CN-115995569-B - Inorganic salt assisted derived self-supported Fe-N-C oxygen reduction electrocatalyst and preparation method thereof

CN115995569BCN 115995569 BCN115995569 BCN 115995569BCN-115995569-B

Abstract

The invention discloses an inorganic salt assisted derived self-supported Fe-N-C oxygen reduction electrocatalyst and a preparation method thereof, wherein the electrocatalyst is a random particle and/or sheet aggregate, the content of C element is 82.64-90.64 at%, the content of N element is 2.95-5.95 at%, the content of Fe element is 0.06-0.28 at%, the average mesoporous aperture is 9.7+/-0.2 nm, the most probable aperture is 2.1nm, the specific surface area is 1124+/-5 m 2 g ‑1 , and the self-supported Fe-N-C oxygen reduction catalyst comprises a nitrogen-containing precursor, a nitrogen auxiliary agent, a pore-forming agent and a nitrogen-containing precursor molecular structure regulating agent, wherein the nitrogen-containing precursor comprises polyaniline, the nitrogen-containing precursor molecular structure regulating agent comprises inorganic salt, and the mass ratio of the nitrogen-containing precursor to the nitrogen-containing auxiliary agent is 2:1-20. The electrocatalyst and the preparation method thereof have the characteristics of low-cost and easily-obtained raw materials, simple and controllable process and excellent electrochemical performance.

Inventors

YAN XIANGHUI
ZHOU PENGFEI
YANG JUNCHENG
CHEN DIHAO
MA JIALE
XUE TONG

Assignees

北方民族大学

Dates

Publication Date: 20260505
Application Date: 20230213

Claims (4)

1. An inorganic salt assisted derived self-supported Fe-N-C oxygen reduction electrocatalyst, characterized in that the self-supported Fe-N-C oxygen reduction catalyst is an irregular particle and/or flake aggregate; 82.64 to 90.64at percent of C element, 2.95 to 5.95 at percent of N element, 0.06 to 0.28 at percent of Fe element, 9.7+/-0.2 nm percent of average mesoporous pore diameter, 2.1 nm percent of most probable pore diameter and 1124+/-5 m 2 g -1 percent of specific surface area; the self-supported Fe-N-C oxygen reduction catalyst comprises a nitrogen-containing precursor, a nitrogen-doped auxiliary agent and a pore-forming agent and a molecular structure regulating agent of the nitrogen-containing precursor, wherein the nitrogen-containing precursor is polyaniline, the nitrogen-doped auxiliary agent and the pore-forming agent are melamine, the inorganic salt is one or a composition of more than two of AlCl 3 、NaF、NaCl、NaBr、NaI、KCl、MgCl 2 and/or NH 4 Cl, the molecular structure regulating agent of the nitrogen-containing precursor comprises inorganic salt, and the mass ratio of the nitrogen-containing precursor to the nitrogen-doped auxiliary agent and the pore-forming agent is 2:1-20; The preparation method of the self-supported Fe-N-C oxygen reduction electrocatalyst comprises the following steps: S1, preparing solid powder A, namely adding inorganic salt serving as a molecular structure regulator of a nitrogen-containing precursor into an acidic aqueous solution, adding a monomer of the nitrogen-containing precursor, uniformly dispersing by ultrasonic, dropwise adding an aqueous solution of ammonium persulfate and FeCl 3 ·6H 2 O, continuously stirring, and finally carrying out suction filtration, drying and grinding on the mixed solution to obtain the solid powder A; S2, preparing a catalyst precursor, namely carrying out solid-phase mixing on the A obtained in the step S1 and melamine serving as a nitrogen-doped auxiliary agent and a pore-forming agent to obtain the catalyst precursor; s3, preparing a primary catalyst, namely heating the B obtained in the step S2 to 850-950 ℃ at 10+/-5 ℃ per min under the protection of flowing inert gas, keeping for 1-3 hours, naturally cooling to room temperature, and grinding uniformly to obtain the primary catalyst; s4, acid treatment of the catalyst, namely immersing the primary catalyst obtained in the step 3) in an acid solution with the temperature of 60-80 ℃ and the temperature of 0.5-2M, stirring for 0.5-24 hours, and carrying out suction filtration, washing and drying after the completion of the treatment to obtain a self-supported Fe-N-C catalyst for removing part of iron species; And S5, performing secondary heat treatment on the catalyst, namely heating the self-supported Fe-N-C catalyst obtained in the step S4 to 800-1000 ℃ at 10+/-5 ℃ per minute under the protection of -1 flowing gas in 180-220 mL min, keeping the temperature for 0.5-3 h, and naturally cooling to room temperature to obtain the final self-supported Fe-N-C oxygen reduction catalyst.
2. The method of claim 1, wherein the solid phase mixing is solid phase milling and/or ball milling in step S2.
3. The inorganic salt-assisted derived supported Fe-N-C oxygen reduction electrocatalyst according to claim 1, wherein: in step S3, the flowing inert gas is nitrogen and/or argon.
4. The inorganic salt-assisted derived supported Fe-N-C oxygen reduction electrocatalyst according to claim 1, wherein: in step S5, the flowing gas is nitrogen and/or argon.

Description

Inorganic salt assisted derived self-supported Fe-N-C oxygen reduction electrocatalyst and preparation method thereof Technical Field The invention relates to the technical field of non-noble metal catalysts, in particular to a self-supported Fe-N-C oxygen reduction electrocatalyst derived by assistance of inorganic salts and a preparation method thereof. Background At present, fe-N-C materials have been found to be one of the most promising non-noble metal catalysts for fuel cell cathode ORR in place of noble metal Pt, with activities that are comparable to or even superior to commercial Pt/C catalysts in three-electrode systems to catalyze Oxygen Reduction Reactions (ORR). Nevertheless, further increasing the density of active sites of Fe-N-C catalysts to increase their activity, stability, still present significant challenges. The Fe-N-C material synthesized by using mesoporous silicon as a hard template has remarkable activity and stability on ORR, and the Fe-N-C material created by precisely designing a local coordination environment by using a Metal Organic Framework (MOF) as a carbon nitrogen precursor also has very high ORR activity. The result shows that the Fe-N-C material obtained by the strategy has higher active site density than the Fe-N-C material synthesized by the conventional method, thus showing higher electrocatalytic performance. However, in these methods, there are high raw material costs, such as the case of chinese patent application CN110137518A mainly using self-made mesoporous molecular sieve and chelating agent sodium iron ethylenediamine tetraacetate as raw materials, such as the case of chinese patent application CN113368879a mainly using polydentate chelating agent, and the case of corrosion acid or strong base etching to remove hard templates, and additionally increasing energy consumption, such as the case of chinese patent application CN110137518A which needs to be etched with acid or alkali aqueous ethanol solution in its preparation step 3), such as the case of chinese patent application CN113368879a which needs to be etched with acid or alkali aqueous ethanol solution in its step S3, to obtain the primary catalyst for removing silica microspheres. The defects can greatly increase the production cost of the Fe-N-C material, and the requirements of the low-cost and high-performance Fe-N-C catalyst can not be met. Disclosure of Invention The invention aims to provide a self-supported Fe-N-C oxygen reduction electrocatalyst derived by assistance of inorganic salt and a preparation method thereof, and the self-supported Fe-N-C oxygen reduction electrocatalyst has the characteristics of low-cost and easily available raw materials, simple and controllable process and excellent electrochemical performance. The invention can be realized by the following technical scheme: The invention discloses an inorganic salt assisted derived self-supported Fe-N-C oxygen reduction electrocatalyst, which is a random particle and/or sheet aggregate; 82.64-90.64at.% of C element, 2.95-5.95at.% of N element, 0.06-0.28at.% of Fe element, 9.7+ -0.2 nm of average mesoporous pore diameter, 2.1nm of most probable pore diameter and 1124+ -5 m 2g-1 of specific surface area; The self-supported Fe-N-C oxygen reduction catalyst comprises a nitrogen-containing precursor, a nitrogen-doped auxiliary agent, a pore-forming agent and a nitrogen-containing precursor molecular structure regulating agent, wherein the nitrogen-containing precursor comprises polyaniline, the nitrogen-containing precursor molecular structure regulating agent comprises inorganic salt, and the mass ratio of the nitrogen-containing precursor to the nitrogen-doped auxiliary agent is 2:1-20. Further, the nitrogen-containing precursor is one or a combination of more than two of polyaniline, polypyrrole, polyphthalenediamine and/or polydopamine. Further, the nitrogen-doped auxiliary agent and pore-forming agent are one or a combination of more than two of melamine, cyanamide, urea and/or ammonium chloride. Further, the inorganic salt is one or more than two of AlCl 3、NaF、NaCl、NaBr、NaI、KCl、MgCl2 and/or NH 4 Cl. In another aspect, the present invention provides a method for preparing a supported Fe-N-C oxygen reduction electrocatalyst derived from the above inorganic salt, comprising the steps of: S1, preparing solid powder A, namely adding inorganic salt serving as a molecular structure regulator of a nitrogen-containing precursor into an acidic aqueous solution, adding a monomer of the nitrogen-containing precursor, uniformly dispersing by ultrasonic, dropwise adding an aqueous solution of ammonium persulfate and FeCl 3·6H2 O, continuously stirring, and finally carrying out suction filtration, drying and grinding on the mixed solution to obtain solid powder A; s2, preparing a catalyst precursor, namely carrying out solid-phase mixing on the A obtained in the step S1 and melamine serving as a nitrogen-doped auxiliary agent and a pore-forming a