We synthesized nanotubes and nanowires of π-conjugated poly (3-methylthiophene) (P3MT) by using nanoporous anodic aluminum oxide (Al2O3) template through electrochemical polymerization method. From scanning electron microscope and transmission electron microscope photographs, we observed the formation of nanotubes with diameters of 100–200 nm and wall thicknesses of 5–10 nm. Relatively long nanotubes and nanowires of P3MT (about 40μm in length) were obtained. To discern the structural and optical properties of the systems, we measured ultraviolet and visible absorbance and Fourier transform-infrared spectroscopy. We observed that the doping level, the π-π* transition peak, and bipolaron peaks in P3MT nanotubes varied with synthetic temperature. The photoluminescence (PL) spectra of the P3MT nanotubes solution were observed at ∼490nm. For the P3MT nanotubes synthesized at lower temperatures, the PL peaks became sharper and the resistance decreased.

Adsorption behaviors of dodecanethiol (C12H25SH) molecules are investigated on the surface of single-walled carbon nanotubes (SWCNTs) with vibrational and X-ray photoelectron spectrometers. The active adsorption sites are proved as Stone-Wales (SW) defects (5–7 ring defects). The SW defect-removed SWCNTs formed by reacting nanotubes with allyl acrylate molecules are compared with pristine SWCNTs in dispersion and field emission. The former shows higher dispersion and field emission than the latter.

Single-walled carbon nanotubes (SWNTs) and C 60 -encapsulated SWNTs (C 60 @SWNTs) are introduced to Rusensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an RuL 2 (NCS) 2 /DAPV/SWNTs/ITO cell and an RuL 2 (NCS) 2 /DAPV/C 60 @SWNTs/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of C 60 @SWNTs. To explain the photocurrent increase, the reverse-field emission method is used, i.e., RuL 2 (NCS) 2 /DAPV/SWNTs/ITO cell (or RuL 2 (NCS) 2 /DAPV/ C 60 @SWNTs/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., β (field enhancement factor) and emission currents in the reverse-field emission with C 60 @SWNTs indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.

Photo-luminescent dye, 1-(2-amino-phenyl) naphthalene-2-ylamine (APNA) molecules were synthesized and encapsulated inside single-walled carbon nanotubes (APNA@SWNTs) in vacuum. Here we measured X-ray diffraction (XRD) pattern and attenuated total reflectance (ATR) spectrum to confirm the encapsulation of APNA molecules inside SWNTs. Strong photoluminescence (PL) spectrum was observed around 400 nm at an excitation of 326 nm. We employed the PL intensity of the dye to reveal suspension stability of SWNTs in solvents. The intensity of PL spectrum increased as a function of SWNTs suspension stability, i.e., the PL intensity was proportional to suspension stability of SWNTs in various solvents.

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