Method for preparing a composite material, composite material and electrocatalyst

Abstract

The application relates to the technical field of electrocatalytic materials, and particularly discloses a preparation method of a composite material, the composite material and an electrocatalyst. The preparation method of the composite material comprises the following steps: mixing an iron source, a nitrogen source, a phosphorus source, a sulfur source and a catalyst in a solvent to obtain a mixed solution; after the iron source, the nitrogen source, the phosphorus source and the sulfur source in the mixed solution fully react, the product after the reaction is washed and dried to obtain a precursor; and the precursor is subjected to carbonization treatment to obtain the composite material, wherein the composite material comprises C, P, S, N and Fe x P. The composite material obtained through the preparation method solves the problems of high price and poor stability of an existing ORR electrocatalyst.

Description

Technical Field

[0001] This application relates to the field of electrocatalytic materials technology, and in particular to a method for preparing a composite material, the composite material, and an electrocatalyst. Background Technology

[0002] An air battery is a novel chemical battery that uses air as the positive electrode and a metal as the negative electrode. During discharge, the air electrode undergoes an oxygen reduction reaction (ORR), and during charging, an oxygen evolution reaction (OER) occurs. The extremely slow reaction kinetics of ORR significantly hinder the large-scale commercial application of air batteries. Therefore, an ORR electrocatalyst is needed to improve the ORR rate. Currently, the most widely used ORR electrocatalyst is the noble metal platinum-based catalyst. However, platinum is expensive and scarce, increasing the application cost of air batteries. Furthermore, platinum-based catalysts exhibit poor stability and methanol resistance. Therefore, developing a low-cost, highly active, and stable ORR electrocatalyst is of great significance. Summary of the Invention

[0003] This application provides a method for preparing a composite material, the composite material, and an electrocatalyst, aiming to solve the problems of high cost and poor stability of existing ORR electrocatalysts.

[0004] In a first aspect, embodiments of this application provide a method for preparing a composite material, the method comprising:

[0005] Iron source, nitrogen source, phosphorus source, sulfur source and catalyst are mixed and dissolved in solvent to obtain a mixed solution;

[0006] After the iron source, nitrogen source, phosphorus source and sulfur source in the mixture have fully reacted, the product after reaction is washed and dried to obtain the precursor.

[0007] The precursor is subjected to carbonization treatment to obtain a composite material, wherein the composite material includes C, P, S, N and FexP.

[0008] In one possible embodiment, the iron source comprises at least one of ferrous sulfate heptahydrate, ferrous chloride, and ferrous nitrate; and / or, the nitrogen source comprises 1,10-phenanthroline; and / or, the phosphorus source comprises hexachlorotriphosphazene; and / or, the sulfur source comprises 4,4-dihydroxydiphenyl sulfone; and / or, the catalyst comprises triethylamine; and / or, the solvent comprises methanol.

[0009] In one possible implementation, the molar ratio of iron in the iron source to nitrogen in the nitrogen source is 1:6; and / or, the molar ratio of phosphorus in the phosphorus source to sulfur in the sulfur source is 1:1.

[0010] In one possible implementation, the washing includes the step of sequentially washing the product after the reaction with the solvent and ultrapure water; and / or, the drying temperature is 40°C to 60°C.

[0011] In one possible implementation, the carbonization process includes heating the precursor to 900°C to 1100°C in a non-reactive atmosphere at a heating rate of 2°C / min to 10°C / min, and holding the temperature at that temperature for 2.0 h to 4.0 h.

[0012] In one possible implementation, the composite material comprises graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and thiophene sulfur.

[0013] Secondly, embodiments of this application provide a composite material, which is prepared using the composite material preparation method described in any of the preceding claims, and the composite material includes C, P, S, N, and Fe. x P.

[0014] In one possible implementation, the specific surface area of ​​the composite material is 603 m². 2 / g~818m 2 / g; and / or, the composite material has a hierarchical porous structure.

[0015] In one possible implementation, the composite material has methanol resistance; and / or, the composite material comprises graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and thiophene sulfide.

[0016] Thirdly, embodiments of this application provide an electrocatalyst, the electrocatalyst comprising the composite material described in any of the preceding claims.

[0017] This application discloses a method for preparing a composite material, the composite material itself, and an electrocatalyst. The method for preparing the composite material involves first mixing an iron source, a nitrogen source, a phosphorus source, a sulfur source, and a catalyst in a solvent to obtain a mixed solution. Then, after the iron source, nitrogen source, phosphorus source, and sulfur source in the mixed solution have fully reacted, the reaction product is washed and dried to obtain a precursor. Finally, the precursor is carbonized to obtain the composite material. The composite material comprises C, P, S, N, and Fe. x P, the composite material prepared by the method disclosed in the embodiments of this application can be used as an ORR electrocatalyst, which solves the problems of high price and poor stability of existing ORR electrocatalysts. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic flowchart illustrating the method for preparing the composite material provided in the embodiments of this application;

[0020] Figure 2 EDS spectra of the composite materials provided in the embodiments of this application;

[0021] Figure 3(a) shows the full-spectrum XPS spectrum of the composite material provided in the embodiment of this application;

[0022] Figure 3(b) shows the C1s XPS spectrum of the composite material provided in the embodiment of this application;

[0023] Figure 3(c) shows the N1s XPS spectrum of the composite material provided in the embodiment of this application;

[0024] Figure 3(d) shows the Fe 2p XPS spectrum of the composite material provided in the embodiments of this application;

[0025] Figure 3(e) shows the P 2p XPS spectrum of the composite material provided in the embodiments of this application;

[0026] Figure 3(f) shows the S 2p XPS spectrum of the composite material provided in the embodiment of this application;

[0027] Figure 4(a) is a SEM characterization image of the composite material provided in the embodiment of this application;

[0028] Figure 4(b) is a SEM characterization image of another composite material provided in the embodiments of this application;

[0029] Figure 4(c) is a SEM characterization image of another composite material provided in the embodiment of this application;

[0030] Figure 5 Nitrogen adsorption-desorption isotherms of the composite material provided in the embodiments of this application;

[0031] Figure 6 A pore size distribution diagram of the composite material provided in the embodiments of this application;

[0032] Figure 7 CV curve of the composite material provided in the embodiments of this application;

[0033] Figure 8 LSV curves provided for embodiments of this application;

[0034] Figure 9 Cyclic stability curves of the platinum-carbon catalyst and composite material provided in the embodiments of this application;

[0035] Figure 10 The graph shows the methanol resistance performance of the platinum-carbon catalyst and composite material provided in the embodiments of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0038] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0039] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0040] Please see Figure 1 , Figure 1 This is a schematic flowchart of a method for preparing a composite material according to an embodiment of this application. The method for preparing the composite material includes steps S100 to S300.

[0041] Step S100: Mix the iron source, nitrogen source, phosphorus source, sulfur source and catalyst in a solvent to obtain a mixed solution.

[0042] The iron source is used to provide iron, and the iron source includes at least one of ferrous sulfate heptahydrate, ferrous chloride, and ferrous nitrate; the nitrogen source is used to provide nitrogen, and the nitrogen source includes 1,10-phenanthroline; the phosphorus source is used to provide phosphorus, and the phosphorus source includes hexachlorotriphosphazene; the sulfur source is used to provide sulfur, and the sulfur source includes 4,4-dihydroxydiphenyl sulfone; the catalyst is used to catalyze the reaction between the substances in the mixture, and the catalyst includes triethylamine; the solvent includes methanol.

[0043] In some embodiments, the molar ratio of iron in the iron source to nitrogen in the nitrogen source is 1:6. This embodiment can give the obtained composite material more three-dimensional pore channels. These three-dimensional pore channels allow oxygen molecules to fully enter the catalyst to carry out the oxygen reduction reaction. The large number of pores is conducive to the attachment of active sites, increasing the contact area between the catalyst and the electrolyte and oxygen to improve catalytic activity.

[0044] In some embodiments, the molar ratio of phosphorus in the phosphorus source to sulfur in the sulfur source is 1:1. This embodiment can give the obtained composite material more three-dimensional pore channels. These three-dimensional pore channels allow oxygen molecules to fully enter the interior of the catalyst for oxygen reduction reaction. The large number of pores is beneficial for the attachment of active sites, increasing the contact area between the catalyst and the electrolyte and oxygen to improve catalytic activity.

[0045] For example, 0.278g of ferrous sulfate heptahydrate, 0.54g of 1,10-phenanthroline, 0.35g of hexachlorotriphosphazene and 0.75g of 4,4-dihydroxydiphenyl sulfone were mixed and dissolved in 100ml of methanol.

[0046] Understandably, this application does not limit the amount of methanol, as long as the iron source, nitrogen source, phosphorus source and sulfur source can be fully mixed.

[0047] In some embodiments, step S100 includes steps S101 to S103 to obtain the composite material with more three-dimensional pore channels. These three-dimensional pore channels allow oxygen molecules to fully enter the catalyst interior for oxygen reduction reaction, while the numerous pore structures facilitate the attachment of active sites, increasing the contact area between the catalyst and the electrolyte and oxygen to improve catalytic activity.

[0048] Step S101: Dissolve the iron source and the nitrogen source in the solvent.

[0049] Step S102: After the iron source and the nitrogen source are mixed evenly in the solvent, the phosphorus source and the sulfur source are added.

[0050] Step S103: After the phosphorus source and the sulfur source are mixed evenly in the solvent, the catalyst is added to obtain the mixture.

[0051] Step S200: After the iron source, nitrogen source, phosphorus source and sulfur source in the mixture have fully reacted, the product after reaction is washed and dried to obtain the precursor.

[0052] To accelerate the reaction rate of the iron, nitrogen, phosphorus, and sulfur sources in the mixture, a magnetic stirrer is used to stir the mixture in some embodiments. Preferably, the mixture is stirred with a magnetic stirrer at a speed of 600–800 rpm for 18–24 hours.

[0053] In some embodiments, the washing includes sequentially washing the reaction product with the solvent and then with ultrapure water to remove impurities from the reaction product. Preferably, the reaction product is centrifuged and washed sequentially with the solvent and then with ultrapure water at a speed of 11,500 rpm.

[0054] In some embodiments, the drying temperature is 40°C to 60°C. When the drying temperature is below 40°C, the drying rate is slow; when the drying temperature is above 60°C, the products after the reaction may undergo oxidation or agglomeration, thereby affecting the structure and electrocatalytic performance of the composite material. Understandably, the drying can be carried out in an oven or a forced-air drying oven.

[0055] Step S300: The precursor is subjected to carbonization treatment to obtain a composite material, wherein the composite material includes C, P, S, N and Fe. x P.

[0056] In some embodiments, the carbonization treatment includes heating the precursor to 800°C–1100°C in a non-reactive atmosphere at a heating rate of 2°C / min–10°C / min, and holding at that temperature for 2.0h–4.0h. This embodiment can result in a composite material with more three-dimensional pore channels. These three-dimensional pore channels allow oxygen molecules to fully enter the catalyst for oxygen reduction reaction, while the abundant pore structure facilitates the attachment of active sites, increasing the contact area between the catalyst and the electrolyte and oxygen to improve catalytic activity.

[0057] It should be noted that the non-reactive atmosphere involved here includes any atmosphere such as nitrogen or argon. After isothermal treatment, it can be cooled to room temperature naturally or by quenching.

[0058] Sample 1 is prepared by means of the following steps:

[0059] (1) Take 0.44g of ferrous sulfate heptahydrate and 0.76g of 1,10-phenanthroline and place them in a beaker containing 100mL of methanol. After the ferrous sulfate heptahydrate and 1,10-phenanthroline are evenly dispersed in methanol, add 0.3g of hexachlorotriphosphazene and 0.68g of 4,4-dihydroxydiphenyl sulfone. After the hexachlorotriphosphazene and 4,4-dihydroxydiphenyl sulfone are evenly dispersed in methanol, add 1mL of triethylamine to obtain a mixture.

[0060] (2) The beaker containing the mixture was placed on a magnetic stirrer and stirred at 600 rpm for 18 hours to ensure that ferrous sulfate heptahydrate, 1,10-phenanthroline, hexachlorotriphosphazene, and 4,4-dihydroxydiphenyl sulfone reacted completely. The product was then washed sequentially with methanol and ultrapure water at 11,500 rpm by centrifugation. After centrifugation and washing, the product was placed in a 60°C forced-air drying oven until it dried to obtain the precursor.

[0061] (3) Place the precursor in a tube furnace and heat it to 900°C at a rate of 5°C / min under an argon atmosphere. Hold it at that temperature for 3 hours and then let it cool naturally to room temperature to obtain sample 1.

[0062] Sample 2 is prepared by the following steps:

[0063] (1) Take 0.44g of ferrous sulfate heptahydrate and 0.76g of 1,10-phenanthroline and place them in a beaker containing 100mL of methanol. After the ferrous sulfate heptahydrate and 1,10-phenanthroline are evenly dispersed in methanol, add 0.3g of hexachlorotriphosphazene and 0.68g of 4,4-dihydroxydiphenyl sulfone. After the hexachlorotriphosphazene and 4,4-dihydroxydiphenyl sulfone are evenly dispersed in methanol, add 1mL of triethylamine to obtain a mixture.

[0064] (2) The beaker containing the mixture was placed on a magnetic stirrer and stirred at 600 rpm for 18 hours to ensure that ferrous sulfate heptahydrate, 1,10-phenanthroline, hexachlorotriphosphazene, and 4,4-dihydroxydiphenyl sulfone reacted completely. The product was then washed sequentially with methanol and ultrapure water at 11,500 rpm by centrifugation. After centrifugation and washing, the product was placed in a 60°C forced-air drying oven until it dried to obtain the precursor.

[0065] (3) Place the precursor in a tube furnace and heat it to 1000℃ at a heating rate of 5℃ / min under an argon atmosphere. After holding it at that temperature for 3 hours, allow it to cool naturally to room temperature to obtain sample 2.

[0066] Sample 3 is prepared by means of the following steps:

[0067] (1) Take 0.44g of ferrous sulfate heptahydrate and 0.76g of 1,10-phenanthroline and place them in a beaker containing 100mL of methanol. After the ferrous sulfate heptahydrate and 1,10-phenanthroline are evenly dispersed in methanol, add 0.3g of hexachlorotriphosphazene, 0.68g of 4,4-dihydroxydiphenyl sulfone and 1ml of triethylamine to obtain a mixed solution.

[0068] (2) The beaker containing the mixture was placed on a magnetic stirrer and stirred at 600 rpm for 18 hours to ensure that ferrous sulfate heptahydrate, 1,10-phenanthroline, hexachlorotriphosphazene, and 4,4-dihydroxydiphenyl sulfone reacted completely. The product was then washed sequentially with methanol and ultrapure water at 11,500 rpm by centrifugation. After centrifugation and washing, the product was placed in a 60°C forced-air drying oven until it dried to obtain the precursor.

[0069] (3) Place the precursor in a tube furnace and heat it to 1100℃ at a heating rate of 5℃ / min under an argon atmosphere. After holding it at that temperature for 3 hours, allow it to cool naturally to room temperature to obtain sample 3.

[0070] It is understood that Sample 1, Sample 2, and Sample 3 are all composite materials prepared using the composite material preparation method provided in the embodiments of this application.

[0071] The composite material includes C, P, S, N, and Fe. x P.

[0072] To demonstrate that the composite material prepared using the method provided in this application comprises C, P, S, N, and Fe, x P, the surface elements of sample 2 were characterized by transmission electron microscopy (TEM), and the results are as follows: Figure 2 As shown, by Figure 2 It can be seen that S, N, and P elements are uniformly distributed on the surface of the carbon substrate, indicating that the composite material prepared by the method provided in the embodiments of this application includes C, P, S, and N elements. Figure 2 It can be seen that the partial distribution characteristics of P element on the carbon substrate are the same as those of Fe element on the carbon substrate, indicating that the composite material prepared by the composite material preparation method provided in the embodiments of this application includes Fe. x P.

[0073] In some embodiments, the composite material includes graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and thiophene sulfur, which can improve the ORR catalytic performance of the composite material.

[0074] Specifically, to investigate the bonding structure and chemical state of each element in the composite material, sample 2 was characterized by X-ray photoelectron spectroscopy (XPS), and the results are shown in Figure 3. In Figure 3, the horizontal axis represents the electron binding energy, and the vertical axis represents the intensity. Figure 3(a) , 3(b) 3(c), 3(d), 3(e), and 3(f) are XPS spectra of the full spectrum, C 1s, N 1s, Fe 2p, P 2p, and S 2p, respectively.

[0075] In Figure 3(c), the peak at 398.21 eV corresponds to pyridine nitrogen, the peak at 399.96 eV corresponds to pyrrole nitrogen, the peak at 401.48 eV corresponds to graphitic nitrogen, and the peak at 403.50 eV corresponds to nitrogen oxides. This indicates that the composite material prepared by the method provided in the embodiments of this application includes four different forms of nitrogen: graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and nitrogen oxides. In Figure 3(f), the peaks at 164.02 eV and 165.32 eV correspond to thiophene sulfide 2p, respectively. 3 / 2 Thiophene sulfide 2p 1 / 2 The peak at 168.91 eV corresponds to sulfur oxide, indicating that the composite material prepared by the method provided in this application includes two different forms of nitrogen: thiophene nitrogen and sulfur oxide. Among them, graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and thiophene nitrogen are ORR active substances, which can significantly improve the ORR catalytic performance of the composite material.

[0076] In Figure 3(b), the peak at 283.21 eV corresponds to CS, the peak at 284.8 eV corresponds to CC, the peak at 286.35 eV corresponds to CP, the peak at 288.35 eV corresponds to CO, the peak at 290.10 eV corresponds to CN, and the peak at 291.89 eV corresponds to the π-π* satellite peak. This is consistent with the elemental distribution characteristics of EDS mentioned above, indicating that N, S, and P elements have been successfully doped into carbon, forming a nitrogen, sulfur, and phosphorus co-doped carbon substrate.

[0077] In Figure 3(d), the peak at 707.64 eV corresponds to the Fe-P bond, which corresponds to the Fe2P and FeP particles present in the sample. The peaks at 711.48 eV and 724.91 eV correspond to Fe 2+ The peaks at 714.60 eV and 728.00 eV correspond to Fe 3+ The peak at 718.13 eV and the peak at 730.99 eV correspond to satellite peaks.

[0078] In Figure 3(e), the peak at 130.47 eV corresponds to PC, the peak at 133.36 eV corresponds to PO, and the peak at 134.52 eV corresponds to P-Fe. Most of the P elements exist in the form of PC bonds, confirming the binding of P elements in the carbon matrix. The presence of PO bonds enhances the charge delocalization of carbon atoms, which is more conducive to the adsorption of oxygen by the composite material.

[0079] This application also provides a composite material, which is prepared using the composite material preparation method described in any of the above embodiments. The composite material includes C, P, S, N, and Fe. x P.

[0080] The composite material includes C, P, S, N, and Fe. x The explanation of P has been detailed in the preparation method of the composite material provided in Example 1 above, and will not be repeated here.

[0081] In this embodiment, electron microscopy (SEM) was used to characterize the morphology of sample 1, sample 2, and sample 3, and the results are as follows: Figure 4(a) , 4(b) As shown in 4(c).

[0082] As shown in Figures 4(b) and 4(c), samples 1, 2, and 3 all possess abundant three-dimensional pore channels and porous structures. These three-dimensional pore channels allow oxygen molecules to fully enter the interior of the composite material for oxygen reduction reaction, while the abundant porous structure facilitates the attachment of active sites, increasing the contact area between the composite material and the electrolyte and oxygen to improve ORR catalytic performance. Furthermore, as shown in Figures 4(b) and 4(c), uniformly distributed nanoparticles without significant aggregation are attached to the carbon substrate of samples 2 and 3, indicating that uniformly distributed nanoparticles without significant aggregation are attached to the carbon substrate of the composite material obtained at carbonization temperatures of 1000℃ and 1100℃, respectively, further confirming the presence of FexP particles.

[0083] In some embodiments, the specific surface area of ​​the composite material is 603 m². 2 / g~818m 2 / g can provide more ORR catalytic active sites.

[0084] In this embodiment, the specific surface area of ​​samples 1, 2, and 3 was tested. Specifically, nitrogen adsorption-desorption isotherm tests were performed using a BET analyzer, and the results are as follows: Figure 5 As shown, Figure 5 In the graph, the horizontal axis represents relative pressure, and the vertical axis represents the amount of gas adsorbed.

[0085] Depend on Figure 5It can be seen that the nitrogen adsorption-desorption isotherms of samples 1, 2, and 3 all exhibit typical type IV adsorption-desorption isotherm characteristics, that is, the adsorption amount rises rapidly in the low-pressure region (P / P0 = 0.0-0.1), and the curve is convex upward, indicating that the samples have a large number of micropores. At the same time, obvious H4 type hysteresis loops appear in the medium-pressure region (P / P0 = 0.3-0.8) and the high-pressure region (P / P0 = 0.9-1.0), indicating that the composite material provided in this application has a large number of mesopores. The specific surface area of ​​samples 1, 2, and 3, calculated by the BET model, is 603 m². 2 / g、818m 2 / g and 800m 2 The larger specific surface area ( / g) provides more active sites, thus improving the ORR catalytic performance of the composite material.

[0086] In some embodiments, the composite material has a hierarchical porous structure.

[0087] In this embodiment of the application, BJH pore size distribution tests were performed on samples 1, 2, and 3. The results are shown in Figure 6, where the horizontal axis represents pore width and the vertical axis represents differential pore volume.

[0088] Depend on Figure 6 It can be seen that samples 1, 2, and 3 are mainly composed of micropores, with mesopores and macropores as secondary components, indicating that the composite material provided by the embodiments of this application has a multi-level pore structure.

[0089] To demonstrate that the composite material provided in this application possesses ORR catalytic performance, electrochemical tests were performed on samples 1, 2, and 3 using cyclic voltammetry. The tests were conducted in a 0.1 mol / L KOH solution at a scan rate of 25 mV / s. The test results are as follows: Figure 7 As shown, Figure 7 In the diagram, the horizontal axis represents voltage, and the vertical axis represents current density.

[0090] Depend on Figure 7 It can be seen that the cyclic voltammetry curves of samples 1, 2, and 3 all showed obvious redox peaks, indicating that the composite material provided in the embodiments of this application has ORR catalytic performance.

[0091] This application embodiment also includes electrochemical tests on samples 1, 2, and 3 using linear scanning voltammetry. The tests were performed in a 0.1 mol / L KOH solution at a scan rate of 5 mV / s. The test results are as follows: Figure 8 As shown, Figure 8 In the diagram, the horizontal axis represents voltage, and the vertical axis represents current density.

[0092] Depend on Figure 8 It can be seen that the starting potential, half-wave potential and limiting current density of sample 2 are the best, indicating that the ORR catalytic performance of the composite material obtained at a carbonization temperature of 1000℃ is the best.

[0093] To demonstrate that the composite material provided in this application exhibits superior stability compared to the platinum-based catalyst, the stability of the platinum-carbon catalyst and sample 2 was tested using a chronoamperometry method. Specifically, the platinum-carbon catalyst and sample 2 were used to catalyze the oxygen reduction reaction at a voltage of 0.4V, and the results are as follows. Figure 9 As shown, Figure 9 In the figure, the horizontal axis represents time, and the vertical axis represents the current retention rate.

[0094] Depend on Figure 9 It can be seen that after the oxygen reduction reaction proceeded for 30,000 seconds, sample 2 maintained 87.8% of the current, while the platinum-carbon catalyst maintained 81.6% of the current, indicating that the stability of the composite material provided in the embodiments of this application is better than that of the platinum-carbon catalyst.

[0095] To demonstrate that the methanol resistance of the composite material provided in this application is superior to that of the platinum-based catalyst, the methanol resistance performance of the platinum-carbon catalyst and sample 2 was tested using a chronoamperometry method. Specifically, the platinum-carbon catalyst and sample 2 were used to catalyze the oxygen reduction reaction at a voltage of 0.4V, and the results are as follows. Figure 10 As shown, Figure 10 In the diagram, the horizontal axis represents time, and the vertical axis represents current.

[0096] Depend on Figure 10 It can be seen that when the oxygen reduction reaction proceeded for 150 s, after methanol solution was added to both the platinum-carbon catalyst and sample 2, the current of sample 2 did not fluctuate significantly, while the current of the platinum-carbon catalyst fluctuated significantly. Compared with the platinum-carbon catalyst, the composite material provided in this application has excellent methanol resistance.

[0097] In some embodiments, the composite material includes graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen, and thiophene sulfur, which can improve the ORR catalytic performance of the composite material.

[0098] The description of the composite material including graphitic nitrogen, pyrrole nitrogen, pyridine nitrogen and thiophene sulfur has been described in detail in the preparation method of the composite material provided in the above embodiments, and will not be repeated here.

[0099] Understandably, the test curve for sample 1 corresponds to the test curve at 900℃ in the attached figure, the test curve for sample 2 corresponds to the test curve at 1000℃ in the attached figure, and the test curve for sample 3 corresponds to the test curve at 1100℃ in the attached figure.

[0100] This application also provides an electrocatalyst, which includes the composite material described in any of the above embodiments.

[0101] In some embodiments, the electrocatalyst is an ORR catalyst.

[0102] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of preparing a composite material, characterized by, The method comprises: mixing an iron source, a nitrogen source, a phosphorus source, a sulfur source and a catalyst in a solvent to obtain a mixed solution; after the iron source, the nitrogen source, the phosphorus source and the sulfur source in the mixed solution are fully reacted, washing and drying the reacted product to obtain a precursor; carburizing the precursor to obtain a composite material; The molar ratio of iron element in the iron source and nitrogen element in the nitrogen source is 1:6, the molar ratio of phosphorus element in the phosphorus source and sulfur element in the sulfur source is 1:1, the iron source includes at least one of ferrous sulfate heptahydrate, ferrous chloride and ferrous nitrate, the phosphorus source includes hexachlorotriphosphazene, the nitrogen source includes 1,10-phenanthroline, the sulfur source includes 4,4-dihydroxydiphenyl sulfone, and the composite material includes C, P, S, N and Fe x P; the carburizing process comprises: heating the precursor to 800-1100℃ at a heating rate of 2-10℃ / min in a non-reactive atmosphere and keeping the temperature for 2.0-4.0h.

2. The method of claim 1, wherein the step of mixing the first and second materials is performed at a temperature of from about 20°C to about 100°C. the catalyst comprises triethylamine; and / or, the solvent comprises methanol.

3. The method of claim 1, wherein the step of mixing the first and second materials is performed at a temperature of from about 20°C to about 100°C. the washing process comprises: sequentially washing the reacted product with the solvent and ultrapure water; and / or, the drying temperature is 40-60℃.

4. The method of claim 1, wherein the composite material is prepared by a method comprising: the composite material comprises graphite nitrogen, pyrrole nitrogen, pyridine nitrogen and thiophene sulfur.

5. A composite material, characterized by, The composite material is prepared using the method of claim 1 to 4 for the preparation of a composite material comprising C, P, S, N and Fe x P.

6. The composite material of claim 5, wherein, The specific surface area of the composite material is 603 m 2 / g ~ 818 m 2 / g; and / or the composite material has a hierarchical pore structure.

7. The composite material of claim 5, wherein, the composite material has methanol resistance; and / or, the composite material comprises graphite nitrogen, pyrrole nitrogen, pyridine nitrogen and thiophene sulfur.

8. An electrocatalyst characterized in that, the electrocatalyst comprises the composite material according to any one of claims 5-7.

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