阅读说明：本技术 一种PANI/Co-Fe LDHs/NF复合电极材料及其制备方法和应用 (PANI/Co-Fe LDHs/NF composite electrode material and preparation method and application thereof ) 是由 刘荣梅 孙秀伦 杨超 钱银银 沈凤翠 于 2021-06-24 设计创作，主要内容包括：本发明提供了一种PANI/Co-Fe LDHs/NF复合电极材料及其制备方法和应用,本发明采用电聚合反应制备,先制备PANI/NF复合电极,再制备PANI/Co-FeLDHs/NF复合电极材料；以PANI为载体,Co-Fe LDHs纳米片均匀地分布在PANI骨架上。与现有技术相比,本发明采用电化学方法,制备简单快捷,易重复；产品具有更优异的电催化性能,在电催化领域具有巨大的应用潜力。(The invention provides a PANI/Co-Fe LDHs/NF composite electrode material and a preparation method and application thereof, the invention adopts the preparation of electro-polymerization reaction, the PANI/NF composite electrode is firstly prepared, and then the PANI/Co-Fe LDHs/NF composite electrode material is prepared; the PANI is used as a carrier, and the Co-Fe LDHs nanosheets are uniformly distributed on the PANI framework. Compared with the prior art, the electrochemical method is adopted, so that the preparation is simple and rapid, and is easy to repeat; the product has more excellent electrocatalysis performance and has great application potential in the electrocatalysis field.)

1. A preparation method of PANI/Co-Fe LDHs/NF composite electrode material is characterized by comprising the following steps:

1) in an acid mixed solution of an aniline monomer, respectively taking a nickel foam, a saturated calomel electrode and a platinum wire as a working electrode, a reference electrode and a counter electrode, and carrying out electropolymerization reaction to obtain a PANI/NF composite electrode material;

2) and (2) performing electrochemical electrodeposition in a mixed solution of a cobalt source and an iron source by taking the PANI/NF composite electrode material prepared in the step 1) as a working electrode, a saturated calomel electrode as a reference electrode and a platinum wire as a counter electrode to obtain the PANI/Co-Fe LDHs/NF composite electrode material.

2. The method according to claim 1, wherein in step 1), the voltage of the electropolymerization reaction is 1.0 to 1.2V and the time is 2 to 6 min.

3. The production method according to claim 1 or 2, wherein the acidic mixed solution of aniline monomer in step 1) is a mixed solution of aniline and an acidic solution, and the acidic solution is a sulfuric acid solution having a concentration of 0.5 to 2.0 mol-L^-1The concentration of aniline monomer is 0.1-0.2 mol.L^-1。

4. The preparation method of claim 1, wherein the diameter of the PANI nanowire in the PANI/NF composite electrode material is 80-100 nm.

5. The method according to claim 1, wherein the cobalt source in step 2) is cobalt chloride, cobalt sulfate, cobalt acetate, or cobalt nitrate.

6. The method according to claim 1, wherein the iron source is ferrous sulfate or ferrous chloride.

7. The method as claimed in claim 1, wherein the electrodeposition voltage in step 2) is (-0.5) - (-0.7) V for 400-600 s.

8. The method according to claim 1 or 5, wherein the reaction mixture is heated to a temperature in the reaction mixtureThe concentration of the cobalt source in the mixed solution in the step 2) is 0.06-0.10 mol.L^-1(ii) a The concentration of the iron source in the mixed solution is 0.015-0.025 mol.L^-1。

9. A PANI/Co-Fe LDHs/NF composite electrode material prepared by the preparation method according to any one of claims 1 to 8, wherein Co-Fe LDHs nanosheets are uniformly distributed on a PANI skeleton grown on foamed nickel; the Co-Fe LDHs nanosheet is 50-80nm in diameter and 5-8nm in thickness.

10. The application of the PANI/Co-Fe LDHs/NF composite electrode material prepared by the preparation method of any one of claims 1 to 8 as an OER electrocatalytic material.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to a PANI/Co-Fe LDHs/NF composite electrode material as well as a preparation method and application thereof.

Background

LDHs are a typical class of two-dimensional layered electrocatalytic materials. They can be represented as [ M ]²⁺ _1-xM³⁺ _x(OH)₂][A^m-]_x/m·zH₂And O. Wherein M is²⁺And M³⁺Expressed as a metal ion having a valence of two and three, A^m-Expressed as anions for charge balance, while a large number of water molecules are present in the intercalation. The unique layered structure and the redox characteristic endow the LDHs with excellent electrocatalytic performance, but the electrochemical performance of the pure LDHs is still severely restricted by low conductivity and smaller free carrier density.

Disclosure of Invention

The invention aims to provide a PANI/Co-Fe LDHs/NF composite electrode material and a preparation method thereof, which are prepared by adopting an electropolymerization reaction, and Co-Fe LDHs nanosheets are uniformly distributed on a PANI framework growing on foamed nickel by taking PANI/NF as a carrier.

The invention also aims to provide the application of the PANI/Co-Fe LDHs/NF composite electrode material as an electrocatalytic material, which has more excellent electrocatalytic performance.

The specific technical scheme of the invention is as follows:

a preparation method of PANI/Co-Fe LDHs/NF composite electrode material comprises the following steps:

1) in an acid mixed solution of an aniline monomer, respectively taking a nickel foam, a saturated calomel electrode and a platinum wire as a working electrode, a reference electrode and a counter electrode, and carrying out electropolymerization reaction to obtain a PANI/NF composite electrode material;

2) and (2) performing electrochemical electrodeposition in a mixed solution of a cobalt source and an iron source by taking the PANI/NF composite electrode material prepared in the step 1) as a working electrode, a saturated calomel electrode as a reference electrode and a platinum wire as a counter electrode to obtain the PANI/Co-Fe LDHs/NF composite electrode material.

In the step 1), the voltage of the electropolymerization reaction is 1.0-1.2V, and the time is 2-6 min; the reaction conditions were room temperature.

In the step 1), the acidic mixed solution of aniline monomer is a mixed solution of aniline and an acidic solution, the acidic solution is a sulfuric acid solution, and the concentration of sulfuric acid in the mixed solution is 0.5-2.0 mol.L^-1The concentration of aniline monomer is 0.1-0.2 mol.L^-1(ii) a More preferably, the concentration of sulfuric acid is 1 mol. L^-1The concentration of aniline monomer is 0.1 mol.L^-1Under the condition, aniline monomer forms nano particles on the surface of the foam nickel. An aligned network of nanowires is then formed as the deposition process proceeds. Finally, with further increase of time, the length of the PANI nanowire is further prolonged, and an inter-crosslinked structure is formed.

In the PANI/NF composite electrode material, the size of the PANI nanowire is uniform, and the diameter of the PANI nanowire is 80-100nm, so that Co-Fe LDHs can be uniformly loaded on the surface of the PANI nanowire.

After the polymerization reaction in the step 1) is finished, washing and drying are carried out.

The washing is carried out by sequentially adopting distilled water and ethanol.

The drying is carried out by adopting an oven, the drying temperature is 60-80 ℃, and the drying time is 4-24 h.

The cobalt source in the step 2) is cobalt chloride, cobalt sulfate, cobalt acetate or cobalt nitrate; the iron source is ferrous sulfate or ferrous chloride;

the voltage of the electrodeposition in the step 2) is (-0.5) - (-0.7) V, the time is 400-600s, and the reaction condition is room temperature.

The cobalt source in the step 2) is cobalt chloride, cobalt sulfate, cobalt acetate or cobalt nitrate, and the concentration of the mixed solution is 0.06-0.10 mol.L^-1(ii) a The iron source is ferrous sulfate or ferrous chloride, and the concentration of the iron source in the mixed solution is 0.015-0.025 mol.L^-1(ii) a Preferably, the concentration of the cobalt source in the mixed solution is 0.08mol · L^-1The concentration of the iron source in the mixed solution is 0.020 mol.L^-1(ii) a Thereby ensuring sufficient Co²⁺And Fe²⁺Adsorbing on the PANI surface and forming Co-Fe LDHs nano-sheets.

After electrochemical electrodeposition in the step 2), filtering, washing and drying a product;

the washing is carried out by sequentially adopting distilled water and ethanol; the drying is carried out by adopting an oven, the drying temperature is 60-80 ℃, and the drying time is 4-24 h.

The PANI/Co-Fe LDHs/NF composite electrode material prepared in the step 2), the diameter of the Co-Fe LDHs nanosheet is 50-80nm, the thickness of the Co-Fe LDHs nanosheet is 5-8nm, and the Co-Fe LDHs nanosheet is uniformly distributed on a PANI framework growing on the foamed nickel.

According to the preparation method of the PANI/Co-Fe LDHs/NF composite electrode material, provided by the invention, the Co-Fe LDHs nanosheets can be uniformly distributed on the PANI framework growing on the foamed nickel by adopting the method. The Co-Fe LDHs nanosheets have the diameters of 50-80nm and the thicknesses of 5-8nm, and are uniformly distributed on PANI frameworks growing on the foamed nickel.

The PANI/Co-Fe LDHs/NF composite electrode material provided by the invention is applied as an OER electrocatalytic material, and has excellent performance.

According to the invention, Co-Fe LDHs is loaded on polyaniline to serve as a conductive polymer, and PANI has good conductivity. In addition, PANI also has good hydrophilicity and electrochemical stability due to its unique pi-conjugated structure. At the same time, PANI can also modulate the electronic structure of the catalyst through interaction with other electrocatalysts. And with the addition of PANI, the dispersibility of the electrocatalyst is improved, so that the active sites of the reaction are increased, the electron/proton transmission in the electrochemical reaction process is promoted, and the service life of the material is prolonged. Nickel foam is an electrode substrate material that has good electrical conductivity, which is beneficial for accelerating electron transport. In addition, due to the unique structure and the large specific surface area, the dispersion of the catalyst is facilitated. Therefore, the electrode material directly grown on the foamed nickel can not only avoid the influence of the binder on the electrode material, but also has more excellent electrocatalytic activity and stability than the powdery electrocatalytic material.

Compared with the prior art, the invention has the beneficial effects that:

1) the electrochemical method has simple and rapid preparation and easy repetition.

2) The preparation method can obtain PANI/Co-Fe LDHs/NF, which is mainly characterized in that Co-Fe LDHs nanosheets are uniformly distributed on the PANI framework.

3) Compared with PANI/Co-Fe LDHs powder, the PANI/Co-Fe LDHs grown on the foamed nickel has more excellent electrocatalytic performance. At current densityIs 10 mA.cm^-2When the voltage is over-potential is 240mV, Tafel slope is 94.9mV dc^-1. The sample also had excellent stability. After 12h of continuous operation, the potential of the PANI/Co-Fe LDHs electrocatalyst is increased by only 0.010V.

4) The PANI/Co-Fe LDHs/NF composite electrode material has great application potential in the field of electrocatalysis.

Drawings

FIG. 1 is an SEM image of a product of the invention; wherein a is the SEM image of PANI/NF in example 1; b is the SEM image of the PANI/Co-Fe LDHs/NF composite electrode material in the example 1;

FIG. 2 is the XRD pattern of the PANI/NF and PANI/Co-Fe LDHs/NF composite electrode material of example 1;

FIG. 3 is an energy spectrum of the PANI/Co-Fe LDHs/NF composite electrode material in example 1;

FIG. 4 is an infrared image of the PANI/NF and PANI/Co-Fe LDHs/NF composite electrode materials of example 1;

FIG. 5 is the XPS photoelectron survey spectrum of the PANI/Co-Fe LDHs/NF composite electrode material of example 1;

FIG. 6 is a high resolution N1s, Co 2p, Fe 2p and Ni2p XPS photoelectron spectra of PANI/Co-Fe LDHs/NF composite electrode material of example 1;

FIG. 7 is an SEM image; wherein a is the SEM image of PANI/NF in example 2; b is the SEM image of the PANI/Co-Fe LDHs/NF composite electrode material in the example 2;

FIG. 8 is an SEM image; wherein a is the SEM image of PANI/NF in example 3; b is the SEM image of the PANI/Co-Fe LDHs/NF composite electrode material in the example 3;

FIG. 9 is a graph comparing the linear voltammetry performance of PANI/Co-Fe LDHs and PANI/Co-Fe LDHs/NF;

FIG. 10 is a Tafel slope plot, a peak current difference plot, and a Nyquist plot for PANI/Co-Fe LDHs and PANI/Co-Fe LDHs/NF;

FIG. 11 is a graph of chronopotentiometry curves for PANI/Co-Fe LDHs and PANI/Co-Fe LDHs/NF.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.

The invention provides a preparation method of PANI/Co-Fe LDHs/NF composite electrode material, which comprises the following steps:

1) in a mixed solution of sulfuric acid and aniline monomers, respectively taking foamed nickel, a saturated calomel electrode and a platinum wire as a working electrode, a reference electrode and a counter electrode, and sequentially carrying out electropolymerization reaction, washing and drying to obtain a PANI/NF composite electrode material; the voltage of the electropolymerization reaction is 1.0-1.2V, the time is 2-6min, and the electropolymerization reaction is carried out at room temperature. The sulfuric acid concentration in the mixed solution is 0.5-2.0 mol.L^-1The concentration of aniline monomer is 0.1-0.2 mol.L^-1(ii) a Washing the product with distilled water and ethanol; drying the washed product by using an oven at the temperature of 60-80 ℃ for 4-24 h; the PANI prepared by the method has uniform linear morphology, and the diameter of the PANI is 80-100 nm.

2) Performing electrochemical electrodeposition in a mixed solution of a cobalt source and an iron source by taking the PANI/NF prepared in the step 1) as a working electrode, a saturated calomel electrode as a reference electrode and a platinum wire as a counter electrode, and then filtering, washing and drying a product to obtain a PANI/Co-Fe LDHs/NF composite electrode material; the voltage of electrodeposition is (-0.5) - (-0.7) V, and the time is 400-; the concentration of cobalt source in the mixed solution is 0.06-0.10 mol.L^-1The concentration of the iron source is 0.015-0.025mol per liter^-1(ii) a The product was washed with distilled water and ethanol. Drying the washed product in an oven at 60-80 deg.CThe time is 4-24 h. The shape of the PANI/Co-Fe LDHs/NF composite electrode material prepared by the method is mainly represented by that Co-Fe LDHs nanosheets are uniformly distributed on a PANI framework growing on foamed nickel.

The following is a detailed description by way of example:

example 1

A preparation method of PANI/Co-Fe LDHs/NF composite electrode material comprises the following steps:

1) preparing the PANI/NF composite electrode:

1-1) 0.005mol of aniline monomer was added to 50mL of 1 mol. L^-1Uniformly stirring in the sulfuric acid solution;

1-2) respectively taking a foamed nickel electrode, a saturated calomel electrode and a platinum wire electrode as a working electrode, a reference electrode and a counter electrode, and electropolymerizing for 5min at room temperature under the condition that the voltage is 1.2V;

1-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/NF composite electrode.

2) Preparing the PANI/Co-Fe LDHs/NF composite electrode material:

2-1) dissolving 0.004mol of cobalt chloride and 0.001mol of ferrous sulfate in 50mL of deionized water, and uniformly stirring;

2-2) respectively taking the PANI/NF composite electrode, the saturated calomel electrode and the platinum wire electrode prepared in the step 1) as a working electrode, a reference electrode and a counter electrode, and performing electrodeposition for 500s at room temperature under the condition of-0.7V voltage;

2-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/Co-Fe LDHs/NF composite electrode.

PANI/NF and PANI/Co-Fe LDHs/NF were analyzed using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), X-ray energy spectroscopy (EDS), X-ray photoelectron diffraction (XPS), and infrared spectroscopy (FT-IR).

As shown in FIG. 1, a in FIG. 1 is an SEM image of PANI/NF of example 1, where it can be seen that PANI has a uniform linear morphology with a diameter of about 90 nm. B in FIG. 1 is SEM image of PANI/Co-Fe LDHs/NF in example 1, and it can be seen that the Co-Fe LDHs nanosheets after the electrodeposition process have a diameter of about 70nm and a thickness of about 6nm, and are uniformly distributed on PANI nanowires.

FIG. 2 shows XRD patterns of PANI/NF and PANI/Co-Fe LDHs/NF. The strong diffraction peaks at 44.6 °, 52.0 ° and 76.4 ° correspond to the characteristic peaks of the nickel foam (marked with black squares). The weaker broad diffraction peak at 21.1 ° corresponds to the (020) crystal plane of PANI (marked with a plum blossom). After the Co-Fe LDHs nanosheets are loaded, no obvious characteristic peak of the Co-Fe LDHs appears, which is probably caused by the fact that the characteristic peak of the Co-Fe LDHs is low in strength and is covered by the characteristic peak of the strong foam nickel. In addition, to further prove the successful synthesis of PANI/Co-Fe LDHs/NF, we performed the following tests.

The X-ray energy spectrum (EDS) of PANI/Co-Fe LDHs/NF is shown in FIG. 3, which shows that the PANI/Co-Fe LDHs/NF electro-catalytic material mainly contains C, N, O, Co, Fe, Ni and Cl elements. Wherein C and N are derived from PANI, and Co, Fe and O are derived from Co-Fe LDHs. The signal of Ni element is mainly due to the reaction on the foam nickel. At the same time, since CoCl is used₂As a cobalt source, a stronger signal of Cl element appears, due to Cl^-Caused by intercalation effect on Co-Fe LDHs.

As shown in a in FIG. 4, the prepared PANI/NF was 1571cm^-1、1489cm^-1、1315cm^-1、1238cm^-1、1102cm^-1And 809cm^-1A distinct absorption peak appears. 1571cm^-1And 1489cm^-1The absorption peak at (A) belongs to the absorption peak of C ═ C tensile vibration of quinone and benzene ring, 1315cm^-1And 1238cm^-1The peak at (A) is a tensile vibration absorption peak of C ═ N and C-N, respectively, at 1102cm^-1And 809cm^-1The peak at (b) is a tensile vibration absorption peak of N ═ Q ═ N and a bending vibration absorption peak of C — H, respectively. After loading with Co-Fe LDHs, there was no change in the characteristic peak position of PANI but a significant decrease in intensity, and some new peaks appeared (b in fig. 4). At 682cm^-1And 587cm^-1The peaks at (A) are tensile vibration absorption peaks of Co-O and Fe-O, respectively.

As shown in FIG. 5, the XPS survey of PANI/Co-Fe LDHs/NF showed that it contained primarily C, N, O, Co, Fe and Ni elements. As shown in a in fig. 6, the peak of N1s may be divided into three peaks at 398.4, 399.3, and 400.0eV, which correspond to quinoid imines (═ N-), benzenoid amines (-NH-), and positively charged nitrogen (-NH-)⁺-) which demonstrates the presence of PANI. In the Co 2p photoelectron spectrum of b in FIG. 6, two peaks were observed at 781.4eV and 796.9eV, which correspond to Co 2p_3/2And Co 2p_1/2In addition, two satellite peaks were observed at 787.2eV and 801.0eV, which indicate that the valence state of Co in the compound is divalent. This is consistent with previous reports. In FIG. 6 c shows two characteristic peaks for Fe 2p at 711.9eV and 725.0eV and two satellite peaks at 715.8eV and 732.4 eV. This demonstrates that the iron element is present in trivalent form. In XPS spectra of Ni2p (d in FIG. 6), two peaks at 852.5eV and 869.8eV belong to Ni⁰Ni2p_3/2And Ni2p_1/2The characteristic peaks at 855.9eV and 873.6eV and the satellite peaks at 861.3eV and 879.6eV correspond to Ni²⁺Ni2p of_3/2And Ni2p_1/2. This is also due to the reaction occurring on the nickel foam.

Example 2

A preparation method of PANI/Co-Fe LDHs/NF composite electrode material comprises the following steps:

1) preparing the PANI/NF composite electrode:

1-1) 0.005mol of aniline monomer was added to 50mL of 1 mol. L^-1Uniformly stirring in the sulfuric acid solution;

1-2) carrying out electropolymerization for 4min under the condition of voltage of 1.2V by using a foamed nickel electrode, a saturated calomel electrode and a platinum wire electrode as a working electrode, a reference electrode and a counter electrode;

1-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/NF composite electrode.

2) Preparing the PANI/Co-Fe LDHs/NF composite electrode material:

2-1) dissolving 0.005mol of cobalt chloride and 0.00125mol of ferrous sulfate in 50mL of deionized water, and uniformly stirring;

2-2) carrying out electrodeposition for 500s under the condition that the voltage is-0.6V by taking the PANI/NF composite electrode, the saturated calomel electrode and the platinum wire electrode prepared in the step 1) as a working electrode, a reference electrode and a counter electrode;

2-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/Co-Fe LDHs/NF composite electrode.

PANI/NF and PANI/Co-Fe LDHs/NF were analyzed by Scanning Electron Microscopy (SEM).

As shown in FIG. 7, a in FIG. 7 is the SEM image of PANI/NF in example 2, where it can be seen that PANI has uniform linear morphology with a diameter of about 95 nm. B in FIG. 7 is SEM image of PANI/Co-Fe LDHs/NF in example 1, and it can be seen that the Co-Fe LDHs nanosheets after electrodeposition process had a diameter of about 66nm and a thickness of about 5nm, and were uniformly distributed on PANI nanowires.

Example 3

A preparation method of PANI/Co-Fe LDHs/NF composite electrode material comprises the following steps:

1) preparation of PANI/NF composite electrode

1-1) 0.005mol of aniline monomer was added to 50mL of 1.5 mol. L^-1Uniformly stirring in the sulfuric acid solution;

1-2) electropolymerization is carried out for 5min under the condition that the voltage is 1.2V by taking a foamed nickel electrode, a saturated calomel electrode and a platinum wire electrode as a working electrode, a reference electrode and a counter electrode respectively;

1-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/NF composite electrode.

2) Preparation of PANI/Co-Fe LDHs/NF composite electrode material

2-1) dissolving 0.004mol of cobalt chloride and 0.001mol of ferrous sulfate in 50mL of deionized water, and uniformly stirring;

2-2) carrying out electrodeposition for 400s under the condition that the voltage is-0.6V by using the prepared PANI/NF composite electrode, saturated calomel electrode and platinum wire electrode as a working electrode, a reference electrode and a counter electrode;

2-3) washing the foam nickel loaded with the sample by using distilled water and ethanol in sequence, and then drying for 4h at the temperature of 60 ℃ to obtain the PANI/Co-Fe LDHs/NF composite electrode.

PANI/NF and PANI/Co-Fe LDHs/NF were analyzed by Scanning Electron Microscopy (SEM).

As shown in FIG. 8, a in FIG. 8 is the SEM image of PANI/NF in example 3, where it can be seen that PANI has uniform linear morphology with a diameter of about 100 nm. B in FIG. 8 is SEM image of PANI/Co-Fe LDHs/NF in example 1, and it can be seen that the Co-Fe LDHs nanosheets after the electrodeposition process had a diameter of about 50nm and a thickness of about 8nm, and were uniformly distributed on the PANI nanowires.

Example 4

The three-electrode electrocatalytic performance of the PANI/Co-Fe LDHs/NF composite electrode material prepared in the example 1 is tested. The method specifically comprises the following steps: the area loaded with the sample is 1cm²The nickel foam, the saturated Ag/AgCl electrode and the graphite rod of (a) were used as working, reference and counter electrodes, respectively, and their electrochemical performance was analyzed on a CHI660E electrochemical workstation. Further, the concentration is 1 mol. L^-1The KOH solution of (3) as an electrolyte. At a scan rate of 5mV · s^-1The polarization curve of the sample was measured. The current density range is 1-10 mA-cm^-2The tafel slope of the sample was calculated. In the voltage range of 0-0.55V, different scanning rates (20 mV. s) are obtained^-1、40mV·s^-1、60mV·s^-1、80mV·s^-1、100mV·s^-1、120mV·s^-1) Cyclic voltammogram of the sample below. At a current density of 10mA cm^-2Under the conditions (1), a chronopotentiometry curve of the sample was obtained. Electrochemical Impedance Spectroscopy (EIS) data were obtained for samples over a frequency range of 0.1-1000kHz and at a bias potential of 1.5V. The test result shows that: the PANI/Co-Fe LDHs/NF composite electrode material has higher electrocatalytic activity.

As shown in the polarization curve of FIG. 9, the PANI/Co-Fe LDHs/NF composite material has the most excellent electrocatalytic activity. The initial potential is about 1.251V, which is obviously less than 1.410V of PANI/Co-Fe LDHs.

The preparation method of the PANI/Co-Fe LDHs comprises the following steps: first 0.15g of methyl orange was dissolved in 100mL of water. To this solution was then added 1mL of aniline monomer (AN) slowly and stirred for 30 minutes. Then, 20mL of 0.5 mol. L was slowly added^-1Ammonium Persulfate Solution (APS) cold treated while ice-cooling for 24 hours. Finally, the product was filtered, washed and dried. 0.1g of PANI was then dispersed in 20mL of water. Then 0.582g of Co (NO) was added to this solution₃)₂And 0.099g FeCl₂. Then, 0.5mL of aqueous ammonia was added slowly. Followed by reaction at 120 ℃ for 6 h. After the temperature had dropped to room temperature, the product was filtered, washed and dried.

When the current density is 10mA cm^-2The potential of PANI/Co-Fe LDHs/NF is 1.470V, and the formula eta is E_RHE1.23 calculation shows that at this current density, the overpotential for PANI/Co-Fe LDHs/NF is 240mV, which is significantly lower than 261mV for PANI/Co-Fe LDHs. Due to the unique structure and high conductivity of the foamed nickel and the synergistic effect between PANI and Co-Fe LDHs, the electrocatalytic activity of the material is improved.

The Tafel slope is an important way to explore the electro-catalytic material dynamics, and can be obtained from the Tafel equation. Thus, the Tafel slopes of PANI/Co-Fe LDHs/NF and PANI/Co-Fe LDHs were calculated from the LSV data with the overpotential on the ordinate and log (j) on the abscissa and are shown in FIG. 10 a. As shown in the figure, the Tafel slope of PANI/Co-Fe LDHs/NF is 94.9mV dec^-167.9mV dec of PANI/Co-Fe LDHs^-1. This is probably due to the smaller reaction rate and the larger mass transfer rate of PANI/Co-Fe LDHs grown on nickel foam during the reaction.

The electrochemical active areas of PANI/Co-Fe LDHs/NF and PANI/Co-Fe LDHs are explored through an electrochemical double-layer capacitor by adopting a simple cyclic voltammetry method. FIG. 10 b is a graph of the peak current difference between PANI/Co-Fe LDHs/NF and PANI/Co-Fe LDHs, and the electric double layer capacitance (C) of the material can be obtained from the slopes of the two curves_dl). After fitting, the C of PANI/Co-Fe LDHs/NF_dlThe value was 194.1 mF. cm^-2Is far greater than67mF cm of PANI/Co-Fe LDHs^-2. The result shows that PANI/Co-Fe LDHs/NF has more reaction active sites and larger reaction active area. This is probably due to the synergistic effect between PANI and Co-Fe LDHs and the porous structure and higher conductivity of the nickel foam, which improves the dispersibility and conductivity of the material.

The OER kinetics and electrical properties of PANI/Co-Fe LDHs/NF were further analyzed by Electrochemical Impedance Spectroscopy (EIS). As shown in FIG. 10 c, compared to PANI/Co-Fe LDHs, the semi-circular diameter of the PANI/Co-Fe LDHs/NF material is the smallest and the intersection with the solid axis is much smaller than the PANI/Co-Fe LDHs. This indicates that the electrocatalyst improves its OER performance in two ways. On the one hand by increasing its charge transfer efficiency and on the other hand by decreasing its ohmic resistance. This result is consistent with inferences drawn from the electrochemically active area.

At a current density of 10mA cm^-2The stability of the different materials was determined by chronopotentiometry under the conditions of (1). As shown in FIG. 11, after a continuous test of 12h, the voltage of the PANI/Co-Fe LDHs/NF composite material increased by only 0.010V, while the voltage of the PANI/Co-Fe LDHs increased by 0.019V after a continuous test of 11 h. The result shows that PANI/Co-Fe LDHs/NF has more excellent stability. This is probably because the PANI/Co-Fe LDHs on the nickel foam have higher dispersibility than PANI/Co-Fe LDHs powder, and excessive reaction of a certain active site is avoided, thereby improving the stability thereof.

The invention is described above with reference to the accompanying drawings. It is to be understood that the specific implementations of the invention are not limited in this respect. Various insubstantial improvements are made by adopting the method conception and the technical scheme of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.