A method for preparing a multi-scale porous electrode with high activity and high conductivity

Abstract

The application relates to a preparation method of a multi-scale porous electrode with high activity and high conductivity, and relates to a preparation method of a multi-scale porous electrode with high activity and high conductivity.The application solves the technical problems of the existing OER electrocatalytic electrode surface smoothness, low activity and low conductivity.The application first utilizes selective laser melting to carry out a 3D printing preparation process of an electrode support, then utilizes an electrolyte activation solution to carry out secondary treatment, is called in-situ electrochemical activation treatment, realizes composite preparation of the multi-scale porous electrode, the smoothness of the originally smooth porous electrode surface is destroyed through the constant-voltage in-situ electrochemical activation process, the electrode support surface becomes rough, the electrode surface presents a nanoscale microstructure morphology, the surface structure doubles the specific surface area of the electrode structure, and further increases the activation sites of chemical reactions, so that the electronic conductivity of the electrode and the electrocatalytic activity of large-current electrolysis application can be enhanced.

Description

Technical Field

[0001] This invention relates to a method for preparing a multi-scale porous electrode with high activity and high conductivity. Background Technology

[0002] With global efforts to combat environmental pollution, developing clean and renewable energy sources and improving energy efficiency are essential, particularly in the electrolysis of water to produce hydrogen and oxygen. Currently, the low energy efficiency of the oxygen evolution reaction (OER) at the anode results in very low energy output. Optimizing electrode structure and developing highly active OER electrocatalytic electrodes are crucial for reducing the anode energy barrier and improving energy efficiency. To achieve high current density OER electrocatalysis for industrial applications, OER electrodes must simultaneously meet several requirements: high inherent activity and a large effective electrochemical active surface area, high conductivity, rapid transport of electrolytes and bubbles, and good corrosion resistance under strong oxidizing conditions. Traditional electrochemical catalytic electrodes have nearly smooth surfaces, resulting in relatively low reaction rates during the reaction process. Summary of the Invention

[0003] The present invention aims to solve the technical problems of existing OER electrocatalytic electrodes, such as smooth surface, low activity, and low conductivity, and provides a method for preparing a multi-scale porous electrode with high activity and high conductivity.

[0004] The method for preparing the multi-scale porous electrode with high activity and high conductivity of the present invention is carried out according to the following steps:

[0005] I. A micron-scale porous electrode support structure is prepared using selective laser melting 3D printing technology. This porous electrode support structure can achieve a micron-scale pore structure morphology, and the overall support and frame are also micron-scale structures.

[0006] 2. The porous electrode support structure prepared in step 1 is placed into an electrolyte solution to carry out a constant voltage electrochemical activation process to modify the surface of the electrode material and obtain a nanoscale micro-rough surface morphology. Then the electrode is washed multiple times in deionized water solution and finally dried to obtain a multi-scale porous electrode.

[0007] The electrolyte solution is an aqueous solution of ammonium chloride.

[0008] This invention first utilizes selective laser melting (SLM) for the 3D printing fabrication of electrode supports. The second step involves a secondary treatment using a self-developed electrolyte activation solution, termed in-situ electrochemical activation, which enables the composite fabrication of multi-scale porous electrodes. Through this constant-pressure in-situ electrochemical activation process, the smooth surface of the originally porous electrode is disrupted, the electrode support surface becomes roughened, and the electrode surface exhibits a nanoscale microstructure with an electrochemical activation layer. Scanning electron microscopy (SEM) analysis reveals a nanoscale microstructure. This surface structure significantly increases the specific surface area of ​​the electrode structure and further enlarges the activation sites for chemical reactions, enhancing the electrode's electronic conductivity and electrocatalytic activity for high-current electrolysis applications. Furthermore, the increased specific surface area allows for the acquisition of a large surface area and robust porous electrode support with less material consumption.

[0009] The multi-scale porous electrode prepared by this invention exhibits excellent electrochemical activity and high conductivity, and demonstrates good durability at low overvoltage potentials. It enables ultra-high current electrolysis of water for oxygen evolution reaction (OER), largely fulfilling the requirement for highly active OER reactions, reducing losses, and improving energy efficiency. The technical route and working principle of this invention are illustrated in the following diagram. Figure 1 As shown.

[0010] The multi-scale porous electrode of the present invention maintains the same reactivity as the initial reaction and exhibits excellent stability even after multiple cycles under optimal high current operating conditions.

[0011] The multi-scale porous electrode prepared in this invention was used for OER catalysis, achieving an A·cm⁻¹ ionization at a low overpotential of 290 mV to 300 mV. -2 ~1.6A·cm -2 It has a high current density and maintains good stability under high operating current density during nearly 50 hours of operation.

[0012] This invention selects an aqueous solution of NH4Cl as the electrolyte. It is weakly acidic and can ionize into ammonium and chloride ions. As a strong electrolyte solution, it is corrosive to most metals; compared to an aqueous solution of NH4F, it has stronger corrosive properties, and Cl... - It has stronger penetrating power and can penetrate the oxide layer on the metal surface more quickly, reacting with the metal to form soluble compounds, causing changes in the metal surface structure and corrosion of the metal.

[0013] This invention opens the door to large-scale industrial water electrolysis and provides new possibilities for the large-scale production and preparation of electrocatalytic reaction electrodes for long-term use. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the technical route and working principle of the present invention;

[0015] Figure 2 Low-magnification SEM image of the surface of the multi-scale porous electrode prepared for Experiment 1;

[0016] Figure 3 High-magnification SEM image of the surface of the multi-scale porous electrode prepared for Experiment 1. Detailed Implementation

[0017] Specific Implementation Method 1: This implementation method is a method for preparing a multi-scale porous electrode with high activity and high conductivity, specifically carried out according to the following steps:

[0018] I. Fabrication of micron-scale porous electrode support structures using selective laser melting 3D printing technology;

[0019] 2. The porous electrode support structure prepared in step 1 is placed into an electrolyte solution to carry out a constant voltage electrochemical activation process to modify the surface of the electrode material and obtain a nanoscale micro-rough surface morphology. Then the electrode is washed multiple times in deionized water solution and finally dried to obtain a multi-scale porous electrode.

[0020] The electrolyte solution is an aqueous solution of ammonium chloride.

[0021] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the material of the micron-scale porous electrode support structure described in step one is a Ti-based alloy, Au, Ag, or Cu. Everything else is the same as in Specific Implementation Method One.

[0022] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the selective laser melting 3D printing technology in step one is combined with modeling software to model a micron-level porous structure, and then the subsequent printing process is carried out to prepare the required micron-level porous electrode structure. The micron-level pore structure can be a porous lattice structure with a regular configuration, or it can be a porous structure with an irregular minimal curved surface. Everything else is the same as in Specific Implementation Method One or Two.

[0023] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the concentration of the ammonium chloride aqueous solution in step two is 0.2 mol / L to 0.8 mol / L. Everything else is the same as in Specific Implementation Methods One to Three.

[0024] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that, before the constant voltage electrochemical activation process in step two, the porous electrode support structure prepared in step one is first ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water, and then dried. Everything else is the same as in Specific Implementation Method Four.

[0025] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the constant-voltage electrochemical activation process in step two involves placing the porous electrode support structure in an electrolyte solution and using a three-electrode device to perform an in-situ electrochemical activation process on the porous electrode surface. Everything else is the same as in Specific Implementation Method Five.

[0026] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that: in the three-electrode device described in step two, graphite or carbon rods are used as the counter electrode, Pt is used as the reference electrode, and a porous electrode support structure is used as the working electrode. Everything else is the same as in Specific Implementation Method Six.

[0027] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that: in step two, a constant voltage of 1.38V to 1.47V is applied during the constant voltage electrochemical activation process, and the activation time is 4h to 6h. A rough nanostructure with a thickness of 1-3nm can be observed on the porous electrode support surface in step one, resulting in a multi-scale porous electrode structure. Everything else is the same as in Specific Implementation Method Seven.

[0028] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the drying temperature in step two is 60℃~100℃. Everything else is the same as in Specific Implementation Method Eight.

[0029] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the drying time in step two is 2 hours. Everything else is the same as in Specific Implementation Method Nine.

[0030] The invention was verified using the following experiments:

[0031] Experiment 1: This experiment demonstrates a method for preparing a multi-scale porous electrode with high activity and high conductivity, specifically carried out according to the following steps:

[0032] I. Fabrication of micron-scale porous electrode support structures using selective laser melting 3D printing technology;

[0033] The micron-scale porous electrode support structure is made of 316L stainless steel.

[0034] Selective laser melting 3D printing technology combines modeling software to model micron-scale porous structures, and then performs a subsequent printing process to prepare the required micron-scale porous electrode structure.

[0035] 2. The porous electrode support structure prepared in step 1 was ultrasonically cleaned in anhydrous ethanol, acetone and deionized water respectively, and then dried. Then it was placed in an electrolyte solution for constant voltage electrochemical activation process to modify the surface of the electrode material and obtain a nanoscale micro-rough surface morphology. Then the electrode was cleaned in deionized water solution multiple times and finally dried at 80℃ for 2h to obtain a multi-scale porous electrode.

[0036] The electrolyte solution is an aqueous solution of ammonium chloride, and the concentration of the aqueous solution of ammonium chloride is 0.5 mol / L;

[0037] In step two, the constant voltage electrochemical activation process involves placing the porous electrode support structure in an electrolyte solution and using a three-electrode device to perform in-situ electrochemical activation on the surface of the porous electrode. In the three-electrode device, graphite is selected as the counter electrode, Pt as the reference electrode, and the porous electrode support structure as the working electrode.

[0038] In step two, a constant voltage of 1.4V is applied to the constant voltage electrochemical activation process, and the activation time is 5 hours.

[0039] Figure 2 Low-magnification SEM image of the surface of the multi-scale porous electrode prepared for Experiment 1. Figure 3 The image shows a high-magnification SEM image of the multi-scale porous electrode surface prepared for Experiment 1. The image reveals that in-situ electrochemical activation in the NH4Cl electrolyte solution resulted in the formation of a dense, nanoscale rough structure on the electrode surface, and the porous electrode support structure possessed a large surface area. This is significant for preparing an effectively activated electrolyte solution. The top region of the activated electrode layer is a porous structure with a dense interface and no visible defects, and the activated layer is firmly bonded to the 3D-printed scaffold. The NH4Cl solution not only facilitates surface roughening of the electrode structure but also significantly increases the activated surface area, leading to higher current density and higher activity during the reaction.

[0040] Experiment 2: Electrochemical tests were performed on the multi-scale porous electrode prepared in Experiment 1, with a scan rate of 0.2 mV / s. -1 With iR compensation of 85%, and an applied voltage of 1.2V–1.6V, the electrochemically activated multi-scale porous electrode can reach a maximum speed of nearly 350 mA / cm². -2 The current density.

[0041] The study investigated the current density during the reaction process, corresponding to current densities of 10–50 mA / cm². -2 The overpotential conditions were investigated, and it was found that the current density of the multi-scale porous electrode obtained in Experiment 1 increased and the reaction overpotential decreased. In-situ electrochemical activation enhanced the OER reaction activity.

[0042] The multi-scale porous electrode prepared in Experiment 1 exhibits extremely high current density under ultra-low overpotential conditions during the OER reaction. The high current density achieved in this invention reaches 1.4 A·cm. -2 ~1.6A·cm -2 The overpotential is 290mV to 300mV.

[0043] Achieving stability under high current density: The multi-scale porous electrode prepared in Experiment 1 was found to maintain a high current density (1.4 A·cm⁻¹) for nearly 50 hours during OER catalysis. -2 ~1.6A·cm -2 The electrode is in a stable working state with no significant fluctuations in its working potential. Furthermore, after high-current, long-term electrocatalytic testing, SEM observation showed no significant changes in the nanoscale morphology of the electrode surface, nor in the electrode composition and chemical state.

Claims

1. A method for preparing a multi-scale porous electrode with high activity and high conductivity, characterized in that... The preparation method of a multi-scale porous electrode with high activity and high conductivity is carried out according to the following steps: I. Fabrication of micron-scale porous electrode support structures using selective laser melting 3D printing technology; The micron-scale porous electrode support structure is made of Ti-based alloy, Au, Ag, or Cu.

2. The porous electrode support structure prepared in step 1 is placed into an electrolyte solution to carry out a constant voltage electrochemical activation process to modify the surface of the electrode material and obtain a nanoscale micro-rough surface morphology. Then the electrode is washed multiple times in deionized water solution and finally dried to obtain a multi-scale porous electrode. The electrolyte solution is an aqueous solution of ammonium chloride; The concentration of the ammonium chloride aqueous solution is 0.2 mol / L to 0.8 mol / L.

2. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 1, characterized in that... In step one, selective laser melting 3D printing technology combines modeling software to create micron-scale porous structures, and then proceeds with the subsequent printing process to prepare the required micron-scale porous electrode structure.

3. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 1, characterized in that... In step two, before the constant voltage electrochemical activation process, the porous electrode support structure prepared in step one is first ultrasonically cleaned in anhydrous ethanol, acetone and deionized water respectively, and then dried.

4. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 1, characterized in that... In step two, the constant-voltage electrochemical activation process involves placing the porous electrode support structure in an electrolyte solution and using a three-electrode device to perform in-situ electrochemical activation of the porous electrode surface.

5. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 4, characterized in that... In the three-electrode device described in step two, graphite or carbon rods are selected as the counter electrode, Pt is selected as the reference electrode, and a porous electrode support structure is selected as the working electrode.

6. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 5, characterized in that... In step two, a constant voltage of 1.38V to 1.47V is applied during the constant voltage electrochemical activation process, and the activation time is 4h to 6h.

7. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 1, characterized in that... The drying temperature in step two is 60℃~100℃.

8. The method for preparing a multi-scale porous electrode with high activity and high conductivity according to claim 7, characterized in that... The drying time in step two is 2 hours.

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