Ir-based intermetallic compound electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses an Ir-based intermetallic compound electrocatalyst and a preparation method and application thereof, the catalyst comprises a carrier and an intermetallic compound loaded on the carrier, the chemical formula of the intermetallic compound is IrMo (1-x) Cex, x = 0.1-0.3, the preparation method comprises the following steps: (1) uniformly mixing an iridium salt solution, a molybdenum salt solution and a cerium salt, adding water and carbon black, uniformly mixing to obtain a metal salt precursor mixed solution, and drying the mixed solution to obtain metal salt precursor loaded carbon black; and (2) performing Joule heating treatment on the precursor-loaded carbon black in an argon environment, taking out, washing and drying after the Joule heating treatment is finished, thereby obtaining a final product. The Ce element is introduced, so that the electronic structures of Ir and Mo are obviously optimized, the electro-catalytic hydrogen evolution reaction activity is enhanced, and a huge energy application prospect is shown.

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 energy form that can 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 efficient 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 substitute for Pt-based hydrogen evolution materials, but the use of high precious metal loading limits its widespread application in water electrolysis. Summary of the invention

[0003] Purpose of the invention: The first purpose 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 purpose of the present invention is to provide a method for preparing the Ir-based intermetallic compound electrocatalyst; the third purpose 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 loaded 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 increases first 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 precursor

[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 carbon black loaded with the metal salt precursor;

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

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

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

[0014] Preferably, the conditions of the Joule heating treatment are as follows: the operation of the Joule heating treatment is: 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 1 time, and the thermal shock temperature can reach 1400-1600°C according to the shock current size. 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 characteristics 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 exhibits excellent HER activity and stability, effectively improving the catalytic activity of the catalyst, and has great prospects for energy application.

[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 heating and cooling 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 synergistic effect of iridium and cerium improves the catalytic activity and stability of the catalyst; (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, uniform distribution, and 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 1M 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 1M KOH;

[0027] Figure 6 Carbon-supported Ir(Mo) doped with different amounts of rare earth 1-x Ce x ) HER performance diagram of intermetallic compound electrocatalyst in 1M 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 is further described below in conjunction with embodiments.

[0030] Example 1

[0031] 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 1.5 ml of 0.05 mol L iridium chloride solution -1 Sodium molybdate solution, 3.7 mg anhydrous CeCl 3 Ultrasonic mixing was performed to obtain a uniform mixture, and 1.5 ml of deionized water and 0.06 g of Ketjen Black EC600JD were added thereto. Ultrasonic mixing was continued to obtain a uniform mixture, and the obtained mixture 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 in 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 this condition, the Joule heating temperature was 1500°C. 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 contents are 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 consistent with 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 consistent with Example 1.

[0050] Example 10

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

[0052] Embodiment 11

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

[0054] Example 12

[0055] The difference from Example 1 is that 3.7 mg CeCl 3 Replaced with 1.75 mg CeCl 3 The rest of the contents are consistent with those in Example 1 to obtain carbon-supported Ir(Mo 0.9 Ce 0.1 )Intermetallic compound nanoparticles.

[0056] Embodiment 13

[0057] The difference from Example 1 is that 3.7 mg CeCl 3 Replaced with 5.55 mg CeCl 3 The rest of the contents are consistent with those in Example 1 to obtain carbon-supported Ir(Mo 0.7 Ce 0.3 )Intermetallic compound nanoparticles.

[0058] Embodiment 14

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

[0060] Embodiment 15

[0061] The difference from Example 1 is that 0.06 g of Ketjen Black EC600JD is replaced by 0.07 g 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 thermal current of 250A is replaced by the Joule thermal current of 260A. Under this condition, the Joule thermal temperature is 1600°C. The rest of the contents are consistent with Example 1.

[0064] Embodiment 17

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

[0066] Embodiment 18

[0067] The difference from Example 1 is that the Joule thermal current of 250A is replaced by the Joule thermal current of 230A. Under this condition, the Joule thermal temperature is 1400°C. The rest of the contents are consistent with Example 1.

[0068] Embodiment 19

[0069] The difference from Example 1 is that the rapid Joule heating time of 30 s is replaced by a rapid Joule heating time of 15 s, and the rest of the contents are consistent with Example 1.

[0070] Embodiment 20

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

[0072] Embodiment 21

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

[0074] Comparative Example 1

[0075] Based on Example 1, CeCl was not added. 3 , the other conditions remain unchanged, and carbon-supported IrMo is obtained.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that 3.7 mg CeCl 3 Replaced with 7.4 mg CeCl 3 The rest of the contents are consistent with those 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 examine the carbon-supported Ir(Mo) prepared in Example 1. 0.8 Ce 0.2 ) The intermetallic compound nanoparticles were physically characterized. 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 ) The intermetallic compound nanoparticles are evenly distributed on the carbon black carrier, and the particle size is about 4nm. The smaller particle size provides abundant active sites and improves the catalytic performance.

[0081] (2) The 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 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) The carbon-supported Ir(Mo) prepared in Example 1 0.8 Ce 0.2 ) The intermetallic compound nanoparticles were subjected to stability (IT) tests, which were performed on a CHI 760E electrochemical workstation using a three-electrode system and measuring the potential converted to a reversible hydrogen electrode.

[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 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, 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 -1.4V to -0.9V, the scan rate was 5mV / s, and all measured potentials were converted to reversible hydrogen electrodes. The results are shown in Figure 5 shown.

[0087] Depend on Figure 5 It can be seen that the catalyst prepared in Example 1 has a current density of 10 mA cm -2 The overpotential is only 19mV, which is better than the commercial Pt / C catalyst (44mV) and the comparative catalyst IrMo (28mV). The HER activity of Ce-doped IrMo nanocatalyst in alkaline electrolyte is much higher than that of commercial Pt / C, which is mainly attributed to the fact that the incorporation of Ce optimizes the electronic structure of Ir and Mo and improves its catalytic performance.

[0088] The LSV curves of Ce doping with different contents are shown in Figure 2. 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 370 °C are 19 mV, 23 mV, 27 mV, and 36 mV, respectively. With the increase of Ce doping amount, the catalytic activity first increases and then decreases. 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 1M KOH. 0.8 Ce 0.2 ) Intermetallic nanoparticles at 10 mA cm -2The ADT is performed for 10,000 scan cycles. 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 ) showed only a slight negative shift of 5 mV. 1-x Ce x )Intermetallic compound electrocatalysts have good stability in alkaline environments.

[0091] In summary, the present invention proposes for the first time to use 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 surface of carbon black, 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.

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 carbon black loaded with the metal salt precursor; (2) Joule heating to obtain intermetallic compound electrocatalysts The carbon black loaded by the precursor is subjected to Joule heating treatment in an argon environment, and after the treatment, it is taken out, washed, and dried to obtain the final product.

6. The method for preparing the Ir-based intermetallic compound electrocatalyst according to claim 5, characterized in that: 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 to 260A, the shock current time is 15 to 60 seconds, and the cooling time is set to 10 seconds, the thermal shock cycle is 1 time, and the thermal shock temperature can reach 1400 to 1600°C depending on the shock current size.

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 iridium chloride.

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.

Images