Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of
functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid
(HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The
morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped
TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface
-COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical
properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in
band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized
materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the
graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.
An easy process was developed to fabricate TiO2 nanowires sensitized with CdS and CdTeS quantum dots (QDs). CdS
and CdTeS nanoparticles were grown in situ by a colloidal method. No pretreatment of the TiO2 nanowires was required
prior to nanoparticle generation. Functionalization of CdS and CdTeS QDs was not needed to anchor these nanoparticles
to TiO2 surface. The resulting nanostructure assembly and composition was confirmed by transmission electron
microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electronic structure of TiO2 nanowires was
preserved as indicated by Raman spectroscopy. The sensitization of the TiO2 nanowires by the QDs was confirmed by
photocurrent measurements. This study allows the generation of strongly anchored CdS and CdTeS QDs on TiO2
nanowires surface without the introduction of a linker molecule which presence decreases the electron injection
efficiency.
Highly ordered TiO2 nanowire arrays were prepared on the surface of Functionalized Graphene sheets (FGSs) by solgel
method using titanium isopropoxide monomer with acetic acid as the polycondensation agent in the green solvent,
supercritical carbon dioxide (sc-CO2). Morphology of synthesized materials was studied by SEM and TEM. Optical
properties of the nanocomposites studied by UV spectroscopy which showed high absorption in visible area as well as
reduction in their band gap compared to TiO2. By high resolution XPS, chelating bidentate structure of TiO2 with
carboxylic group on the surface of graphene sheets can be confirmed. Improvement in the optical properties of the
synthesized composites compared to TiO2 alone was confirmed by photocurrent measurements.
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