Water-soluble full-length single-wall carbon nanotube polyelectrolytes: Preparation and characterization

HiPco single-wall carbon nanotubes (SWNTs) have been noncovalently modified with ionic pyrene and naphthalene derivatives to prepare water-soluble SWNT polyelectrolytes (SWNT-PEs), which are analogous to polyanions and polycations. The modified nanotubes have been characterized with UV-vis-NIR, fluorescence, Raman and X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The nanotube-adsorbate interactions consist of π-π stacking interactions between the aromatic core of the adsorbate and the nanotube surface and specific contributions because of the substituents. The interaction between nanotubes and adsorbates also involves charge transfer from adsorbates to SWNTs, and with naphthalene sulfonates the role of a free amino group was important. The ionic surface charge density of the modified SWNTs is constant and probably controlled by electrostatic repulsion between like charges. The linear ionic charge density of the modified SWNTs is similar to that of common highly charged polyelectrolytes

Physical origin of the intrinsic cathodic luminescence of an oxide-covered aluminium electrode

Photoluminescence spectra of thin-film aluminium oxide samples on aluminium show spectral lines at ca. 330 and 420 nm that are attributed to the F+ and F centers of aluminium oxide, respectively. Experimental results reveal that the F centers are responsible for the intrinsic cathodic luminescence of an oxide-covered aluminium electrode, too. The mechanism of the luminescence is based on charge transfer reactions at the oxide/electrolyte interface