A noble metal iridium hydrogen evolution electrocatalyst, a preparation method and application thereof

Abstract

The application provides a noble metal iridium hydrogen evolution electrocatalyst and a preparation method and application thereof, and belongs to the technical field of water electrolysis hydrogen evolution. The application provides a preparation method of a noble metal iridium hydrogen evolution electrocatalyst, which comprises the following steps: mixing a carbon carrier, a nitrogen source and a phosphorus source, performing first calcination, and obtaining a modified carbon carrier; the carbon carrier comprises carbon black, graphene and carbon nanotubes; the mass ratio of the carbon black, the graphene and the carbon nanotubes is (1-3):(5-8):(10-15); mixing the modified carbon carrier with an iridium salt, performing second calcination, and obtaining the noble metal iridium hydrogen evolution electrocatalyst. The carbon carrier is compounded in the application, and multiple carbon carriers can synergistically improve the catalytic activity of the hydrogen evolution electrocatalyst. The carbon carrier is modified by the nitrogen source and the phosphorus source, which serves as an anchoring site for the noble metal, so that the iridium is not easy to fall off in the water electrolysis hydrogen evolution reaction process, thereby further improving the catalytic activity and stability of the hydrogen evolution electrocatalyst.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis hydrogen evolution technology, specifically relating to a noble metal iridium hydrogen evolution electrocatalyst, its preparation method, and its application. Background Technology

[0002] With continuous technological innovation and progress, environmental pollution and other problems are worsening. There is an urgent need to develop clean and renewable energy sources to reduce dependence on fossil fuels. Currently, hydrogen energy is considered a relatively ideal clean energy source due to its high calorific value and the fact that its combustion product is water. Hydrogen evolution electrolysis (HER) is a highly efficient, environmentally friendly method for producing high-purity hydrogen. Developing hydrogen evolution electrocatalysts with low overpotentials is one of the important means to optimize this method.

[0003] Currently, hydrogen evolution catalysts are mainly noble metal-based catalysts. For example, patent CN202210314356.7 describes a catalyst comprising a conductive carbon support and noble metal nanoparticles uniformly supported on its surface. Although this technology has improved the catalytic activity of noble metal-based catalysts for hydrogen evolution to some extent, how to design and synthesize highly active noble metal-based catalysts remains one of the major challenges in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a noble metal iridium hydrogen evolution electrocatalyst, its preparation method, and its application. The noble metal iridium hydrogen evolution electrocatalyst prepared by the method provided by this invention exhibits excellent catalytic hydrogen evolution activity.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a noble metal iridium hydrogen evolution electrocatalyst, comprising the following steps: (1) A carbon support, a nitrogen source and a phosphorus source are mixed and subjected to a first calcination to obtain a modified carbon support; the carbon support includes carbon black, graphene and carbon nanotubes; the mass ratio of the carbon black, graphene and carbon nanotubes is (1~3):(5~8):(10~15). (2) The modified carbon support obtained in step (1) is mixed with iridium salt and subjected to a second calcination to obtain a noble metal iridium hydrogen evolution electrocatalyst.

[0006] Preferably, the mass ratio of carbon black, graphene and carbon nanotubes in step (1) is (1~2):(6~7):(12~14).

[0007] Preferably, the nitrogen source in step (1) is at least one of urea, melamine, dicyandiamide and diammonium phosphate.

[0008] Preferably, the phosphorus source in step (1) is sodium hypophosphite.

[0009] Preferably, in step (1), the mass ratio of carbon support, nitrogen source and phosphorus source is 1:(0.1~1.5):(2~3).

[0010] Preferably, the temperature of the first roasting in step (1) is 700~1100℃ and the time of the first roasting is 1~3h.

[0011] Preferably, the mass ratio of the carbon support in step (1) to the iridium salt in step (2) is 1:(0.01~0.5).

[0012] Preferably, the temperature of the second roasting in step (2) is 600~800℃ and the time of the second roasting is 1~3h.

[0013] The present invention also provides a noble metal iridium hydrogen evolution electrocatalyst prepared by the preparation method described in the above technical solution.

[0014] The present invention also provides the application of the noble metal iridium hydrogen evolution electrocatalyst described in the above technical solution in hydrogen production by water electrolysis.

[0015] This invention provides a method for preparing a noble metal iridium hydrogen evolution electrocatalyst, comprising the following steps: mixing a carbon support, a nitrogen source, and a phosphorus source, and performing a first calcination to obtain a modified carbon support; the carbon support includes carbon black, graphene, and carbon nanotubes; the mass ratio of the carbon black, graphene, and carbon nanotubes is (1~3):(5~8):(10~15); mixing the modified carbon support with an iridium salt, and performing a second calcination to obtain the noble metal iridium hydrogen evolution electrocatalyst. This invention, by compounding the carbon support, utilizes multiple carbon supports to synergistically improve the catalytic activity of the hydrogen evolution electrocatalyst; by modifying the carbon support with nitrogen and phosphorus sources as anchoring sites for the noble metal, the iridium is less likely to detach during the hydrogen evolution reaction of water electrolysis, thereby further improving the catalytic activity and stability of the hydrogen evolution electrocatalyst. Experimental results show that the hydrogen evolution electrocatalyst prepared by this invention exhibits good performance at a current density of 10 mA / cm². 2 The overpotential at that time was 27~32mV, and the Tafel slope was 34.1~37.1mV dec. -1 . Detailed Implementation

[0016] This invention provides a method for preparing a noble metal iridium hydrogen evolution electrocatalyst, comprising the following steps: (1) A carbon support, a nitrogen source and a phosphorus source are mixed and subjected to a first calcination to obtain a modified carbon support; the carbon support includes carbon black, graphene and carbon nanotubes; the mass ratio of the carbon black, graphene and carbon nanotubes is (1~3):(5~8):(10~15). (2) The modified carbon support obtained in step (1) is mixed with iridium salt and subjected to a second calcination to obtain a noble metal iridium hydrogen evolution electrocatalyst.

[0017] This invention does not impose any special restrictions on the source of the raw materials; commercially available products familiar to those skilled in the art can be used.

[0018] In this invention, the terms "first" and "second" have no special meaning and are only used to distinguish the various operations.

[0019] This invention involves mixing a carbon support, a nitrogen source, and a phosphorus source, followed by a first calcination to obtain a modified carbon support.

[0020] In this invention, the carbon support comprises carbon black, graphene, and carbon nanotubes; the mass ratio of carbon black, graphene, and carbon nanotubes is (1~3):(5~8):(10~15), preferably (1~2):(6~7):(12~14), and more preferably 1:6:14. By controlling the mass ratio of carbon black, graphene, and carbon nanotubes within the above range, this invention enables the three supports to work synergistically, thereby further improving catalytic activity.

[0021] In this invention, the average particle size of the carbon black is preferably 10-50 nm; the specific surface area of ​​the carbon black is preferably 100-500 m². 2 / g.

[0022] In this invention, the number of graphene layers is preferably less than 30; the thickness of the graphene sheet is preferably 10 nm; the size of the graphene is preferably 5 µm; and the graphene is preferably produced by Zhongke Times Nano.

[0023] In this invention, the outer diameter of the carbon nanotube is preferably 4-6 mm; the length of the carbon nanotube is preferably 0.5-2 µm; and the carbon nanotube is preferably produced by Zhongke Times Nano.

[0024] In this invention, the nitrogen source is preferably at least one selected from urea, melamine, dicyandiamide, and diammonium phosphate, more preferably melamine and dicyandiamide. In this invention, when the nitrogen source is melamine and dicyandiamide, the mass ratio of melamine to dicyandiamide is preferably 1:1. This invention modifies the carbon support using a nitrogen source. Nitrogen acts as an anchoring point for the noble metal, making it less likely for iridium to detach during the hydrogen evolution reaction in water electrolysis, thereby further improving the catalytic activity and stability of the hydrogen evolution electrocatalyst. When the nitrogen source is melamine and dicyandiamide, the catalytic activity and stability of the hydrogen evolution electrocatalyst can be synergistically improved.

[0025] In this invention, the phosphorus source is preferably sodium hypophosphite. This invention modifies the carbon support using a phosphorus source, with phosphorus acting as an anchoring point for the noble metal, making it less likely for iridium to detach during the hydrogen evolution reaction in water electrolysis, thereby further improving the catalytic activity and stability of the hydrogen evolution electrocatalyst.

[0026] In this invention, the preferred mass ratio of the carbon support, nitrogen source, and phosphorus source is 1:(0.1~1.5):(2~3), more preferably 1:(0.5~1.0):(2.5~3). By controlling the ratio of the three components within the above range, this invention can further improve the catalytic activity and stability of the hydrogen evolution electrocatalyst.

[0027] In this invention, the mixing of the carbon support, nitrogen source, and phosphorus source is preferably ball milling; the ball milling time is preferably 1-4 hours, more preferably 2-3 hours; the ball milling speed is preferably 300-1500 rpm, more preferably 500-1200 rpm. The ball milling method used in this invention improves the uniformity of the raw material mixing.

[0028] In this invention, the temperature of the first roasting is preferably 700~1100℃, more preferably 800~1000℃; the roasting time is preferably 1~3h, more preferably 2~3h.

[0029] In this invention, the first calcination is preferably carried out in an inert atmosphere; the inert atmosphere is preferably argon.

[0030] After obtaining the modified carbon support, the present invention mixes the modified carbon support with iridium salt and performs a second calcination to obtain a noble metal iridium hydrogen evolution electrocatalyst.

[0031] In this invention, the iridium salt is preferably iridium acetylacetonate. The iridium salt in this invention is a precursor to the noble metal iridium.

[0032] In this invention, the mass ratio of the carbon support to the iridium salt is preferably 1:(0.01~0.5), more preferably 1:(0.02~0.1), and even more preferably 1:(0.04~0.06).

[0033] In this invention, the mixing of the modified carbon support and the iridium salt is preferably ball milling; the ball milling time is preferably 1-4 hours, more preferably 2-3 hours; the ball milling speed is preferably 300-1500 rpm, more preferably 500-1200 rpm. The ball milling method used in this invention improves the uniformity of the raw material mixing.

[0034] In this invention, the second calcination temperature is preferably 600~800℃, more preferably 650~750℃; the second calcination time is preferably 1~3h, more preferably 2~3h.

[0035] In this invention, the second calcination is preferably carried out in an inert atmosphere; the inert atmosphere is preferably argon.

[0036] This invention improves the catalytic activity of hydrogen evolution electrocatalysts by compounding carbon supports and using multiple carbon supports in a synergistic manner. By modifying the carbon supports with nitrogen and phosphorus sources as anchoring sites for noble metals, iridium is less likely to detach during the hydrogen evolution reaction of water electrolysis, thereby further improving the catalytic activity and stability of the hydrogen evolution electrocatalyst.

[0037] The present invention also provides a noble metal iridium hydrogen evolution electrocatalyst prepared by the preparation method described in the above technical solution.

[0038] The noble metal iridium electrocatalyst for hydrogen evolution provided by this invention possesses excellent catalytic hydrogen evolution activity and stability.

[0039] The present invention also provides the application of the noble metal iridium hydrogen evolution electrocatalyst described in the above technical solution in hydrogen production by water electrolysis.

[0040] The present invention does not impose any special limitations on the operation of the noble metal iridium hydrogen evolution electrocatalyst in water electrolysis for hydrogen production; any operation known to those skilled in the art can be used.

[0041] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] Example 1 The preparation method of the noble metal iridium hydrogen evolution electrocatalyst consists of the following steps: (1) The carbon support, melamine, and sodium hypophosphite were ball-milled at 1200 rpm for 2 h, and then calcined at 800 °C under an argon atmosphere for 2 h to obtain the modified carbon support; wherein the carbon support is carbon black, graphene, and carbon nanotubes; the average particle size of the carbon black is 30 nm and the specific surface area is 250 m². 2 / g; the number of graphene layers is <30, the sheet thickness is 10nm, and the size is 5µm; the outer diameter of carbon nanotubes is 4~6mm, and the length is 0.5~2µm; the mass ratio of carbon black, graphene and carbon nanotubes is 1:6:14; the mass ratio of carbon support, nitrogen source and phosphorus source is 1:0.5:3; (2) The modified carbon support obtained in step (1) is ball-milled with iridium acetylacetonate at 1200 rpm for 2 h, and then calcined at 600 °C in an argon atmosphere for 2 h to obtain the noble metal iridium hydrogen evolution electrocatalyst; wherein the mass ratio of carbon support to iridium acetylacetonate is 1:0.02.

[0043] Comparative Example 1 Based on Example 1, the mass ratio of carbon black, graphene, and carbon nanotubes was changed to 1:6:6, while other conditions remained unchanged.

[0044] Comparative Example 2 Based on Example 1, the mass ratio of carbon black, graphene, and carbon nanotubes was changed to 1:4:4, while other conditions remained unchanged.

[0045] Comparative Example 3 Based on Example 1, the mass ratio of carbon black, graphene, and carbon nanotubes was changed to 2:3:3, while other conditions remained unchanged.

[0046] Comparative Example 4 Based on Example 1, carbon black was omitted, the total amount of carbon carrier remained unchanged, the mass ratio of graphene to carbon nanotubes remained unchanged, and other conditions remained unchanged.

[0047] Comparative Example 5 Based on Example 1, graphene was omitted, the total amount of carbon support remained unchanged, the mass ratio of carbon black to carbon nanotubes remained unchanged, and other conditions remained unchanged.

[0048] Comparative Example 6 Based on Example 1, carbon nanotubes are omitted, the total amount of carbon support remains unchanged, the mass ratio of carbon black to graphene remains unchanged, and other conditions remain unchanged.

[0049] Example 2 Based on Example 1, the nitrogen source was changed to melamine and dicyandiamide, with a mass ratio of melamine to dicyandiamide of 1:1. The total amount of nitrogen source remained unchanged, and other conditions remained unchanged.

[0050] Example 3 Based on Example 1, the nitrogen source was changed to dicyandiamide, while other conditions remained unchanged.

[0051] Example 4 Based on Example 1, the mass ratio of carbon support, nitrogen source and phosphorus source was changed to 1:0.1:2, while other conditions remained unchanged.

[0052] Example 5 Based on Example 1, the mass ratio of carbon support, nitrogen source and phosphorus source was changed to 1:1.5:2, while other conditions remained unchanged.

[0053] Electrocatalytic application: The noble metal iridium hydrogen evolution electrocatalysts prepared in Examples 1-5 and Comparative Examples 1-6 were dispersed in 500 μL of an alcohol-water mixture, and ultrasonicated to form a uniform black suspension. 10 μL of the suspension was transferred onto a glassy carbon electrode, allowed to air dry, and then 5 μL of 0.5% Nafion was added dropwise. In a three-electrode system (the glassy carbon electrode with the suspension added as the working electrode, the saturated Ag / AgCl electrode as the reference electrode, and the graphite electrode as the counter electrode), the linear sweep voltammetry curve of the electrocatalyst was tested using a 0.5 M H₂SO₄ solution after purging N₂ for 20 minutes as the electrolyte.

[0054] The noble metal iridium hydrogen evolution electrocatalysts prepared in Examples 1-5 and Comparative Examples 1-6 were used at a current density of 10 mA / cm². 2 The overpotential and Tafel slope at 10 mA / cm² are shown in Table 1. 2 The stability at that time is shown in Table 2.

[0055] Table 1. Electrocatalytic activity data of the noble metal iridium hydrogen evolution electrocatalysts prepared in Examples 1-5 and Comparative Examples 1-6.

[0056] As can be seen from Table 1, the present invention can further improve the catalytic activity of the catalyst by controlling the nitrogen source to be melamine and dicyandiamide; it can further improve the catalytic activity of the catalyst by controlling the mass ratio of carbon black, graphene and carbon nanotubes; and it can further improve the catalytic activity of the catalyst by controlling the mass ratio of carbon support, nitrogen source and phosphorus source.

[0057] Table 2 shows the stability data of the noble metal iridium hydrogen evolution electrocatalysts prepared in Examples 1-5 and Comparative Examples 1-6.

[0058] As can be seen from Table 2, the stability of the catalyst can be further improved by controlling the nitrogen source to be melamine and dicyandiamide; the stability of the catalyst can be further improved by controlling the mass ratio of carbon black, graphene and carbon nanotubes; and the stability of the catalyst can be further improved by controlling the mass ratio of carbon support, nitrogen source and phosphorus source.

[0059] As can be seen from the above embodiments, the hydrogen evolution electrocatalyst provided by the present invention has excellent catalytic activity and stability.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a noble metal iridium hydrogen evolution electrocatalyst, comprising the following steps: (1) A carbon support, a nitrogen source and a phosphorus source are mixed and subjected to a first calcination to obtain a modified carbon support; the carbon support includes carbon black, graphene and carbon nanotubes; the mass ratio of the carbon black, graphene and carbon nanotubes is (1~3):(5~8):(10~15). (2) The modified carbon support obtained in step (1) is mixed with iridium salt and subjected to a second calcination to obtain a noble metal iridium hydrogen evolution electrocatalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of carbon black, graphene and carbon nanotubes is (1~2):(6~7):(12~14).

3. The preparation method according to claim 1, characterized in that, In step (1), the nitrogen source is at least one of urea, melamine, dicyandiamide and diammonium phosphate.

4. The preparation method according to claim 1, characterized in that, In step (1), the phosphorus source is sodium hypophosphite.

5. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of carbon carrier, nitrogen source and phosphorus source is 1:(0.1~1.5):(2~3).

6. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the first roasting is 700~1100℃ and the time of the first roasting is 1~3h.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the carbon support in step (1) to the iridium salt in step (2) is 1:(0.01~0.5).

8. The preparation method according to claim 1, characterized in that, The temperature of the second roasting in step (2) is 600~800℃, and the roasting time is 1~3h.

9. The noble metal iridium hydrogen evolution electrocatalyst prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the noble metal iridium hydrogen evolution electrocatalyst according to claim 9 in hydrogen production by water electrolysis.

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