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Catalytic Twist‐Spun Yarns of Nitrogen‐Doped Carbon Nanotubes
Author(s) -
Lepró Xavier,
OvalleRobles Raquel,
Lima Márcio D.,
Elías Ana Laura,
Terrones Mauricio,
Baughman Ray H.
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201102114
Subject(s) - materials science , carbon nanotube , x ray photoelectron spectroscopy , catalysis , annealing (glass) , doping , nitrogen , scanning electron microscope , composite material , nanotube , chemical engineering , nanotechnology , organic chemistry , chemistry , optoelectronics , engineering
The treatment of free‐standing sheets of multiwalled carbon nanotubes (MWNTs) with a NH 3 /He plasma results in self‐supporting sheets of aligned N‐doped MWNTs (CN x ). These CN x sheets can be easily twist spun in the solid state to provide strong CN x yarns that are knottable, weavable, and sewable. The CN x yarns exhibit tunable catalytic activity for electrochemically driven oxygen reduction reactions (ORR), as well as specific capacitances (up to 39 F·g −1 ) that are 2.6 times higher than for the parent MWNTs. Due to a high degree of nanotube alignment, the CN x yarns exhibit specific strengths (451 ± 61 MPa·cm 3 ·g −1 ) that are three times larger than observed for hybrid CN x /MWNT biscrolled yarns containing 70 wt.% CN x in the form of a powder. This difference in mechanical strength arises from substantial differences in yarn morphology, revealed by electron microscopy imaging of yarn cross‐ sections, as well as the absence of a significant strength contribution from CN x nanotubes in the biscrolled yarns. Finally, the chemical nature and abundance of the incorporated nitrogen within the CN x nanotubes is studied as function of plasma exposure and annealing processes using X‐ray photoelectron spectroscopy and correlated with catalytic activity.