Iron-nickel bimetal organic gel material and preparation method thereof

Abstract

The invention provides an iron-nickel bimetal organic gel material and a preparation method thereof, and belongs to the technical field of water electrolysis oxygen evolution application. A simple one-step water phase synthesis method is adopted, a Fe < 3 + > solution, a Ni < 2 + > solution and an organic ligand solution are mixed and stood, and freeze drying is performed to obtain the target gel material. The gel material prepared by the method has an open pore structure, good conductivity and iron-nickel bimetal active sites, and has high activity and stability on catalytic electrolysis water oxygen evolution reaction under an alkaline condition. And moreover, the catalytic active site is non-noble metal, so that the production cost is saved.

Description

Technical Field

[0001] The invention relates to the cross-technical fields of material chemistry, electrochemistry, catalytic chemistry and the like, and in particular to a bimetallic organic gel electrocatalytic material and a preparation method thereof. Background Art

[0002] As a new type of renewable energy system, hydrogen energy has the advantages of high energy density and pollution-free combustion, and is expected to replace traditional fossil fuels. Moreover, hydrogen can not only be used as a fuel, but also in industrial production, chemical raw materials, biomedicine and other fields, with high economic value. Using renewable energy, such as solar energy and wind energy, to convert into electricity and electrolyze water to produce hydrogen is a green and clean way to produce hydrogen. Traditional water electrolysis methods are inefficient and require a lot of electricity. Improving the efficiency of water electrolysis and reducing costs are the key to promoting the commercialization of hydrogen energy. The development of new catalytic materials can improve the efficiency of water electrolysis, reduce energy consumption, and help reduce the cost of water electrolysis, making it possible to expand its application. In the process of water electrolysis to produce hydrogen, the hydrogen evolution reaction (HER) occurring on the cathode and the oxygen evolution reaction (OER) occurring on the anode occur simultaneously. Among them, the slow four-electron transfer OER process at the anode reduces the efficiency of the overall water splitting. The use of highly active and stable electrocatalysts can improve the catalytic performance and energy utilization. At present, precious metal Ru-based catalysts usually have excellent OER catalytic performance, among which RuO2 is often used as a benchmark catalyst for OER. However, due to the scarcity, low durability and high cost of Ru-based catalysts, there is still an urgent need to develop low-cost, highly active and stable new catalytic materials for large-scale commercial applications. In recent years, non-precious metal electrocatalytic materials with abundant reserves and low prices on the earth have also shown excellent performance in the overall water electrolysis catalytic process. In particular, Co-based, Fe-based and Ni-based materials have been continuously developed and are expected to become low-cost industrial electrocatalysts. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the anode OER half-reaction in the existing water electrolysis reaction mostly uses Ru-based catalysts, which are high in cost and limited in scope of application, and to provide an iron-nickel bimetallic organic gel electrocatalytic material (FeNi-MOG) and a preparation method thereof. The metal organic gel has an adjustable porous structure, multifunctional ligands and a defined metal active center. The optimized metal organic gel has good electrical conductivity, a simple synthesis method, and is easy to apply on a large scale. The FeNi-MOG electrocatalyst exhibits excellent catalytic activity in alkaline electrolytes.

[0004] The technical solution adopted by the present invention is to provide an iron-nickel bimetallic organic gel electrocatalytic material, characterized in that Fe 3+ and Ni 2+After coordination reaction with organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid in water phase, the target product FeNi-MOG is obtained by freeze drying.

[0005] The preparation method of the iron-nickel bimetallic organic gel electrocatalytic material is as follows:

[0006] Step 1: Dissolve the metallic iron salt and nickel salt in deionized water to prepare Fe 3+ Solution and Ni 2+ Solution; the molar ratio of metal iron salt, metal nickel salt and deionized water is 1:1:2000-3000;

[0007] Step 2: adding an organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and an organic base into deionized water, and preparing a mixed solution after ultrasonic dispersion; the molar ratio of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid, the organic base and the deionized water is 1:0.05-0.1:2000-3000;

[0008] Step 3: Take an equal volume of Fe prepared in step 1 3+ Solution and Ni 2+ The solution is added dropwise to the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and the organic base prepared in step 2, stirred evenly, and allowed to stand at 20-50° C. for 1-5 hours; the obtained gel product is freeze-dried for 12-24 hours, the solid product is washed with deionized water for 3-5 times, and dried at 50-100° C. for 10-12 hours under a vacuum degree of 133 Pa to obtain the target product FeNi-MOG; Fe 3+ Solution, Ni 2+ The volume ratio of the solution to the mixed solution of the organic ligand and the organic base is 1:1:0.8-1.2.

[0009] The metal iron salt and the metal nickel salt are preferably iron chloride and nickel chloride.

[0010] The organic base is preferably ethylenediamine and triethylamine.

[0011] The freeze-drying time is preferably 24 hours.

[0012] Beneficial effects of the present invention:

[0013] The iron-nickel bimetallic organic gel electrocatalytic material prepared by the synthesis method provided by the present invention has the following advantages:

[0014] (1) The iron-nickel metal salt raw materials used are cheap and easy to obtain, the synthesis conditions are mild, the operation is simple, the yield is high, and it is conducive to large-scale production and application;

[0015] (2) During the electrocatalytic process, synergistic coupling occurs between the metal active sites generated by the in situ electrochemical reconstruction of the iron-nickel bimetallic organogel FeNi-MOG, which makes the FeNi-MOG electrocatalyst have better catalytic activity and stability in alkaline electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Transmission electron microscopy image of FeNi-MOG prepared in Example 1;

[0017] Figure 2 X-ray diffraction pattern of FeNi-MOG prepared in Example 1;

[0018] Figure 3 Thermogravimetric analysis of FeNi-MOG prepared in Example 1;

[0019] Figure 4 X-ray photoelectron spectrum of FeNi-MOG prepared in Example 1;

[0020] Figure 5 The oxidation polarization curve of FeNi-MOG prepared in Example 1 in the electrolysis of water in 1.0 mol / L KOH solution;

[0021] Figure 6 Chronoamperometric test diagram of FeNi-MOG prepared in Example 1 in 1.0 mol / L KOH solution. DETAILED DESCRIPTION

[0022] The present invention is further described in detail with reference to the accompanying drawings and embodiments. It should be pointed out that the purpose is only to better understand the content of the present invention rather than to limit the protection scope of the present invention.

[0023] Example 1

[0024] Step 1: Dissolve 0.01 mol ferric chloride and 0.01 mol nickel chloride in 500 mL deionized water to prepare Fe 3+ Solution and Ni 2+ Solution;

[0025] Step 2: 0.01 mol of an organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and 0.0005 mol of triethylamine were added to 500 mL of deionized water, and ultrasonically dispersed to prepare a mixed solution;

[0026] Step 3: Take the Fe prepared in step 1 3+1mL of solution and Ni 2+ 1 mL of the solution was added dropwise into 2 mL of the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and triethylamine prepared in step 2, stirred evenly, and allowed to stand at 20 ° C for 2 hours; the gel product was freeze-dried for 24 hours, and the solid product was washed 3 times with deionized water. After drying at 50 ° C for 12 hours under a vacuum degree of 133 Pa, the target product FeNi-MOG was obtained.

[0027] The structure, composition and electrolytic water oxidation performance of the FeNi-MOG synthesized in Example 1 were characterized.

[0028] Figure 1 This is a transmission electron micrograph of the FeNi-MOG prepared in Example 1; as can be seen from the figure, the gel presents a nanofiber structure, and this unique structure not only enhances the electrical conductivity, but also promotes mass transfer between the reactants and the active sites of the catalyst.

[0029] Figure 2 This is the X-ray diffraction pattern of FeNi-MOG prepared in Example 1; a broad peak appears at about 26.7°, and there are no other obvious high-intensity diffraction peaks, indicating that the synthesized gel material has a low degree of crystallinity and is an amorphous phase material.

[0030] Figure 3 This is the thermogravimetric analysis diagram of FeNi-MOG prepared in Example 1; it can be seen from the figure that there are two sections of obvious weight loss. It is speculated that the first section of the decline is due to the evaporation of a small amount of residual solvent in the sample; the second section is caused by the decomposition of the sample under high temperature conditions.

[0031] Figure 4 This is the X-ray photoelectron spectrum of FeNi-MOG prepared in Example 1; the presence of C, N, O, Fe and Ni elements can be seen from the figure.

[0032] Figure 5 This is the polarization curve of the FeNi-MOG catalyst prepared in Example 1 for electrocatalytic oxygen evolution in 1.0 mol / L KOH solution; it can be seen from the figure that at 10 mA / cm 2 At a current density of , FeNi-MOG requires a small overpotential of 320 mV, proving that FeNi-MOG has excellent electrocatalytic oxygen evolution performance.

[0033] Figure 6 The FeNi-MOG catalyst prepared in Example 1 was subjected to a chronoamperometric test in a 1.0 mol / L KOH solution. As can be seen from the figure, FeNi-MOG has good stability. At an overpotential of 320 mV, the current density only decreased by 7.8% after 240,000 seconds.

[0034] Example 2

[0035] Step 1: Dissolve 0.01 mol ferric chloride and 0.01 mol nickel chloride in 550 mL deionized water to prepare Fe 3+ Solution and Ni 2+ Solution;

[0036] Step 2: 0.01 mol of an organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and 0.0006 mol of triethylamine were added to 500 mL of deionized water, and ultrasonically dispersed to prepare a mixed solution;

[0037] Step 3: Take the Fe prepared in step 1 3+ 1mL of solution and Ni 2+ 1 mL of the solution was added dropwise into 2 mL of the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and triethylamine prepared in step 2, stirred evenly, and allowed to stand at 30 ° C for 5 hours; the gel product was freeze-dried for 12 hours, and the solid product was washed 3 times with deionized water. After drying at 50 ° C for 12 hours under a vacuum degree of 133 Pa, the target product FeNi-MOG was obtained.

[0038] The FeNi-MOG catalyst was tested for electrocatalytic oxygen evolution in a 1.0 mol / L KOH solution, and a current density of 10 mA / cm was achieved at 344 mV. 2 .

[0039] Example 3

[0040] Step 1: Dissolve 0.01 mol ferric chloride and 0.01 mol nickel chloride in 600 mL deionized water to prepare Fe 3+ Solution and Ni 2+ Solution;

[0041] Step 2: 0.01 mol of an organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and 0.0005 mol of ethylenediamine were added to 500 mL of deionized water, and a mixed solution was prepared after ultrasonic dispersion.

[0042] Step 3: Take the Fe prepared in step 1 3+ 1mL of solution and Ni 2+1 mL of the solution was added dropwise into 2 mL of the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and triethylamine prepared in step 2, stirred evenly, and allowed to stand at 50 ° C for 2 hours; the gel product was freeze-dried for 12 hours, and the solid product was washed 3 times with deionized water. After drying at 50 ° C for 12 hours under a vacuum degree of 133 Pa, the target product FeNi-MOG was obtained.

[0043] The FeNi-MOG catalyst was tested for electrocatalytic oxygen evolution in a 1.0 mol / L KOH solution, and a current density of 10 mA / cm was achieved at 352 mV. 2 .

[0044] Example 4

[0045] Step 1: Dissolve 0.01 mol ferric chloride and 0.01 mol nickel chloride in 500 mL deionized water to prepare Fe 3+ Solution and Ni 2+ Solution;

[0046] Step 2: Add 0.01 mol of organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and 0.001 mol of ethylenediamine into 500 mL of deionized water, and prepare a mixed solution after ultrasonic dispersion.

[0047] Step 3: Take the Fe prepared in step 1 3+ 1mL of solution and Ni 2+ 1 mL of the solution was added dropwise into 2 mL of the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and triethylamine prepared in step 2, stirred evenly, and allowed to stand at 20 ° C for 5 hours; the gel product was freeze-dried for 20 hours, and the solid product was washed 3 times with deionized water and dried at 50 ° C for 12 hours under a vacuum degree of 133 Pa to obtain the target product FeNi-MOG.

[0048] The FeNi-MOG catalyst was tested for electrocatalytic oxygen evolution in a 1.0 mol / L KOH solution, and a current density of 10 mA / cm was achieved at 338 mV. 2 .

[0049] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the field, corresponding changes and substitutions can be made according to the technical solutions and inventive concepts of the present invention, and the same performance or use should be regarded as the protection scope of the present invention.

Claims

1. An iron-nickel bimetallic organic gel electrocatalytic material and a preparation method thereof, characterized in that The steps include: Step 1: Dissolve the metallic iron salt and nickel salt in deionized water to prepare Fe 3+ Solution and Ni 2+ Solution; the molar ratio of metal iron salt, metal nickel salt and deionized water is 1:1:2000-3000; Step 2: adding an organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and an organic base into deionized water, and preparing a mixed solution after ultrasonic dispersion; the molar ratio of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid, the organic base and the deionized water is 1:0.05-0.1:2000-3000; Step 3: Take an equal volume of Fe prepared in step 1 3+ Solution and Ni 2+ The solution is added dropwise to the mixed solution of the organic ligand 5,5'-(6-(4-carboxyphenylamino)-1,3,5-triazine-2,4-diimino)diisophthalic acid and the organic base prepared in step 2, stirred evenly, and allowed to stand at 20-50° C. for 1-5 hours; the obtained gel product is freeze-dried for 12-24 hours, the solid product is washed with deionized water for 3-5 times, and dried at 50-100° C. for 10-12 hours under a vacuum degree of 133 Pa to obtain the target product FeNi-MOG; Fe 3+ Solution, Ni 2+ The volume ratio of the solution to the mixed solution of the organic ligand and the organic base is 1:1:0.8-1.

2.

2. The method for preparing the iron-nickel bimetallic organic gel material according to claim 1, characterized in that The metal iron salt and metal nickel salt used in step 1 are preferably ferric chloride and nickel chloride.

3. The method for preparing the iron-nickel bimetallic organic gel material according to claim 1, characterized in that Step 1: preparing Fe 3+ Solution and Ni 2+ The solutions have the same concentration.

4. The method for preparing the iron-nickel bimetallic organic gel material according to claim 1, characterized in that The organic base used in step 2 is preferably ethylenediamine and triethylamine.

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