Fe3C@C/CNT Hybrids Derived from Catalytic Pyrolysis of Lignite: Electrocatalysts for OER

Using lignite as the raw material to prepare a new OERcatalyst,and thus to make high-value use of lignite and to meet the researchand development needs for new energy materials at the same time, anovel Fe/Fe3C active species has been reported as a promisingcatalyst to replace precious metals. In this study, we developed afacile method for the preparation of Fe3C@C/CNT hybridmaterials by catalytic pyrolysis of lignite using KOH and FeCO3. The structural characteristic of Fe3C@C/CNT hybridmaterials is that Fe3C nanoparticles are encapsulated incarbon layers and carbon nanotubes, forming a special core-shellstructure. The prepared materials have good graphitization and a largespecific surface area (957 m(2) g(-1)). Wediscussed the effects of KOH, FeCO3, and melamine in thecatalytic pyrolysis of lignite to produce Fe3C@C/CNT materials:(1) Lignite can be catalyzed by KOH to generate carbon nanotubes andporous structures. (2) The transformation of carbon matrix to graphiticcarbon is catalyzed and the Fe source for Fe3C is providedby FeCO3. (3) The aggregation of Fe into large and irregularFe nanoparticles is inhibited by melamine, which facilitates the generationof Fe3C. When the Fe3C@C/CNT hybrid is usedas an OER catalyst, the OER overpotential is only 407 mV at a currentdensity of 10 mA cm(-2) in an alkaline electrolyte,which has great application potential. This work is conducive to improvingthe economic benefits of lignite and provides a new idea for the highvalue-added utilization of lignite.

Automated summary

In this study, a new OER catalyst was prepared using lignite as the raw material, which not only makes high-value use of lignite, but also meets the research and development needs for new energy materials. A novel Fe/Fe3C active species was reported as a promising catalyst to replace precious metals. By catalytic pyrolysis of lignite using KOH and FeCO3, Fe3C@C/CNT hybrid materials with a special core-shell structure were prepared, and it showed great application potential as an OER catalyst. This work provides a new idea for the high-value-added utilization of lignite and contributes to improving its economic benefits.