Supported Ir / TaB2 catalyst as well as preparation method and application thereof

Abstract

The invention relates to a supported Ir / TaB2 catalyst and a preparation method and application thereof.The preparation method comprises the steps that tantalum diboride and urea are dissolved in deionized water, after ultrasonic treatment is conducted at the room temperature, iridium tetrachloride is added, ultrasonic treatment is conducted again, an obtained reaction mixture is subjected to a hydrothermal reaction, after the reaction is completed, a reaction product is cooled to the room temperature, and then vacuum drying is conducted; and calcining the dried reactant to obtain a black product, and carrying out centrifugal washing and room-temperature airing on the black product to obtain the supported Ir / TaB2 catalyst. The synthesis method has the advantages of simplicity, few operation steps, short time consumption, low cost, no need of expensive instruments and equipment, easily available raw materials, economy, environmental protection and easiness in large-scale production. The prepared Ir / TaB2 catalyst is used as an anode catalyst for PEM electro-catalysis water decomposition hydrogen production, the anode oxygen evolution overpotential can be remarkably reduced, the current is increased, and the Ir / TaB2 catalyst has high activity and good use stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of proton exchange membrane (PEM) electrocatalytic water decomposition to produce hydrogen, and relates to an anode catalyst for PEM electrocatalytic water decomposition to produce hydrogen and a preparation method thereof, in particular to a supported Ir / TaB2 catalyst and a preparation method and application thereof. Background Art

[0002] Using renewable energy such as wind, solar, and geothermal energy to electrolyze water is a green hydrogen production technology. Compared with traditional alkaline electrolyzers, proton exchange membrane electrolyzers have the advantages of fast response speed, high power density, high efficiency, and high gas purity, and are considered to be the next generation of hydrogen production technology. Water electrolysis mainly involves two half-reaction processes, the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The slower kinetics of the oxygen evolution reaction at the anode, the higher overpotential, and the strong acid and strong oxidizing environment make the research and development of OER catalysts an important direction for the large-scale promotion and application of PEM electrocatalytic water splitting hydrogen production technology.

[0003] So far, iridium, ruthenium-based noble metals and their derivatives are widely regarded as excellent anode catalysts for OER. Ruthenium oxide has excellent activity under acidic conditions, but it is more easily oxidized to cause the structural collapse of the catalyst, resulting in the dissolution of the catalyst and the reduction of catalytic activity. Iridium oxide can maintain good catalytic activity while having good stability, but its reserves are low, production capacity is limited and it is expensive, which increases the cost of PEM water electrolysis. Loading precious metals or other active phases on suitable carriers can improve the utilization, activity and stability of active components and reduce the production cost of catalysts, which is of great significance to the large-scale application of PEM water electrolysis.

[0004] Patent CN117626329A discloses a PEM water electrolysis supported Ir / MnO2 catalyst and its preparation method, which first utilizes high-valent Nb +5 MnO2 is doped to form a Nb-MnO2 carrier, and then Ir nanoparticles are uniformly loaded on Nb-MnO2 to form an Ir / Nb-MnO2 supported catalyst through a cation exchange method. This patent can reduce the use of precious metals, but the niobium pentachloride used does not conform to the concept of environmentally friendly chemistry, and the process is complicated and time-consuming.

[0005] Patent CN114657577B discloses a method for preparing a supported catalyst for PEM water electrolysis, comprising the following steps: first, spinning conductive polymer nanofibers of various sizes using an electrospinning machine, using the conductive polymer nanofibers as templates, immersing them in a chloroiridic acid solution, adding excess sodium borohydride to reduce the chloroiridic acid to iridium nanoparticles and load them on the surface of the nanofibers, and calcining the iridium / conductive polymer nanofibers to obtain a finished catalyst. However, the size of the carrier prepared by the electrospinning technology in this patent is much larger than that of the metal oxide carrier, which is not conducive to the uniform dispersion of the active substance and the improvement of the catalyst activity.

[0006] Patent CN118390091A discloses a method for preparing a high-activity supported iridium-based catalyst, the carrier of which is anatase TiO2: dissolving iridium salt in ethylene glycol to prepare solution A; dissolving alkaline substance in ethylene glycol to prepare solution B; adjusting the pH of solution A to alkaline with solution B to obtain precursor solution C; dissolving titanium salt in ethylene glycol solution, then adding water to prepare solution D, and then performing solvent thermal reaction to obtain titanium oxide carrier; uniformly dispersing titanium oxide carrier in ethylene glycol to prepare dispersion E; slowly dropping precursor solution C into dispersion E to prepare dispersion F with a certain iridium loading, then heating to a certain temperature, and keeping the temperature for a certain time, separating, washing, and drying after cooling to a certain temperature to obtain supported iridium-based catalyst. The supported iridium-based catalyst synthesis process is complicated and time-consuming.

[0007] In summary, the current synthesis process of supported iridium-based catalysts is complicated, not environmentally friendly, and time-consuming, and the synthesized catalysts have poor catalytic activity and stability. Therefore, there is an urgent need to provide a new supported iridium-based catalyst with both high activity and stability and a preparation method thereof. Summary of the invention

[0008] The purpose of the present invention is to provide a supported Ir / TaB2 catalyst and a preparation method and application thereof, aiming to solve the problems of the existing supported iridium-based catalyst synthesis method, such as complex operation, environmental pollution, long time consumption, low catalyst activity and stability.

[0009] The present invention is specifically achieved through the following technical scheme. A preparation method of a supported Ir / TaB2 catalyst proposed in the present invention comprises the following steps: dissolving tantalum diboride and urea in deionized water, ultrasonicating at room temperature for 30 to 60 min, then adding iridium tetrachloride thereto, ultrasonicating at room temperature for 30 to 60 min again, transferring the obtained reaction mixture to the lining of a high-pressure reactor for hydrothermal reaction, cooling the reaction product to room temperature after the reaction is completed, and then vacuum drying the reaction product; transferring the dried reaction product to a porcelain boat, placing the porcelain boat in a tubular furnace, and calcining it in an Ar / H2 atmosphere to obtain a black product, centrifuging and washing the black product, and air-drying it at room temperature to obtain a supported Ir / TaB2 catalyst.

[0010] In the preparation method of the aforementioned supported Ir / TaB2 catalyst, the molar ratio of tantalum diboride to iridium is 1:(1~2).

[0011] In the preparation method of the aforementioned supported Ir / TaB2 catalyst, the molar ratio of urea to iridium is (1~4):1.

[0012] In the aforementioned method for preparing the supported Ir / TaB2 catalyst, the temperature of the hydrothermal reaction is 90-120°C, and the time of the hydrothermal reaction is 3-5 h.

[0013] In the aforementioned method for preparing the supported Ir / TaB2 catalyst, the vacuum drying temperature is 70°C and the vacuum drying time is 10 to 12 h.

[0014] In the preparation method of the aforementioned supported Ir / TaB2 catalyst, the calcination temperature is 450°C and the calcination time is 4 to 6 hours.

[0015] In the preparation method of the aforementioned supported Ir / TaB2 catalyst, during washing, the black product is first centrifugally washed 2 to 3 times with anhydrous ethanol, and then centrifugally washed 6 to 10 times with deionized water.

[0016] The prepared supported Ir / TaB2 catalyst by the aforementioned method for preparing the supported Ir / TaB2 catalyst has a particle size of 3-4 nm and characteristic peaks of elemental iridium and tantalum diboride are present in its XRD spectrum.

[0017] The present invention also provides an application of the supported Ir / TaB2 catalyst obtained according to the above preparation method as an anode catalyst in PEM water electrolysis.

[0018] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technical progress and practicality, and has a wide range of utilization value, and has at least the following advantages: The present invention uses tantalum diboride as a carrier, iridium tetrachloride as an iridium source, and urea as a ligand. Through hydrothermal reaction and high-temperature calcination in an Ar / H2 atmosphere, iridium tetrachloride is reduced to iridium, and iridium is loaded on the tantalum diboride carrier as an active component to obtain a loaded Ir / TaB2 catalyst with a smaller size and uniform particle distribution. The loaded Ir / TaB2 catalyst has a uniform particle size of about 3 to 4 nm and a uniform size. The XRD spectrum contains characteristic peaks of elemental iridium and tantalum diboride, indicating that the elemental iridium has been uniformly loaded on the tantalum diboride carrier. Its LSV curve shows that at a current density of 10 mA cm -2 The supported Ir / TaB2 catalyst has a smaller overpotential than the commercial iridium black catalyst, indicating that the supported Ir / TaB2 catalyst prepared by the present invention has better acidic oxygen evolution reaction activity than the commercial iridium black catalyst. The catalyst stability test results show that after CV cycles of 30,000 cycles, the catalyst can be used at a current density of 10 mA cm -2 When the overpotential of the Ir / TaB2 catalyst increased by only 22 mV, while under the same conditions, the overpotential of the commercial iridium-based catalyst increased by 33~40 mV, indicating that the supported Ir / TaB2 catalyst prepared by the present invention has excellent cycle stability.

[0019] The synthesis method of the supported Ir / TaB2 catalyst provided by the present invention is simple, has few operation steps, short time consumption, low cost, no need for expensive instruments and equipment, easy raw materials, economic and environmental protection, and easy large-scale production. The prepared Ir / TaB2 catalyst is used as an anode catalyst for PEM electrocatalytic water decomposition to produce hydrogen, which can significantly reduce the anode oxygen evolution overpotential, increase the current, have excellent catalytic performance, and have both high activity and good stability in use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the XRD pattern of the supported Ir / TaB2 catalyst prepared in Example 1.

[0021] Figure 2 This is the TEM image of the supported Ir / TaB2 catalyst prepared in Example 1.

[0022] Figure 3 It is a comparison diagram of the LSV curves of the oxygen evolution reaction of the supported Ir / TaB2 catalyst prepared in Example 1 and the commercial iridium black catalyst in Comparative Example 1 under acidic conditions.

[0023] Figure 4 This is a stability test effect diagram of the supported Ir / TaB2 catalyst prepared in Example 1. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention is described in detail with specific examples below. In the following examples, if the specific conditions are not specified, they are all carried out according to the normal conditions or the conditions recommended by the manufacturer. The raw materials and reagents used are conventional products that can be purchased commercially without specifying the manufacturer. The iridium tetrachloride used in the following examples is purchased from Beijing Inokai Technology Co., Ltd., with the article number 207399-11-9 and a molecular weight of 334.03.

[0026] Example 1 First, 365 mg of tantalum diboride and 108 mg of urea were dissolved in 30 mL of deionized water, ultrasonicated at room temperature for 30 min, and then 601 mg of iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 min again. The obtained reaction mixture was transferred to the lining of the autoclave and hydrothermally reacted at 110 ° C for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then placed in a vacuum drying oven at 70 ° C for 10 h. The dried reaction product was transferred to a porcelain boat, which was placed in a tube furnace and heated at 5 ° C min under an Ar / H2 atmosphere. -1 The temperature was raised to 450℃ and calcined for 5 h to obtain a black product. The black product was first washed 3 times with anhydrous ethanol by centrifugation, then washed 8 times with deionized water by centrifugation, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

[0027] Example 2 First, 182.5 mg of tantalum diboride and 108 mg of urea were dissolved in 30 mL of deionized water, ultrasonicated at room temperature for 30 min, and then 601 mg of iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 min again. The obtained reaction mixture was transferred to the lining of the autoclave and hydrothermally reacted at 110 ° C for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then placed in a vacuum drying oven at 70 ° C for 10 h. The dried reaction product was transferred to a porcelain boat, which was placed in a tube furnace and heated at 5 ° C min under an Ar / H2 atmosphere. -1 The temperature was raised to 450℃ and calcined for 5 h to obtain a black product. The black product was first washed 3 times with anhydrous ethanol by centrifugation, then washed 7 times with deionized water by centrifugation, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

[0028] Example 3 First, 365 mg of tantalum diboride and 216 mg of urea were dissolved in 30 mL of deionized water, ultrasonicated at room temperature for 30 min, and then 601 mg of iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 min again. The obtained reaction mixture was transferred to the lining of the autoclave and hydrothermally reacted at 110 ° C for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then placed in a vacuum drying oven at 70 ° C for 10 h. The dried reaction product was transferred to a porcelain boat, which was placed in a tube furnace and heated at 5 ° C min under an Ar / H2 atmosphere. -1 The temperature was raised to 450℃ and calcined for 5 h to obtain a black product. The black product was first washed 3 times with anhydrous ethanol by centrifugation, then washed 8 times with deionized water by centrifugation, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

[0029] Example 4 First, 365 mg of tantalum diboride and 108 mg of urea were dissolved in 30 mL of deionized water, ultrasonicated at room temperature for 30 min, and then 601 mg of iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 min again. The obtained reaction mixture was transferred to the lining of the autoclave, and hydrothermally reacted at 90 ° C for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then placed in a vacuum drying oven at 70 ° C for 10 h. The dried reaction product was transferred to a porcelain boat, which was placed in a tube furnace and heated at 5 ° C min under an Ar / H2 atmosphere. -1 The temperature was raised to 450℃ and calcined for 5 h to obtain a black product. The black product was first washed 3 times with anhydrous ethanol by centrifugation, then washed 7 times with deionized water by centrifugation, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

[0030] Example 5 First, 365 mg of tantalum diboride and 108 mg of urea were dissolved in 30 mL of deionized water, ultrasonicated at room temperature for 30 min, and then 601 mg of iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 min again. The obtained reaction mixture was transferred to the lining of the autoclave and hydrothermally reacted at 110 ° C for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then placed in a vacuum drying oven at 70 ° C for 10 h. The dried reaction product was transferred to a porcelain boat, which was placed in a tube furnace and heated at 5 ° C min under an Ar / H2 atmosphere. -1 The temperature was raised to 450℃ and calcined for 8 h to obtain a black product. The black product was first washed 3 times with anhydrous ethanol by centrifugation, then washed 8 times with deionized water by centrifugation, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

[0031] Comparative Example 1 A commercial iridium black catalyst was used, purchased from Alfa, product number: 010746.

[0032] Comparative Example 2 A commercial iridium oxide catalyst was used, purchased from Sigma Aldrich, product number 206237.

[0033] The supported Ir / TaB2 catalyst prepared in Example 1 was characterized. The XRD test instrument used was a Japan-Rigaku-SmartLab 9 kW, Cu-Kα diffraction (1.54184Å); the TEM+Mapping test instrument used a JEOL JEM-ARM200F Cs-corrected S / TEM for HAADF-STEM tomography. Its XRD spectrum is shown in Figure 1 As shown, Figure 1 The XRD spectrum of the composite contains characteristic peaks of iridium and tantalum diboride, indicating that iridium has been uniformly loaded on the tantalum diboride carrier.

[0034] Figure 2 This is a TEM image of the supported Ir / TaB2 catalyst prepared in Example 1. The particle size of the supported Ir / TaB2 catalyst is about 3-4 nm, and the particle distribution is uniform.

[0035] The prepared supported Ir / TaB2 catalyst is used as the anode catalyst for PEM water electrolysis. The specific application method is as follows: 10 mg of the supported Ir / TaB2 catalyst prepared in Examples 1 to 5, 10 mg of the commercial iridium black catalyst in Comparative Example 1, and 10 mg of the commercial iridium oxide catalyst in Comparative Example 2 are weighed respectively, and 109 μL of 5% Nafion solution, 545 μL of ultrapure water, and 1345 μL of isopropanol are added to each catalyst to prepare a catalyst mixture, and the catalyst mixture is ultrasonicated for at least 2 h to mix it evenly to obtain a catalyst dispersion. 15 μL of the catalyst dispersion is taken with a pipette, and evenly dripped on the surface of the glassy carbon electrode three times and dried with an infrared lamp as the working electrode of the three-battery system, a saturated calomel electrode is used as the reference electrode, a platinum sheet is used as the auxiliary electrode, and the electrolyte is a 0.5 M H2SO4 solution. The OER performance of the working electrode loaded with different catalyst dispersions is tested at room temperature. Before the electrochemical OER test, the electrode is activated by 20 cycles of CV. The LSV curves were obtained in the voltage range of 1.06~1.55 V (relative to the reversible hydrogen electrode) at a scanning rate of 5 mV / s at a speed of 2500 rpm, and the data were collected after the scanning current was stable.

[0036] Figure 3The LSV curves of the supported Ir / TaB2 catalyst prepared in Example 1 and the commercial iridium black catalyst in Comparative Example 1 under acidic conditions are compared. It can be seen that at a current density of 10 mAcm -2 When the supported Ir / TaB2 catalyst prepared in Example 1 has a smaller overpotential than the commercial iridium black catalyst in Comparative Example 1, it is shown that the supported Ir / TaB2 catalyst prepared in the present invention has better acidic oxygen evolution reaction activity than the commercial iridium-based catalyst.

[0037] Figure 4 The stability test effect diagram of the supported Ir / TaB2 catalyst prepared in Example 1 is shown in Figure 1. After CV cycles of 30,000 cycles, the catalyst exhibited a stable performance at a current density of 10 mA cm -2 When , the overpotential increased by only 22 mV.

[0038] Table 1 shows the catalysts prepared by the supported Ir / TaB2 catalysts of Examples 1 to 5, the commercial iridium black catalyst of Comparative Example 1, and the commercial iridium oxide catalyst of Comparative Example 2 at a current density of 10 mA cm -2 The initial overpotential at 10000 cycles and the final overpotential after 30,000 cycles are shown in Table 1. The initial overpotentials of the supported Ir / TaB2 catalysts prepared in Examples 1 to 5 are better than those of the commercial iridium black catalyst (Comparative Example 1) and the commercial iridium oxide catalyst (Comparative Example 2). After the stability test, the increase in the final overpotential of the supported Ir / TaB2 catalysts prepared in Examples 1 to 5 compared to the initial overpotential is significantly lower than that of the commercial iridium black catalyst (Comparative Example 1) and the commercial iridium oxide catalyst (Comparative Example 2).

[0039] Table 1. Initial overpotentials of different catalysts and final overpotentials after 30,000 cycles From the above, it can be seen that the supported Ir / TaB2 catalyst provided by the present invention has a small particle size of about 3-4 nm and a uniform structure. The supported Ir / TaB2 catalysts prepared in all embodiments have achieved significant results in OER reactions, with a current density of 10 mA cm -2The initial overpotential is less than 260 mV; in particular, the supported Ir / TaB2 catalyst prepared in Example 1 has an overpotential of only 220 mV, which is far superior to the commercial iridium-based catalyst. The supported Ir / TaB2 catalyst provided by the present invention also has excellent stability. The overpotential after 30,000 CV cycles of continuous testing is only increased by 22-26 mV compared with the initial overpotential. Under the same conditions, the overpotential increase of the commercial iridium black catalyst (Comparative Example 1) and the commercial iridium oxide catalyst (Comparative Example 2) is 33-40 mV, indicating that the catalyst of the present invention has both high activity and high stability.

[0040] The above is only an embodiment of the present invention, and does not limit the present invention in any form. The present invention can also have other forms of embodiments according to the above structures and functions, which are not listed one by one. Therefore, any simple modification, equivalent change and modification made by any technician familiar with the profession to the above embodiment according to the technical essence of the present invention without departing from the scope of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a supported Ir / TaB2 catalyst, characterized in that: The following steps are involved: Tantalum diboride and urea were dissolved in deionized water, ultrasonicated at room temperature for 30 to 60 min, and then iridium tetrachloride was added thereto, and ultrasonicated at room temperature for 30 to 60 min again. The reaction mixture was transferred to the lining of a high-pressure reactor for hydrothermal reaction. After the reaction was completed, the reaction product was cooled to room temperature and then vacuum dried. The dried reaction product was transferred to a porcelain boat, which was placed in a tubular furnace and calcined in an Ar / H2 atmosphere to obtain a black product. The black product was centrifuged and washed, and dried at room temperature to obtain a supported Ir / TaB2 catalyst.

2. The method for preparing a supported Ir / TaB2 catalyst as claimed in claim 1, characterized in that: The molar ratio of tantalum diboride to iridium is 1:(1~2).

3. The method for preparing a supported Ir / TaB2 catalyst according to claim 1 or 2, wherein: The molar ratio of urea to iridium is (1~4):

1.

4. The method for preparing a supported Ir / TaB2 catalyst according to claim 1, wherein The temperature of the hydrothermal reaction is 90~120℃, and the time of the hydrothermal reaction is 3~5 h.

5. The method for preparing a supported Ir / TaB2 catalyst according to claim 1, wherein: The vacuum drying temperature is 70°C and the vacuum drying time is 10 to 12 h.

6. The method for preparing a supported Ir / TaB2 catalyst according to claim 1 or 4, characterized in that: The calcination temperature is 450°C and the calcination time is 4 to 6 h.

7. The method for preparing a supported Ir / TaB2 catalyst according to claim 1, characterized in that: First, the black product was centrifugally washed 2 to 3 times with anhydrous ethanol, and then centrifugally washed 6 to 10 times with deionized water.

8. The method for preparing a supported Ir / TaB2 catalyst according to claim 1, characterized in that: The particle size of the prepared supported Ir / TaB2 catalyst is 3~4 nm, and its XRD spectrum contains characteristic peaks of elemental iridium and tantalum diboride.

9. Use of the supported Ir / TaB2 catalyst obtained by the preparation method as claimed in claim 1 as an anode catalyst in PEM water electrolysis.

Images