CN109659570B - Application of metal organic framework compound hollow microspheres loaded with iron cobalt sulfide - Google Patents

Abstract

The invention discloses an application of a metal organic framework compound hollow microsphere loaded with iron-cobalt sulfide, wherein the metal organic framework compound hollow microsphere is used for burningThe fuel cell ORR catalyst is used to catalyze the oxygen reduction reaction at the cathode. The metal organic framework compound is obtained by adopting a preparation method which comprises the following steps: (1) providing polystyrene nano-microspheres; (2) loading MOF derivatives which take Fe and Co as metal ion centers, namely precursors, on the polystyrene nano microspheres; (3) calcining the precursor, carbonizing at high temperature, and removing the polystyrene nano microspheres; (4) and carrying out sulfur doping on the carbonized product. The metal organic framework compound hollow microsphere has excellent electrocatalytic activity and can be used as an ORR electrocatalyst of a fuel cell. The optimal limit diffusion current density is 4.1mA/cm^‑2The theoretical limit diffusion current density of the platinum and the carbon which are close to the noble metal catalyst is 6mA/cm^‑2But at a lower cost.

Description

Application of metal organic framework compound hollow microspheres loaded with iron cobalt sulfide

Technical Field

The invention belongs to the technical field of application of metal organic framework compound (MOF) derivatives, and particularly relates to application of iron-cobalt sulfide supported metal organic framework compound hollow microspheres, which can be applied to an ORR catalyst of a fuel cell.

Background

The fuel cell is a novel environment-friendly and efficient energy source and consists of two half reactions, namely fuel oxidation at an anode and oxygen reduction at a cathode. The oxidation reaction rate is much higher than the reduction reaction rate, so it is important to increase the oxygen reduction reaction rate of the cathode. The cathode reaction kinetics process is very slow, and the current commercial Pt catalyst is expensive, which becomes one of the bottlenecks in large-scale use of fuel cells. Studies have shown that the Pt catalyst used in the cathode of the fuel cell accounts for about 40% of the cost of the cell. Therefore, a fuel cell cathode oxygen reduction catalyst which is cheap, low in pollution, capable of replacing Pt in catalytic performance and easy to produce in large scale is important.

In summary, the key to obtaining an ORR catalyst with excellent performance is to design and synthesize a porous carbon material with high dispersion of active sites and large specific surface area.

Disclosure of Invention

The invention aims to provide application of a metal organic framework compound hollow microsphere.

The preparation process of the iron-cobalt sulfide supported metal organic framework compound hollow microsphere is simple, low in cost and environment-friendly, and the iron-cobalt sulfide supported metal organic framework compound hollow microsphere is used for catalyzing the oxygen reduction reaction of a cathode by using the iron-cobalt sulfide supported metal organic framework compound hollow microsphere as a fuel cell ORR catalyst and has an excellent catalytic effect.

The metal organic framework compound is obtained by adopting a preparation method which comprises the following steps:

(1) providing polystyrene nano-microspheres;

(2) loading MOF derivatives which take Fe and Co as metal ion centers, namely precursors, on the polystyrene nano microspheres;

(3) calcining the precursor, carbonizing at high temperature, and removing the polystyrene nano microspheres;

(4) and carrying out sulfur doping on the carbonized product.

Further, the metal organic framework compound hollow microsphere loaded with iron cobalt sulfide is used for a fuel cell ORR catalyst, and a specific embodiment is as follows:

the metal organic framework compound hollow microspheres loaded with the iron-cobalt sulfide are prepared into catalyst slurry, and the catalyst slurry is prepared on a fuel cell cathode material.

Specifically, the catalyst slurry is prepared by mixing a metal organic framework compound, a binder, a dispersant and a pore-forming agent.

When the catalyst slurry is prepared, the adhesive can be nafion, PVB, PTFE and PVDF, and the using amount of the adhesive is 5-15% of the mass of the metal organic framework compound; the dispersant can adopt deionized water and liquid alcohol such as ethanol, glycol, isopropanol and the like with a certain proportion, and the using amount of the dispersant is 10-50% of the mass of the metal organic framework compound; the pore former is acted upon by the alcohol in the dispersant.

Specifically, the catalyst slurry can be coated, hot pressed, or rolled onto the fuel cell cathode material.

Further, the polystyrene nano-microsphere is synthesized by adopting the following method:

(1a) preparing an aqueous solution of an emulsifier, placing the aqueous solution of the emulsifier in a reaction container, and placing the aqueous solution of the emulsifier in an inert atmosphere to remove a polymerization inhibitor in the emulsifier;

(1b) heating to reflux temperature, then dripping an initiator into the reaction container in a reflux state, and reacting;

(1c) adding a styrene monomer and a co-emulsifier into a reaction vessel;

(1d) raising the temperature to the reflux temperature again, then reacting in a reflux state, and cooling to room temperature after the reaction is finished;

(1e) adding an aqueous solution of inorganic salt into a reaction container for demulsification to obtain a suspension;

(1f) carrying out reduced pressure suction filtration or centrifugal machine centrifugation on the suspension, and then sequentially carrying out washing, reduced pressure suction filtration and drying to obtain the polystyrene nano-microspheres;

the whole synthesis process of the polystyrene nano-microsphere is carried out in an inert atmosphere.

The emulsifier adopts sodium dodecyl sulfate, the initiator adopts potassium persulfate or ammonium persulfate, the co-emulsifier adopts n-butyl alcohol, and the aqueous solution of the inorganic salt adopts the aqueous solution of potassium chloride.

Further, the molar ratio of Fe to Co in the MOF structure is 1: (1-3).

Further, the MOF derivatives taking Fe and Co as metal ion centers are loaded on the polystyrene nanospheres, and specifically:

(2a) dispersing the polystyrene nano-microspheres in a first dispersing agent to obtain a dispersion liquid A;

(2b) dispersing an iron source and a cobalt source in a second dispersing agent to obtain a dispersion liquid B; the second dispersant is the same as the first dispersant;

(2c) dissolving 2-methylimidazole in ethanol to obtain a solution C;

(2d) dropping the dispersion liquid B into the dispersion liquid A and stirring, then adding the solution C, and stirring for reaction;

(2e) carrying out reduced pressure rotary evaporation, cooling to room temperature, recrystallization, reduced pressure suction filtration and drying on the reactant solution in sequence to obtain a product;

the iron source FeCl₃Or Fe (NO)₃)₃·6H₂O; the cobalt source is CoCl₂·6H₂O or Co (NO)₃)₂·6H₂O。

Further, sulfur doping is carried out on the carbonized product, and specifically the method comprises the following steps:

grinding and mixing the carbonized product and a sulfur source, and then calcining in an inert atmosphere; the sulfur source is thiourea.

The invention has the following advantages and beneficial effects:

the metal organic framework compound hollow microsphere loaded with the iron-cobalt sulfide is used as an ORR catalyst of a fuel cell, and the metal organic framework compound hollow microsphere loaded with the iron-cobalt sulfide takes Fe and Co as metal ion centers and MOF derivatives wrapped on polystyrene nano microspheres as precursors, and then modifies the MOF structure through sulfur atom doping. The metal organic framework compound hollow microsphere has a porous structure, large specific surface area and many reactive attachment points, so that the metal organic framework compound hollow microsphere has excellent electron and reduction product transmission performance.

Tests prove that the metal organic framework compound hollow microsphere loaded with the iron-cobalt sulfide has excellent electrocatalytic activity and can be used as an ORR electrocatalyst of a fuel cell. The optimal limit diffusion current density of the metal organic framework compound hollow microsphere loaded with the iron cobalt sulfide is 4.1mA/cm^-2The theoretical limit diffusion current density of the platinum and the carbon which are close to the noble metal catalyst is 6mA/cm^-2But at a lower cost.

Drawings

FIG. 1 is an XRD representation of 1-1-ZIF @ PS-C-S;

FIG. 2 is an XRD characterization of 1-2-ZIF @ PS-C-S;

FIG. 3 is an XRD characterization of 1-3-ZIF @ PS-C-S;

FIG. 4 is a CV cyclic voltammogram at nitrogen saturation versus oxygen saturation for 1-1-ZIF @ PS-C-S;

FIG. 5 is a CV cyclic voltammogram at nitrogen saturation versus oxygen saturation for 1-2-ZIF @ PS-C-S;

FIG. 6 is a CV cyclic voltammogram at nitrogen saturation versus oxygen saturation for 1-3-ZIF @ PS-C-S.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that "polystyrene nanospheres" will be hereinafter referred to as "PS microspheres", emulsifier "sodium dodecyl sulfate" will be referred to as "SDS", and initiator "potassium persulfate" will be referred to as "KPS".

Example 1

The PS microspheres can be purchased directly or prepared by themselves, and this embodiment provides a preparation method of the PS microspheres, but the preparation method of the PS microspheres is not limited thereto.

The steps of the PS microspheres in this example are as follows:

(1) 0.3g of SDS was dissolved in 180ml of deionized water to obtain an SDS solution, the SDS solution was placed in a three-necked flask, and nitrogen was passed through the SDS solution to remove the polymerization inhibitor in the SDS.

(2) Heating the SDS solution in the three-mouth bottle to 80 ℃, quickly dripping the KPS aqueous solution into the three-mouth bottle in a reflux state, and reacting for 15min after dripping. The dropwise added KPS aqueous solution was obtained by adding 0.3g of KPS to 15ml of deionized water.

(3) Slowly dripping the mixed solution of styrene monomer and n-butanol into the three-mouth bottle, and reacting for 30min after dripping. The mixture was obtained by mixing 0.3g of styrene monomer and 0.2g of n-butanol.

(4) 9.7g of styrene monomer was added in one portion to the three-necked flask and reacted for 2 hours under reflux.

(5) Naturally cooling to room temperature.

(6) At room temperature, adding a potassium chloride solution into the three-mouth bottle by a small amount of times until obvious precipitation occurs, and stopping adding the potassium chloride solution; the potassium chloride solution was added while maintaining the stirring of the liquid in the three-necked flask.

(7) Standing for 24h for demulsification.

(8) And (3) carrying out reduced pressure suction filtration or centrifugal machine centrifugation on the suspension obtained after demulsification, and then washing, reduced pressure suction filtration and drying the obtained white solid in sequence to obtain a white powder product, namely PS microspheres.

(9) Vacuum filtering the demulsified mixed solution orCentrifuging by a centrifuge, washing the obtained white solid twice by distilled water and ethanol in sequence, carrying out vacuum filtration and drying; obtaining white powder PS microspheres with the structural formula

It should be noted that the entire process of synthesizing the PS microspheres is performed under the protection of inert atmosphere.

Examples 2-4 will provide synthesis examples of three precursors, in which the molar ratios of Fe and Co are, in order, 1: 1. 1: 2. 1:3, respectively named as 1-1-ZIF @ PS, 1-2-ZIF @ PS and 1-3-ZIF @ PS.

The PS microspheres used in examples 2-4 were the products of example 1.

Example 2

This example will provide an example of the synthesis of the MOF derivative 1-1-ZIF @ PS, with the following steps:

(1) in a three-necked flask, 0.27g of PS microspheres was dispersed in 5ml of deionized water and 20ml of ethanol, the temperature was controlled at 30 ℃, and the mixture was mechanically stirred until uniform dispersion was achieved, and the resulting dispersion was designated as dispersion A.

(2) 0.78g of FeCl₃And 1.142g of CoCl₂·6H₂O was uniformly dispersed in 15ml of ethanol, and the resulting dispersion was designated as dispersion B.

(3) 2.362g of 2-methylimidazole were dissolved in 25ml of ethanol, and the resulting solution was designated as solution C.

(4) Slowly adding the dispersion liquid B into the dispersion liquid A, quickly turning the mixed liquid into brown blue in a three-mouth bottle, and vigorously stirring the mixed liquid for 30 min.

(5) And adding the solution C into a three-necked bottle at one time, wherein the mixed solution in the three-necked bottle quickly becomes brownish black, and stirring for reacting overnight.

(6) And (3) carrying out reduced pressure rotary evaporation on the reactant in the three-necked bottle, naturally cooling, and then sequentially carrying out ethanol recrystallization, reduced pressure suction filtration and filter cake drying to obtain the bluish purple product 1-1-ZIF @ PS.

Example 3

This example will provide an example of the synthesis of the MOF derivative 1-2-ZIF @ PS, with the following steps:

(1) in a three-necked flask, 1.08g of PS microspheres were dispersed in 10ml of deionized water and 50ml of ethanol, the temperature was controlled at 30 ℃, and the mixture was mechanically stirred until uniform dispersion was achieved, and the resulting dispersion was designated as dispersion A.

(2) 1.04g of FeCl₃And 3.05g of CoCl₂·6H₂O was uniformly dispersed in 45ml of ethanol, and the resulting dispersion was designated as dispersion B.

(3) 9.448g of 2-methylimidazole were dissolved in 80ml of ethanol, and the resulting solution was designated as solution C.

(4) Slowly adding the dispersion liquid B into the dispersion liquid A, quickly turning the mixed liquid into brown blue in a three-mouth bottle, and vigorously stirring the mixed liquid for 30 min.

(5) And adding the solution C into a three-necked bottle at one time, wherein the mixed solution in the three-necked bottle quickly becomes brownish black, and stirring for reacting overnight.

(6) And (3) carrying out reduced pressure rotary evaporation on the reactant in the three-necked bottle, naturally cooling, and then sequentially carrying out ethanol recrystallization, reduced pressure suction filtration and filter cake drying to obtain the bluish purple product 1-1-ZIF @ PS.

Example 4

This example will provide an example of the synthesis of the MOF derivative 1-3-ZIF @ PS, with the following steps:

(1) in a three-necked flask, 0.54g of PS microspheres was dispersed in 10ml of deionized water and 40ml of ethanol, the temperature was controlled at 30 ℃, and the mixture was mechanically stirred until uniform dispersion was achieved, and the resulting dispersion was designated as dispersion A.

(2) 0.78g of FeCl₃And 3.426g of CoCl₂·6H₂O was uniformly dispersed in 30ml of ethanol, and the resulting dispersion was designated as dispersion B.

(3) 4.724g of 2-methylimidazole were dissolved in 80ml of ethanol, and the resulting solution was designated as solution C.

(4) Slowly adding the dispersion liquid B into the dispersion liquid A, quickly turning the mixed liquid into brown blue in a three-mouth bottle, and vigorously stirring the mixed liquid for 30 min.

(5) And adding the solution C into a three-necked bottle at one time, wherein the mixed solution in the three-necked bottle quickly becomes brownish black, and stirring for reacting overnight.

(6) And (3) carrying out reduced pressure rotary evaporation on the reactant in the three-necked bottle, naturally cooling, and then sequentially carrying out ethanol recrystallization, reduced pressure suction filtration and filter cake drying to obtain the bluish purple product 1-3-ZIF @ PS.

Example 5

This example will provide an example of high temperature carbonization of precursors 1-1-ZIF @ PS, 1-2-ZIF @ PS, and 1-3-ZIF @ PS.

Respectively placing the precursors 1-1-ZIF @ PS, 1-2-ZIF @ PS and 1-3-ZIF @ PS in different porcelain boats, placing the porcelain boats in a tube furnace, and carrying out high-temperature calcination in an air atmosphere. The calcination process parameters are as follows: the temperature in the tube furnace is raised to 500 ℃ at the temperature raising rate of 2.5 ℃/min, and the temperature is kept for 3 h. After the calcination, the calcined product was naturally cooled to room temperature and ground for 2 hours by using a mortar. The obtained products are respectively named as 1-1-ZIF @ PS-C, 1-2-ZIF @ PS-C and 1-3-ZIF @ PS-C.

Example 6

This example will provide sulfur doped examples of the carbonized products 1-1-ZIF @ PS-C, 1-2-ZIF @ PS-C, 1-3-ZIF @ PS-C.

Mixing 1-1-ZIF @ PS-C, 1-2-ZIF @ PS-C and 1-3-ZIF @ PS-C with thiourea according to the mass ratio of 1:2, fully grinding for 4h by using a mortar, and then respectively placing in different porcelain boats. And (4) putting the porcelain boat into a tube furnace, and carrying out high-temperature calcination in a nitrogen atmosphere. The calcination process parameters are as follows: the temperature in the tube furnace is raised to 600 ℃ at the temperature raising rate of 2.5 ℃/min, and the temperature is kept for 3 h. After the calcination, the calcined product was naturally cooled to room temperature and ground for 2 hours by using a mortar. The obtained products are respectively named as 1-1-ZIF @ PS-C-S, 1-2-ZIF @ PS-C-S and 1-3-ZIF @ PS-C-S.

FIG. 1 is an XRD characterization of 1-1-ZIF @ PS-C-S, and by comparison with a standard JPC-DS card (JCPDS99-0109), it can be seen that FIG. 1 is Fe-Co sulfide_0.8Co_0.2The S phase is Fe-Co sulfide at the 2 theta angles of 29.97 degrees, 33.90 degrees and 43.78 degrees_0.8Co_0.2The characteristic peaks of S correspond to the crystal faces of (200), (201) and (202), respectively, and the peaks are sharp and regular, have narrow half-peak width and are good in crystallinity. No hetero-peaks, indicated as pure phase Fe-Co-sulfide_0.8Co_0.2And S. The characteristic peak of elemental sulfur is not shown, which indicates that the sulfur is completely doped into the crystal lattice and no residual elemental sulfur exists on the surface. Nor does itThere is a broad dispersion peak of amorphous carbon, indicating that the PS microspheres have been eliminated during the high temperature carbonization process in air atmosphere.

FIGS. 2 and 3 are XRD characterization diagrams of 1-2-ZIF @ PS-C-S and 1-3-ZIF @ PS-C-S, respectively, and by comparison with a standard JPC-DS card (JCPDS99-0109), the 2 theta angles of 29.97 degrees, 33.90 degrees and 43.78 degrees respectively correspond to Fe and Co sulfide Fe_0.8Co_0.2The (200), (201), and (202) crystal planes of S. However, as compared with FIG. 1, it is evident that as the Co content in the composite increases, the intensity of the characteristic peak decreases and the half-value width increases, indicating that the degree of lattice distortion increases and the degree of crystallinity decreases, i.e., the degree of crystallinity is 1-3-ZIF @ PS-C-S<1-2-ZIF@PS-C-S<1-1-ZIF @ PS-C-S. In addition, the 2 θ angles of 45.8 ° and 53.3 ° correspond to diffraction peaks of (111) and (200) crystal planes of the metallic cobalt nanoparticles, which shows that the cobalt nanoparticles appear in the composite as the content of Co increases compared with fig. 1.

Example 7

The embodiment is an electrocatalytic performance test of 1-1-ZIF @ PS-C-S, 1-2-ZIF @ PS-C-S and 1-3-ZIF @ PS-C-S, and the electrocatalytic performance test shows that the metal organic framework compound hollow microspheres loaded with iron-cobalt sulfide have good electrocatalytic activity on oxygen reduction and can be used as catalysts for cathode oxygen reduction reaction of fuel cells.

The electrocatalytic performance test procedure was as follows:

(1) and preparing a working electrode, namely modifying the glassy carbon electrode by respectively adopting 1-1-ZIF @ PS-C-S, 1-2-ZIF @ PS-C-S and 1-3-ZIF @ PS-C-S.

The modification of the glassy carbon electrode specifically comprises the following steps:

(1a) cleaning and polishing the glassy carbon electrode;

(1b) 5mg of the product of example 6 was weighed into a 2ml centrifuge tube. Adding 80 mu L of deionized water, 900 mu L of isopropanol and 20 mu L of nafion into a centrifuge tube by using a liquid transfer gun, and performing ultrasonic treatment for 40min to obtain ink;

(1c) and (3) adopting a dripping method, dripping 6 mu L of ink on the surface of the glassy carbon electrode by using a liquid transfer gun for three times, and naturally drying.

(2) The electrocatalytic performance tests of the present example all employ a three-electrode system,morning 660E, Pine rotating disk electrode of USA, the diameter of which is 5mm, and the area is 0.19625cm²The reference electrode is a saturated mercury/mercury oxide electrode, the counter electrode is a platinum electrode, the electrolyte is 0.1M KOH solution, and deionized water is adopted for preparation.

The electrochemical performance test was performed using Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). CV experimental conditions were: 0.1M KOH solution prepared with deionized water, N was first introduced₂Saturation is reached at 0.5 V.S. in 40min^-1Scanning at a scanning speed for 100 circles to activate the electrodes; then replaced by O₂Saturation is reached at 40min, with 50mV S^-1The sweep rate yields a CV diagram. The LSV experimental conditions were: o is₂Saturated 0.1M KOH solution, sweep 5 mV. S^-1The rotation speed was varied from high to low, and 2000rpm, 1600rpm, 1200rpm, 800rpm, and 400rpm were sequentially performed.

CV cyclic voltammetry results are shown in figures 4-6, figure 4 is a CV cyclic voltammetry graph when 1-1-ZIF @ PS-C-S is used as a catalyst and an electrode is subjected to electrocatalytic oxygen reduction, and it can be seen from the figure that no redox peak appears in a nitrogen saturated electrolyte, and in contrast, an obvious redox peak appears at a position of-0.3V in an oxygen saturated electrolyte, which confirms that the 1-1-ZIF @ PS-C-S has better electrocatalytic activity on oxygen reduction. FIG. 5 is a CV cyclic voltammogram of 1-2-ZIF @ PS-C-S as a catalyst in an electrocatalytic oxygen reduction electrode, and compared with CV diagrams of a nitrogen saturated electrolyte and an oxygen saturated electrolyte, it is obvious that 1-2-ZIF @ PS-C-S also has electrocatalytic activity, and the potential corresponding to the peak value is-0.28V. FIG. 6 is a CV cyclic voltammogram of 1-3-ZIF @ PS-C-S as a catalyst when an electrode is electro-catalytically reduced with oxygen, and the CV diagram in an oxygen-saturated electrolyte is also evident with an oxidation-reduction peak and a peak potential of-0.24V.

The oxygen reduction of the catalyst catalytic cathode is a process of converting chemical energy into electric energy, and the larger the reduction potential corresponding to a reduction peak is, the better the catalytic activity of the electrocatalyst is. Thus, the electrocatalytic activity sequences of 1-1-ZIF @ PS-C-S, 1-2-ZIF @ PS-C-S, and 1-3-ZIF @ PS-C-S are: 1-3-ZIF @ PS-C-S >1-2-ZIF @ PS-C-S >1-1-ZIF @ PS-C-S. Comparing the analysis result of XRD chart, the metal organic framework compound hollow microsphere has good ORR activity, and the catalytic activity can be effectively improved by increasing the content of Co metal nano particles.

The LSV cyclic voltammetry results are shown in Table 1, and the limiting diffusion current density (unit: mA/cm) of the glassy carbon electrode modified by the catalyst under different rotating speeds^-2). The LSV polarization curve data reflects the kinetics of the cathodic oxygen reduction reaction. In the limit diffusion platform area, the higher the limit diffusion current density is, the more sufficient the oxygen reduction power is. As can be seen from table 1, the limiting diffusion current density increases with increasing rotation speed for the same catalyst, which also corroborates the CV cyclic voltammetry results with respect to the better ORR activity of all three catalysts. When the rotating speed of the rotating disc electrode is 1600rpm, the theoretical limit diffusion current density of the commercial noble metal catalyst platinum carbon is 6mA/cm^-2. Compared with the limiting diffusion current density of the catalyst under 1600rpm, the limiting diffusion current density of 1-1-ZIF @ PS-C-S is 3.2mA/cm^-2The limiting diffusion current density of the 1-2-ZIF @ PS-C-S is 3.6mA/cm^-2The limiting diffusion current density of the 1-3-ZIF @ PS-C-S is 4.1mA/cm^-2. It can be seen that the electrocatalytic activity sequences of 1-1-ZIF @ PS-C-S, 1-2-ZIF @ PS-C-S, and 1-3-ZIF @ PS-C-S are as follows: 1-3-ZIF @ PS-C-S>1-2-ZIF@PS-C-S>1-1-ZIF @ PS-C-S. This also validates the analytical results of CV cyclic voltammetry results: the metal organic framework compound hollow microsphere loaded with the iron-cobalt sulfide has good ORR activity, and the catalytic activity of the metal organic framework compound hollow microsphere can be effectively improved by increasing the content of Co.

TABLE 1 limiting diffusion current density of glassy carbon electrode after catalyst modification

	400rpm	800rpm	1200rpm	1600rpm	2000rpm
						1-1-ZIF@PS-C-S	2.6mA/cm-2	2.8mA/cm-2	3.1mA/cm-2	3.2mA/cm-2	3.5mA/cm-2
1-2-ZIF@PS-C-S	2.4mA/cm-2	2.9mA/cm-2	3.4mA/cm-2	3.6mA/cm-2	3.9mA/cm-2
						1-3-ZIF@PS-C-S	3mA/cm-2	3.3mA/cm-2	3.8mA/cm-2	4.1mA/cm-2	4.3mA/cm-2

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (4)

1. The application of the metal organic framework compound hollow microsphere loaded with iron-cobalt sulfide is characterized in that:

the metal organic framework compound hollow microsphere is used for a fuel cell ORR catalyst and is used for catalyzing the oxygen reduction reaction of a cathode;

the metal organic framework compound is obtained by adopting a preparation method which comprises the following steps:

(1) providing polystyrene nano-microspheres;

(2) loading MOF derivatives which take Fe and Co as metal ion centers, namely precursors, on the polystyrene nano microspheres; the molar ratio of Fe to Co in the MOF structure is 1: (1-3);

(3) calcining the precursor, carbonizing at high temperature, and removing the polystyrene nano microspheres; the high-temperature carbonization process parameters are as follows: heating the temperature in the tube furnace to 500 ℃ at the heating rate of 2.5 ℃/min, and preserving the heat for 3 h;

(4) sulfur doping the carbonized product;

the method is characterized in that MOF derivatives taking Fe and Co as metal ion centers are loaded on polystyrene nano microspheres, and the specific steps are as follows:

(2a) dispersing the polystyrene nano-microspheres in a first dispersing agent to obtain a dispersion liquid A;

(2b) dispersing an iron source and a cobalt source in a second dispersing agent to obtain a dispersion liquid B; the second dispersant is the same as the first dispersant;

(2c) dissolving 2-methylimidazole in ethanol to obtain a solution C;

(2d) dropping the dispersion liquid B into the dispersion liquid A and stirring, then adding the solution C, and stirring for reaction;

(2e) carrying out reduced pressure rotary evaporation, cooling to room temperature, recrystallization, reduced pressure suction filtration and drying on the reactant solution in sequence to obtain a product;

the iron source is FeCl₃Or Fe (NO)₃)₃·6H₂O; the cobalt source is CoCl₂·6H₂O or Co (NO)₃)₂·6H₂O；

And (3) carrying out sulfur doping on the carbonized product, specifically:

grinding and mixing the carbonized product and a sulfur source, and then calcining in an inert atmosphere; the sulfur source is thiourea;

the metal organic framework compound hollow microsphere is used for a fuel cell ORR catalyst, and specifically comprises the following components:

preparing a metal organic framework compound into catalyst slurry, and preparing the catalyst slurry on a cathode material of a fuel cell;

preparing a metal organic framework compound into catalyst slurry, which specifically comprises the following steps:

the metal organic framework compound, the binder, the dispersant and the pore-forming agent are mixed to prepare the catalyst slurry.

2. The use of the fe-co sulfide supported metal-organic framework compound hollow microspheres as claimed in claim 1, wherein:

and (3) preparing the catalyst slurry on the cathode material of the fuel cell by adopting a coating, hot pressing or rolling mode.

3. The use of the fe-co sulfide supported metal-organic framework compound hollow microspheres as claimed in claim 1, wherein:

the polystyrene nano-microsphere is synthesized by adopting the following method:

(1a) preparing an aqueous solution of an emulsifier, placing the aqueous solution of the emulsifier in a reaction container, and placing the aqueous solution of the emulsifier in an inert atmosphere to remove a polymerization inhibitor in the emulsifier;

(1b) heating to reflux temperature, then dripping an initiator into the reaction container in a reflux state, and reacting;

(1c) adding a styrene monomer and a co-emulsifier into a reaction vessel;

(1d) raising the temperature to the reflux temperature again, then reacting in a reflux state, and cooling to room temperature after the reaction is finished;

(1e) adding an aqueous solution of inorganic salt into a reaction container for demulsification to obtain a suspension;

(1f) carrying out reduced pressure suction filtration or centrifugal machine centrifugation on the suspension, and then sequentially carrying out washing, reduced pressure suction filtration and drying to obtain the polystyrene nano-microspheres;

the whole synthesis process of the polystyrene nano-microsphere is carried out in an inert atmosphere.

4. The use of the fe-co sulfide supported metal-organic framework compound hollow microspheres as claimed in claim 3, wherein:

the emulsifier adopts sodium dodecyl sulfate, the initiator adopts potassium persulfate or ammonium persulfate, the co-emulsifier adopts n-butyl alcohol, and the aqueous solution of the inorganic salt adopts the aqueous solution of potassium chloride.

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