Monatomic iridium-based alloy cluster catalyst as well as preparation method and electro-catalysis application thereof

Abstract

The invention belongs to the technical field of electrochemistry, and provides a monatomic iridium-based alloy cluster catalyst and a preparation method and electrocatalysis application thereof, and the preparation method comprises the following steps: low-pressure gas-phase capillary filling: mixing an iridium organic metal precursor, a dopant metal organic precursor, a microporous carrier material and a solvent, and drying to obtain mixed powder, the mixed powder is placed in an ampoule bottle with a certain vacuum degree and sealed, then the ampoule bottle is placed in a rotary drying oven for high-temperature heat treatment, and powder a is obtained; temperature-controlled acid etching: mixing the powder a and an acid solution for reaction in the environment of protective gas to obtain black powder; the black powder is placed in H2 / Ar mixed gas for programmed heat treatment, and the monatomic iridium-based alloy cluster catalyst is obtained. The monatomic iridium-based alloy cluster catalyst prepared by the method provided by the invention shows mass activity and catalytic durability which are obviously superior to those of commercial platinum carbon in alkaline hydroxide catalysis, and has a practical application prospect.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to a single-atom iridium-based alloy cluster catalyst, a preparation method thereof, and electrocatalytic applications. Background Art

[0002] As a clean and efficient energy conversion technology, hydrogen fuel cells have the characteristics of high energy density and zero emissions, and are an important technical approach to solving the global energy crisis and environmental pollution problems. In particular, anion exchange membrane fuel cells (AEMFCs) have become one of the important research directions of hydrogen energy technology in recent years because they can operate efficiently in alkaline environments and have lower costs, stronger fuel adaptability, higher durability and a wider operating temperature range than proton exchange membrane hydrogen fuel cells.

[0003] The anode reaction of anion exchange membrane hydrogen fuel cells is mainly the hydrogen oxidation reaction (HOR), and the kinetic characteristics of this reaction are crucial to the efficiency and stability of the battery. In an alkaline environment, the hydrogen oxidation reaction often exhibits a slow reaction rate, which requires the anode catalyst to have high catalytic activity and good durability. Traditional platinum-based catalysts are limited in their wide application due to their slow alkaline HOR catalytic kinetics, poor anti-poisoning and poor corrosion resistance. In order to solve this problem, iridium-based catalysts have become a research hotspot for hydrogen fuel cell anode catalysts due to their excellent catalytic performance, strong anti-poisoning and good stability. In particular, iridium cluster catalysts can provide more active sites and higher atomic utilization, thereby significantly improving the efficiency of the catalytic reaction under the premise of controllable cost. However, a single iridium active site is often difficult to meet the competitive adsorption requirements of alkaline HOR catalysis for multiple reaction intermediates, and the synthesis method and catalytic performance of iridium-based catalysts still face some challenges, especially in terms of catalyst particle size control, alloy element distribution and catalytic stability.

[0004] As a new type of catalytic material, single-atom iridium-based alloy cluster catalysts can further optimize the electronic structure of the catalyst, improve the catalytic activity, enhance the stability of the catalyst, and avoid the aggregation and oxidation of metal particles by introducing other transition metals into the iridium-based catalyst through alloying. Compared with traditional nanoparticle catalysts, single-atom iridium-based alloy cluster catalysts usually show higher catalytic efficiency and selectivity in catalytic reactions due to their highly dispersed active sites. Most current catalyst synthesis methods rely on high temperature and high pressure conditions, or require complex solution chemistry processes, which not only makes the synthesis process complicated and costly, but also limits the large-scale production of catalysts. Therefore, the development of a simple, low-cost and efficient preparation method for single-atom iridium-based alloy cluster catalysts will be able to significantly improve the performance of the catalyst and promote its widespread application in the field of hydrogen fuel cells.

[0005] In summary, for the alkaline hydrogen oxidation reaction at the anode of an anion exchange membrane hydrogen fuel cell, how to develop an efficient and stable single-atom iridium-based alloy cluster catalyst has become an important topic in current catalytic research. The preparation method and application research of such catalysts can not only promote the commercialization process of hydrogen fuel cell technology but also provide new ideas for the design and synthesis of catalytic materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a single-atom iridium-based alloy cluster catalyst, its preparation method, and electrocatalytic application. The technical problem to be solved is to provide a new method for precisely controlling the uniformity of the iridium-based alloy in cluster size and the single-atom form of the doped components, adopting a two-step collaborative preparation method of "low-pressure gas-phase capillary filling - temperature-controlled acid etching".

[0007] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method of a single-atom iridium-based alloy cluster catalyst, comprising the following steps:

[0009] (1) Low-pressure gas-phase capillary filling: Mix an iridium organometallic precursor, a dopant organometallic precursor, a microporous support material, and a solvent and dry them to obtain a mixed powder. Place the mixed powder in an ampoule bottle under a certain vacuum and seal it, and then place it in a rotary oven for high-temperature heat treatment to obtain powder a;

[0010] (2) Temperature-controlled acid etching: Under the environment of a protective gas, mix powder a and an acid solution for reaction to obtain a black powder; subject the black powder to programmed heat treatment in a H2 / Ar mixed gas to obtain the single-atom iridium-based alloy cluster catalyst.

[0011] Preferably, in step (1), the mass-volume ratio of the iridium organometallic precursor, the dopant organometallic precursor, the microporous support material, and the solvent is 20 - 60 mg: 20 - 60 mg: 60 - 100 mg: 5 - 15 mL.

[0012] Preferably, in step (1), the dopant organometallic precursor is one or more of a tin-based organic complex, a vanadium-based organic complex, a manganese-based organic complex, a gallium-based organic complex, and an indium-based organic complex;

[0013] In step (1), the microporous support material is one or more of porous carbon, silicon carbide, metal-organic framework material, and conjugated organic framework material;

[0014] In step (1), the solvent is acetone.

[0015] Preferably, the vacuum degree in the step (1) is 10 -3 ~10 -5 mbar;

[0016] The rotation speed of the rotary oven in the step (1) is 10 - 100 rpm;

[0017] The temperature of the high-temperature heat treatment in the step (1) is 100 - 300 °C, and the time of the high-temperature heat treatment is 5 - 48 h.

[0018] Preferably, the acid solution in the step (2) is one or more of sulfuric acid solution, hydrochloric acid solution and nitric acid solution;

[0019] The concentration of the acid solution in the step (2) is 0.05 - 0.2 mol / L.

[0020] Preferably, the temperature of the mixing reaction in the step (2) is 50 - 90 °C, and the time of the mixing reaction is 8 - 12 h.

[0021] Preferably, the concentration of the H2 / Ar mixed gas in the step (2) is 3 - 20%.

[0022] Preferably, the temperature of the programmed heat treatment in the step (2) is 150 - 200 °C, and the time of the programmed heat treatment is 1 - 3 h.

[0023] The present application also provides a single-atom iridium-based alloy cluster catalyst prepared by the preparation method of a single-atom iridium-based alloy cluster catalyst.

[0024] The present application also provides an application of a single-atom iridium-based alloy cluster catalyst as a catalyst for hydrogen oxidation reaction at the anode of an alkaline hydrogen fuel cell.

[0025] The present invention has the following beneficial effects:

[0026] 1. Through low-pressure gas-phase capillary filling, the iridium and doped metal organic precursors are sublimated and then mixed in the gas phase. The low-pressure and high-temperature environment induces alloying through entropy driving, which can increase the driving force of the alloying reaction, solve the thermodynamic incompatibility between multiple metals, and reduce the phase separation phenomenon between metals.

[0027] 2. The present invention selects a microporous carrier as the confinement material for the clusters, and uses the nanoscale macroscopic confinement of the microporous structure to form iridium-based metal clusters, realizing precise size control of the metal clusters.

[0028] 3. The present invention utilizes a temperature-controlled acid etching technique to selectively remove excess doped metal elements, optimize the metal distribution on the catalyst surface, and regulate the particle size, morphology, and dispersion of the metal, which helps to improve the catalytic performance and achieve the rapid, uniform, and large-scale preparation of single-atom iridium-based alloy cluster catalysts.

[0029] 4. The single-atom iridium-based alloy cluster catalyst prepared by the method provided by the present invention exhibits significantly better mass activity and catalytic durability than commercial platinum carbon in alkaline hydrogen oxidation catalysis and has practical application prospects. Description of the Drawings

[0030] Figure 1 It is the aberration-corrected STEM image of the single-atom iridium-based alloy cluster catalyst of Example 1;

[0031] Figure 2 It is the EDS mapping image of the single-atom iridium-based alloy cluster catalyst of Example 1;

[0032] Figure 3 It is the EDS energy spectrum of the single-atom iridium-based alloy cluster catalyst of Example 1;

[0033] Figure 4 It is the line scan analysis image of the single-atom iridium-based alloy cluster catalyst of Example 1;

[0034] Figure 5 It is the Sn K-edge EXAFS spectrum of the single-atom iridium-based alloy cluster catalyst of Example 1;

[0035] Figure 6 It is the XRD spectrum of the single-atom iridium-based alloy cluster catalysts of Examples 1 to 3;

[0036] Figure 7 It is the HOR polarization curve of the single-atom iridium-based alloy cluster catalysts of Examples 1, 2, 5, 7, and the comparative example at 1600 rpm in 0.1 mol / L KOH saturated with hydrogen;

[0037] Figure 8 It is the HOR polarization curve of the single-atom iridium-based alloy cluster catalyst of Example 1 at different rotation speeds in 0.1 mol / L KOH saturated with hydrogen;

[0038] Figure 9 It is the relative current-time response curve of the single-atom iridium-based alloy cluster catalyst of Example 1 and 20% commercial Pt / C in 0.1 mol / L KOH solution saturated with hydrogen;

[0039] Figure 10 It is the TEM image of the single-atom iridium-based alloy cluster catalyst of Example 3. Detailed implementation mode

[0040] The present invention provides a preparation method of a single-atom iridium-based alloy cluster catalyst, which comprises the following steps:

[0041] (1) Low-pressure gas-phase capillary filling: Mix an iridium organometallic precursor, a dopant organometallic precursor, a microporous carrier material and a solvent and dry them to obtain a mixed powder. Place the mixed powder in an ampoule bottle with a certain vacuum degree and seal it, and then place it in a rotary oven for high-temperature heat treatment to obtain powder a;

[0042] (2) Temperature-controlled acid etching: Under the environment of a protective gas, mix and react powder a with an acid solution to obtain a black powder; Subject the black powder to programmed heat treatment in a H2 / Ar mixed gas, and the single-atom iridium-based alloy cluster catalyst is obtained.

[0043] In the present invention, the low-pressure and high-temperature environment in the reaction system of step (1) can increase the driving force of the alloying reaction between multiple metals, solve the general thermodynamic incompatibility between dissimilar metals, and carry out high-temperature heat treatment for a specific time at a certain rotation speed and temperature, so that the organoiridium complex and the dopant organometallic precursor can sublime and then be mixed in the gas phase, and capillary fill the microporous structure of the carrier.

[0044] In the present invention, by the method of temperature-controlled acid etching in step (2), most of the dopant metals in the surface and bulk phase are etched away, and only a trace amount of metal dopant in the iridium lattice is retained, forming a single-atom iridium-based alloy cluster with more exposed active sites, realizing precise control of the iridium-based alloy cluster in terms of size, content and morphology of the dopant metal, etc.

[0045] In the present invention, the mass-volume ratio of the iridium organometallic precursor, the dopant organometallic precursor, the microporous carrier material and the solvent in step (1) is preferably 20-60 mg: 20-60 mg: 60-100 mg: 5-15 mL, more preferably 25-55 mg: 25-55 mg: 65-95 mg: 7-13 mL, and even more preferably 30-50 mg: 30-50 mg: 70-90 mg: 9-11 mL.

[0046] In the present invention, the dopant organometallic precursor in step (1) is preferably one or more of a tin-based organic complex, a vanadium-based organic complex, a manganese-based organic complex, a gallium-based organic complex and an indium-based organic complex.

[0047] In the present invention, the microporous carrier material in step (1) is preferably one or more of porous carbon, silicon carbide, metal-organic framework material and conjugated organic framework material.

[0048] In the present invention, the solvent in the step (1) is preferably acetone.

[0049] In the present invention, the vacuum degree in the step (1) is preferably 10 -3 ~10 -5 mbar.

[0050] In the present invention, the rotation speed of the rotary oven in the step (1) is preferably 10 - 100 rpm, more preferably 20 - 90 rpm, and even more preferably 30 - 80 rpm.

[0051] In the present invention, the temperature of the high-temperature heat treatment in the step (1) is preferably 100 - 300 °C, more preferably 120 - 280 °C, and even more preferably 150 - 250 °C.

[0052] In the present invention, the time of the high-temperature heat treatment is preferably 5 - 48 h, more preferably 8 - 45 h, and even more preferably 10 - 42 h.

[0053] In the present invention, the protective gas in the step (2) is preferably Ar gas.

[0054] In the present invention, the acid solution in the step (2) is preferably one or more of sulfuric acid solution, hydrochloric acid solution, and nitric acid solution.

[0055] In the present invention, the concentration of the acid solution in the step (2) is preferably 0.05 - 0.2 mol / L, more preferably 0.07 - 0.18 mol / L, and even more preferably 0.1 - 0.15 mol / L.

[0056] In the present invention, the temperature of the mixing reaction in the step (2) is preferably 50 - 90 °C, more preferably 55 - 85 °C, and even more preferably 60 - 80 °C.

[0057] In the present invention, the time of the mixing reaction is preferably 8 - 12 h, more preferably 8.5 - 11.5 h, and even more preferably 9 - 11 h.

[0058] In the present invention, after the mixing reaction in the step (2), a black powder is obtained. The black powder needs to be washed with deionized water until neutral and dried, and then placed in a H2 / Ar mixed gas for programmed heat treatment.

[0059] In the present invention, the concentration of the H2 / Ar mixed gas in the step (2) is preferably 3 - 20%, more preferably 5 - 18%, and even more preferably 10 - 15%.

[0060] In the present invention, the temperature of the programmed heat treatment in the step (2) is preferably 150 - 200 °C, more preferably 160 - 190 °C, and even more preferably 170 - 180 °C.

[0061] In the present invention, the time of the programmed heat treatment is preferably 1 to 3 h, more preferably 1.2 to 2.8 h, and still more preferably 1.5 to 2.5 h.

[0062] The present invention adopts a two-step collaborative preparation method of "low-pressure gas-phase capillary filling - temperature-controlled acid etching", and neither step can be missing. Low-pressure gas-phase synthesis is carried out in a sealed ampoule under vacuum and high temperature, where the organic iridium complex and the doped metal-organic precursor are sublimated and then mixed in the gas phase. The low-pressure and high-temperature environment can increase the driving force of the alloying reaction between multiple metals and solve the general thermodynamic incompatibility between dissimilar metals. After the reaction, due to the confinement effect of the microporous support and the gas-phase capillary filling effect, iridium-based alloy clusters are formed. Then, by means of temperature-controlled acid etching, most of the doped metals in the surface and bulk are etched away, and only a trace amount of doped metals in the iridium lattice are retained, forming single-atom iridium-based alloy clusters with more exposed active sites, realizing precise control of the iridium-based alloy clusters in terms of size, content and morphology of the doped metals.

[0063] The present invention also provides a single-atom iridium-based alloy cluster catalyst prepared by the preparation method of a single-atom iridium-based alloy cluster catalyst.

[0064] In the present invention, under the confinement of a specific microporous support material, the particle size of the obtained single-atom iridium alloy clusters is preferably controlled within the range of 1 to 2 nm.

[0065] In the present invention, the prepared iridium alloy clusters contain two metal components, and the doped metal is in the form of single atoms.

[0066] The present invention also provides an application of a single-atom iridium-based alloy cluster catalyst as a catalyst for the hydrogen oxidation reaction at the anode of an alkaline hydrogen fuel cell.

[0067] The technical solutions provided by the present invention will be described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0068] Example 1

[0069] Weigh 40 mg of iridium acetylacetonate, 40 mg of tin acetylacetonate, and 80 mg of Ketjenblack porous carbon, mix them with 10 mL of acetone under ultrasonic waves for 30 min, and then dry and evaporate the acetone from the mixed solution to obtain a mixed powder. Transfer the mixed powder into an open quartz ampoule, and use a molecular pump to reduce the pressure of the ampoule to 10 -5After reaching the mbar vacuum, immediately seal the ampoule neck by high-temperature melting to form a vacuum-tight environment. Then place the sealed ampoule in a rotary oven, set the rotation speed to 20 rpm, and perform high-temperature heat treatment at 250 °C for 10 h to obtain powder a. In an Ar gas environment, mix and react powder a with a sulfuric acid solution with a concentration of 0.1 mol / L at 80 °C for 10 h to obtain a black powder. Wash the black powder with deionized water until neutral, and then dry it under vacuum. Place the dried black powder in a 5% H2 / Ar mixed gas and perform programmed heat treatment at 180 °C for 2 h to obtain the single-atom iridium-based alloy cluster catalyst.

[0070] Use the product material obtained in this example as an alkaline hydrogen oxidation catalytic material and conduct electrochemical tests: The composition of the catalyst ink includes the single-atom iridium-based alloy cluster catalyst of this example, distilled water, isopropanol, and a 5 wt.% Nafion solution; the dosage ratio of the single-atom iridium-based alloy cluster catalyst, isopropanol, and 5 wt.% Nafion solution in this example is 2 mg: 980 μL: 20 μL; the coating amount of the catalyst ink on the electrode is determined according to the iridium loading amount of the anode.

[0071] Figure 1 This is the aberration-corrected STEM image of the catalyst in this example.

[0072] From Figure 1 it can be seen that the clusters formed by the product of this example are uniformly distributed in the carrier, and the particle size is concentrated at about 1.5 nm, showing typical small metal cluster characteristics.

[0073] Figure 2 the EDS mapping of Figure 3 the EDS energy spectrum of Figure 4 and the line scan analysis of Figure 5 prove that the components of the metal clusters include Ir and Sn components, and the Sn and Ir elements show a spatial coexistence distribution characteristic. ICP-OES analysis shows that the Ir element content in the catalyst obtained in Example 1 is 9.87 wt.%, and the Sn element content is 2.71 wt.% (see Table 1 below). Figure 8 This is the HOR polarization curve of the catalyst in this example at different rotation speeds in 0.1 mol / L KOH saturated with hydrogen. According to Figure 8 the results in Figure 9The relative current-time response curves of the catalyst prepared in this example and 20% commercial Pt / C in a hydrogen-saturated 0.1 mol / L KOH solution. According to Figure 9 It can be seen that after a long-term chronoamperometry test, the activity decay rate of the catalyst prepared in this example is 0.6%, while in the same test environment, the activity decay rate of 20% commercial Pt / C reaches 19.5%. This indicates that the catalyst prepared in this example can significantly improve the anti-aggregation ability of Ir metal and enhance the durability of the catalyst.

[0074] Example 2

[0075] The implementation method of this example is basically the same as that of Example 1, except that tin acetylacetonate is replaced by vanadyl acetylacetonate.

[0076] The iridium-based single-atom alloy cluster catalyst prepared in Example 2 was subjected to electrochemical testing with the same parameter settings as in Comparative Document 1. ICP-OES showed that its Ir content was 10.52 wt.%, and the V metal content was 1.19 wt.% (see Table 1 below).

[0077] Example 3

[0078] The implementation method of this example is basically the same as that of Example 1, except that the vacuum degree is set to 10 -3 mbar.

[0079] The iridium-based single-atom alloy cluster catalyst prepared in Example 3 was subjected to electrochemical testing with the same parameter settings as in Comparative Document 1. ICP-OES showed that its Ir content was 7.84 wt.%, and the Sn metal content was 1.89 wt.% (see Table 1 below). Figure 10 The TEM image of shows that the particle size of the metal clusters synthesized in this example is about 3 nm, indicating that the vacuum degree can significantly affect the particle size of iridium metal clusters. The catalyst prepared in this example has a high apparent response current density in the mixed control region, and its mass activity reaches 3251 A / g (see Table 2 below).

[0080] Figure 6 XRD patterns of the catalysts prepared in Examples 1 to 3. From Figure 6It can be seen that the products in Examples 1 to 3 all formed iridium-based single-atom alloy clusters. The iridium-based single-atom alloy clusters in Example 1 had a relatively wide Ir diffraction peak feature, indicating the smaller size and weak crystallinity of the clusters; in Example 2, iridium-based single-atom alloy clusters were successfully formed, and there was no obvious vanadium metal phase, proving that the V element might be doped into the Ir lattice in the form of single atoms; the XRD half-peak width in Example 3 decreased significantly, indicating an increase in the cluster size. At the same time, it was proved that the vacuum degree could affect the cluster size. Meanwhile, there was no obvious Sn metal phase diffraction peak in the XRD, proving that the Sn element might be doped into the Ir lattice in the form of single atoms.

[0081] Example 4

[0082] The implementation method of this example was basically the same as that of Example 1, except that the rotation speed of the rotary oven was set to 100 rpm.

[0083] The iridium-based single-atom alloy cluster catalyst prepared in Example 4 was subjected to electrochemical testing, and the parameter settings were the same as those in Comparative Document 1. ICP-OES showed that the Ir content was 8.24 wt.%, and the Sn metal content was 0.98 wt.% (see Table 1 below). The catalyst prepared in this example had a relatively high apparent response current density in the mixed control region, and its mass activity reached 3658 A / g (see Table 2 below).

[0084] Example 5

[0085] The implementation method of this example was basically the same as that of Example 1, except that the temperature of the high-temperature heat treatment was set to 300 °C.

[0086] The iridium-based single-atom alloy cluster catalyst prepared in Example 5 was subjected to electrochemical testing, and the parameter settings were the same as those in Comparative Document 1. ICP-OES showed that the Ir content was 9.21 wt.%, and the Sn metal content was 3.85 wt.% (see Table 1 below).

[0087] Example 6

[0088] The implementation method of this example was basically the same as that of Example 1, except that the time of the high-temperature heat treatment was set to 20 h.

[0089] The iridium-based single-atom alloy cluster catalyst prepared in Example 6 was subjected to electrochemical testing, and the parameter settings were the same as those in Comparative Document 1. ICP-OES showed that the Ir content was 7.22 wt.%, and the Sn metal content was 4.88 wt.% (see Table 1 below). The catalyst prepared in this example had a relatively high apparent response current density in the mixed control region, and its mass activity reached 3894 A / g (see Table 2 below).

[0090] Example 7

[0091] The implementation method of this example is basically the same as that of Example 1, except that the solution used in acid etching is hydrochloric acid solution with the same concentration.

[0092] The iridium-based single-atom alloy cluster catalyst prepared in Example 7 was subjected to electrochemical testing with the same parameter settings as in Comparative Document 1. ICP-OES showed that the Ir content was 7.99 wt.%, and the Sn metal content was 2.90 wt.% (see Table 1 below).

[0093] Example 8

[0094] The implementation method of this example is basically the same as that of Example 1, except that the concentration of the H2 / Ar mixed gas is set to 20%.

[0095] The iridium-based single-atom alloy cluster catalyst prepared in Example 8 was subjected to electrochemical testing with the same parameter settings as in Comparative Document 1. ICP-OES showed that the Ir content was 11.54 wt.%, and the Sn metal content was 5.51 wt.% (see Table 1 below). The catalyst prepared in this example had a relatively high apparent response current density in the mixed control region, and its mass activity reached 3216 A / g (see Table 2 below).

[0096] Comparative Example

[0097] The implementation method of this example is basically the same as that of Example 1, except that tin acetylacetonate is not added.

[0098] The iridium-based single-atom alloy cluster catalyst prepared in the comparative example was subjected to electrochemical testing with the same parameter settings as in Comparative Document 1. ICP-OES showed that the Ir content was 10.44 wt.% (see Table 1 below).

[0099] Figure 7 Figure is the HOR polarization curve of the iridium-based single-atom alloy cluster catalysts obtained in Example 1, Example 2, Example 5, Example 7, and the comparative example at a rotation speed of 1600 rpm in 0.1 mol / L KOH saturated with hydrogen.

[0100] From Figure 7It can be seen that the apparent response current density of the catalyst prepared in Example 1 is significantly higher than that of the samples in other examples, indicating that its alkaline HOR catalytic activity is the highest; the catalyst prepared in Example 2 has a relatively high apparent response current density in the mixed control region, and its mass activity reaches 4201 A / g (see Table 2, the same below), indicating that its alkaline HOR catalytic activity has been significantly improved; the catalyst prepared in Example 5 has a relatively high apparent response current density in the mixed control region, and its mass activity reaches 3089 A / g (see Table 2, the same below); the catalyst prepared in Example 7 has a relatively high apparent response current density in the mixed control region, and its mass activity reaches 2983 A / g (see Table 2, the same below); the catalyst prepared in the comparative example has a relatively low apparent response current density in the mixed control region, and its mass activity is 768 A / g (see Table 2, the same below).

[0101] ICP-OES was used to test and analyze the Ir element and dopant metal content in the catalysts obtained in Examples 1-8 and the comparative example. The specific data are shown in Table 1.

[0102] Table 1 Ir element and dopant metal content in the catalysts obtained in Examples 1-8 and the comparative example

[0103] Case Ir element content (wt.%) Dopant metal content (wt.%) Example 1 9.87 2.71 Example 2 10.52 1.19 Example 3 7.84 1.89 Example 4 8.24 0.98 Example 5 9.21 3.85 Example 6 7.22 4.88 Example 7 7.99 2.90 Example 8 11.54 5.51 Comparative example 10.44 0

[0104] The mass activities of the iridium-based single-atom alloy cluster catalysts prepared in Examples 1-8 and the comparative example were measured. The results are shown in Table 2.

[0105] Table 2 Alkaline hydrogen oxidation catalytic mass activities of the catalysts obtained in Examples 1-8 and the comparative example

[0106] Case Mass activity (A / g) Example 1 4909 Example 2 4201 Example 3 3251 Example 4 3658 Example 5 3089 Example 6 3894 Example 7 2983 Example 8 3216 Comparative example 768

[0107] As can be seen from the above embodiments, the present invention provides a single-atom iridium-based alloy cluster catalyst, a preparation method thereof, and an electrocatalytic application, which include the following steps: Low-pressure gas-phase capillary filling: Mix an iridium organometallic precursor, a dopant organometallic precursor, a microporous carrier material, and a solvent and dry them to obtain a mixed powder. Place the mixed powder in an ampoule bottle with a certain vacuum degree and seal it, and then place it in a rotary oven for high-temperature heat treatment to obtain powder a; Temperature-controlled acid etching: Under the environment of a protective gas, mix and react powder a with an acid solution to obtain a black powder; Place the black powder in a H2 / Ar mixed gas for programmed heat treatment to obtain the single-atom iridium-based alloy cluster catalyst. Through low-pressure gas-phase capillary filling in the present invention, the iridium and the dopant organometallic precursor are sublimated and then mixed in the gas phase. The low-pressure and high-temperature environment therein induces alloying through entropy driving, which can increase the driving force of the alloying reaction, solve the thermodynamic incompatibility between multiple metals, and reduce the phase separation phenomenon between metals. The present invention utilizes the temperature-controlled acid etching technology to selectively remove the excess dopant metal elements, optimize the metal distribution on the catalyst surface, and regulate the particle size, morphology, and dispersion of the metals, which helps to improve the catalytic performance and realize the rapid, uniform, and large-scale preparation of the single-atom iridium-based alloy cluster catalyst. The single-atom iridium-based alloy cluster catalyst prepared by the method provided by the present invention shows significantly better mass activity and catalytic durability than commercial platinum-carbon in alkaline hydrogen oxidation catalysis. The mass activity can reach 4909 A / g, and it has a high apparent response current density in the mixed control region.

[0108] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a single-atom iridium-based alloy cluster catalyst, characterized in that, It includes the following steps: (1) Low-pressure gas-phase capillary filling: Mix an iridium organometallic precursor, a dopant organometallic precursor, a microporous support material, and a solvent and dry them to obtain a mixed powder. Place the mixed powder in an ampoule under a certain vacuum and seal it, and then place it in a rotary oven for high-temperature heat treatment to obtain powder a; (2) Temperature-controlled acid etching: Under the environment of a protective gas, mix and react powder a with an acid solution to obtain a black powder; place the black powder in a H2 / Ar mixed gas for programmed heat treatment to obtain the single-atom iridium-based alloy cluster catalyst.

2. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, characterized in that, In the step (1), the mass-volume ratio of the iridium organometallic precursor, the dopant organometallic precursor, the microporous support material, and the solvent is 20-60 mg: 20-60 mg: 60-100 mg: 5-15 mL.

3. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, wherein In the step (1), the dopant organometallic precursor is one or more of a tin-based organic complex, a vanadium-based organic complex, a manganese-based organic complex, a gallium-based organic complex, and an indium-based organic complex; In the step (1), the microporous support material is one or more of porous carbon, silicon carbide, metal-organic framework material, and conjugated organic framework material; In the step (1), the solvent is acetone.

4. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, wherein The vacuum degree in the step (1) is 10 -3 ~10 -5 mbar; In the step (1), the rotation speed of the rotary oven is 10-100 rpm; In the step (1), the temperature of the high-temperature heat treatment is 100-300 °C, and the time of the high-temperature heat treatment is 5-48 h.

5. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, characterized in that, In the step (2), the acid solution is one or more of a sulfuric acid solution, a hydrochloric acid solution, and a nitric acid solution; In the step (2), the concentration of the acid solution is 0.05-0.2 mol / L.

6. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, characterized in that In the step (2), the temperature of the mixed reaction is 50-90 °C, and the time of the mixed reaction is 8-12 h.

7. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, characterized in that, In the step (2), the concentration of the H2 / Ar mixed gas is 3-20%.

8. The preparation method of a single-atom iridium-based alloy cluster catalyst according to claim 1, characterized in that, In the step (2), the temperature of the programmed heat treatment is 150-200 °C, and the time of the programmed heat treatment is 1-3 h.

9. A single-atom iridium-based alloy cluster catalyst prepared by the preparation method of the single-atom iridium-based alloy cluster catalyst according to any one of claims 1-8.

10. Application of the single-atom iridium-based alloy cluster catalyst according to claim 9 as a catalyst for the hydrogen oxidation reaction at the anode of an alkaline hydrogen fuel cell.

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