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CN-122025673-A - Rod-shaped cobalt manganese molybdate electrode catalyst and preparation method and application thereof

CN122025673ACN 122025673 ACN122025673 ACN 122025673ACN-122025673-A

Abstract

The invention relates to a rod-shaped cobalt manganese molybdate electrode catalyst and a preparation method and application thereof, and the preparation method comprises the following steps of (S1) dissolving cobalt salt, manganese salt and an organic ligand in a molar ratio of 1 (0.9-1.1) (1-2) in water, and carrying out a coordination reaction to obtain a solution A, wherein the molar amounts of the cobalt salt and the manganese salt are respectively calculated by Co and Mn, the organic ligand is 2-phosphonobutane-1, 2, 4-tricarboxylic acid and/or aminotrimethylene phosphonic acid, (S2) dissolving alkali metal molybdate in water to obtain a solution B, adding the solution B into the solution A, carrying out a coprecipitation reaction to obtain precursor powder, and calcining the precursor powder under an oxygen-containing atmosphere to obtain the rod-shaped cobalt manganese molybdate electrode catalyst. According to the invention, two metal elements of cobalt and manganese are simultaneously introduced into a molybdate system, and Co 2+ and Mn 2+ are pre-complexed by an organic ligand, so that the rod-shaped cobalt-manganese molybdate electrode catalyst with uniformly distributed atomic scale is finally prepared, and the catalyst shows excellent ORR/OER double-function catalytic activity.

Inventors

  • SUN GENBAN
  • XU JINGSHEN
  • LI HUIFENG
  • Yuan Mengwei

Assignees

  • 北京师范大学

Dates

Publication Date
20260512
Application Date
20260130

Claims (10)

  1. 1. The preparation method of the rod-shaped cobalt manganese molybdate electrode catalyst is characterized by comprising the following steps of: (S1) cobalt salt, manganese salt and an organic ligand are dissolved in water according to a molar ratio of (0.9-1.1) (1-2) together, a coordination reaction is carried out under a stirring state, so as to form a solution A, the molar amount of the cobalt salt is calculated by Co, the molar amount of the manganese salt is calculated by Mn, and the organic ligand is 2-phosphonobutane-1, 2, 4-tricarboxylic acid (PBTCA) and/or amino trimethylene phosphonic Acid (ATMP); (S2) dissolving alkali metal molybdate in water to form a solution B, adding the solution B into the solution A, performing coprecipitation reaction under stirring, separating, washing and drying after the reaction is finished to obtain precursor powder; (S3) calcining the precursor powder in an oxygen-containing atmosphere to obtain the rod-shaped cobalt manganese molybdate electrode catalyst.
  2. 2. The preparation method according to claim 1, wherein in the step (S1), the molar ratio of cobalt salt, manganese salt and organic ligand is 1 (0.9-1.1): 1.5-2, more preferably 1 (0.95-1.05): 1.5-2.
  3. 3. The method according to claim 1, wherein in the step (S1), the cobalt salt is at least one selected from cobalt chloride (CoCl 2 ), cobalt sulfate (CoSO 4 ), cobalt nitrate (Co (NO 3 ) 2 ) and hydrates thereof, the manganese salt is at least one selected from manganese chloride (MnCl 2 ), manganese nitrate (Mn (NO 3 ) 2 ), manganese sulfate (MnSO 4 ) and hydrates thereof, and the total concentration of Co ions and Mn ions in the solution a is 0.2 to 0.4mol/L.
  4. 4. The method according to claim 1, wherein in the step (S1), the condition of the coordination reaction is that the pH is 2.0 to 5.0 and the reaction is carried out at 20 to 40 ℃ for 0.5 to 2 hours.
  5. 5. The method according to claim 1, wherein in the step (S2), the ratio of the solution A to the solution B satisfies the molar ratio of (Co+Mn): mo of 1:1.05 to 1.2.
  6. 6. The preparation method of claim 1, wherein in the step (S2), the alkali metal molybdate is at least one selected from sodium molybdate and potassium molybdate or a hydrate thereof, and the concentration of MoO 4 2- in the solution B is 0.1-0.3 mol/L.
  7. 7. The preparation method according to claim 1, wherein in the step (S2), the temperature of the coprecipitation reaction is 30-50 ℃, preferably 40-50 ℃, the time of the coprecipitation reaction is 4-6 hours, the separation is centrifugal separation, the washing is deionized water washing for 2-4 times, and the drying is 60-80 ℃ drying for 6-12 hours.
  8. 8. The method according to claim 1, wherein in (S3), the calcination treatment is performed at a temperature of 400 to 600 ℃ for 3 to 5 hours, and the oxygen-containing atmosphere is air and/or oxygen.
  9. 9. The rod-shaped cobalt manganese molybdate electrode catalyst prepared by the preparation method according to any one of claims 1-8, which is characterized in that the catalyst is of a one-dimensional rod-shaped structure, the diameter of a rod body is 100-200 nm, and the length of the rod body is 0.5-5 μm.
  10. 10. Use of a rod-shaped cobalt manganese molybdate electrode catalyst prepared by the preparation method of any of claims 1 to 8 as a positive electrode catalyst in a lithium-air battery.

Description

Rod-shaped cobalt manganese molybdate electrode catalyst and preparation method and application thereof Technical Field The invention belongs to the technical field of electrocatalysis, and particularly relates to a rod-shaped cobalt manganese molybdate electrode catalyst, and a preparation method and application thereof. Background Under the urgent need of global energy structure to green and low-carbon transformation, the development of high-energy-density and high-efficiency energy storage and conversion technology is of great importance. lithium-Air Batteries (Lithium-Air Batteries, LABs) are open conversion Batteries using oxygen in the Air as the positive electrode active material, and energy storage and conversion are realized based on the generation and decomposition of Li 2O2, and the theoretical energy density (about 3500 Wh/kg) of the Air is higher because of the external Air, so the lithium-Air Batteries are regarded as a potential energy storage system of the next generation. However, commercialization of lithium-air batteries is limited by slow Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) kinetics on the positive electrode side, resulting in high charge-discharge overpotential, low energy conversion efficiency, and aggravation of corrosion of the positive electrode material and decomposition of the electrolyte, thereby severely shortening the cycle life of the battery. Therefore, the development of efficient and stable dual-function (ORR/OER) positive electrode catalysts is a key to breaking through the technical bottlenecks of lithium-air batteries. Transition metal oxides (transition metal oxides, TMOs) and derivatives thereof are becoming research hot spots for replacing noble metal catalysts (such as platinum, ruthenium, etc.) due to the advantages of low cost, abundant reserves, adjustable structure, etc. Wherein, the transition metal molybdate has simple synthesis and stable structure, and has application prospect in the field of electrocatalysis. However, the conventional monometal molybdate catalyst has a single catalytic active site, and it is difficult to efficiently promote two distinct reaction processes of ORR and OER at the same time. In the running process of the battery, the generation and decomposition kinetics of a discharge product (such as Li 2O2) at the positive electrode side are unbalanced, a series of side reactions such as electrode passivation, electrolyte decomposition and positive electrode structure decay are aggravated, and the cycle life and the practical performance of the battery are severely restricted. To overcome the above drawbacks, researchers have attempted to develop multi-metal molybdate catalysts to enhance ORR/OER bifunctional catalytic activity using synergistic effects between different metals. However, when the conventional coprecipitation method is used for preparing the polymetallic molybdate, different metal ions are easy to cause uneven components of a product due to the difference of precipitation rates, the uniform distribution of components on an atomic scale is difficult to realize, and the morphology defects are many, so that the promotion of the catalytic activity and the stability is limited. CN117568849A discloses a rod-shaped high-entropy metal molybdate catalyst, a preparation method and application thereof, and the invention utilizes MoO 3 as a precursor to prepare a target catalyst through one-step hydrothermal reaction, wherein the active components of the prepared high-entropy metal molybdate catalyst comprise molybdates of four transition metals (any four of Ni, co, fe, cu, zn, mn), have good conductivity and excellent physicochemical stability, and have good catalytic activity for oxygen evolution reaction as an electrocatalyst, and can effectively replace noble metal catalysts such as RuO 2, irO 2 and the like. However, in the invention, a plurality of metal ions are subjected to one-step hydrothermal reaction in a hydrothermal system, so that the truly uniform distribution of atomic scale is difficult to ensure, and the prepared catalyst only relates to the Oxygen Evolution Reaction (OER) activity and does not relate to the catalytic performance of the Oxygen Reduction Reaction (ORR). Therefore, there is a need to develop a novel molybdate catalyst which can overcome the defects of the conventional coprecipitation method, realize uniform distribution of metal atomic levels, has high-efficiency ORR/OER dual-function catalytic capability and excellent stability, and can significantly improve the comprehensive electrochemical performance of a lithium-air battery. Disclosure of Invention Aiming at the problems of uneven component distribution, uncontrollable morphology, poor ORR/OER dual-function catalytic activity and insufficient stability of the conventional coprecipitation method for preparing the multi-metal molybdate catalyst, the invention provides a rod-shaped cobalt-manganese molybdate electrode cat