CN112626539A - Alloy electrocatalyst for ultra-stable PEM oxygen evolution reaction and preparation method thereof - Google Patents

Abstract

The invention discloses an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction, which is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir block alloy material, and the specific components of the alloy are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements. The invention also discloses a preparation method of the alloy electrocatalyst for the ultra-stable PEM oxygen evolution reaction. The method is simple, easy to operate and suitable for large-scale industrial production. The material can be directly used as an oxygen evolution reaction electrode, shows excellent electrochemical oxygen evolution activity in an acid medium, and can stably work for more than 1000 hours under the condition of high current density. The material can be used as the anode of an industrial acidic electrolyzed water hydrogen production device, and is beneficial to the large-scale application of the proton exchange membrane electrolyzed water technology.

Description

Alloy electrocatalyst for ultra-stable PEM oxygen evolution reaction and preparation method thereof

Technical Field

The invention relates to an alloy electrocatalyst and a preparation method thereof, belongs to the field of application of electrocatalysis materials, and particularly relates to an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction and a preparation method thereof.

Background

Under the trends of energy transformation and green development, the utilization efficiency of renewable energy sources such as hydropower, wind power, photovoltaic and biomass in China is remarkably improved, and the power generation installation and the power generation amount of the renewable energy sources in energy consumption are steadily increased. The proportion of renewable energy resources is steadily improved, and the consumption structure is promoted to clean low-carbon transformation. In the storage and use of energy based on renewable energy, electrohydrogen production will become an important component, and hydrogen will also be developed as an important energy carrier. The electrolytic water technology is the most practical method for producing hydrogen using renewable energy sources.

The water electrolysis hydrogen production technology is mainly divided into alkaline electrolytic cell hydrogen production, solid polymer Proton Exchange Membrane (PEM) electrolysis hydrogen production and high-temperature solid oxide electrolysis hydrogen production, wherein the PEM electrolysis hydrogen production can work under high current density, the hydrogen production purity is high, and the electrolysis efficiency is high. The current density of the existing commercial PEM electrolytic hydrogen production is 0.5-1.5A/cm²The hydrogen production by alkaline electrolysis is usually 0.3A/cm²And therefore, the volume of PEM electrolytic hydrogen production is smaller, and the distributed collection of renewable energy sources is easier. More importantly, the PEM hydrogen production can be operated under the power consumption of 0-120%, and the alkaline electrolysis hydrogen production is operated under the power consumption of 50-100%, so that the PEM hydrogen production is more easily matched with unstable power output generated by renewable energy sources.

Ir materials are believed to be the best oxygen evolution reactions under acidic conditionsElectrocatalyst, chinese patent CN 1874841 discloses a noble metal oxide catalyst for water electrolysis, the invented composite catalyst material comprising iridium oxide and optionally ruthenium oxide and a high surface area inorganic oxide (e.g. TiO)₂、Al₂O₃、ZrO₂And mixtures thereof). The examples show that the cell voltage is 1.5V, the current density is lower, 0.23mA/mg, and is better than that of the comparative example 1.48mA/mg, however, the method for measuring the catalyst performance in the invention is not universal. Chinese patent CN85107320 discloses a porous high surface area composite conductive catalytic material, which is a mixed catalytic material composed of platinum group metal oxide and at least one valve metal oxide. The examples show that the life of the electrodes is up to 85 hours. Chinese patent CN103055853 discloses a method for preparing water electrolysis oxygen evolution catalyst by using a silicon oxide molecular sieve as a template, and noble metal oxide nanoparticles of Ru or Ir are obtained, and when the noble metal oxide nanoparticles are used for a water electrolysis anode catalyst, the noble metal oxide nanoparticles have good oxygen evolution activity and stability. The above catalysts all have high specific surface area, thereby bringing about higher activity. However, the strong acidity of the proton exchange membrane is equivalent to 0.5M H₂SO₄Or 1M HClO₄Noble metals such as Ir and Ru and other inorganic oxides serving as anode catalysts are extremely easy to corrode in a strong oxidation environment and a strong acid medium, so that the catalysts are changed, and the overall performance of PEM electrolytic hydrogen production equipment is attenuated. In order to solve the problem of stability of the anode catalyst, the development of a catalyst with high activity and high stability still has great significance in the field of industrial PEM electrolyzed water.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction and a preparation method thereof. The invention aims to improve the intrinsic activity of the catalyst instead of the specific surface area of the catalyst. The material has excellent electro-catalytic activity of acid OER and ultrahigh stability, can be used as an anode of an industrial PEM water electrolysis hydrogen production device, is simple in preparation method and easy to operate, and is beneficial to large-scale application of PEM water electrolysis technology.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction, which is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir block alloy material.

Further, the specific components of the alloy are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements.

Further, the electrocatalytic activity of the alloy material reaches 10mA/cm in an acidic medium with pH of 0²The overpotential required for the catalytic current density is 300-650 mV.

Further, the electrocatalytic activity of the alloy material reaches 10mA/cm in an acidic medium with pH of 0²The overpotential range required by the catalytic current density is 300-350 mV.

Further, the alloy material can be 100mA/cm²The stable operation time under the current density condition is more than 1000 hours, and the overpotential rising rate ranges from 3 muV/h to 8 muV/h.

The invention provides a preparation method of an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction, wherein the alloy electrocatalyst is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir bulk alloy material, the specific components of the alloy are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, x and y are atomic percent of elements, the alloy electrocatalyst is directly cast and molded by adopting an electric arc melting technology, and the melting temperature is more than 3500 ℃.

Further, the method comprises the following steps:

(1) preparing a master alloy ingot: according to nominal components (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry of a master alloy, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements, alloy raw materials (with the purity of 98.0-99.9 wt%) are mixed, then arc melting is carried out under the protection of high-purity Ar atmosphere, the melting current is 200-300A, and in order to ensure the uniformity of the alloy components, the master alloy is repeatedly turned and melted in a furnace to obtain a master alloy ingot;

(2) alloy casting and forming: and (2) remelting the uniform master alloy ingot in the step (1) through arc melting, infiltrating the molten alloy into a water-cooled copper mold through a negative pressure suction casting method, and cooling the alloy melt in the copper mold to obtain the (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir electrocatalyst bar or plate with a certain shape and size.

Further, in the step (1), the master alloy is repeatedly turned and smelted in the furnace for more than four times to obtain a master alloy ingot.

The invention provides an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction, which is W₈₀Ir₂₀A bulk alloy material; where 80 and 20 are atomic percentages of the elements.

Further, the electrocatalytic activity of the alloy material reaches 10mA/cm in an acidic medium with pH of 0²The overpotential range required by the catalytic current density is 300-350 mV; the alloy material can be 100mA/cm²The stable operation time under the current density condition is more than 1000 hours, and the overpotential rising rate ranges from 3 muV/h to 8 muV/h.

Further, the preparation method comprises the following steps:

(1) preparing a master alloy ingot: according to the nominal composition W of the master alloy₈₀Ir₂₀80 and 20 are atomic percentages of elements, alloy raw materials (with the purity of 98.0-99.9 wt%) are mixed, arc melting is carried out under the protection of high-purity Ar atmosphere, the melting current is 200-300A, and in order to ensure that the alloy components are uniform, the master alloy is repeatedly turned and melted in a furnace to obtain a master alloy ingot;

(2) alloy casting and forming: remelting the uniform master alloy ingot in the step (1) by arc melting, infiltrating the molten alloy into a water-cooled copper mold by a negative pressure suction casting method, and cooling the alloy melt in the copper mold to obtain W₈₀Ir₂₀Electrocatalyst rods or plates.

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

(1) the catalyst is a block material, and compared with a powder material, the intrinsic activity of the catalyst is improved.

(2) The oxygen evolution reaction electrocatalyst prepared by the invention has ultrahigh stability under an acidic condition, and the problem of limitation of insufficient long-term service stability of the existing acidic oxygen evolution reaction electrocatalyst is solved.

(3) The method of electric arc melting is adopted for direct casting and molding, the preparation process is simple, complex chemical synthesis process is not needed, and the method is suitable for large-scale industrial production.

Drawings

FIG. 1 is W prepared in example 1₈₀Ir₂₀Linear sweep voltammogram of electrocatalyst material.

FIG. 2 is W prepared in example 1₈₀Ir₂₀The electrocatalyst material was at 100mA/cm²Voltage versus time plot under current density conditions.

FIG. 3 is the Hf prepared in example 7₈₀Ir₂₀Linear sweep voltammogram of electrocatalyst material.

Detailed Description

The alloy electrocatalyst for the ultra-stable PEM oxygen evolution reaction is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir block alloy material, and the design characteristics of the alloy components are that a noble metal active element Ir and a high-melting-point metal element, the specific components of the alloy are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, and x and y are atomic percent of the elements. The alloy material can be directly used as an anode material for oxygen evolution reaction, has excellent electrocatalytic activity and reaches 10mA/cm in an acid medium with pH of 0²The overpotential range required by the catalytic current density is 300-350 mV. It is used as acidic oxygen evolution electrocatalyst, shows ultrahigh stability and can be 100mA/cm²The stable operation time under the current density condition is more than 1000 hours, and the overpotential rising rate ranges from 3 muV/h to 8 muV/h.

The invention will now be further described with reference to the accompanying drawings and specific embodiments.

Example 1

In this example, the nominal composition of the alloy selected is W₈₀Ir₂₀The electrocatalyst material was prepared as follows:

(1) preparing a master alloy ingot: according to the nominal composition W of the master alloy₈₀Ir₂₀Alloy raw materials W and Ir (with the purity of 98.0-99.9 wt%) are mixed, arc melting is carried out under the protection of high-purity Ar atmosphere, the melting current is 200A-300A, and in order to ensure the uniformity of alloy components, the master alloy is repeatedly turned and melted for more than four times in a furnace to obtain a master alloy ingot.

(2) Alloy casting and forming: remelting the uniform master alloy ingot in the step (1) by arc melting, infiltrating the molten alloy into a water-cooled copper mold by a negative pressure suction casting method, and cooling the alloy melt in the copper mold to obtain W with the diameter of 2mm₈₀Ir₂₀An electrocatalyst rod.

The obtained alloy is subjected to acidic oxygen evolution reaction performance test, a three-electrode device is adopted for the test, and the W with a fixed exposed area₈₀Ir₂₀Alloy pattern (bare area 0.322 cm)²) As a working electrode, a counter electrode is a platinum wire electrode, a reference electrode is a standard Ag/AgCl electrode, an electrolyte is a 0.5mol/L sulfuric acid solution, and the scanning speed is 5 mV/s. As shown in FIG. 1, W₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as about 347 mV.

When the constant current test was performed on each electrode, the voltage-time curve was as shown in FIG. 2, and it was found that when the current density was 100mA/cm²W as prepared in example 1₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 6 muV/h within 1000 h. Demonstration of W prepared according to the invention₈₀Ir₂₀The alloy electrocatalyst has excellent stability of acidic oxygen evolution reaction.

Example 2

In this example, the nominal composition of the alloy selected is W₆₀Ir₄₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to acidic oxygen evolution reaction performance testA three electrode setup was tried, the test protocol was the same as in example 1, W₆₀Ir₄₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as about 300 mV. Preparation of the obtained W₆₀Ir₄₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 4 muV/h within 1000 h. Demonstration W₆₀Ir₄₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 3

In this example, Mo is the nominal component of the alloy₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test by adopting a three-electrode device, the test scheme is the same as that of the embodiment 1, and Mo₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as around 643 mV. Prepared Mo₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 7 muV/h within 1000 h. Prove Mo₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 4

In this example, the nominal alloy component selected is Nb₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test by adopting a three-electrode device, the test scheme is the same as that of the example 1, and Nb is₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is around 436mV lower. Prepared Nb₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for over 1000h in 0.5mol/L sulfuric acid electrolyte, and still maintain high electrocatalytic activity of 1000hThe rate of overpotential rise in hours is less than 8 μ V/h. Prove Nb₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 5

In this example, Ta is the nominal component of the alloy selected₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test by adopting a three-electrode device, the test scheme is the same as that of the embodiment 1, and Ta₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is around 398mV lower. Preparation of the obtained Ta₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 6 muV/h within 1000 h. Proving Ta₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 6

In this example, Zr is the nominal component of the alloy selected for use₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test, a three-electrode device is adopted in the test, the test scheme is the same as that of the embodiment 1, and Zr is adopted₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as 615mV or so. Preparation of the obtained Zr₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 7 muV/h within 1000 h. Zr₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 7

In this example, the nominal composition of the alloy selected is Hf₈₀Ir₂₀Preparation method of the electrocatalyst material andthe same applies to example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test, a three-electrode device is adopted in the test, the test scheme is the same as that of the embodiment 1, and Hf (hafnium) is adopted₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as around 451 mV. Prepared Hf₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 8 muV/h within 1000 h. As shown in FIG. 3, Hf₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 8

In this example, the nominal composition of the alloy selected is Re₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to an acid oxygen evolution reaction performance test by adopting a three-electrode device, the test scheme is the same as that of the example 1, and Re₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is low at around 340 mV. Preparation of the obtained Re₈₀Ir₂₀The alloy electrocatalyst electrode can stably operate for more than 1000h in 0.5mol/L sulfuric acid electrolyte, still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 8 muV/h within 1000 h. Re₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

Example 9

In this example, the nominal composition of the alloy we chose is Os₈₀Ir₂₀The preparation method of this electrocatalyst material is the same as in example 1.

The obtained alloy is subjected to acidic oxygen evolution reaction performance test by adopting a three-electrode device, the test scheme is the same as that of the embodiment 1, and Os is₈₀Ir₂₀The alloy electrode material reaches 10mA/cm²The overpotential required for catalytic current density is as low as about 301 mV. Preparing the obtained Os₈₀Ir₂₀Alloy (I)The electrocatalyst electrode can stably run for more than 1000h in 0.5mol/L sulfuric acid electrolyte, and still maintain high electrocatalytic activity, and the overpotential rising rate is lower than 5 muV/h within 1000 h. Os₈₀Ir₂₀The alloy electrode material has electrocatalytic oxygen evolution activity.

In other examples, (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir series electrocatalyst can be prepared according to the same method of this example, and different bar materials or plate materials with different components can be obtained by only changing the nominal components of raw material ingredients.

The present invention is not limited to the above-described embodiments, and various changes and modifications of the present invention are intended to be included within the scope of the claims and the equivalent technology of the present invention if they do not depart from the spirit and scope of the present invention.

Claims (10)

1. An alloy electrocatalyst for ultrastable PEM oxygen evolution reactions, characterized by: the alloy electrocatalyst is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir block alloy material.

2. The alloy electrocatalyst according to claim 1, wherein: the specific components of the alloy material are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements.

3. The alloy electrocatalyst according to claim 1, wherein: the electrocatalytic activity of the alloy material reaches 10mA/cm in an acid medium with pH of 0²The overpotential required for the catalytic current density is 300-650 mV.

4. The alloy electrocatalyst according to claim 1, wherein: the alloy material can be 100mA/cm²The stable running time under the current density condition exceeds 1000 hours, and the overpotential rising rate rangeEnclosing at 3-8 muV/h.

5. A preparation method of an alloy electrocatalyst for an ultra-stable PEM oxygen evolution reaction is disclosed, the alloy electrocatalyst is a (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir bulk alloy material, the specific components of the alloy are (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements, and the preparation method is characterized in that: the alloy is directly cast and formed by adopting an electric arc melting technology, and the melting temperature is more than 3500 ℃.

6. The method of claim 5, comprising the steps of:

(1) preparing a master alloy ingot: according to nominal components (W, Mo, Nb, Ta, Zr, Hf, Re, Os) x-Iry of a master alloy, x is more than or equal to 60 and less than or equal to 80, y is more than or equal to 20 and less than or equal to 40, wherein x and y are atomic percent of elements, alloy raw materials (with the purity of 98.0-99.9 wt%) are mixed, then arc melting is carried out under the protection of high-purity Ar atmosphere, the melting current is 200-300A, and in order to ensure the uniformity of the alloy components, the master alloy is repeatedly turned and melted in a furnace to obtain a master alloy ingot;

(2) alloy casting and forming: and (2) remelting the uniform master alloy ingot in the step (1) through arc melting, infiltrating the molten alloy into a water-cooled copper mold through a negative pressure suction casting method, and cooling the alloy melt in the copper mold to obtain the (W, Mo, Nb, Ta, Zr, Hf, Re, Os) -Ir electrocatalyst bar or plate.

7. The method of claim 6, wherein: in the step (1), the master alloy is repeatedly turned and smelted for four to ten times in the furnace to obtain a master alloy ingot.

8. An alloy electrocatalyst for ultrastable PEM oxygen evolution reactions, characterized by: the alloy electrocatalyst is W₈₀Ir₂₀A bulk alloy material; where 80 and 20 are atomic percentages of the elements.

9. According to the claimsThe alloy electrocatalyst according to claim 8, characterized in that: the electrocatalytic activity of the alloy material reaches 10mA/cm in an acid medium with pH of 0²The overpotential range required by the catalytic current density is 300-350 mV; the alloy material can be 100mA/cm²The stable operation time under the current density condition is more than 1000 hours, and the overpotential rising rate ranges from 3 muV/h to 8 muV/h.

10. The alloy electrocatalyst according to claim 8, wherein the method of preparation comprises the steps of:

(1) preparing a master alloy ingot: according to the nominal composition W of the master alloy₈₀Ir₂₀80 and 20 are atomic percentages of elements, alloy raw materials (with the purity of 98.0-99.9 wt%) are mixed, arc melting is carried out under the protection of high-purity Ar atmosphere, the melting current is 200-300A, and in order to ensure that the alloy components are uniform, the master alloy is repeatedly turned and melted in a furnace to obtain a master alloy ingot;

(2) alloy casting and forming: remelting the uniform master alloy ingot in the step (1) by arc melting, infiltrating the molten alloy into a water-cooled copper mold by a negative pressure suction casting method, and cooling the alloy melt in the copper mold to obtain W₈₀Ir₂₀Electrocatalyst rods or plates.

Images