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CN-116555821-B - Nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with parallel array structure and preparation method and application thereof

CN116555821BCN 116555821 BCN116555821 BCN 116555821BCN-116555821-B

Abstract

The invention discloses a nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with a parallel array structure and a preparation method thereof, and belongs to the technical field of energy materials. Firstly, preparing Ni-Co-ZIF crystals with uniform particle size, then adding the Ni-Co-ZIF crystals into polyvinylpyrrolidone spinning solution, and finally preparing the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst with a parallel array structure through micro-flow spinning and high-temperature carbonization. The composite catalyst is a micron-sized fiber membrane and consists of a carbon fiber matrix with a porous structure enriched on the surface and nickel-cobalt-nitrogen co-doped carbon, wherein the nickel-cobalt-nitrogen co-doped carbon is uniformly embedded on the carbon fiber. The material has higher electrocatalytic activity in the oxygen precipitation reaction in alkaline medium, and the performance of the material is superior to that of commercial RuO 2 .

Inventors

  • ZHAO YIGE
  • LI TING
  • ZHANG PENG
  • WANG QING
  • ZHAO MENGYAO
  • SHAO GUOSHENG

Assignees

  • 郑州大学

Dates

Publication Date
20260508
Application Date
20230525

Claims (8)

  1. 1. The preparation method of the nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure comprises the following steps: (1) The preparation of Ni-Co-ZIF crystals comprises dissolving Co (CH 3 COO) 2 ·4H 2 O and Ni (CH 3 COO) 2 ·4H 2 O in ethanol to obtain ethanol solution of Co (CH 3 COO) 2 ·4H 2 O/Ni(CH 3 COO) 2 ·4H 2 O; 2-methylimidazole in ethanol to obtain ethanol solution of 2-methylimidazole; mixing ethanol solution of Co (CH 3 COO) 2 ·4H 2 O /Ni(CH 3 COO) 2 ·4H 2 O with ethanol solution of 2-methylimidazole), stirring, oil bath, centrifuging, cleaning, and vacuum drying to obtain Ni-Co-ZIF crystals; (2) Dissolving a small amount of PVP in DMF solution, adding the Ni-Co-ZIF crystal prepared in the step (1), uniformly dispersing by ultrasonic, adding a proper amount of PVP again and stirring to obtain uniformly dispersed spinning solution, and carrying out micro-flow spinning on the spinning solution to obtain the Ni-Co-ZIF/PVP fiber precursor; (3) And (3) preparing the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst, namely placing the Ni-Co-ZIF/PVP fiber precursor obtained in the step (2) in a muffle furnace for pre-oxidation, and then carbonizing at high temperature in a tubular furnace in an argon atmosphere to obtain the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst with a parallel array structure.
  2. 2. The preparation method of the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure according to claim 1, wherein in the step (1), the stirring time is 1-6 hours, the oil bath temperature is 60-80 ℃, the oil bath time is 5-8 hours, the cleaning reagent is absolute ethyl alcohol and DMF, and the mass ratio of Co (CH 3 COO) 2 ·4H 2 O to Ni (CH 3 COO) 2 ·4H 2 O) is (1:2) - (2:1).
  3. 3. The method for preparing the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure according to claim 1, wherein the molar ratio of cobalt acetate tetrahydrate to nickel acetate tetrahydrate is (1:2) - (2:1), and the ratio of the amount of Co (CH 3 COO) 2 ·4H 2 O to the amount of Ni (CH 3 COO) 2 ·4H 2 O) to the amount of 2-methylimidazole is 3:8.
  4. 4. The preparation method of the nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure is characterized in that in the step (2), a microfluidic spinning machine is adopted to carry out microfluidic spinning on spinning liquid, the proper needle type is selected, the proper temperature and humidity environment factors are regulated through a temperature and humidity control system, proper rotating speed, pushing speed and stepping speed parameter values are set, the spinning liquid is injected into an injector, the microfluidic spinning machine is utilized to carry out microfluidic spinning, the microfluidic spinning machine is composed of a microfluidic pump, a spinning receiver, a temperature and humidity control system, a motor and a workbench, the temperature and humidity control system parameters are 20-40 ℃, the humidity is 10-50%, the microfluidic pump parameters are the needle pushing speed of 0.02-0.08 mL/h, the needle type is 20-24, the rotating speed of the receiver motor is 100-800r/min, the receiving distance between the needle and the receiver is 1-10 mm, and the stepping motor frequency is 1000-300 Hz.
  5. 5. The preparation method of the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure according to claim 1, wherein in the step (2), the total mass ratio of Ni-Co-ZIF to PVP is 1:5-2:1, the mass of PVP added for the first time is 10-30% of the total mass of PVP, every 1g of PVP in the spinning solution needs to be dissolved in 3-5 mL of DMF, and the ultrasonic time is 0.5-5 h.
  6. 6. The method for preparing the nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure according to claim 1, wherein in the step (3), the pre-oxidation process is performed by raising the temperature to 120-180 ℃ at a temperature raising rate of 1-2 ℃ per minute, preserving heat for 1-5 hours, raising the temperature to 220-280 ℃ at a temperature raising rate of 1-3 ℃ per minute, preserving heat for 1-5 hours, the high-temperature carbonization specific process is performed by raising the temperature to 700-1000 ℃ at a temperature raising rate of 1-10 ℃ per minute, preserving heat for 1-5 hours, and the inert gas atmosphere in the tubular furnace is high-purity argon, high-purity nitrogen or other high-purity inert gases.
  7. 7. The nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure, which is prepared by the preparation method of any one of claims 1 to 6, is characterized in that the composite electrocatalyst is a micron-sized fiber composed of a carbon fiber matrix with a porous structure and nickel-cobalt-nitrogen co-doped carbon, wherein the nickel-cobalt-nitrogen co-doped carbon is uniformly embedded on the carbon fiber, the diameter of the nickel-cobalt-nitrogen co-doped carbon is 0.8-1.8 mu m, and the diameter of the carbon fiber is 0.8-2 mu m.
  8. 8. The use of the nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with parallel array structure of claim 7 in oxygen precipitation reaction in alkaline medium.

Description

Nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with parallel array structure and preparation method and application thereof Technical Field The invention relates to the technical field of energy materials, in particular to a nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with a parallel array structure and a preparation method thereof. Background The global energy shortage and the environmental pollution problem are increasingly aggravated, and the society has attracted very extensive attention, and in order to meet the ever-increasing energy demands of people, it is particularly important to seek sustainable, clean and efficient new energy production modes. Electrolyzed water is considered as one of the most potential methods for renewable energy production, storage and use in the future as an efficient, pollution-free sustainable hydrogen generation pathway. However, the anodic oxygen precipitation reaction kinetics process is slow, the reaction barrier is large, so that the overpotential is far higher than the theoretical decomposition voltage of water, and therefore, the development of an efficient oxygen precipitation electrocatalyst is urgent. The most effective oxygen evolution reaction catalysts at present are the noble metal catalysts IrO 2 and RuO 2, but their large-scale commercial application is severely hampered by the problems of scarcity, high cost, and poor electrochemical stability. In recent years, transition metal-based electrocatalysts are considered as a new generation of high-performance oxygen evolution electrocatalytic materials because of their low cost and high intrinsic activity. The zeolite imidazole ester skeleton structure material (ZIFs) containing rich carbon-nitrogen ligand and high-content transition metal ions can be converted into a nitrogen-doped transition metal-based carbon material after high-temperature pyrolysis. The carbon material has a unique hierarchical porous structure, and can increase the specific surface area of the material, thereby improving the electrocatalytic activity of the material. However, pure ZIFs derivative materials still have the problems of poor conductivity, poor stability, low mass transfer rate in the electrochemical reaction process and the like. Carbon fibers with unique one-dimensional structures are known to have the advantages of high conductivity and high stability, and are often used as composites with other materials for wide application in the catalytic field. Therefore, the composite of the ZIFs derivative material and the carbon fiber can greatly enhance the conductivity of the material, and the highly graphitized carbon fiber structure can effectively inhibit the problem of metal particle shedding in the catalytic reaction, so that the catalytic stability of the material is improved. The invention aims to provide a nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with high activity and a preparation method thereof. The material is made into a parallel array structure, so that the directional transfer of ions and charges can be promoted, the mass transfer speed of the composite catalyst can be improved, the electrolyte permeation and the release of gas after reaction can be promoted, and the oxygen precipitation electrocatalytic performance can be further improved. Therefore, the invention provides a method for preparing the nickel-cobalt-nitrogen Co-doped carbon/carbon fiber composite material with a parallel array structure based on a micro-flow spinning technology by compounding Ni-Co-ZIF and PVP fibers. The composite catalyst exhibits electrocatalytic performance in oxygen evolution reactions exceeding commercial ruthenium oxide. Disclosure of Invention In order to achieve the above object, the present invention provides the following solutions: the preparation method of the nickel-cobalt-nitrogen co-doped carbon/carbon fiber composite electrocatalyst with the parallel array structure comprises the following steps: (1) The preparation method of the Ni-Co-ZIF crystal comprises the steps of dissolving cobalt acetate tetrahydrate (Co (CH 3COO)2·4H2 O) and nickel acetate tetrahydrate (Ni (CH 3COO)2·4H2 O)) in ethanol to obtain ethanol solution of Co (CH 3COO)2·4H2O /Ni(CH3COO)2·4H2 O), dissolving dimethyl imidazole (2-MIM) in ethanol to obtain ethanol solution of 2-MIM, mixing the ethanol solution of Co (CH 3COO)2·4H2O /Ni(CH3COO)2·4H2 O) and the ethanol solution of 2-MIM, stirring, oil bath, centrifuging, cleaning and vacuum drying to obtain the Ni-Co-ZIF crystal. (2) The preparation method of the Ni-Co-ZIF/PVP fiber precursor comprises the steps of dissolving a small amount of PVP in N, N-Dimethylformamide (DMF) solution, adding the Ni-Co-ZIF crystal prepared in the step (1), uniformly dispersing by ultrasonic, adding a proper amount of PVP again and stirring to obtain a uniformly dispersed spinning solution, and carrying out micro-flow