1. Single-walled carbon nanotubes: analyzed as a function of oxygenation/oxidation (e.g. comparison of wet-air oxidized, ozonized, and pristine tubes). Degree of order and alignment probed in powder, film, and aligned samples with results compared to those of graphite.
Refs.: Chem. Commun., v.7 , 772 (2004); Phys. Chem. Chem. Phys., v.7, 1103 (2005) [invited]; and J. Phys. Chem. B, v.109, 8489 (2005) [invited].
2. Multi-walled carbon nanotubes: studied as a function of degree of purification and oxygenation.
Ref.: ChemPhysChem, v.5, 1416 (2004).
3. As a model system for understanding charge transfer in novel architectural designs for solar cells, double-walled carbon nanotube (DWNT) – CdSe quantum dot (QD) (QDs with average diameters of 2.3 nm, 3.0 nm, and 4.1 nm, respectively) heterostructures have been fabricated. The individual nanoscale building blocks were successfully attached and combined using a hole-trapping thiol linker molecule, i.e. 4-mercaptophenol (MTH), through a facile, non-covalent π-π stacking attachment strategy. Transmission electron microscopy (TEM) confirmed the attachment of QDs onto the external surfaces of the DWNTs. We herein demonstrate a meaningful and unique combination of near-edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopies bolstered by complementary electrical transport measurements in order to elucidate the synergistic interactions between CdSe QDs and DWNTs, which are facilitated by the bridging MTH molecule that can scavenge photo-induced holes and potentially mediate electron redistribution between the conduction bands in CdSe QDs and the C 2 p-derived states of the DWNTs. Specifically, we correlated evidence of charge transfer as manifested by (i) changes in the NEXAFS intensities of π * resonance in the C K-edge and Cd M 3-edge spectra, (ii) a perceptible outer tube G-band down-shift in frequency in Raman spectra, as well as (iii) alterations in the threshold characteristics present in transport data as a function of CdSe QD deposition onto the DWNT surface. In particular, the separate effects of (i) varying QD sizes and (ii) QD coverage densities on the electron transfer were independently studied.
Ref.: J. Phys. Chem. C, v.119(47), 26327-26338 (2015).