CN110137516B - Iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst and preparation method thereof - Google Patents

Abstract

The invention discloses an iron-tin alloy loadA sulfur and nitrogen co-doped carbon electrocatalyst and a preparation method belong to the field of preparation of battery cathode oxygen reduction catalysts. The invention adopts doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenyl porphyrin and 2, 6-diformaldehyde pyridine at 60 ℃ under the protection of nitrogen, glacial acetic acid (analytically pure) is used as a catalyst, and anhydrous FeCl is added₃As a metal source, synthesizing a covalent organic polymer loaded by Sn-Fe, and preparing FeSn after pyrolysis at high temperature₂An alloy-supported carbon material. The novel iron-tin alloy supported carbon-based electrocatalyst with the double-shell structure has a two-dimensional porous structure, a P area nonmetal tin catalysis strategy is promoted by adopting metal iron, the metal oxide middle layer provides a good channel for charge transfer and transfer in a system, and the mass transfer process is accelerated, so that a new idea is provided for developing a P area non-noble metal oxygen reduction electrocatalyst, the preparation process is simple and feasible, and the large-scale industrial application is easy to realize.

Description

Iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst and preparation method thereof

Technical Field

The invention relates to the technical field of oxygen reduction catalysts of battery cathodes, in particular to an iron-tin alloy nanoparticle loaded sulfur-nitrogen co-doped carbon electrocatalysis material with a double-shell structure derived from a covalent porphyrin-based skeleton, namely an iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalysis material and a preparation method thereof.

Background

In order to efficiently solve the increasing contradiction between economic development and energy shortage and environmental pollution, the development of clean, efficient, renewable energy storage and conversion technologies (e.g. proton exchange membrane fuel cells, zinc air cells) has become a very urgent task. The slow rate of oxygen reduction at the cathode of the cell limits the power output of the fuel cell, preventing large-scale commercial use of such cells. Therefore, the search for a cathode electrocatalyst that enhances the rate of oxygen reduction reactions, improving the efficient conversion of chemical energy to electrical energy, has been the focus of research. In general, a large number of Pt-based electrocatalysts are popular because of their low overpotentials, but the Pt noble metal resources are scarce, expensive and susceptible to poisoning, so that the commercialization of fuel cells is greatly hindered. The development of new oxygen-reduced non-noble metal or non-noble metal oxide electrocatalysts (especially non-toxic, low cost P-block metals) to completely replace Pt-based catalytic materials has become a research hotspot in recent years.

At present, tin-based oxygen reduction electrocatalysts are widely considered as a promising electrode material due to the characteristics of high electron mobility, excellent conductivity, long-term chemical stability and environmental friendliness. Such as Pt-Sn, Au-Sn, Pd-Sn alloys, etc., have been used as oxygen-reducing electrocatalytic materials for catalyzing ORR in alkaline media. Despite the tremendous efforts, reducing the noble metal content remains a challenge to increase electrocatalytic activity due to the limitations of noble metals. The search for transition metal-tin based electrocatalysts to completely replace noble metal-tin based catalytic materials has been a major task of research. Covalent organic backbones (COFs) stand out in many materials with large specific surface area and rich pore structure due to their two-or three-dimensional spatial structure, which avoids the aggregation of active components and effectively increases the active site density. The lower skeleton density can be generated simultaneously with the active material as the carbon carrier, and the composition and the structure of COFs can be adjusted to promote the molecular generation and the functional adjustment of the catalytic material. Thus, FeSn is prepared using a two-dimensional covalent organic polymer as host material₂Alloy-supported oxygen reduction electrocatalysts have been the focus of research for improving oxygen reduction catalytic activity and for use in zinc-air batteries and other fields.

Disclosure of Invention

The invention aims to provide an iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst and a preparation method thereof aiming at the defects of the prior artThe invention adopts Sn (OH)_xUnder the protection of nitrogen at 60 ℃, glacial acetic acid (analytically pure) is used as a catalyst, anhydrous ferric chloride is added, a covalent organic polymer doped with Fe and Sn metal is synthesized through Schiff base coupling reaction by using doped 5, 10, 15, 20-tetra (amino) phenylporphyrin and 2, 6-diformylpyridine, and the electrocatalyst of the iron-tin alloy loaded sulfur-nitrogen co-doped carbon is prepared after high-temperature pyrolysis. The construction of the molecular structure of the high-efficiency derived tin-based non-noble metal oxygen reduction electrocatalyst is realized, the dependence of the electrocatalyst on noble metals or noble metal alloys is broken through, and the density of active sites of sulfur-nitrogen doped carbon in a porous material is effectively increased by virtue of a two-dimensional pore channel structure with rich covalent organic frameworks, so that the oxygen reduction activity is improved, and a foundation is laid for the synthesis of a self-supported high-efficiency and stable main group non-noble metal-sulfur-nitrogen co-doped carbon oxygen reduction electrocatalyst.

The specific technical scheme for realizing the purpose of the invention is as follows:

a preparation method of an iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst comprises the following specific steps:

step 1: preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrins

Mixing p-nitrobenzaldehyde and pyrrole according to a molar ratio of 1: 2-4, adding into boiled analytically pure propionic acid with a volume ratio of 100-150, refluxing for 1h at the temperature of 130 ℃, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum; then refluxing and washing with pyridine, cooling overnight, carrying out suction filtration, then washing with analytically pure acetone until the filtrate is colorless, and carrying out vacuum drying to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin;

step 2: preparation of doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrins of (1)

Under the protection of nitrogen, taking the prepared 5, 10, 15, 20-tetra (amino) phenyl porphyrin and SnCl₂·2H₂Mixing O according to the molar ratio of 1: 8-10, dissolving the mixture by using concentrated HCl, stirring the mixture for 2.5 hours at room temperature, heating the mixture to 70 ℃, reacting the mixture for 30 minutes, cooling the mixture in an ice-water bath after the reaction is finished, pouring 5-10 volume ratio of deionized water, adjusting the pH value to 8-9, and performing suction filtration to obtain the doped Sn (OH)_x5, 10, 15, 20-four(amino) phenyl porphyrins; wherein X is 2 or 4;

and step 3: preparation of covalent Metal-organic polymers

Weighing doped Sn (OH) under the protection of nitrogen_xMixing and dissolving 5, 10, 15, 20-tetra (amino) phenyl porphyrin, 2, 6-dimethyl pyridine and anhydrous ferric chloride in dimethyl sulfoxide according to the molar ratio of 1: 4-5: 1-3, using glacial acetic acid as a catalyst, heating and refluxing for 15h at 60 ℃, washing the filtered solid with analytically pure methanol until the filtrate is colorless after the reaction is finished, and obtaining brick red solid, namely covalent metal organic polymer;

and 4, step 4: preparation of alloy-loaded covalent organic polymers

Under the protection of nitrogen, carrying out pyrolysis treatment on the prepared covalent metal organic polymer at the temperature of 800-1000 ℃ and the heating rate of 2-5 ℃/min for 4h, and preparing the iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst.

An iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst prepared by the method.

The invention successfully prepares the iron-tin alloy loaded carbon fuel cell cathode electrocatalyst with low cost and high activity, the novel microporous structure has larger pore volume and narrower pore size distribution, the active sites are uniformly distributed, the electrochemical performance of the material is improved, and the electrocatalyst shows higher catalytic activity and stability. The special double-shell structure wrapped by the carbon layer and the oxide layer greatly improves the stability of the material and promotes the transfer of electrons in the electrocatalysis process. The electrocatalyst of the invention also shows higher open circuit potential and better stability in zinc-air batteries. The invention provides a new idea for developing a p-region non-noble metal electrocatalyst.

Drawings

FIG. 1 shows Sn (OH) in example 1 of the present invention_xInfrared spectrograms of @ TAPP and Fe-Sn-CPFs;

FIG. 2 shows FeSn in example 1 of the present invention₂/FeSnO_xLinear scan plot of @ S-N-C-1000;

FIG. 3 shows FeSn in example 2 of the present invention₂@FeSnO_xLinear scan plot of @ S-N-C-800;

FIG. 4 shows FeSn in example 3 of the present invention₂@FeSnO_xA high angle X-ray powder diffraction pattern of @ S-N-C-800;

FIG. 5 shows FeSn in example 4 of the present invention₂@FeSnO_xThe nitrogen adsorption and desorption curve chart and the aperture distribution chart of @ S-N-C-1000;

FIG. 6 shows FeSn in example 5 of the present invention₂@FeSnO_xLinear scan plot of @ S-N-C-900;

FIG. 7 shows FeSn in example 6 of the present invention₂@FeSnO_xTransmission electron micrographs of @ S-N-C-900;

FIG. 8 shows FeSn in example 7 of the present invention₂@FeSnO_xRaman spectrum of @ S-N-C-900;

FIG. 9 shows FeSn in example 8 of the present invention₂@FeSnO_xThe nitrogen adsorption and desorption curve chart and the aperture distribution chart of @ S-N-C-800;

FIG. 10 shows FeSn in example 9 of the present invention₂@FeSnO_xThe charge-discharge performance curve and the stability chart of the zinc-air battery of @ S-N-C-900.

Detailed Description

The invention is described in detail below with reference to the drawings and examples.

The synthesis process of the electrocatalyst of the invention is shown as follows:

example 1

a. Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrins

0.1mol of p-nitrobenzaldehyde was added to 100mL of boiled propionic acid (analytical grade) and stirred for 30min, 10mL of propionic acid containing 0.2mol of pyrrole were added dropwise and refluxed at 130 ℃ for 1h, and the product filtered off after the end of the reaction was washed thoroughly with deionized water and dried in vacuo. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Preparation of doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrins of (1)

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 100mL of concentrated hydrochloric acid (analytically pure) to obtain 0.8 mol of SnCl₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 50mL H₂In a beaker of O, the pH was adjusted to 8 to 9, and 5.5 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent Metal-organic polymers

Weighing 0.1mol of doped Sn (OH) under the protection of nitrogen_xMixing and dissolving 5, 10, 15, 20-tetra (amino) phenyl porphyrin, 0.4 mol of 2, 6-diformylpyridine and 0.3mol of anhydrous ferric chloride in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing at 60 ℃ for 12 hours, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain brick red solid covalent metal organic polymers Fe-Sn-CPFs;

d. preparation of alloy-loaded covalent organic polymers

Under the protection of nitrogen, carrying out pyrolysis treatment on the prepared covalent metal organic polymer at the temperature of 1000 ℃, at the heating rate of 3 ℃/min and under the heat preservation for 4 hours to prepare the FeSn alloy loaded sulfur-nitrogen co-doped carbon electrocatalytic FeSn₂@FeSnO_x@S-N-C-1000。

0.1 molar doped Sn (OH) prepared as described above with reference to FIG. 1_x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@ TAPP) and covalent metal organic frameworks (Fe-Sn-CPFs) are detected by infrared detection and are known to be 3380cm^-1The nearby double absorption peak is NH on the skeleton₂1280cm of telescopic vibration^-1The absorption peak of (1) is C-N stretching vibration of benzene ring and amino group at 1600cm^-1,1500cm^-1The clear infrared absorption peak shows the synthesis of main skeletons of phenyl and pyrrole in TAPP. Simultaneously, infrared detection is carried out on the prepared covalent organic polymer skeleton, and the detection result shows that the thickness of the covalent organic polymer skeleton is 3380cm^-1The appearance of double peaks disappeared at 1709cm^-1And 1400cm^-1The absorption peaks of stretching vibration of C ═ N and C-C ═ N-C appear, indicating that 5, 10, 15, 20-tetra (amino) phenylporphyrin was successfully polymerized with 2, 6-diformaldehyde pyridine.

FeSn prepared by the method₂@FeSnO_x@ S-N-C-1000 electrocatalytic material electrochemical activity tests were performed at CHI760C electrochemical workstation using Cyclic Voltammetry (CV) and rotating disk electrode technology. The test adopts a three-electrode system, a glassy carbon electrode with the diameter of 3mm is taken as a working electrode, Ag/AgCl (3MKCl) is taken as a reference electrode, a Pt wire is taken as a counter electrode, and 0.1MKOH solution is taken as electrolyte. Polishing the metallographic abrasive paper for the working electrode and then using Al₂O₃Polishing, ultrasonic cleaning with ethanol and deionized water, air drying under infrared lamp, and collecting 10mg of the FeSn₂@FeSnO_xAdding the @ S-N-C-1000 electrocatalyst into a mixed solution of 30uL Nafion and 1.25mL of ethanol for ultrasonic treatment, uniformly coating the obtained uniformly dispersed mixed solution on a polished working electrode, volatilizing the solvent under an infrared lamp to obtain a glassy carbon electrode with a FeSn-coated surface layer₂@FeSnO_xA working electrode of @ S-N-C-1000 electrocatalyst thin film. High-purity nitrogen or oxygen is respectively introduced for 15min before the test to ensure that the gas in the electrolyte reaches a saturated state, and scanning is carried out at the room temperature at the speed of 50 mV/s.

FeSn prepared as described above with reference to FIG. 2₂@FeSnO_xElectrochemical testing of @ S-N-C-1000 electrocatalyst and commercial platinum carbon, FeSn₂@FeSnO_xThe half-wave potential of @ S-N-C-1000 was 0.80V, but was 60mV lower than that of platinum carbon, respectively. Description although FeSn₂@FeSnO_xThe catalytic activity of @ S-N-C-1000 is inferior to that of platinum carbon, but FeSn₂The doping of the alloy greatly improves the catalytic performance of the catalytic material.

Example 2

a. Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrins

Adding 0.1mol of p-nitrobenzaldehyde into 120mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.3mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Preparation of doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrins of (1)

Taking 0.1mol of the doped Sn (OH) prepared in the previous step under the protection of nitrogen _x5, 10, 15, 20-tetra (amino) phenylporphyrin and 0.9 mol SnCl₂·2H₂O mixing, dissolving with concentrated hydrochloric acid (analytically pure), stirring at room temperature for 2.5 hours, heating to 70 ℃, reacting for 30 minutes, cooling in ice-water bath after the reaction is finished, pouring 100ml of deionized water, adjusting pH to 8-9, and performing suction filtration to obtain 6.7 g of doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrin;

c. preparation of covalent Metal-organic polymers

Weighing 0.1mol of doped Sn (OH) under the protection of nitrogen_xMixing and dissolving 5, 10, 15, 20-tetra (amino) phenyl porphyrin, 0.4 mol of 2, 6-diformylpyridine and 0.2mol of anhydrous ferric chloride in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing for 13 hours at 60 ℃, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain brick red solid, namely the covalent metal organic polymer Fe-Sn-CPFs;

d. preparation of alloy-loaded sulfur-nitrogen-doped carbon electrocatalyst

Under the protection of nitrogen, grinding the prepared covalent metal organic polymer, heating to 800 ℃ at a heating rate of 2 ℃/min under the atmosphere of high-purity nitrogen, preserving heat for 4 hours, and cooling to obtain the iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst (FeSn)₂@FeSnO_x@S-N-C-800)。

FeSn prepared as described above with reference to FIG. 3₂@FeSnO_xElectrochemical testing of the @ S-N-C-800 electrocatalyst, FeSn₂@FeSnO_xHalf of an @ S-N-C-800 electrocatalystThe wave potential is 0.82V, which shows that the material still has good catalytic activity at the heat treatment temperature of 800 ℃.

Example 3

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 150mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.3mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 1.0 mol of SnCl in 100mL of concentrated hydrochloric acid (analytically pure)₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In a beaker of O, the pH was adjusted to 8 to 9, and 7.0 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent organic polymers Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_xMixing and dissolving @ TAPP and 0.5 mol of 2, 6-dimethyl aldehyde pyridine in dimethyl sulfoxide (analytically pure), adding 0.1mol of anhydrous FeCl as a catalyst and using glacial acetic acid (analytically pure)₃And heating and refluxing for 14h at 60 ℃, and after the reaction is finished, washing the filtered solid by using methanol (analytically pure) until the filtrate is colorless to obtain the Fe-Sn-CPFs.

d.FeSn₂@FeSnO_xPreparation of @ S-N-C-800 electrocatalyst.

Grinding the prepared Fe-Sn-CPFs electro-catalytic material, respectively heating to 800 ℃ at the speed of 2 ℃/min under the atmosphere of high-purity nitrogen for heat treatment for 4 hours, and cooling to room temperature to obtain FeSn₂@FeSnO_x@ S-N-C-800 catalytic material.

FeSn prepared as described above with reference to FIG. 4₂@FeSnO_xX-ray diffraction test of @ S-N-C-800 electrocatalyst shows that the diffraction peak of graphitic carbon appears at 2 θ ═ 26.5 °, corresponding to (002) crystal plane of graphitic carbon, and the diffraction peaks appearing at 2 θ ═ 33 ° (002),35 ° (211),39.1 ° (112),43.8 ° (310),61.1 ° (411),67.3 ° (402), and 71 ° (004) correspond to FeSn₂(PDF #73-2030) and Fe₄C (PDF #65-3286) which proves that FeSn exists in the prepared material₂And Fe₄The presence of the C crystalline phase provides the active sites for the electrocatalytic properties of the material.

Example 4

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 140mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.4 mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Preparation of Sn (OH) x doped 5, 10, 15, 20-tetra (amino) phenylporphyrins

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 1.0 mol of SnCl in 100mL of concentrated hydrochloric acid (analytically pure)₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂Adjusting the pH value to 8-9 in a beaker of O, and performing suction filtration to obtain doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@ TAPP)6.9 grams.

c. Preparation of covalent organic polymers Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_xMixing @ TAPP with 0.5 mol of 2, 6-diformaldehyde pyridine and dissolving in dimethylIn the basic sulfoxide (analytically pure), glacial acetic acid (analytically pure) is used as a catalyst, 0.2mol of anhydrous ferric chloride is added, heating and refluxing are carried out for 15h at 60 ℃, and after the reaction is finished, the filtered solid is washed by methanol (analytically pure) until the filtrate is colorless, so that the Fe-Sn-CPFs is prepared.

d.FeSn₂@FeSnO_xPreparation of @ S-N-C-1000 catalytic material

Grinding the prepared Fe-Sn-CPFs electro-catalytic material, heating to 1000 ℃ respectively at 2 ℃/min under a high-purity nitrogen atmosphere for heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn serving as the covalent metal organic polymer₂@FeSnO_x@ S-N-C-1000 catalytic material.

FeSn prepared as described above with reference to FIG. 5₂@FeSnO_xThe @ S-N-C-1000 electrocatalyst is subjected to a nitrogen adsorption and desorption test, and FeSn is known from a test spectrogram₂@FeSnO_xThe @ S-N-C-1000 conforms to a typical first-class adsorption isotherm and has the characteristics of a typical microporous material and the BET specific surface value of 602m²g^-1The pore diameter of the micropores is distributed at about 0.45 nm.

Example 5

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 150mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.2mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 1.0 mol of SnCl in 100mL of concentrated hydrochloric acid (analytically pure)₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In O beakerThe pH is adjusted to 8-9 and 8.5 g of doped Sn (OH) are obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent organic polymers

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_xMixing and dissolving @ TAPP and 0.4 mol of 2, 6-dimethyl aldehyde pyridine in dimethyl sulfoxide (analytically pure), adding 0.3mol of anhydrous FeCl as a catalyst by using glacial acetic acid (analytically pure)₃And heating and refluxing for 16h at 60 ℃, and after the reaction is finished, washing the filtered solid by using methanol (analytically pure) until the filtrate is colorless to obtain the Fe-Sn-CPFs.

d.FeSn₂@FeSnO_xPreparation of @ S-N-C-900 catalytic material

Grinding the prepared Fe-Sn-CPFs electro-catalytic material, heating to 900 ℃ at the speed of 2 ℃/min under the atmosphere of high-purity nitrogen for heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn serving as the covalent metal organic polymer₂@FeSnO_x@ S-N-C-900 catalytic material.

FeSn prepared as described above with reference to FIG. 6₂@FeSnO_xElectrochemical testing of the @ S-N-C-900 electrocatalyst, FeSn₂@FeSnO_xThe half-wave potential of @ S-N-C-900 is 0.88V, which is 20mV higher than that of commercial platinum carbon, which indicates FeSn₂The alloy is used as an active center of the material to improve the oxygen reduction electrocatalytic performance.

Example 6

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 110mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.2mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished with deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Taking 0.1 mole of 5, 10 of the above synthesis under the protection of nitrogen,15, 20-Tetrakis (nitro) phenylporphyrin dissolved in 100mL of concentrated HCl, 0.9 mol of SnCl₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid, dropwise adding into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In a beaker of O, the pH was adjusted to 8 to 9, and 7.2 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent organic polymers Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_x@ TAPP, 0.4 moles of 2, 6-dicarboxylpyridine, 0.3 moles of anhydrous FeCl₃Mixing and dissolving in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing for 18h at 60 ℃, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain the covalent organic polymer Fe-Sn-CPFs material.

d.FeSn₂@FeSnO_xPreparation of the @ S-N-C-900 electrocatalyst.

Grinding the prepared Fe-Sn-CPFs material, heating to 900 ℃ at the speed of 2 ℃/min under the atmosphere of high-purity nitrogen, carrying out heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn which is the covalent organic metal organic polymer₂@FeSnO_x@ S-N-C-900 catalytic material.

FeSn prepared as described above with reference to FIG. 7₂@FeSnO_xThe morphology of the @ S-N-C-900 catalytic material is characterized by a transmission electron microscope, and the iron-tin alloy nano particles can be observed to be uniformly distributed on the carbon layer, which shows that the uniform distribution of active sites is more favorable for improving the electrocatalytic performance and stability of the material.

Example 7

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 140mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.1mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 100mL of concentrated hydrochloric acid (analytically pure), and 1mol of SnCl₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In a beaker of O, the pH was adjusted to 8 to 9, and 8.2 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Covalent organic polymers^0.3Preparation of Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_x@ TAPP, 0.5 moles of 2, 6-dicarboxylpyridine, 0.2 moles of anhydrous FeCl₃Mixing and dissolving in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing for 19h at 60 ℃, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain the covalent organic polymer Fe-Sn-CPFs material.

d.FeSn₂@FeSnO_xThe preparation of the @ S-N-C-900 catalytic material.

Grinding the prepared Fe-Sn-CPFs material, heating to 900 ℃ respectively at 2 ℃/min under a high-purity nitrogen atmosphere for heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn covalent organic metal organic polymer₂@FeSnO_x@ S-N-C-900 catalytic material.

FeSn prepared as described above with reference to FIG. 8₂@FeSnO_xThe Raman test of the @ S-N-C-900 electro-catalytic material is carried out, and the spectrogram shows that the thickness of the material is 2800cm^-1A 2D broad peak of graphitic carbon appears, and I_D/I_GThe value of (a) is 0.94, indicating that the material has a certain degree of graphitization, which can be confirmed by XRD results.

Example 8

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 150mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.3mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 100mL of concentrated hydrochloric acid (analytically pure), and 0.8 mol of SnCl₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In a beaker of O, the pH was adjusted to 8 to 9, and 6.9 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent organic polymers Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_x@ TAPP, 0.5 moles of 2, 6-dicarboxylpyridine, 0.3 moles of anhydrous FeCl₃Mixing and dissolving in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing for 16h at 60 ℃, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain the covalent organic polymer Fe-Sn-CPFs material.

d.FeSn₂@FeSnO_xThe preparation of the @ S-N-C-800 catalytic material.

Grinding the prepared Fe-Sn-CPFs material, heating to 800 ℃ respectively at 2 ℃/min under a high-purity nitrogen atmosphere for heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn covalent organic metal organic polymer₂@FeSnO_x@ S-N-C-800 catalytic material.

With reference to fig. 9, forFeSn prepared as described above₂@FeSnO_xThe @ S-N-C-800 electrocatalyst is subjected to a nitrogen adsorption and desorption test, and FeSn is known from a test spectrogram₂@FeSnO_x@ S-N-C-800 conforms to a typical adsorption isotherm of the first class and is characteristic of microporous materials with a BET specific surface value of 936m²g^-1The pore diameter of the micropores is distributed at about 0.38 nm.

Example 9

Preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrin

Adding 0.1mol of p-nitrobenzaldehyde into 150mL of boiled propionic acid, stirring for 30min, dropwise adding 10mL of propionic acid containing 0.2mol of pyrrole, refluxing at 130 ℃ for 1h, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum. Then refluxing and washing with pyridine, cooling overnight, filtering, washing with acetone (analytically pure) until the filtrate is colorless, and drying in vacuum to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin (TNPP).

b. Doped with Sn (OH)_xPreparation of 5, 10, 15, 20-tetra (amino) phenylporphyrin

Under the protection of nitrogen, 0.1mol of 5, 10, 15, 20-tetra (nitro) phenylporphyrin synthesized above is dissolved in 150mL of concentrated hydrochloric acid (analytically pure), and 0.8 mol of SnCl₂·2H₂Dissolving O in 25mL concentrated hydrochloric acid (analytically pure), adding dropwise into the above system, stirring at room temperature for 2.5H, heating to 70 deg.C, reacting for 30min, cooling in ice water bath, and pouring 100mL H solution₂In a beaker of O, the pH was adjusted to 8 to 9, and 7.5 g of doped Sn (OH) was obtained by suction filtration _x5, 10, 15, 20-tetra (amino) phenylporphyrin (Sn (OH))_x@TAPP)。

c. Preparation of covalent organic polymers Fe-Sn-CPFs

0.1mol of Sn (OH) prepared as described above was weighed out under nitrogen protection_x@ TAPP, 0.3 moles of 2, 6-dicarboxylpyridine, 0.3 moles of anhydrous FeCl₃Mixing and dissolving in dimethyl sulfoxide (analytically pure), using glacial acetic acid (analytically pure) as a catalyst, heating and refluxing for 20h at 60 ℃, and after the reaction is finished, washing the filtered solid with methanol (analytically pure) until the filtrate is colorless to obtain the covalent organic polymer Fe-Sn-CPFs material.

d.FeSn₂@FeSnO_xPreparation of @ S-N-C-900

Grinding the prepared Fe-Sn-CPFs material, heating to 900 ℃ respectively at 2 ℃/min under a high-purity nitrogen atmosphere for heat treatment for 4 hours, and cooling to room temperature to obtain the FeSn covalent organic metal organic polymer₂@FeSnO_x@ S-N-C-900 catalytic material.

FeSn prepared by the method₂@FeSnO_xThe @ S-N-C-900 catalytic material was assembled into a rechargeable discharge zinc-air battery as follows. By mixing the catalyst (with a loading of 4mg cm)^-2) And dispersed on a carbon cloth to prepare an air cathode. A 6 molar potassium hydroxide solution containing 0.2 molar zinc acetate was prepared as the electrolyte using polished zinc foil as the anode. Discharge polarization and power density were plotted by recording constant temperature discharge-charge cycle curves at room temperature. One cycle comprises a discharge step and a charge step (20mA cm) with the same current density and duration^-2For 24 hours, cycle 10 minutes).

FeSn prepared as described above with reference to FIG. 10₂@FeSnO_xThe @ S-N-C-900 catalytic material was tested in a zinc air cell and, as shown, exhibited an open circuit potential of 1.49V and a power density superior to that of platinum carbon. The electrocatalytic material has excellent practical application performance.

Claims (2)

1. A preparation method of an iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst is characterized by comprising the following specific steps:

step 1: preparation of 5, 10, 15, 20-tetra (nitro) phenylporphyrins

Mixing p-nitrobenzaldehyde and pyrrole according to a molar ratio of 1: 2-4, adding into boiled analytically pure propionic acid with a volume ratio of 100-150, refluxing for 1h at the temperature of 130 ℃, fully washing a filtered product after the reaction is finished by deionized water, and drying in vacuum; then refluxing and washing with pyridine, cooling overnight, carrying out suction filtration, then washing with analytically pure acetone until the filtrate is colorless, and carrying out vacuum drying to obtain 5, 10, 15, 20-tetra (nitro) phenyl porphyrin;

step 2: preparation of dopeSn(OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrins of (1)

Under the protection of nitrogen, taking the prepared 5, 10, 15, 20-tetra (nitro) phenyl porphyrin and SnCl₂·2H₂Mixing O according to the molar ratio of 1: 8-10, dissolving the mixture by using concentrated HCl, stirring the mixture for 2.5 hours at room temperature, heating the mixture to 70 ℃, reacting the mixture for 30 minutes, cooling the mixture in an ice-water bath after the reaction is finished, pouring 5-10 volume ratio of deionized water, adjusting the pH value to 8-9, and performing suction filtration to obtain the doped Sn (OH)_x5, 10, 15, 20-tetra (amino) phenylporphyrin; wherein X =2 or 4;

and step 3: preparation of covalent Metal-organic polymers

Weighing doped Sn (OH) under the protection of nitrogen_xMixing and dissolving 5, 10, 15, 20-tetra (amino) phenyl porphyrin, 2, 6-dimethyl pyridine and anhydrous ferric chloride in dimethyl sulfoxide according to the molar ratio of 1: 4-5: 1-3, using glacial acetic acid as a catalyst, heating and refluxing for 15h at 60 ℃, washing the filtered solid with analytically pure methanol until the filtrate is colorless after the reaction is finished, and obtaining brick red solid, namely covalent metal organic polymer;

and 4, step 4: preparation of alloy-loaded covalent organic polymers

Under the protection of nitrogen, carrying out pyrolysis treatment on the prepared covalent metal organic polymer at the temperature of 800-1000 ℃ and the heating rate of 2-5 ℃/min for 4h, and preparing the iron-tin alloy loaded sulfur-nitrogen co-doped carbon electrocatalyst.

2. An iron-tin alloy supported sulfur-nitrogen co-doped carbon electrocatalyst prepared by the method of claim 1.

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