Coordination polymer coated twisted poly-pyrrole nanotube derived catalytic material, preparation method and application thereof

Abstract

This invention discloses a coordination polymer-coated catalytic material derived from twisted polypyrrole nanotubes, its preparation method, and its applications. First, using a chiral surfactant as a template, a helical polymer structure is formed by inducing polymer monomers to act as the core. Then, a transition metal source is introduced to further assemble a helical support. Next, an organic ligand is used for coordination coating to form a shell. Finally, after pyrolysis under an inert gas, a dense twisted carbon layer is formed at the core-shell interface, yielding the coordination polymer-coated catalytic material derived from twisted polypyrrole nanotubes. The introduction of the helical core in this catalytic material not only helps form a twisted carbon interface but also helps induce a uniform distribution of transition metal active sites. The preparation method of this invention is convenient, and the obtained catalytic material exhibits good oxygen reduction / evolution bifunctional catalytic activity, stability, and applicability to flexible zinc-air batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, specifically relating to a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer, which exhibits good oxygen reduction / evolution bifunctional catalytic activity, stability, and applicability to flexible zinc-air batteries. Background Technology

[0002] With the rapid development of the economy and society, electronic devices are moving towards greater convenience, miniaturization, and flexibility. In recent years, flexible zinc-air batteries have become ideal candidate materials due to their high theoretical energy density, flexibility, and safety. However, slow kinetic processes and poor stability in this battery system currently severely hinder its practical application. Therefore, developing electrocatalysts with high ORR / OER activity is crucial, but remains a significant challenge. In general, Pt-based electrocatalysts have exhibited good electrocatalytic performance; however, their high cost limits their large-scale application. In recent years, transition metal nitrogen co-doped carbon (MNC) materials have emerged as a promising alternative material for the air electrode in zinc-air batteries due to their high activity, low cost, and high stability.

[0003] Methods for preparing MNC electrocatalysts include pyrolysis, liquid-phase exfoliation, electrochemical deposition, thermal synthesis, and wet chemical methods. Among these, the pyrolysis of coordination polymers, metal-organic frameworks (MOFs), and mixtures of metal salts and organic molecules under Ar / N2 conditions can prepare MNC electrocatalysts with unique morphologies. Studies have shown that introducing interfaces between different components in hybrid materials such as polymer / MOF and MOF / MOF can form dense carbon layers at the interfaces. Importantly, changing the curvature of the interface can easily adjust the catalytic curvature of the electrocatalyst. Recently, related studies have shown that changing the curvature of the interface affects the activity and selectivity of the electrocatalyst. For example, Zeng et al. developed a fullerene-like structure composed of a MoS2 layer and Cu single atoms, which exhibited selectivity from CO2 to methanol; Feng et al. prepared a highly tortuous porous carbon material with single-metal FeN4 sites, achieving high ORR activity and stability. However, most reported hybrid materials used as precursors for MNC electrocatalysts typically have low contents of these heterogeneous interfaces. Therefore, constructing highly efficient electrocatalysts with high-content heterogeneous interfaces (such as high-curvature surfaces and helical surfaces) with unique curvature is of profound significance. Summary of the Invention

[0004] The purpose of this invention is to provide a convenient, low-cost, uniquely morphological, and highly catalytically active coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material and its preparation method, so as to improve the ORR / OER dual catalytic activity, stability, and applicability of flexible zinc-air batteries.

[0005] To achieve the above objectives, the coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material provided by the present invention is prepared by the following method:

[0006] Step 1: At room temperature, dissolve the chiral surfactant in methanol, then add pyrrole and deionized water, stir until a homogeneous solution is formed, then add ammonium persulfate aqueous solution pre-cooled to 0-5℃, continue stirring until dissolved, filter under reduced pressure and wash, and dry the resulting black solid to obtain helical polypyrrole nanotubes; wherein, the chiral surfactant is a C-linking surfactant. 12 ~C 18 Chiral amino acids with carbon chains;

[0007] Step 2: Disperse the helical polypyrrole nanotubes obtained in Step 1 in methanol, then add a metal salt, stir for 4-7 hours, then centrifuge, wash and dry to obtain helical polypyrrole nanotubes with metal ions modified on the surface; wherein, the metal salt is any one of cobalt nitrate and zinc nitrate;

[0008] Step 3: Disperse the surface-modified helical polypyrrole nanotubes obtained in Step 2 in methanol, then add a methanol solution of 2-methylimidazole, stir continuously for 10-14 hours, filter, wash and dry to obtain helical polypyrrole coated with a coordination polymer layer.

[0009] Step 4: The spiral polypyrrole coated with the coordination polymer layer obtained in Step 3 is loaded into a ceramic boat, and then pyrolyzed in a tube furnace filled with Ar at 800-900°C for 2-3 hours to obtain a catalytic material derived from coordination polymer coated twisted polypyrrole nanotubes.

[0010] In step 1 above, the chiral amino acid is selected from any one of D-alanine, L-alanine, D-glutamic acid, L-glutamic acid, D-phenylalanine, L-phenylalanine, D-lysine, and L-lysine.

[0011] Furthermore, in step 1 above, the preferred molar ratio of the chiral surfactant to pyrrole and ammonium persulfate is 1:25–60:25–60, the volume ratio of methanol to deionized water is 1:3–7, and the concentration of the chiral surfactant in methanol is 3.0 × 10⁻⁶. -3 ~8.5×10 -3 mol / L.

[0012] Furthermore, in step 2 above, the preferred mass ratio of the metal salt to the helical polypyrrole nanotubes is 1:0.05 to 0.3.

[0013] Furthermore, in step 3 above, the preferred molar ratio of the 2-methylimidazole to the metal salt in step 2 is 1:0.05 to 0.4.

[0014] Furthermore, in steps 2 and 3 above, the drying temperature is preferably 60-80°C, and the drying time is 12-24 hours.

[0015] Furthermore, in step 4 above, the preferred pyrolysis heating rate is 2-5 °C / min.

[0016] The catalytic material derived from the coordination polymer-coated twisted polypyrrole nanotubes of this invention can be used as an air cathode material in the preparation of flexible new air batteries.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention first uses a chiral surfactant as a template to induce the self-assembly of polymer monomers to form a helical polymer that serves as the core. Then, a transition metal source is introduced to further assemble a helical support. Next, organic ligands are introduced for coordination coating to form a shell. Finally, after pyrolysis under an inert gas, a dense, twisted carbon layer is formed at the core-shell interface. The introduction of the helical core not only helps form a twisted carbon interface but also helps induce a uniform distribution of transition metal active sites. The preparation method of this invention is convenient and novel. The catalytic material has a dense, twisted carbon layer structure with uniformly distributed cobalt transition metal catalytic active sites embedded within it, exhibiting good oxygen reduction / evolution bifunctional catalytic activity, stability, and applicability to flexible zinc-air batteries. Attached Figure Description

[0019] Figure 1 These are SEM images of HPPy(a) and HPPy@Co-MIM(b) obtained in Example 1.

[0020] Figure 2 This is a TEM image of HCNT@Co-NC obtained in Example 1.

[0021] Figure 3 The ORR and OER polarization curves of HCNT@Co-NC obtained in Example 1, Co-NC obtained in Comparative Example 1, and HCNT obtained in Comparative Example 2 in O2-saturated 0.1M KOH solution are shown.

[0022] Figure 4 The image is a SEM image of HCNT@Co-NC obtained in Example 1 after 2000 CV cycles.

[0023] Figure 5 The flexible zinc-air battery with the HCNT@Co-NC-based air cathode obtained in Example 1 operates at 1 mA cm⁻¹. -2 Stability test under current density.

[0024] Figure 6 This is a stability test of the flexible zinc-air battery with HCNT@Co-NC based air cathode obtained in Example 1 at different bending angles. Detailed Implementation

[0025] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. The following content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined by the claims, all of which should fall within the protection scope of the present invention.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0027] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0028] The electrochemical performance tests of the air batteries in the following examples were all performed using the Chenhua testing system.

[0029] Example 1

[0030] Step 1: Weigh 0.0245g (0.074mmol) C 18 L-glutamic acid (Angew. Chem. Int. Ed. 2018, 57, 13187-13191) was dissolved in 12 mL of methanol and stirred for 30 minutes to obtain a homogeneous solution. Then, 166 μL (2.4 mmol) of pyrrole and 60 mL of deionized water were slowly added, and stirring was continued for 10 minutes. Subsequently, 1.2 mL of an aqueous solution containing 0.548 g (2.4 mmol) of ammonium persulfate, which had been pre-cooled at 0 °C, was slowly added, and stirring was continued for 30 minutes to obtain a black suspension. Finally, the suspension was filtered, washed with water and ethanol, and dried at 60 °C for 12 hours to obtain helical polypyrrole nanotubes (HPPy).

[0031] Step 2: Weigh 30 mg of HPPy obtained in Step 1 and add it to 10 mL of methanol. Sonicate for 30 minutes to disperse it evenly. Then add 0.29 g (1 mmol) of Co(NO)3·6H2O and stir continuously for 5 hours. Finally, centrifuge and wash with methanol to obtain spiral polypyrrole nanotubes (HPPy@Co) with metal ions modified on the surface.

[0032] Step 3: Disperse the precursor HPPy@Co obtained in Step 2 in 5 mL of methanol, then add 10 mL of methanol solution containing 0.82 g (10 mmol) of 2-methylimidazole, stir continuously for 12 hours, finally filter the mixture and wash it with methanol, and dry it at 60 °C for 24 hours to obtain helical polypyrrole (HPPy@Co-MIM) coated with a coordination polymer layer.

[0033] Step 4: Place the HPPy@Co-MIM obtained in Step 3 into a ceramic boat, and then heat it to 900℃ in a tube furnace filled with Ar at a heating rate of 3℃ / min and hold for 2h to obtain a cobalt coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material (HCNT@Co-NC).

[0034] Comparative Example 1

[0035] 0.29 mg (1 mmol) Co(NO)3·6H2O and 0.33 g (4 mmol) 2-methylimidazole were dissolved in 15 mL of methanol solution respectively. Then, the methanol solution containing 2-methylimidazole was slowly added to the methanol solution containing Co(NO)3·6H2O. After stirring for 5 minutes, the mixture was allowed to stand for 24 hours for aging. After centrifugation, washing with methanol, and drying at 60 °C for 12 hours, the precursor ZIF-67 was obtained. The precursor ZIF-67 was placed in a ceramic boat and heated to 900 °C for 2 hours in a tube furnace filled with Ar at a heating rate of 3 °C / min to obtain cobalt-nitrogen co-doped carbon material (Co-NC).

[0036] Comparative Example 2

[0037] The helical polypyrrole nanotubes (HPPy) obtained in step 1 of Example 1 were placed in a ceramic boat and heated to 900°C in a tube furnace filled with Ar at a heating rate of 3°C / min and held for 2 hours to obtain pure carbon material (HCNT).

[0038] Figure 1 (a) is a SEM image of HPPy obtained in Example 1. Figure 1 (b) is a SEM image of HPPy@Co-MIM obtained in Example 1. By comparison, it can be found that the diameter of the single helical nanotube has changed significantly, but the helical morphology is well preserved, indicating that the coordination polymer coating layer has been successfully grown in situ on the outer surface of the helical HPPy structure.

[0039] Figure 2 The TEM image of HCNT@Co-NC obtained in Example 1 shows that after pyrolysis treatment, the helical structure of the inner template in HCNT@Co-NC is well replicated, and a tight twisted interface carbon configuration is formed at the interface between the inner template and the outer coordination polymer.

[0040] Figure 3 The test curves show the catalytic performance of HCNT@Co-NC obtained in Example 1, Co-NC obtained in Comparative Example 1, and HCNT obtained in Comparative Example 2. It can be seen that the catalytic material obtained in Example 1 has better bifunctional catalytic activity compared with the comparative example.

[0041] Figure 4 The image shown is a SEM image of HCNT@Co-NC obtained in Example 1 after 2000 CV cycles. It can be seen that the helical structure of the catalyst is well preserved, indicating that HCNT@Co-NC prepared in Example 1 has good structural stability.

[0042] Example 2

[0043] In step 2 of this embodiment, 0.3 g (1 mmol) Zn(NO)3·6H2O was used to replace Co(NO)3·6H2O in Example 1. The other steps were the same as in Example 1, and a zinc coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material (HCNT@Zn-NC) was obtained.

[0044] Example 3

[0045] Step 1: Weigh 0.01g (0.039mmol) C 18 -L-glutamic acid was dissolved in 12 mL of methanol and stirred for 30 minutes to obtain a homogeneous solution. Then, 150 μL (2.2 mmol) of pyrrole and 45 mL of deionized water were slowly added and stirred for another 10 minutes. Subsequently, 1.2 mL of an aqueous solution containing 0.456 g (2 mmol) of ammonium persulfate, which had been pre-cooled at 5 °C, was slowly added and stirred for another 30 minutes to obtain a black suspension. Finally, the suspension was filtered, washed with water and ethanol, and dried at 60 °C for 12 hours to obtain helical polypyrrole nanotubes (HPPy).

[0046] Step 2: Weigh 30 mg of HPPy obtained in Step 1 and add it to 10 mL of methanol. Sonicate for 30 minutes to disperse it evenly. Then add 0.23 g (0.8 mmol) Co(NO)3·6H2O and stir continuously for 4 hours. Finally, centrifuge and wash with methanol to obtain spiral polypyrrole nanotubes (HPPy@Co) with metal ions modified on the surface.

[0047] Step 3: Disperse the precursor HPPy@Co obtained in Step 2 in 5 mL of methanol, then add 10 mL of methanol solution containing 0.26 g (3.2 mmol) 2-methylimidazole, stir continuously for 10 hours, finally filter the mixture and wash it with methanol, and dry it at 60 °C for 12 hours to obtain helical polypyrrole (HPPy@Co-MIM) coated with a coordination polymer layer.

[0048] Step 4: Place the HPPy@Co-MIM obtained in Step 3 into a ceramic boat, and then heat it to 800℃ in a tube furnace filled with Ar at a heating rate of 3℃ / min and hold for 3h to obtain a cobalt coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material (HCNT@Co-NC).

[0049] Example 4

[0050] Step 1: Weigh 0.04g (0.1mmol) C 18 -L-glutamic acid was dissolved in 12 mL of methanol and stirred for 30 minutes to obtain a homogeneous solution. Then, 180 μL (2.6 mmol) of pyrrole and 75 mL of deionized water were slowly added and stirred for another 10 minutes. Subsequently, 1.2 mL of an aqueous solution containing 0.685 g (3 mmol) of ammonium persulfate, which had been pre-cooled at 0 °C, was slowly added and stirred for another 30 minutes to obtain a black suspension. Finally, the suspension was filtered, washed with water and ethanol, and dried at 60 °C for 12 hours to obtain helical polypyrrole nanotubes (HPPy).

[0051] Step 2: Weigh 30 mg of HPPy obtained in Step 1 and add it to 10 mL of methanol. Sonicate for 30 minutes to disperse it evenly. Then add 0.44 g (1.5 mmol) Co(NO)3·6H2O and stir continuously for 7 hours. Finally, centrifuge and wash with methanol to obtain spiral polypyrrole nanotubes (HPPy@Co) with metal ions modified on the surface.

[0052] Step 3: Disperse the precursor HPPy@Co obtained in Step 2 in 5 mL of methanol, then add 10 mL of methanol solution containing 1.48 g (18 mmol) of 2-methylimidazole, stir continuously for 14 hours, finally filter the mixture and wash it with methanol, and dry it at 80 °C for 20 hours to obtain helical polypyrrole (HPPy@Co-MIM) coated with a coordination polymer layer.

[0053] Step 4: Place the HPPy@Co-MIM obtained in Step 3 into a ceramic boat, and then heat it to 900℃ in a tube furnace filled with Ar at a heating rate of 5℃ / min and hold for 2h to obtain a cobalt coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material (HCNT@Co-NC).

[0054] Example 5

[0055] Step 1: Weigh 0.03g (0.0834mmol) C 18-L-glutamic acid was dissolved in 12 mL of methanol and stirred for 30 minutes to obtain a homogeneous solution. Then, 170 μL (2.5 mmol) of pyrrole and 60 mL of deionized water were slowly added, and stirring was continued for 10 minutes. Subsequently, 1.2 mL of an aqueous solution containing 0.639 g (2.8 mmol) of ammonium persulfate, which had been pre-cooled at 3 °C, was slowly added, and stirring was continued for 30 minutes to obtain a black suspension. Finally, the suspension was filtered, washed with water and ethanol, and dried at 60 °C for 12 hours to obtain helical polypyrrole nanotubes (HPPy).

[0056] Step 2: Weigh 30 mg of HPPy obtained in Step 1 and add it to 10 mL of methanol. Sonicate for 30 minutes to disperse it evenly. Then add 0.35 g (1.2 mmol) Co(NO)3·6H2O and stir continuously for 6 hours. Finally, centrifuge and wash with methanol to obtain spiral polypyrrole nanotubes (HPPy@Co) with metal ions modified on the surface.

[0057] Step 3: Disperse the precursor HPPy@Co obtained in Step 2 in 5 mL of methanol, then add 10 mL of methanol solution containing 0.79 g (9.6 mmol) 2-methylimidazole, stir continuously for 12 hours, finally filter the mixture and wash it with methanol, and dry it at 75 °C for 20 hours to obtain helical polypyrrole (HPPy@Co-MIM) coated with a coordination polymer layer.

[0058] Step 4: Place the HPPy@Co-MIM obtained in Step 3 into a ceramic boat, and then heat it to 850℃ in a tube furnace filled with Ar at a heating rate of 5℃ / min and hold for 2h to obtain a cobalt coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material (HCNT@Co-NC).

[0059] Example 6

[0060] Application of the coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material prepared in Example 1 as an air cathode material in the preparation of flexible zinc-air batteries.

[0061] 0.67 g of polyvinyl alcohol was dissolved in 20 mL of deionized water and heated and stirred in a 90 °C water bath for 2 hours to obtain a transparent solution. The transparent solution was then cooled to 60 °C, and 10.08 g of acrylic acid, 11 mL of 8.4 mol / L sodium hydroxide aqueous solution, and 0.025 g of N,N-methylenebisacrylamide were added sequentially, with stirring continued for half an hour. After cooling to room temperature, 5 mL of 0.15 mol / L ammonium persulfate aqueous solution was added, and the mixture was stirred at room temperature for 40 minutes. The resulting solution was then poured into a template and dried at 70 °C to form a gel (an 8 cm petri dish was used in this experiment, with a solution thickness of 3 mm). Finally, the gel was immersed in an aqueous solution containing 4 mol / L KOH and 2 mol / L KI for 24 hours to obtain a gel electrolyte, which was then cut into 2 cm × 2 cm squares for later use.

[0062] Assembly of the flexible battery: The anode is a 0.8mm thick zinc foil, cut into 2cm × 4cm pieces, and sanded to remove surface oxides before use. A catalyst slurry (ratio: 4mg catalyst, 450μL ethanol, and 50μL Nafion) is loaded onto nickel foam (0.8mm thick, 2cm × 4cm) to form an independent cathode, which is then dried at room temperature. Finally, the prepared cathode, anode, and electrolyte are assembled, secured at both ends using non-conductive PTFE tape or sealing film, ensuring close contact between the catalyst and electrolyte.

[0063] Electrochemical testing was conducted at room temperature on a CHI 660E electrochemical workstation. Cyclic stability testing consisted of 20-minute cycles, including 10-minute charge and 10-minute discharge cycles, with a current density of 1 mA cm⁻¹. -2 .

[0064] Figure 5 The stability test of the flexible zinc-air battery assembled using HCNT@Co-NC obtained in Example 1 as the air cathode was conducted. The comparison revealed that, compared to the Pt / C+Ir / C-based air cathode flexible zinc-air battery, the HCNT@Co-NC-based battery exhibited a lower voltage gap and a longer cycle life, indicating that HCNT@Co-NC has good applicability in flexible zinc-air batteries.

[0065] Figure 6 The stability test of the flexible zinc-air battery assembled with HCNT@Co-NC obtained in Example 1 as the air positive electrode under different bending angles is shown. It can be seen that the voltage gap did not change under different bending angles, indicating that HCNT@Co-NC obtained in Example 1 has great development potential in flexible zinc-air batteries.

Claims

1. A method for preparing a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer, characterized in that... The method includes the following steps: Step 1: dissolve chiral surfactant in methanol at room temperature, then add pyrrole and deionized water, stir to form a homogeneous solution, then add pre-cooled to 0-5℃ ammonium persulfate aqueous solution, continue to stir to dissolve, reduce pressure and filter and wash, dry the obtained black solid, to obtain helical structure polypyrrole nanotube; wherein the chiral surfactant is chiral amino acid connected with C 12 ~C 18 carbon chain; Step 2: Disperse the helical polypyrrole nanotubes obtained in Step 1 in methanol, then add a metal salt, stir for 4-7 hours, then centrifuge, wash and dry to obtain helical polypyrrole nanotubes with metal ions modified on the surface; wherein, the metal salt is any one of cobalt nitrate and zinc nitrate; Step 3: Disperse the surface-modified helical polypyrrole nanotubes obtained in Step 2 in methanol, then add a methanol solution of 2-methylimidazole, stir continuously for 10-14 hours, filter, wash and dry to obtain helical polypyrrole coated with a coordination polymer layer. Step 4: The spiral polypyrrole coated with the coordination polymer layer obtained in Step 3 is loaded into a ceramic boat, and then pyrolyzed in a tube furnace filled with Ar at 800-900°C for 2-3 hours to obtain a catalytic material derived from coordination polymer coated twisted polypyrrole nanotubes.

2. The method for preparing the catalytic material derived from twisted polypyrrole nanotubes coated with the coordination polymer according to claim 1, characterized in that: In step 1, the chiral amino acid is selected from any one of D-alanine, L-alanine, D-glutamic acid, L-glutamic acid, D-phenylalanine, L-phenylalanine, D-lysine, and L-lysine.

3. The method for preparing the catalytic material derived from twisted polypyrrole nanotubes coated with the coordination polymer according to claim 1, characterized in that: In step 1, the molar ratio of the chiral surfactant to pyrrole and ammonium persulfate is 1:25–60:25–60, the volume ratio of methanol to deionized water is 1:3–7, and the concentration of the chiral surfactant in methanol is 3.0 × 10⁻⁶. -3 ~8.5×10 -3 mol / L.

4. The method for preparing a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer according to claim 1, characterized in that: In step 2, the mass ratio of the metal salt to the helical polypyrrole nanotubes is 1:0.05 to 0.

3.

5. The method for preparing a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer according to claim 1, characterized in that: In step 3, the molar ratio of the 2-methylimidazole to the metal salt in step 2 is 1:0.05 to 0.

4.

6. The method for preparing a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer according to claim 1, characterized in that: In steps 2 and 3, the drying temperature is 60–80°C and the drying time is 12–24 hours.

7. The method for preparing a catalytic material derived from twisted polypyrrole nanotubes coated with a coordination polymer according to claim 1, characterized in that: In step 4, the pyrolysis heating rate is 2-5℃ / min.

8. The catalytic material derived from the coordination polymer-coated twisted polypyrrole nanotubes prepared by any one of claims 1 to 7.

9. The use of the coordination polymer-coated twisted polypyrrole nanotube-derived catalytic material as described in claim 8 as an air cathode material in the preparation of flexible zinc-air batteries.

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