Preparation method of self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode

Abstract

The invention discloses a method for preparing a self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode, comprising the steps of: weighing 10 mmol NiCl2·6H2O and dissolving it in 10 mL aqueous solution to prepare a nickel chloride solution; and step 2: cutting a foamed iron (2×3 cm 2 ) is immersed in the above solution at room temperature for a period of time. During this process, NiFe‑O NAs will grow in situ on the surface of the foamed iron. After washing with clean water and drying in air at 60°C for 1h, the first nickel-iron-based electrode (NiFe‑O NAs / Fe foam) can be obtained; Step 3: In the chemical vapor deposition system, NiFe‑O NAs / Fe foam is placed downstream of the tube furnace, and a quartz boat loaded with 0.9g NaH2PO2 is placed at the upstream end of the tube furnace, and heated at 2°C min in a 30sccm argon atmosphere. ‑1 The sample was heated to 300°C at a heating rate and kept warm for a period of time to obtain the second nickel-iron-based electrode (NiFe-P NAs / Fe foam). The present invention prepared a robust catalytic electrode through a combination strategy of simple chloride etching growth and low-temperature phosphating, and achieved efficient seawater electrolysis with high current density.

Description

Technical Field

[0001] The invention relates to the technical field related to electrochemical catalytic materials, and specifically to a method for preparing a self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode. Background Art

[0002] The production of high-purity green hydrogen using water electrolysis technology can effectively respond to the energy and environmental crises caused by the massive consumption of fossil fuels. However, the large-scale implementation of this technology remains challenging due to the shortage of fresh water and the lack of high-performance and inexpensive electrodes. Seawater electrolysis is an attractive alternative to traditional freshwater electrolysis due to its abundance and low cost in nature. However, the undesirable chloride ion oxidation reaction that occurs simultaneously with seawater electrolysis greatly hinders the overall performance of seawater electrolysis. To address this issue, the development of efficient and robust alkaline seawater electrolysis catalysts is urgently needed.

[0003] Sustainable hydrogen production through water / seawater electrolysis requires the development of high-performance, inexpensive non-precious metal-based catalytic electrodes. Self-supporting catalytic electrodes have the advantages of high active material loading, sufficient exposure of active sites, and close bonding between catalyst and carrier, and show broad application prospects in high current density seawater electrolysis. Among them, nickel foam self-supported nickel-based hydroxides (hydroxyl oxides), sulfides, and phosphides show excellent corrosion resistance to chloride ions in seawater and good OER selective activity. However, the natural abundance of nickel on Earth is about 1.8%, which is much lower than iron (32%); combined with the environmental protection characteristics of iron, the design of foam iron self-supported non-precious metal electrocatalysts will be more suitable for industrial green hydrogen production. However, the foam iron-based catalytic electrodes of the prior art are difficult to achieve good electrolysis of alkaline seawater at high current density, and the cheap foam iron-based catalytic electrodes have low catalytic activity at high current density. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode to solve the problem that the foamed iron-based catalytic electrode prepared by the prior art mentioned in the above background technology is difficult to achieve efficient alkaline seawater electrolysis at a high current density.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a method for preparing a self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode, comprising the following raw materials and components, characterized in that: NiCl2·6H2O, NaH2PO2 and foamed iron, wherein one catalytic electrode is an amorphous nickel-iron-oxygen nanoarray (NiFe-O NAs / Fe foam) self-supported by foamed iron, and is used as an anode for the complete decomposition of seawater, and the other catalytic electrode is an amorphous nickel-iron-phosphorus nanoarray (NiFe-P NAs / Fe foam) self-supported by foamed iron, and is used as a cathode for the complete decomposition of seawater.

[0006] As a further technical solution, it is characterized by: comprising preparing a nickel chloride solution, corroding foamed iron to obtain NiFe-O NAs / Fe foam, and low-temperature phosphating NiFe-O NAs / Fe foam to obtain NiFe-P NAs / Fe foam; characterized by:

[0007] Step 1: Prepare nickel chloride solution; weigh 10 mmol NiCl2·6H2O and dissolve it in 10 mL aqueous solution to prepare nickel chloride solution;

[0008] Step 2: Soak the foam iron; cut out an area of ​​2×3cm 2 Foam iron, the cut foam iron is immersed in the above solution at room temperature for a period of time, during which NiFe-O NAs will grow in situ on the surface of the foam iron, and the electrode after immersion corrosion is repeatedly washed with water and dried in air at 60°C for 1h to obtain amorphous NiFe-O NAs / Fe foam with a high specific surface area;

[0009] Step 3: The preparation of NiFe-P NAs / Fe foam is obtained by low-temperature phosphating NiFe-O NAs / Fe foam in a chemical vapor deposition system, characterized in that NiFe-O NAs / Fe foam is placed at the downstream end of the tube furnace, and a quartz boat loaded with 0.9g NaH2PO2 powder is placed at the upstream end of the tube furnace. After the tube furnace is closed, the oxygen in the cavity is evacuated and heated at 2°C min in 30sccm argon. -1 The sample was heated to 300°C at a heating rate and kept warm for 0.25, 0.5, 1, and 2 h. After the reaction was completed, the system was slowly cooled to room temperature to obtain amorphous NiFe-P NAs / Fefoam with a high specific surface area.

[0010] As a further technical solution, it is characterized in that: after the foamed iron (Fe foam) is etched in a nickel chloride solution for just 5 minutes, an amorphous NiFe-O nanowire (NAs) array will be generated on the surface, and the amorphous NiFe-O NAs / Fe foam electrode can achieve high-speed oxygen evolution.

[0011] As a further technical solution, it is characterized in that: NiFe-O NAs / Fe foam is derived to produce highly active amorphous NiFe-P NAs / Fe foam, which can achieve high current density hydrogen evolution. The prepared NiFe-P nanowire array is still about 800 nm in length, has a porous structure on the surface, and is amorphous.

[0012] As a further technical solution, the feature is that the synthesized NiFe-P NAs / Fe foam and NiFe-ONAs / Fe foam are mainly made of cheap iron as raw material.

[0013] As a further technical solution, it is characterized in that: the synthesized NiFe-P||NiFe-O electrode pair only needs a voltage of 1.862V to reach 500mA cm in fully dissolved seawater. -2 The device can withstand high current density and can work stably for 100h at this current density.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention uses a combination of chloride etching growth and low-temperature phosphating to convert cheap iron foam into an efficient and robust catalytic electrode for efficient seawater electrolysis, helping to increase the market penetration of green hydrogen;

[0016] 2. After just 5 minutes of etching in nickel chloride solution, an amorphous NiFe-O nanowire (NAs) array will be generated on the surface of the foamed iron (Fe foam). The resulting amorphous NiFe-O NAs / Fe foam electrode can achieve high-speed oxygen evolution; Ni Fe-ONAs / Fe foam derives highly active amorphous NiFe-P NAs / Fe foam, which can achieve high current density oxygen evolution;

[0017] 3. The obtained NiFe-X(X=O,P)NAs / Fe foam is mainly made of cheap Fe as raw material, and the synthesized NiFe-P||NiFe-O electrode pair only needs a voltage of 1.862V to reach 500mA cm in fully dissolved seawater. -2 The device can work stably for 100 hours at a high current density.

[0018] 4. The present invention combines chloride etching growth with low-temperature phosphating to prepare efficient and robust catalytic electrodes for seawater electrolysis applications under high current density; at the same time, the preparation method of the present invention is simple, energy-saving and time-saving, which can effectively reduce the preparation cost and help promote the industrialization process of seawater electrolysis technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the synthesis and characterization of NiFe-O NAs and NiFe-P NAs catalysts supported by nickel foam of the present invention;

[0020] Figure 2 Schematic diagram of the OER performance of NiFe-O NAs / Fe foam prepared at different immersion times according to the structure of the present invention;

[0021] Figure 3 Schematic diagram of the OER performance of NiFe-O NAs / Fe foam prepared at different etching concentrations according to the structure of the present invention;

[0022] Figure 4 Schematic diagram of the HER performance of NiFe-P NAs / Fe foam prepared at different phosphating times according to the structure of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1: As a further technical solution, as described in step 1, 10 mmol NiCl2·6H2O was weighed and dissolved in 10 mL of aqueous solution to prepare a nickel chloride solution; foam iron (2×3 cm 2 ) were immersed in nickel chloride solution at room temperature for 5, 30, and 60 min to obtain NiFe-O NAs / Fe foam prepared at different immersion times. The OER performance of the foams was shown in Figure 2. Figure 2 shown.

[0025] Example 2: As a further technical solution, as described in step 1, 5, 10, and 20 mmol NiCl2·6H2O were weighed and dissolved in 10 mL of aqueous solution to prepare nickel chloride solution, and several pieces of foam iron (2×3 cm 2 ) were immersed in the above nickel chloride solutions of different concentrations at room temperature for five minutes to obtain NiFe-ONAs / Fe foams prepared at different etching concentrations. The OER performance of the foams was as follows: Figure 3 As shown; combined with implementation case 1, we obtained that the optimal preparation condition of NiFe-O NAs / Fe foam is to weigh 10 mmol and dissolve it in 10 mL aqueous solution to prepare nickel chloride solution, and let it stand at room temperature for 5 min.

[0026] Example 3: As a further technical solution, as described in step 2, 0.9 g NaH2PO2 was weighed and placed in a quartz boat and placed in the upstream of the tube furnace, and the NiFe-O NAs / Fe foam electrode was placed in the downstream of the tube furnace. The maximum reaction temperature was 300°C, and the holding time was 0.25, 0.5, 1, and 2 h. NiFe-P NAs / Fe foam prepared with different phosphating times was obtained, and its HER performance was as follows: Figure 4As shown in the figure, it can be seen that the optimal phosphating time is 0.5h.

[0027] By combining chloride corrosion with phosphating, amorphous NiFe-X (X = O / P) NAs electrocatalysts were grown in situ on the surface of iron foam. Benefiting from the amorphous structure, fast charge transfer, and the synergistic effect of Ni-Fe-O and Ni-Fe-P, the obtained NiFe-O NAs / Fe foam and NiFe-P NAs / Fe foam have high intrinsic activity and can respectively achieve oxygen evolution and hydrogen evolution at high current. In addition, the synthesized NiFe-P||NiFe-O electrode pair only needs a voltage of 1.862 V to reach 500 mA cm in fully dissolved seawater. -2 The electrode pair can work stably for 100 h at a current density of 1000 mA cm -2 The dual-electrode electrolyzer also showed competitive performance among all noble metal-free electrocatalysts at current densities of 2.5 Å / s. This provides a solution for the production of high-performance and low-cost catalytic electrodes, which may contribute to the large-scale production of green hydrogen.

[0028] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode, comprising the following raw materials and components: Features: NiCl 2 6H 2 O、NaH 2 PO 2 and iron foam, wherein one catalytic electrode is NiFe-O NAs / Fe foam and is used as an anode for the complete decomposition of seawater, and the other catalytic electrode is NiFe-PNAs / Fe foam and is used as a cathode for the complete decomposition of seawater; The preparation method comprises preparing a nickel chloride solution, corroding foamed iron to obtain NiFe-O NAs / Fe foam, and phosphating the NiFe-O NAs / Fe foam at low temperature to obtain NiFe-P NAs / Fe foam. The preparation method comprises: Step 1: Prepare nickel chloride solution; weigh 10 mmol NiCl 2 6H 2 O is dissolved in 10 mL of aqueous solution to prepare nickel chloride solution; Step 2: Soak the foam iron; cut out an area of ​​2×3cm 2 Foam iron, the cut-to-order foam iron is immersed in the above solution at room temperature for a period of time, during which NiFe-O NAs will grow in situ on the surface of the foam iron, and the electrode after immersion corrosion is repeatedly washed with water and dried in air at 60°C for 1h to obtain an amorphous NiFe-ONAs / Fe foam with a high specific surface area; Step 3: The preparation of NiFe-P NAs / Fe foam is obtained by low-temperature phosphating NiFe-ONAs / Fe foam in a chemical vapor deposition system, characterized in that NiFe-O NAs / Fe foam is placed at the downstream end of a tube furnace, and a quartz boat is used to load 0.9 g NaH 2 PO 2 The powder was placed at the upstream end of the tube furnace. After the tube furnace was closed, the oxygen in the chamber was evacuated and heated at 2 °C min in 30 sccm argon. -1 The sample was heated to 300°C at a heating rate and kept warm for 0.25, 0.5, 1, and 2 h. After the reaction was completed, the system was slowly cooled to room temperature to obtain amorphous NiFe-PNAs / Fefoam with a high specific surface area.

2. The method for preparing the self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode according to claim 1, Features: After just 5 minutes of etching in nickel chloride solution, an amorphous NiFe-O nanowire (NAs) array will be generated on the surface of foamed iron (Fe foam). The amorphous NiFe-O NAs / Fe foam electrode can achieve high-speed oxygen evolution.

3. The method for preparing the self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode according to claim 1, Features: NiFe-O NAs / Fe foam derives highly active amorphous NiFe-PNAs / Fe foam, which can achieve high current density hydrogen evolution. The prepared NiFe-P nanowire array is still about 800nm ​​long, has a porous structure on the surface, and is amorphous.

4. The method for preparing the self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode according to claim 1, Features: The synthesized NiFe-P NAs / Fe foam and NiFe-ONAs / Fe foam are mainly made of cheap iron as raw material.

5. The method for preparing the self-supporting amorphous nickel-iron-based seawater electrolysis catalytic electrode according to claim 1, Features: The synthesized NiFe-P||NiFe-O electrode pair only needs 1.862 V to reach 500 mA cm in fully dissolved seawater. -2 The device can withstand high current density and can work stably for 100h at this current density.

Images