Differentiating between ortho- and para-Quinone Surface Groups on Graphite, Glassy Carbon, and Carbon Nanotubes Using Organic and Inorganic Voltammetric and X-ray Photoelectron Spectroscopy Labels

ortho-Quinones can be differentiated from other oxygen-containing surface functional groups on the surfaces of graphite, glassy carbon, "bamboo-like", and "hollow-tube" multiwalled carbon nanotubes and single-walled carbon nanotubes by chemically labeling them with either an inorganic hexamminechromium(III) complex or organic 1,2-phenylenediamine derivatives. Both types of labels can be observed using cyclic voltammetry or by X-ray photoelectron spectroscopy and used to quantify the numbers and relative distribution of orifto-quinones from other oxygen-containing species on the surface including electroactive para-quinones which are not labeled. Labeling of ortho-quinones with 1,2-phenylenediamine derivatives results in the formation of phenazine-like adducts on the graphitic surface which have a distinct voltammetry particularly from that of the underivatized para-quinones. © 2007 American Chemical Society.