A method for preparing, producing, and applying an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst.

Abstract

This invention discloses a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst, the product, and its application. ZIF-67 and carbon black are mixed and pyrolyzed at high temperature to obtain the precursor ZIF-67 / C-T. The catalyst is then prepared by mixing the ionic liquid [Bmim]3[Fe(CN)6] and ZIF-67 / C-T and pyrolyzing at high temperature. The mass ratio of ZIF-67 to carbon black is 1:0.5–2.5, and the volume-to-mass ratio of the ionic liquid to ZIF-67 / C-T is 1:5–25. The pyrolysis temperature is 400–800℃, the pyrolysis time is 2 hours, and the pyrolysis atmosphere is nitrogen. This invention provides a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst, which combines ZIF-67, the ionic liquid ([Bmim]3[Fe(CN)6), and carbon black to achieve a good synergistic catalytic effect. Furthermore, by optimizing the compounding ratio, the oxygen reduction performance is optimized.

Description

Technical Field

[0001] This invention belongs to the field of oxygen reduction catalysis, specifically relating to a method for preparing an iron-based ionic liquid-controlled metal-organic framework ZIF-67 catalyst, as well as its product and application. Background Technology

[0002] In recent years, with the rapid development of human economy and society and the large-scale industrial production, the demand for energy has increased dramatically. Currently, traditional fossil fuels, such as coal, oil, and natural gas, remain the main sources of energy consumption, accounting for over 80% of the market. However, these non-renewable fossil fuels are slowly formed and have limited reserves; predatory extraction will only lead to a more severe energy crisis. With societal development, the energy crisis problem has become increasingly prominent. Furthermore, the direct combustion of fossil fuels produces CO2, SO2, and NO. x Harmful gases. To address the dual pressures of energy scarcity and environmental pollution, and to achieve the global goal of green, economical, and sustainable development, researchers are dedicated to developing new energy sources and advancing energy conversion technologies.

[0003] Establishing an electrochemical energy conversion system centered on hydrogen, oxygen, and water is a promising development direction. Several important energy conversion technologies can be derived from this system, such as hydrogen production through water electrolysis, fuel cells, and metal-air batteries. Among these, hydrogen energy boasts advantages such as high energy density, high calorific value, zero carbon dioxide emissions, and recyclability, making it a promising future fuel. Metal-air batteries, with their high energy density, good safety, and environmental friendliness, have also attracted considerable attention as a novel energy conversion technology, with a very broad commercial prospect.

[0004] Currently, commercially available ORR catalysts are mainly platinum-based noble metals. Although they exhibit high catalytic activity, they generally suffer from problems such as limited catalytic function, scarcity of resources, high price, and poor toxicity resistance. Therefore, the search for efficient alternative catalysts is urgent. Thanks to the unremitting efforts of researchers, various efficient, inexpensive, and stable ORR catalysts have been reported, mainly including transition metals and their alloys, metal compounds, and non-metallic materials. Carbon-based materials are an abundant Earth resource, possessing advantages such as environmental friendliness and tunable structure and morphology, making them highly favored by researchers as substrates or precursors for ORR catalysts. However, currently, the catalytic performance of carbon-based materials is relatively poor, and their processing is quite complex. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst, comprising,

[0009] ZIF-67 / C was prepared by mixing ZIF-67 and carbon black, and the precursor ZIF-67 / CT was prepared by high-temperature pyrolysis.

[0010] The mass ratio of ZIF-67 to carbon black is 1:0.5 to 2.5, the heating rate is 2 to 5℃ / min, and the calcination temperature is 400 to 800℃.

[0011] ZIF-67 / CT-Fe(IL) was prepared by mixing ionic liquid [Bmim]3[Fe(CN)6] and ZIF-67 / CT and calcining at high temperature.

[0012] The volume-to-mass ratio of the ionic liquid to ZIF-67 / CT is 1:5 to 25.

[0013] ZIF-67 / C-600-Fe(IL) was calcined at high temperature to obtain ZIF-67 / CT-Fe(IL)-T;

[0014] The heating rate is 2–5℃ / min, and the calcination temperature is 400–800℃.

[0015] In a preferred embodiment of the preparation method described in this invention, the ZIF-67 and carbon black are mixed in a ratio of 1:1.5.

[0016] In a preferred embodiment of the preparation method described in this invention, the calcination temperature of ZIF-67 / C is 600℃.

[0017] In a preferred embodiment of the preparation method described in this invention, the calcination heating rate of ZIF-67 / C is 4℃ / min.

[0018] In a preferred embodiment of the preparation method described in this invention, the mixing ratio of [Bmim]3[Fe(CN)6] and ZIF-67 / CT is 1:15.

[0019] In a preferred embodiment of the preparation method described in this invention, the calcination temperature of ZIF-67 / CT-Fe(IL) is 600℃.

[0020] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a product of an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst.

[0021] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an iron-based ionic liquid-controlled metal-organic framework ZIF-67 catalyst, and to use the product obtained as an oxygen reduction catalyst.

[0022] Beneficial effects of this invention:

[0023] (1) This invention provides a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst. The method involves high-temperature pyrolysis of ZIF-67 / C and carbon black, followed by pyrolysis with an ionic liquid ([Bmim]3[Fe(CN)6]) to prepare a highly efficient oxygen reduction catalyst. The catalyst synthesis process is simple and easy to repeat. At the same time, the prepared catalyst particles are not prone to agglomeration, which improves the oxygen reduction performance of the catalyst.

[0024] (2) This invention provides a method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst, which combines ZIF-67 / C, ionic liquid ([Bmim]3[Fe(CN)6]) and carbon black to achieve a good synergistic catalytic effect; at the same time, by optimizing the ratio of the three components, the oxygen reduction performance is optimized. Attached Figure Description

[0025] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 The images show the XRD patterns of the catalysts used in Examples 2, 3, and 6 of this invention.

[0027] Figure 2 The LSV diagrams for samples with different carbon black content in this embodiment of the invention are shown at 1600 rpm.

[0028] Figure 3 The LSV diagrams for samples with different amounts of ionic liquid added in this embodiment of the invention are shown at 1600 rpm.

[0029] Figure 4 The LSV diagrams of samples calcined at different temperatures at 1600 rpm are shown in the embodiments of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Oxygen reduction reaction performance evaluation in the embodiments of the present invention:

[0034] Tests were conducted using an electrochemical workstation.

[0035] First, polish the glassy carbon electrode (with an area of ​​0.1256 cm²) with a small amount of 1μm aluminum oxide polishing powder. 2 The surface was polished until glossy, then rinsed with deionized water and ethanol, and air-dried at room temperature. 2 mg of catalyst and 2 mg of activated carbon were weighed and placed in a sample tube, along with 1 mL of anhydrous ethanol and 50 μL of Nafion solution. After sonication, a uniformly dispersed ink was obtained. 15.8 μL of this ink was then dropped onto the glassy carbon electrode surface and air-dried at room temperature for later use. The catalyst loading on the electrode surface was 0.24 mg / cm³. -2 ;

[0036] The electrochemical performance of the catalyst at room temperature was tested in a three-electrode system. A glassy carbon electrode (GC) with the catalyst supported was used as the working electrode, a KCl-saturated Ag / AgCl electrode was used as the reference electrode, and a carbon rod was used as the counter electrode.

[0037] The voltage range of the CV test curve is 0.2 to -1V, and the sweep rate is 50mV / s.

[0038] The RDE rotation speed for LSV testing is 400-2500 rpm, the test voltage range is 0.2 to -1V, and the scan speed is 5mV / s.

[0039] The polarization curves provide three important parameters for the performance of ORR catalysts: onset potential, half-wave potential, and limiting current density.

[0040] The more positive the onset potential and half-wave potential, and the greater the limiting current density, the higher the electrocatalytic oxygen reduction activity of the catalyst.

[0041] E 1 / 2 The potential value corresponding to half of the ORR limiting diffusion current in the LSV diagram at 1600 rpm.

[0042] The raw materials used in the embodiments of this invention are all commercially available products.

[0043] Example 1

[0044] Preparation and testing of ZIF-67 material:

[0045] (1) Weigh 8g of 2-methylimidazole and place it in a beaker. Pour 50mL of methanol into the beaker and stir evenly with a magnetic stirrer to obtain white solution A.

[0046] Weigh 2g of Co(NO3)2·6H2O and place it in a beaker. Pour 100mL of methanol into the beaker and stir evenly with a magnetic stirrer to obtain a dark red transparent solution B.

[0047] Place solution B into a constant pressure funnel and pump at a rate of 1 ml / min. -1 The solution was slowly added dropwise to solution A while the solution was stirred for 12 hours to obtain a purple solution C.

[0048] Then, centrifuge solution C and repeat the above steps until the supernatant is colorless. Collect the purple precipitate and dry it in an oven at 60°C overnight.

[0049] The obtained purple product was ground evenly in an agate mortar, and the resulting purple powder was ZIF-67.

[0050] (2) Preparation of ZIF-67 / C material:

[0051] Weigh 8g of 2-methylimidazole and xg (x=0.4,0.6,1,1.4,1.8) of carbon black into a beaker, pour 50mL of methanol into the beaker, and stir evenly with a magnetic stirrer to obtain black solution D;

[0052] Weigh 2g of Co(NO3)2·6H2O and place it in a beaker. Pour 100mL of methanol into the beaker and stir with a magnetic stirrer to obtain a dark red transparent solution E.

[0053] Place solution E into a constant pressure funnel and pump at a rate of 1 ml / min. -1 The solution was slowly added dropwise to solution D while the solution was stirred for 12 hours to obtain a black solution F.

[0054] Then, centrifuge solution F and repeat the above steps until the supernatant is colorless. Collect the black precipitate and dry it in an oven at 60°C overnight.

[0055] The obtained black product is ground evenly in an agate mortar, and the resulting black powder is ZIF-67 / C.

[0056] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 2 ;

[0057] It can be seen that the ZIF-67 / C (1:1.5) catalyst has the highest electrocatalytic oxygen reduction performance, with a half-wave potential of 0.73V vs RHE.

[0058] Example 2

[0059] (1) Preparation of [Bmim]BF4 material:

[0060] [Bmim]BF4 was purchased from Beijing Innocare Technology Co., Ltd., with a purity of 99%.

[0061] 6.1 g of [Bmim]BF4 and 0.58 g of K3[Fe(CN)6] were dissolved in 200 mL of acetonitrile. After stirring at room temperature, the mixture was filtered to obtain a solid. After drying, the solid was dispersed in deionized water and stirred for 24 hours before being freeze-dried. The resulting yellow-green powder was designated as [Bmim]3[Fe(CN)6].

[0062] (2) Preparation of ZIF-67 / CT-Fe(IL) material:

[0063] 1 mg of [Bmim]3[Fe(CN)6] and y mg (y = 5, 10, 15, 20, 25) of ZIF-67 / CT were loaded into a sample tube containing 10 ml of anhydrous ethanol. The sample tube was sonicated for 1 hour. The mixed solution was then dried in an oven at 60 °C for 12 hours to obtain the ZIF-67 / CT-Fe(IL) catalyst.

[0064] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 3 ;

[0065] It can be seen that the ZIF-67 / C-600-Fe(IL)(15:1) catalyst has the highest electrocatalytic oxygen reduction performance, with an electrocatalytic oxygen reduction half-wave potential of 0.88V vs RHE.

[0066] Example 3

[0067] (1) Preparation of ZIF-67 / CT-Fe(IL)-T material:

[0068] A certain amount of ZIF-67 / C-Fe(IL)(15:1) was placed in a tube furnace for calcination at a heating rate of 4℃ / min and a calcination temperature of 400℃ to obtain the ZIF-67 / C-Fe(IL)(15:1)-400 catalyst.

[0069] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 4 The half-wave potential of ZIF-67 / C-Fe(IL)(15:1)-400 electrocatalytic oxygen reduction is 0.82V vs RHE.

[0070] Example 4

[0071] Preparation and testing of ZIF-67 / C-600-Fe(IL)(15:1)-500 catalyst calcined at 500℃:

[0072] Same as Example 3, using the same synthesis method, the calcination temperature of ZIF-67 / C-600-Fe(IL)(15:1) was 500℃, and all other conditions remained unchanged. The final product was named ZIF-67 / C-600-Fe(IL)(15:1)-500.

[0073] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 4 The half-wave potential of ZIF-67 / C-600-Fe(IL)(15:1)-500 electrocatalytic oxygen reduction is 0.86Vvs RHE.

[0074] Example 5

[0075] Preparation and testing of ZIF-67 / C-600-Fe(IL)(15:1)-600 catalyst calcined at 600℃:

[0076] Similar to Example 3, the same synthesis method was used, and the calcination temperature of ZIF-67 / C-600-Fe(IL)(15:1) was 600℃, while all other parameters remained unchanged. The final product was named ZIF-67 / C-600-Fe(IL)(15:1)-600.

[0077] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 4 ;

[0078] It can be seen that the ZIF-67 / C-600-Fe(IL)(15:1)-600 catalyst has the highest electrocatalytic oxygen reduction performance, with an electrocatalytic oxygen reduction half-wave potential of 0.90V vs RHE.

[0079] Example 6

[0080] Preparation and testing of ZIF-67 / C-600-Fe(IL)(15:1)-700 catalyst calcined at 700℃:

[0081] Same as Example 3, using the same synthesis method, the calcination temperature of ZIF-67 / C-600-Fe(IL)(15:1) was 700℃, and all other conditions remained unchanged. The final product was named ZIF-67 / C-600-Fe(IL)(15:1)-700.

[0082] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 4 The half-wave potential of ZIF-67 / C-600-Fe(IL)(15:1)-700 electrocatalytic oxygen reduction is 0.86Vvs RHE.

[0083] Example 7

[0084] Preparation and testing of ZIF-67 / C-600-Fe(IL)(15:1)-800 catalyst calcined at 800℃:

[0085] Same as Example 3, using the same synthesis method, the calcination temperature of ZIF-67 / C-600-Fe(IL)(15:1) was 800℃, and all other conditions remained unchanged. The final product was named ZIF-67 / C-600-Fe(IL)(15:1)-800.

[0086] After preparing the above catalyst into a working electrode and performing electrocatalytic oxygen reduction tests, see [link to relevant documentation]. Figure 4 The half-wave potential of ZIF-67 / C-600-Fe(IL)(15:1)-800 electrocatalytic oxygen reduction is 0.83Vvs RHE.

[0087] The XRD patterns of ZIF-67 / C-600-Fe(IL)(15:1) and ZIF-67 / C-600-Fe(IL)(15:1)-T prepared in Examples 2, 3, and 6 of this invention are shown in the figure. Figure 1The optimal mass ratio of ZIF-67 to carbon black is 1:1.5, the mass ratio of ZIF-67 / C-600 to [Bmim]3[Fe(CN)6] is 15:1, the calcination temperature is 600℃, and the heating rate is 4℃ / min to achieve the best oxygen reduction catalytic effect.

[0088] This invention prepares a highly efficient oxygen reduction catalyst by high-temperature pyrolysis of a mixture of ZIF-67 and carbon black, followed by pyrolysis of a mixture of ZIF-67 / CT and ionic liquid ([Bmim]3[Fe(CN)6]). The catalyst synthesis process is simple and reproducible; the prepared catalyst particles are not prone to agglomeration and exhibit high oxygen reduction catalytic activity and conductivity.

[0089] This invention combines ZIF-67, ionic liquid ([Bmim]3[Fe(CN)6]) and carbon black to achieve a good synergistic catalytic effect; at the same time, by optimizing the compounding ratio, the oxygen reduction performance is optimized.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing an iron-based ionic liquid-regulated metal-organic framework ZIF-67 catalyst, characterized in that: include, ZIF-67 / C was prepared by mixing ZIF-67 and carbon black, and the precursor ZIF-67 / CT was prepared by high-temperature pyrolysis. ZIF-67 / CT-Fe(IL) was prepared by mixing ionic liquid [Bmim]3[Fe(CN)6] with ZIF-67 / CT. ZIF-67 / C-600-Fe(IL) was calcined at high temperature to obtain ZIF-67 / CT-Fe(IL)-T; The mass ratio of ZIF-67 to carbon black is 1:0.5 to 2.5, and the volume mass ratio of ionic liquid to ZIF-67 / CT is 1:5 to 25.

2. The preparation method according to claim 1, characterized in that: The high-temperature pyrolysis temperature is 400–800℃, the pyrolysis time is 2 hours, and the pyrolysis atmosphere is nitrogen.

3. The preparation method according to claim 1 or 2, characterized in that: The ZIF-67 / C is prepared by a method comprising, 2-Methylimidazole and carbon black were dissolved in anhydrous methanol and stirred until homogeneous to obtain black solution A; Cobalt nitrate was dissolved in anhydrous methanol and stirred until homogeneous to obtain a deep red transparent solution B; Slowly add solution B to solution A and continue stirring for 6–12 hours; Then, the product is washed by centrifugation with methanol until the supernatant is colorless. The product is then dried at 60-80℃ for 10-12 hours to obtain ZIF-67 / C.

4. The preparation method according to claim 1 or 2, characterized in that: The preparation method of the ionic liquid [Bmim]3[Fe(CN)6] includes, [Bmim]BF4 and K3[Fe(CN)6] were dissolved in acetonitrile, stirred at room temperature, and then filtered to obtain a solid. After drying, the powder was dispersed in deionized water and stirred for 24 hours before being freeze-dried. The resulting yellow-green powder was denoted as [Bmim]3[Fe(CN)6].

5. The preparation method according to claim 4, characterized in that: The high-temperature pyrolysis is carried out at a heating rate of 2–5 °C / min.

6. The preparation method according to claim 1 or 5, characterized in that: The high-temperature pyrolysis is wherein the high-temperature pyrolysis temperature is 400–800°C.

7. The preparation method according to claim 6, characterized in that: The mass ratio of ZIF-67 to carbon black is 1:0.5 to 2.

5.

8. The preparation method according to claim 7, characterized in that: The volume-to-mass ratio of the ionic liquid [Bmim]3[Fe(CN)6] to ZIF-67 / CT is 1:5 to 25.

9. The product obtained by any one of the preparation methods according to claims 1 to 8.

10. The use of the product of claim 9 as an oxygen reduction catalyst.

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