CN-121484091-B - Cobalt/lanthanum hydroxide heterojunction-loaded porous carbon nanofiber electrocatalyst and preparation method thereof

CN121484091BCN 121484091 BCN121484091 BCN 121484091BCN-121484091-B

Abstract

The application provides a porous carbon nanofiber electrocatalyst for loading cobalt/lanthanum hydroxide heterojunction and a preparation method thereof, wherein the preparation method comprises the steps of adding 4, 4-diaminodiphenyl ether and pyromellitic dianhydride into a solvent, and uniformly mixing to prepare polyamic acid precursor spinning solution; the preparation method comprises the steps of carrying out electrostatic spinning on the prepared polyamic acid precursor spinning solution to obtain polyamic acid nanofiber, immersing the prepared polyamic acid nanofiber in a mixed metal salt solution containing cobalt salt, lanthanum salt and zinc salt to obtain a polyamic acid nanofiber precursor loaded with metal ions, carrying out program heating heat treatment on the prepared polyamic acid nanofiber precursor loaded with metal ions in a protective atmosphere to obtain the porous carbon nanofiber electrocatalyst loaded with cobalt/lanthanum hydroxide heterojunction, wherein the prepared porous carbon nanofiber electrocatalyst loaded with cobalt/lanthanum hydroxide heterojunction has excellent electrochemical oxygen reduction reaction and oxygen precipitation reaction dual-function catalytic activity.

Inventors

DENG NANPING
CHI HAO
KANG WEIMIN

Assignees

天津工业大学

Dates

Publication Date: 20260508
Application Date: 20260109

Claims (8)

1. The preparation method of the porous carbon nanofiber electrocatalyst for loading the cobalt/lanthanum hydroxide heterojunction is characterized by comprising the following steps of: s1, adding 4, 4-diaminodiphenyl ether and pyromellitic dianhydride into a solvent, and uniformly mixing to obtain polyamic acid precursor spinning solution; S2, carrying out electrostatic spinning on the polyamic acid precursor spinning solution prepared in the step S1 to prepare polyamic acid nanofiber; s3, dipping the polyamic acid nanofiber prepared in the step S2 into a mixed metal salt solution containing cobalt salt, lanthanum salt and zinc salt to prepare a polyamic acid nanofiber precursor loaded with metal ions; s4, performing program heating heat treatment on the polyamic acid nanofiber precursor loaded with metal ions and prepared in the step 3 in a protective atmosphere to prepare a porous carbon nanofiber electrocatalyst loaded with cobalt/lanthanum hydroxide heterojunction; The temperature-programmed heat treatment process is to heat to 300 ℃ at 2 ℃ per minute, heat to 600 ℃ at 5 ℃ per minute, heat to 900 ℃ at 3 ℃ per minute and heat to be preserved for 30 minutes; In the step S3, the molar ratio of cobalt element, lanthanum element and zinc element in the mixed metal salt solution containing cobalt salt, lanthanum salt and zinc salt is 1 (1-1.2) (4-6); The total concentration of the mixed metal salt solution in the step S3 is 0.1mol/L to 0.7mol/L.
2. The method for preparing a cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst according to claim 1, wherein the molar ratio of 4, 4-diaminodiphenyl ether to pyromellitic dianhydride in step S1 is (0.98-1.02): 1.
3. The method for preparing a cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst according to claim 1, wherein the solid content of the polyamic acid precursor spinning solution prepared in step S1 is 15wt% to 25wt%.
4. The method for preparing a cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst according to claim 1, wherein the cobalt salt, lanthanum salt, and zinc salt in step S3 are independently selected from acetate, nitrate, or chloride.
5. A cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst prepared by the method of any one of claims 1-4.
6. The cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst according to claim 5, wherein the cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst uses porous carbon nanofibers as a carrier, and cobalt/lanthanum hydroxide heterojunction formed in situ by cobalt nanoparticles and lanthanum hydroxide nanoparticles is supported on the carrier.
7. The cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst of claim 5, wherein the porous carbon nanofiber has an in situ etched porous structure.
8. A metal air cell comprising a cobalt/lanthanum hydroxide heterojunction supported porous carbon nanofiber electrocatalyst prepared by the method of any one of claims 1-4.

Description

Cobalt/lanthanum hydroxide heterojunction-loaded porous carbon nanofiber electrocatalyst and preparation method thereof Technical Field The application relates to the technical field of batteries, in particular to a porous carbon nanofiber electrocatalyst for loading cobalt/lanthanum hydroxide heterojunction and a preparation method thereof. Background With the rapid development of socioeconomic performance, traditional fossil energy sources such as coal, oil and natural gas are facing an increasingly scarce crisis. The non-renewable resources are used on a large scale, and the ecological environment is extremely easy to be damaged in a way of being difficult to reverse. Meanwhile, renewable energy sources such as wind energy, solar energy and the like are required to depend on a matched energy storage system in practical application so as to ensure continuous and stable output of electric energy. Zinc-air batteries have become a significant electrical energy storage technology because of their flat discharge platform, high energy density, environmental friendliness, and low cost. In zinc-air batteries, electrochemical oxygen reduction (ORR) and Oxygen Evolution (OER) reactions are key processes that determine their performance. At present, noble metal materials such as Pt, ru and the like show excellent electrocatalytic activity in ORR and OER, but noble metal resources are scarce and expensive, so that the large-scale application of the noble metal materials in zinc-air batteries is greatly limited. Therefore, the development of the non-noble metal ORR/OER dual-function electrocatalyst with high activity and low cost has become a key direction for promoting the development of the field, and has important research value and wide application prospect. The one-dimensional carbon nanofiber serving as an electrocatalyst carrier has the structural advantages of high length-diameter ratio, large specific surface area, excellent conductivity, low preparation cost and the like. These properties contribute to the rapid conduction of electrons along the fiber axis, however, pure carbon materials themselves have limited catalytic activity for electrochemical oxygen reduction and oxygen evolution reactions, and it is difficult to provide sufficient reactive sites. For this reason, it is generally necessary to incorporate an active component having an electrocatalytic function in its structure to enhance the overall performance. As disclosed in prior art CN117026425B, an electro-catalyst of carbon nanofiber doped with iron-cobalt alloy is prepared by combining electrostatic melt blowing with high-temperature carbonization process, and the method etches a carbon film coated with alloy particles by zinc oxide at high temperature by introducing zinc source, thereby exposing more alloy active sites and improving catalytic performance to a certain extent. However, such a bimetallic alloy-based catalyst still has defects that, on one hand, electrochemical oxygen reduction reaction and oxygen precipitation reaction are two processes with opposite electron transfer directions, a single metal phase catalyst represented by an iron-cobalt alloy has a surface electronic structure which needs to meet the requirement of optimal adsorption of an electrochemical oxygen reduction reaction intermediate and an oxygen precipitation reaction intermediate, which is difficult to be compatible in thermodynamics, so that the improvement of bifunctional catalytic activity is limited, on the other hand, improvement is concentrated on physical exposure of an existing active site by means of pore-forming, etching and the like, and the chemical characteristics of the active site are limited, on the other hand, the accessibility and the utilization rate of the active site of the electrocatalyst are limited, and although the pore-forming technology increases the specific surface area of a carrier, newly generated metal nano particles are extremely easy to be wrapped by amorphous carbon or graphite carbon layers in the high-temperature carbonization process, the carbon encapsulation effect can stabilize the metal particles, but the contact of the active site and the electrolyte is blocked, the actually exposed active interface which can be used for catalysis is far lower than a theoretical value, on the other hand, transition metals such as iron and the like are easy to destroy under the high alkaline and high-potential working conditions, oxidize and grow to cause rapid dissolution, agglomeration and stability of the alloy, and long-term stability are challenging. Therefore, there is a strong need in the art for a dual-function electrocatalyst for non-noble metal electrochemical oxygen reduction and oxygen evolution reactions that combines high activity and low cost. Disclosure of Invention In order to solve the technical problems, the application provides a porous carbon nanofiber electrocatalyst for loading cobalt/lanthanum hydroxide heterojunction