Iron phthalocyanine nanotube material, and preparation method and application thereof

Abstract

The application belongs to the field of composite materials, and particularly relates to an iron phthalocyanine nanotube material and a preparation method and application thereof. The preparation method of the material is as follows: terephthalonitrile, iron acetate tetrahydrate and molybdate tetrahydrate are put into an ethylene glycol solution and stirred, then the solution is poured into a hydrothermal reaction kettle for reaction. After natural cooling to ambient temperature, the solution is washed with dilute HCl, hot water and ethanol for multiple times to remove residual reagents. The obtained nanocrystals are dried in a vacuum oven to obtain the iron phthalocyanine nanotube material. The average length and diameter of the iron phthalocyanine nanotube are in the ranges of 2-6 microns and 100-400 nanometers, respectively. The method has the characteristics of low preparation cost, simple operation, low equipment requirement and recyclability. The iron phthalocyanine nanotube prepared by the method can be used as a new type of electrocatalyst for proton exchange membrane fuel cells, methanol fuel cells and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite materials, and particularly relates to an iron phthalocyanine nanotube material and a preparation method and application thereof. BACKGROUND

[0002] Fuel cell is a new energy conversion device, and its anode reaction can convert chemical energy of specific fuel into electric energy through electrochemical catalysis process, so as to realize energy conversion. Fuel cell is an energy conversion device, which is an isothermal device for directly converting chemical energy stored in fuel and oxidant into electric energy according to electrochemical principle, i.e. principle of primary cell, so that the actual process is a redox reaction. Fuel cell is mainly composed of four parts, i.e. anode, cathode, electrolyte and external circuit. Fuel gas and oxidizing gas are respectively introduced into the anode and cathode of the fuel cell. The fuel gas releases electrons on the anode, the electrons are conducted to the cathode through the external circuit and combined with the oxidizing gas to generate ions. The ions migrate to the anode through the electrolyte under the action of the electric field and react with the fuel gas to form a loop to generate electric current. At the same time, due to the electrochemical reaction itself and the internal resistance of the cell, the fuel cell will also generate a certain amount of heat. The cathode and anode of the cell not only conduct electrons, but also act as catalysts for the redox reaction. When the fuel is a hydrocarbon, the anode requires higher catalytic activity. The cathode and anode are usually porous structures to facilitate the entry of reaction gas and the discharge of product. The electrolyte plays a role in transferring ions and separating fuel gas and oxidizing gas. In order to prevent the mixture of the two gases from causing short circuit in the cell, the electrolyte is usually dense. Fuel cell is a power generation device for directly converting chemical energy of fuel and oxidant into electric energy through electrochemical reaction. Fuel cell can theoretically operate at a heat efficiency close to 100%, and has high economic efficiency. At present, various fuel cells in actual operation are limited by various technical factors, and considering the energy consumption of the entire device system, the total conversion efficiency is mostly in the range of 45%-60%, and can reach more than 80% if the heat utilization is considered. In addition, fuel cell device contains few or no moving parts, is reliable in operation, needs less maintenance, and is quieter than traditional generator set. In addition, the electrochemical reaction is clean and complete, and produces little harmful substances. All these make fuel cell be regarded as a promising energy power device.

[0003] The electrode reaction of a fuel cell is usually an oxygen reduction reaction (ORR). From the perspective of energy utilization efficiency, a 4-electron reaction would be more ideal. Therefore, the exploration of the oxygen reduction reaction and the development of catalysts are very important. Today, the most advanced platinum (Pt) -based catalysts for ORR have the disadvantages of high cost (20% of the cost of a fuel cell), resource scarcity, and poor durability. Therefore, the development of alternatives to Pt catalysts is a key issue facing the large-scale promotion of fuel cells. There are three main directions for the development of new ORR catalysts: 1) low-Pt catalysts: Pt-transition metal alloys or Pt nanostructures; 2) transition metal-based Pt-free catalysts; and 3) non-metallic catalysts. Among them, transition metal-based catalysts are favored due to their low cost, abundant precursor sources, and high catalytic activity. Carbon materials modified by transition metal-based nanomaterials are also one of the research hotspots due to their high catalytic activity and good time stability.

[0004] In recent years, N-doped porous carbon structures modified by transition metal species have been widely studied as efficient ORR electrocatalysts due to their similar activity compared to noble metal-based catalysts, better stability and resistance to methanol and CO, lower price, and more abundant precursor reserves. There have been many reports on ORR active sites and catalytic mechanisms. M / N-C species (M refers to a transition metal element, including Fe, Co, Ni, Cu, Zn, etc.), i.e., a transition metal atom coordinated with surrounding nitrogen and carbon atoms to form a M-Nx-C complex, are considered to be the main active sites of such catalysts, and heteroatom-doped porous carbon has high electrochemical activity. SUMMARY

[0005] It is particularly important to develop non-noble metal catalysts with high activity and stability to fundamentally eliminate the difficulties caused by the high cost of catalysts for the development of fuel cell systems and other battery systems.

[0006] To solve the above-mentioned technical problems, the present application provides a preparation method of an iron phthalocyanine nanotube material, comprising the following steps:

[0007] S11: adding iron salt, ligand and ammonium molybdate into a small molecule alcohol, mixing and then heating to react to obtain a reaction product;

[0008] S12: drying the reaction product after removing impurities to obtain the iron phthalocyanine nanotube material.

[0009] Small nanoblocks are formed by the reaction of terephthalonitrile, iron acetate tetrahydrate and ammonium molybdate tetrahydrate in ethylene glycol solvent. Ethylene glycol forms anion as a nucleophile to attack the cyano group of terephthalonitrile to form a complex intermediate. Then the iron ion is cyclized by four intermediate systems to form a FePc unit, which further generates π-π interaction in a parallel manner to produce iron phthalocyanine nanotube material.

[0010] The iron phthalocyanine nanotube material thus synthesized has a one-dimensional hollow structure, which can act as a mass transfer channel for the reactants, and the high specific surface area of the nanotube structure provides available active sites for adsorption and reduction to promote the electrochemical performance.

[0011] Preferably, the iron salt is iron acetate.

[0012] Preferably, the ligand is terephthalonitrile.

[0013] Preferably, the molar ratio of the ligand to the iron salt is 2-6:1.

[0014] Preferably, the small molecule alcohol is ethanol or ethylene glycol.

[0015] Preferably, in step S11, the mixing time is 10-100 min.

[0016] Preferably, in step S11, the heating reaction temperature is 150-200℃ and the time is 10-15 h.

[0017] Further, in step S12, the method of removing impurities is to separate the mixture B and wash it with HCl, hot water and ethanol.

[0018] Further, in step S12, after removing the residual reagents by impurity removal, the obtained sample is dried in a vacuum oven.

[0019] The present application also provides an iron phthalocyanine nanotube material prepared by the above preparation method.

[0020] Preferably, the length of the iron phthalocyanine nanotube material is 2-6 μm and the diameter is 100-400 nm.

[0021] The present application also provides an electrocatalyst using the above iron phthalocyanine nanotube material.

[0022] The technical solution of the present application has the following advantages compared with the prior art:

[0023] (1) It has excellent electrocatalytic oxygen reduction water production performance in alkaline medium, high water generation selectivity and initial potential.

[0024] (2) The method has the characteristics of low preparation cost, simple operation, low requirement for equipment and recyclability. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM image of the iron phthalocyanine nanotube material in Example 1.

[0026] Figure 2 TEM image of the iron phthalocyanine nanotube material in Example 1.

[0027] Figure 3 SEM image of the iron phthalocyanine nanotube material loaded on graphene.

[0028] Figure 4 XRD image of the iron phthalocyanine nanotube material in Example 1.

[0029] Figure 5 Conductivity test results of graphene, iron phthalocyanine nanotube, graphene and iron phthalocyanine nanotube composite material of Example 1.

[0030] Figure 6 ORR performance test results of graphene, iron phthalocyanine nanotube, graphene and iron phthalocyanine nanotube composite material of Example 1. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with the drawings and specific examples, so that those skilled in the art can better understand the present application and implement it, but the examples are not limiting to the present application.

[0032] Example 1

[0033] First step, 5.76 mmol of p-phenylenedinitrile, 1.44 mmol of iron acetate tetrahydrate and 10 mg of ammonium molybdate tetrahydrate were placed in the inner liner of the reaction kettle.

[0034] Second step, 10 mL of ethylene glycol solvent was added in the inner liner and stirred for 1 h.

[0035] Third step, the hydrothermal reaction kettle was kept at 180℃ for 12 h.

[0036] Fourth step, after natural cooling to ambient temperature, the residual reagents were removed by washing with dilute HCl, hot water and ethanol in sequence. The obtained nanocrystals were dried in a vacuum oven to obtain the iron phthalocyanine nanotube.

[0037] Example 2

[0038] First step, 2.88 mmol of p-phenylenedinitrile, 1.44 mmol of iron acetate tetrahydrate and 10 mg of ammonium molybdate tetrahydrate were placed in the inner liner of the reaction kettle.

[0039] The second step is to add 10 mL of ethylene glycol solvent to the liner and stir for 1 hour.

[0040] The third step is to maintain the temperature of the hydrothermal reactor at 180℃ for 12 hours.

[0041] Fourth, after naturally cooling to ambient temperature, the nanocrystals were washed repeatedly with dilute HCl, hot water, and ethanol to remove residual reagents. The resulting nanocrystals were then dried in a vacuum oven to obtain iron phthalocyanine nanotubes.

[0042] Example 3

[0043] The first step involves placing 8.64 mmol of terephthalonitrile, 1.44 mmol of ferric acetate tetrahydrate, and 10 mg of ammonium molybdate tetrahydrate into the liner of the reactor.

[0044] The second step is to add 10 mL of ethylene glycol solvent to the liner and stir for 1 hour.

[0045] The third step is to maintain the temperature of the hydrothermal reactor at 180℃ for 12 hours.

[0046] Fourth, after naturally cooling to ambient temperature, the nanocrystals were washed repeatedly with dilute HCl, hot water, and ethanol to remove residual reagents. The resulting nanocrystals were then dried in a vacuum oven to obtain iron phthalocyanine nanotubes.

[0047] Example 4

[0048] The first step involves placing 5.76 mmol of terephthalonitrile and 1.44 mmol of ferric acetate tetrahydrate into the liner of the reactor.

[0049] The second step is to add 10 mL of ethylene glycol solvent to the liner and stir for 1 hour.

[0050] The third step is to maintain the temperature of the hydrothermal reactor at 180℃ for 12 hours.

[0051] Fourth, after naturally cooling to ambient temperature, the nanocrystals were washed repeatedly with dilute HCl, hot water, and ethanol to remove residual reagents. The resulting nanocrystals were then dried in a vacuum oven to obtain iron phthalocyanine nanotubes.

[0052] Effect Evaluation 1

[0053] Figure 1 The image shows a SEM image of the iron phthalocyanine nanotube material in Example 1. Figure 1 It can be seen that the average length and diameter of the iron phthalocyanine nanotubes are in the range of 2-6 μm and 100-400 nm, respectively; Figure 2 The image shows a TEM image of the iron phthalocyanine nanotube material in Example 1. The interlayer spacing of the iron phthalocyanine nanotubes is 1.2 nm, which is related to the (100) plane.Figure 3 SEM image of the iron phthalocyanine nanotube material on graphene in Example 1, from Figure 3 It can be seen from the SEM image that the FePc nanotubes are actually located on the rGO nanosheets, and the rGO shows wrinkles and rough texture due to its flexible and ultra-thin characteristics; Figure 4 XRD image of the iron phthalocyanine nanotube material in Example 1, XRD crystal peaks are observed at 7.3 and 9.5, indicating β-phase FePc nanotubes.

[0054] Effect evaluation 2

[0055] 1. Configure a negatively charged electrolyte: 1 mM of K3FeC6N6 is dissolved in a 0.1 M KCl solution;

[0056] 2. Test: Three-electrode test is used, glassy carbon electrode as working electrode, silver-silver chloride as counter electrode, and mercury-mercurous sulfate as reference electrode.

[0057] 3. Take the iron phthalocyanine nanotube material and graphene with a mass ratio of 2:1, dissolve them in N,N-dimethylformamide, heat and filter, then dissolve them in isopropanol, and ultrasonically disperse them uniformly. Drop the uniformly ultrasonically dispersed solution onto the glassy carbon electrode, dry it with an infrared lamp, and then test it.

[0058] 4. Use Shanghai Chenhua CHI600E electrochemical workstation for analysis.

[0059] The Figure 5 The electrochemical performance results tested under the same conditions are as follows: conductivity: graphene > graphene and iron phthalocyanine nanotube composite material of Example 1 > iron phthalocyanine nanotube.

[0060] Effect evaluation 3

[0061] 1. Configure a 0.1 M KOH solution;

[0062] 2. Test: Three-electrode test is used, glassy carbon electrode as working electrode, graphite rod as counter electrode, and mercury-mercurous oxide as reference electrode.

[0063] 3. Take the iron phthalocyanine nanotube material and graphene with a mass ratio of 2:1, dissolve them in N,N-dimethylformamide, heat and filter, then dissolve them in isopropanol, and ultrasonically disperse them uniformly. Drop the uniformly ultrasonically dispersed solution onto the glassy carbon electrode, dry it with an infrared lamp, and then test it.

[0064] 4. Use Shanghai Chenhua CHI760E electrochemical workstation for analysis.

[0065] The Figure 6For the electrochemical performance test results, the initial potentials of graphene, iron phthalocyanine nanotube, graphene and iron phthalocyanine nanotube composite of Example 1 were +0.89, +0.75 and +0.58 V, respectively. In addition, the ORR half-wave potentials (E 1 / 2 ) were +0.98, +0.91 and +0.85 V, respectively, and the performance of graphene and iron phthalocyanine nanotube composite of Example 1 was the best.

[0066] Obviously, the above examples are merely illustrative examples for the sake of clarity, and are not intended to limit the embodiments. For those of ordinary skill in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. An electrocatalyst, characterized in that, The preparation method of the iron phthalocyanine nanotube material using iron phthalocyanine nanotubes and graphene includes the following steps: S11: Add iron salt, ligand, and ammonium molybdate to a small molecule alcohol, mix, and heat to react, obtaining the reaction product; the iron salt is ferric acetate, the ligand is phthalonitrile, the small molecule alcohol is ethanol or ethylene glycol, and the molar ratio of the ligand to the iron salt is 2-6:1; the mixing time is 10-100 min, the heating temperature is 150-200℃, and the time is 10-15 h; S12: After removing impurities from the reaction product, dry it to obtain the iron phthalocyanine nanotube material; the iron phthalocyanine nanotube material has a length of 2-6 μm and a diameter of 100-400 nm.

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