Intrinsic Chirality Origination in Carbon Nanotubes.

Elucidating the origin of carbon nanotube chirality is key for realizing their untapped potential. Currently, prevalent theories suggest that catalyst structure originates chirality via an epitaxial relationship. Here we studied chirality abundances of carbon nanotubes grown on floating liquid Ga droplets, which excludes the influence of catalyst features, and compared them with abundances grown on solid Ru nanoparticles.

Pulsed-laser deposited transition-metal carbides for field-emission cathode coatings.

Thin films of transition-metal carbides ZrC, HfC, and TiC were deposited by pulsed-laser deposition under vacuum. The surface chemistry of the films was characterized with ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy in situ. X-ray diffraction was used to characterize the film structure.

Revealing the impact of catalyst phase transition on carbon nanotube growth by in situ Raman spectroscopy.

The physical state of the catalyst and its impact on the growth of single-walled carbon nanotubes (SWNTs) is the subject of a long-standing debate. We addressed it here using in situ Raman spectroscopy to measure Fe and Ni catalyst lifetimes during the growth of individual SWNTs across a wide range of temperatures (500-1400 °C). The temperature dependence of the Fe catalyst lifetimes underwent a sharp increase around 1100 °C due to a solid-to-liquid phase transition.