A method for preparing FeZrRu trimetallic bifunctional oxygen electrocatalyst used in zinc-air batteries

Abstract

The present invention adopts a one-step high-temperature pyrolysis method to prepare a trimetallic catalyst with high-efficiency oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional catalytic activity, and the catalyst can be used as an ORR and OER catalyst for the air cathode of a zinc-air battery. The method is to use a mixture of ionic liquid (containing N, S, F, etc.), Fe salt, Zr salt, Ru salt, melamine, thiourea and graphene oxide as a precursor, and obtain a FeZrRu trimetallic bifunctional oxygen electrocatalyst by high-temperature pyrolysis, pickling and annealing. The method of the present invention is simple, and the prepared heteroatom-doped trimetallic bifunctional catalyst has good bifunctional catalytic activity and stability in alkaline conditions, and the self-assembled zinc-air battery also has a higher power density and a relatively stable charge and discharge cycle performance. The present invention provides a general strategy for the synthesis of high-performance trimetallic doped bifunctional oxygen electrocatalysts for metal-air batteries.

Description

Technical Field

[0001] The present invention adopts a one-step high-temperature pyrolysis method to prepare a trimetallic oxygen electrocatalyst with efficient ORR and OER bifunctional catalytic activity, which provides a general strategy for the synthesis of high-performance trimetallic doped bifunctional electrocatalysts for metal-air batteries. Background Art

[0002] In recent years, the energy system has been changing from the absolute dominance of fossil energy to a low-carbon and diversified direction. Among them, energy storage technology is a key link in achieving energy sustainability and environmental protection.

[0003] Metal-air batteries are a popular energy conversion technology with broad prospects for commercial application due to their high specific energy, good safety, and environmental friendliness. Among them, zinc-air batteries have become a major research object among the many categories of metal-air batteries due to their abundant resources and high theoretical energy density.

[0004] Zinc-air batteries (ZABs) have attracted extensive attention due to their advantages such as low cost, high theoretical density, and environmental friendliness. Although zinc-air batteries are expected to become one of the next-generation energy storage devices, the slow oxygen reaction at the cathode still hinders their commercialization. Therefore, efficient catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are urgently needed to improve the performance of ZABs. So far, precious metal materials are still the first choice for commercial electrocatalysts. However, problems such as small reserves, high cost, and single function have hindered their large-scale commercial development. Therefore, finding cheap, low precious metal loading, and efficient bifunctional zinc-air battery catalysts remains a challenge.

[0005] The process of zinc-air battery generating electricity is achieved through the redox reaction between the anode and the cathode. Zinc-air battery is mainly composed of five parts: positive electrode (air electrode), negative electrode (zinc electrode), electrolyte, diaphragm and shell. Among them, the air electrode is the most core part of the zinc-air battery. When the zinc-air battery is discharged, ORR occurs on the air electrode; in addition, when charging, OER occurs on the air electrode.

[0006] In general, during the discharge process of zinc-air batteries, ORR occurs on the electrodes, while during the charging process, OER occurs on the electrodes. As a pair of reversible reactions, they have practical problems such as high overpotential and slow reaction rate in actual production and life, which seriously hinder the further development of zinc-air batteries. Therefore, solving this problem by developing excellent ORR and OER bifunctional catalysts and improving the activity and stability of zinc-air batteries is the focus of many researchers. Summary of the invention

[0007] In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a high-temperature pyrolysis method for preparing a trimetallic catalyst with high-efficiency ORR and OER bifunctional catalytic activity. The method uses a simple one-pot pyrolysis method to synthesize graphene oxide (GO), ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide) ([BMIM]TF 2 N)), (ferrocenylmethyl)trimethylammonium iodide (C 14 H 20 FeIN), Zr(NO 3 ) 4 Solution, RuCl 3 The catalyst powder obtained by pyrolysis of the solution, melamine and thiourea is stirred and dried, and then acid-washed and secondary annealed to obtain the final catalyst. Magnetic stirring can better adsorb ionic liquids and metal salts on the GO surface to obtain a uniform precursor. Ionic liquids can effectively prevent GO from agglomerating during pyrolysis. At the same time, they can dope N, S, F and other heteroatoms into carbon carriers during pyrolysis to form N, S, F co-doped carbon materials. Melamine supplements the N source and thiourea supplements the S source, which is beneficial to the doping of heteroatoms. After the addition of Zr element, there will be an interaction between Fe and Zr, and the iron atom species and ZrO 2 There is charge transfer between nanoparticles. At the same time, the addition of Zr can increase the charge density near Fe in the bimetallic doped catalyst, thereby reducing the binding energy of Fe and Zr. 2 There is a strong interaction between the nanoclusters. The incorporation of the third metal element Ru did not have a significant effect on the ORR performance of the FeZr catalyst. The FeZrRu (2%) catalyst still retained the ZrO that promoted the ORR activity. 2 At the same time, it has a more excellent OER electrocatalytic performance, and there is an interactive relationship between Ru species and Fe elements, which are firmly connected to the catalyst surface. The strong interaction between the metal and the carrier can improve the activity of the catalyst by adjusting the electronic structure of carbon and the d orbital of the metal.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] The high temperature pyrolysis method is used to prepare a trimetallic catalyst with bifunctional catalytic activity, which is characterized by the following specific steps:

[0010] (1) dispersing 40-70 mg of few-layer graphene oxide in 10 ml of ultrapure water, and using ultrasound to fully disperse it in the solvent;

[0011] (2) 40-70 mg (ferrocenylmethyl) trimethylammonium iodide (C 14 H 20FeIN) was dissolved in 2.5 ml of anhydrous ethanol and fully dissolved by ultrasound;

[0012] (3) Prepare 0.1M-0.5M Zr(NO 3 ) 4 solution and 8mM-10mM RuCl 3 Solution, set aside;

[0013] (4) Take a certain amount of (ferrocenylmethyl)trimethylammonium iodide (C 14 H 20 FeIN) / ethanol solution was added to the graphene oxide suspension, and then Zr(NO 3 ) 4 Solution, RuCl 3 solution, 1-5 ml ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide) ([BMIM][NF 2 T])), melamine and thiourea, mixed with magnetic stirring for 24h.

[0014] (5) After the stirring is completed, the suspension is placed in a 40-70° C. forced air drying oven to dry the water therein;

[0015] (6) Transfer it to a crucible and heat it in a tube furnace. 2 Or in Ar atmosphere, heat up to 600-1000℃ at a rate of 2-5℃ / min and keep at that temperature for 1h, then cool down naturally;

[0016] (7) grinding after pyrolysis, then acid washing, washing with ultrapure water after acid washing, transferring to a petri dish, drying in a forced air drying oven at 40-70° C., and grinding again;

[0017] (8) Finally, it is subjected to secondary annealing in a tube furnace. 2 Or in an Ar atmosphere, the temperature is raised to 600-1000°C at a heating rate of 2-5°C / min and kept for 1 hour, then naturally cooled, and a FeZrRu trimetallic catalyst is obtained after grinding.

[0018] In the step (1), the ultrasonic treatment time of GO is more than 2 hours;

[0019] In step (2), C 14 H 20 The ultrasonic time of FeIN is more than 2 h, until it is completely dissolved;

[0020] In step (3), Zr(NO 3 ) 4 The solution concentration is 0.1M-0.5M;

[0021] In step (3), RuCl 3 The solution concentration is 8mM-10mM;

[0022] The (ferrocenylmethyl)trimethylammonium iodide (C 14 H 20 The concentration of FeIN) / ethanol solution is 16-28 mg / ml, and the amount added is 1-5 ml;

[0023] The Zr(NO 3 ) 4 The solution is 1-5ml;

[0024] The RuCl in step (4) 3 The solution is 0.1-2ml;

[0025] The ionic liquid in step (4) is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide) ([BMIM][NF 2 T]), the amount added is 1-5ml;

[0026] The amount of melamine added in step (4) is 100-500 mg;

[0027] The amount of thiourea added in step (4) is 100-250 mg;

[0028] The magnetic stirring time in step (4) is 24 hours;

[0029] In step (5), the temperature of the blast drying oven is 40-70° C., and the time is indefinite, until the moisture is dried;

[0030] The heating rate of the tubular furnace in step (6) is 2-5°C / min, and the atmosphere is N 2 or Ar, the pyrolysis temperature is 600-1000℃, and the holding time is 1h.

[0031] The pickling solution in step (7) is 0.5 MH 2 SO 4 The ratio of acid washing is 1mg catalyst: 1ml0.5MH 2 SO 4 , pickling temperature is 60-90℃, pickling time is 5-8h, and the condition is oil bath magnetic stirring;

[0032] In the step (7), the filter needs to be rinsed with ultrapure water for more than 5 times;

[0033] In step (7), the temperature of the blast drying oven is 40-70° C. and the drying time is 3-4 hours;

[0034] The heating rate of the tubular furnace for the secondary annealing in step (8) is 5°C / min, and the atmosphere is N 2 or Ar, the pyrolysis temperature is 600-1000℃, and the holding time is 1h.

[0035] The grinding time in step (8) is 10-30 min.

[0036] The C 14 H 20 FeIN, [BMIM] [NF 2 T]、Zr(NO 3 ) 4 Pentahydrate, RuCl 3 Trihydrate, melamine and thiourea were all analytical grade reagents.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] (1) The one-pot pyrolysis multi-metal ion liquid impregnation graphene oxide technology adopted by the present invention can effectively and conveniently prepare zinc-air battery anode and cathode bifunctional catalysts. Ionic liquids are green and non-toxic, can effectively control the surface morphology of materials, and can be dispersed and contacted with different materials without surfactants. At the same time, the heteroatoms contained therein can effectively prevent metal agglomeration during the pyrolysis process.

[0039] (2) Adding melamine and thiourea to the precursor is beneficial to increasing the doping of heteroatoms N and S in the catalyst. At the same time, the incorporation of N and S also improves the electrocatalytic performance of the catalyst.

[0040] (3) There is an interaction between Fe and Zr. The iron atomic species and ZrO 2 There is charge transfer between nanoparticles. At the same time, there is an interactive relationship between Ru species and Fe elements, which are firmly connected to the catalyst surface. The strong metal-support interaction can improve the activity of the catalyst by adjusting the electronic structure of carbon and the d orbital of the metal.

[0041] (4) The addition of the third metal element Ru did not have a significant effect on the ORR performance of the FeZr catalyst, and the catalyst still retained the ZrO that promoted the ORR activity. 2 Nanoclusters. At the same time, it has better OER electrocatalytic performance.

[0042] (5) The catalyst has a large carbon defect density, which is beneficial to the mass transfer of electrons in the catalyst and improves the stability of the catalyst.

[0043] (6) Ionic liquids are also used as pore-forming agents to give the catalyst a good porous structure, thereby enhancing the catalyst's kinetic properties and durability. At the same time, they can expose more active sites on the catalyst and improve the catalyst's catalytic activity.

[0044] (7) The experimental method of the present invention is simple, has low requirements on experimental equipment, and the synthesized catalyst has a stable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 XRD patterns of Example 1 (catalyst FeZrRu / C-2%), Comparative Example 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) and Comparative Example 2 (catalysts FeZr / C and Ru / C);

[0046] Figure 2 Field emission scanning electron microscope (FE-SEM) images of Example 1 of the present invention (catalyst FeZrRu / C-2%) and Comparative Example 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%);

[0047] Figure 3 It is a transmission electron microscope (TEM) image of Example 1 (catalyst FeZrRu / C-2%) of the present invention;

[0048] Figure 4 The Raman curves of Example 1 (catalyst FeZrRu / C-2%) and Comparative Example 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) of the present invention are shown in FIG. Figure 4 a) and nitrogen adsorption / desorption curves of Example 1 (catalyst FeZrRu / C-2%) ( Figure 4 b);

[0049] Figure 5 The ORR polarization curves of Example 1 (catalyst FeZrRu / C-2%), Comparative Example 1 (catalyst FeZrRu / C-1% and FeZrRu / C-5%) and Comparative Example 2 (Ru / C) of the present invention are shown in FIG. Figure 5 a); Methanol resistance curve of implementation case 1 (catalyst FeZrRu / C-2%) ( Figure 5 b); Comparison of the stability of implementation case 1 (catalyst FeZrRu / C-2%) and commercial Pt / C ( Figure 5 c);

[0050] Figure 6RRDE test of Example 1 of the present invention (catalyst FeZrRu / C-2%) and Comparative Example 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) ( Figure 6 a) and Tafel slope curve ( Figure 6 b);

[0051] Figure 7 The OER polarization curves of Example 1 (catalyst FeZrRu / C-2%), Comparative Example 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) and Comparative Example 2 (catalysts FeZr / C and Ru / C) of the present invention are shown in FIG. Figure 7 a), Tafel slope curves of implementation case 1 (catalyst FeZrRu / C-2%) and comparative implementation case 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) ( Figure 7 b) and the impedance curves of implementation case 1 (catalyst FeZrRu / C-2%), comparative implementation case 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) and comparative implementation case 2 (catalysts FeZr / C and Ru / C) ( Figure 7 c);

[0052] Figure 8 The Cdl value comparison diagram of the embodiment 1 of the present invention (catalyst FeZrRu / C-2%), the comparative embodiment 1 (catalysts FeZrRu / C-1% and FeZrRu / C-5%) and the comparative embodiment 2 (catalysts FeZr / C and Ru / C) is shown in FIG. Figure 8 a) and OER stability diagram of implementation case 1 (catalyst FeZrRu / C-2%) ( Figure 8 b);

[0053] Fig. 9 Polarization curves and power density diagrams of zinc-air batteries self-assembled from Example 1 of the present invention (catalyst FeZrRu / C-2%) and commercial Pt / C ( Fig. 9 a) Open circuit voltage ( Fig. 9 b) and charge-discharge cycle stability diagram ( Fig. 9 c). DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0055] Implementation Case 1

[0056] Using [BMIM][NF 2 T]、C 14 H 20 FeIN, Zr(NO 3 )4 Solution, RuCl 3 A method for preparing a FeZrRu trimetallic bifunctional oxygen electrocatalyst for zinc-air batteries using a solution, melamine and thiourea, the specific steps of which are as follows:

[0057] (1) dispersing 40-70 mg of few-layer graphene oxide in 10 ml of ultrapure water, and using ultrasound to fully disperse it in the solvent;

[0058] (2) 40-70 mg (ferrocenylmethyl) trimethylammonium iodide (C 14 H 20 FeIN) was dissolved in 2.5 ml of anhydrous ethanol and fully dissolved by ultrasound;

[0059] (3) Prepare 0.1M-0.5M Zr(NO 3 ) 4 solution and 8mM-10mM RuCl 3 Solution, set aside;

[0060] (4) Take a certain amount of (ferrocenylmethyl)trimethylammonium iodide (C 14 H 20 FeIN) / ethanol solution was added to the graphene oxide suspension, and then Zr(NO 3 ) 4 Solution, RuCl 3 solution, 1-5 ml ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide) ([BMIM][NF 2 T])), melamine and thiourea, mixed with magnetic stirring for 24h.

[0061] (5) After the stirring is completed, the suspension is placed in a 40-70° C. forced air drying oven to dry the water therein;

[0062] (6) Transfer it to a crucible and heat it in a tube furnace. 2 Or in Ar atmosphere, heat up to 600-1000℃ at a rate of 2-5℃ / min and keep at that temperature for 1h, then cool down naturally;

[0063] (7) grinding after pyrolysis, then acid washing, washing with ultrapure water after acid washing, transferring to a petri dish, drying in a forced air drying oven at 40-70° C., and grinding again;

[0064] (8) Finally, it is subjected to secondary annealing in a tube furnace. 2 Or in an Ar atmosphere, the temperature is raised to 600-1000°C at a heating rate of 2-5°C / min and kept for 1 hour, then naturally cooled, and a FeZrRu trimetallic catalyst is obtained after grinding.

[0065] Comparative implementation case 1

[0066] (1) Reduce RuCl 3 The amount of solution added during the preparation of FeZrRu / C-2% was changed in step (4) except for the amount of RuCl 3 Except for the amount of solution added, other steps and parameters were consistent with those in Example 1 to obtain the catalyst FeZrRu / C-1%.

[0067] (2) Increase the RuCl 3 The amount of solution added during the preparation of FeZrRu / C-2% was changed in step (4) except for the amount of RuCl 3 Except for the amount of solution added, other steps and parameters were consistent with those in Example 1 to obtain a catalyst FeZrRu / C-5%.

[0068] Comparative implementation case 2

[0069] (1) Without adding RuCl 3 Solution, in the preparation process of FeZrRu / C-2%, except that RuCl is not added in step (4) 3 Except for the solution, other steps and parameters were the same as those in Example 1 to obtain the catalyst FeZr / C.

[0070] (2) Without C 14 H 20 FeIN and Zr(NO 3 ) 4 Solution, in the preparation process of FeZrRu / C-2%, except that C is not added in step (4), 14 H 20 FeIN and Zr(NO 3 ) 4 Except for the solution, other steps and parameters were consistent with those in Example 1 to obtain the catalyst Ru / C.

Claims

1. A method for preparing a FeZrRu trimetallic bifunctional oxygen electrocatalyst for use in zinc-air batteries. Features The specific steps are as follows: (1) dispersing 30-100 mg of graphene oxide in 10 ml of ultrapure water and fully dispersing it in the solvent using ultrasound; (2) 40-70 mg (ferrocenylmethyl) trimethylammonium iodide (C 14 H 20 FeIN) was dissolved in 2.5 ml of anhydrous ethanol and fully dissolved by ultrasound; (3) Prepare 0.1M-0.5M Zr(NO 3 ) 4 solution and 8mM-10mM RuCl 3 Solution, set aside; (4) Take a certain amount of (ferrocenylmethyl)trimethylammonium iodide (C 14 H 20 FeIN) / ethanol solution was added to the graphene oxide suspension, and then Zr(NO 3 ) 4 Solution, RuCl 3 solution, 1-5 ml ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide) ([BMIM][NF 2 T])), melamine and thiourea, mixed with magnetic stirring for 24h; (5) After the stirring is completed, the suspension is placed in a 40-70° C. forced air drying oven to dry the water therein; (6) Transfer it to a crucible and heat it in a tube furnace. 2 Or in Ar atmosphere, heat up to 600-1000℃ at a rate of 2-5℃ / min and keep at that temperature for 1h, then cool down naturally; (7) After pyrolysis, the mixture was ground and then acid washed (0.3-1M H 2 SO 4 ), after the acid wash, wash with ultrapure water for more than 5 times, transfer to a culture dish, place in a forced air drying oven at 40-70°C for drying, and grind again; (8) Finally, it is subjected to secondary annealing in a tube furnace. 2 Or in an Ar atmosphere, the temperature is raised to 600-1000°C at a heating rate of 2-5°C / min and kept for 1 hour, then naturally cooled, and a FeZrRu trimetallic catalyst is obtained after grinding.

Images