A preparation method of multidimensional carbon-based iron nanocatalyst and its products and applications

Abstract

The invention discloses a method for preparing a multidimensional carbon-based iron nanocatalyst, with polyaniline as a carrier, through planetary high-energy ball milling, the iron phthalocyanine molecule is partially destroyed, the generated fragments or degradation products are loaded in the polyaniline structure, and the fixing and dispersion effect is played, and the ethylene glycol therein is used as both abrasive and protective agent for iron fragments; the dicyandiamide added subsequently forms carbon nanotubes with iron nanoparticles during high-temperature pyrolysis, and the carbon in the iron phthalocyanine forms carbon nanosheets with dicyandiamide, forming a multidimensional carbon-based iron nanocatalyst; dicyandiamide also increases the doping amount of nitrogen in carbon nanotubes and carbon nanosheets, greatly enriching active sites such as Fe-N and Fe-N-C. The present invention is a new method for preparing a multidimensional carbon-based iron nanocatalyst, and the process is simple, the conditions are easy to control, and the product has excellent oxygen reduction reaction electrocatalytic activity, and has a wide range of application prospects in electrochemical new energy fields such as fuel cells and metal-air batteries.

Description

Technical Field

[0001] The present invention relates to the field of chemical energy materials, and in particular to a method for preparing a multidimensional carbon-based iron nanocatalyst, a product thereof and an application thereof. Background Art

[0002] Due to the continuous consumption of fossil energy and the increasing requirements of people for the environment, the development of various environmentally friendly, sustainable and low-cost new energy sources has received extensive attention from governments, scientists and technicians. Among various new energy systems, electrochemical energy has received special attention. Among them, fuel cells and metal-air batteries have shown more and more broad application prospects due to their significant advantages such as high energy conversion efficiency, high energy density, safety and reliability, and environmental friendliness. In addition, the cathode active substances of fuel cells and metal-air batteries are oxygen, which comes from the air and can be used directly, thus greatly improving the energy density of the battery. The cathode reactions of these batteries are all oxygen reduction reactions (ORR), but since ORR itself is a kinetically slow process, it requires electrocatalysts with strong catalytic activity to completely reduce oxygen to water, that is, it is a four-electron process. Among the currently known catalysts, metal platinum or platinum-based composite catalysts are the best electrocatalytic materials for ORR. They can reduce oxygen to water at a higher starting potential and higher current density, so they are also the most suitable cathode catalysts for fuel cells and metal-air batteries. However, platinum resources are scarce on Earth, their distribution is extremely uneven, and mining is extremely difficult, resulting in high costs and prices for platinum. Therefore, large-scale practical applications of platinum do not have good commercial value, which seriously limits the practical application of fuel cells and metal-air batteries.

[0003] In order to solve the problems of ORR electrocatalysts in this type of battery, the development of low-cost, non-platinum (or even non-precious metal) ORR electrocatalysts has become one of the important technical contents in the research process of these batteries. At present, people have studied and developed many non-platinum ORR electrocatalysts and have made certain progress. But in general, the preparation of these non-platinum ORR electrocatalysts generally has problems such as complex preparation process, difficulty in large-scale production and weak stability. Therefore, the development of non-platinum, simple preparation process, and new ORR electrocatalysts has very important practical value for the large-scale practical application of fuel cells and metal-air batteries. Summary of the invention

[0004] The purpose of the present invention is to provide a multidimensional carbon-based iron nanocatalyst, and the purpose of the present invention is also to provide the synthesis and application of a multidimensional carbon-based iron nanocatalyst.

[0005] To achieve the above object, the embodiment of the present invention is: a multidimensional carbon-based iron nanocatalyst, comprising the following steps:

[0006] (1) Add polyaniline powder and iron phthalocyanine into a planetary high-energy ball mill, then add grinding agate balls with a diameter of 10 mm, and finally add ethylene glycol. After mixing, seal the ball mill and continue working at a speed of 350 rpm for 16 hours. The resulting powder is catalyst precursor-1.

[0007] The mass ratio of the polyaniline powder to iron phthalocyanine is 100:10 to 60;

[0008] The mass of the ground agate balls is 80 times that of the polyaniline powder;

[0009] The volume of the ethylene glycol is based on the amount of ethylene glycol that just covers the solid.

[0010] (2) Transfer the catalyst precursor 1 to a mortar, add dicyandiamide and ethanol, and grind thoroughly to form a uniform slurry. o C, and the solid formed after sufficient grinding is catalyst precursor-2.

[0011] The mass of the dicyandiamide is 5 times the mass of the catalyst precursor-1;

[0012] The amount of ethanol is such that the ethanol just covers the solid.

[0013] (3) The catalyst precursor 2 was transferred into a boat-shaped crucible with a lid and then placed in a tube furnace. o C / min and the temperature was raised to 200 o C, keep at this temperature for 1 hour; continue to heat up to 550 o C and kept at this temperature for 2 hours; then continued to heat up to 800 o C, and keep this temperature for 2 hours; finally, cool naturally to room temperature, and the obtained black powder is the multi-dimensional carbon-based iron nanocatalyst.

[0014] A multi-dimensional carbon-based iron nanocatalyst prepared according to the method described above.

[0015] The application of the multidimensional carbon-based iron nanocatalyst prepared by the method in the electrocatalysis of oxygen reduction reaction.

[0016] The present invention uses polyaniline as a carrier, and partially destroys the iron phthalocyanine molecules through planetary high-energy ball milling. The generated fragments or degradation products are loaded in the polyaniline structure to play a fixing and dispersing role. The ethylene glycol therein serves as both a grinding agent and a protective agent for the iron fragments. The subsequently added dicyandiamide forms carbon nanotubes together with iron nanoparticles during high-temperature pyrolysis, and the carbon in the iron phthalocyanine and dicyandiamide form carbon nanosheets together, thereby forming a multidimensional carbon-based iron nanocatalyst. Dicyandiamide also increases the doping amount of nitrogen in the carbon nanotubes and carbon nanosheets, thereby greatly enriching active sites such as Fe-N and Fe-NC. The present invention is a new method for preparing a multidimensional carbon-based iron nanocatalyst, the process is simple, the conditions are easy to control, and the product has excellent electrocatalytic activity for oxygen reduction reaction, and has a wide range of application prospects in electrochemical new energy fields such as fuel cells and metal-air batteries. DETAILED DESCRIPTION

[0017] Example 1

[0018] A method for preparing a multidimensional carbon-based iron nanocatalyst comprises the following steps:

[0019] (1) Add 500 g of polyaniline powder and 50 g of iron phthalocyanine into a planetary high-energy ball mill, then add 40 g of grinding agate balls with a diameter of 10 mm, and finally add ethylene glycol so that the ethylene glycol just covers the solid. After mixing, seal the ball mill and continue to operate at a rotation speed of 350 rpm for 16 hours. The resulting powder is catalyst precursor-1.

[0020] (2) Transfer the above catalyst precursor-1 into a mortar, add 2.6 g of dicyandiamide, and add an appropriate amount of ethanol to cover the solid, grind it thoroughly to form a uniform slurry, and then slurry the slurry at 60 o C, and the solid formed after sufficient grinding is catalyst precursor-2.

[0021] (3) The catalyst precursor 2 was transferred into a boat-shaped crucible with a lid and then placed in a tube furnace. o C / min and the temperature was raised to 200 o C, keep at this temperature for 1 hour; continue to heat up to 550 o C and kept at this temperature for 2 hours; then continued to heat up to 800 o C, and keep this temperature for 2 hours; finally, cool naturally to room temperature, and the obtained black powder is the multi-dimensional carbon-based iron nanocatalyst.

[0022] (4) Using platinum as the counter electrode and Ag / AgCl (sat. KCl) as the reference electrode, the multidimensional carbon-based iron nanocatalyst was coated on the surface of a rotating glassy carbon electrode as the working electrode. In a three-electrode system, the electrocatalytic activity of the multidimensional carbon-based iron nanocatalyst for oxygen reduction reaction (ORR) was measured in the following different oxygen-saturated electrolyte solutions. The results are as follows:

[0023]

[0024] Example 2

[0025] A method for preparing a multidimensional carbon-based iron nanocatalyst comprises the following steps:

[0026] (1) Add 500 g of polyaniline powder and 150 g of iron phthalocyanine into a planetary high-energy ball mill, then add 40 g of grinding agate balls with a diameter of 10 mm, and finally add ethylene glycol so that the ethylene glycol just covers the solid. After mixing, seal the ball mill and continue to operate at a rotation speed of 350 rpm for 16 hours. The resulting powder is catalyst precursor-1.

[0027] (2) Transfer the above catalyst precursor-1 into a mortar, add 3.5 g of dicyandiamide, and add an appropriate amount of ethanol to cover the solid, grind it thoroughly to form a uniform slurry, and then slurry the slurry at 60 o C, and the solid formed after sufficient grinding is catalyst precursor-2.

[0028] (3) The catalyst precursor 2 was transferred into a boat-shaped crucible with a lid and then placed in a tube furnace. o C / min and the temperature was raised to 200 o C, keep at this temperature for 1 hour; continue to heat up to 550 o C and kept at this temperature for 2 hours; then continued to heat up to 800 o C, and keep this temperature for 2 hours; finally, cool naturally to room temperature, and the obtained black powder is the multi-dimensional carbon-based iron nanocatalyst.

[0029] (4) Using platinum as the counter electrode and Ag / AgCl (sat. KCl) as the reference electrode, the multidimensional carbon-based iron nanocatalyst was coated on the surface of a rotating glassy carbon electrode as the working electrode. In a three-electrode system, the electrocatalytic activity of the multidimensional carbon-based iron nanocatalyst for oxygen reduction reaction (ORR) was measured in the following different oxygen-saturated electrolyte solutions. The results are as follows:

[0030]

[0031] Example 3

[0032] A method for preparing a multidimensional carbon-based iron nanocatalyst comprises the following steps:

[0033] (1) Add 500 g of polyaniline powder and 300 g of iron phthalocyanine into a planetary high-energy ball mill, then add 40 g of grinding agate balls with a diameter of 10 mm, and finally add ethylene glycol so that the ethylene glycol just covers the solid. After mixing, seal the ball mill and continue to operate at a rotation speed of 350 rpm for 16 hours. The resulting powder is catalyst precursor-1.

[0034] (2) Transfer the above catalyst precursor-1 into a mortar, add 4.0 g of dicyandiamide, and add an appropriate amount of ethanol to cover the solid, grind it thoroughly to form a uniform slurry, and then slurry the slurry at 60 o C, and the solid formed after sufficient grinding is catalyst precursor-2.

[0035] (3) The catalyst precursor 2 was transferred into a boat-shaped crucible with a lid and then placed in a tube furnace. o C / min and the temperature was raised to 200 o C, keep at this temperature for 1 hour; continue to heat up to 550 o C and kept at this temperature for 2 hours; then continued to heat up to 800 o C, and keep this temperature for 2 hours; finally, cool naturally to room temperature, and the obtained black powder is the multi-dimensional carbon-based iron nanocatalyst.

[0036] (4) Using platinum as the counter electrode and Ag / AgCl (sat. KCl) as the reference electrode, the multidimensional carbon-based iron nanocatalyst was coated on the surface of a rotating glassy carbon electrode as the working electrode. In a three-electrode system, the electrocatalytic activity of the multidimensional carbon-based iron nanocatalyst for oxygen reduction reaction (ORR) was measured in the following different oxygen-saturated electrolyte solutions. The results are as follows:

[0037]

[0038] The present invention proposes a new method for synthesizing a multidimensional carbon-based iron nanocatalyst in a simple manner, and realizes the simple synthesis of a multidimensional carbon-based iron nanocatalyst by combining a planetary high-energy ball milling process with a high-temperature pyrolysis process. In the planetary high-energy ball milling process, polyaniline nanoparticles are used as carriers, and the iron phthalocyanine molecules are partially destroyed by ball milling, and the generated fragments or degradation products are loaded in the polyaniline structure to play a fixing and dispersing role. The ethylene glycol therein serves as both an abrasive and a protective agent, isolating the iron fragments from contact with moisture in the air, fully ensuring that the iron fragments do not agglomerate and can be fully dispersed on the polyaniline; then dicyandiamide is added, and the mixture is then subjected to a segmented high-temperature pyrolysis treatment, and finally iron nanoparticles loaded with a multidimensional carbon composite in which carbon nanosheets and carbon nanotubes coexist are formed. Phthalocyanine iron is partially decomposed into small iron-containing fragment intermediates under high-energy ball milling. In the subsequent high-temperature pyrolysis process, iron nanoparticles and dicyandiamide form carbon nanotubes, and carbon in phthalocyanine iron and dicyandiamide form carbon nanosheets together, thereby forming a multi-dimensional carbon-based iron nanocatalyst in which carbon nanotubes and carbon nanosheets coexist; dicyandiamide not only plays a template role in the formation of carbon nanotubes, but also the nitrogen-containing small molecules or groups produced by the decomposition of dicyandiamide in the pyrolysis process are combined with carbon, increasing the nitrogen doping amount in carbon nanotubes and carbon nanosheets, thereby greatly enriching active sites such as Fe-N and Fe-NC. The synthesis process of the multi-dimensional carbon-based iron nanocatalyst of the present invention is simple, and the iron nanoparticles therein have the characteristics of small particle size, uniform distribution, strong stability, etc., and have excellent electrocatalytic activity for ORR in a full range of pH solutions including acidic, neutral and alkaline.

Claims

1. A method for preparing a multidimensional carbon-based iron nanocatalyst, characterized in that The following steps are involved: (1) Add polyaniline powder and iron phthalocyanine into a planetary high-energy ball mill, then add grinding agate balls with a diameter of 10 mm, and finally add ethylene glycol. After mixing, seal the ball mill and continue to work at a speed of 350 rpm for 16 hours. The resulting powder is catalyst precursor-1; The mass ratio of the polyaniline powder to iron phthalocyanine is 100:10 to 60; The mass of the ground agate balls is 80 times that of the polyaniline powder; The volume of the ethylene glycol is based on the amount of ethylene glycol just covering the solid; (2) Transfer the catalyst precursor 1 to a mortar, add dicyandiamide and ethanol, and grind thoroughly to form a uniform slurry. o C, and the solid formed after being fully ground and uniformly obtained is catalyst precursor-2; The mass of the dicyandiamide is 5 times the mass of the catalyst precursor-1; The amount of ethanol is such that the ethanol just covers the solid; (3) The catalyst precursor 2 is transferred into a boat-shaped crucible with a lid, and then placed in a tube furnace. Under nitrogen atmosphere, firstly o C / min and the temperature was raised to 200 o C, keep at this temperature for 1 hour; continue to heat up to 550 o C and kept at this temperature for 2 hours; then continued to heat up to 800 o C, and keep this temperature for 2 hours; finally, cool naturally to room temperature, and the obtained black powder is the multi-dimensional carbon-based iron nanocatalyst.

2. The method for preparing the multidimensional carbon-based iron nanocatalyst according to claim 1, characterized in that The mass ratio of the polyaniline powder to iron phthalocyanine is 100:

30.

3. A multidimensional carbon-based iron nanocatalyst prepared according to the method of claim 1.

4. Application of the multidimensional carbon-based iron nanocatalyst prepared by the method as claimed in claim 1 in electrocatalysis of oxygen reduction reaction.

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