, the catalyst preparation process is simple and the active sites are abundant, providing a new idea for realizing an efficient electrocatalytic oxygen evolution reaction and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the XRD spectrum of the iridium-doped bimetallic sulfide catalyst and the sulfided bimetallic precursor material of Example 1 of the present invention;

[0028] Figure 2 is the scanning electron microscope image of the bimetallic precursor material of Example 1 of the present invention;

[0029] Figure 3 Scanning electron microscope image of the sulfided bimetallic precursor material of Example 1 of the present invention;

[0030] Figure 4 Scanning electron microscope image of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention;

[0031] Figure 5 XPS energy spectrum of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention;

[0032] Figure 6 Polarization curves of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention and the control material of Comparative Example 1 at a scanning rate of 5 mV / s;

[0033] Figure 7 Stability test diagram of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention. Detailed implementation manners

[0034] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0035] The present invention provides a preparation method of an iridium-doped bimetallic sulfide catalyst, including the following steps:

[0036] S1) Mix a conductive carrier with a precursor solution and perform a hydrothermal reaction to obtain a bimetallic precursor material;

[0037] The precursor solution includes a metal M salt, urea, ammonium fluoride, and water; the metal M salt is selected from at least one of an iron salt, a cobalt salt, a manganese salt, and a copper salt;

[0038] S2) Mix the bimetallic precursor material with a thiourea solution and perform a hydrothermal reaction to obtain a sulfided bimetallic precursor material;

[0039] S3) Immerse the sulfided bimetallic precursor material in a mixed solution of an iridium salt alcohol solution and a sodium hydroxide solution, and then take it out and dry it to obtain an iridium-doped bimetallic sulfide catalyst; the iridium salt alcohol solution includes an iridium salt and an alcohol solvent.

[0040] Regarding step S1):

[0041] Mix a conductive carrier with a precursor solution and perform a hydrothermal reaction to obtain a bimetallic precursor material;

[0042] The precursor solution includes a metal M salt, urea, ammonium fluoride, and water; the metal M salt is selected from at least one of iron salts, cobalt salts, manganese salts, and copper salts.

[0043] The precursor solution is obtained by mixing and dissolving a metal M salt, urea, ammonium fluoride, and water.

[0044] The water is deionized water.

[0045] In some embodiments of the present invention, the metal M is selected from at least one of iron, cobalt, manganese, and copper. The metal M salt is selected from chloride salts and / or nitrate salts of metal M. The cobalt salt is selected from cobalt chloride and / or cobalt nitrate. Specifically, the metal M salt is selected from cobalt nitrate and copper nitrate; the molar ratio is 1.5 - 2.5:0.5 - 1.5, such as 2:1. The molar ratio of the metal M salt, urea, and ammonium fluoride is 6 - 12:5 - 10:1 - 5, such as 8 - 10:7 - 10:2 - 5, such as 8 - 10:8 - 10:3 - 5, specifically 9:10:5.

[0046] The method of mixing and dissolving can be magnetic stirring. The time for mixing and dissolving is 30 - 60 min.

[0047] In some embodiments of the present invention, in the precursor solution, the concentration of the metal M salt is 0.06 - 0.4 mol / L, preferably 0.08 - 0.32 mol / L, more preferably 0.1 - 0.28 mol / L, most preferably 0.12 - 0.26 mol / L, specifically 0.18 mol / L.

[0048] In the present invention, a conductive carrier is mixed with the precursor solution, and a hydrothermal reaction is carried out to obtain a bimetallic precursor material.

[0049] In some embodiments of the present invention, the conductive carrier is carbon cloth or nickel foam. The unit weight of the carbon cloth is preferably 110 - 180 g / cm 2 , such as 130 g / cm 2 ; the thickness of the carbon cloth is preferably 0.1 - 0.5 mm, more preferably 0.3 - 0.4 mm, still more preferably 0.34 - 0.38 mm, such as 0.36 mm. The size of the carbon cloth is 2 cm × 4 cm.

[0050] The present invention does not have any special restrictions on the dosage ratio of the conductive carrier to the precursor solution, as long as the precursor solution can completely immerse the conductive carrier.

[0051] In some embodiments of the present invention, before mixing the conductive carrier with the precursor solution, it further includes: pretreating the conductive carrier. Specifically:

[0052] The conductive carrier is ultrasonically washed successively in acetone, absolute ethanol, water and nitric acid aqueous solution, and then washed with water and dried.

[0053] The conductive carrier is ultrasonically washed successively in acetone, absolute ethanol, water and nitric acid aqueous solution to remove impurities on the surface of the conductive carrier.

[0054] The time of each ultrasonic washing is independently 10 - 60 min, such as 30 min.

[0055] The water is deionized water.

[0056] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 90 - 120 °C, preferably 100 - 120 °C, more preferably 110 - 120 °C, and most preferably 120 °C; the time of the hydrothermal reaction is 3 - 6 h, preferably 4 - 6 h, more preferably 5 - 6 h, and most preferably 6 h.

[0057] After the hydrothermal reaction, it further includes: cooling to room temperature, washing and drying to obtain the bimetallic precursor material. Cooling to room temperature can be natural cooling to room temperature. The washing is preferably carried out with distilled water and ethanol; the drying is preferably vacuum drying; the temperature of the vacuum drying is preferably 50 - 80 °C, more preferably 50 - 60 °C, such as 60 °C; the time of the vacuum drying is preferably 10 - 24 h, such as 12 h.

[0058] Regarding step S2):

[0059] Mix the bimetallic precursor material with the thiourea solution and carry out a hydrothermal reaction to obtain the sulfided bimetallic precursor material.

[0060] In some embodiments of the present invention, the concentration of the thiourea solution is 0.02 - 0.03 g / mL, preferably 0.02 - 0.25 g / mL, and more preferably 0.02 g / mL.

[0061] The present invention has no special limitation on the dosage ratio of the bimetallic precursor material to the thiourea solution, and the thiourea solution can completely immerse the bimetallic precursor material.

[0062] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 120 - 180 °C, preferably 140 - 180 °C, more preferably 160 - 180 °C, and most preferably 180 °C; the time of the hydrothermal reaction is 3 - 6 h, preferably 4 - 6 h, more preferably 5 - 6 h, and most preferably 6 h.

[0063] After the hydrothermal reaction, the following steps are further included: cooling to room temperature, washing and drying to obtain a sulfided bimetallic precursor material. Cooling to room temperature can be natural cooling to room temperature. The washing is preferably carried out using distilled water and ethanol; the drying is preferably vacuum drying; the temperature of the vacuum drying is preferably 50-80°C, more preferably 50-60°C, such as 60°C; the time of the vacuum drying is preferably 10-24h, such as 12h.

[0064] Regarding step S3):

[0065] The sulfided bimetallic precursor material is impregnated in a mixed solution of an iridium salt alcohol solution and a sodium hydroxide solution, and then taken out and dried to obtain an iridium-doped bimetallic sulfide catalyst; the iridium salt alcohol solution includes an iridium salt and an alcohol solvent.

[0066] Specifically, the iridium salt alcohol solution includes an iridium salt, an alcohol solvent and water; the iridium salt can be any iridium salt well-known to those skilled in the art without special limitations, and in the present invention, it is preferably iridium chloride and / or iridium nitrate; the alcohol solvent is preferably methanol and / or ethanol, more preferably ethanol. The water is deionized water. The volume ratio of ethanol to water is 3:2. In the iridium salt alcohol solution, the concentration of the iridium salt is preferably 0.1-0.3mg / mL, more preferably 0.15-0.3mg / mL, still more preferably 0.2-0.3mg / mL, and most preferably 0.3g / mL. The iridium salt alcohol solution is preferably obtained by mixing an iridium salt and an alcohol solvent and ultrasonic dispersion; the time of the ultrasonic dispersion is preferably 30-60min, such as 45min.

[0067] In some embodiments of the present invention, the concentration of the sodium hydroxide solution is 0.2-0.3mmol / L; such as 0.25mmol / L.

[0068] In some embodiments of the present invention, the mass ratio of the iridium salt alcohol solution to the sodium hydroxide solution is 0.01-0.02:0.35-0.45, such as 0.015:0.4. The present invention has no special limitations on the dosage ratio of the sulfided bimetallic precursor material to the mixed solution, and the mixed solution can completely immerse the sulfided bimetallic precursor material.

[0069] In some embodiments of the present invention, the time of the impregnation is 18-24h, such as 24h.

[0070] The drying is preferably vacuum drying; the temperature of the vacuum drying is preferably 50-80°C, more preferably 50-60°C; the time of the vacuum drying is preferably 10-24h.

[0071] The present invention synthesizes an efficient and stable iridium-doped bimetallic sulfide catalyst through a simple hydrothermal and impregnation method and uses it for electrocatalytic oxygen evolution reaction. The catalyst has a nanoflower-like structure, and its rough surface provides a high specific surface area, which is conducive to charge transfer, can significantly improve the catalytic activity, and the catalyst has good stability. Moreover, the preparation process of the catalyst is simple and it has rich active sites, providing a new idea for realizing efficient electrocatalytic oxygen evolution reaction and having broad application prospects.

[0072] The present invention also provides an iridium-doped bimetallic sulfide catalyst prepared by the preparation method described above, including a conductive carrier and an iridium-doped bimetallic sulfide supported on the conductive carrier; the iridium-doped bimetallic sulfide has a nanoneedle-like structure; the nanoneedle-like structure grows vertically on the conductive carrier to form a nanoflower-like structure.

[0073] Specifically, the flower-like structure grows vertically on the conductive carrier to form a three-dimensional network-like nanoflower-like structure.

[0074] The present invention also provides an application of the iridium-doped bimetallic sulfide catalyst described above in electrocatalytic oxygen evolution reaction. Specifically, it provides an application of the iridium-doped bimetallic sulfide catalyst described above as an anode catalyst; that is, the application of the iridium-doped bimetallic sulfide catalyst as an anode catalyst in electrocatalytic oxygen evolution reaction.

[0075] The iridium-doped bimetallic sulfide catalyst is preferably an anode catalyst.

[0076] The electrocatalytic oxygen evolution reaction preferably adopts a three-electrode system; in the three-electrode system, the counter electrode is preferably a platinum electrode and the reference electrode is Ag / AgCl.

[0077] The electrocatalytic oxygen evolution reaction preferably uses a three-electrode electrolytic cell.

[0078] The electrolyte solution for the electrocatalytic oxygen evolution reaction is preferably an aqueous solution of alkali metal hydroxide, more preferably an aqueous solution of potassium hydroxide or sodium hydroxide; in some embodiments provided by the present invention, the concentration of the aqueous solution of alkali metal hydroxide is specifically 1 mol / L.

[0079] In order to further illustrate the present invention, the following examples are used to describe in detail the iridium-doped bimetallic sulfide catalyst, its preparation method and application provided by the present invention, but it should not be understood as a limitation to the protection scope of the present invention.

[0080] The reagents used in the following examples are all commercially available; the model of the carbon cloth used in the examples is HCP331N.

[0081] Example 1

[0082] 1.1 The carbon cloth with a size of 2 cm × 4 cm and a thickness of 0.36 mm (unit weight: 130 g / cm 2 ) was successively ultrasonically washed in acetone, absolute ethanol, deionized water, and nitric acid aqueous solution for 30 min each to remove impurities on the surface of the carbon cloth, and then washed with deionized water and dried to obtain the pretreated carbon cloth.

[0083] 6 mmol of cobalt nitrate, 3 mmol of copper nitrate, 10 mmol of urea, 5 mol of ammonium fluoride were mixed with 50 mL of deionized water and dissolved by magnetic stirring for 45 min to obtain a precursor solution.

[0084] 1.2 The pretreated carbon cloth was placed in the precursor solution and transferred to a hydrothermal autoclave with a Teflon liner. After hydrothermal reaction at 120 °C for 6 h, the carbon cloth substrate was taken out from the hydrothermal autoclave, washed with distilled water and ethanol, and vacuum dried at 60 °C for 12 h to obtain a bimetallic precursor material (CuCo 2 @CC).

[0085] 1.3 The bimetallic precursor material was placed in a mixed solution containing 1 g of thiourea and 50 mL of water and transferred to a hydrothermal autoclave with a Teflon liner. After hydrothermal reaction at 180 °C for 6 h, the carbon cloth substrate was taken out from the hydrothermal autoclave, washed with distilled water and ethanol, and vacuum dried at 60 °C for 12 h to obtain a sulfided bimetallic precursor material (CuCo 2 S a @CC).

[0086] 1.4 The sulfided bimetallic precursor material was immersed in a mixed solution of an ethanol solution of IrCl 3 ·3H 2 O (obtained by mixing 15 mg of IrCl 3 ·3H 2 O, 30 mL of ethanol, and 20 mL of water and ultrasonic dispersion for 45 min) and 0.25 mmol / L sodium hydroxide solution for 24 h; the mass ratio of the ethanol solution of IrCl 3 ·3H 2 O to the sodium hydroxide solution is 0.015:0.4; then it was vacuum dried at 60 °C for 12 h to obtain an iridium-doped bimetallic sulfide catalyst (Ir-CuCo 2 S a @CC).

[0087] Comparative Example 1

[0088] Preparation of Control Material 1 and Control Material 2:

[0089] The difference from Example 1 is as follows:

[0090] Replacing copper nitrate in Step 1.1 with manganese chloride or iron nitrate can obtain MnCo 2 @CC and FeCo 2 @CC bimetallic precursor materials;

[0091] Steps 1.3 and 1.4 are not included.

[0092] Preparation of Control Material 3:

[0093] The difference from Example 1 is:

[0094] Annealing the bimetallic precursor material obtained in Step 1.2 in an air atmosphere at 350 °C for 2 h to obtain a CuCo 2 O 4 @CC sample;

[0095] Steps 1.3 and 1.4 are not included.

[0096] Example 2

[0097] 1.1 A carbon cloth with a size of 2 cm × 4 cm and a thickness of 0.36 mm (unit weight of 130 g / cm 2 ) was successively ultrasonically washed in acetone, absolute ethanol, deionized water, and nitric acid aqueous solution for 30 min each to remove impurities on the surface of the carbon cloth, and then washed with deionized water and dried to obtain the pretreated carbon cloth.

[0098] Mix 6 mmol of cobalt nitrate, 3 mmol of copper nitrate, 10 mmol of urea, 5 mmol of ammonium fluoride with 50 mL of deionized water, and dissolve by magnetic stirring for 45 min to obtain a precursor solution.

[0099] 1.2 Place the pretreated carbon cloth in the precursor solution, transfer it to a hydrothermal autoclave with a Teflon lining, carry out hydrothermal reaction at 150 °C for 6 h, then take out the carbon cloth substrate from the hydrothermal autoclave, wash it with distilled water and ethanol, and vacuum dry it at 60 °C for 12 h to obtain a bimetallic precursor material.

[0100] 1.3 Place the bimetallic precursor material in a mixed solution containing 1 g of thiourea and 50 mL of water, transfer it to a hydrothermal autoclave with a Teflon lining, carry out hydrothermal reaction at 160 °C for 6 h, then take out the carbon cloth substrate from the hydrothermal autoclave, wash it with distilled water and ethanol, and vacuum dry it at 60 °C for 12 h to obtain a sulfided bimetallic precursor material.

[0101] 1.4 Place the sulfided bimetallic precursor material in an ethanol solution of IrCl 3 ·3H 2 O (prepared from 15 mg of IrCl 3 ·3H 2O, 30 mL of ethanol and 20 mL of water were mixed and ultrasonically dispersed for 45 min to obtain) and impregnated in a mixed solution of 0.25 mmol / L sodium hydroxide solution for 12 h; the mass ratio of the ethanol solution of IrCl 3 ·3H 2 O to the sodium hydroxide solution was 0.015:0.4; then it was vacuum dried at 60 °C for 12 h to obtain an iridium-doped bimetallic sulfide catalyst.

[0102] Comparative Example 2

[0103] The difference from Example 2 is that:

[0104] Step 1.4 was:

[0105] The bimetallic precursor material obtained in Step 1.2 of Example 2 was annealed in an air atmosphere at 300 °C for 2 h to obtain CuCo 2 O 4 @CC sample;

[0106] It does not contain Step 1.3 and Step 1.4.

[0107] Comparative Example 3

[0108] The difference from Example 2 is that:

[0109] Step 1.4 was:

[0110] The sulfided bimetallic precursor material was placed in a solution of Ni(NO 3 ) 2 ·6H 2 O in ethanol (obtained by mixing 15 mg of Ni(NO 3 ) 2 ·6H 2 O, 30 mL of ethanol and 20 mL of water and ultrasonically dispersing for 45 min) and impregnated in a mixed solution of 0.25 mmol / L sodium hydroxide solution for 12 h; the mass ratio of the ethanol solution of Ni(NO 3 ) 2 ·6H 2 O to the sodium hydroxide solution was 0.015:0.4; then it was vacuum dried at 60 °C for 12 h to obtain a nickel-doped bimetallic sulfide catalyst.

[0111] Comparative Example 4

[0112] The difference from Example 2 is that:

[0113] Step 1.4 was:

[0114] The sulfided bimetallic precursor material was placed in Na 2 MoO 4 ·2H 2An ethanol solution of O (prepared by mixing 15 mg of Na 2 MoO 4 ·2H 2 O, 30 mL of ethanol and 20 mL of water, and ultrasonic dispersing for 45 min) was impregnated in a mixed solution of 0.25 mmol / L sodium hydroxide solution for 12 h. The mass ratio of the ethanol solution of Na 2 MoO 4 ·2H 2 O and the sodium hydroxide solution was 0.015:0.4; then it was vacuum dried at 60 °C for 12 h to obtain a molybdenum-doped bimetallic sulfide catalyst.

[0115] Crystal structure analysis of the sample:

[0116] The obtained iridium-doped bimetallic sulfide catalyst in Example 1 and the control material obtained in Comparative Example 1 were scanned for XRD patterns using a Rigaku Ultima IV X-ray powder diffractometer in Japan. The specific operation process and equipment parameters are as follows: The prepared iridium-doped bimetallic sulfide catalyst (or control material) was cut into a small piece, adhered to the test disk with conductive adhesive and placed in the XRD sample stage for XRD pattern scanning. The scanning parameters are as follows, the scanning range was set to 10° to 80°, and the scanning speed was 2° / min. The results are as Figure 1 shown. Figure 1 This is the XRD pattern of the iridium-doped bimetallic sulfide catalyst and the sulfided bimetallic precursor material (i.e., the bimetallic sulfide precursor material) in Example 1 of the present invention.

[0117] From Figure 1 it can be seen that the main peak in the XRD pattern points to CuCo 2 S 4 (PDF#42-1450), indicating that the bimetallic sulfide precursor has a spinel sulfide structure. At the same time, after impregnation in the iridium salt alcohol solution, the XRD pattern of the iridium-doped bimetallic sulfide catalyst is very similar to that of the bimetallic sulfide precursor, and its characteristic peaks are slightly shifted to the left compared with CuCo 2 S 4 . This shows that Ir and S have been successfully introduced into the precursor, and this transition metal heterostructure nanosheet supported on a three-dimensional carbon cloth substrate has been obtained.

[0118] Characterization of the sample morphology:

[0119] A Hitachi Regulus 8100 scanning electron microscope was used. The preparation method of the test sample is as follows:

[0120] The bimetallic precursor material obtained in Example 1 was cut into squares with a size of 0.5 mm × 0.5 mm, adhered to a silicon wafer with conductive glue, and the silicon wafer was placed on the copper plate of the mounting table. Subsequently, morphology observation was carried out to obtain its scanning electron microscope image, as Figure 2 shown. Figure 2 This is the scanning electron microscope image of the bimetallic precursor material of Example 1 of the present invention.

[0121] The sulfided bimetallic precursor material obtained in Example 1 was cut into squares with a size of 0.5 mm × 0.5 mm, adhered to a silicon wafer with conductive glue, and the silicon wafer was placed on the copper plate of the mounting table. Subsequently, morphology observation was carried out to obtain its scanning electron microscope image, as Figure 3 shown. Figure 3 This is the scanning electron microscope image of the sulfided bimetallic precursor material of Example 1 of the present invention.

[0122] The iridium-doped bimetallic sulfide catalyst obtained in Example 1 was cut into squares with a size of 0.5 mm × 0.5 mm, adhered to a silicon wafer with conductive glue, and the silicon wafer was placed on the copper plate of the mounting table. Subsequently, morphology observation was carried out to obtain its scanning electron microscope image, as Figure 4 shown. Figure 4 This is the scanning electron microscope image of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention.

[0123] It can be seen from Figures 2 to 4 that the bimetallic sulfide catalyst shows a uniform nanoneedle structure. The surface of the nanoneedle structure is rough and particles are loaded on the overall needle-like structure, with almost no obvious aggregation. The nanoneedles grow vertically to construct a three-dimensional nanoflower-like structure. The rough surface provides a high specific surface area, which is beneficial to charge transfer and can significantly improve the catalytic activity. The iridium-doped bimetallic sulfide catalyst was prepared by impregnation in a solution containing iridium. Due to the small impregnation amount of iridium, the morphology basically did not change, and the particulate morphology possessed by the bimetallic sulfide catalyst was retained.

[0124] X-ray photoelectron spectroscopy (XPS) of the sample:

[0125] The XPS spectrum of the sample was measured using a Thermo Fisher Scientific K-Alpha in the United States. The base vacuum of the instrument was 3×10 -9 mbar and the power was 300 W. When processing the data, the C1s peak of contaminated carbon was used to perform energy correction on the XPS. Secondly, by comparing with the standard spectrum and using the XPSPEAK software to perform peak fitting on the full spectrum of the XPS and the high-resolution spectra of the main metal elements, the valence state and type of the elements were preliminarily judged, and the XPS energy spectrum of the iridium-doped bimetallic sulfide catalyst was obtained, as Figure 5 shown. Figure 5XPS energy spectrum of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention.

[0126] It can be seen from Figure 5 that the surface of the iridium-doped bimetallic sulfide sample is mainly composed of Cu, Co, S, and Ir elements. At the same time, the presence of sulfide can increase the conductivity. After doping with Ir, it is beneficial to accelerate electron transfer and promote proton adsorption, thereby improving the catalytic performance.

[0127] Polarization curve of the electrode material:

[0128] The iridium-doped bimetallic sulfide catalyst obtained in Example 1 (or the control material of Comparative Example 1) was used as the working electrode, and then the Ag / AgCl electrode and the Pt sheet were used as the reference electrode and the counter electrode respectively, and 1 mol / L aqueous potassium hydroxide solution was used as the electrolyte. The test was carried out on a Shanghai Chenhua 760E electrochemical workstation at a scanning rate of 5 mV / s. The results are as Figure 6 shown. Figure 6 Polarization curves of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention and the control material of Comparative Example 1 at a scanning rate of 5 mV / s respectively.

[0129] It can be seen from Figure 6 that the CuCo 2 O 4 @CC sample of Comparative Example 1 requires 1.494 V (corresponding to 10 mA cm -2 ) and 1.595 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density, and the MnCo 2 @CC sample requires 1.503 V (corresponding to 10 mA cm -2 ) and 1.68 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density, and the FeCo 2 @CC sample requires 1.553 V (corresponding to 10 mA cm -2 ) and 1.645 V (corresponding to 100 mA cm -2 ).

[0130] The sulfided bimetallic precursor material of Example 1 requires low potentials of 1.445 V (corresponding to 10 mA cm -2 ) and 1.578 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density; the iridium-doped bimetallic sulfide requires 1.434 V (corresponding to 10 mA cm -2 ) and 1.567 V (corresponding to 100 mA cm -2) The low potential indicates that the synergistic effect between sulfur and iridium is more advantageous in enhancing the oxygen evolution reaction performance than single sulfur doping. Meanwhile, as the current density increases, the overpotential of the iridium-doped bimetallic sulfide catalyst decreases, indicating that the doping of sulfur and iridium promotes charge transfer and gradually optimizes the oxygen evolution reaction activity.

[0131] Using the iridium-doped bimetallic sulfide catalyst obtained in Example 2 (or the control material in Comparative Example 2) as the working electrode, then using an Ag / AgCl electrode and a Pt sheet as the reference electrode and the counter electrode respectively, and using 1 mol / L aqueous potassium hydroxide solution as the electrolyte. The test was carried out on a Shanghai Chenhua 760E electrochemical workstation at a scanning rate of 5 mV / s. The experimental results show that the sulfided bimetallic precursor material in Example 2 requires 1.495 V (corresponding to 10 mA cm -2 ) and 1.678 V (corresponding to 100 mA cm -2 ) at low potential; the iridium-doped bimetallic sulfide requires 1.503 V (corresponding to 10 mA cm -2 ) and 1.596 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density; the catalyst in Comparative Example 2 requires 1.521 V (corresponding to 10 mA cm -2 ) and 1.698 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density.

[0132] Using the nickel-doped bimetallic sulfide catalyst obtained in Comparative Example 3 as the working electrode, then using an Ag / AgCl electrode and a Pt sheet as the reference electrode and the counter electrode respectively, and using 1 mol / L aqueous potassium hydroxide solution as the electrolyte. The test was carried out on a Shanghai Chenhua 760E electrochemical workstation at a scanning rate of 5 mV / s. The experimental results show that the nickel-doped bimetallic sulfide in Comparative Example 3 requires 1.5 V (corresponding to 10 mA cm -2 ) and 1.574 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density.

[0133] Using the molybdenum-doped bimetallic sulfide catalyst obtained in Comparative Example 4 as the working electrode, then using an Ag / AgCl electrode and a Pt sheet as the reference electrode and the counter electrode respectively, and using 1 mol / L aqueous potassium hydroxide solution as the electrolyte. The test was carried out on a Shanghai Chenhua 760E electrochemical workstation at a scanning rate of 5 mV / s. The experimental results show that the molybdenum-doped bimetallic sulfide in Comparative Example 4 requires 1.597 V (corresponding to 10 mA cm -2 ) and 1.714 V (corresponding to 100 mA cm -2 ) to reach the corresponding current density.

[0134] Stability of the electrode material:

[0135] The stability of the electrocatalytic oxygen evolution reaction was evaluated by repeated i-t tests. The constant current test was terminated after 22 h, and the long-term stability of the iridium-doped bimetallic sulfide sample of Example 1 was verified in 1 mol / L aqueous potassium hydroxide solution. The results are as Figure 7 shown. Figure 7 This is the stability test chart of the iridium-doped bimetallic sulfide catalyst of Example 1 of the present invention.

[0136] It can be seen from Figure 7 that after 22 h, the potential of this electrode material increased by 123 mV, indicating good catalytic stability and excellent OER oxidation performance.

[0137] According to the above method, the stability test of the iridium-doped bimetallic sulfide catalyst of Example 2 was carried out. The experimental results showed that after 22 h, the potential of this electrode material increased by 92 mV.

[0138] According to the above method, the stability test of the nickel-doped bimetallic sulfide catalyst of Comparative Example 3 was carried out. The experimental results showed that after 22 h, the electrode potential decreased by 20 mV.

[0139] According to the above method, the stability test of the molybdenum-doped bimetallic sulfide catalyst of Comparative Example 4 was carried out. The experimental results showed that after 22 h, the electrode potential decreased by 43 mV.

[0140] In summary, the present invention prepares an iridium-doped bimetallic sulfide catalyst in-situ grown on carbon cloth with carbon cloth as the substrate by a method of hydrothermal treatment followed by impregnation, which can be used as a highly active and stable OER electrocatalyst. This catalyst helps to significantly reduce the energy consumption of water electrolysis and improve the water decomposition efficiency. The present invention provides a new strategy for designing highly efficient and low-cost OER electrocatalysts to promote the development of green hydrogen production, and provides a new idea for realizing efficient electrocatalytic oxygen evolution reaction.

[0141] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an iridium-doped bimetallic sulfide catalyst, comprising the following steps: S1) mixing the conductive carrier with the precursor solution and performing a hydrothermal reaction to obtain a bimetallic precursor material; The precursor solution comprises a metal M salt, urea, ammonium fluoride and water; the metal M salt is selected from at least one of an iron salt, a cobalt salt, a manganese salt and a copper salt; S2) mixing the bimetallic precursor material with a thiourea solution and performing a hydrothermal reaction to obtain a sulfurized bimetallic precursor material; S3) immersing the sulfided bimetallic precursor material in a mixed solution of an iridium salt alcohol solution and a sodium hydroxide solution, and then taking it out and drying it to obtain an iridium-doped bimetallic sulfide catalyst; the iridium salt alcohol solution includes an iridium salt and an alcohol solvent.

2. The preparation method according to claim 1, characterized in that: In step S1), the metal M salt is selected from a chloride of metal M and / or a nitrate of metal M; The molar ratio of the metal M salt, urea and ammonium fluoride is 6-12:5-10:1-5.

3. The preparation method according to claim 1, characterized in that: In step S1), the metal M salt is selected from cobalt nitrate and copper nitrate; the molar ratio is 1.5-2.5:0.5-1.5; The conductive carrier is carbon cloth or nickel foam.

4. The preparation method according to claim 1, characterized in that: In step S1), the temperature of the hydrothermal reaction is 90-120° C. and the time is 3-6 hours.

5. The preparation method according to claim 1, characterized in that: In step S2), the concentration of the thiourea solution is 0.02-0.03 g / mL.

6. The preparation method according to claim 1, characterized in that: In step S2), the temperature of the hydrothermal reaction is 120-180° C. and the time is 3-6 hours.

7. The preparation method according to claim 1, characterized in that: In step S3), the iridium salt alcohol solution comprises iridium salt, alcohol solvent and water; In the iridium salt alcohol solution, the concentration of iridium salt is 0.1-0.3 mg / mL; The concentration of the sodium hydroxide solution is 0.2-0.3 mmol / L; The immersion time is 18 to 24 hours.

8. An iridium-doped bimetallic sulfide catalyst, characterized in that: It comprises a conductive carrier and iridium-doped bimetallic sulfide loaded on the conductive carrier; the iridium-doped bimetallic sulfide is a nano needle-like structure; the nano needle-like structure grows vertically on the conductive carrier to form a nano flower-like structure.

9. Use of the iridium-doped bimetallic sulfide catalyst according to claim 8 in an electrocatalytic oxygen evolution reaction.

10. The use according to claim 9, characterized in that: The iridium-doped bimetallic sulfide catalyst is an anode catalyst; The electrolyte solution for the electrocatalytic oxygen evolution reaction is an alkali metal hydroxide aqueous solution; the pH value of the electrolyte solution is 10-14.

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