CN115805317A - A kind of ruthenium iridium alloy material and its preparation method and application - Google Patents

Abstract

The invention discloses a ruthenium-iridium alloy material and a preparation method and application thereof, wherein the ruthenium-iridium alloy material is prepared by the following method: adding iridium chloride and ruthenium chloride serving as metal sources into a mixed solution of N-methylpyrrolidone and formic acid, and fully stirring; heating and synthesizing the ruthenium-iridium alloy consisting of the ultra-small nano particles by a solvothermal method. The method takes iridium chloride and ruthenium chloride as metal sources, takes N-methyl pyrrolidone as a solvent, and synthesizes the ruthenium-iridium alloy with a fingerprint shape by a solvothermal method under the reduction action of formic acid.

Description

A kind of ruthenium iridium alloy material and its preparation method and application

technical field

The invention relates to the technical field of acidic electrochemical oxygen evolution, in particular to a ruthenium-iridium alloy material and its preparation method and application.

Background technique

Since the Industrial Revolution, fossil fuels such as petroleum and coal have become the main energy sources. Due to the excessive use of fossil fuels, serious environmental problems such as the greenhouse effect have been caused. Therefore, the realization of carbon emission reduction and the search for clean energy have received extensive attention. As a zero-carbon green energy, hydrogen energy has become a promising energy source. Therefore, hydrogen energy technology has been intensively studied in recent decades.

The acidic electrochemical oxygen evolution technology is an important part of the electrocatalytic hydrolysis synthesis hydrogen technology. After decades of research, there are still many technical problems. Electrochemical oxygen evolution is an anodic reaction for electrocatalytic hydrolysis to synthesize hydrogen. Since this reaction is a 4-electron transfer reaction, it is kinetically inert. Therefore, the preparation of acidic electrochemical oxygen evolution catalysts has become one of the bottlenecks in the development of electrocatalytic hydrolysis synthesis of hydrogen technology. Due to the higher requirements for the stability of the catalyst under acidic conditions, the currently better catalysts are mainly iridium-based catalysts. However, the intrinsic activity of iridium-based catalysts is insufficient, and it is difficult to meet the needs of industrial water electrolysis for hydrogen production.

Contents of the invention

Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is how to prepare a new catalyst material to improve the intrinsic activity and electrochemical stability of the acidic electrochemical oxygen evolution catalyst.

In order to solve the above-mentioned technical problems, the first aspect of the present invention provides a method for preparing a ruthenium-iridium alloy material, comprising the following steps:

S1. Add iridium chloride and ruthenium chloride as metal sources to the mixed solution of N-methylpyrrolidone and formic acid, and fully stir it;

S2. Raising the temperature and synthesizing a ruthenium-iridium alloy composed of ultra-small nanoparticles by a solvothermal method.

Further, in the step S1, the concentration of iridium chloride after mixing is less than or equal to 1.5 mg/mL.

Further, in the step S1, the concentration of ruthenium chloride after mixing is less than or equal to 1.5 mg/mL.

Further, in the step S1, the volume ratio of N-methylpyrrolidone and formic acid is 2:1˜4:1.

Further, in the step S2, the heating temperature is 100-120°C.

The second aspect of the present invention provides a ruthenium-iridium alloy material prepared by the above-mentioned preparation method.

The second aspect of the present invention provides an application of the above-mentioned ruthenium-iridium alloy material as a catalyst in an acidic electrocatalytic oxygen evolution reaction.

Further, when the ruthenium-iridium alloy material is used as a catalyst, the ruthenium-iridium alloy material is first dispersed in a solvent to obtain a catalyst solution, and the catalyst solution is coated on the working electrode.

Further, when the ruthenium-iridium alloy material is used as a catalyst, the working potential of the acidic electrocatalytic oxygen evolution reaction is 1.3-2.0V.

Further, when the ruthenium-iridium alloy material is used as a catalyst, when the current density is 10mA/ ^cm2 in 0.5mol/L sulfuric acid aqueous solution, the overpotential is less than 250mV, the constant current works for 150 hours, and the potential drop rate is less than 5%.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The preparation method of the present invention is simple and easy, using iridium chloride and ruthenium chloride as the metal source, using N-methylpyrrolidone as the solvent, and under the reduction of formic acid, the ultra-small nano The "fingerprint" ruthenium-iridium alloy composed of particles.

(2) The present invention forms ruthenium-iridium alloy by the iridium of ruthenium replacement surface, can regulate the structure of metal iridium and the electric charge distribution on its surface by synthesis, make ruthenium-iridium alloy have special morphology and optimized electronic structure, improve its property activity and stability.

(3) The ruthenium-iridium alloy of the present invention has excellent catalytic activity and excellent stability in the acidic electrocatalytic oxygen evolution reaction, and has good application prospects as an anode catalyst for hydrogen production by electrolysis of water with a proton exchange membrane.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the ruthenium-iridium alloy that the embodiment of the present invention 1 makes;

Fig. 2 is the transmission electron micrograph of the ruthenium-iridium alloy that the embodiment of the present invention 1 makes;

Fig. 3 is the high-resolution transmission electron micrograph of the ruthenium iridium alloy that the embodiment of the present invention 1 makes;

Fig. 4 is the element distribution figure of the ruthenium-iridium alloy that the embodiment of the present invention 1 makes;

Fig. 5 is the linear scanning curve graph of the material of the embodiment 1 of the present invention, comparative example 1 and comparative example 2 as catalyst in the acidic electrocatalytic oxygen evolution reaction;

Fig. 6 is a graph showing the stability test of the materials of Example 1 and Comparative Example 1 of the present invention as catalysts.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

It should be understood that the terminology described in the present invention is only used to describe specific embodiments, and is not used to limit the present invention. In addition, regarding the numerical ranges in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

It will be apparent to those skilled in the art that various modifications and changes can be made in the specific embodiments of the present invention described herein without departing from the scope or spirit of the present invention. Other embodiments will be apparent to the skilled person from the description of the present invention. The specification and examples in this application are exemplary only.

The specific embodiment of the present invention provides a kind of ruthenium-iridium alloy material its preparation method, with iridium chloride and ruthenium chloride as metal source, with N-methylpyrrolidone as solvent, synthesized by solvothermal method under the reduction of formic acid A "fingerprint" ruthenium-iridium alloy composed of ultra-small nanoparticles, in which the doping of ruthenium improves the intrinsic activity and stability of the iridium catalyst. The above preparation method is simple and feasible, and is synthesized in one step by a solvothermal method.

In a specific embodiment, the concentration of iridium chloride in the reaction system is less than or equal to 1.5mg/mL, the concentration of ruthenium chloride is less than or equal to 1.5mg/mL, and the volume ratio of N-methylpyrrolidone and formic acid is 2:1～4: 1. Iridium chloride and ruthenium chloride are fully mixed and heated to 100-120°C for reaction. Under the reduction of formic acid, ruthenium replaces the iridium on the surface to form a ruthenium-iridium alloy, which adjusts the structure of metal iridium and the charge distribution on the surface to improve its intrinsic activity and stability.

The above-mentioned ruthenium-iridium alloy material can be used as a catalyst in the acidic electrocatalytic oxygen evolution reaction. As a way of realization, the "fingerprint" ruthenium-iridium alloy material composed of ultra-small nanoparticles is dispersed in a solvent to obtain a catalyst solution, and the The catalyst solution is coated on the working electrode. The working potential of the acidic electrocatalytic oxygen evolution reaction is 1.3-2.0V; the solvent used is not limited, and as a realization method, the solvent is composed of deionized water, ethanol and a binder.

The ruthenium-iridium alloy has high acidic electrocatalytic oxygen evolution activity and high stability in the acidic electrocatalytic oxygen evolution reaction. When the current density is 10mA/ ^cm2 in 0.5mol/L sulfuric acid aqueous solution, the overpotential is less than 250mV, the constant current works for 150 hours, and the potential drop rate is less than 5%.

The technical effects of the present invention will be described below in conjunction with specific embodiments.

Example 1

The present embodiment prepares ruthenium-iridium alloy, and concrete process is as follows:

Dissolve 5 mg of iridium chloride and 5 mg of ruthenium chloride in a mixed solution of 5 ml of N-methylpyrrolidone and formic acid (3:1 by volume), stir well; heat the solution to 100° C. and maintain the temperature for 5 hours; wash and centrifuged three times, put into an oven, and dry at 70° C. for 12 hours to obtain ruthenium-iridium alloy powder.

The ruthenium-iridium alloy powder that the present embodiment makes is carried out X-ray diffraction analysis, and the result is as shown in Figure 1, can see the characteristic peak of metal ruthenium, iridium from Figure 1, proves that above-mentioned method has synthesized ruthenium-iridium alloy.

The ruthenium-iridium alloy powder prepared in this example was analyzed by transmission electron microscopy, and the test results are shown in Figures 2 and 3. It can be observed that the material is a ruthenium-iridium nanoparticle smaller than 1 nm, and its appearance is "fingerprint-like".

The ruthenium-iridium alloy material prepared in this embodiment is used as an electrocatalyst for acidic electrocatalytic oxygen evolution, and the process is as follows:

(1) Preparation of catalyst ink

Weigh 4 mg of the above-prepared ruthenium-iridium alloy powder and 4 mg of carbon paste powder, add to 735 μL of deionized water and 235 μL of ethanol, and add 30 μL of 5% Nafion117 solution, and ultrasonically disperse for half an hour to obtain catalyst ink.

(2) Linear scan test

The electrocatalytic performance of the catalyst was characterized using the electrochemical three-electrode system of Shanghai Chenhua CHI760E electrochemical workstation. Use 0.5 mol/L sulfuric acid aqueous solution as the electrolyte, platinum mesh electrode as the counter electrode, and 250 μL of catalytic ink is drop-coated on the hydrophilic carbon paper as the working electrode.

During the test, the reversible hydrogen electrode is a linear scan test in the potential range of 1.23-1.8V, and the results are as shown in Figure 3. ^When the current density of the ruthenium-iridium alloy catalyst in this embodiment is 10mA/cm , the overpotential is 237mV, indicating that The catalyst has high catalytic activity.

(3) Stability test

Carry out the stability test with the testing system described in above-mentioned (2), result as shown in Figure 4, the present embodiment ruthenium-iridium alloy catalyst is 10mA/ ^cm at current density Running 150 hours, potential does not have obvious decline, shows The catalyst has excellent stability.

Example 2

The present embodiment prepares ruthenium-iridium alloy, and concrete process is as follows:

Dissolve 1 mg of iridium chloride and 5 mg of ruthenium chloride in a mixed solution of 5 ml of N-methylpyrrolidone and formic acid (3:1 by volume), stir well; heat the solution to 110° C. and maintain the temperature for 5 hours; wash and centrifuged three times, put into an oven, and dry at 70° C. for 12 hours to obtain ruthenium-iridium alloy powder.

The ruthenium-iridium alloy material prepared in this example was used as an electrocatalyst for acidic electrocatalytic oxygen evolution, and the process was the same as in Example 1. When the current density is 10mA/ ^cm2 in 0.5mol/L sulfuric acid aqueous solution, the overpotential is 243mV; the potential does not drop significantly after 150 hours of constant current operation.

Example 3

The present embodiment prepares ruthenium-iridium alloy, and concrete process is as follows:

Dissolve 3.5 mg of iridium chloride and 2 mg of ruthenium chloride in a mixed solution of 5 ml of N-methylpyrrolidone and formic acid (3:1 by volume), and stir evenly; heat the solution to 120° C. and maintain the temperature for 5 hours; Wash and centrifuge three times, put into an oven, and dry at 70° C. for 12 hours to obtain ruthenium-iridium alloy powder.

The ruthenium-iridium alloy material prepared in this example was used as an electrocatalyst for acidic electrocatalytic oxygen evolution, and the process was the same as in Example 1. When the current density is 10mA/ ^cm2 in 0.5mol/L sulfuric acid aqueous solution, the overpotential is 246mV; the potential does not drop significantly after 150 hours of constant current operation.

Comparative example 1

In this comparative example, commercial iridium dioxide was used as an electrocatalyst for acidic electrocatalytic oxygen evolution, and the process was the same as in Example 1. Test result as shown in Figure 3 and Figure 4, when the catalyzer of comparative example 1 is 10mA/cm ^when current density, overpotential is obviously greater than the catalyzer of embodiment 1, shows that activity is lower; Constant current work 4 hours, catalyzer loses rapidly , indicating its poor stability.

Comparative example 2

In this embodiment, the preparation process of the material is as follows:

Dissolve 5 mg of iridium chloride in a mixed solution of 5 ml of N-methylpyrrolidone and formic acid (volume ratio is 3:1), stir well; heat the solution to 100° C. and maintain the temperature for 5 hours; wash and centrifuge three times, put Put it into an oven and dry it at 70°C for 12 hours to obtain metal powder.

The material prepared in this example was used as an electrocatalyst for acidic electrocatalytic oxygen evolution, and the process was the same as steps (1) and (2) in Example 1. The test results are shown in Figure 3. When the current density of the catalyst of Comparative Example 2 was 10mA/cm ² , the overpotential was greater than that of the catalyst of Example 1, indicating that the activity was lower.

Comparative example 3

In this embodiment, the preparation process of the material is as follows:

Dissolve 5 mg of ruthenium chloride in a mixed solution of 5 ml of N-methylpyrrolidone and formic acid (3:1 by volume), stir well; heat the solution to 100° C. and maintain this temperature for 5 hours; wash and centrifuge three times, and finally Put it into an oven and dry it at 70° C. for 12 hours, but no product was obtained. It shows that no metal nanoparticles are formed when only ruthenium chloride is added as the metal source.

Although the present invention is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims (10)

1. a preparation method of ruthenium-iridium alloy material, is characterized in that, comprises the following steps: S1. Add iridium chloride and ruthenium chloride as metal sources to the mixed solution of N-methylpyrrolidone and formic acid, and fully stir it; S2. Raising the temperature and synthesizing a ruthenium-iridium alloy composed of ultra-small nanoparticles by a solvothermal method. 2. The preparation method of ruthenium-iridium alloy material according to claim 1, characterized in that, in the step S1, the concentration of iridium chloride after mixing is less than or equal to 1.5 mg/mL. 3. The preparation method of ruthenium-iridium alloy material according to claim 1, characterized in that, in the step S1, the concentration of ruthenium chloride after mixing is less than or equal to 1.5 mg/mL. 4. The method for preparing a ruthenium-iridium alloy material according to claim 1, characterized in that, in the step S1, the volume ratio of N-methylpyrrolidone to formic acid is 2:1˜4:1. 5. The method for preparing the ruthenium-iridium alloy material according to any one of claims 1-4, characterized in that, in the step S2, the heating temperature is 100-120°C. 6. A ruthenium-iridium alloy material, characterized in that it is prepared by the preparation method according to any one of claims 1-5. 7. An application of the ruthenium-iridium alloy material as claimed in claim 6, wherein the ruthenium-iridium alloy material is used as a catalyst in the acidic electrocatalytic oxygen evolution reaction. 8. The application according to claim 7, wherein the ruthenium-iridium alloy material is dispersed in a solvent to obtain a catalyst solution, and the catalyst solution is coated on the working electrode. 9. The application according to claim 8, characterized in that the working potential of the acidic electrocatalytic oxygen evolution reaction is 1.3-2.0V. 10. application according to claim 9, is characterized in that, in the sulfuric acid aqueous solution of 0.5mol/L when current density is 10mA/cm ² , overpotential is less than 250mV, constant current work 150 hours, potential drop rate is less than 5% .

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