A preparation method, structure and application of superfine iridium nanoparticles directly grown on a metal surface

Abstract

The application discloses a preparation method, structure and application of superfine iridium nanoparticles directly grown on a metal surface, and belongs to the technical field of catalytic materials. The method comprises the following steps: mixing two or more metal salts with a certain molar concentration, and generating a metal alloy with a sea urchin structure under the action of a reducing agent I and a surfactant; adding an iridium salt solution and a reducing agent II into the above solution and continuing to react, and finally washing the superfine iridium nanoparticles electrocatalyst directly grown on the surface of the sea urchin alloy through a water / ethanol mixed solution. The preparation method of the superfine iridium nanoparticles directly grown on the metal surface has the advantages of good iridium dispersity, high repeatability, low energy consumption, easy control and the like, and is favorable for improving the utilization rate of iridium metal. The obtained superfine iridium nanoparticles directly grown on the metal surface can be applied to an electrolytic cell.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a method, structure, and application of directly growing ultrafine iridium nanoparticles on a metal surface. Background Technology

[0002] The current energy landscape, dominated by traditional fossil fuels, cannot meet humanity's ever-growing energy demands, and the extensive use of fossil fuels causes severe damage to the ecological environment. Therefore, developing clean and efficient new energy sources is imperative. Hydrogen energy is an ideal energy source; its combustion product is water, which is environmentally friendly and holds promise as a replacement for fossil fuels. Electrolysis of water to produce hydrogen combines renewable energy with hydrogen energy, achieving zero carbon emissions throughout the entire process, making it the most ideal method for hydrogen production.

[0003] Hydrogen production via water electrolysis mainly involves two half-reactions: the oxygen evolution reaction (OER, occurring at the anode) and the hydrogen evolution reaction (HER, occurring at the cathode). Proton exchange membrane (PEM) water electrolysis offers advantages such as small footprint, fast dynamic response, wide operating range, high hydrogen purity (up to 99.99%), environmental friendliness, and the ability to operate under pressure. Currently, the anode catalysts for PEM water electrolysis primarily use iridium oxide and ruthenium oxide, with commercially available PEM electrolyzers using iridium oxide loadings of 1.5-4 mg / cm³ at the anode. 2 Or more. However, iridium resources are limited, and its high price severely hinders the large-scale application of PEM electrolyzers. Therefore, improving iridium utilization efficiency while reducing iridium metal consumption is crucial for the development of PEM electrolyzers.

[0004] Currently, there are methods that use acid-treated single-walled carbon nanotubes (SWCNTs) as a carrier to prepare IrO nanoparticles loaded on the surface of SWCNTs through calcination. x / SWCNT oxygen evolution catalyst (patent publication number CN115472852A); another method first loads Ni precursor onto polyvinylpyrrolidone modified carbon nanotubes (CNTs), and then loads Ir nanoparticles to obtain a hydrogen-oxygen fuel cell anode composite catalyst (patent publication number CN115360360A); amorphous IrO is prepared by hydrothermal method. x Nanocomposites coated with specific oxide nanomaterials, after subsequent high-temperature calcination, IrO x It is further converted into crystalline IrO2 (patent publication number CN115369422A). The above preparation method is relatively complicated, and the carbon materials or oxides used cannot withstand strong acid conditions. This invention can solve the problem of complicated preparation process in existing synthesis methods, and uses a self-made sea urchin-shaped alloy material as a carrier to disperse iridium, which reduces the amount of iridium used. At the same time, the metal alloy as a carrier can mitigate acid corrosion and extend the service life of the catalyst. Summary of the Invention

[0005] In view of the defects and shortcomings of the prior art, the purpose of this invention is to provide a method, structure and application for preparing an electrocatalyst for directly growing ultrafine iridium nanoparticles on a metal surface.

[0006] To achieve the above objectives, the preparation method adopted by the present invention comprises the following steps:

[0007] A method for preparing ultrafine iridium nanoparticles directly grown on a metal surface includes the following steps:

[0008] (1) Mix two or more metal salt aqueous solutions with a capping agent, a surfactant and a certain volume of fuming hydrochloric acid to obtain a mixed solution;

[0009] (2) After heating the mixed solution obtained in step (1) to a certain temperature, add the reducing agent I aqueous solution, heat and stir for a certain time to generate a sea urchin-shaped metal alloy;

[0010] (3) Add iridium salt aqueous solution and reducing agent II to the reaction solution in step (2), keep the temperature constant, and continue stirring for a certain period of time;

[0011] (4) Wash the mixed solution obtained in step (3) to obtain ultrafine iridium nanoparticles directly grown on the metal surface, namely, ultrafine iridium nanoparticle electrocatalysts directly grown on the surface of sea urchin-shaped alloy.

[0012] The metal salt includes palladium salt and other metal salts, wherein the other metal salt is one or more of nickel salt, copper salt, and platinum salt.

[0013] Furthermore, in the above technical solution, the molar ratio of the palladium salt to the other metal salt is 1:1 to 5:1, preferably 2:1 to 4:1.

[0014] Furthermore, in the above technical solution, when the other metal salt is one of nickel salt, copper salt, and platinum salt, the molar ratio of palladium salt to any one of the other metal salts is 1:1 to 5:1, preferably 2:1 to 4:1; when the other metal salt is two of nickel salt, copper salt, and platinum salt, the molar ratio of palladium salt to the sum of the two other metal salts is 1:1 to 5:1, preferably 2:1 to 4:1, and the molar ratio of any two of the other metal salts is 1:1 to 4:1, preferably 1:1 to 3:1; when the other metal salt is three of nickel salt, copper salt, and platinum salt, the molar ratio of palladium salt to the sum of the three metal salts is 1:1 to 5:1, preferably 2:1 to 4:1, and the molar ratio of platinum salt, copper salt, and nickel salt is 1:1:1 to 3:1:1, preferably 1:1:1 to 2:1:1.

[0015] Furthermore, in the above technical solution, the nickel salt includes one of NiCl2·6H2O, Ni(H2PO2)2·6H2O, and NiN2O6·6H2O;

[0016] The copper salt includes one of the following: C6H4Cu2O7·2.5H2O, C4H6CuO4, C6H8Cu2O7, CuC2O4, CuCl2·2H2O, CuCl2, Cu(NO3)2·6H2O, Cu(NO3)2·3H2O, CuSO4·5H2O, and CuSO4;

[0017] The platinum salt includes one of H2PtCl6·6H2O, K2PtCl6, K2PtCl4, PtCl2, PtCl4, sodium tetrachloroplatinate(II) hydrate, hexachloroplatinate(IV) hydrate, N2H8PtCl6, H8Cl4N2Pt, and Cl6Na2Pt.

[0018] The palladium salts include PdCl2, K2PdCl4, PdSO4, C4H6O4Pd, Pd(NO3)2, PdN2H6Cl2, Cl4Na2Pd, and Cl2H 12 One of N4Pd, H8Cl6N2Pd, and H8Cl4N2Pd;

[0019] The iridium salt includes C 12 H 18 Ir3O 15 One of the following: C2H3O2.3H2O, IrCl3, Na2IrCl6·6H2O, K3IrCl6, K2IrCl6, Na2IrCl6, (NH4)2IrCl6, iridium(IV) hydrate, iridium(III) hydrate, sodium hexachloroiridium(III) hydrate, and hexachloroiridium(III) acid hydrate;

[0020] The capping agent is KI or KBr;

[0021] The surfactant is one of polyvinylpyrrolidone, a copolymer of propylene oxide and ethylene oxide F127, a triblock copolymer P123, and hexadecyltrimethylammonium bromide;

[0022] The reducing agent I is one of citric acid, sodium citrate, ascorbic acid, sodium ascorbate, glucose, and sodium gluconate;

[0023] The reducing agent II is formic acid or acetic acid.

[0024] Furthermore, in the above technical solution, the molar concentration of the metal salt aqueous solution in step (1) is 1 to 500 mM, preferably 10 to 100 mM, and more preferably 20 to 80 mM.

[0025] Furthermore, in the above technical solution, the molar concentration of the capping agent in step (1) in the mixed solution is 0.01 to 0.2 mM, preferably 0.06 to 0.15 mM.

[0026] Furthermore, in the above technical solution, the molar concentration of the surfactant in the mixed solution in step (1) is 0.001 to 0.05 mM, preferably 0.01 to 0.03 mM.

[0027] Furthermore, in the above technical solution, the volume ratio of the metal salt solution to the fuming hydrochloric acid in step (1) is 15 to 50:1, preferably 25 to 40:1.

[0028] Furthermore, in the above technical solution, the temperature in step (2) is 90-130℃, preferably 90-110℃.

[0029] Furthermore, in the above technical solution, the molar ratio of reducing agent I to the metal salt in step (2) is 10:1 to 1:1, preferably 8:1 to 2:1; the molar concentration of the aqueous solution of reducing agent I is 40 to 120 mM, preferably 80 to 110 mM.

[0030] Furthermore, in the above technical solution, the heating and stirring time in step (2) is 0.5 to 5 hours, preferably 1 to 3 hours.

[0031] Furthermore, in the above technical solution, the molar ratio of iridium salt to metal salt in step (3) is 2:1 to 1:30, preferably 1:2 to 1:4; the molar concentration of the iridium salt aqueous solution is 1 to 200 mM, preferably 5 to 60 mM, and more preferably 10 to 40 mM.

[0032] Furthermore, in the above technical solution, the volume ratio of reducing agent II to iridium salt solution in step (3) is 1:1 to 5:1, preferably 1:1 to 3:1.

[0033] Furthermore, in the above technical solution, the heating and stirring time in step (3) is 0.5 to 5 hours, preferably 1 to 3 hours.

[0034] Furthermore, in the above technical solution, the washing in step (4) is washing with a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol in the mixed solution is 3:1 to 1:1, preferably 1.5:1 to 1:1.

[0035] Furthermore, in the above technical solution, the particle size of the ultrafine iridium metal nanoparticles directly grown on the surface of the metal carrier is less than 5 nm.

[0036] This invention provides a method for directly growing ultrafine iridium nanoparticles on a metal surface using the above-described preparation method.

[0037] The present invention also provides the application of the aforementioned direct growth of ultrafine iridium nanoparticles on metal surfaces in electrolytic cells.

[0038] The electrocatalyst for directly growing ultrafine iridium nanoparticles on metal surfaces prepared by this invention has the advantages of simple preparation process, low energy consumption, low preparation cost, strong universality of preparation method, and flexible and controllable preparation process. The ultrafine iridium nanoparticles directly grown on metal surfaces prepared by the preferred conditions of this invention have excellent HER activity and stability, OER activity and stability, and PEM water electrolysis single cell performance under low loading.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) The preparation process of the electrocatalyst for direct growth of ultrafine iridium nanoparticles on metal surface provided by the present invention is simple, highly reproducible, energy-efficient and easy to control.

[0041] (2) The electrocatalyst for direct growth of ultrafine iridium nanoparticles on metal surface provided by the present invention has iridium nanoparticles grown directly and uniformly on the surface of metal support. Iridium has good dispersion and high utilization rate. At the same time, the interaction between iridium and support is strong, which can alleviate acid corrosion problem and improve the service life of catalyst.

[0042] (3) The PEM water electrocatalyst for direct growth of ultrafine iridium nanoparticles on a metal surface provided by this invention exhibits excellent OER and HER activity and durability in a 0.5 mol / L H2SO4 electrolyte. At 10 mA / cm², 2 At current densities of 15 and 300 μg, the loading is... Ir / cm 2 The overpotentials of the OER were 290 and 191 mV, respectively; at 10 mA / cm 2 Chronopotential (CP) testing was performed at a current density of 10 mA / cm² for 20 hours, and the potential remained basically stable. 2 At a current density of 15 μg, the overpotential of HER is only 9 mV (with a loading of 15 μg). Ir / cm 2 ); Under accelerated aging test (ADT) with a voltage range of 0.1V to -0.1V for 10,000 cycles, no performance degradation was observed; at 0.3mg Ir cm -2The loading capacity was used to fabricate the anode membrane electrode assembly for PEM water electrolysis single-cell testing at 1A cm⁻¹. -2 The voltage is 1.69V. Attached Figure Description

[0043] Figure 1 Transmission electron microscope image of the urchin-shaped PdCu alloy prepared in Example 1: scale bar 100 nm.

[0044] Figure 2 Transmission electron microscope image of the urchin-shaped PdCu alloy prepared in Example 2: scale bar 100 nm.

[0045] Figure 3 Transmission electron microscope image of the urchin-shaped PdCu alloy prepared in Example 3: scale bar 100 nm.

[0046] Figure 4 Transmission electron microscope image of the urchin-shaped PtPdCuNi alloy prepared in Example 4: scale bar 100 nm.

[0047] Figure 5 Transmission electron microscope image of the urchin-shaped PdCuNi alloy prepared in Example 5: scale bar 100 nm.

[0048] Figure 6 Scanning electron microscope image of the urchin-like PdCu alloy prepared in Example 3: scale bar 400 nm.

[0049] Figure 7 Scanning electron microscope image of the Ir / PdCu catalyst prepared in Example 3: scale bar 400 nm.

[0050] Figure 8 Transmission electron microscopy images (scale bar 100 nm) of the Ir / PdCu catalysts prepared for Examples 1, 2, 3, 8 and 9: (a) 1 mL 10 mmol IrCl3 (Example 1); (b) 2 mL 20 mmol Na2IrCl6·6H2O (Example 2); (c) 3 mL 30 mmol K2IrCl6 (Example 3); (d) 4 mL 40 mmol IrCl3 (Example 8); (e) 5 mL 50 mmol K3IrCl6 (Example 9).

[0051] Figure 9 Transmission electron micrographs (scale bar 100 nm) of the Ir / PdCu catalysts prepared for Examples 10, 11 and 12: (a) 1 h (Example 10); (b) 2 h (Example 11); (c) 4 h (Example 12).

[0052] Figure 10Transmission electron microscope image of the catalyst prepared for Comparative Example 1: scale bar 100 nm.

[0053] Figure 11 Transmission electron microscope image of the catalyst prepared for Comparative Example 2: scale bar 500 nm.

[0054] Figure 12 Transmission electron microscope image of the catalyst prepared for Comparative Example 3: scale bar 100 nm.

[0055] Figure 13 Inductively coupled plasma atomic emission spectrometry (ICP-OES) data of the Ir / PdCu catalysts prepared in Examples 1, 2, 3, 8 and 9.

[0056] Figure 14 The urchin-like PdCu alloy prepared in Example 3, and the Ir alloy prepared in Examples 1, 2, 3, 8, and 9. 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 X-ray powder diffraction pattern of Cu catalyst.

[0057] Figure 15 High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) images of the sea urchin-like Ir / PdCu catalyst prepared in Example 3: (a) scale bar 5 nm, (b) scale bar 2 nm.

[0058] Figure 16 Ir prepared in Example 3 0.58 / Pd 1.9 Cu and commercial Ir black catalyst at different scan rates (20 mV s) -1 40mV s -1 60mV s -1 80mV s -1 100mV s -1 120mV s -1 140mV s -1 160mVs -1 Cyclic voltammetry (CV) curves under )

[0059] Figure 17 Ir prepared in Example 30.58 / Pd 1.9 Current density versus scan rate (20 mV s) of Cu and commercial Ir black catalyst at 0.35 V (vs. RHE) -1 40mV s -1 60mV s -1 80mV s -1 100mV s -1 120mVs -1 140mV s -1 160mV s -1 A linear relationship diagram was drawn.

[0060] Figure 18 Ir prepared for Examples 1, 2, 3, 8 and 9 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Polarization curves (LSV) of Cu catalyst (a), at 10 mA cm⁻¹ -2 The overpotential diagram below (b).

[0061] Figure 19 Ir prepared for Examples 1, 2, 3, 8 and 9 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Tafel curve of Cu catalyst.

[0062] Figure 20 Oxygen evolution polarization (LSV) curves (a) and Tafel curves (b) for commercial Ir black catalysts.

[0063] Figure 21 Ir prepared in Example 3 0.58 / Pd 1.9 Cu catalyst and commercial Ir black were used with increased loading of 300 μg. Ir / cm 2 The oxygen evolution polarization curve (LSV) diagram (a) and the Tafel curve diagram (b) are shown.

[0064] Figure 22 Ir prepared in Example 3 0.58 / Pd 1.9 Chronopotential (CP) curves of Cu catalyst and commercial Ir black.

[0065] Figure 23 Ir prepared in Example 3 0.58 / Pd 1.9 Hydrogen evolution polarization curves of Cu catalyst and commercial 20 wt% Pt / C catalyst (a) and Ir prepared in Example 3 0.58 / Pd 1.9 Figure (b) shows the hydrogen evolution polarization curves of the Cu catalyst before and after 10,000 accelerated aging tests.

[0066] Figure 24 Ir prepared in Example 3 0.58 / Pd 1.9 Performance diagram of single-cell water electrolysis using Cu catalyst and commercial Ir black. Detailed Implementation

[0067] The specific implementation of the present invention will be further described below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0068] Example 1

[0069] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0070] (1) Mix 2 mL of 80 mM KPdCl4, 3 mL of 20 mM CuCl2, 0.15 mL of fuming hydrochloric acid, 0.6 mmol of KBr and 0.05 mmol of polyvinylpyrrolidone evenly, stir and heat the mixture to 90 °C, add 5 mL of 80 mM citric acid and keep for 1 h to obtain sea urchin-shaped PdCu alloy.

[0071] (2) 1 mL of 10 mM IrCl3 and 1 mL of formic acid (the volume ratio of formic acid to iridium salt solution is 1:1) were added to the solution obtained in step (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 1 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 2:1) and dried to obtain the Ir / PdCu catalyst.

[0072] Example 2

[0073] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0074] (1) Mix 4 mL of 40 mM KPdCl4, 1 mL of 60 mM CuCl2, 0.2 mL of fuming hydrochloric acid, 0.5 mmol of KI and 0.08 mmol of F127, a copolymer of propylene oxide and ethylene oxide, evenly, stir and heat the mixture to 100 °C, add 4 mL of 90 mM ascorbic acid and maintain for 4 h to obtain a sea urchin-shaped PdCu alloy;

[0075] (2) 2 mL of 20 mM Na2IrCl6·6H2O and 3 mL of formic acid (the volume ratio of formic acid to iridium salt solution is 1.5:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 2 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1.5:1) and dried to obtain the Ir / PdCu catalyst.

[0076] Example 3

[0077] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0078] (1) Mix 8 mL of 20 mM KPdCl4, 2 mL of 30 mM CuCl2, 0.3 mL of fuming hydrochloric acid, 1 mmol of KBr and 0.25 mmol of triblock copolymer P123 evenly, stir and heat the mixture to 100 °C, add 10 mL of 100 mM glucose and keep for 4 h to obtain sea urchin-shaped PdCu alloy;

[0079] (2) 3 mL of 30 mM K2IrCl6 and 6 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 3 h. After cooling, the solution was washed with a mixture of deionized water and ethanol (volume ratio 1:1) and dried to obtain the Ir / PdCu catalyst.

[0080] Example 4

[0081] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0082] (1) Mix 2 mL of 20 mM KPtCl4, 6 mL of 40 mM KPdCl4, 1 mL of 20 mM CuCl2, 1 mL of 20 mM NiCl2, 0.4 mL of fuming hydrochloric acid, 1.6 mmol of KI and 0.2 mmol of cetyltrimethylammonium bromide evenly, stir and heat the mixture to 120 °C, add 7 mL of 110 mM sodium citrate and maintain for 5 h to obtain sea urchin-shaped PtPdCuNi alloy;

[0083] (2) 3 mL of 30 mM (NH4)2IrCl6 and 6 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 2 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1.5:1) and dried to obtain the Ir / PtPdCuNi catalyst.

[0084] Example 5

[0085] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0086] (1) Mix 10 mL of 30 mM KPdCl4, 2 mL of 30 mM Cu(NO3)2·3H2O, 2 mL of 10 mM Ni(NO3)2·6H2O, 0.5 mL of fuming hydrochloric acid, 1.8 mmol of KI and 0.3 mmol of polyvinylpyrrolidone evenly, stir and heat the mixture to 130 °C, add 9 mL of 80 mM sodium ascorbate and keep for 3 h to obtain sea urchin-shaped PdCuNi alloy;

[0087] (2) 5 mL of 10 mM K3IrCl6 and 5 mL of formic acid (the volume ratio of formic acid to iridium salt solution is 1:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 5 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 2:1) and dried to obtain the Ir / PdCuNi catalyst.

[0088] Example 6

[0089] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0090] (1) Mix 8 mL of 20 mM KPdCl4, 3 mL of 10 mM Cu(NO3)2·3H2O, 4 mL of 10 mM Ni(NO3)2·6H2O, 0.5 mL of fuming hydrochloric acid, 2 mmol of KBr and 0.2 mmol of F127, a copolymer of propylene oxide and ethylene oxide, until homogeneous. Stir and heat the mixture to 90 °C, add 10 mL of 110 mM sodium gluconate and maintain for 2 h to obtain a sea urchin-shaped PdCuNi alloy.

[0091] (2) 4 mL of 40 mM H2IrCl6·6H2O and 10 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2.5:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 4 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1:1) and dried to obtain the Ir / PdCuNi catalyst.

[0092] Example 7

[0093] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0094] (1) Mix 4 mL of 20 mM KPdCl4, 1.5 mL of 20 mM CuCl2, 0.2 mL of fuming hydrochloric acid, 0.5 mmol of KI and 0.07 mmol of triblock copolymer P123 evenly, stir and heat the mixture to 120 °C, add 5 mL of 60 mM sodium gluconate and keep for 4 h to obtain sea urchin-shaped PdCu alloy;

[0095] (2) 1 mL of 50 mM H2IrCl6·6H2O and 3 mL of formic acid (the volume ratio of formic acid to iridium salt solution is 3:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the mixture was heated and stirred for 5 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1.5:1) and dried to obtain the Ir / PdCu catalyst.

[0096] Example 8

[0097] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0098] (1) Mix 4 mL of 40 mM KPdCl4, 3 mL of 20 mM CuCl2, 0.2 mL of fuming hydrochloric acid, 0.6 mmol of KBr and 0.12 mmol of cetyltrimethylammonium bromide evenly, stir and heat the mixture to 100 °C, add 9 mL of 50 mM citric acid and keep for 3 h to obtain sea urchin-shaped PdCu alloy;

[0099] (2) 4 mL of 40 mM IrCl3 and 10 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2.5:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 2 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1:1) and dried to obtain the Ir / PdCu catalyst.

[0100] Example 9

[0101] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0102] (1) Mix 2 mL of 80 mM KPdCl4, 2 mL of 30 mM CuCl2, 0.1 mL of fuming hydrochloric acid, 0.4 mmol of KBr and 0.1 mmol of polyvinylpyrrolidone evenly, stir and heat the mixture to 90 °C, add 6 mL of 100 mM ascorbic acid and keep it for 1 h to obtain sea urchin-shaped PdCu alloy.

[0103] (2) 5 mL of 50 mM K3IrCl6 and 15 mL of formic acid (the volume ratio of formic acid to iridium salt solution is 3:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 3 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1.5:1) and dried to obtain the Ir / PdCu catalyst.

[0104] Example 10

[0105] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0106] (1) Mix 8 mL of 20 mM KPdCl4, 1 mL of 60 mM CuCl2, 0.3 mL of fuming hydrochloric acid, 0.8 mmol of KBr and 0.15 mmol of F127, a copolymer of propylene oxide and ethylene oxide, evenly, stir and heat the mixture to 100 °C, add 7 mL of 80 mM sodium citrate and keep for 2 h to obtain a sea urchin-shaped PdCu alloy;

[0107] (2) 3 mL of 30 mM IrCl3 and 6 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 1 h. After cooling, the solution was washed with a water / ethanol (volume ratio 1:1) mixture and dried to obtain the Ir / PdCu catalyst.

[0108] Example 11

[0109] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0110] (1) Mix 2 mL of 80 mM KPdCl4, 1 mL of 60 mM CuCl2, 0.1 mL of fuming hydrochloric acid, 0.3 mmol of KI and 0.09 mmol of triblock copolymer P123 evenly, stir and heat the mixture to 100 °C, add 8 mL of 110 mM sodium gluconate and keep for 1 h to obtain sea urchin-shaped PdCu alloy;

[0111] (2) 3 mL of 30 mM K3IrCl6 and 6 mL of formic acid (the ratio of formic acid to iridium salt solution is 2:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the mixture was heated and stirred for 2 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1.5:1) and dried to obtain the Ir / PdCu catalyst.

[0112] Example 12

[0113] A method for preparing an electrocatalyst that directly grows ultrafine iridium nanoparticles on a metal surface, comprising the following steps:

[0114] (1) Mix 4 mL of 40 mM KPdCl4, 2 mL of 30 mM CuCl2, 0.2 mL of fuming hydrochloric acid, 0.6 mmol of KBr and 0.06 mmol of cetyltrimethylammonium bromide evenly, stir and heat the mixture to 100 °C, add 9 mL of 100 mM mmol of ascorbic acid and keep for 3 h to obtain sea urchin-shaped PdCu alloy;

[0115] (2) 3 mL of 30 mM Na2IrCl6 and 6 mL of acetic acid (the volume ratio of acetic acid to iridium salt solution is 2:1) were added to the solution obtained in (1) in sequence. The temperature was kept constant, and the solution was heated and stirred for 4 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1:1) and dried to obtain the Ir / PdCu catalyst.

[0116] Comparative Example 1

[0117] The catalyst is prepared by changing the reaction temperature, and the steps are as follows:

[0118] (1) Mix 2 mL of 80 mM KPdCl4, 3 mL of 20 mM CuCl2, 0.15 mL of fuming hydrochloric acid, 0.6 mmol of KBr and 0.05 mmol of polyvinylpyrrolidone evenly, stir and heat the mixture to 140 °C, add 5 mL of 80 mM citric acid and keep for 1 h to obtain sea urchin-shaped PdCu alloy.

[0119] (2) After cooling, the catalyst was washed with a mixture of deionized water and ethanol (volume ratio 2:1) and dried to obtain the catalyst of Comparative Example 1.

[0120] Comparative Example 2

[0121] The catalyst is prepared without the addition of a surfactant, and the steps are as follows:

[0122] (1) Mix 8 mL of 20 mM KPdCl4, 2 mL of 30 mM CuCl2, 0.3 mL of fuming hydrochloric acid and 1 mmol KBr evenly, stir and heat the mixture to 100 °C, add 10 mL of 100 mM glucose and keep it for 4 h;

[0123] (2) After cooling, the catalyst was washed with a mixture of deionized water and ethanol (volume ratio 1:1) and dried to obtain the catalyst of Comparative Example 2.

[0124] Comparative Example 3

[0125] The catalyst is prepared by replacing formic acid or acetic acid with sodium borohydride, and the steps are as follows:

[0126] (1) Mix 8 mL of 20 mM KPdCl4, 2 mL of 30 mM CuCl2, 0.3 mL of fuming hydrochloric acid, 1 mmol of KBr and 0.25 mmol of triblock copolymer P123 evenly, stir and heat the mixture to 100 °C, add 10 mL of 100 mM glucose and keep for 4 h to obtain sea urchin-shaped PdCu alloy;

[0127] (2) 3 mL of 30 mM K2IrCl6 and 6 mL of 30 mM sodium borohydride aqueous solution (volume ratio of 2:1 to iridium salt solution) were added sequentially to the solution obtained in step (1). The temperature was kept constant, and the solution was heated and stirred for 3 h. After cooling, the solution was washed with a mixture of deionized water / ethanol (volume ratio 1:1) and dried to obtain the catalyst of Comparative Example 3.

[0128] Application Example 1: Catalyst Structure Characterization

[0129] Figure 1 Transmission electron microscope image of the urchin-like PdCu alloy prepared in Example 1. Figure 1 It can be observed that the PdCu alloy prepared in Example 1 has a sea urchin-like morphology.

[0130] Figure 2 Transmission electron microscope image of the urchin-like PdCu alloy prepared in Example 2. Figure 2 It can be observed that the PdCu alloy prepared in Example 2 has a sea urchin-like morphology.

[0131] Figure 3 Transmission electron microscope image of the urchin-like PdCu alloy prepared in Example 3. Figure 3 It can be observed that the PdCu alloy prepared in Example 3 has a sea urchin-like morphology.

[0132] Figure 4This is a transmission electron microscope image of the urchin-like PtPdCuNi alloy prepared in Example 4. Figure 4 It can be observed that the PtPdCuNi alloy prepared in Example 4 has a sea urchin-like morphology.

[0133] Figure 5 Transmission electron microscope image of the urchin-like PdCuNi alloy prepared in Example 5. Figure 5 It can be observed that the PdCuNi alloy prepared in Example 5 has a sea urchin-like morphology.

[0134] Figure 6 The image shows a scanning electron microscope (SEM) image of the sea urchin-like PdCu alloy prepared in Example 3. The SEM results show that the PdCu alloy prepared in Example 3 has a sea urchin-like morphology.

[0135] Figure 7 The image shows a scanning electron microscope (SEM) image of the Ir / PdCu catalyst prepared in Example 3. The SEM results show that the Ir / PdCu prepared in Example 3 retains the urchin-like morphology of PdCu, with iridium nanoparticles uniformly grown on the PdCu surface.

[0136] Figure 8 Transmission electron microscope images of the Ir / PdCu catalysts prepared in Examples 1, 2, 3, 8 and 9. Figure 8 (a) is the Ir / PdCu catalyst obtained in Example 1 with the addition of 1 mL of 10 mM iridium salt; Figure 8 (b) is the Ir / PdCu catalyst obtained in Example 2 with the addition of 2 mL of 20 mM iridium salt; Figure 8 (c) is the Ir / PdCu catalyst obtained in Example 3 with the addition of 3 mL of 30 mM iridium salt; Figure 8 (d) is the Ir / PdCu catalyst obtained in Example 8 with the addition of 4 mL of 40 mM iridium salt; Figure 8 (e) is the Ir / PdCu catalyst obtained in Example 9 with the addition of 5 mL of 50 mM iridium salt. Figure 8 It is observed that as the amount of iridium salt increases, more and more Ir nanoparticles are grown on PdCu. When using 3 mL of 30 mM iridium salt, the Ir nanoparticles grow uniformly on the PdCu surface. Further increasing the amount of iridium salt causes the Ir nanoparticles on the PdCu surface to agglomerate, which is detrimental to iridium dispersion and reduces iridium utilization. Therefore, using 3 mL of 30 mM iridium salt yields the catalyst with the best iridium dispersion.

[0137] Figure 9 Transmission electron microscopy images of the Ir / PdCu catalysts prepared in Examples 10, 11 and 12. Figure 9(a) is the Ir / PdCu catalyst obtained in Example 10 with a reaction time of 1 h; Figure 9 (b) is the Ir / PdCu catalyst obtained in Example 11 with a reaction time of 2 h; Figure 9 (c) is the Ir / PdCu catalyst obtained in Example 12 with a reaction time of 4 h. The Ir / PdCu catalysts prepared in Examples 10, 11 and 12 were obtained at different reaction times. Combined with the transmission electron microscopy results of the Ir / PdCu catalyst prepared in Example 3, it can be seen that as the reaction time increases, the Ir nanoparticles on the PdCu surface first increase and then agglomerate. When the reaction time is 3 h, the iridium nanoparticles grow uniformly on the PdCu surface, and the dispersion is the best.

[0138] Figure 10 Transmission electron microscope image of the catalyst prepared for Comparative Example 1. Figure 10 It can be seen that changing the reaction temperature results in an irregular elongated structure rather than a sea urchin morphology, indicating that the reaction temperature has a significant impact on the formation of sea urchin morphology.

[0139] Figure 11 Transmission electron microscopy (TEM) image of the catalyst prepared for Comparative Example 2. Surfactants play a role in morphology regulation of nanomaterials. Without surfactants, irregular morphologies were obtained, indicating that surfactants have a unique and indispensable role in the formation of sea urchin morphology.

[0140] Figure 12 Transmission electron microscopy image of the catalyst prepared for Comparative Example 3. Formic acid or acetic acid plays an important guiding role in the growth of iridium nanoparticles on the surface of the sea urchin alloy, and also acts as a reducing agent for iridium salts. Figure 12 It is known that when sodium borohydride is used instead of formic acid or acetic acid in the reaction, sodium borohydride can only play a reducing role, reducing iridium salt to iridium nanoparticles, but cannot make it grow on the alloy surface.

[0141] Figure 13 Inductively coupled plasma atomic emission spectrometry (ICP-OES) data of the Ir / PdCu catalysts prepared in Examples 1, 2, 3, 8 and 9. Figure 13 (a) ICP-OES data of the Ir / PdCu catalyst prepared in Example 1; Figure 13 (b) ICP-OES data of the Ir / PdCu catalyst prepared in Example 2; Figure 13 (c) ICP-OES data of the Ir / PdCu catalyst prepared in Example 3; Figure 13 (d) ICP-OES data of the Ir / PdCu catalyst prepared in Example 8; Figure 13(e) ICP-OES data for the Ir / PdCu catalyst prepared in Example 9. Figure 13 It can be seen that the chemical compositions of the Ir / PdCu catalysts prepared in Examples 1, 2, 3, 8, and 9 are as follows: Ir 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Analysis of ICP-OES data shows that the increase in Ir content is accompanied by a decrease in Pd content, while the Cu content remains almost unchanged. This indicates that under the influence of formic acid or acetic acid, Ir... 3+ Ir undergoes a displacement reaction with Pd in ​​PdCu, thereby achieving the growth of Ir on the PdCu surface.

[0142] Figure 14 The urchin-like PdCu alloy prepared in Example 3, and the Ir alloy prepared in Examples 1, 2, 3, 8, and 9. 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 X-ray powder diffraction pattern of Cu catalyst. The chemical composition of the urchin-like PdCu alloy prepared in Example 3 was determined to be Pd using ICP-OES. 2.8 Cu. From Figure 14 It can be seen that Pd 2.8 The diffraction peaks of Cu match those of the PDF card Ir-PDF#46-1044, indicating that Pd 2.8 The lattice matching between Cu and Ir facilitates the growth of iridium nanoparticles on the PdCu surface. 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Cu diffraction peaks and Pd 2.8The uniformity of Cu further demonstrates that this lattice matching is beneficial to the growth of iridium nanoparticles on the PdCu surface.

[0143] Figure 15 This is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of the urchin-like Ir / PdCu catalyst prepared in Example 3. Figure 15 (a) It can be seen that ultrafine Ir nanoparticles of 1-2 nm are uniformly distributed on the PdCu surface; from Figure 15 (b) It can be seen that the interplanar spacing of Ir nanoparticles corresponds to 0.22 nm for Ir(111)(Ir-PDF#46-1044), which is consistent with the lattice spacing of PdCu, indicating that there is a perfect lattice match between Ir and PdCu, which is consistent with the XRD characterization results.

[0144] Application Example 2: Catalyst Performance Testing

[0145] Ir prepared in Examples 1, 2, 3, 8 and 9 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Cu catalyst was used in the PEM water electrolysis reaction under the following conditions: temperature 25℃. 3 mg of catalyst was weighed and added to 300 μL of ultrapure water, 2700 μL of ethanol, and 18 μL of Nafion solution (5 wt%). The mixture was sonicated to form a homogeneous mixture. 10 μL of this mixture was dropped onto a 5 mm diameter glassy carbon electrode to prepare the working electrode. The catalyst loading was 51 μg. catalyst / cm 2 (15μg Ir / cm 2A three-electrode system was constructed using a mercury / mercurous sulfate electrode (reference electrode), a graphite rod (counter electrode), and a glassy carbon electrode coated with the catalyst (working electrode). 0.5 mol / L H₂SO₄ was used as the electrolyte. The catalytic performance of the catalyst was assessed using a CHI760E electrochemical workstation, including cyclic voltammetry (CV) curves, linear polarization (LSV) curves and corresponding Tafel plots, as well as chronopotential (CP) test curves. The test conditions were as follows: activation CV scan range: 0–1.2 V (vs RHE), scan rates: 50 and 100 mV / s; double-layer CV scan range: 0.89–0.99 V (vs RHE), scan rate: 20–160 mV / s; LSV scan rate: 10 mV / s; working electrode rotation speed: 1600 rpm; CP testing was performed at a current density of 10 mA / cm². 2 The following tests were performed: ADT CV scan range was 0.1V–0.1V (vs RHE), and scan rate was 100 mV / s. OER testing used commercial Ir black as the control working electrode, purchased from Shanghai Hesen Electric Co., Ltd. HER testing used a commercial 20wt% Pt / C catalyst as the control working electrode, purchased from Johnson Matthey.

[0146] Figure 16 Ir prepared in Example 3 0.58 / Pd 1.9 Cu and commercial Ir black catalyst at different scan rates (20 mV s) -1 40mV s -1 60mV s -1 80mV s -1 100mV s -1 120mV s -1 140mV s -1 160mVs -1 The CV curve is shown below. As the scan speed increases, the current density of the CV curve also increases.

[0147] Figure 17 Ir prepared in Example 3 0.58 / Pd 1.9 Current density versus scan rate (20 mV s) of Cu and commercial Ir black catalyst at 0.35 V (vs RHE) -1 40mV s -1 60mV s -1 80mV s-1 100mV s -1 120mVs -1 140mV s -1 160mV s -1 A linear relationship graph was drawn. Figure 17 It is known that the Ir prepared in Example 3 0.58 / Pd 1.9 Cu and C of commercial Ir black catalyst dl The values ​​were 8.92 and 4.32 mF cm, respectively. -2 The electrochemical specific surface area (ECSA) of a catalyst is calculated using the double-layer method: ECSA = C dl / C s C s The value is 0.035mF cm. -2 Ir prepared in Example 3 0.58 / Pd 1.9 The ECSA of the Cu catalyst is 850.6 m. 2 g -1 It is a commercial Ir black catalyst (411.9m). 2 g -1 Twice as much as 1.

[0148] Figure 18 Ir prepared for Examples 1, 2, 3, 8 and 9 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Oxygen evolution polarization (LSV) curves of Cu catalyst (a), at 10 mA cm⁻¹ -2 The overpotential diagram below (b). According to... Figure 18 (a) LSV curve, at a current density of 10 mA / cm² 2 Below, the overpotential η = (E - 1.23) * 1000mV can be calculated to obtain Ir. 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir0.85 / Pd 1.7 The η values ​​for Cu are 367mV, 305mV, 290mV, 295mV, and 318mV, respectively. The theoretical evolution potential of oxygen is 1.23V (vs. RHE). In actual electrode reactions, the anode potential is higher than the theoretical value; this is called overpotential. The smaller the overpotential, the better the catalytic performance of the catalyst. Figure 18 (a) and (b) indicate that Ir 0.58 / Pd 1.9 Cu catalysts have the lowest overpotential and exhibit the best catalytic activity.

[0149] Figure 19 Ir prepared for Examples 1, 2, 3, 8 and 9 0.15 / Pd 2.4 Cu, Ir 0.44 / Pd 2.1 Cu, Ir 0.58 / Pd 1.9 Cu, Ir 0.73 / Pd 1.8 Cu and Ir 0.85 / Pd 1.7 Tafel curves for Cu catalysts. Tafel curves are commonly used to analyze and evaluate the performance of catalysts in OER reactions. A smaller Tafel slope indicates faster reaction kinetics and a faster catalytic kinetics in the OER reaction. Figure 19 It can be seen that Ir 0.58 / Pd 1.9 Cu catalysts exhibit the fastest catalytic reaction kinetics.

[0150] Figure 20 (a) Oxygen evolution polarization (LSV) curves of a commercial Ir black catalyst at a current density of 10 mA / cm². 2 Below, the calculated overpotential η of commercial Ir black is 348 mV, which is higher than that of Ir prepared in Example 3. 0.58 / Pd 1.9 Cu catalyst (290 mV) indicates Ir 0.58 / Pd 1.9 The Cu catalyst exhibits superior catalytic activity compared to commercial Irblack. Figure (b) shows the Tafel curve of the commercial Irblack catalyst, with a Tafel slope of 84.5 mV dec. -1 It is also higher than Ir 0.58 / Pd 1.9 Cu catalyst (49.5mV dec) -1 This proves that Ir0.58 / Pd 1.9 Cu catalysts exhibit faster catalytic reaction kinetics.

[0151] Figure 21 (a) Ir prepared in Example 3 0.58 / Pd 1.9 Cu catalyst and commercial Ir black were used with increased loading of 300 μg. Ir / cm 2 Oxygen evolution polarization curve (LSV) plot at time Ir 0.58 / Pd 1.9 The overpotential η of the Cu catalyst is 191 mV, which is 71 mV lower than that of the commercial Ir black catalyst, further demonstrating the effectiveness of Ir catalysts. 0.58 / Pd 1.9 The Cu catalyst exhibits superior catalytic activity compared to commercial Ir black. Figure (b) shows the Ir prepared in Example 3. 0.58 / Pd 1.9 Tafel curves for Cu catalysts and commercial Ir black catalysts, Ir 0.58 / Pd 1.9 The Tafel slope of the Cu catalyst is 52.4 mV dec. -1 Lower than commercial Ir black (119.5mV dec) -1 This proves once again that Ir 0.58 / Pd 1.9 Cu catalysts exhibit faster catalytic reaction kinetics than commercial Ir black catalysts.

[0152] Figure 22 Ir prepared in Example 3 0.58 / Pd 1.9 Chronopotential (CP) curves of Cu catalyst and commercial Ir black. At a current density of 10 mA / cm². 2 Under these conditions, the potential changes over time. Figure 22 It can be seen that when the test was conducted for approximately 9 hours, the potential of commercial Ir black rose sharply and then remained essentially constant, indicating that commercial Ir black had been deactivated and lost its catalytic performance. However, Ir... 0.58 / Pd 1.9 After 20 hours of testing, the potential of Cu remained relatively stable, and the CP test results showed that Ir 0.58 / Pd 1.9Cu catalysts exhibit excellent OER catalytic stability.

[0153] Figure 23 (a) Ir prepared in Example 3 0.58 / Pd 1.9 Hydrogen evolution polarization curves of Cu catalyst and commercial 20wt% Pt / C catalyst, Ir 0.58 / Pd 1.9 Cu catalyst at 10 mA / cm 2 The overpotential under Ir is only 9 mV, lower than that of a commercial 20 wt% Pt / C catalyst (12 mV), indicating that Ir 0.58 / Pd 1.9 The Cu catalyst exhibits superior HER catalytic activity compared to the commercial 20 wt% Pt / C catalyst. Figure (b) shows the Ir prepared in Example 3. 0.58 / Pd 1.9 Hydrogen evolution polarization curves of Cu catalyst before and after 10,000 cycles of ADT testing. Figure 23 (b) It can be seen that before and after the ADT test, Ir 0.58 / Pd 1.9 Cu catalyst at a current density of 10 mA / cm 2 The overpotentials under all conditions were 9mV, with no decay, indicating that Ir 0.58 / Pd 1.9 Cu catalysts exhibit excellent HER catalytic stability.

[0154] Application Example 3: Performance Testing of a Single Cell in PEM Water Electrolysis

[0155] Weigh the Ir prepared in Example 3 0.58 / Pd 1.9 7.9 mg of Cu electrocatalyst powder was added sequentially to deionized water, ethanol, and Nafion solution (5 wt%), and the three were mixed in a volume ratio of deionized water, ethanol, and Nafion solution of 1:0.13:9 to prepare a slurry. The concentration of the electrocatalyst in the slurry was 2 mg / cm³. -2 Spray to an effective area of ​​4cm² 2 The Nafion 212 membrane. The anode-side loading is 0.3 mg. Ir cm -2 Cathode spraying 0.2 mg cm -2 Commercial 60 wt% Pt / C. Membrane electrode assemblies (MEAs) were prepared by sandwiching the membrane electrode between two gas diffusion layers at 130 °C and 0.15 MPa for 2 minutes. The flow rate was 20 mL / min on a PSW 30-36 DC power supply. -1Ultrapure water was pumped into the anode side at a flow rate of [value missing], and the performance of the single cell was evaluated at 80°C. Simultaneously, a water electrolysis single cell was assembled and its performance was tested using commercial Ir black as a control MEA.

[0156] Figure 24 Ir prepared in Example 3 0.58 / Pd 1.9 Performance graphs of single-cell water electrolysis using Cu catalyst and commercial Ir black. (See figure) Figure 24 As shown, in 1A cm -2 When using Ir 0.58 / Pd 1.9 The Cu catalyst requires an electrolysis voltage of 1.69V for a single cell in water electrolysis, which is lower than that of commercial Ir black (1.79V), demonstrating its advantage as an anode catalyst for water electrolysis.

Claims

1. A method for preparing ultrafine iridium nanoparticles directly grown on a metal surface, characterized in that, Includes the following steps: (1) Mix the aqueous solution of the metal salt with the capping agent, surfactant and fuming hydrochloric acid to obtain a mixed solution; (2) After stirring and heating the mixed solution obtained in step (1) to a certain temperature, add the reducing agent I aqueous solution and keep it for a certain time to generate a sea urchin-shaped metal alloy; (3) Add iridium salt aqueous solution and reducing agent II to the solution obtained in step (2), keep the temperature constant, and continue stirring for a certain period of time; (4) Wash the mixed solution obtained in step (3) to obtain ultrafine iridium nanoparticles directly grown on the metal surface; The metal salt includes palladium salt and other metal salts, wherein the other metal salt is one or more of nickel salt, copper salt, and platinum salt; The reducing agent II is formic acid or acetic acid; The temperature in step (2) is 90~130 ℃, and the stirring time is 0.5~5 h; the molar ratio of the reducing agent I to the metal salt is 10:1~1:1; The stirring time in step (3) is 0.5 to 5 h; the molar ratio of iridium salt to metal salt is 2:1 to 1:30, and the volume ratio of reducing agent II to iridium salt aqueous solution is 1:1 to 5:1; The ultrafine iridium nanoparticles have a particle size of less than 5 nm.

2. The method for preparing ultrafine iridium nanoparticles directly grown on a metal surface according to claim 1, characterized in that, The nickel salt includes one of NiCl2·6H2O, Ni(H2PO2)2·6H2O, and NiN2O6·6H2O. The copper salt includes one of the following: C6H4Cu2O7·2.5H2O, C4H6CuO4, C6H8Cu2O7, CuC2O4, CuCl2·2H2O, CuCl2, Cu(NO3)2·6H2O, Cu(NO3)2·3H2O, CuSO4·5H2O, and CuSO4; The platinum salt includes one of H2PtCl6·6H2O, K2PtCl6, K2PtCl4, PtCl2, PtCl4, sodium tetrachloroplatinate(II) hydrate, hexachloroplatinate(IV) hydrate, N2H8PtCl6, H8Cl4N2Pt, and Cl6Na2Pt. The palladium salts include PdCl2, K2PdCl4, PdSO4, C4H6O4Pd, Pd(NO3)2, PdN2H6Cl2, Cl4Na2Pd, and Cl2H 12 One of N4Pd, H8Cl6N2Pd, and H8Cl4N2Pd; The iridium salt includes C 12 H 18 Ir3O 15 One of the following: C2H3O2·3H2O, IrCl3, Na2IrCl6·6H2O, K3IrCl6, K2IrCl6, Na2IrCl6, (NH4)2IrCl6, iridium(IV) chloride hydrate, iridium(III) chloride hydrate, sodium hexachloroiridium(III) acid hydrate, and hexachloroiridium(III) acid hydrate; The capping agent is KI or KBr; The surfactant is one of polyvinylpyrrolidone, a copolymer of propylene oxide and ethylene oxide F127, a triblock copolymer P123, and hexadecyltrimethylammonium bromide; the reducing agent I is one of citric acid, sodium citrate, ascorbic acid, sodium ascorbate, glucose, and sodium gluconate. The reducing agent II is formic acid or acetic acid.

3. The method for preparing ultrafine iridium nanoparticles directly grown on a metal surface according to claim 1, characterized in that, The molar ratio of the palladium salt to the other metal salts is 1:1 to 5:

1.

4. The method for preparing ultrafine iridium nanoparticles directly grown on a metal surface according to claim 1, characterized in that, In step (1), the molar concentration of the metal salt aqueous solution is 1~500 mM, the molar concentration of the capping agent in the mixed solution is 0.01~0.2 mM, and the molar concentration of the surfactant in the mixed solution is 0.001~0.05 mM.

5. The method for preparing ultrafine iridium nanoparticles directly grown on a metal surface according to claim 1, characterized in that, The washing in step (4) is performed using a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol in the mixed solution is 3:1 to 1:

1.

6. An ultrafine iridium nanoparticle directly grown on a metal surface by the preparation method according to any one of claims 1-5.

7. The application of the direct growth of ultrafine iridium nanoparticles on a metal surface as described in claim 6 in an electrolytic cell.

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