Sulfur-doped fe3o4-feni3 / cn bimetallic composite catalyst, preparation method thereof and application thereof in electrolytic water oxygen evolution

Abstract

The application belongs to the field of water oxidation catalyst preparation, and discloses a sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst, a preparation method thereof and application of the catalyst in electrolytic water oxygen evolution. Polyaniline, ferric nitrate, nickel nitrate and sublimed sulfur are mixed, and high-temperature pyrolysis is performed, wherein the molar ratio of ferric nitrate to nickel nitrate is 3:1 to 1:3; the sulfur-doped bimetallic composite catalyst Fe3O4-FeNi3-S / CN is prepared by high-temperature pyrolysis at 400-700 DEG C. The application investigates the influence of the amount of sublimed sulfur on the FeNi3 crystalline phase of the catalyst, finds that the activity of the catalyst increases with the increase of the FeNi3 crystalline phase and the catalyst cannot be over-sulfided into sulfide, and finally realizes good synergistic catalytic effect, so as to optimize the performance and stability of the oxygen evolution reaction.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of water oxidation catalyst preparation, and particularly relates to a preparation method and product and application of a sulfur-doped bimetallic composite catalyst. BACKGROUND

[0002] Hydrogen energy has high energy density and environmental friendliness, and is widely considered as a promising energy carrier to realize energy upgrading. Among various hydrogen production technologies, electrocatalytic water splitting stands out due to its zero pollution, high product purity, and simple operation. Generally, water splitting involves two half-reactions: anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). Compared with HER, OER has higher energy demand and thermodynamic barrier due to its slow multi-proton coupled electron transfer process. Although noble metal-based electrocatalysts (such as RuO2 and IrO2) have shown impressive activity in OER, their widespread application is hindered by their scarcity and durability. Therefore, it is urgent to develop earth-abundant transition metal-based electrocatalysts to replace noble metal-based electrocatalysts, thereby further advancing large-scale water splitting for hydrogen production.

[0003] So far, efforts have been made to develop non-noble metal OER catalysts with excellent performance and low price, such as Cr, Co, Fe and other compounds, which are considered as valuable candidates to improve the activity of oxygen evolution reaction. Among non-noble metal catalysts, Ni-based and Fe-based catalysts have attracted much attention due to their abundant world reserves. In recent years, combining two or more catalytic materials to construct heterostructures has become an effective strategy to improve catalyst activity. The formation of heterostructures not only effectively promotes interface electron transfer and adjusts the adsorption free energy of reaction species, but also produces new interface structures by changing the composition and crystal phase of the structure, achieving efficient oxygen evolution catalytic function. In addition, preparing multi-component transition metals (such as Co, Ni and Fe) by element doping is also a good engineering strategy. By controlling and designing defect engineering to adjust the active center, great success has been achieved, showing good electrocatalytic activity, thereby improving the oxygen evolution activity of OER.

[0004] The purpose of adding sublimed sulfur for pyrolysis in the art is to generate sulfides. The present application first studies the effect of sulfur on the crystallinity of FeNi3. When the catalyst is not doped with sublimed sulfur, the prepared FeNi3 has low crystallinity and is in a metastable state. The purpose of adding sublimed sulfur is not only to improve the adsorption effect of the electrode material, but also to improve the crystallinity of FeNi3 in the catalyst, thereby optimizing the performance and stability of the oxygen evolution reaction. However, the main problem to be solved at present is how much sublimed sulfur should be added during preparation to ensure that the crystallinity of FeNi3 increases without being over-sulfidized into sulfides. Therefore, this paper studies the optimal optimization ratio of different amounts of sublimed sulfur to improve the crystallinity of FeNi3 alloy in the catalyst, which has not been reported in the current research. SUMMARY

[0005] To solve the above problems, the present application provides a preparation method of a sulfur-doped bimetallic composite catalyst. By optimizing the amount of sulfur, the crystallinity of FeNi3 can be increased without being over-sulfidized into sulfides, and the oxygen evolution catalytic activity of the catalyst can be improved.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A preparation method of a sulfur-doped Fe3O4-FeNi3 / CN catalyst, comprising,

[0008] (1) Weigh iron nitrate, nickel nitrate and sublimed sulfur and mix them in ethanol solvent, and stir them uniformly with a magnetic stirrer to obtain a yellow solution.

[0009] (2) Weigh polyaniline and place it in the yellow solution, stir it uniformly, dry it, and obtain a black substance; high-temperature calcination to obtain a Fe3O4-FeNi3-S / CN catalyst

[0010] The molar ratio of iron nitrate to nickel nitrate is 3:1 to 1:3, and the calcination temperature is 500°C. Further preferably, the molar ratio of iron nitrate to nickel nitrate is 1:1.

[0011] The total metal molar amount is 2 mmol and the polyaniline mass amount is 0.2 g. Polyaniline not only acts as a dispersion medium and carrier, but also has the effect of protecting and reducing metals. During high-temperature calcination, polyaniline generates reducing gases such as NO and CO, which causes the metal ions embedded therein to undergo a reduction reaction, allowing them to exist in part as alloys. Moreover, the polyaniline after high-temperature calcination also has the purpose of protecting active metals and improving reaction stability.

[0012] The high-temperature pyrolysis temperature is 400-700°C, the pyrolysis time is 3h, and the pyrolysis atmosphere is nitrogen. Further preferably, the high-temperature pyrolysis temperature is 500°C.

[0013] The molar ratio of the total moles of metal and sublimed sulfur is 2:0.5-2, and further preferably 2:1.

[0014] When the amount of sublimed sulfur is less than the amount of sublimed sulfur when the molar ratio of the total moles of metal and sublimed sulfur is 2:1, the optimization of the catalyst does not reach the best degree, and the crystallinity of the FeNi3 alloy does not increase to the maximum degree; when the amount of sublimed sulfur is higher than the amount, the FeNi3 alloy will be sulfided by too much sublimed sulfur, so that the FeNi3 alloy disappears, and the oxygen evolution catalytic activity is reduced.

[0015] A further object of the present application is to overcome the deficiencies in the prior art and provide a product prepared by the preparation method of the bimetallic composite catalyst Fe3O4-FeNi3 / CN.

[0016] Another object of the present application is to overcome the deficiencies in the prior art and provide a product prepared by the preparation method of the sulfur-doped bimetallic composite catalyst Fe3O4-FeNi3-S / CN as an application in an oxygen reduction catalyst.

[0017] The present application has the following advantages:

[0018] The present application provides a preparation method of a sulfur-doped bimetallic composite catalyst Fe3O4-FeNi3 / CN, which comprises compounding ferric nitrate, nickel nitrate and polyaniline with sublimed sulfur to achieve good synergistic catalytic effect; the effects of the molar amount of ferric nitrate and nickel nitrate and the calcination temperature on the catalyst are investigated by optimizing the compounding ratio; then, the Fe3O4-FeNi3-S / CN series catalyst is prepared by introducing sublimed sulfur into the raw materials, and the effect of the amount of sublimed sulfur on the structure and performance of the catalyst is investigated. The main crystal phase structure of the prepared catalyst is FeNi3 and Fe3O4, and with the gradual increase of the amount of sublimed sulfur, the FeNi3 crystal phase shown in the XRD pattern shows a trend of first increasing and then decreasing. The activity of the catalyst also increases with the increase of the FeNi3 crystal phase. Among them, the Fe1Ni1-S1 / PANI-500 catalyst has the best crystallinity and the best oxygen evolution catalytic activity, and the overpotential is only 336mV, and the 50h attenuation rate is only 1.6%. -2 BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:​

[0020] Figure 1 XRD comparison chart of catalysts in embodiments 1, 3, 5 of the present application.

[0021] Figure 2 XRD comparison chart of catalysts in embodiments 1, 2, 14 of the present application.

[0022] Figure 3 LSV comparison chart of samples with different metal molar ratios in embodiments 1, 3, 4, 5, 6 of the present application.

[0023] Figure 4 LSV comparison chart of samples with different temperatures in embodiments 1, 7, 8, 9 of the present application.

[0024] Figure 5 LSV comparison chart of samples with different sulfur contents in embodiments 2, 10, 11, 12, 13, 14 of the present application.

[0025] Figure 6 V-t curve chart of samples in embodiments 1, 2, 10 after 50h test at 10mA cm -2 DETAILED DESCRIPTION

[0026] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0027] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given below. In other instances, well-known methods have not been described in detail in order to avoid obscuring the present application. Therefore, the present application is not intended to be limited by the specific embodiments disclosed below.

[0028] Secondly, the term "one embodiment" or "an embodiment" as used herein means that a particular implementation can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Furthermore, the following

[0029] Water oxidation reaction performance evaluation in embodiments of the present application:

[0030] Test by electrochemical workstation:

[0031] First, polish the glassy carbon electrode (area is 0.126cm 2 ​) to its surface, and rinsed with deionized water and ethanol, and dried at room temperature. 2 mg of catalyst and 2 mg of activated carbon (for accuracy) were placed in a sample tube, 950 μL of anhydrous ethanol and 50 μL of Nafion solution were added, and after ultrasonic dispersion, 15.8 μL of ink was dropped onto the surface of the glassy carbon electrode, and dried at room temperature, and the loading of catalyst on the surface of the electrode was 0.25 mg·cm -2 ;

[0032] The electrochemical performance of the catalyst was tested at room temperature in a three-electrode system of 1 mol L -1 of KOH solution. The catalyst-loaded glassy carbon electrode (GC) was used as the working electrode, the Ag / AgCl electrode saturated with KCl was used as the reference electrode, and the carbon rod was used as the counter electrode.

[0033] The RDE rotation speed of LSV testing was 1600 rpm, the test voltage range was -0.023-0.977 V, and the scanning speed was 5 mV s -1 .

[0034] From the LSV polarization curve, the important parameters of the OER catalyst performance can be obtained: the overpotential at 10 mA cm -2 .

[0035] From the V-t constant current curve, the decay rate of the catalyst after long-term testing can be obtained.

[0036] The lower the overpotential at 10 mA cm -2 , the smaller the decay rate after long-term testing, indicating that the catalyst has higher electrocatalytic water oxidation activity.

[0037] The raw materials in the embodiments of the application are all ordinary commercially available products.

[0038] Example 1

[0039] Preparation and testing of polyaniline material:

[0040] (1) 20 mmol of aniline was weighed into a beaker, 50 mL of 2 mol L -1 of HCl was poured into the beaker, and the mixture was stirred uniformly with a magnetic stirrer, and cooled to 0-5℃ in an ice-water mixture to obtain a colorless solution A;

[0041] 20 mmol of ammonium persulfate was weighed into a beaker, 50 mL of deionized water was poured into the beaker, and the mixture was stirred uniformly with a magnetic stirrer to obtain a colorless transparent solution B;

[0042] The B solution was placed in a constant pressure funnel, and under the condition of 0-5℃, 1 mL min -1The solution A is slowly added dropwise into the solution B, while continuing to stir the solution A, a green solution C is obtained after 6h;

[0043] Then, the solution C is centrifuged and washed with anhydrous ethanol three times, the green precipitate is collected and dried in a vacuum drying oven at 60℃ overnight.

[0044] The obtained green product is ground in an agate mortar to obtain a green powder, which is the polyaniline.

[0045] (2) Preparation of Fe3O4-FeNi3 / CN material:

[0046] 1 mmol of iron nitrate and 1 mmol of nickel nitrate are weighed into a beaker, the total metal molar amount is 2 mmol, 20 mL of methanol is poured into the beaker, and the solution is stirred uniformly with a magnetic stirrer to obtain a yellow solution D.

[0047] 200 mg of polyaniline is weighed into the yellow solution D and stirred with a magnetic stirrer for 3h to obtain a black solution E.

[0048] The solution E is placed in a 60℃ water bath to dry completely to obtain a black powder F.

[0049] Then, the black powder F is calcined in a tube furnace under a nitrogen atmosphere at 500℃ for 3h to obtain a black product G.

[0050] The obtained black product G is ground in an agate mortar to obtain a black powder, which is Fe3O4-FeNi3 / CN, and the final product is named Fe1Ni1 / PANI-500.

[0051] After the above catalyst is prepared into a working electrode for electrocatalytic water oxidation test, see Figure 3 , Figure 6 ;

[0052] It can be seen that the Fe1Ni1 / PANI-500 catalyst has the highest electrocatalytic water oxidation performance, and the overpotential of electrocatalytic water oxidation is 336mV at 10mAcm -2 , and the decay rate after 50h is 4.1%.

[0053] Example 2

[0054] Preparation of Fe3O4-FeNi3-S / CN material:

[0055] 1 mmol of iron nitrate, 1 mmol of nickel nitrate and 1 mmol of sulfur are weighed into a beaker, 20 mL of methanol is poured into the beaker, and the solution is stirred uniformly with a magnetic stirrer to obtain a yellow solution ①.

[0056] Take 200 mg of polyaniline and put it into yellow solution ①, and stir it with a magnetic stirrer for 3 h, then put it into a water bath at 60°C to dry completely, and obtain the black material; put it into a tube furnace under nitrogen atmosphere at 500°C and calcine it for 3 h to obtain black product ②;

[0057] Put the obtained black product ② into an agate mortar and grind it evenly to obtain black powder, which is Fe3O4-FeNi3-S / CN, and the final product is named as Fe1Ni1-S1 / PANI-500.

[0058] After preparing the above catalyst into a working electrode for electrocatalytic water oxidation test, see Figure 5 , Figure 6 ;

[0059] It can be seen that the Fe1Ni1-S1 / PANI-500 catalyst has the highest electrocatalytic water oxidation performance, and the overpotential of electrocatalytic water oxidation is 298 mV at 10 mA cm -2 , and the decay rate after 50 h is 1.6%.

[0060] Example 3

[0061] Preparation of Fe3O4-FeNi3 / CN material with a molar ratio of iron nitrate to nickel nitrate of 2:1:

[0062] The same as example 1, the same synthesis method is used, the molar amount of iron nitrate and nickel nitrate is changed to 1.3 mmol and 0.7 mmol, and the others remain unchanged, and the final product is named as Fe2Ni1 / PANI-500.

[0063] After preparing the above catalyst into a working electrode for electrocatalytic water oxidation test, see Figure 3 , the overpotential of electrocatalytic water oxidation of Fe2Ni1 / PANI-500 is 388 mV at 10 mA cm -2 .

[0064] Example 4

[0065] Preparation of Fe3O4-FeNi3 / CN material with a molar ratio of iron nitrate to nickel nitrate of 3:1:

[0066] The same as example 1, the same synthesis method is used, the molar amount of iron nitrate and nickel nitrate is changed to 1.5 mmol and 0.5 mmol, and the others remain unchanged, and the final product is named as Fe3Ni1 / PANI-500.

[0067] After preparing the above catalyst into a working electrode for electrocatalytic water oxidation test, see Figure 3 , the overpotential of electrocatalytic water oxidation of Fe3Ni1 / PANI-500 is 388 mV at 10 mA cm -2The overpotential of the electrocatalytic water oxidation of Fe1Ni2 / PANI-500 is 540 mV at 10 mA cm-2.

[0068] Example 5

[0069] Preparation of Fe3O4-FeNi3 / CN material with the molar ratio of iron nitrate to nickel nitrate being 1:2:

[0070] The same synthesis method as in Example 1 was used, the molar amount of iron nitrate and nickel nitrate was changed to 0.7 mmol and 1.3 mmol, and other conditions were unchanged. The final product was named Fe1Ni2 / PANI-500.

[0071] After the above catalyst was prepared into a working electrode for electrocatalytic water oxidation test, it was found that Figure 3 The overpotential of the electrocatalytic water oxidation of Fe1Ni2 / PANI-500 is 407 mV at 10 mA cm-2. -2

[0072] Figure 1 The XRD comparison chart of the catalysts in Examples 1, 3 and 5 shows that the diffraction peaks at 2θ of 18.9°, 30.8°, 35.4°, 43.1°, 53.6°, 57.0° and 62.3° all belong to the (111), (220), (311), (400), (422), (511) and (440) crystal planes of Fe3O4 (PDF # 87-2337); and the diffraction peaks at 2θ of 44.4°, 51.8° and 76.2° correspond to the (111), (200) and (220) crystal planes of FeNi3 (PDF # 99-0073), respectively. This indicates that Fe3O4 and FeNi3 exist in the catalysts. In these catalysts, as the proportion of nickel element gradually increases, the FeNi3 characteristic diffraction peak gradually sharpens, the Fe3O4 characteristic diffraction peak gradually broadens, and when the amount of nickel element is 1 mmol, the FeNi3 characteristic diffraction peak has the maximum peak intensity. In addition, no diffraction peak of polyaniline-derived carbon is observed in the XRD spectrum, because the peak intensity is low, which makes it difficult to detect.

[0073] Example 6

[0074] Preparation of Fe3O4-FeNi3 / CN material with the molar ratio of iron nitrate to nickel nitrate being 1:3:

[0075] The same synthesis method as in Example 1 was used, the molar amount of iron nitrate and nickel nitrate was changed to 0.7 mmol and 1.3 mmol, and other conditions were unchanged. The final product was named Fe1Ni2 / PANI-500.

[0076] ​The catalyst was prepared into working electrode for electrocatalytic water oxidation test, see Figure 3 , the overpotential of Fe1Ni3 / PANI-500 electrocatalytic water oxidation was 535 mV at 10 mA cm -2 .

[0077] Example 7

[0078] Preparation and test of Fe3O4-FeNi3 / CN catalyst with calcination temperature of 400℃:

[0079] The same as example 1, the same synthesis method was used, the calcination temperature of Fe1Ni1 / PANI-T was 400℃, and the others were unchanged, and the final product was named Fe1Ni1 / PANI-400.

[0080] The catalyst was prepared into working electrode for electrocatalytic water oxidation test, see Figure 4 , the overpotential of Fe1Ni1 / PANI-400 electrocatalytic water oxidation was 505 mV at 10 mA cm -2 .

[0081] Example 8

[0082] Preparation and test of Fe3O4-FeNi3 / CN catalyst with calcination temperature of 600℃:

[0083] The same as example 1, the same synthesis method was used, the calcination temperature of Fe1Ni1 / PANI-T was 600℃, and the others were unchanged, and the final product was named Fe1Ni1 / PANI-600.

[0084] The catalyst was prepared into working electrode for electrocatalytic water oxidation test, see Figure 4 , the overpotential of Fe1Ni1 / PANI-600 electrocatalytic water oxidation was 369 mV at 10 mA cm -2 .

[0085] Example 9

[0086] Preparation and test of Fe3O4-FeNi3 / CN catalyst with calcination temperature of 700℃:

[0087] The same as example 1, the same synthesis method was used, the calcination temperature of Fe1Ni1 / PANI-T was 700℃, and the others were unchanged, and the final product was named Fe1Ni1 / PANI-700.

[0088] The catalyst was prepared into working electrode for electrocatalytic water oxidation test, see Figure 4 , the overpotential of Fe1Ni1 / PANI-700 electrocatalytic water oxidation was 369 mV at 10 mA cm -2The overpotential is 401mV.

[0089] Example 10

[0090] Preparation and testing of Fe3O4-FeNi3-S / CN catalyst with a sulfur content of 0.5 mmol:

[0091] Same as Example 2, using the same synthesis method, with a sublimation amount of 0.5 mmol, and all other parameters remaining unchanged, the final product was named Fe1Ni1-S. 0.5 / PANI-500.

[0092] After preparing the above catalyst into a working electrode and conducting electrocatalytic water oxidation tests, see [link to relevant documentation]. Figure 5 , Figure 6 Fe1Ni1-S 0.5 / PANI-500 electrocatalytic water oxidation at 10 mA cm⁻¹ -2 The overpotential was 322mV, and the decay rate after 50h was 3.0%.

[0093] Example 11

[0094] Preparation and testing of Fe3O4-FeNi3-S / CN catalyst with a sulfur content of 0.75 mmol:

[0095] Same as Example 2, using the same synthesis method, with a sublimation amount of 0.75 mmol, and all other parameters remaining unchanged, the final product was named Fe1Ni1-S. 0.75 / PANI-500.

[0096] After preparing the above catalyst into a working electrode and conducting electrocatalytic water oxidation tests, see [link to relevant documentation]. Figure 5 Fe1Ni1-S 0.75 / PANI-500 electrocatalytic water oxidation at 10 mA cm⁻¹ -2 The overpotential is 317mV.

[0097] Example 12

[0098] Preparation and testing of Fe3O4-FeNi3-S / CN catalyst with a sulfur content of 1.25 mmol:

[0099] Same as Example 2, using the same synthesis method, with a sublimation amount of 1.25 mmol, and all other parameters remaining unchanged, the final product was named Fe1Ni1-S. 1.25 / PANI-500.

[0100] After preparing the above catalyst into a working electrode and conducting electrocatalytic water oxidation tests, see [link to relevant documentation]. Figure 5 Fe1Ni1-S 1.25 / PANI-500 electrocatalytic water oxidation at 10 mA cm⁻¹ -2 The overpotential is 303mV.

[0101] Example 13

[0102] Preparation and testing of Fe3O4-FeNi3-S / CN catalyst with 1.5 mmol of sulfur:

[0103] Same as Example 2, using the same synthesis method, but with a sublimation amount of 1.5 mmol, and all other parameters remaining unchanged. The final product was named Fe1Ni1-S. 1.5 / PANI-500.

[0104] After preparing the above catalyst into a working electrode and conducting electrocatalytic water oxidation tests, see [link to relevant documentation]. Figure 5 Fe1Ni1-S 1.5 / PANI-500 electrocatalytic water oxidation at 10 mA cm⁻¹ -2 The overpotential is 314mV.

[0105] Example 14

[0106] Preparation and testing of Fe3O4-FeNi3-S / CN catalyst with 2 mmol of sulfur:

[0107] Same as Example 2, using the same synthesis method, with a sublimation amount of 2 mmol, and all other parameters remaining unchanged, the final product was named Fe1Ni1-S2 / PANI-500.

[0108] After preparing the above catalyst into a working electrode and conducting electrocatalytic water oxidation tests, see [link to relevant documentation]. Figure 5 Fe1Ni1-S2 / PANI-500 electrocatalytic water oxidation at 10 mA cm⁻¹ -2 The overpotential is 344mV.

[0109] XRD comparison images of Fe1Ni1 / PANI-500, Fe1Ni1-S1 / PANI-500, and Fe1Ni1-S2 / PANI-500 prepared in Examples 1, 2, and 14 of this invention are shown below. Figure 2 It can be seen that after adding 1 mmol of distilled sulfur to the catalyst, the diffraction peaks belonging to FeNi3 became sharper, and the peak intensity increased significantly, indicating an increase in crystallinity and a transformation from a metastable to a highly stable structure. After adding 2 mmol of distilled sulfur, the catalyst exhibited a transitional sulfidation state, with the diffraction peaks belonging to FeNi3 almost disappearing, and instead, diffraction peaks of the byproducts Ni3S2 and (Fe,Ni)9S8 appearing. In the oxygen evolution electrochemical test, when the current density was 10 mA cm⁻¹... -2At this time, the overpotential of Fe1Ni1 / PANI-500, Fe1Ni1-S1 / PANI-500 and Fe1Ni1-S2 / PANI-500 is 336 mV, 298 mV and 344 mV respectively, which indicates that appropriate sulfurization can increase the crystallinity of FeNi3 in the catalyst and is beneficial to the improvement of oxygen evolution activity, while the consequence of transition sulfurization of the catalyst is the appearance of by-products Ni3S2 and (Fe,Ni)9S8, thus leading to the decline of the catalytic activity of the catalyst. Moreover, when the sulfur dosage is greater than 1 mmol, the performance of the catalyst appears to be attenuated, which is due to the decrease of FeNi3 and the increase of by-products caused by excessive sulfurization.

[0110] In the Fe1Ni1 / PANI-500, Fe1Ni1-S1 / PANI-500 and Fe1Ni1-S2 / PANI-500 prepared in embodiments 1, 2 and 10 of the present application, 0.5 The constant current test of Fe1Ni1 / PANI-500, Fe1Ni1-S1 / PANI-500 and Fe1Ni1-S2 / PANI-500 for 50 h under 1 mol / L KOH (10 mA / cm2) is shown in the following figure: -1 KOH (10 mA / cm2) -2 ) is shown in the following figure: Figure 5 After the sulfur dosage in the catalyst Fe1Ni1 / PANI-500 is gradually increased to 1 mmol, the attenuation rate of the catalyst is reduced from 4.1% to 1.6%, and the catalytic stability is obviously increased.

[0111] The present application realizes good synergistic catalytic effect by compounding ferric nitrate, nickel nitrate, sublimed sulfur and polyaniline, and at the same time, the compounding ratio and the calcination temperature are optimized to achieve the best water oxidation performance.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and all of them should be covered in the scope of the present application.

Claims

1. A method for preparing a sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst, characterized in that: (1) Dissolve iron salt, nickel salt and sublimed sulfur in alcohol solvent and stir until homogeneous to obtain solution A; (2) Disperse polyaniline in solution A and stir until homogeneous to obtain a black suspension solution B; (3) Dry the black suspension B and pyrolyze it at a high temperature of 400~700 °C to obtain Fe3O4-FeNi3-S / CN; The molar ratio of iron salt to nickel salt is 1:1; the molar ratio of total metals in iron salt and nickel salt to sublimed sulfur is 2:0.5~1.

2. The preparation method of the sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst as described in claim 1, characterized in that: The iron salt is ferric nitrate; the nickel salt is nickel nitrate.

3. The preparation method of the sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst as described in claim 2, characterized in that: The total molar ratio of iron and nickel salts to sublimed sulfur is 2:

1.

4. The preparation method of the sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst as described in claim 2, characterized in that: The high-temperature pyrolysis temperature was 500 ℃, the pyrolysis time was 3 h, and the pyrolysis atmosphere was nitrogen.

5. The preparation method of the sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst as described in claim 2, characterized in that: The total molar amount of iron and nickel salts was 2 mmol to 0.2 g of polyaniline.

6. The sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst prepared by the method according to any one of claims 1-5.

7. The application of the sulfur-doped Fe3O4-FeNi3 / CN bimetallic composite catalyst prepared by the method according to any one of claims 1-5 in oxygen evolution by water electrolysis.

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