A nano-porous Ni 33 Ir2@ZANI alloy and a method of making the same

Abstract

The application provides a kind of nanoporous Ni 33 Ir2@ZANI alloy and its preparation method belong to the technical field of electrode catalytic material. The application first uses arc melting technology to prepare Zr 55 Al 10 Ni 33 Ir2 alloy ingot, after the alloy strip is obtained by the tape casting process, the Zr and Al on the surface of the alloy strip are corroded by the dealloying method to obtain the nanoporous Ni 33 Ir2@ZANI alloy can be used as an anode oxygen evolution reaction electrocatalyst for water electrolysis. Under alkaline conditions, the catalytic activity, stability and durability of the oxygen evolution reaction electrocatalyst prepared by the application are much higher than those of IrO2 / C. At the same time, the catalyst prepared by the application has low noble metal content, simple preparation method and is suitable for large-scale production. In addition, the catalyst has self-supporting ability and good electrical conductivity, and can be directly used as an anode material for water electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of electrode catalyst materials technology, specifically relating to a nanoporous Ni as an electrocatalyst for the oxygen evolution reaction. 33 Ir2@ZANI(Zr 55 Al 10 Ni 33 Ir2 alloy and its preparation method. Background Technology

[0002] Water electrolysis stands out among various hydrogen production methods due to its widely available raw materials; however, its anodic reaction (oxygen evolution reaction) is inherently slow and typically requires the addition of a catalyst. Currently, the noble metal-containing catalyst IrO2 / C is one of the best oxygen evolution reaction catalysts, but the low abundance of iridium (Ir) and its poor stability limit its widespread application as an oxygen evolution reaction catalyst. Therefore, developing novel, highly efficient, stable oxygen evolution reaction catalysts with low noble metal content is crucial.

[0003] Nickel (Ni), as an abundant transition metal, possesses a unique 3d orbital structure (3d 8 4s 2 Alloying with Ir can alter the d orbital structure of Ir (4f). 14 5d 7 6s 2 This allows for the regulation of the relative rates of adsorption and desorption of intermediates in the oxygen evolution reaction, thereby increasing the reaction rate. Furthermore, based on first-principles calculations using density functional theory, Ni... 33 Ir2 is theoretically a catalyst with high catalytic activity. In water electrolysis, the electrode materials themselves do not participate in the electrochemical reaction, so the catalyst for the oxygen evolution reaction can itself serve as the anode material. Studies have found that Ni... 33 Zr2 alloy prepared by combining Zr and Al 55 Al 10 Ni 33 Ir2 quaternary alloy strips are self-supporting and can be directly used as electrode materials by combining them with electrode clips. This eliminates the need to prepare the catalyst alloy into particles and then coat them onto the surface of the electrode material, thus eliminating the risk of catalyst failure due to particle shedding.

[0004] Dealloying is an effective method for preparing three-dimensional nanoporous structures. Controlling the dealloying time and temperature ensures the controllability of the morphology, surface composition, and size of the prepared product, resulting in a stable structure suitable for mass production. In the aforementioned quaternary alloy strips, using dealloying, by controlling the concentration of the etchant hydrofluoric acid and the etching time, the resulting alloy strip exhibits three layers: an etched layer, a substrate layer, and another etched layer, where the substrate layer is unetched Zr. 55 Al 10Ni 33 Ir2 quaternary alloy, the remaining Ni in the corrosion layer 33 Ir2 alloy, this alloy strip is simply referred to as Ni 33 Ir2@ZANI. Considering that three-layered catalysts can provide abundant active sites during water electrolysis, however, there is still much research on nanoporous Ni catalysts prepared using dealloying methods. 33 There are no reports yet of Ir2@ZANI alloys being used as electrocatalysts for oxygen evolution reactions.

[0005] Recently, nanoporous alloy particles have attracted widespread attention due to their abundant catalytic active sites, convenient electron transport channels, and excellent oxygen evolution reaction catalytic activity. However, particulate catalysts have the following problems: 1. They need to be fixed on the electrode surface by a Nafion membrane, but the Nafion membrane will hinder the contact between water molecules and the catalyst active sites; 2. The catalyst's stable working time is less than 12 hours; 3. Some particles will fall off after long-term use. Summary of the Invention

[0006] The purpose of this invention is to provide a nanoporous Ni as an electrocatalyst for the oxygen evolution reaction. 33 Ir2@ZANI alloy and its preparation method.

[0007] The technical solution of the present invention is as follows:

[0008] A nanoporous Ni as an electrocatalyst for the oxygen evolution reaction 33 Ir2@ZANI alloy, with a Ni surface layer 33 Ir2 nanoporous Zr 55 Al 10 Ni 33 Ir2 alloy strips are obtained by arc melting of Zr. 55 Al 10 Ni 33 Ir2 quaternary alloy raw material, then obtained by dealloying to obtain Ni surface layer 33 Ir2 nanoporous Zr 55 Al 10 Ni 33 Ir2 alloy strips, denoted as nanoporous Ni 33 Ir2@ZANI.

[0009] A nanoporous Ni as an electrocatalyst for the oxygen evolution reaction 33 The preparation method of Ir2@ZANI alloy includes the following steps:

[0010] 1. According to stoichiometric ratio Zr 55 Al 10 Ni 33Ir2 calculates the required mass of each element and then prepares the ingredients;

[0011] 2. Place the prepared raw materials into a water-cooled copper crucible electric arc melting furnace, and reduce the pressure inside the furnace cavity to 5*10. -3 By introducing 0.4 atm of high-purity argon gas into the furnace cavity and repeating the melting process multiple times, Zr can be obtained. 55 Al 10 Ni 33 Ir2 alloy ingot;

[0012] 3. The obtained alloy ingot is cut and placed into a quartz glass tube. A Zr alloy with a thickness of 40±2μm and a width of 1.0±0.2mm is obtained through a strip spinning process. 55 Al 10 Ni 33 Ir2 alloy strips;

[0013] 4. Cut strips to a length of 10.0 mm and place them in an HF solution of a certain concentration. Maintain the temperature at 25°C and strictly control the reaction time to 900 s. After 900 s, separate the solid and liquid phases. Wash the reacted strips multiple times in anhydrous ethanol, then repeatedly rinse them with ultrapure water. Finally, vacuum dry the resulting alloy strips to obtain the nanoporous Ni. 33 Ir2@ZANI alloy.

[0014] Furthermore, in step 2, the arc melting current is 80-100A.

[0015] Furthermore, in step 3, Zr is prepared using a strip spinning process. 55 Al 10 Ni 33 When using Ir2 alloy strips, the linear velocity is 15 m / s.

[0016] Furthermore, in step 4, the concentration of the HF solution is 0.029 mol / L.

[0017] Furthermore, in step 4, the sample is placed in a vacuum drying oven and dried at room temperature for 12 hours.

[0018] Compared with the prior art, the present invention has the following main advantages and beneficial effects:

[0019] 1. The nanoporous Ni of the present invention 33 Ir2@ZANI alloy catalysts have low noble metal content, simple preparation methods, and are suitable for large-scale production;

[0020] 2. The nanoporous Ni of the present invention 33 Compared with commercial IrO2 / C catalysts, Ir2@ZANI alloy catalysts have significant advantages in catalytic activity, durability and stability.

[0021] 3. The nanoporous Ni of the present invention 33 The Ir2@ZANI alloy catalyst has self-supporting capabilities and good electrical conductivity, making it suitable as an anode material for water electrolysis.

[0022] 4. Compared with common precious metal catalysts, zirconium and aluminum are both low-cost products. Furthermore, alloying with nickel can significantly reduce the cost of the catalyst. Attached Figure Description

[0023] Figure 1 The nanoporous Ni of Example 1 of this invention 33 Cross-sectional scanning electron microscopy characterization results of Ir2@ZANI alloy (a), surface scanning electron microscopy characterization results (b), ordinary (c), and high-resolution (d) transmission electron microscopy characterization results of surface corrosion layer.

[0024] Figure 2 In this context, 'a' represents the nanoporous Ni from Example 1 of this invention. 33 LSV plots of Ir2@ZANI alloy and commercial IrO2 / C; Figure 2 In the figure, b is the durability test diagram of Embodiment 1 of the present invention.

[0025] Figure 3 In this context, 'a' represents the nanoporous Ni from Example 1 of this invention. 33 Tafel plots (a) and chronopotential plots (b) of Ir2@ZANI alloy and commercial IrO2 / C.

[0026] Figure 4 The LSV curves of the products obtained in Examples 2-5 are shown.

[0027] Figure 5 The LSV curves of the products obtained in Examples 6-7 are shown. Detailed Implementation

[0028] The nanoporous Ni of the present invention 33 The microstructure of the Ir2@ZANI alloy was characterized by scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The nanoporous Ni alloy described in this invention... 33 The oxygen evolution reaction (OER) of the Ir2@ZANI alloy electrocatalyst was tested on an electrochemical workstation (CHI760E) using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronovoltammetry (CP). During the tests, nanoporous Ni nanoparticles with a thickness of 40±2 μm, a length of 10.0 mm, and a width of 1.0±0.2 mm were used. 33The Ir2@ZANI alloy strip was fixed as the working electrode using a platinum electrode clamp. The resulting working electrode, along with a platinum electrode counter and a mercury / mercury oxide reference electrode, formed a three-electrode system. Oxygen evolution reaction (OER) tests were conducted in a 1 mol / L KOH solution saturated with oxygen. In the IrO2 / C used, IrO2 was sourced from Alfa Esa Ltd., and C was graphene oxide from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0029] Example 1:

[0030] Step 1: According to the stoichiometric ratio of Zr 55 Al 10 Ni 33 Ir2 calculates the required mass of each elemental metal and prepares the ingredients to an accuracy of 0.1 mg, ensuring that the purity of each elemental metal is above 99.99%.

[0031] Step 2: Place the prepared raw materials into a water-cooled copper crucible electric arc melting furnace, and use a vacuum pump to reduce the pressure inside the furnace cavity to 5*10. -3 At 0.4 atm, high-purity argon gas was introduced into the furnace cavity, and the current was increased to 80 A to begin melting. During the melting process, an electromagnetic stirrer was used to ensure uniform distribution of elements in the molten alloy. The flow was stopped after 15 seconds, and the block sample was turned over after cooling. The above melting process was repeated 4 times to obtain Zr. 55 Al 10 Ni 33 Ir2 alloy ingot.

[0032] Step 3: Cut the alloy ingot obtained in Step 2, insert it into a specially made quartz glass tube, fix it inside a high-frequency electromagnetic heating coil, and reduce the pressure inside the furnace cavity to 5*10. -3 Pa, 0.2 atm of high-purity argon gas was introduced into the furnace cavity, the rotation speed of the single-roller rotary rapid quenching device was increased to 1500 r / min (linear velocity 15 m / s), and the current of the high-frequency electromagnetic heating coil was increased to melt and spray out the alloy, resulting in a Zr alloy with a thickness of approximately 40 μm and a width of approximately 1.0 mm. 55 Al 10 Ni 33 Ir2 alloy strips.

[0033] Step 4: Cut the material obtained in Step 3 into two strips with a length of 10.0 mm. Place them in a 0.029 mol / L HF solution, control the temperature at 25℃, and strictly control the reaction time to 900 s. After 900 s, separate the solid and liquid phases. Wash the reacted strips three times in anhydrous ethanol, then wash them repeatedly three times with ultrapure water. Place the resulting alloy strips in a vacuum drying oven and dry them at room temperature for 12 h to obtain the nanoporous Ni of this invention. 33 Ir2@ZANI alloy.

[0034] Step 5: A nanoporous Ni nanofiber with a thickness of 40 μm and dimensions of 10.0 x 1.0 mm is formed. 33 The Ir2@ZANI alloy strip was fixed as the working electrode using a platinum electrode clamp. This working electrode, along with a platinum counter electrode and a mercury / mercury oxide reference electrode, formed a three-electrode system. The oxygen evolution reaction was then tested in a 1 mol / L KOH solution saturated with oxygen.

[0035] Figure 1 For the prepared nanoporous Ni 33 SEM and TEM images of the Ir2@ZANI alloy are shown. Image a is a cross-sectional SEM image, demonstrating the three-layer structure of the material; image b is a surface SEM image, showing the formation of a porous structure in the surface corrosion layer; image c is a TEM image, further revealing the porous structure of the surface corrosion layer; and image d is a high-resolution TEM image, where the ordered lattice fringes indicate the presence of Ni. 33 Ir2 alloys exhibit an ordered structure.

[0036] Figure 2 For the prepared nanoporous Ni 33 LSV plots and durability test plots for Ir2@ZANI alloy and commercial IrO2 / C. Figure 2 In the diagram, 'a' represents the LSV plot of both, generating a 10 mA / cm² plot. 2 The required overpotentials for the current densities are 224.4 mV and 302.9 mV, respectively. Figure 2 In the durability test diagram (b), the overpotential changes were 0.04 mV and 40.3 mV, respectively.

[0037] Figure 3 For the prepared nanoporous Ni 33 Tafel plots and chronopotential plots of Ir2@ZANI alloy and commercial IrO2 / C Figure 3 In the figure, 'a' represents the Tafel curves of the two graphs, with Tafel slopes of 112.02 mV and dec respectively. -1 and 198.47mV dec -1 ; Figure 3 In the diagram, b represents the chronopotential graphs of the two graphs, with settling times of 13 hours and 4 hours, respectively.

[0038] Example 2:

[0039] The reaction time was changed from "strictly controlled at 900 s" to "strictly controlled at 60 s" during the preparation process. Other preparation conditions remained the same as in Example 1, resulting in Ni with morphology and properties similar to those in Example 1. 33 Ir2@ZANI.

[0040] Figure 4 The LSV test plot for Example 2 is given, showing a generation of 10 mA / cm. 2 The required overpotential for the current density is 248.8 mV.

[0041] Example 3:

[0042] The preparation process was modified so that "the reaction time was strictly controlled at 900 s" was changed to "the reaction time was strictly controlled at 300 s". Other preparation conditions were the same as in Example 1, and Ni with morphology and properties similar to those in Example 1 was obtained. 33 Ir2@ZANI.

[0043] Figure 4 The LSV test plot of Example 3 is given, showing a generation of 10 mA / cm 2 The required overpotential for the current density is 235.4 mV.

[0044] Example 4:

[0045] The reaction time was changed from "strictly controlled at 900 s" to "strictly controlled at 600 s" during the preparation process. Other preparation conditions remained the same as in Example 1, resulting in Ni with morphology and properties similar to those in Example 1. 33 Ir2@ZANI.

[0046] Figure 4 The LSV test plot for Example 4 is given, showing a generation of 10 mA / cm. 2 The required overpotential for the current density is 216.6 mV.

[0047] Example 5:

[0048] The reaction time was changed from "strictly controlled at 900 s" to "strictly controlled at 1200 s" during the preparation process. Other preparation conditions remained the same as in Example 1, resulting in Ni with morphology and properties similar to those in Example 1. 33 Ir2@ZANI.

[0049] Figure 4 The LSV test plot for Example 4 is given, showing a generation of 10 mA / cm. 2 The required overpotential for the current density is 234.4 mV.

[0050] Example 6:

[0051] During the preparation process, "according to the stoichiometric ratio of Zr" 55 Al 10 Ni 33 "Ir2" should be changed to "according to stoichiometric ratio Zr" 55 Al 10 Ni 35The other preparation conditions were the same as in Example 1, resulting in Ni with morphology and properties similar to those in Example 1. 33 Ir2@ZANI.

[0052] Figure 5 The LSV test plot of Example 6 is given, showing a generation of 10 mA / cm. 2 The required overpotential for the current density is 302.9 mV.

[0053] Example 7:

[0054] During the preparation process, "according to the stoichiometric ratio of Zr" 55 Al 10 Ni 33 "Ir2" should be changed to "according to stoichiometric ratio Zr" 55 Al 10 Ni 31 Ir4” was prepared under the same conditions as in Example 1, yielding Ni with morphology and properties similar to those in Example 1. 33 Ir2@ZANI.

[0055] Figure 5 The LSV test plot of Example 7 is given, showing a generation of 10 mA / cm. 2 The required overpotential for the current density is 208.4 mV.

Claims

1. A nanoporous Ni 33 Ir2@ZANI alloy, characterized in that, Its surface layer is Ni 33 Ir2 nanoporous Zr 55 Al 10 Ni 33 Ir2 alloy strips are obtained by arc melting of Zr. 55 Al 10 Ni 33 Ir2 quaternary alloy material, then obtained by dealloying to have a Ni surface layer 33 Ir2 nanoporous Zr 55 Al 10 Ni 33 Ir2 alloy strips, denoted as nanoporous Ni 33 Ir2@ZANI.

2. A nanoporous Ni 33 The method for preparing Ir2@ZANI alloy is characterized by, It includes the following steps: Step 1, according to the stoichiometric ratio of Zr 55 Al 10 Ni 33 Ir2 calculates the required mass of each element and then prepares the ingredients; Step 2: Obtain Zr by electric arc melting. 55 Al 10 Ni 33 Ir2 alloy ingot; Step 3: Cut the obtained alloy ingot and obtain Zr through a strip spinning process. 55 Al 10 Ni 33 Ir2 alloy strips; Step 4: Cut strips of a certain length and place them in an HF solution of a certain concentration. Control the temperature at 25°C and the reaction time at 900 seconds. After 900 seconds, separate the solid and liquid, wash, and vacuum dry to obtain the nanoporous Ni. 33 Ir2@ZANI alloy.

3. The method as described in claim 2, characterized in that, In step 2, the ingredients are placed into a water-cooled copper crucible electric arc melting furnace, and the pressure inside the furnace cavity is reduced to 5*10. -3 Pa, high-purity argon gas of 0.4 atm is introduced into the furnace cavity, the arc melting current is set to 80~100A, and the melting is repeated multiple times to obtain the alloy Zr. 55 Al 10 Ni 33 Ir2 ingots.

4. The method as described in claim 2, characterized in that, In step 3, Zr is prepared using a strip spinning process. 55 Al 10 Ni 33 When using Ir2 alloy strips, the linear velocity is 15 m / s.

5. The method as described in claim 2, characterized in that, In step 4, the concentration of the HF solution is 0.029 mol / L.

6. The method as described in claim 2, characterized in that, In step 4, place it in a vacuum drying oven and dry it at room temperature for 12 hours.

7. The nanoporous Ni as described in claim 1 33 Application of Ir2@ZANI alloy as an electrocatalyst for oxygen evolution reaction.

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