A pb(ii) coordination polymer catalytic electrode and a preparation method and application thereof

Abstract

This invention discloses a Pb(II) coordination polymer catalytic electrode, its preparation method, and its application, belonging to the field of flow battery electrode materials and electrochemical energy storage technology. The catalytic electrode uses an acid-washed carbon felt electrode as a substrate, and nanoscale Pb-based polymers are grown in situ on the surface of the carbon felt substrate via ultrasonic chemical deposition. 2+ A polymer catalyst layer formed by coordination polymerization with nitrogen-containing organic ligands. The preparation method involves acid washing pretreatment of the original carbon felt electrode, mixing lead source solution and iodine source solution under ultrasonic conditions to obtain a lead-containing intermediate reaction system, then placing the acid-washed carbon felt electrode in the lead-containing intermediate reaction system, adding a nitrogen-containing organic ligand solution, and then in-situ polymerizing the Pb(II) metal-organic coordination polymer on the carbon felt fiber surface under ultrasonic conditions. This catalyst electrode can improve the effective active area and mass transfer accessibility of the electrode, maintain good structural stability under acidic conditions, and enhance the coulombic efficiency and long-term cycling stability of iron-chromium redox flow batteries.

Description

Technical Field

[0001] This invention belongs to the field of flow battery electrode materials and electrochemical energy storage technology, specifically relating to a Pb(II) coordination polymer catalytic electrode, its preparation method, and its application. Background Technology

[0002] Iron-chromium flow batteries use Fe 2+ / Fe 3+ With Cr 3+ / Cr 2+ As an electrochemically active material, it typically uses a hydrochloric acid system as the supporting electrolyte, offering advantages such as low cost and abundant resources. However, the negative electrode Cr in existing iron-chromium redox flow batteries... 3+ / Cr 2+ The reaction kinetics are relatively slow, and under acidic conditions, the negative electrode potential is close to the hydrogen evolution reaction potential. During charging, hydrogen evolution side reactions are prone to occur, leading to problems such as decreased coulombic efficiency, capacity decay, increased polarization, and electrode / electrolyte imbalance.

[0003] To improve Cr 3+ / Cr 2+ To improve reaction kinetics and suppress hydrogen evolution side reactions, existing technologies have proposed various electrode modification strategies. For example, some schemes introduce noble metal or lead catalyst layers onto inert substrates (such as carbon felt, graphite felt, etc.), or add lead (Pb) or bismuth (Bi) metal salts to the electrolyte, allowing them to deposit in situ during operation to form an active layer, thereby increasing the negative electrode reaction rate and raising the hydrogen evolution overpotential. Other schemes involve electroplating lead or bismuth onto carbon felt, or obtaining a metal nanoparticle layer through oxide coating followed by electrochemical reduction, aiming to improve the negative electrode interface reaction. While the aforementioned strategies can mitigate negative electrode polarization and hydrogen evolution side reactions under certain conditions, they generally suffer from the following shortcomings: First, when relying on electrodeposition / electroplating or electrochemical reduction steps, the formation and distribution of the catalyst layer are often sensitive to current density, time, local mass transfer, and pore structure, easily leading to uneven spatial distribution, insufficient adhesion of the active layer, or redistribution problems caused by dissolution-redeposition during cycling. Second, some solutions have long process chains, involving multiple coating, reduction, and cleaning processes, which limits repeatability and scalability. Third, the stability, durability, and bonding strength with the carbon-based framework of existing metal or metal nanoparticle catalyst layers in acidic flowing electrolytes and long-term shear scouring environments still need further improvement.

[0004] Therefore, there is an urgent need for a negative electrode material and its preparation method that can achieve uniform loading and strong bonding of catalytic components on porous carbon-based electrodes such as carbon felt, with acid resistance and a simplified preparation process, thereby improving the performance of Cr. 3+ / Cr 2+Simultaneously suppressing hydrogen evolution side reactions through reaction kinetics further improves the coulombic efficiency, energy efficiency, and long-term cycle stability of the iron-chromium flow battery. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a Pb(II) coordination polymer catalytic electrode and its preparation method, and to use it as the negative electrode Cr in an iron-chromium flow battery. 3+ / Cr 2+ The reaction involves a simple process to uniformly nanoload and tightly bond a Pb(II) coordination polymer catalyst layer on the surface of carbon felt fiber, thereby improving the kinetics of chromium ion redox reaction and suppressing hydrogen evolution side reaction.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a Pb(II) coordination polymer catalytic electrode, which uses an acid-washed carbon felt electrode as a substrate and grows a nanoscale Pb(II) metal-organic coordination polymer catalytic layer in situ on the surface of the carbon felt substrate by ultrasonic chemical deposition.

[0008] Furthermore, Pb(II) metal-organic coordination polymers are composed of Pb 2+ It is formed by coordination polymerization with nitrogen-containing organic ligands.

[0009] Secondly, the present invention provides a method for preparing a Pb(II) coordination polymer catalytic electrode, comprising the following steps:

[0010] Carbon felt pretreatment: The raw carbon felt electrode is immersed in an acid solution to remove impurities, then washed clean and dried to obtain an acid-washed carbon felt electrode.

[0011] Precursor solution preparation: Mix lead source solution and iodine source solution and react under probe ultrasound conditions to obtain a lead-containing intermediate reaction system;

[0012] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode is placed in a lead-containing intermediate reaction system and a nitrogen-containing organic ligand solution is added. The reaction continues under the ultrasonic conditions of the probe, so that the Pb(II) metal-organic coordination polymer is polymerized in-situ on the surface of the carbon felt fiber and uniformly loaded.

[0013] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed and dried to obtain the Pb(II) coordination polymer catalytic electrode.

[0014] Furthermore, in the carbon felt pretreatment, the acid solution is hydrochloric acid and / or sulfuric acid solution with a concentration of 1M-6M, the soaking time is 2h-24h, the washing is done with deionized water, the drying temperature is 60℃-100℃, and the drying time is 6h-12h.

[0015] Furthermore, in the preparation of the precursor solution, the lead source is one or more of lead acetate, lead nitrate, lead perchlorate, and lead chloride; the iodine source is one or more of potassium iodide, sodium iodide, and lithium iodide.

[0016] The concentration of the lead source solution is 0.5M-1M, the concentration of the iodine source solution is 0.5M-1M, and the volume ratio of the lead source solution to the iodine source solution is 1:1.

[0017] Furthermore, in the preparation of the precursor solution, the ultrasound probe uses a high-density probe with a working frequency of 20kHz-100kHz, an output power of 100W-1000W, and a reaction time of 2h-10h.

[0018] Furthermore, in the in-situ ultrasonic polymerization, the nitrogen-containing organic ligand is one or more of pyrazine, pyrimidine, and pyridine; the concentration of the nitrogen-containing organic ligand solution is 0.5M-1M, and the volume ratio of the nitrogen-containing organic ligand solution to the lead-containing intermediate reaction system is 1:1.

[0019] Furthermore, in in-situ ultrasonic polymerization, the probe uses a high-density probe with a working frequency of 10kHz-40kHz, an output power of 50W-500W, and a response time of 6h-48h.

[0020] Furthermore, in the post-treatment, acetone and ether are used for washing, with a washing time of 6h-48h, and the drying temperature is 60℃-80℃, with a drying time of 12h-24h.

[0021] Thirdly, the present invention provides an application of a Pb(II) coordination polymer catalytic electrode as a negative electrode in an iron-chromium flow battery.

[0022] Compared with existing lead-based catalysts (such as metallic lead, lead dioxide, and their electrodeposited layers) on the negative electrode side of iron-chromium flow batteries and conventional coating, electroplating, or electrodeposition modification methods, the present invention has at least the following beneficial effects:

[0023] 1. This invention employs an ultrasonic chemical-induced instantaneous nucleation and rapid growth mechanism, which enables in-situ construction of nanoscale catalytic phases within the three-dimensional fiber skeleton and pores of carbon felt. This allows the catalytic components to cover the active interface more uniformly and fully at the microscale, significantly reducing the local agglomeration, uneven distribution, and "surface deposition" problems commonly found in traditional methods, thereby improving the effective active area and mass transfer accessibility of the electrode.

[0024] 2. The Pb(II) coordination polymer of the present invention has a coordination crosslinking structure, which can maintain good structural stability in an acidic electrolyte environment; at the same time, it is tightly bonded to the carbon felt fiber, which is beneficial to improve the erosion resistance and cycle durability of the catalyst layer, reduce the risk of shedding, dissolution or redistribution during long-term operation, and thus slow down capacity decay and performance drift.

[0025] 3. Based on the uniform loading and stable interface of Pb(II) coordination polymer on a carbon felt matrix, this catalytic electrode can effectively promote the growth of Cr on the negative electrode. 3+ / Cr 2+ The electrochemical reaction kinetics of the redox couple reduce charge transfer impedance and polarization, thereby improving battery voltage efficiency and energy efficiency, and enhancing rate performance.

[0026] 4. In the acidic system of iron-chromium redox flow batteries, the hydrogen evolution side reaction at the negative electrode is a significant cause of decreased coulombic efficiency and electrolyte imbalance. This invention, by constructing a stable and uniform lead coordination polymer catalytic interface, can reduce the overpotential of the Cr reaction while suppressing the tendency of hydrogen evolution, thereby reducing the loss of active material and electrolyte composition shift caused by gas evolution, and thus improving coulombic efficiency and long-term cycle stability.

[0027] 5. The preparation process of this invention is simple and highly controllable, suitable for large-area processing of porous carbon-based electrodes, and easy to scale up. By adjusting the ultrasonic parameters and precursor system, the loading and morphology of the catalyst layer can be controlled, further improving product consistency and engineering adaptability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process flow for preparing the Pb(II) coordination polymer catalytic electrode in Example 1;

[0029] Figure 2 The image shows a scanning electron microscope (SEM) image of the Pb(II) coordination polymer catalytic electrode prepared in Example 1.

[0030] Figure 3 This is the cyclic voltammetry (CV) diagram from the electrochemical tests in Example 1;

[0031] Figure 4 This is the electrochemical impedance spectroscopy (EIS) spectrum from the electrochemical test in Example 1;

[0032] Figure 5 This is a schematic diagram of the Pb(II) coordination polymer catalytic electrode assembled with an iron-chromium redox flow cell in Example 1.

[0033] Figure 6 The rate performance diagram of the iron-chromium flow battery assembled with the Pb(II) coordination polymer catalytic electrode in Example 1 is shown. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0035] A Pb(II) coordination polymer catalytic electrode is prepared by using an acid-washed carbon felt electrode as a substrate, and growing Pb-based polymers in situ on the surface of the carbon felt substrate via ultrasonic chemical deposition. 2+ Nanoscale Pb(II) metal-organic coordination polymer catalyst layer formed by coordination polymerization with nitrogen-containing organic ligands.

[0036] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0037] Carbon felt pretreatment: The raw carbon felt electrode is placed in a 1M-6M hydrochloric acid and / or sulfuric acid solution and soaked for 2h-24h to remove impurities. Then it is washed with deionized water and dried at 60℃ for 12h to obtain an acid-washed carbon felt electrode.

[0038] Precursor solution preparation: Mix lead source solution and iodine source solution, place in a high-density probe, and react for 2-10 hours at a working frequency of 20kHz-100kHz and an output power of 100W-1000W to obtain a lead-containing intermediate reaction system; the lead source is one or more of lead acetate, lead nitrate, lead perchlorate, and lead chloride; the iodine source is one or more of potassium iodide, sodium iodide, and lithium iodide; the concentration of the lead source solution is 0.5M-1M, the concentration of the iodine source solution is 0.5M-1M, and the volume ratio of the lead source solution to the iodine source solution is 1:1.

[0039] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode is placed in a lead-containing intermediate reaction system and a nitrogen-containing organic ligand solution is added. Ultrasonic polymerization is continued at a working frequency of 10kHz-40kHz and an output power of 50W-500W for 6h-48h in-situ reaction, so that the Pb(II) metal-organic coordination polymer is polymerized in-situ on the surface of the carbon felt fiber and uniformly loaded.

[0040] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 6-48 hours, and dried at 80°C for 12 hours to obtain the Pb(II) coordination polymer catalytic electrode.

[0041] Application of a Pb(II) coordination polymer catalytic electrode as a negative electrode in an iron-chromium flow battery.

[0042] Example 1

[0043] A Pb(II) coordination polymer catalytic electrode is prepared by using an acid-washed carbon felt electrode as a substrate, and growing Pb-based polymers in situ on the surface of the carbon felt substrate via ultrasonic chemical deposition. 2+ Nanoscale Pb(II) metal-organic coordination polymer catalyst layer formed by coordination polymerization with nitrogen-containing organic ligands.

[0044] A method for preparing a Pb(II) coordination polymer catalytic electrode, such as Figure 1 The flowchart shown includes the following steps:

[0045] Carbon felt pretreatment: The original carbon felt electrode was placed in a 3M sulfuric acid solution and soaked for 6 hours. Then it was rinsed with deionized water and dried at 60°C for 12 hours to obtain an acid-washed carbon felt electrode.

[0046] Preparation of precursor solution: Place 20 mL of 0.5 M lead acetate solution and 20 mL of 0.5 M potassium iodide solution in a high-density ultrasonic probe and react for 2 h at a working frequency of 20 kHz and an output power of 600 W.

[0047] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system and 20 mL of 0.5 M pyrazine solution was added. Ultrasonic polymerization was continued at a working frequency of 20 kHz and an output power of 100 W for 12 h in situ to allow the Pb(II) metal-organic coordination polymer to be polymerized in situ and uniformly loaded on the surface of the carbon felt fiber.

[0048] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 12 h, and dried at 60 °C for 12 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0049] Performance testing:

[0050] Morphological characterization: The morphology of the Pb(II) coordination polymer catalytic electrode prepared in Example 1 was characterized using scanning electron microscopy. The results are as follows: Figure 2 As shown, the composite carbon felt electrode surface is loaded with Pb(II) coordination polymers with distinct nanosheet morphology, confirming that this preparation method can successfully construct Pb(II) coordination polymer nanosheet structures on the carbon felt surface. This dense Pb(II) coordination polymer layer significantly increases the active specific surface area of ​​the carbon felt electrode, thereby effectively enhancing its resistance to Cr. 2+ / Cr 3+ Electrochemical reactivity of the redox couple.

[0051] Electrochemical testing: A three-electrode system was used, with the working electrode being the prepared Pb(II) coordination polymer catalytic electrode, the counter electrode being a platinum sheet, and the reference electrode being a saturated calomel electrode; the electrolyte contained 0.1 M Cr 3+ A mixed solution of 3 mol / L HCl was prepared. Using the original carbon felt as a control group, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed on the prepared electrode and the original carbon felt. The results are as follows: Figure 3 and Figure 4As shown, compared with the unmodified carbon felt, the carbon felt electrode loaded with Pb(II) coordination polymer prepared by the method of the present invention exhibits higher electrochemical activity and lower charge transfer resistance, indicating that it has faster reaction kinetics. This fully demonstrates that the Pb(II) coordination polymer prepared by the present invention has excellent catalytic performance for the Cr²⁺ / Cr³⁺ redox couple reaction.

[0052] An application of a Pb(II) coordination polymer catalytic electrode as a negative electrode in an iron-chromium flow battery is described, comprising an end plate, a current collector, an electrode frame, a raw carbon felt electrode, a perfluorosulfonic acid membrane, the Pb(II) coordination polymer catalytic electrode, the electrode frame, the current collector plate, and the end plate, arranged in accordance with... Figure 5 The schematic diagram shown illustrates the assembly of a single iron-chromium redox flow battery. Both the positive and negative electrode electrolytes are 1M CrCl₃ + 1M FeCl₃ + 3M HCl, at a current of 60 mA / cm². 2 -120mA / cm 2 Constant current charge-discharge tests were conducted at a current density of 0.7V-1.2V to evaluate its rate performance. Carbon felt was used as a control group. The test results are as follows: Figure 6 As shown, compared with unmodified carbon felt, the Pb(II) coordination polymer catalytic electrode prepared by the method of the present invention can effectively improve reaction kinetics, reduce polarization and suppress hydrogen evolution side reaction, and significantly improve the energy efficiency and cycle stability of the battery while maintaining high coulombic efficiency.

[0053] Example 2

[0054] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0055] Carbon felt pretreatment: The original carbon felt electrode was placed in a 3M sulfuric acid solution and soaked for 6 hours. Then it was rinsed with deionized water and dried at 60°C for 12 hours to obtain an acid-washed carbon felt electrode.

[0056] Preparation of precursor solution: Place 20 mL of 0.5 M lead acetate solution and 20 mL of 0.5 M potassium iodide solution in a high-density ultrasonic probe and react for 2 h at a working frequency of 20 kHz and an output power of 600 W.

[0057] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system and 20 mL of 0.5 M pyridine solution was added. Ultrasonic polymerization was continued at a working frequency of 20 kHz and an output power of 100 W for 12 h in situ to allow the Pb(II) metal-organic coordination polymer to be polymerized in situ and uniformly loaded on the surface of the carbon felt fiber.

[0058] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 12 h, and dried at 60 °C for 12 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0059] Example 3

[0060] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0061] Carbon felt pretreatment: The original carbon felt electrode was placed in a 1M sulfuric acid solution and soaked for 2 hours. Then it was rinsed with deionized water and dried at 100°C for 12 hours to obtain an acid-washed carbon felt electrode.

[0062] Preparation of precursor solution: Take 20 mL of 0.8 M lead nitrate solution and 20 mL of 0.8 M potassium iodide + lithium iodide (in any ratio) mixed solution and place them in a high-density ultrasonic probe. React for 2 h at a working frequency of 40 kHz and an output power of 100 W.

[0063] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system, and 20 mL of a 0.5 M pyrimidine and pyrazine (in any ratio) mixed solution was added. Ultrasonic polymerization was continued at a working frequency of 20 kHz and an output power of 100 W for 6 h in situ, so that the Pb(II) metal-organic coordination polymer was polymerized in situ on the surface of the carbon felt fiber and uniformly loaded.

[0064] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 6 h, and dried at 60 °C for 16 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0065] Example 4

[0066] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0067] Carbon felt pretreatment: The original carbon felt electrode was placed in a 3M sulfuric acid solution and soaked for 4 hours. Then it was rinsed with deionized water and dried at 80°C for 12 hours to obtain an acid-washed carbon felt electrode.

[0068] Preparation of precursor solution: Place 20 mL of 0.8 M lead chloride solution and 20 mL of 0.8 M sodium iodide solution in a high-density ultrasonic probe and react for 2 h at a working frequency of 40 kHz and an output power of 100 W.

[0069] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system and 20 mL of 0.5 M pyrazine solution was added. Ultrasonic polymerization was continued at a working frequency of 20 kHz and an output power of 100 W for 6 h in situ to allow the Pb(II) metal-organic coordination polymer to be polymerized in situ and uniformly loaded on the surface of the carbon felt fiber.

[0070] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 6 h, and dried at 60 °C for 16 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0071] Example 5

[0072] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0073] Carbon felt pretreatment: The original carbon felt electrode was placed in a 6M hydrochloric acid solution and soaked for 4 hours. Then it was rinsed with deionized water and dried at 60°C for 6 hours to obtain an acid-washed carbon felt electrode.

[0074] Preparation of precursor solution: Take 20 mL of 0.5 M lead acetate + lead nitrate (in any ratio) mixed solution and 20 mL of 0.5 M lithium iodide solution and place them in a high-density ultrasonic probe. React for 6 h at a working frequency of 60 kHz and an output power of 1000 W.

[0075] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system, and 20 mL of 0.8 M pyridine solution was added. Ultrasonic polymerization was continued at a working frequency of 10 kHz and an output power of 50 W for 24 h in situ, so that the Pb(II) metal-organic coordination polymer was polymerized in situ on the surface of the carbon felt fiber and uniformly loaded.

[0076] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 24 h, and dried at 70 °C for 20 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0077] Example 6

[0078] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0079] Carbon felt pretreatment: The original carbon felt electrode was placed in a 6M sulfuric acid solution and soaked for 24 hours. Then it was rinsed with deionized water and dried at 60°C for 6 hours to obtain an acid-washed carbon felt electrode.

[0080] Preparation of precursor solutions: Take 20 mL of a 0.5 M lead acetate + lead perchlorate (in any ratio) mixed solution and 20 mL of a 0.5 M lithium iodide + sodium iodide (in any ratio) mixed solution and place them in a high-density ultrasonic probe. React for 6 h at a working frequency of 60 kHz and an output power of 1000 W.

[0081] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system, and 20 mL of a 0.8 M pyrimidine + pyridine (in any ratio) mixed solution was added. Ultrasonic polymerization was continued at a working frequency of 10 kHz and an output power of 500 W for 24 h in situ, so that the Pb(II) metal-organic coordination polymer was polymerized in situ on the surface of the carbon felt fiber and uniformly loaded.

[0082] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 24 h, and dried at 70 °C for 20 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0083] Example 7

[0084] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0085] Carbon felt pretreatment: The original carbon felt electrode was placed in a mixed solution of 1M hydrochloric acid and 1M sulfuric acid and soaked for 24 hours. Then it was rinsed with deionized water and dried at 60°C for 6 hours to obtain an acid-washed carbon felt electrode.

[0086] Preparation of precursor solution: Take 20 mL of 1 M lead perchlorate solution and 20 mL of 1 M lithium iodide + sodium iodide (in any ratio) mixed solution and place them in a high-density ultrasonic probe. Under the conditions of working frequency 100 kHz and output power 1000 W, react for 10 h.

[0087] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system, and 20 mL of a 1 M pyrazine + pyrimidine (in any ratio) mixed solution was added. Ultrasonic polymerization was continued at a working frequency of 40 kHz and an output power of 100 W for 48 h in situ, so that the Pb(II) metal-organic coordination polymer was polymerized in situ on the surface of the carbon felt fiber and uniformly loaded.

[0088] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 48 h, and dried at 80 °C for 24 h to obtain the Pb(II) coordination polymer catalytic electrode.

[0089] Example 8

[0090] A method for preparing a Pb(II) coordination polymer catalytic electrode includes the following steps:

[0091] Carbon felt pretreatment: The original carbon felt electrode was placed in a mixed solution of 1M hydrochloric acid and 1M sulfuric acid and soaked for 12 hours. Then it was rinsed with deionized water and dried at 100°C for 6 hours to obtain an acid-washed carbon felt electrode.

[0092] Preparation of precursor solution: Take 20 mL of 1 M lead perchlorate + lead chloride (in any ratio) mixed solution and 20 mL of 1 M sodium iodide solution and place them in a high-density ultrasonic probe. Under the conditions of working frequency 100 kHz and output power 1000 W, react for 10 h.

[0093] In-situ ultrasonic polymerization: The acid-washed carbon felt electrode was placed in a lead-containing intermediate reaction system and 20 mL of 1 M pyrazine solution was added. Ultrasonic polymerization was continued at a working frequency of 40 kHz and an output power of 100 W for 48 h in situ, so that the Pb(II) metal-organic coordination polymer was polymerized in situ on the surface of the carbon felt fiber and uniformly loaded.

[0094] Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed with acetone and diethyl ether for 48 h, and dried at 80 °C for 24 h to obtain the Pb(II) coordination polymer catalytic electrode.

Claims

1. A Pb(II) coordination polymer catalytic electrode, characterized in that, Using an acid-washed carbon felt electrode as a substrate, a nanoscale Pb(II) metal-organic coordination polymer catalytic layer was grown in situ on the surface of the carbon felt substrate by ultrasonic chemical deposition.

2. The Pb(II) coordination polymer catalytic electrode as described in claim 1, characterized in that, Pb(II) metal-organic coordination polymers are composed of Pb 2+ It is formed by coordination polymerization with nitrogen-containing organic ligands.

3. A method for preparing the Pb(II) coordination polymer catalytic electrode according to claim 1, characterized in that, Includes the following steps: Carbon felt pretreatment: The original carbon felt electrode is immersed in an acid solution, then washed clean and dried to obtain an acid-washed carbon felt electrode; Precursor solution preparation: Mix lead source solution and iodine source solution and react under probe ultrasound conditions to obtain a lead-containing intermediate reaction system; In-situ ultrasonic polymerization: The acid-washed carbon felt electrode is placed in a lead-containing intermediate reaction system and a nitrogen-containing organic ligand solution is added. The reaction continues under the ultrasonic conditions of the probe, so that the Pb(II) metal-organic coordination polymer is polymerized in-situ on the surface of the carbon felt fiber and uniformly loaded. Post-processing: The carbon felt electrode after in-situ ultrasonic polymerization was removed, washed and dried to obtain the Pb(II) coordination polymer catalytic electrode.

4. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In the carbon felt pretreatment, the acid solution is hydrochloric acid and / or sulfuric acid solution with a concentration of 1M-6M, the soaking time is 2h-24h, the washing is done with deionized water, the drying temperature is 60℃-100℃, and the drying time is 6h-12h.

5. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In preparing the precursor solution, the lead source is one or more of lead acetate, lead nitrate, lead perchlorate, and lead chloride; the iodine source is one or more of potassium iodide, sodium iodide, and lithium iodide. The concentration of the lead source solution is 0.5M-1M, the concentration of the iodine source solution is 0.5M-1M, and the volume ratio of the lead source solution to the iodine source solution is 1:

1.

6. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In the preparation of the precursor solution, the ultrasound probe uses a high-density probe with a working frequency of 20kHz-100kHz, an output power of 100W-1000W, and a reaction time of 2h-10h.

7. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In in-situ ultrasonic polymerization, the nitrogen-containing organic ligand is one or more of pyrazine, pyrimidine, and pyridine; the concentration of the nitrogen-containing organic ligand solution is 0.5M-1M, and the volume ratio of the nitrogen-containing organic ligand solution to the lead-containing intermediate reaction system is 1:

1.

8. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In in situ ultrasonic polymerization, a high-density probe is used, with a working frequency of 10kHz-40kHz, an output power of 50W-500W, and a response time of 6h-48h.

9. The method for preparing the Pb(II) coordination polymer catalytic electrode as described in claim 3, characterized in that, In the post-treatment, acetone and ether are used for washing, with a washing time of 6-48 hours. The drying temperature is 60-80℃, and the drying time is 12-24 hours.

10. The application of the Pb(II) coordination polymer catalytic electrode of claim 1 as a negative electrode in an iron-chromium flow battery.

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