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 ortho-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.

Quinone groups on the surface of edge-plane and basal-plane pyrolytic graphite electrodes, and, for the 1st time, bamboo-like multi-walled carbon nanotubes (b-MWCNTs), are labeled with a voltammetric tag, 2,4-dinitrophenylhydrazine (2,4-DNPH). The voltammetric response of these materials was studied in both aq. and nonaq. electrolyte solns., and mechanisms are proposed for each media involving the voltammetrically controlled cleavage of the 2,4-DNPH adduct. Thus, these materials can be used for potentiometrically controlled chem. release, and as such may find application in, for example, drug delivery systems. In aq. media, this cleavage results in the conversion of the surface quinonyl groups into surface arylnitroso species. This conversion is confirmed by studying the voltammetric response of the arylnitroso/arylhydroxylamine redox couple, formed after cleavage of the 2,4-DNPH adduct in the presence of L-glutathione, which was shown in the authors' previous work to react with arylnitroso species on the surface of graphitic carbon materials. [on SciFinder(R)

A generic approach for the detection of electroactive species in potential ranges that would normally be inhibited due to the stripping of the electrocatalytic material is presented. We demonstrate, via the example of the electrochemical oxidation of hydrazine, that palladium nanoparticle (< 1 nm) decorated bamboo multi-walled carbon nanotubes exhibit a metastability such that they allow the sensing of hydrazine in the pH range where palladium metal would normally be voltammetrically stripped (oxidized) from the surface of convectional electrodes.

A method of constructing a "designer interface" consisting of either monolayers or multilayers of chem. modified microbeads is reported, whereby the shape of the interface as well as the interfacial chem. imparts "diffusional protection" to the underlying surface material. [on SciFinder(R)