Preparation method and application of phthalocyanine iron and sulfur-doped porous carbon composite catalyst

Abstract

The application provides a preparation method of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, and comprises the following steps: S1, sulfur-doped porous carbon material preparation: firstly, uniformly mix coal pitch, KOH and nano ZnO through a ball milling process, and carbonize the mixture in a nitrogen atmosphere; then, immerse the carbonized sample in dilute hydrochloric acid, clean and dry the sample after removing the nano ZnO, and obtain the sulfur-doped porous carbon material; S2, phthalocyanine iron and sulfur-doped porous carbon composite: add the sulfur-doped porous carbon material and phthalocyanine iron into a DMF solution, magnetically stir the sample, clean and dry the sample, and obtain the phthalocyanine iron and sulfur-doped porous carbon composite catalyst. The composite catalyst prepared by the application has excellent ORR catalytic performance and stability, and when the composite catalyst is applied to a zinc air battery, the battery has good charge-discharge performance and cycle stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical energy storage materials, more particularly to a preparation method of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst and application thereof. BACKGROUND

[0002] As a new type of green and environmentally friendly energy storage device, rechargeable zinc-air battery (referred to as "zinc-air battery") has developed rapidly in recent years. Zinc-air battery is an electrochemical battery with air electrode as the positive electrode and metal zinc electrode as the negative electrode. During discharging, oxygen reduction reaction (ORR) occurs at the air electrode; during charging, oxygen evolution reaction (OER) occurs at the air electrode. Because the active substance (oxygen) does not occupy the internal space of the battery, the zinc-air battery has a higher theoretical energy density (1218 Wh / kg and 6136 Wh / L) than the traditional closed battery, which can meet the needs of large-scale applications. Therefore, zinc-air battery is expected to have a brilliant future in large-scale power grid energy storage, electric vehicles, wearable electronic products and other fields.

[0003] However, the air positive electrode of zinc-air battery needs to undergo four-electron ORR / OER reaction during charging and discharging, which causes slow battery dynamics. In addition, due to the lack of excellent dual-function ORR / OER catalyst, the energy efficiency of zinc-air battery is relatively low. Therefore, it is necessary to construct high-performance ORR / OER dual-function catalyst to participate in the above process. At present, noble metal catalysts (such as platinum, iridium, ruthenium, etc.) exhibit relatively excellent oxygen electrocatalytic performance, but the low reserves, high price, insufficient dual-functionality and easy poisoning of noble metal catalysts seriously restrict their application in this field. Non-noble metal catalysts have attracted widespread attention due to their abundant reserves, low cost and adjustable advantages. Phthalocyanine iron molecular catalyst is considered to be a good oxygen catalyst. However, due to the planar structure of phthalocyanine iron itself, the catalytic activity of phthalocyanine iron is limited, and the reaction stability is reduced. Therefore, the present application designs a phthalocyanine iron composite catalyst material to improve its oxygen catalytic activity and stability, which is applied as an efficient oxygen catalyst in zinc-air battery. SUMMARY

[0004] The present application provides a preparation method of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, and the prepared composite catalyst exhibits excellent ORR catalytic performance and stability.

[0005] A preparation method of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, comprising the following steps:

[0006] S1. Preparing sulfur-doped porous carbon material: firstly, mix coal pitch, KOH and nano-ZnO uniformly through a ball milling process, and carbonize the mixture in a nitrogen atmosphere; then, immerse the carbonized sample in dilute hydrochloric acid, clean and dry the sample after removing the nano-ZnO, and obtain the sulfur-doped porous carbon material;

[0007] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: add the sulfur-doped porous carbon material and phthalocyanine iron into a DMF solution, clean and dry the sample after magnetic stirring, and obtain the phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0008] Preferably, in the step S1, the mixing ratio of coal pitch, KOH and nano-ZnO is 1:3-5:5-8.

[0009] Preferably, in the step S1, the carbonization temperature is 600-900℃, and the carbonization time is 1-2h.

[0010] Preferably, in the step S1, the concentration of dilute hydrochloric acid is 3-7mol / L, and the immersion time is 6-12h.

[0011] Preferably, in the step S1, the coal pitch is high-temperature petroleum pitch in the form of powder, the particle size is 3-5μm, the softening point is 275-285℃, and the carbon residue rate is ≥75%.

[0012] Preferably, in the step S2, the ratio of the sulfur-doped porous carbon material to phthalocyanine iron is 3-10:1.

[0013] Preferably, in the step S2, the stirring temperature is 40-80℃, and the stirring time is 7-12h.

[0014] Preferably, in the step S2, the purity of the DMF solution is 99.8%.

[0015] In the technical scheme of the present application, the sulfur-doped porous carbon material is obtained by carbonizing coal pitch, and KOH and nano-ZnO mainly play the roles of activation and pore formation in the carbonization process. Since coal pitch contains sulfur, the sulfur-doped porous carbon is obtained after carbonization. In addition, the composite of phthalocyanine iron and sulfur-doped porous carbon enables the phthalocyanine iron to be vertically grafted on the sulfur-doped porous carbon, forming a stable three-dimensional structure and eliminating the shortcomings of poor adsorption and activation ability of the FeN4 site of the planar symmetrical phthalocyanine iron. The Fe site forms Fe-S coordination through interaction with the S site of the sulfur-doped porous carbon, and the electronic localization of the S-FeN4 site axis is enhanced, thereby enhancing the adsorption and activation of O2. The structure of the composite catalyst is shown in Figure 1The composite structure breaks the symmetry of the geometric structure and electronic structure of phthalocyanine iron, optimizes the adsorption of reaction intermediates, improves the intrinsic catalytic activity of the catalytic site, and also improves the stability of the catalyst itself. Therefore, the composite catalyst exhibits good catalytic activity and stability.

[0016] The application also provides application of the phthalocyanine iron and sulfur-doped porous carbon composite catalyst in a zinc-air battery.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] (1) The structural defects of phthalocyanine iron have always been the main factor affecting its catalytic performance. In the application, when phthalocyanine iron is compounded with sulfur-doped porous carbon material, the S site is fixed to phthalocyanine iron by forming Fe-S coordination, thereby strengthening the interaction between phthalocyanine iron and sulfur-doped porous carbon, improving the planar structural defects and electronic defects of phthalocyanine iron itself, improving the intrinsic catalytic activity and stability of the composite catalyst, and enabling the composite catalyst to be applied to high-performance zinc-air batteries.

[0019] (2) The phthalocyanine iron and sulfur-doped porous carbon composite catalyst prepared in the application has a high specific surface area and good electrical conductivity, and exhibits excellent oxygen electrocatalytic performance; when the catalyst is applied to a zinc-air battery, the battery exhibits good charge-discharge performance and cycle stability.

[0020] (3) The application compounds phthalocyanine iron with sulfur-doped porous carbon material by using a simple solution method, thereby achieving the purpose of compensating for the structural defects of phthalocyanine iron, and having the advantages of simple operation, low energy consumption, good repeatability and the like.

[0021] (4) The sulfur-doped porous carbon material is obtained by one-step carbonization of coal pitch, and the preparation of the sulfur-doped porous carbon material is simpler and more efficient than the traditional preparation of sulfur-doped carbon materials. At the same time, since no additional sulfur source is needed and the synthesis raw material is inexpensive, the obtained carbon material has the advantages of low cost and batch production. In addition, by using coal pitch waste, the purpose of waste recycling can be achieved, environmental pollution can be reduced, and a new application way of coal pitch is developed. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 (a) is a structural schematic diagram of a phthalocyanine iron catalyst (FePc), Figure 1 (b) is a structural schematic diagram of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst (FePc@PDC) according to the application.

[0023] Figure 2 (a) and (b), Figure 2 (c) and (d) are scanning electron microscope (SEM) pictures of the sulfur-doped porous carbon material (PDC) and FePc@PDC of Example 1 at different magnifications, respectively.

[0024] Figure 3 X-ray diffraction (XRD) patterns of FePc@PDC of Example 1, PDC of Comparative Example 1, FePc of Comparative Example 2.

[0025] Figure 4 BET specific surface area curves of FePc@PDC of Example 1, PDC of Comparative Example 1, FePc of Comparative Example 2.

[0026] Figure 5 (a) LSV curves of ORR measured at different rotation rates for FePc@PDC of Example 1; Figure 5 (b) LSV curves of ORR measured at 1600 rpm for FePc@PDC of Example 1, PDC of Comparative Example 1, FePc of Comparative Example 2.

[0027] Figure 6 (a) and (b) are open circuit voltage, discharge curve and corresponding power density curve of zinc-air battery assembled by FePc@PDC of Example 1, respectively.

[0028] Figure 7 Cycle life curve of zinc-air battery assembled by FePc@PDC of Example 1. DETAILED DESCRIPTION

[0029] The application will be further described in conjunction with the specific embodiments, but the embodiments do not limit the application in any form. Unless otherwise specified, the raw materials used in the embodiments of the application are commercially available raw materials.

[0030] Example 1

[0031] A preparation method of a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, comprising the following steps:

[0032] S1. Preparation of sulfur-doped porous carbon material: first, 0.5 g of coal pitch (particle size of 5 μm, softening point of 278℃, and residual carbon rate of 75%), 2 g of KOH, and 3 g of nano-ZnO are uniformly mixed by a ball milling process, and the mixing ratio is 1:4:6; the mixture is carbonized by calcination in a nitrogen atmosphere, and the calcination temperature is 800℃ and the calcination time is 2 h. Then, the carbonized sample is soaked in 3 mol / L dilute hydrochloric acid for 12 h, and after removing the nano-ZnO, it is thoroughly washed with distilled water and dried at 80℃ to obtain a sulfur-doped porous carbon material;

[0033] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 40 mg of phthalocyanine iron are added to 200 mL of DMF solution with a purity of 99.8%, and the addition ratio of the two is 5:1; after magnetic stirring at a stirring temperature of 80°C and a stirring time of 12 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0034] Example 2

[0035] A method for preparing a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, comprising the following steps:

[0036] S1. Preparation of sulfur-doped porous carbon material: 0.5 g of coal pitch (particle size of 5 μm, softening point of 278°C, and carbon residue rate of 75%), 2.5 g of KOH, and 3.5 g of nano-ZnO are first mixed uniformly by a ball milling process, and the mixing ratio is 1:5:7; the mixture is carbonized by calcination in a nitrogen atmosphere, and the calcination temperature is 900°C and the calcination time is 1 h. Then, after the carbonized sample is soaked in 5 mol / L dilute hydrochloric acid for 8 h, the nano-ZnO is removed, and the sample is thoroughly cleaned with distilled water and dried at 80°C to obtain a sulfur-doped porous carbon material;

[0037] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 50 mg of phthalocyanine iron are added to 200 mL of DMF solution with a purity of 99.8%, and the addition ratio of the two is 4:1; after magnetic stirring at a stirring temperature of 60°C and a stirring time of 8 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0038] Example 3

[0039] A method for preparing a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, comprising the following steps:

[0040] S1. Preparation of sulfur-doped porous carbon material: 0.5 g of coal pitch (particle size of 5 μm, softening point of 278°C, and carbon residue rate of 75%), 2.5 g of KOH, and 3.5 g of nano-ZnO are first mixed uniformly by a ball milling process, and the mixing ratio is 1:5:7; the mixture is carbonized by calcination in a nitrogen atmosphere, and the calcination temperature is 900°C and the calcination time is 1 h. Then, after the carbonized sample is soaked in 5 mol / L dilute hydrochloric acid for 8 h, the nano-ZnO is removed, and the sample is thoroughly cleaned with distilled water and dried at 80°C to obtain a sulfur-doped porous carbon material;

[0041] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 40 mg of phthalocyanine iron are added to 200 mL of DMF solution with a purity of 99.8%, and the two are added at a ratio of 5:1; after magnetic stirring at a stirring temperature of 80°C and a stirring time of 12 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0042] Example 4

[0043] A method for preparing a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, comprising the following steps:

[0044] S1. Preparation of sulfur-doped porous carbon material: 0.5 g of coal pitch (particle size 5 μm, softening point 278°C, carbon residue rate 75%), 2 g of KOH, and 3 g of nano-ZnO are first mixed uniformly by a ball milling process, and the mixing ratio is 1:4:6; the mixture is carbonized by calcination in a nitrogen atmosphere, and the calcination temperature is 800°C and the calcination time is 2 h. Then the carbonized sample is soaked in 3 mol / L dilute hydrochloric acid for 12 h, and after removing the nano-ZnO, it is thoroughly cleaned with distilled water and dried at 80°C to obtain a sulfur-doped porous carbon material;

[0045] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 20 mg of phthalocyanine iron are added to 200 mL of DMF solution with a purity of 99.8%, and the two are added at a ratio of 10:1; after magnetic stirring at a stirring temperature of 40°C and a stirring time of 11 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0046] Comparative Example 1

[0047] The sulfur-doped porous carbon material prepared in step S1 of Example 1 is used.

[0048] Comparative Example 2

[0049] A method for preparing a phthalocyanine iron catalyst: commercial phthalocyanine iron is added to 200 mL of DMF solution with a purity of 99.8%, and after magnetic stirring at a stirring temperature of 80°C and a stirring time of 12 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron catalyst.

[0050] Comparative Example 3

[0051] A method for preparing a phthalocyanine iron and carbon composite material: 200 mg of acetylene black and 40 mg of phthalocyanine iron are added to 200 mL of DMF solution with a purity of 99.8%, and the two are added at a ratio of 5:1; after magnetic stirring at a stirring temperature of 80°C and a stirring time of 12 h, the sample is cleaned and dried at 80°C to obtain a phthalocyanine iron and carbon composite material.

[0052] Comparative Example 4

[0053] A method for preparing a composite material of phthalocyanine iron and sulfur-doped carbon includes the following steps:

[0054] S1. Preparation of sulfur-doped carbon material: First, 0.5 g of coal tar pitch (particle size 5 μm, softening point 278℃, carbon residue 75%) was ground by ball milling. The obtained coal tar pitch powder was then calcined and carbonized in a nitrogen atmosphere at 800℃ for 2 h. The carbonized sample was then soaked in 3 mol / L dilute hydrochloric acid for 12 h, and finally thoroughly washed with distilled water and dried at 80℃ to obtain the sulfur-doped carbon material.

[0055] S2. Phthalocyanine iron and sulfur-doped carbon composite: 200 mg of sulfur-doped carbon and 40 mg of phthalocyanine iron were added to 200 mL of DMF solution with a purity of 99.8% at a ratio of 5:1. After magnetic stirring at 80 °C for 12 h, the sample was cleaned and dried at 80 °C to obtain the phthalocyanine iron and sulfur-doped carbon composite material.

[0056] Comparative Example 5

[0057] A method for preparing a composite catalyst of phthalocyanine iron and sulfur-doped porous carbon includes the following steps:

[0058] S1. Preparation of sulfur-doped porous carbon material: First, 0.5g of coal tar pitch (particle size 5μm, softening point 278℃, char residue 75%), 1g of KOH, and 2g of nano-ZnO were mixed evenly by ball milling at a ratio of 1:2:4. The mixture was then calcined in a nitrogen atmosphere at 500℃ for 3h. The carbonized sample was then soaked in 3mol / L dilute hydrochloric acid for 12h to remove the nano-ZnO, thoroughly washed with distilled water, and dried at 80℃ to obtain the sulfur-doped porous carbon material.

[0059] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 40 mg of phthalocyanine iron were added to 200 mL of DMF solution with a purity of 99.8% at a ratio of 5:1. After magnetic stirring at 80 °C for 12 h, the sample was cleaned and dried at 80 °C to obtain the phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0060] Comparative Example 6

[0061] A method for preparing a composite catalyst of phthalocyanine iron and sulfur-doped porous carbon includes the following steps:

[0062] S1. Preparation of sulfur-doped porous carbon material: First, 0.5g of coal tar pitch (particle size 5μm, softening point 278℃, char residue 75%), 2g of KOH, and 3g of nano-ZnO were mixed evenly by ball milling in a ratio of 1:4:6. The mixture was then calcined in a nitrogen atmosphere at 800℃ for 2 hours. The carbonized sample was then soaked in 3mol / L dilute hydrochloric acid for 12 hours to remove the nano-ZnO, thoroughly washed with distilled water, and dried at 80℃ to obtain the sulfur-doped porous carbon material.

[0063] S2. Phthalocyanine iron and sulfur-doped porous carbon composite: 200 mg of sulfur-doped porous carbon material and 100 mg of phthalocyanine iron were added to 200 mL of DMF solution with a purity of 99.8% at a ratio of 2:1. After magnetic stirring at 90 °C for 6 h, the sample was cleaned and dried at 80 °C to obtain the phthalocyanine iron and sulfur-doped porous carbon composite catalyst.

[0064] The test results of the materials prepared in Examples 1-4 and Comparative Examples 1-6 are shown in the table below:

[0065]

[0066] In addition, the performance test results for FePc@PDC of Example 1, PDC of Comparative Example 1, and FePc of Comparative Example 2 are as follows: Figures 2 to 7 As shown.

[0067] Figure 2 In Figures (a) and (b), it can be observed that the PDC synthesized in Example 1 is a carbon material with a rich porous structure. Figures (c) and (d) show that in the prepared FePc@PDC, phthalocyanine iron molecules are uniformly dispersed on the sulfur-doped porous carbon material, forming a uniform composite material. Furthermore, the porosity of FePc@PDC is reduced compared to PDC. This is because the porosity of FePc is relatively smaller than that of PDC, resulting in a lower porosity and fewer pores in the composite material.

[0068] Figure 3 In the comparison, it can be seen that the PDC of Comparative Example 1 shows the diffraction peak of carbon (JCPDS#75-2078) on the (111) crystal plane, and the FePc of Comparative Example 2 shows the diffraction peak corresponding to iron phthalocyanine. The simultaneous appearance of diffraction peaks of carbon and iron phthalocyanine in the FePc@PDC of Example 1 indicates the successful synthesis of the composite catalyst.

[0069] Figure 4 As can be seen from the data, the PDC in Comparative Example 1 has the largest specific surface area, which is 1375.69 m². 2 / g; The specific surface area of ​​FePc@PDC in Example 1 is slightly smaller than that of PDC, at 1017.57m².2 / g, the specific surface area of ​​both is consistent with the SEM results. However, the specific surface area of ​​FePc in Comparative Example 2 is 15.91m². 2 The specific surface area is much smaller than that of PDC and FePc@PDC, indicating that the presence of porous structure after the composite of phthalocyanine iron and sulfur-doped porous carbon materials significantly increases the specific surface area, which is beneficial to exposing more active sites to participate in catalytic reactions and enhance the catalytic performance of the composite catalyst.

[0070] Figure 5 As shown in (a), the limiting current density of FePc@PDC in Example 1 increases steadily with the increase of the test rotation speed; when the rotation speed reaches the maximum, the limiting current reaches the maximum. Figure 5 As shown in (b), under 1600 rpm conditions, compared with PDC in Comparative Example 1, FePc in Comparative Example 2, and the noble metal Pt / C catalyst, the half-wave potential of the FePc@PDC composite catalyst in Example 1 is significantly higher than that of PDC and FePc, and close to that of the Pt / C catalyst, indicating that the FePc@PDC composite catalyst has good ORR catalytic performance.

[0071] Figure 6 In (a), it can be seen that the zinc-air battery assembled with FePc@PDC in Example 1 has a high open-circuit voltage, reaching 1.56V; Figure 6 (b) It can also be seen that the maximum current of the zinc-air battery can reach 165 mA cm during discharge. -2 Meanwhile, the peak power density also reached 74 mW cm⁻¹. -2 .

[0072] Figure 7 As can be seen from the data, the zinc-air battery assembled with FePc@PDC in Example 1 exhibits a high discharge voltage and a low charging voltage, indicating good charge-discharge efficiency. Furthermore, the battery's charge-discharge performance remains unchanged after 17 hours of stable cycling, demonstrating excellent charge-discharge performance and stable cycle life.

[0073] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a phthalocyanine iron and sulfur-doped porous carbon composite catalyst, characterized by comprising the following steps: The method comprises the following steps: ​ S1. Preparing sulfur-doped porous carbon material: firstly, uniformly mixing coal pitch, KOH and nano-ZnO through a ball milling process, and carbonizing the mixture in a nitrogen atmosphere; then, immersing the carbonized sample in dilute hydrochloric acid, thoroughly cleaning and drying the sample after removing the nano-ZnO, and obtaining the sulfur-doped porous carbon material; S2. Compounding phthalocyanine iron and sulfur-doped porous carbon: adding the sulfur-doped porous carbon material and phthalocyanine iron into a DMF solution, magnetically stirring the sample, cleaning and drying the sample, and obtaining the phthalocyanine iron and sulfur-doped porous carbon composite catalyst; In the step S1, the mixing ratio of the coal pitch, KOH and nano-ZnO is 1:3-5:5-8; the calcination temperature is 600-900℃, and the calcination time is 1-2 h; the coal pitch is high-temperature petroleum pitch in the form of powder, the particle size is 3-5 μm, the softening point is 275-285℃, and the carbon residue rate is ≥75 %; In the step S2, the ratio of the sulfur-doped porous carbon material to the phthalocyanine iron is 3-10:1; the stirring temperature is 40-80℃, and the stirring time is 7-12 h.

2. The production method according to claim 1, wherein In the step S1, the concentration of the dilute hydrochloric acid is 3-7 mol / L, and the immersion time is 6-12 h.

3. The production method according to claim 1, wherein In the step S2, the purity of the DMF solution is 99.8 %.

4. A phthalocyanine iron and sulfur-doped porous carbon composite catalyst, which is prepared by the preparation method of any one of claims 1-3.

5. Application of the composite catalyst of claim 4 in a zinc-air battery.

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