Ir-based intermetallic compound electrocatalyst and its preparation method and application

Abstract

The present invention discloses an Ir-based intermetallic compound electrocatalyst and its preparation method and application. The catalyst comprises a carrier and an intermetallic compound loaded on the carrier. The chemical formula of the intermetallic compound is IrMo 1‑x Ce x , x = 0.1 to 0.3; its preparation method comprises: (1) uniformly mixing an iridium salt solution, a molybdenum salt solution, and a cerium salt, adding water and carbon black, and uniformly mixing to obtain a metal salt precursor mixed solution, and drying the mixed solution to obtain a metal salt precursor-loaded carbon black; (2) subjecting the precursor-loaded carbon black to a Joule heating treatment under an argon atmosphere, and then removing, washing, and drying to obtain a final product. The present invention introduces the Ce element, significantly optimizing the electronic structure of Ir and Mo, enhancing the activity of the electrocatalytic hydrogen evolution reaction, and showing great prospects for energy applications.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to an Ir-based intermetallic compound electrocatalyst and a preparation method and application thereof. Background Art

[0002] Hydrogen has the characteristics of high energy density and no pollution, and is the most promising form of energy to replace fossil fuels. At present, water electrolysis technology is an effective way to produce high-quality hydrogen. It includes hydrogen evolution reaction and oxygen evolution reaction. Electrocatalytic water splitting through hydrogen evolution reaction (HER) is a feasible high-purity hydrogen production technology. Its commercial catalyst is Pt / C, but because Pt has the disadvantages of scarce reserves, slow reaction kinetics and poor stability, we need to develop other high-efficiency hydrogen evolution electrocatalysts that can replace Pt / C to promote the reaction and promote the large-scale application of water electrolysis technology. The precious metal Ir has a hydrogen bond strength similar to Pt and is not easily poisoned by hydroxyl groups. It is a potential alternative to Pt-based hydrogen evolution materials, but its use of high precious metal loading limits its widespread application in water electrolysis. Summary of the Invention

[0003] Objectives of the invention: The first objective of the present invention is to provide an Ir-based intermetallic compound electrocatalyst that improves the catalytic activity of the Ir-based intermetallic compound electrocatalyst; the second objective of the present invention is to provide a method for preparing the Ir-based intermetallic compound electrocatalyst; the third objective of the present invention is to provide an application of the Ir-based intermetallic compound electrocatalyst.

[0004] Technical solution: The Ir-based intermetallic compound electrocatalyst of the present invention comprises a carrier and an intermetallic compound supported on the carrier, wherein the chemical formula of the intermetallic compound is IrMo 1-x Ce x , x = 0.1 to 0.3. As x increases, the catalytic performance of the Ir-based intermetallic compound electrocatalyst first increases and then decreases, and the best effect is achieved when x = 0.2.

[0005] Preferably, x=0.1-0.2.

[0006] Preferably, the carrier is carbon black.

[0007] Preferably, the carbon black is Vulcan XC72, Ketjen Black EC300J or Ketjen Black EC600JD.

[0008] The method for preparing the Ir-based intermetallic compound electrocatalyst of the present invention comprises the following steps:

[0009] (1) Preparation of carbon black loaded with metal salt precursors

[0010] The iridium salt solution, the molybdenum salt solution and the cerium salt are mixed evenly, water and carbon black are added, and the mixture is mixed evenly to obtain a metal salt precursor mixed solution, and the mixed solution is dried to obtain the metal salt precursor-loaded carbon black;

[0011] (2) Joule heating to obtain intermetallic compound electrocatalysts

[0012] The carbon black loaded on the precursor is subjected to Joule heating treatment in an argon environment, and then taken out, washed, and dried to obtain the final product.

[0013] Preferably, the drying is freeze-drying.

[0014] Preferably, the Joule heating treatment conditions are as follows: the Joule heating treatment operation is as follows: the sample to be thermally shocked is laid flat on a graphite boat carrier and placed in a Joule heating device, the shock current range is 230-260A, the shock current time is 15-60 seconds, and the cooling time is set to 10 seconds, the thermal shock cycle is one, and the thermal shock temperature can reach 1400-1600°C depending on the shock current. Preferably, the iridium salt is iridium chloride, iridium acetate, or iridium sulfate.

[0015] Preferably, the molybdenum salt is sodium molybdate or ammonium molybdate.

[0016] Preferably, the cerium salt is cerium chloride, cerium nitrate or cerium sulfate.

[0017] Application of the Ir-based intermetallic compound electrocatalyst of the present invention in hydrogen evolution reaction.

[0018] Invention mechanism:

[0019] Ce element has attracted wide attention in optimizing the electronic structure of materials and improving the catalytic performance of materials due to its variable coordination number and unique electronic properties of the 4f orbital. 1-x Ce x ) intermetallic compound electrocatalyst, successfully introduced Ce into IrMo intermetallic compound, and further optimized the electronic structure of Ir and Mo through the unique 4f orbital electrons of Ce element, so that it exhibited excellent HER activity and stability, effectively improving the catalytic activity of the catalyst, and has great energy application prospects.

[0020] Converting disordered Ir-M intermetallic compounds into ordered intermetallic compounds can effectively delay the leaching of M in Ir-M intermetallic compounds, but its synthesis process is often more complicated, such as requiring continuous high-temperature heating and long-term annealing. Joule heating technology has ultra-high reaction temperature, ultra-fast temperature rise and fall speed, and extremely short reaction time. At the same time, controlling the synthesis of the catalyst by Joule heating can solve the particle size and distribution problems existing in traditional preparation methods, showing considerable advantages. Compared with the traditional thermal annealing preparation method, the method of the present invention can prepare Ir(Mo) in a short time. 1-x Ce x ) intermetallic compounds and successfully introduced the Ce element into the system.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The intermetallic compound electrocatalyst is doped with cerium in the IrMo intermetallic compound, and the catalytic activity and stability of the catalyst are improved under the synergistic effect of iridium and cerium; (2) Joule heat is used to prepare the IrMo intermetallic compound, and a small amount of cerium is added to the precursor to replace molybdenum to construct the intermetallic compound electrocatalyst, and the preparation method is simple and fast; (3) The intermetallic compound electrocatalyst prepared by this method can be uniformly loaded on a carbon black substrate, has a small particle size and uniform distribution, has a large number of active sites, and exhibits relatively excellent electrocatalytic activity in HER. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention 1-x Ce x ) High-resolution transmission electron microscopy (HRTEM) images of intermetallic compound electrocatalysts;

[0023] Figure 2 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention 1-x Ce x ) Particle size distribution of intermetallic compound electrocatalysts;

[0024] Figure 3 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention 1-x Ce x ) X-ray diffraction (XRD) patterns of intermetallic compound electrocatalysts;

[0025] Figure 4 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention 1-x Ce x ) Stability (IT) curve of intermetallic compound electrocatalyst in 1 M KOH;

[0026] Figure 5 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention1-x Ce x ) HER performance diagram of intermetallic compound electrocatalyst in 1 M KOH;

[0027] Figure 6 Carbon-supported Ir(Mo 1-x Ce x ) HER performance diagram of intermetallic compound electrocatalyst in 1 M KOH;

[0028] Figure 7 Carbon-supported Ir(Mo) prepared in Example 1 of the present invention 1-x Ce x ) Stability (ADT) test curve of intermetallic compound electrocatalyst in 1M KOH. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0030] Example 1

[0031] The preparation method of the Ir-based intermetallic compound electrocatalyst of the present invention comprises the following steps:

[0032] (1) Add 1.5 mL of 0.05 mol L -1 iridium chloride solution, 1.5 ml 0.05 mol L -1 Sodium molybdate solution and 3.7 mg of anhydrous CeCl3 were ultrasonically mixed, 1.5 ml of deionized water and 0.06 g of Ketjen Black EC600JD were added thereto, and ultrasonic mixing was continued to obtain a mixed solution. The obtained mixed solution was freeze-dried to obtain carbon black loaded with a metal salt precursor;

[0033] (2) The carbon black loaded with the metal salt precursor was spread flat on a graphite boat, and then placed in a Joule heating device. The Joule heating current was set to 250A, the rapid Joule heating time was set to 30s, and the cooling time was set to 10s. The thermal shock cycle was 1 time. Under these conditions, the Joule heating temperature was 1500℃. After the thermal shock, the sample was taken out, washed and dried to obtain carbon-loaded Ir(Mo 0.8 Ce 0.2 )Intermetallic compound nanoparticles.

[0034] Example 2

[0035] The difference from Example 1 is that iridium chloride is replaced by iridium acetate, and the rest of the content is consistent with Example 1.

[0036] Example 3

[0037] The difference from Example 1 is that iridium chloride is replaced by iridium acetylacetonate, and the rest of the content is consistent with Example 1.

[0038] Example 4

[0039] The difference from Example 1 is that iridium chloride is replaced by chloroiridic acid, and the rest of the content is consistent with Example 1.

[0040] Example 5

[0041] The difference from Example 1 is that sodium molybdate is replaced by ammonium molybdate, and the rest of the contents are the same as in Example 1.

[0042] Example 6

[0043] The difference from Example 1 is that sodium molybdate is replaced by molybdenum acetylacetonate, and the rest of the content is consistent with Example 1.

[0044] Example 7

[0045] The difference from Example 1 is that sodium molybdate is replaced by platinum chloride, and the rest of the content is consistent with Example 1.

[0046] Example 8

[0047] The difference from Example 1 is that cerium chloride is replaced by cerium nitrate, and the rest of the contents are the same as those in Example 1.

[0048] Example 9

[0049] The difference from Example 1 is that cerium chloride is replaced by cerium acetylacetonate, and the rest of the contents are the same as those in Example 1.

[0050] Example 10

[0051] The difference from Example 1 is that Ketjen Black EC600JD is replaced with Ketjen Black EC300J, and the rest of the content is consistent with Example 1.

[0052] Example 11

[0053] The difference from Example 1 is that Ketjen Black EC600JD is replaced with Vulcan XC72, and the rest of the contents are the same as Example 1.

[0054] Example 12

[0055] The difference from Example 1 is that 3.7 mg CeCl3 is replaced by 1.75 mg CeCl3, and the rest of the contents are the same as in Example 1 to obtain carbon-supported Ir(Mo 0.9 Ce 0.1 )Intermetallic compound nanoparticles.

[0056] Example 13

[0057] The difference from Example 1 is that 3.7 mg CeCl3 is replaced by 5.55 mg CeCl3, and the rest of the contents are the same as in Example 1 to obtain carbon-supported Ir(Mo 0.7 Ce 0.3 )Intermetallic compound nanoparticles.

[0058] Example 14

[0059] The difference from Example 1 is that 0.06g of Ketjen Black EC600JD is replaced by 0.05g of Ketjen Black EC600JD, and the rest of the content is consistent with Example 1.

[0060] Example 15

[0061] The difference from Example 1 is that 0.06g of Ketjen Black EC600JD is replaced by 0.07g of Ketjen Black EC600JD, and the rest of the content is consistent with Example 1.

[0062] Example 16

[0063] The difference from Example 1 is that the Joule heating current of 250A is replaced by the Joule heating current of 260A. Under this condition, the Joule heating temperature is 1600°C. The rest of the contents are consistent with Example 1.

[0064] Example 17

[0065] The difference from Example 1 is that the Joule heating current of 250A is replaced by the Joule heating current of 240A. Under this condition, the Joule heating temperature is 1450°C. The rest of the contents are consistent with Example 1.

[0066] Example 18

[0067] The difference from Example 1 is that the Joule heating current of 250A is replaced by the Joule heating current of 230A. Under this condition, the Joule heating temperature is 1400°C. The rest of the contents are the same as those in Example 1.

[0068] Example 19

[0069] The difference from Example 1 is that the rapid Joule heating time of 30s is replaced by the rapid Joule heating time of 15s, and the rest of the contents are the same as those in Example 1.

[0070] Example 20

[0071] The difference from Example 1 is that the rapid Joule heating time of 30s is replaced by the rapid Joule heating time of 45s, and the rest of the contents are consistent with Example 1.

[0072] Example 21

[0073] The difference from Example 1 is that the rapid Joule heating time is changed from 30s to 60s, and the rest of the contents are the same as those in Example 1.

[0074] Comparative Example 1

[0075] On the basis of Example 1, CeCl 3 was not added, and other conditions remained unchanged to obtain carbon-supported IrMo.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that 3.7 mg CeCl3 is replaced by 7.4 mg CeCl3, and the rest of the contents are the same as in Example 1 to obtain carbon-supported Ir(Mo 0.6 Ce 0.4 )Intermetallic compound nanoparticles.

[0078] Structural characterization

[0079] (1) High resolution transmission electron microscopy (HRTEM) was used to observe the carbon-supported Ir(Mo) prepared in Example 1. 0.8 Ce 0.2 )Intermetallic compound nanoparticles were physically characterized, and the results were as follows Figure 1 and Figure 2 shown.

[0080] Depend on Figure 1 and Figure 2 It can be seen that the Ir(Mo) prepared by the preparation method of the present invention 0.8 Ce 0.2 ) Intermetallic compound nanoparticles are evenly distributed on the carbon black carrier, with a particle size of about 4 nm. The smaller particle size provides abundant active sites and improves the catalytic performance.

[0081] (2) Carbon-supported Ir(Mo) prepared in Example 1 0.8 Ce 0.2 ) and IrMo intermetallic compound nanoparticles were subjected to X-ray diffraction test to obtain XRD spectra. The results are as follows Figure 3 shown.

[0082] Depend on Figure 3 It can be obtained that Ir(Mo 0.8 Ce 0.2 ) The diffraction peaks of the intermetallic compound nanoparticles correspond to those of the IrMo intermetallic compound standard card (PDF#97-010-4499) and are slightly offset, indicating that the incorporation of Ce does not change the phase structure of IrMo and may cause lattice expansion.

[0083] Performance Testing

[0084] (1) Carbon-supported Ir(Mo) prepared in Example 1 0.8Ce 0.2 The stability (IT) tests of the intermetallic compound nanoparticles were performed on a CHI 760E electrochemical workstation using a three-electrode system and a reversible hydrogen electrode for measuring the potential.

[0085] Depend on Figure 4 It can be seen that the prepared Ir(Mo 0.8 Ce 0.2 ) Intermetallic compound nanoparticles have good stability under 1M KOH alkaline conditions.

[0086] (2) Commercial Pt / C was used as a reference catalyst, and the carbon-supported Ir(Mo) prepared in Example 1, Examples 12-13 and Comparative Example 2 was subjected to 1M KOH. 1-x Ce x ) intermetallic compound, the carbon-supported IrMo intermetallic compound prepared in Comparative Example 1, and commercial Pt / C were subjected to linear sweep voltammetry (LSV) tests on a CHI 760E electrochemical workstation using a three-electrode system. The test voltage range was -1.4 V to -0.9 V, the scan rate was 5 mV / s, and all measured potentials were converted to reversible hydrogen electrodes. The results are shown in Figure 2. Figure 5 shown.

[0087] Depend on Figure 5 It can be seen that the catalyst prepared in Example 1 has a high current density of 10 mA cm -2 The overpotential at 19 mV is superior to that of commercial Pt / C catalysts (44 mV) and IrMo (28 mV). Ce-doped IrMo nanocatalysts exhibit significantly higher HER activity than commercial Pt / C in alkaline electrolytes, primarily due to the Ce incorporation optimizing the electronic structures of Ir and Mo, thus enhancing their catalytic performance.

[0088] The LSV curves of different Ce doping contents are as follows Figure 6 The catalysts prepared in Example 1, Examples 12-13 and Comparative Example 2 were heated to a current density of 10 mA cm -2 The overpotentials at these times are 19mV, 23mV, 27mV, and 36mV, respectively. With the increase of Ce doping amount, the catalytic activity first increases and then decreases. Among them, the best HER activity is exhibited when the molar ratio of Ce to Ir is 0.2.

[0089] (3) The carbon-supported Ir(Mo) prepared in Example 1 was subjected to a 1 M KOH reaction. 0.8 Ce 0.2 ) Intermetallic compound nanoparticles at 10 mA cm -2 The ADT is performed for 10,000 scan cycles, and the results are as follows Figure 7 shown.

[0090] Depend on Figure 7 It can be seen that Ir(Mo 0.8 Ce 0.2 )'s HER curve showed only a slight negative shift of 5 mV, and the prepared Ir(Mo 1-x Ce x )Intermetallic compound electrocatalysts have good stability in alkaline environment.

[0091] In summary, the present invention proposes for the first time the use of Joule heating to prepare Ir(Mo 1-x Ce x ) intermetallic compound electrocatalyst, the preparation method is simple and fast, and can be prepared in a short time with high throughput. The prepared intermetallic compound electrocatalyst nanoparticles are uniformly loaded on the carbon black surface, with a uniform size of about 4nm, and show excellent HER electrocatalytic activity.

Claims

1. An Ir-based intermetallic compound electrocatalyst, characterized in that The catalyst comprises a carrier and an intermetallic compound supported on the carrier, wherein the chemical formula of the intermetallic compound is IrMo 1-x Ce x , x=0.1~0.3; the preparation method comprises the following steps: (1) Preparation of carbon black loaded with metal salt precursor The iridium salt solution, the molybdenum salt solution and the cerium salt are mixed evenly, water and carbon black are added, and the mixture is mixed evenly to obtain a metal salt precursor mixed solution, and the mixed solution is dried to obtain the metal salt precursor-loaded carbon black; (2) Joule heating to obtain intermetallic compound electrocatalysts The carbon black loaded with the precursor is subjected to Joule heating treatment in an argon environment, and then taken out, washed, and dried to obtain a final product; the conditions of the Joule heating treatment are as follows: the operation of the Joule heating treatment is as follows: the sample to be thermally shocked is laid flat on a graphite boat carrier and placed in a Joule heating device, the shock current range is 230~260 A, the shock current time is 15~60 seconds, and the cooling time is set to 10 seconds, and the thermal shock cycle is 1 time.

2. The Ir-based intermetallic compound electrocatalyst according to claim 1, characterized in that The x=0.1~0.

2.

3. The Ir-based intermetallic compound electrocatalyst according to claim 1, characterized in that The carrier is carbon black.

4. The Ir-based intermetallic compound electrocatalyst according to claim 3, characterized in that The carbon black is VulcanXC72, Ketjen Black EC300J or Ketjen Black EC600JD.

5. A method for preparing the Ir-based intermetallic compound electrocatalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preparation of carbon black loaded with metal salt precursor The iridium salt solution, the molybdenum salt solution and the cerium salt are mixed evenly, water and carbon black are added, and the mixture is mixed evenly to obtain a metal salt precursor mixed solution, and the mixed solution is dried to obtain the metal salt precursor-loaded carbon black; (2) Joule heating to obtain intermetallic compound electrocatalysts The carbon black loaded with the precursor is subjected to Joule heating treatment in an argon environment, and then taken out, washed, and dried to obtain a final product; the conditions of the Joule heating treatment are as follows: the operation of the Joule heating treatment is as follows: the sample to be thermally shocked is laid flat on a graphite boat carrier and placed in a Joule heating device, the shock current range is 230~260 A, the shock current time is 15~60 seconds, and the cooling time is set to 10 seconds, and the thermal shock cycle is 1 time.

6. The method for preparing the Ir-based intermetallic compound electrocatalyst according to claim 5, characterized in that: The thermal shock temperature of the Joule heating treatment can reach 1400-1600° C. depending on the magnitude of the shock current.

7. The method for preparing the Ir-based intermetallic compound electrocatalyst according to claim 5, characterized in that: The iridium salt is iridium chloride, iridium acetate, iridium acetylacetonate or chloroiridic acid.

8. The method for preparing the Ir-based intermetallic compound electrocatalyst according to claim 5, characterized in that: The molybdenum salt is sodium molybdate, ammonium molybdate, molybdenum acetylacetonate or molybdenum chloride.

9. The method for preparing the Ir-based intermetallic compound electrocatalyst according to claim 5, characterized in that: The cerium salt is cerium chloride, cerium nitrate or cerium acetylacetonate.

10. Use of the Ir-based intermetallic compound electrocatalyst according to any one of claims 1 to 4 in a hydrogen evolution reaction.

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