Selective synthesis of sub-20 nm carbon nanotubes via carbonate electroreduction in fluoride-based molten carbonates

초록

Carbonate electroreduction in molten salt electrolytes provides a promising pathway for transforming carbonate into high-value carbon nanotubes (CNTs). However, achieving precise size control and uniformity remains a significant obstacle for ensuring the reliability of CNTs in advanced practical applications. Here, we demonstrate that CNTs with average diameters of similar to 11 nm (30 mol% LiF at 550 degrees C) and similar to 16 nm (30 mol% LiF at 500 degrees C) can be selectively synthesized with high Faradaic efficiencies of 73.8% and 82.5%, respectively. Fluoride regulates anodic dissolution behavior, leading to the controlled formation of nanosized catalysts that promote CNT nucleation with smaller diameters. Moreover, it inhibits the lateral growth of CNTs by forming C-F bonds, yielding CNTs with thinner wall thicknesses. The inherent nanosized catalysts and abundant C-F functional groups within the synthesized CNTs serve to effectively enhance the electrochemical kinetics and stability of the material as a Li-ion storage host. This work provides a comprehensive understanding of the CNT synthesis mechanism during carbonate electroreduction in fluoride-based molten carbonate electrolytes.

키워드