Method for preparing a platinum monolayer electrode by electrodeposition and electrode

Abstract

The application discloses a method for preparing a platinum monatomic loaded electrode by electrodeposition and the electrode. First, anodic etching is performed on the foamed nickel in an electrolyte solution, and the etched foamed nickel is cleaned with alkali. Then, the etched foamed nickel is placed in a solution containing nickel and iron ion precursors to grow a NiFe LDH film. The foamed nickel electrode loaded with the NiFe LDH is subjected to cathodic deposition in an alkaline solution containing chloroplatinic acid root to prepare a NiFe LDH electrode loaded with platinum monatomic (Pt SAs). The method can quickly prepare the NiFe LDH catalyst uniformly loaded with platinum monatomic at room temperature by means of the cathodic reduction method. The NiFe LDH loaded with the Pt SAs has a special coordination structure, which enhances the activity of the composite material in the electrocatalytic hydrogen evolution and oxygen evolution reactions. The preparation method can be expected to introduce platinum monatomic into various LDH electrodes and further enhance the electrocatalytic activity of the electrodes.

Description

TECHNICAL FIELD

[0001] The present application relates to the preparation of an electrocatalytic electrode, in particular to a method for preparing a platinum monatomic atom loaded nickel-iron layered double hydroxide electrode and the electrode. BACKGROUND

[0002] With the growth of global energy demand and the intensification of environmental pollution problems, the development of efficient and sustainable energy conversion and storage technologies has become a current research hotspot. Among them, water electrolysis to produce hydrogen as a clean and renewable energy acquisition method has received widespread attention. However, the slow kinetics of water decomposition reaction (including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER)) makes the development of efficient electrocatalysts a key factor for the large-scale application of this technology.

[0003] Platinum (Pt) is widely used in electrocatalytic reactions due to its excellent catalytic performance, especially in HER, which exhibits extremely low overpotential and excellent stability. However, due to the scarcity and high price of platinum, its large-scale application is limited. Therefore, researchers have been working to develop low-platinum or even platinum-free catalysts to reduce costs and improve catalytic efficiency. In recent years, single-atom catalysts (SACs) have become an ideal catalytic material due to their maximum utilization of noble metal atoms and excellent electrocatalytic performance. By precisely regulating the interaction between single-atom active sites and supports, the catalytic performance can be significantly improved, and the stability of the catalyst can be enhanced.

[0004] Among the many support materials, nickel-iron layered double hydroxide is widely studied and applied in OER catalysts due to its large specific surface area, abundant active sites, and good activity. In addition, by loading metal clusters, quantum dots or compounding with other materials, the electrocatalytic activity of the material can be further improved. However, how to construct an efficient, stable and uniformly loaded single-atom platinum catalyst on a nickel foam substrate is an important challenge currently faced. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a method for preparing a platinum monatomic atom loaded electrode by electrodeposition and the electrode.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A method for preparing a platinum monatomic atom loaded electrode by electrodeposition, comprising the following steps:

[0008] 1) sequentially using acetone, hydrochloric acid and water to ultrasonic clean the foamed nickel, the cleaned foamed nickel is used as a working electrode, a silver / silver chloride electrode is used as a reference electrode, and a platinum sheet is used as a counter electrode to form a three-electrode system; then, the foamed nickel electrode is immersed in a sodium nitrate solution containing oxalic acid to perform anodic etching, and the etched foamed nickel is sequentially rinsed with lye and deionized water to obtain a pretreated foamed nickel electrode;

[0009] 2) the pretreated foamed nickel electrode is immersed in a mixed solution of ferrous ions (Fe²⁺) and nickel ions (Ni²⁺), and after constant temperature reaction, it is taken out and rinsed with deionized water to obtain a foamed nickel electrode with grown nickel-iron layered double hydroxide;

[0010] 3) the foamed nickel electrode with grown nickel-iron layered double hydroxide is used as a working electrode, a silver / silver chloride electrode is used as a reference electrode, and a platinum sheet is used as a counter electrode to form a three-electrode system; cathodic deposition is performed, the cathodic deposition solution is chloroplatinic acid solution, and sodium hydroxide solution is used to adjust the pH to alkaline; after deposition is completed, the working electrode is rinsed with deionized water and placed in an oven for drying to obtain a nickel-iron layered double hydroxide electrode loaded with platinum single atoms.

[0011] The concentration of oxalic acid in the sodium nitrate solution containing oxalic acid is 0.001-0.1 mol / L -1 , and the concentration of sodium nitrate is 0.01-1 mol / L -1 .

[0012] The potential of anodic etching is 0.8-2.0 V, and the etching time is 1-10 min.

[0013] The source of ferrous ions is one or more of ferrous sulfate, ferrous acetate and ferrous chloride; and the source of nickel ions is one or more of nickel nitrate, nickel sulfate and nickel chloride.

[0014] The concentration of ferrous ions is 0.001-0.2 mol / L -1 , and the concentration of nickel ions is 0.002-0.4 mol / L -1 .

[0015] In step 2), the constant temperature reaction temperature is 25-70℃, and the reaction time is 10-120 min.

[0016] In step 3), the cathodic deposition potential is-0.5--2.0 V, and the deposition time is 30-180 s.

[0017] In step 3), the concentration of chloroplatinic acid solution is 0.0001-0.05 mol / L -1 .

[0018] The platinum monatomic electrode prepared according to the method is uniformly loaded with platinum monatomic on a nickel-iron layered double hydroxide, improves the catalytic performance of the electrode, reduces the use amount of platinum, and is used for electrolysis of water.

[0019] The beneficial effects of the present application are:

[0020] Through the process of anodic etching and growth of nickel-iron layered double hydroxide, the electrochemical activity of the nickel foam electrode is greatly improved, and the platinum monatomic is provided with an anchoring matrix, so that the uniform loading of platinum monatomic is realized. By loading platinum monatomic on the nickel-iron layered double hydroxide, not only the catalytic performance of the electrode is improved, but also the use amount of platinum is effectively reduced, and the noble metal resources are saved. The present application realizes the preparation of low-cost and high-efficiency electrode, and provides a new solution for the development of high-efficiency and low-cost water electrolysis technology, and has wide application prospect in the field of new energy.

[0021] Of course, any technical solution of the present application does not necessarily achieve all the beneficial effects above. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1(a) is a SEM image of the nickel-iron double metal hydroxide electrode loaded with platinum monatomic;

[0023] Fig. 1(b) is an EDS-Mapping image of the nickel-iron double metal hydroxide loaded with platinum monatomic.

[0024] Figure 2 STEM-HAADF is a high-angle annular dark field imaging of scanning transmission electron microscopy.

[0025] Figure 3 XRD is an XRD image of the nickel-iron double metal hydroxide loaded with platinum monatomic.

[0026] Figure 4 Linear sweep voltammetry is a linear sweep voltammetry curve of the nickel-iron double metal hydroxide electrode loaded with platinum monatomic. DETAILED DESCRIPTION

[0027] This invention discloses a method for preparing a nickel-iron layered bimetallic hydroxide (NiFe LDH) electrode loaded with platinum single atoms. First, nickel foam is anoly etched in an electrolyte solution, and then the etched nickel foam is cleaned with an alkali. Next, the etched nickel foam is placed in a precursor solution containing nickel and iron ions to grow a NiFe LDH thin film. The NiFe LDH-loaded nickel foam electrode is then cathodically deposited in an alkaline solution containing chloroplatinate ions to prepare a NiFe LDH electrode loaded with platinum single atoms (Pt SAs). This method utilizes cathodic reduction to rapidly prepare a uniformly platinum-loaded NiFe LDH catalyst at room temperature. The electrodeposited Pt SAs-loaded NiFe LDH exhibits a unique coordination structure, enhancing the electrocatalytic activity of its composite material for hydrogen evolution and oxygen evolution reactions. This preparation method holds promise for introducing platinum single atoms into various LDH electrodes and further enhancing their electrocatalytic activity. Example 1

[0028] 1) The nickel foam was ultrasonically cleaned sequentially using acetone, hydrochloric acid, and water. The cleaned nickel foam was used as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode, forming a three-electrode system. Then, the nickel foam was immersed in 0.05 mol / L... -1 Oxalic acid and 0.1 mol / L -1 Anodic etching was performed for 5 min at 1.5 V in a sodium nitrate mixed solution. The etched nickel foam was then rinsed sequentially with alkaline solution and deionized water to obtain the pretreated nickel foam electrode.

[0029] 2) Immerse the pretreated nickel foam electrode in 0.01 mol L... -1 Ferrous sulfate and 0.02 mol L -1 The nickel nitrate was reacted in a mixed solution at 50 degrees Celsius for 1 h, then removed and rinsed with deionized water to obtain a foam nickel electrode with grown nickel-iron layered bimetallic hydroxide.

[0030] 3) A three-electrode system was formed by using the electrode for growing nickel-iron layered bimetallic hydroxide as the working electrode, the silver / silver chloride electrode as the reference electrode, and the platinum sheet as the counter electrode. Cathodic deposition was performed at -1.3 V for 90 s using a 0.001 mol / L cathodic deposition solution. -1 The electrode was prepared with chloroplatinic acid solution, and the pH was adjusted to 12 using sodium hydroxide solution. After deposition, the electrode was rinsed with deionized water and dried in an oven at 60 degrees Celsius for 4 hours to obtain a nickel-iron layered bimetallic hydroxide electrode loaded with platinum single atoms.

[0031] The prepared samples were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Figure 1(a) shows a large number of nanoflower structures growing on the surface of the nickel-iron layered bimetallic hydroxide electrode loaded with platinum single atoms. Figure 1(b) shows EDS data indicating the presence of uniformly distributed Ni, Fe, Pt, and O signals on the sample surface, confirming the Pt loading. Figure 2 The presence of single-atom Pt was observed using high-angle annular dark-field imaging (STEM-HAADF) with scanning transmission electron microscopy. Figure 3 X-ray diffraction (XRD) results confirmed that the synthesized nanoflower structure was a NiFe LDH phase, demonstrating that this method can successfully prepare nickel-iron layered bimetallic hydroxide electrodes loaded with platinum single atoms. Figure 4 Linear sweep voltammetry curves show that the nickel-iron layered bimetallic hydroxide electrode loaded with platinum single atoms exhibits excellent electrocatalytic activity for both hydrogen evolution and oxygen evolution. Example 2

[0032] 1) The nickel foam was ultrasonically cleaned sequentially using acetone, hydrochloric acid, and water. The cleaned nickel foam was used as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode, forming a three-electrode system. Then, the nickel foam was immersed in 0.01 mol L⁻¹ water. -1 Oxalic acid and 0.1 mol / L -1 In a mixed sodium nitrate solution, anodic etching was performed at 0.8 / 1.2 / 1.4 / 1.6 / 1.8 / 2.0 V for 5 min, respectively. The etched nickel foam was then rinsed sequentially with alkaline solution and deionized water to obtain the pretreated nickel foam electrode.

[0033] Steps 2) and 3) are detailed in Example 1. The nickel-iron layered bimetallic hydroxide electrodes loaded with platinum single atoms after etching at different anode potentials all exhibit good OER and HER activities, as shown in Table 1.

[0034] Table 1. Effect of Anode Etching Potential

[0035] Example 3

[0036] 1) The nickel foam was ultrasonically cleaned sequentially using acetone, hydrochloric acid, and water. The cleaned nickel foam was used as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode, forming a three-electrode system. Then, the nickel foam was immersed in 0.001 / 0.1 mol / L... -1 Oxalic acid and 0.01 / 1 mol / L -1 In a sodium nitrate mixed solution, anodic etching was performed at 1.5V for 5 min. The etched nickel foam was then rinsed sequentially with alkaline solution and deionized water to obtain the pretreated nickel foam electrode.

[0037] Step 2) and Step 3) refer to the specific steps of Example 1, and the anodic etching solution and the time of loading platinum monatomic nickel-iron layered double hydroxide electrode both have good OER and HER activity, as shown in Table 2.

[0038] Table 2 Influence of anodic etching solution and time

[0039] Example 4

[0040] 1) Clean the foam nickel by ultrasonic cleaning with acetone, hydrochloric acid and water in turn. The cleaned foam nickel is used as a working electrode, a silver / silver chloride electrode is used as a reference electrode, and a platinum sheet is used as a counter electrode to form a three-electrode system. Then, the foam nickel is immersed in a mixed solution of 0.01 mol L -1 oxalic acid and 0.1 moL L -1 sodium nitrate, and anodic etching is carried out at 1.5 V for 1 / 3 / 5 / 8 / 10 min, respectively. The etched foam nickel is rinsed with alkaline solution and deionized water in turn to obtain a pretreated foam nickel electrode.

[0041] Step 2) and Step 3) refer to the specific steps of Example 1, and the anodic etching solution and the time of loading platinum monatomic nickel-iron layered double hydroxide electrode both have good OER and HER activity, as shown in Table 2.

[0042] Table 3 Influence of anodic etching time

[0043] Example 5

[0044] 1) The specific steps refer to Example 1;

[0045] 2) The pretreated foam nickel electrode is immersed in a mixed solution of 0.001 / 0.2 mol L -1 ferrous sulfate and 0.002 / 0.4 mol L -1 nickel nitrate, and after 25 / 70 degrees Celsius reaction for 10 / 120 min, it is taken out and rinsed with deionized water to obtain a foam nickel electrode with grown nickel-iron layered double hydroxide;

[0046] 3) The specific steps refer to Example 1.

[0047] Different nickel-iron ion concentrations and reaction temperatures and times can successfully prepare nickel-iron layered double hydroxide, and do not affect the subsequent loading of platinum monatomic atoms, and the electrode still has good OER and HER activity, as shown in Table 4.

[0048] Table 4 Influence of different NiFe LDH preparation conditions

[0049] Example 6

[0050] Steps 1) and 2) refer to the specific steps of Example 1;

[0051] 3) The electrode growing nickel-iron layered double hydroxide was used as the working electrode, a silver / silver chloride electrode was used as the reference electrode, and a platinum sheet was used as the counter electrode to form a three-electrode system. Cathodic deposition was performed at -0.5 / -1.0 / -1.5 / -2.0 V for 30 / 60 / 120 / 180 s, and the cathodic deposition solution was 0.001 mol / L H2PtCl6 solution, and the pH was adjusted to 12 using a sodium hydroxide solution. After deposition was completed, the electrode was rinsed with deionized water and placed in an oven at 60 degrees Celsius for drying for 4 h to obtain a platinum single-atom-loaded nickel-iron layered double hydroxide electrode. -1 chloroplatinic acid solution, and the pH was adjusted to 12 using a sodium hydroxide solution. After deposition was completed, the electrode was rinsed with deionized water and placed in an oven at 60 degrees Celsius for drying for 4 h to obtain a platinum single-atom-loaded nickel-iron layered double hydroxide electrode.

[0052] Different cathodic deposition potentials and deposition times can successfully prepare platinum single-atom-loaded nickel-iron layered double hydroxide, and the electrode still has good OER and HER activity, as shown in Table 5.

[0053] Table 5 Influence of different deposition potentials and deposition times

[0054] Example 7

[0055] Steps 1) and 2) refer to the specific steps of Example 1;

[0056] 3) The electrode growing nickel-iron layered double hydroxide was used as the working electrode, a silver / silver chloride electrode was used as the reference electrode, and a platinum sheet was used as the counter electrode to form a three-electrode system. Cathodic deposition was performed at -1.3 V for 90 s, and the cathodic deposition solution was 0.0001 / 0.001 / 0.01 / 0.05 mol / L H2PtCl6 solution, and the pH was adjusted to 12 using a sodium hydroxide solution. After deposition was completed, the electrode was rinsed with deionized water and placed in an oven at 60 degrees Celsius for drying for 4 h to obtain a platinum single-atom-loaded nickel-iron layered double hydroxide electrode. -1 chloroplatinic acid solution, and the pH was adjusted to 12 using a sodium hydroxide solution. After deposition was completed, the electrode was rinsed with deionized water and placed in an oven at 60 degrees Celsius for drying for 4 h to obtain a platinum single-atom-loaded nickel-iron layered double hydroxide electrode.

[0057] Different chloroplatinic acid concentrations can successfully prepare platinum single-atom-loaded nickel-iron layered double hydroxide, and the electrode still has good OER and HER activity, as shown in Table 6.

[0058] Table 6 Influence of different chloroplatinic acid concentrations

[0059]

[0060] The above examples are only used to explain the present application, but not limit the present application, any modification and change of the present application, which falls into the protection scope of the present application, is within the protection scope of the present application.

Claims

1. A method for the preparation of a platinum monolayer electrode by electrodeposition, characterized in that, Comprise the following steps: 1) sequentially ultrasonic cleaning the foamed nickel with acetone, hydrochloric acid and water, using the cleaned foamed nickel as a working electrode, a silver / silver chloride electrode as a reference electrode, and a platinum sheet as a counter electrode to form a three-electrode system; then, immersing the foamed nickel electrode into a sodium nitrate solution containing oxalic acid to perform anodic etching, and sequentially rinsing the etched foamed nickel with lye and deionized water to obtain a pretreated foamed nickel electrode; 2) immersing the pretreated foamed nickel electrode into a mixed solution of ferrous ions (Fe²⁺) and nickel ions (Ni²⁺), taking it out after constant temperature reaction, and rinsing it with deionized water to obtain a foamed nickel electrode with grown nickel-iron layered double hydroxide; 3) using the foamed nickel electrode with grown nickel-iron layered double hydroxide as a working electrode, a silver / silver chloride electrode as a reference electrode, and a platinum sheet as a counter electrode to form a three-electrode system; performing cathodic deposition, with a chloroplatinic acid solution as the cathodic deposition solution, and using a sodium hydroxide solution to adjust the pH to alkaline; after deposition, rinsing with deionized water, and placing the working electrode into an oven for drying to obtain a nickel-iron layered double hydroxide electrode loaded with platinum single atoms.

2. The method of claim 1, wherein, The concentration of oxalic acid in the sodium nitrate solution containing oxalic acid is 0.001-0.1 mol / L -1 , and the concentration of sodium nitrate is 0.01-1 mol / L -1 .

3. The method of claim 1, wherein, The potential of the anodic etching is 0.8-2.0 V, and the etching time is 1-10 min.

4. The method of claim 1, wherein, The source of the ferrous ions is one or more of ferrous sulfate, ferrous acetate, and ferrous chloride; and the source of the nickel ions is one or more of nickel nitrate, nickel sulfate, and nickel chloride.

5. The method of claim 1, wherein, The concentration of ferrous ions is 0.001-0.2 mol / L -1 The concentration of nickel ions is 0.002-0.4 mol / L -1 .

6. The method of claim 1, wherein, In step 2), the constant temperature reaction temperature is 25-70℃, and the reaction time is 10-120 min.

7. The method of claim 1, wherein, In step 3), the cathodic deposition potential is -0.5--2.0 V, and the deposition time is 30-180 s.

8. The method of claim 1, wherein, Step 3) the concentration of the chloroplatinic acid solution is 0.0001-0.05 mol L -1 .

Images