A high-performance nickel / carbon multi-dimensional nano-assembly structure electrocatalyst, a preparation method and application thereof

Abstract

The application discloses a high-performance nickel / carbon multi-dimensional nano-assembly structure electrocatalyst and a preparation method and application thereof. A nickel / carbon multi-dimensional nano-assembly structure electrocatalyst with one-dimensional carbon nanotubes and two-dimensional carbon sheets loaded with zero-dimensional nickel nanoparticles is prepared by mixing nickel salt and a biological organic ligand as a precursor and through simple one-step pyrolysis, taking the biological organic ligand as a carbon source. The biological organic ligand derived carbon material is converted into carbon sheets by using the thermal decomposition of the nickel salt, and meanwhile, the metallic nickel generated by the carbon thermal reduction catalyzes the carbon material to generate carbon nanotubes at high temperature, so as to construct the unique nickel / carbon multi-dimensional nano-assembly structure. The unique multi-dimensional structure has a large specific surface area and a large number of exposed active sites, and is beneficial to the improvement of the catalyst performance.

Description

Technical Field

[0001] This invention belongs to the field of energy, specifically relating to a high-performance nickel / carbon multidimensional nano-assembled electrocatalyst, its preparation method, and its application. Background Technology

[0002] In recent years, zinc-air batteries have attracted much attention from researchers as a promising clean energy device, and their air cathode catalysts are key materials affecting battery activity, lifespan, and cost. Carbon-based materials are frequently used as catalysts for various catalytic reactions due to their low cost, wide availability, and high conductivity. However, traditional carbon-based non-precious metal catalysts still suffer from low metal site density and uneven distribution, which makes their performance in the oxygen reduction / oxygen evolution reaction (ORR / OER) slightly inferior to commercially available precious metal catalysts. Therefore, the research focus of non-precious metal catalysts for zinc-air battery cathodes is to design and construct rich active structures and improve their accessibility in electrochemical reactions.

[0003] Recent research indicates that the catalytic activity of electrocatalysts can be effectively improved by rationally designing and controllably synthesizing special multidimensional nano-assemblies to achieve high exposure of active sites. For example, assembling alloy nanoparticles, nitrogen-doped carbon nanotubes, and graphene using multi-scale design principles can be used for efficient oxygen reduction reactions, outperforming commercial Pt / C catalysts. The multiple active sites and hierarchical nano-carbon matrix in multidimensional nano-assemblies not only improve the utilization rate of active sites but also enhance electron transfer and mass exchange, jointly promoting the ORR process. This demonstrates that multidimensional nano-assemblies of carbon materials composited with transition metals possess enhanced electrocatalytic performance. Therefore, developing controllable preparation strategies for multidimensional nano-assemblies with transition metal embedded in carbon matrices, leveraging the advantages of structural units and fully utilizing active sites, is a feasible strategy for improving electrocatalytic performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-performance nickel / carbon multidimensional nano-assembled electrocatalyst, its preparation method, and its application.

[0005] This invention provides a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst, wherein the structure of the electrocatalyst is one-dimensional carbon nanotubes uniformly grown on a two-dimensional carbon sheet, and zero-dimensional nickel nanoparticles are loaded on it.

[0006] This invention provides a method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst, wherein the precursor is heated in an argon atmosphere and the high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst is directly generated by one-step pyrolysis.

[0007] Furthermore, the specific steps include:

[0008] a. Dissolve the biological organic ligand in pure water at a certain temperature by heating, add nickel salt, continue heating until the solution evaporates to dryness, collect the remaining solid and grind it to obtain precursor powder;

[0009] b. The precursor powder is placed in a tube furnace for pyrolysis, heated to the target temperature at a certain heating rate in an argon atmosphere and held for a certain time to obtain the high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst.

[0010] Furthermore, the biological organic ligand is one of adenine, guanine, cytosine, or thymine, used in an amount of 0.06-1.00 g, and dissolved at a temperature of 50-120 °C.

[0011] Furthermore, the nickel salt is one of nickel chloride, nickel acetate, nickel nitrate, or nickel sulfate, and the amount used is 0.1-5.0 mmol.

[0012] Furthermore, the heating rate during pyrolysis is 1-10 °C. The target temperature is 500-900 °C, and the holding time is 1-5 h.

[0013] This invention also provides applications of the above-mentioned high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst.

[0014] Beneficial effects:

[0015] This invention uses a mixture of nickel salt and bio-organic ligands as a precursor to prepare a nickel / carbon multidimensional nano-assembled electrocatalyst with one-dimensional carbon nanotubes and two-dimensional carbon sheets supporting zero-dimensional nickel nanoparticles via one-step pyrolysis. The method is simple and the catalyst structure is novel. The structure of the electrocatalyst can be effectively controlled by changing the amount of nickel salt added, and the method is controllable. This unique multidimensional structure has a large specific surface area and a large number of exposed active sites, which is beneficial to the improvement of catalyst performance and has good application results in zinc-air batteries. Attached Figure Description

[0016] Figure 1 Schematic diagram of the preparation process of nickel / carbon multidimensional nano-assembled electrocatalyst.

[0017] Figure 2 SEM image of a nickel / carbon multidimensional nano-assembled electrocatalyst.

[0018] Figure 3 XRD pattern of nickel / carbon multidimensional nano-assembled electrocatalyst.

[0019] Figure 4(a) Schematic diagram of a zinc-air battery; (b) Open-circuit voltage (OCV) diagram of a zinc-air battery based on Ni@NC and Pt / C catalysts, with an inset showing a photograph of two Ni@NC-catalyzed zinc-air batteries with LEDs lit; (c) Discharge polarization curves and power density curves of a zinc-air battery catalyzed by Ni@NC and Pt / C; (d) Discharge curves of a zinc-air battery catalyzed by Ni@NC and Pt / C. Detailed Implementation

[0020] Example 1

[0021] A method for preparing a high-performance nickel / carbon multidimensional nanostructured electrocatalyst includes the following steps: a) Dissolving a bio-organic ligand in pure water at a certain temperature, adding a nickel salt, and continuing heating until the solution evaporates to dryness. Collecting the remaining solid and grinding it yields a precursor powder; b) Pyrolyzing the precursor powder in a tube furnace under an argon atmosphere at a specific heating rate to a target temperature and holding at that temperature for a certain time to obtain the high-performance nickel / carbon multidimensional nanostructured electrocatalyst. The bio-organic ligand is guanine, used in an amount of 0.4 g, with a dissolution temperature of 80 °C; the nickel salt is nickel acetate, used in an amount of 0.5 mmol; and the heating rate during pyrolysis is 1 °C. The target temperature is 600 °C, and the holding time is 2 hours.

[0022] Example 2

[0023] A method for preparing a high-performance nickel / carbon multidimensional nano-assembled electrocatalyst includes the following steps: a) Dissolving a bio-organic ligand in pure water at a certain temperature, adding a nickel salt, and continuing heating until the solution evaporates to dryness. The remaining solid is collected and ground to obtain a precursor powder; b) Pyrolyzing the precursor powder in a tube furnace under an argon atmosphere at a specific heating rate to a target temperature and holding for a certain time to obtain the high-performance nickel / carbon multidimensional nano-assembled electrocatalyst. The bio-organic ligand is adenine, used in an amount of 0.6 g, with a dissolution temperature of 90 °C; the nickel salt is nickel nitrate, used in an amount of 2 mmol; and the heating rate during pyrolysis is 3 °C. The target temperature is 700 °C, and the holding time is 3 hours.

[0024] Example 3

[0025] A method for preparing a high-performance nickel / carbon multidimensional nano-assembled electrocatalyst includes the following steps: a) Dissolving a bio-organic ligand in pure water at a certain temperature, adding a nickel salt, and continuing heating until the solution evaporates to dryness. The remaining solid is collected and ground to obtain a precursor powder; b) Pyrolyzing the precursor powder in a tube furnace under an argon atmosphere at a specific heating rate to a target temperature and holding for a certain time to obtain the high-performance nickel / carbon multidimensional nano-assembled electrocatalyst. The bio-organic ligand is guanine, used in an amount of 0.5 g, with a dissolution temperature of 90 °C; the nickel salt is nickel nitrate, used in an amount of 3 mmol; and the heating rate during pyrolysis is 2 °C. The target temperature is 800 °C, and the holding time is 2 hours.

[0026] Example 4

[0027] A method for preparing a high-performance nickel / carbon multidimensional nano-assembled electrocatalyst includes the following steps: a) Dissolving a bio-organic ligand in pure water at a certain temperature, adding a nickel salt, and continuing heating until the solution evaporates to dryness. The remaining solid is collected and ground to obtain a precursor powder; b) Pyrolyzing the precursor powder in a tube furnace under an argon atmosphere at a specific heating rate to a target temperature and holding for a certain time to obtain the high-performance nickel / carbon multidimensional nano-assembled electrocatalyst. The bio-organic ligand is cytosine, used in an amount of 0.8 g, with a dissolution temperature of 100 °C; the nickel salt is nickel acetate, used in an amount of 2 mmol; and the heating rate during pyrolysis is 3 °C. The target temperature is 700 °C, and the holding time is 2 hours.

[0028] Application test of high-performance nickel / carbon multidimensional nano-assembled electrocatalyst in zinc-air battery: 4 mg of the catalyst prepared in Example 2 was ultrasonically treated for 40 minutes in 970 µL of anhydrous ethanol and 30 µL of Nafion (5 wt%) solution to obtain a uniformly suspended catalyst ink, which was then sprayed onto carbon paper (0.8... As an air cathode, the catalyst loading is approximately 1.0 mg. In contrast, a commercially available Pt / C (20 wt%) catalyst was used to fabricate the air cathode for a zinc-air battery using the same method and loading. A zinc sheet (0.5 mm thick) was polished to remove oxides from its surface and used as the anode, with a 6.0 M KOH solution as the electrolyte for discharge testing.

[0029] from Figure 4(b) It can be seen that the zinc-air cell with nickel / carbon multidimensional nano-assembled structure electrocatalyst (Ni@NC) as air cathode catalyst has a stable open-circuit voltage of 1.44 V, which is close to that of the zinc-air cell using commercial Pt / C catalysis (1.48 V), and the inset shows a 2.2 V red light-emitting diode (LED) that can be powered by two Ni@NC-based zinc-air cells in series. Figure 4 (c) shows that at a current density of 198.1 mA At that time, the zinc-air cell catalyzed by Ni@NC exhibited 118.1 mW. Its maximum power density is close to that of a zinc-air battery catalyzed by Pt / C (124.5 mW). ). Figure 4 The two curves in (d) represent the zinc-air cells catalyzed by Ni@NC and Pt / C, respectively, at 10 mA. The galvanostatic discharge curve at current density shows that the Ni@NC-based zinc-air battery has a capacity of 778.1 mAh. Specific capacity and 925.9 Wh The energy density is comparable to that of a Pt / C-based zinc-air battery (766.2 mAh). 957.8 Wh The results are close. In summary, the above analysis indicates that the nickel / carbon catalyst Ni@NC with its multidimensional nano-assembly structure exhibits good ORR catalytic activity and has certain application potential in primary zinc-air batteries.

Claims

1. A high-performance nickel / carbon multidimensional nano-assembled electrocatalyst, characterized in that, The electrocatalyst has a structure in which one-dimensional carbon nanotubes are uniformly grown on a two-dimensional carbon sheet, and zero-dimensional nickel nanoparticles are loaded on it.

2. The method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst according to claim 1, characterized in that, In an argon atmosphere, the precursor is heated and directly generated through one-step pyrolysis to produce the high-performance nickel / carbon multidimensional nano-assembled electrocatalyst.

3. The method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst according to claim 2, characterized in that, Specifically, the following steps are included: a. Dissolve the biological organic ligand in pure water at a certain temperature by heating, add nickel salt, continue heating until the solution evaporates to dryness, collect the remaining solid and grind it to obtain precursor powder; b. The precursor powder is placed in a tube furnace for pyrolysis, heated to the target temperature at a certain heating rate in an argon atmosphere and held for a certain time to obtain the high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst.

4. The method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst according to claim 3, characterized in that, The biological organic ligand is one of adenine, guanine, cytosine, or thymine, used in an amount of 0.06-1.00 g, and dissolved at a temperature of 50-120 °C.

5. The method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst according to claim 3, characterized in that, The nickel salt is one of nickel chloride, nickel acetate, nickel nitrate, or nickel sulfate, and is used in an amount of 0.1-5.0 mmol.

6. The method for preparing a high-performance nickel / carbon multidimensional nano-assembled structure electrocatalyst according to claim 3, characterized in that, The heating rate during pyrolysis is 1-10 °C. The target temperature is 500-900 °C, and the holding time is 1-5 h.

7. An application of the high-performance nickel / carbon multidimensional nano-assembled electrocatalyst according to claim 1.

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