A high-performance single-atom dispersed Fe / N / C catalyst and its preparation method and application

Abstract

The present invention relates to a high-performance single-atom dispersed Fe / N / C catalyst and its preparation method and application, belonging to the technical field of catalysts. The present invention discloses a high-performance single-atom dispersed Fe / N / C catalyst. The high-performance single-atom dispersed Fe / N / C catalyst is a dodecahedron, with a specific surface area of 900 - 1200 m<supgt;2< / supgt> / g, a diameter of 100 - 200 nm; a pore diameter of 3 - 7 nm, and a pore volume of 0.8 - 1.1 cm<supgt;3 / g. The present invention also discloses a preparation method of a high-performance single-atom dispersed Fe / N / C catalyst. The preparation method includes: dissolving ferric nitrate nonahydrate and zinc nitrate hexahydrate in methanol to form solution one, dissolving dimethylimidazole in methanol to form solution two, pouring solution one into solution two and stirring evenly, and performing microwave treatment; then washing, drying the obtained product, and calcining it in a tube furnace to obtain the product.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and relates to a high-performance single-atom dispersed Fe / N / C catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of electronic technology and the wide popularity of various portable electronic products, people's demand for chemical power sources is increasing continuously, and their performance requirements are also constantly improving. In this context, developing a chemical power source system with high specific energy, cleanliness, and safety has become an important requirement for social development. A zinc-air battery is a battery that uses oxygen in the air as the positive electrode active material and metallic zinc as the negative electrode active material. It is a "semi-fuel" battery between a primary battery and a fuel cell, with the characteristics of both a fuel cell and a battery. The air electrode utilizes the reduction of oxygen in the air to output energy, and itself does not consume during the reaction process. Therefore, the capacity of the zinc-air battery only depends on the amount of metallic zinc used. Due to the advantages of high specific energy, stable discharge voltage, low price, and environmental friendliness of the zinc-air battery system, it has become one of the hot systems actively developed in the energy field in recent years and has broad application prospects.

[0003] Since the dissolution of active metals in acids and the electrochemical reaction of oxygen are both better in alkaline solutions than in neutral media, the electrolyte generally uses a high-concentration alkaline solution. The main function of the air electrode is to provide a three-phase reaction interface for the reduction reaction of oxygen during the discharge process. The catalytic activity, cost, and lifespan of the catalyst in the air electrode are one of the key factors restricting metal-air batteries. Currently, platinum group noble metal (PGM) catalysts are still the mainstream commercial catalysts, but they have disadvantages such as high cost and easy poisoning. Therefore, developing inexpensive non-noble metal catalysts to replace PGM catalysts is crucial for the development of a new generation of zinc-air batteries. Among several non-noble metal catalysts, single-atom dispersed transition metal / nitrogen / carbon (M / N / C) catalysts exhibit sufficient activity and durability. In recent years, remarkable progress has been made in adding single-atom iron-nitrogen-carbon (Fe / N / C) catalysts to zinc-air batteries and evaluating their oxygen reduction performance. However, high-performance single-atom dispersed Fe / N / C catalysts often have defects such as long preparation time, uneven heating during the preparation process, and the need for a long acid treatment.

[0004] As disclosed in the Chinese patent application document (Publication No.: CN1138139750A), a ZIF-8-derived hierarchical porous M-N-C catalyst is prepared by dissolving 2-methylimidazole, and preparing an M-MgO@ZIF-8 precursor from zinc nitrate hexahydrate, transition metal salts, and nano-magnesium oxide MgO, and then obtaining a hierarchical porous M-N-C catalyst after carbonization. However, the morphology of the prepared catalyst is not uniform, and the half-wave potential performance is only 0.72V at most. The Chinese patent application document (Publication No.: CN114566654A) also discloses a ZIF-derived edge-rich disc-shaped Fe / Co-N-C electrocatalyst, which is prepared from cobalt nitrate hexahydrate, zinc nitrate hexahydrate, and benzimidazole through room temperature standing and carbonization to obtain a disc-shaped catalyst with a fluffy porous edge. However, its morphology is not uniform, and the half-wave potential performance is only 0.858V at most, still requiring further improvement. In summary, the existing M-N-C catalysts still have problems of unstable morphology and poor performance. Therefore, it is necessary to optimize the preparation method to overcome the adverse factors brought by these defects, and develop a catalyst material with excellent electrochemical properties and structure to rapidly and high-quality prepare Fe / N / C catalysts. Summary of the Invention

[0005] The object of the present invention is to provide a high-performance single-atom dispersed Fe / N / C catalyst in view of the above problems existing in the prior art. The catalyst has a uniform morphology and good performance and can be applied to zinc-air batteries.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A high-performance single-atom dispersed Fe / N / C catalyst, the high-performance single-atom dispersed Fe / N / C catalyst is a dodecahedron, with a specific surface area of 900 - 1200m 2 / g, a diameter of 100 - 200nm; a pore diameter of 3 - 7nm, and a pore volume of 0.8 - 1.1cm 3 / g.

[0008] Preferably, the C content of the high-performance single-atom dispersed Fe / N / C catalyst is 90 - 95%, the N content is 3 - 4.5%, and the Fe content is 0.2 - 2%.

[0009] Preferably, the high-performance single-atom dispersed Fe / N / C catalyst is prepared by calcining a precursor obtained by microwave treatment.

[0010] More preferably, the preparation method of the precursor includes: pouring solution 1 containing iron nitrate nonahydrate and zinc nitrate hexahydrate into solution 2 containing 2-methylimidazole, and performing microwave treatment.

[0011] Preferably, the power of the microwave treatment is 400 - 1000W, and the time is 1 - 10min.

[0012] More preferably, the power of the microwave treatment is 400 - 600 W and the time is 1 - 3 min.

[0013] Different from conventional oil bath heating or oven heating, the microwave treatment adopted in the present invention can instantaneously germinate the nuclei of the precipitate phase, and then synchronously grow all the nuclei of the precipitate phase into particles of a certain shape and size, greatly shortening the preparation period of the precursor. Moreover, the high-energy electromagnetic radiation heating by microwave treatment makes the heating uniform, and the obtained grain size is more uniform and agglomeration is not likely to occur.

[0014] Preferably, the mass ratio of ferric nitrate nonahydrate, zinc nitrate hexahydrate, and 2-methylimidazole is (0.045 - 0.055):(0.5 - 1.0):1.

[0015] More preferably, the mass ratio of ferric nitrate nonahydrate, zinc nitrate hexahydrate, and 2-methylimidazole is (0.045 - 0.055):(0.85 - 0.87):1.

[0016] Preferably, the temperature rising time during the calcination process is longer than the heating time.

[0017] More preferably, during the calcination process, the heating temperature is 1000 - 1300 °C, the temperature rising time is 120 - 240 min, and the heating time is 60 - 150 min.

[0018] By controlling the heating temperature and time of the calcination process, the present invention enables the prepared catalyst to ensure complete structural growth, so that the catalyst has a larger number of active sites, which is beneficial to the progress of the electrochemical reaction. If the calcination temperature is too high, the structure of the generated catalyst is irregular; if the temperature is too low, it is difficult to form the active sites of the catalyst; if the heating time is too long, the structure of the catalyst will be damaged; if the heating time is too short, the structural growth of the catalyst will be incomplete. If a regular dodecahedron structure cannot be formed, the performance of the product is poor and the assembled zinc-air battery cannot function.

[0019] Preferably, the temperature rising time in the first stage is 200 - 250 min.

[0020] Preferably, the calcination is carried out in a nitrogen atmosphere.

[0021] The present invention also discloses a preparation method of a high-performance single-atom dispersed Fe / N / C catalyst. The preparation method includes: dissolving ferric nitrate nonahydrate and zinc nitrate hexahydrate in methanol to form solution one, dissolving 2-methylimidazole in methanol to form solution two, pouring solution one into solution two and stirring evenly, and then performing microwave treatment; then washing, drying the obtained product, and calcining it in a tubular furnace to obtain the product.

[0022] The present invention also discloses an application of a high-performance single-atom dispersed Fe / N / C catalyst in a zinc-air battery.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The high-performance single-atom dispersed Fe / N / C catalyst prepared by the present invention has a porous structure, a large specific surface area, and uniform size.

[0025] 2. By the microwave method of the present invention, the nuclei of the precipitation phase can germinate instantaneously, and then the nuclei of all precipitation phases grow synchronously into particles of a certain shape and size, greatly shortening the preparation cycle of the precursor. Moreover, the high-energy electromagnetic radiation heating by microwave treatment makes the heating uniform, and the obtained grain size is more uniform and not prone to agglomeration.

[0026] 3. By controlling the heating temperature and time in the calcination process, the prepared catalyst of the present invention ensures complete structural growth, so that the catalyst has a large number of active sites, which is beneficial to the progress of the electrochemical reaction.

[0027] 4. The present invention prepares a high-performance single-atom dispersed Fe / N / C catalyst through conventional raw materials and a simple, controllable and highly repeatable preparation process.

[0028] 5. When the high-performance single-atom dispersed Fe / N / C catalyst prepared by the present invention is applied to a zinc-air battery, it has good electrochemical performance.

[0029] Description of the drawings

[0030] Figure 1 It is a scanning electron microscope image (100K) of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0031] Figure 2 It is a scanning electron microscope image (50K) of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0032] Figure 3 It is a transmission electron microscope image of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0033] Figure 4 It is a mapping image of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0034] Figure 5 It is a specific surface area test image of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0035] Figure 6This is the methanol tolerance graph of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0036] Figure 7 This is the cyclic voltammogram of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0037] Figure 8 This is the stability graph of the single-atom dispersed Fe / N / C catalyst prepared in Example 1 of the present invention.

[0038] Figure 9 This is the rate graph of the zinc-air battery prepared in Application Example 1 of the present invention.

[0039] Figure 10 This is the power density graph of the zinc-air battery prepared in Application Example 1 of the present invention.

[0040] Figure 11 This is the open circuit voltage graph of the zinc-air battery prepared in Application Example 1 of the present invention. Detailed implementation manners

[0041] The following are specific examples of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these examples.

[0042] Example 1

[0043] Dissolve 120 mg of iron(III) nitrate nonahydrate and 2.034 g of zinc nitrate hexahydrate in 300 ml of methanol to prepare Solution 1. Dissolve 2.364 g of 2-methylimidazole in 300 ml of methanol to prepare Solution 2. Magnetically stir them at a speed of 800 rpm for 30 min respectively. Then pour Solution 1 into Solution 2 and continue stirring for 15 min. Then place the container containing the mixed solution in a microwave oven with a power of 440 W for 2 min. After cooling, centrifuge and wash three times, and collect the obtained precipitate and dry it at 60 °C. Then place the dried powder in a tube furnace, under a nitrogen atmosphere, heat it to the heating temperature of 1100 °C with a heating-up time of 230 min and a heating time of 120 min, and cool it to room temperature to obtain a high-performance single-atom dispersed Fe / N / C catalyst. The scanning electron microscope image of the high-performance single-atom dispersed Fe / N / C catalyst is as shown in Figure 1-2 shown; the transmission electron microscope image is as shown in Figure 3 shown; the mapping image is as shown in Figure 4 shown. It can be observed that the element distribution is uniform, and the C content is 91.44%, the N content is 3.26%, and the Fe content is 0.21%; the specific surface area test graph is as shown in Figure 5 shown; the methanol tolerance graph is as shown in Figure 6 shown. Perform performance tests on the prepared catalyst. The cyclic voltammogram is as shown in Figure 7 shown, and the stability is as shown inFigure 8 As shown, the half-wave potential is 0.90 V and the limiting current is 6.03 mA / cm 2 .

[0044] Example 2

[0045] Compared with Example 1, the difference is that the microwave power is 100 W. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.79 V and a limiting current of 4.80 mA / cm 2 .

[0046] Example 3

[0047] Compared with Example 1, the difference is that the microwave power is 150 W. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.80 V and a limiting current of 4.89 mA / cm 2 .

[0048] Example 4

[0049] Compared with Example 1, the difference is that the microwave power is 250 W. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.81 V and a limiting current of 5.11 mA / cm 2 .

[0050] Example 5

[0051] Compared with Example 1, the difference is that the microwave power is 350 W. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.83 V and a limiting current of 5.26 mA / cm 2 .

[0052] Example 6

[0053] Compared with Example 1, the difference is that the microwave power is 600 W. The high-performance single-atom dispersed Fe / N / C catalyst was subjected to performance testing, with a half-wave potential of 0.85 V and a limiting current of 5.64 mA / cm 2 .

[0054] Example 7

[0055] Compared with Example 1, the difference is that the microwave time is 1 min. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.83 V and a limiting current of 5.24 mA / cm 2 .

[0056] Example 8

[0057] Compared with Example 1, the difference is that the microwave time is 1.5 min. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.86 V and a limiting current of 5.30 mA / cm 2 .

[0058] Example 9

[0059] Compared with Example 1, the difference is that the microwave time is 1.75 min. The performance of the high-performance single-atom dispersed Fe / N / C catalyst was tested, and the half-wave potential was 0.84 V, and the limiting current was 5.69 mA / cm 2 .

[0060] Example 10

[0061] Compared with Example 1, the difference is that the microwave time is 3 min. The performance of the high-performance single-atom dispersed Fe / N / C catalyst was tested, and the half-wave potential was 0.83 V, and the limiting current was 5.43 mA / cm 2 .

[0062] Example 11

[0063] Compared with Example 1, the difference is that the iron source is ferrous acetate. The prepared catalyst was tested for performance, and the half-wave potential was 0.85 V, and the limiting current was 5.69 mA / cm 2 .

[0064] Example 12

[0065] Compared with Example 1, the difference is that the iron source is ferrous sulfate. The prepared catalyst was tested for performance, and the half-wave potential was 0.90 V, and the limiting current was 5.31 mA / cm 2 .

[0066] Example 13

[0067] Compared with Example 1, the difference is that the addition amount of ferric nitrate nonahydrate is 110 mg. The prepared catalyst was tested for performance, and the half-wave potential was 0.88 V, and the limiting current was 5.60 mA / cm 2 .

[0068] Example 14

[0069] Compared with Example 1, the difference is that the addition amount of ferric nitrate nonahydrate is 130 mg. The prepared catalyst was tested for performance, and the half-wave potential was 0.89 V, and the limiting current was 5.67 mA / cm 2 .

[0070] Example 15

[0071] Compared with Example 1, the difference is that the addition amount of ferric nitrate nonahydrate is 135 mg. The prepared catalyst was tested for performance, and the half-wave potential was 0.87 V, and the limiting current was 5.50 mA / cm 2 .

[0072] Example 16

[0073] Compared with Example 1, the difference is that the addition amount of ferric nitrate nonahydrate is 90 mg. The prepared catalyst was subjected to performance testing, with a half-wave potential of 0.87 V and a limiting current of 5.49 mA / cm 2 .

[0074] Application Example 1

[0075] The high-performance single-atom dispersed Fe / N / C catalyst in Example 1 was made into a zinc-air battery according to a conventional method. The positive electrode of the zinc-air battery was an air electrode, and the negative electrode was a zinc sheet. The zinc-air battery was subjected to performance testing, and its rate performance diagram is as shown in Figure 9 shown, and the power density diagram is as shown in Figure 10 shown, with a power density of 236.81 mW / cm 2 ; the open-circuit voltage diagram is as shown in Figure 11 shown, which is 1.54 V.

[0076] Application Example 2

[0077] Compared with Application Example 1, the difference is that the catalyst of Example 2 was made into a zinc-air battery according to the method of Application Example 1. The zinc-air battery was subjected to performance testing, and the power density was 98.14 mW / cm 2 .

[0078] Application Example 3

[0079] Compared with Application Example 1, the difference is that the catalyst of Example 3 was made into a zinc-air battery according to the method of Application Example 1. The zinc-air battery was subjected to performance testing, and the power density was 109.77 mW / cm 2 .

[0080] Application Example 4

[0081] Compared with Application Example 1, the difference is that the catalyst of Example 4 was made into a zinc-air battery according to the method of Application Example 1. The zinc-air battery was subjected to performance testing, and the power density was 129.52 mW / cm 2 .

[0082] Application Example 5

[0083] Compared with Application Example 1, the difference is that the catalyst of Example 5 was made into a zinc-air battery according to the method of Application Example 1. The zinc-air battery was subjected to performance testing, and the power density was 136.45 mW / cm 2 .

[0084] Application Example 6

[0085] Compared with Application Example 1, the difference is that the catalyst of Example 6 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 180.46 mW / cm 2 .

[0086] Application Example 7

[0087] Compared with Application Example 1, the difference is that the catalyst of Example 7 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 178.35 mW / cm 2 .

[0088] Application Example 8

[0089] Compared with Application Example 1, the difference is that the catalyst of Example 8 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 189.14 mW / cm 2 .

[0090] Application Example 9

[0091] Compared with Application Example 1, the difference is that the catalyst of Example 9 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 192.18 mW / cm 2 .

[0092] Application Example 10

[0093] Compared with Application Example 1, the difference is that the catalyst of Example 10 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 187.24 mW / cm 2 .

[0094] Application Example 11

[0095] Compared with Application Example 1, the difference is that the catalyst of Example 11 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 190.05 mW / cm 2 .

[0096] Application Example 12

[0097] Compared with Application Example 1, the difference is that the catalyst of Example 12 is made into a zinc-air battery according to the method of Application Example 1. The performance of the zinc-air battery is tested, and the power density is 220.74 mW / cm 2 .

[0098] Application Example 13

[0099] Compared with Application Example 1, the difference lies in fabricating a zinc-air battery with the catalyst of Example 13 according to the method of Application Example 1. The performance of the zinc-air battery was tested, and the power density was 215.94 mW / cm 2 .

[0100] Application Example 14

[0101] Compared with Application Example 1, the difference lies in fabricating a zinc-air battery with the catalyst of Example 14 according to the method of Application Example 1. The performance of the zinc-air battery was tested, and the power density was 218.33 mW / cm 2 .

[0102] Application Example 15

[0103] Compared with Application Example 1, the difference lies in fabricating a zinc-air battery with the catalyst of Example 15 according to the method of Application Example 1. The performance of the zinc-air battery was tested, and the power density was 168.27 mW / cm 2 .

[0104] Application Example 16

[0105] Compared with Application Example 1, the difference lies in fabricating a zinc-air battery with the catalyst of Example 16 according to the method of Application Example 1. The performance of the zinc-air battery was tested, and the power density was 159.35 mW / cm 2 .

[0106] Comparative Example 1

[0107] Compared with Example 1, the difference lies in that the heating method of the precursor is oil bath heating, the temperature is 60 °C, and the time is 24 h. The performance of the prepared catalyst was tested, the half-wave potential was 0.83 V, and the limiting current was 5.50 mA / cm 2 .

[0108] Application of Comparative Example 1

[0109] Compared with Application Example 1, the difference lies in fabricating a zinc-air battery with the catalyst of Comparative Example 1 according to the method of Application Example 1. The performance of the zinc-air battery was tested, the power density was 174.01 mW / cm 2 , and the open-circuit voltage was 1.45 V.

[0110] In summary, the high-performance single-atom dispersed Fe / N / C catalyst prepared by the method of the present invention has a porous structure, a large specific surface area, and a relatively large number of active sites, and can have good electrochemical performance when applied to zinc-air batteries.

[0111] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A high-performance single-atom dispersed Fe / N / C catalyst, Characterized in that, The high-performance single-atom dispersed Fe / N / C catalyst is a dodecahedron with a specific surface area of 900-1200 m 2 / g, a diameter of 100-200 nm; a pore diameter of 3-7 nm, and a pore volume of 0.8-1.1 cm 3 / g; The preparation method of the high-performance single-atom dispersed Fe / N / C catalyst includes: Dissolving ferric nitrate nonahydrate and zinc nitrate hexahydrate in methanol to form solution 1, dissolving dimethylimidazole in methanol to form solution 2, pouring solution 1 into solution 2 and stirring evenly, and performing microwave treatment; The power of the microwave treatment is 400 - 1000 W, and the time is 1 - 10 min; then the obtained product is washed, dried, and placed in a tube furnace for calcination to obtain a high-performance single-atom dispersed Fe / N / C catalyst; during the calcination process, the heating temperature is 1000 - 1300 °C, the heating-up time is 120 - 240 min, and the heating time is 60 - 150 min.

2. The high-performance single-atom dispersed Fe / N / C catalyst according to claim 1, Characterized in that, The C content of the high-performance single-atom dispersed Fe / N / C catalyst is 90 - 95%, the N content is 3 - 4.5%, and the Fe content is 0.2 - 2%.

3. The high-performance single-atom dispersed Fe / N / C catalyst according to claim 1, Characterized in that, The mass ratio of ferric nitrate nonahydrate, zinc nitrate hexahydrate, and dimethylimidazole is (0.045 - 0.055):(0.5 - 1.0):

1.

4. The high-performance single-atom dispersed Fe / N / C catalyst according to claim 1, Characterized in that, The power of the microwave treatment is 440 - 600 W, and the time is 1 - 3 min.

5. The high-performance single-atom dispersed Fe / N / C catalyst according to claim 1, Characterized in that, The preparation method of the high-performance single-atom dispersed Fe / N / C catalyst includes: Dissolving 120 mg of ferric nitrate nonahydrate and 2.034 g of zinc nitrate hexahydrate in 300 ml of methanol to form solution 1, dissolving 2.364 g of dimethylimidazole in 300 ml of methanol to form solution 2, magnetically stirring at a rotation speed of 800 rpm for 30 min respectively, then pouring solution 1 into solution 2 and continuing to stir for 15 min, then placing the container containing the mixed solution in a microwave oven with a power of 440 W and a time of 2 min, centrifugally washing three times after cooling, collecting the obtained precipitate and drying it at 60 °C; then placing the dried powder in a tube furnace, in a nitrogen atmosphere, heating to the heating temperature of 1100 °C, with a heating-up time of 230 min and a heating time of 120 min, and cooling to room temperature to obtain a high-performance single-atom dispersed Fe / N / C catalyst.

6. The application of the high-performance single-atom dispersed Fe / N / C catalyst according to any one of claims 1 - 5 in a zinc-air battery.

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