A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material, preparation method and application thereof

Abstract

The present invention relates to the fields of energy materials and electrochemical technology, and specifically to a bifunctional catalyst composed of a composite of iron phthalocyanine and cobalt nickel hydroxide layered materials, a preparation method, and its application. This method uses iron phthalocyanine (FePc), a cobalt salt, and a nickel salt as metal sources, and employs an ultrasound-assisted strong base precipitation method to prepare the composite catalyst in situ in a single step at room temperature. This method features a simple preparation process, mild synthesis conditions, a wide range of raw material sources, and low cost. Under alkaline conditions, the composite catalyst exhibits excellent electrocatalytic performance and has great application prospects.

Description

Technical Field

[0001] The present invention relates to the field of energy materials and electrochemical technology, and in particular to a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials, a preparation method and applications thereof. Background Art

[0002] The rapid depletion of fossil energy sources has led to serious environmental problems and energy shortages, prompting research on a range of green energy conversion and storage technologies. Compared with other batteries, zinc-air batteries offer significant advantages, including low cost, environmental friendliness, long charge-discharge life, and high safety. However, battery performance remains suboptimal due to the sluggish kinetics of the oxygen reduction reaction (ORR) during discharge and the oxygen evolution reaction (OER) during charge at the air electrode. To overcome these barriers, high-performance ORR and OER catalysts are required. Currently, the noble metal Pt is considered the most effective ORR catalyst, but its OER activity is poor. The noble metals Ir and Ru are excellent OER catalysts, but their ORR activity is poor, limiting their ability to function as single catalysts. Furthermore, noble metal catalysts also have disadvantages such as high cost and poor stability. Therefore, the rational design of cost-effective, highly active, and highly stable bifunctional ORR / OER electrocatalysts is crucial for the practical application of zinc-air batteries.

[0003] At present, researchers have developed many materials as bifunctional oxygen electrode catalysts, such as heteroatom-doped carbon nanomaterials, transition metal compounds, etc. Among them, iron phthalocyanine (FePc) materials with N-coordinated iron single atoms are considered to be one of the most effective non-precious metal ORR catalysts, but their OER catalytic performance is not ideal. For OER, transition metal (hydr)oxides are one of the most promising non-precious metal catalysts, especially layered double hydroxides (LDHs) with a layered structure. Effectively combining the two materials is a feasible means to synergistically improve the ORR / OER catalytic activity. LDH and FePc composites are often directly mixed with LDH and commercial iron phthalocyanine by means of mechanical ball milling, etc., because commercial FePc particles are large and have uneven morphology. At the same time, FePc particles and LDH nanosheets are in point-to-point contact, the bonding tightness between the two is poor, and the catalytic performance and stability of the composite material are poor. Therefore, it is necessary to find a suitable method to obtain high-performance LDH and FePc composites.

[0004] Chinese invention patent CN202010758587.8 discloses a preparation method and application of a heterogeneous structured iron / cobalt bimetallic phthalocyanine electrocatalyst, and the preparation method includes: using a solvent thermal method to phase-transform the bimetallic phthalocyanine to composite the bimetallic phthalocyanine. Chinese invention patent application CN202310766027.0 discloses a preparation method and application of a metal sulfide composite bifunctional electrocatalyst. The preparation method of the metal sulfide composite material includes: dissolving graphene oxide, a cobalt source, a nickel source, and a sulfur source and then hydrothermally obtaining a metal sulfide composite material. The application scenarios of the above technical solutions are all zinc-air batteries. It should be pointed out that both of the above technical solutions require the use of a solvent thermal method, which has high energy consumption and the particle size of the crystallized composite material is not easy to control. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of how to effectively compound two materials to obtain layered double hydroxides (LDHs) with a layered structure, thereby synergistically improving the ORR / OER catalytic activity. A bifunctional catalyst composite of iron phthalocyanine and cobalt nickel hydroxide layered materials, a preparation method and its application are provided.

[0006] In order to achieve the above object, the present invention discloses a method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material, comprising the following steps:

[0007] S1, uniformly dispersing cobalt salt and nickel salt in an organic solvent to obtain a dispersion;

[0008] S2, slowly adding iron phthalocyanine powder to the dispersion in step S1, and sonicating for 0.1 to 60 hours;

[0009] S3, rapidly injecting the dispersion obtained after ultrasonication in step S2 into the strong alkaline solution, injecting 100 to 1000 μL each time until the dispersion is completely injected to obtain a mixed solution;

[0010] S4, ultrasonically treating the mixed solution obtained in step S3 for 0.1 to 80 hours, washing, centrifuging, and drying after the ultrasonication to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which is recorded as FePc-LDH.

[0011] In step S1, the cobalt salt is any one of cobalt chloride, cobalt nitrate, and cobalt sulfate, or a mixture of two or more thereof; the nickel salt is any one of nickel chloride, nickel nitrate, and nickel sulfate, or a mixture of two or more thereof; and the organic solvent is any one of methanol, ethanol, and N,N-dimethylformamide, or a mixture of two or more thereof.

[0012] In step S1, the molar ratio of the cobalt salt to the nickel salt is 3:2.

[0013] In the step S2, the dispersion amount of iron phthalocyanine is 2 to 200 mg / mL.

[0014] In step S3, the strong alkaline solution is any one of lithium hydroxide, sodium hydroxide, and potassium hydroxide, or a mixture of two or more thereof.

[0015] In step S3, the molar concentration of the strong base solution is 0.1 to 10 mol / L.

[0016] In step S4, the solvent used for washing is any one of acetone, ethanol, and deionized water, or a mixture of two or more thereof.

[0017] In step S4, the drying method is any one of ordinary air oven drying, vacuum drying, freeze drying, or a combination of two or more thereof, and the drying time is 1 to 144 hours.

[0018] The invention also discloses a dual-function catalyst prepared by adopting the preparation method and composited with iron phthalocyanine and cobalt nickel hydroxide layered materials.

[0019] Compared with the prior art, the present invention has the following advantages: the present invention uses a one-step ultrasound-assisted room temperature precipitation method to compound iron phthalocyanine and cobalt-nickel layered double hydroxide. This composite design promotes synergistic interaction between the iron, cobalt and nickel metals, increases the tightness of the bond between the two materials, effectively improves the bidirectional catalytic performance of oxygen reduction and oxygen evolution, and prolongs the catalytic life. The material preparation process is simple, the synthesis conditions are mild, the raw materials are widely available, the cost is low, it is environmentally friendly, and the reproducibility is high. The composite catalyst has excellent electrocatalytic performance and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 TEM image of the iron phthalocyanine and cobalt nickel layered double hydroxide composite material prepared in Example 1;

[0021] Figure 2 The X-ray diffraction patterns of the materials prepared in Example 1 and Comparative Example 1;

[0022] Figure 3 1 is a Fourier transform infrared spectrum of the composite materials prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0023] Figure 4 The linear sweep voltammetry (LSV) curves of the OER of the composite materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 under 1 M KOH conditions are shown;

[0024] Figure 5 2 is a linear sweep voltammetry (LSV) curve of ORR of the composite materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 under 0.1 M KOH conditions.

[0025] Figure 6 The linear sweep voltammetry (LSV) curves of the OER of the composite materials prepared in Example 1, Example 2, and Example 3 under 1 M KOH conditions are shown;

[0026] Figure 7 Graphs showing linear sweep voltammetry (LSV) curves of ORR of the composite materials prepared in Examples 1, 2, and 3 under 0.1 M KOH conditions.

[0027] Figure 8 The linear sweep voltammetry (LSV) curves of the OER of the composite materials prepared in Example 1, Example 4 and Example 5 under 1 M KOH conditions are shown;

[0028] Figure 9 Graphs showing linear sweep voltammetry (LSV) curves of ORR of the composite materials prepared in Example 1, Example 4, and Example 5 under 0.1 M KOH conditions. DETAILED DESCRIPTION

[0029] The above and other technical features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials and a preparation method thereof, comprising the following steps:

[0032] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0033] (2) Slowly add 200 mg of iron phthalocyanine powder into the dispersion and sonicate for 1 hour.

[0034] (3) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0035] (4) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which was recorded as FePc-LDH.

[0036] Example 2

[0037] A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials and a preparation method thereof, comprising the following steps:

[0038] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0039] (2) Slowly add 2 mg of iron phthalocyanine powder into the dispersion and sonicate for 1 h.

[0040] (3) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0041] (4) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which was recorded as FePc-LDH-2.

[0042] Example 3

[0043] A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials and a preparation method thereof, comprising the following steps:

[0044] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0045] (2) Slowly add 20 mg of iron phthalocyanine powder into the dispersion and sonicate for 1 h.

[0046] (3) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0047] (4) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which was recorded as FePc-LDH-3.

[0048] Example 4

[0049] A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials and a preparation method thereof, comprising the following steps:

[0050] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0051] (2) Slowly add 200 mg of iron phthalocyanine powder into the dispersion and sonicate for 0.5 h.

[0052] (3) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0053] (4) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which was recorded as FePc-LDH-0.5h.

[0054] Example 5

[0055] A bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials and a preparation method thereof, comprising the following steps:

[0056] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0057] (2) Slowly add 200 mg of iron phthalocyanine powder into the dispersion and sonicate for 6 h.

[0058] (3) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0059] (4) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, which was recorded as FePc-LDH-6h.

[0060] Comparative Example 1

[0061] A cobalt nickel hydroxide layered material catalyst and a preparation method thereof, comprising the following steps:

[0062] (1) Disperse 3 mmol of cobalt nitrate and 2 mmol of nickel nitrate evenly in 10 mL of anhydrous ethanol.

[0063] (2) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0064] (3) The resulting mixed solution was sonicated for 1 h, washed, centrifuged, and dried to obtain a bifunctional catalyst based on cobalt nickel hydroxide layered material, which was recorded as CoNi-LDH.

[0065] Comparative Example 2

[0066] A catalyst based on iron phthalocyanine and a preparation method thereof, comprising the following steps:

[0067] (1) Disperse 200 mg of iron phthalocyanine powder evenly in 10 mL of anhydrous ethanol.

[0068] (2) The dispersion obtained by ultrasound was quickly injected into 20 mL of 1 M KOH, injecting 50 μL each time until it was completely injected.

[0069] (3) The resulting mixed solution was sonicated for 1 h, and after the sonication, it was washed, centrifuged, and dried to obtain a bifunctional catalyst based on iron phthalocyanine material, which was recorded as FePc.

[0070] Taking the FePc-LDH composite material in Example 1 as an example, Figure 1It can be seen from the TEM that the material presents a uniform composite lamellar structure with a lamellar size of about 100 to 200 nm.

[0071] The FePc-LDH prepared in Example 1 and the CoNi-LDH prepared in Comparative Example 1 were subjected to X-ray diffraction test. Figure 2 It can be seen that the prepared FePc-LDH and CoNi-LDH have a good correspondence with the cobalt and nickel hydroxides No.16-1896 and No.08-8940 in the PDF standard card.

[0072] The prepared FePc-LDH in Example 1, CoNi-LDH in Comparative Example 1 and FePc in Comparative Example 2 were tested by Fourier transform infrared spectroscopy. Figure 3 As shown, 751cm -1 Peak representing Fe-N bonding, 1000-1450 cm -1 The peaks representing organic functional groups can all reflect the material composite of FePc and CoNi-LDH.

[0073] Figure 4 The LSV curves of FePc-LDH, CoNi-LDH and FePc prepared in 1M KOH solution are shown in the OER test diagram. In the OER test diagram, it is found that the sample FePc-LDH after the composite of iron phthalocyanine and cobalt nickel layered double metal hydroxide shows the improvement of synergistic catalytic performance, and the OER overpotential E 10 It is 270mV, which is the greatest performance advantage over commercial ruthenium oxide among the three groups of materials, indicating that the OER electrochemical performance of the composite materials has been significantly improved.

[0074] Figure 5 The LSV curves ORR diagrams of the prepared FePc-LDH, CoNi-LDH and FePc in 0.1M KOH solution, saturated O2, and 1600rpm. In the ORR test diagram, it was found that the sample FePc-LDH after the composite of iron phthalocyanine and cobalt nickel layered double hydroxide showed an improvement in synergistic catalytic performance, and the ORR half-wave potential E 1 / 2 The FePc-LDH composite material also has the largest onset potential (0.91 V) and limiting diffusion current density (6 mA cm-3) among the three groups of materials. -2 ), indicating that the ORR electrochemical performance of the composite material has been significantly improved.

[0075] Figure 6Figure 3 shows the LSV OER curves of the prepared FePc-LDH, FePc-LDH-2, and FePc-LDH-3 in 1M KOH solution. The OER test plots reveal that the OER overpotential of the FePc-LDH sample, a composite of iron phthalocyanine and cobalt-nickel layered double hydroxide, decreases with increasing FePc content, indicating that the amount of FePc incorporated enhances the OER electrochemical performance of the composite.

[0076] Figure 7 Figure 3 shows the LSV curves (ORR) of the prepared FePc-LDH, FePc-LDH-2, and FePc-LDH-3 in 0.1M KOH solution, saturated O₂, and a rotation speed of 1600 rpm. The ORR test graphs show that the ORR catalytic activity of the FePc-LDH sample, which is a composite of iron phthalocyanine and cobalt-nickel layered double hydroxide, does not change with the amount of FePc introduced, indicating that the amount of FePc introduced has no significant effect on the ORR electrochemical performance of the composite material.

[0077] Figure 8 Figure 3 shows the LSV OER curves of the prepared FePc-LDH, FePc-LDH-0.5h, and FePc-LDH-6h in 1M KOH solution. The OER test graph shows that the OER catalytic activity of the FePc-LDH sample, which is a composite of iron phthalocyanine and cobalt-nickel layered double hydroxide, does not change significantly with the duration of ultrasound, indicating that varying the duration of ultrasound has no significant effect on the OER electrochemical performance of the composite material.

[0078] Figure 9 Figure 3 shows the LSV curves for the ORR of FePc-LDH, FePc-LDH-0.5h, and FePc-LDH-6h in 0.1M KOH solution, saturated O₂, and a rotation speed of 1600 rpm. The ORR test plots reveal that the ORR catalytic activity of FePc-LDH, a composite of iron phthalocyanine and cobalt-nickel layered double hydroxide, changes significantly with sonication duration, initially increasing and then decreasing. Overall, a 1-hour sonication period appears to be ideal.

[0079] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered materials, characterized in that: The following steps are involved: S1, uniformly dispersing cobalt salt and nickel salt in an organic solvent to obtain a dispersion; S2, slowly adding iron phthalocyanine powder to the dispersion in step S1, and sonicating for 0.1 to 60 hours; S3, quickly injecting the dispersion obtained after ultrasonication in step S2 into the strong alkaline solution, injecting 100-1000 μL each time until the dispersion is completely injected to obtain a mixed solution; S4, sonicating the mixed solution obtained in step S3 for 0.1 to 80 hours, washing, centrifuging, and drying after the sonication to obtain a bifunctional catalyst composed of iron phthalocyanine and cobalt nickel hydroxide layered material, recorded as FePc-LDH; In step S1, the molar ratio of cobalt salt to nickel salt is 3:2; In step S2, the dispersion amount of iron phthalocyanine is 2-200 mg / mL.

2. The method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material according to claim 1, characterized in that: In step S1, the cobalt salt is any one of cobalt chloride, cobalt nitrate, and cobalt sulfate, or a mixture of two or more thereof; the nickel salt is any one of nickel chloride, nickel nitrate, and nickel sulfate, or a mixture of two or more thereof; and the organic solvent is any one of methanol, ethanol, and N,N-dimethylformamide, or a mixture of two or more thereof.

3. The method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material according to claim 1, characterized in that: In step S3, the strong alkaline solution is any one of lithium hydroxide, sodium hydroxide, and potassium hydroxide, or a mixture of two or more thereof.

4. The method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material according to claim 1, characterized in that: In step S3, the molar concentration of the strong base solution is 0.1-10 mol / L.

5. The method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material according to claim 1, characterized in that: In step S4, the solvent used for washing is any one of acetone, ethanol, and deionized water, or a mixture of two or more thereof.

6. The method for preparing a bifunctional catalyst composited with iron phthalocyanine and cobalt nickel hydroxide layered material according to claim 1, characterized in that: In step S4, the drying method is any one of ordinary air oven drying, vacuum drying, freeze drying, or a combination of two or more thereof, and the drying time is 1 to 144 hours.

7. A bifunctional catalyst composed of a composite of iron phthalocyanine and a cobalt nickel hydroxide layered material, prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the bifunctional catalyst of the composite of iron phthalocyanine and cobalt nickel hydroxide layered material as claimed in claim 7 in zinc-air batteries.

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