A bimetallic coordinated polypyrrole / graphene oxide composite nanosheet, its preparation method, and its application in supercapacitors.

Abstract

This invention discloses a bimetallic coordinated polypyrrole / graphene oxide composite nanosheet, its preparation method, and its application in supercapacitors. The composite nanosheet is composed of two Co... 2+ Ru 3+ Co is formed by in-situ growth of polypyrrole / graphene oxide surface modified with the same ligand by transition metal ions coordinated with 2-methylimidazolium. 2+ -Ru 3+ / (2-MeIm)x@PPy / GO nanosheets. Based on Co 2+ -Ru 3+ / (2-MeIm) x The modified electrode using PPy / GO nanosheets, due to its unique layered structure and uniform metal loading, possesses a large specific surface area and high conductivity, thus improving the device stability of supercapacitors. When applied to supercapacitors, it exhibits excellent electrochemical energy storage effects, such as high specific capacitance and stable cycling performance, showing promising application prospects in the field of energy storage devices.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitors. It discloses a bimetallic coordinated polypyrrole / graphene oxide composite nanosheet, its preparation method, and its application in supercapacitors. Background Technology

[0002] Supercapacitors, as a novel type of energy storage device, have broad application prospects in the field of energy storage due to their advantages such as high safety, high power density, fast charging and discharging speed, and long cycle life. In supercapacitor research, electrode materials are the main factor determining the performance of supercapacitors.

[0003] Electrode materials are considered a crucial component of supercapacitors. Carbon materials, metal oxides, conductive polymers, and composite materials have all been applied to electrode materials. Among them, conductive polymer electrode materials such as polypyrrole achieve energy storage through the Faraday pseudocapacitance principle. The reaction occurs in the two-dimensional or three-dimensional space of the electrode material's surface and bulk phase, enabling the conductive polymer to store high energy density charges and generate high Faraday pseudocapacitance. While conductive polymers are easy to synthesize and possess high conductivity, their high internal resistance, poor high-power discharge performance, and poor long-term cycling stability significantly limit their application in supercapacitor energy storage.

[0004] Metals can be coordinated to conductive polymers through organic ligands. By utilizing the conductivity of the metal itself, the internal resistance of the conductive polymer can be reduced. Furthermore, the crystal structure of the metal helps maintain the spatial structure of the conductive polymer and enhances its cycle stability. These advantages are of great significance for the optimization of conductive polymers in supercapacitors. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing bimetallic coordinated polypyrrole / graphene oxide composite nanosheets and their application in supercapacitors. This composite has high capacitance, ultra-long cycle life and good rate performance.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0007] A bimetallic coordinated polypyrrole / graphene oxide composite nanosheet, wherein the composite nanosheet is composed of two Co... 2+ Ru 3+ Co is formed by in-situ growth of polypyrrole / graphene oxide on the surface of a polypyrrole / graphene oxide modified with the same ligand, with transition metal ions coordinated to 2-methylimidazolium. 2+ -Ru 3+ / (2-MeIm)x@PPy / GO nanosheets.

[0008] The preparation method of the above-mentioned bimetallic coordinated polypyrrole / graphene oxide composite nanosheets includes the following steps:

[0009] 1) Pyrrole was chemically polymerized in situ onto GO nanosheets under ultrasonic radiation to obtain PPy / GO nanosheets;

[0010] 2) Under oil bath heating conditions, 2-chloromethylimidazoline hydrochloride was modified onto PPy / GO nanosheets to obtain 2-MeIm / PPy / GO nanosheets;

[0011] 3) 2-MeIm / PPy / GO nanosheets and 2-methylimidazole were dispersed in methanol, and then cobalt chloride and ruthenium chloride were added sequentially. After standing, the cobalt-ruthenium bimetallic coordination compound was loaded onto the 2-MeIm / PPy / GO nanosheets to obtain a cobalt-ruthenium bimetallic complex / polypyrrole / graphene oxide (Co). 2+ -Ru 3+ / (2-MeIm) x @PPy / GO) Nanosheets.

[0012] The preparation method of the above-mentioned bimetallic coordinated polypyrrole / graphene oxide composite nanosheets, step 1) specifically involves: adding GO nanosheets to deionized water and dispersing them ultrasonically, then adding pyrrole (Py), dispersing them ultrasonically again, adding FeCl3·6H2O, continuing ultrasonication, washing, centrifugation, and vacuum drying to obtain PPy / GO nanosheets.

[0013] The above-mentioned method for preparing bimetallic coordinated polypyrrole / graphene oxide composite nanosheets uses a mass ratio of GO nanosheets:pyrrole:FeCl3·6H2O = 1:1:3.

[0014] The preparation method of the above-mentioned bimetallic coordinated polypyrrole / graphene oxide composite nanosheets, step 2) specifically involves: mixing PPy / GO nanosheets, DMF, and 2-chloromethylimidazoline hydrochloride, followed by sonication, adding KOH powder, sonication, heating for reflux reaction, cooling, washing, centrifugation, and vacuum drying to obtain 2-MeIm / PPy / GO nanosheets.

[0015] The above-mentioned method for preparing bimetallic coordinated polypyrrole / graphene oxide composite nanosheets involves a solid-liquid ratio of PPy / GO nanosheets: DMF: 2-chloromethylimidazoline hydrochloride: KOH powder = 2g: 1L: 3g: 2g, with a reflux reaction temperature of 60℃ and a reflux time of 24h.

[0016] The preparation method of the above-mentioned bimetallic coordinated polypyrrole / graphene oxide composite nanosheets, step 3) specifically involves: adding 2-MeIm / PPy / GO, methanol, and 2-methylimidazole to a container, and sonicating; adding CoCl2·6H2O, RuCl3, and methanol to another container, dissolving them, and then quickly adding the solutions to the first container; allowing the mixture to stand; washing the resulting product; centrifuging; and vacuum drying to obtain Co. 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets.

[0017] The above-mentioned method for preparing bimetallic coordinated polypyrrole / graphene oxide composite nanosheets uses a mass ratio of 2-MeIm / PPy / GO:2-methylimidazole:CoCl2.6H2O:RuCl3 = 1g:3.3g:1.2g:1.3g.

[0018] A Co-based 2+ -Ru 3+ / (2-MeIm) x The modified electrode of @PPy / GO nanosheets uses nickel foam as the substrate electrode and incorporates the Co as described in claim 1. 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets are attached to nickel foam to form Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO modifies the electrode.

[0019] A Co-based 2+ -Ru 3+ / (2-MeIm) x The modified electrode of @PPy / GO nanosheets includes the following steps:

[0020] 1) Take the above Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets, acetylene black and polytetrafluoroethylene were ultrasonically dispersed in 1 ml of anhydrous ethanol to obtain a uniformly dispersed composite modifier.

[0021] 2) The uniformly dispersed composite modifier was drop-coated onto a clean nickel foam surface, dried at room temperature, and then compressed into tablets using a tablet press to obtain Co. 2+ -Ru 3+ / (2-MeIm) x @PPy / GO modifies the electrode.

[0022] The above-mentioned Co-based 2+ -Ru3+ / (2-MeIm) x @PPy / GO nanosheet-modified electrodes, by mass ratio, Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO: Acetylene black: Tetrafluoroethylene = 8:1:1.

[0023] The above-mentioned Co-based 2+ -Ru 3+ / (2-MeIm) x The application of @PPy / GO nanosheet-modified electrodes in the field of supercapacitors is characterized by the following method: applying the Co as described in claim 9... 2+ -Ru 3+ / (2-MeIm) x A three-electrode system was formed, consisting of a PPy / GO modified electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode, and a supercapacitor was prepared in 2M potassium hydroxide solution.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] 1. The modified electrode prepared in this invention combines graphene oxide and polypyrrole to form relatively stable nanosheets, essentially retaining the advantages of both materials while also optimizing performance in the capacitor aspect. The prepared cobalt-ruthenium bimetallic coordination conductive polymer simultaneously possesses the characteristics of high conductivity, high capacitance, and high cycling stability of conductive polymers.

[0026] 2. The nanosheets described in this invention have a uniform layered structure. During rapid charging and discharging, the bimetallic complex / polypyrrole / graphene oxide composite nanosheets show little change and have a stable molecular structure. The coordination of the bimetal improves the defects in the properties caused by the composite of conductive polymers and carbon-based materials, and improves the stability and other related properties of the material.

[0027] 3. Compared with the prior art, the transition metal ion coordinated conductive polymer designed and synthesized in this invention has higher conductivity and structural stability, which effectively improves the related performance of composite nanosheet electrode materials in terms of capacitance, rate performance and cycle stability. Attached Figure Description

[0028] Figure 1 For Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheet scanning electron microscope (SEM) images;

[0029] Figure 2 For Co2+ -Ru 3+ / (2-MeIm) x EDS image of @PPy / GO nanosheets.

[0030] Figure 3 For Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets and energy scattering X-ray spectra (XRD) of PPy / GO nanosheets.

[0031] Figure 4 For Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO modified electrode galvanostatic charge-discharge (GCD) curves at different current densities.

[0032] Figure 5 For Co 2+ -Ru 3+ / (2-MeIm) x Cyclic voltammetry (CV) curves of the @PPy / GO modified electrode at different scan rates.

[0033] Figure 6 For Co 2+ -Ru 3+ / (2-MeIm) x Stability curve of the @PPy / GO modified electrode after 10,000 cycles at a current density of 10 A / g. Detailed Implementation

[0034] The following detailed embodiments further illustrate the present invention. 2+ -Ru 3+ / (2-MeIm) x The specific experimental process for preparing @PPy / GO nanosheets is as follows:

[0035] Example 1: Co 2+ -Ru 3+ The preparation method of / (2-MeIm)x@PPy / GO nanosheets (I) is as follows:

[0036] 1) Preparation of GO nanosheets: 67.5 mL of concentrated sulfuric acid, 2.0 g of high-purity graphite, and 1.6 g of NaNO3 were added to a three-necked flask and stirred until homogeneous. The system temperature was kept below 5 °C. 9 g of KMnO4 was slowly and continuously added to the mixed solution over one hour, and then the mixture was placed in a 36 °C water bath for 0.5 h. After standing at room temperature for two weeks, the solution was diluted with 560 mL of 60 °C water, and H2O2 was added dropwise until the solution turned bright yellow. The solution was then centrifuged while hot (rpm = 10000), washed until neutral, and then vacuum dried at 50 °C to obtain GO nanosheets.

[0037] 2) PPy / GO nanosheets: 0.1g of GO nanosheets were added to 50mL of deionized water and ultrasonically dispersed. Then, 0.1g of pyrrole (Py) was added and ultrasonically dispersed again. 0.6g of FeCl3·6H2O was added and ultrasonication was continued for 0.5h. The resulting product was washed with distilled water and ethanol in sequence, centrifuged (rmp=10000, t=300s), and vacuum dried at 50℃ to obtain PPy / GO nanosheets.

[0038] 3) 2-MeIm / PPy / GO nanosheets: In a 100ml round-bottom flask, add 0.1g of PPy / GO, 50ml of DMF, and 0.15g of 2-chloromethylimidazoline hydrochloride. Sonicate for 5 min, then add 0.1g of KOH powder and sonicate for another 5 min. React under reflux at 60℃ for 24 hours in an oil bath. After cooling, wash the product sequentially with distilled water and ethanol, centrifuge (rpm = 10000, t = 300s), and vacuum dry at 50℃ to obtain 2-MeIm / PPy / GO nanosheets.

[0039] 4) Co 2+ -Ru 3+ / (2-MeIm) x Preparation of @PPy / GO nanosheets: In a 150ml Erlenmeyer flask with a stopper, add 0.02g of 2-MeIm / PPy / GO, 30ml of methanol, and 0.066g of 2-methylimidazole. Sonicate for 5 min. In another Erlenmeyer flask with a stopper, add 0.024g of CoCl2·6H2O, 0.026g of RuCl3·3H2O, and 10ml of methanol. After dissolving, quickly add the dissolved product to the first Erlenmeyer flask. Let stand at 25℃ for 24 hours. Wash the obtained product sequentially with distilled water and ethanol, centrifuge (rpm = 10000, t = 300s), and vacuum dry at 50℃ to obtain Co. 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets.

[0040] (II) Testing

[0041] 1. Co 2+ -Ru3+ / (2-MeIm) x Electron microscopy image of @PPy / GO nanosheets as shown below Figure 1 As shown, scanning electron microscopy (SEM) images reveal that the prepared material exhibits a unique sheet-like and layered structure, with metal effectively loaded into the nanosheet material.

[0042] 2. Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets EDS such as Figure 2 As shown, based on the peak values, it can be analyzed that various elements are located on the polypyrrole / graphene oxide nanosheets.

[0043] 3. Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets and their energy scattering X-ray (XRD) spectra are shown below. Figure 3 As shown, comparing the two materials, there are no obvious metallic peaks, and through... Figure 2 It can be seen that the cobalt-ruthenium bimetal is effectively coordinated onto polypyrrole / graphene oxide via 2-methylimidazole and is coated by polypyrrole / graphene oxide.

[0044] Example 2 based on Co 2+ -Ru 3+ / (2-MeIm) x The preparation method of the modified electrode of @PPy / GO nanosheet (I) is as follows:

[0045] 1) Take 8 mg of the dried Co prepared in Example 1 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets were mixed with 1 mg of acetylene black, 1 mg of polytetrafluoroethylene and 1 ml of anhydrous ethanol and ultrasonically dispersed for 30 min to obtain a black suspension with a concentration of 8 mg / mL, which is the composite modifier, for later use.

[0046] 2) Electrode treatment: Cut the nickel foam into 1cm×1.5cm pieces, sonicate them for 30min each with 6M hydrochloric acid, anhydrous ethanol and water, and then dry them for later use.

[0047] 3) Preparation of modified electrode: Use a pipette to transfer 0.125 ml of the composite modifier prepared in step 1), drop it onto a clean nickel foam surface, let it air dry at room temperature, and then compress it into tablets using a tablet press.

[0048] (II) Electrochemical Performance Testing

[0049] 1. Co2+ -Ru 3+ / (2-MeIm) x Study on charge-discharge performance of @PPy / GO nanosheet modified electrodes

[0050] With Co 2+ -Ru 3+ / (2-MeIm) x The PPy / GO nanosheet modified electrode was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum sheet electrode as the auxiliary electrode. The experiment was conducted on a CHI760E electrochemical workstation, including the acquisition and processing of experimental data. Charge-discharge tests were performed in 2M KOH solution at current densities of 50 A / g, 30 A / g, 20 A / g, 10 A / g, 5 A / g, 3 A / g, 2 A / g, and 1 A / g.

[0051] Figure 4 For Co 2+ -Ru 3+ / (2-MeIm) x The GCD curves of the @PPy / GO nanosheet modified electrode at different scan rates show that the maximum capacity is 321.8 F / g at a scan rate of 1 A / g, and the charge-discharge curves have a certain degree of symmetry, indicating that the material has a certain degree of reversibility during constant current charge-discharge.

[0052] 2. Co 2+ -Ru 3+ (2-MeIm) x Comparison of cyclic voltammetry curves of @PPy / GO nanosheet modified electrodes

[0053] Method: In an electrolytic cell with 2M KOH solution, Co... 2+ -Ru 3+ / (2-MeIm) x The modified electrode of @PPy / GO nanosheets was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum sheet electrode as the auxiliary electrode. The experiment was carried out on a CHI760E electrochemical workstation, and its attached computer software was used for data acquisition and processing. Cyclic voltammetry was performed in the potential range of 0V to -0.6V (vs. RHE), and stable cyclic voltammograms were recorded.

[0054] like Figure 5 As shown, Co 2+ -Ru 3+ / (2-MeIm) x The cyclic voltammetry (CV) comparison of the @PPy / GO nanosheet modified electrode shows obvious redox peaks, indicating good Faraday pseudocapacitance, as well as good material stability and rate performance.

[0055] 3. Measurement of nanosheet stability

[0056] With Co 2+ -Ru 3+ / (2-MeIm) x The PPy / GO nanosheet modified electrode was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum sheet electrode as the auxiliary electrode. The experiment was conducted on a CHI760E electrochemical workstation, including the acquisition and processing of experimental data. The experiment was performed in 2M KOH solution for 10,000 charge-discharge cycles at a rate of 10 A / g.

[0057] Figure 6 For Co 2+ -Ru 3+ / (2-MeIm) x The capacitance decay curve of the @PPy / GO nanosheet modified electrode after 10,000 cycles at a scan rate of 10 A / g shows that the capacitance can still be maintained at 100% after 10,000 constant current charge-discharge cycles.

[0058] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalent alterations can be made within the spirit and scope defined by the claims of the present invention, but all such changes will fall within the protection scope of the present invention.

Claims

1. A Co-based 2+ -Ru 3+ / (2-MeIm) x The modified electrode of @PPy / GO nanosheets is characterized by, Using nickel foam as the base electrode, Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets are attached to nickel foam to form Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO modified electrodes; The Co 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets are made of two types of Co 2+ Ru 3+ Co is formed by the in-situ growth of transition metal ions coordinated with 2-methylimidazol on the surface of polypyrrole / graphene oxide modified with the same ligand. 2+ -Ru 3+ / (2-MeIm)x@PPy / GO nanosheets; The preparation method includes the following steps: 1) Pyrrole was chemically polymerized in situ onto GO nanosheets under ultrasonic radiation to obtain PPy / GO nanosheets; 2) Under oil bath heating conditions, 2-chloromethylimidazoline hydrochloride was modified onto PPy / GO nanosheets to obtain 2-MeIm / PPy / GO nanosheets; 3) 2-MeIm / PPy / GO nanosheets and 2-methylimidazole were dispersed in methanol, and then cobalt chloride and ruthenium chloride were added sequentially. After standing, the cobalt-ruthenium bimetallic coordination compound was loaded onto the 2-MeIm / PPy / GO nanosheets to obtain a cobalt-ruthenium bimetallic complex / polypyrrole / graphene oxide (Co). 2+ -Ru 3+ / (2-MeIm) x (@PPy / GO) Nanosheets; Step 1) Specifically: Add GO nanosheets to deionized water and disperse them by ultrasonication, then add pyrrole (Py), disperse by ultrasonication again, add FeCl3·6H2O, continue ultrasonication, wash, centrifuge, and vacuum dry to obtain PPy / GO nanosheets. By mass ratio, GO nanosheets:pyrrole:FeCl3·6H2O = 1:1:3; Step 2) Specifically, PPy / GO nanosheets, DMF, and 2-chloromethylimidazoline hydrochloride are mixed and sonicated. KOH powder is added, and the mixture is sonicated and heated under reflux. After cooling, the mixture is washed, centrifuged, and vacuum dried to obtain 2-MeIm / PPy / GO nanosheets. The solid-liquid ratio was PPy / GO nanosheets: DMF: 2-chloromethylimidazoline hydrochloride: KOH powder = 2g: 1L: 3g: 2g. The reflux reaction temperature was 60℃ and the reflux time was 24h. Step 3) specifically involves: adding 2-MeIm / PPy / GO, methanol, and 2-methylimidazole to a container, and sonicating. Separately, add CoCl2·6H2O, RuCl3, and methanol to another container, dissolve them, and quickly add the dissolved substances to the first container. Allow the mixture to stand, wash the resulting product, centrifuge, and vacuum dry to obtain Co. 2+ -Ru 3+ / (2-MeIm) x @PPy / GO nanosheets; By mass ratio, 2-MeIm / PPy / GO: 2-methylimidazole: CoCl2.6H2O: RuCl3 = 1g: 3.3g: 1.2g: 1.3g.

2. The Co-based method according to claim 1 2+ -Ru 3+ / (2-MeIm) x The application of PPy / GO nanosheet-modified electrodes in the field of supercapacitors is characterized by, The method is as follows: The Co described in claim 1... 2+ -Ru 3+ / (2-MeIm) x A three-electrode system was formed, consisting of a PPy / GO modified electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode, and a supercapacitor was prepared in 2 M potassium hydroxide solution.

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