Advanced Surface Chemistry Analysis of Carbon Nanotube Fibers by X-ray Photoelectron Spectroscopy

Abstract

Carbon nanotube fibers are materials with an exceptional combination of properties, including higher toughness than carbon fibers, electrical conductivity above metals, large specific surface area (250 $\frac{m^2}{g}$) and high electrochemical stability. As such, they are a key component in various multifunctional structures combining augmented mechanical properties with efficient interfacial energy storage/transfer processes. This work presents a thorough XPS study of CNT fibers subjected to different purification and chemical treatments, including spatially-resolved micro XPS synchrotron measurements. The dominant feature is an inherently high degree of $s{p}^2$ conjugation, leading to a strong plasmonic band and a semi-metallic valence band lineshape. This high degree of CNT perfection in terms of longitudinal graphitization helps to explain reported bulk properties including the high electrical and thermal conductivity, and accessible quantum capacitance. There is also presence of organic impurities, mostly heavy carbonaceous molecules formed as by-products during fiber synthesis and which are adsorbed on the CNTs. Sulfur, a promoter used in the CNT growth reaction, is found both in these surface impurities and associated with the Fe catalyst. The observation of strongly-adsorbed surface impurities is consistent with the high ductility of CNT fibers, attributed to interfacial lubricity.

24 pages, 8 figures

References in corpus (4)

• Large-area, all-solid and flexible electric double layer capacitors based on CNT fiber electrodes and polymer electrolytes
• Manganese Dioxide Decoration of Macroscopic Carbon Nanotube Fibers: From High-Performance Liquid-Based to All-Solid-State Supercapacitors
• Gas-phase functionalization of macroscopic carbon nanotube fiber fabrics: reaction control, electrochemical properties and use for flexible supercapacitors
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Cited by in corpus (5)

• Controlled electrochemical functionalization of CNT fibers: structure-chemistry relations and application in current collector-free all-solid supercapacitors
• Macroscopic yarns of FeCl${}_3$-intercalated collapsed carbon nano-tubes with high doping and stability
• Interfacial studies in CNT fibre/TiO${}_2$ photoelectrodes for efficient H${}_2$ production
• Origin of the electrocatalytic activity in carbon nanotube fiber counter-electrodes for solar-energy conversion
• Carbon nanotube synthesis and spinning as macroscopic fibers assisted by the ceramic reactor tube