Nana Amponsah Kyeremateng

Highly conformal electrodeposition of copolymer electrolytes into titania nanotubes for 3D Li-ion batteries

The highly conformal electrodeposition of a copolymer electrolyte (PMMA-PEO) into self-organized titania nanotubes (TiO2nt) is reported. The morphological analysis carried out by scanning electron microscopy and transmission electron microscopy evidenced the formation of a 3D nanostructure consisting of a copolymer-embedded TiO2nt. The thickness of the copolymer layer can be accurately controlled by monitoring the electropolymerization parameters. X-ray photoelectron spectroscopy measurements confirmed that bis(trifluoromethanesulfone)imide salt was successfully incorporated into the copolymer electrolyte during the deposition process. These results are crucial to fabricate a 3D Li-ion power source at the micrometer scale using TiO2nt as the negative electrode.

Electrochemical Fabrication and Properties of Highly Ordered Fe-Doped TiO2 Nanotubes

Highly-ordered Fe-doped TiO(2) nanotubes (TiO(2)nts) were fabricated by anodization of co-sputtered Ti-Fe thin films in a glycerol electrolyte containing NH(4)F. The as-sputtered Ti-Fe thin films correspond to a solid solution of Ti and Fe according to X-ray diffraction. The Fe-doped TiO(2)nts were studied in terms of composition, morphology and structure. The characterization included scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Mott-Schottky analysis. As a result of the Fe doping, an indirect bandgap of 3.0 eV was estimated using Taucs plot, and this substantial red-shift extends its photoresponse to visible light. From the Mott-Schottky analysis, the flat-band potential (E(fb)) and the charge carrier concentration (N(D)) were determined to be -0.95 V vs Ag/AgCl and 5.0×10(19) cm(-3) respectively for the Fe-doped TiO(2)nts, whilst for the undoped TiO(2)nts, E(fb) of -0.85 V vs Ag/AgCl and N(D) of 6.5×10(19) cm(-3) were obtained.