169 research outputs found
Stability and Electronic Properties of TiO2 Nanostructures With and Without B and N Doping
We address one of the main challenges to TiO2-photocatalysis, namely band gap
narrowing, by combining nanostructural changes with doping. With this aim we
compare TiO2's electronic properties for small 0D clusters, 1D nanorods and
nanotubes, 2D layers, and 3D surface and bulk phases using different
approximations within density functional theory and GW calculations. In
particular, we propose very small (R < 0.5 nm) but surprisingly stable
nanotubes with promising properties. The nanotubes are initially formed from
TiO2 layers with the PtO2 structure, with the smallest (2,2) nanotube relaxing
to a rutile nanorod structure. We find that quantum confinement effects - as
expected - generally lead to a widening of the energy gap. However,
substitutional doping with boron or nitrogen is found to give rise to
(meta-)stable structures and the introduction of dopant and mid-gap states
which effectively reduce the band gap. Boron is seen to always give rise to
n-type doping while depending on the local bonding geometry, nitrogen may give
rise to n-type or p-type doping. For under coordinated TiO2 surface structures
found in clusters, nanorods, nanotubes, layers and surfaces nitrogen gives rise
to acceptor states while for larger clusters and bulk structures donor states
are introduced
Electrochromism of DC magnetron sputtered TiO2 thin films: Role of deposition parameters
Synthesis of TiO2 Thin Films: Relationship Between Preparation Conditions and Nanostructure
One-step realization of open-ended TiO2 nanotube arrays by transition of the anodizing voltage
Ion implantation and annealing for an efficient N-doping of TiO2 nanotubes
Self-organized anodic titaniananotube layers were doped with nitrogen successfully using ion implantation. Photoelectrochemical measurements combined with XRD measurements show that the damage created by ion bombardment ( that leads to a drastic decrease of the photoconversion efficiency) can be "annealed out" by an adequate heat treatment. This results in a N-doped crystalline anatase nanotube structure with strongly enhanced photocurrent response in both the UV and the visible range
Photoelectrochemical properties of N-doped self-organized titania nanotube layers with different thicknesses
TEMPLATE SYNTHESIS OF NICKEL, COBALT, AND NICKEL HEXACYANOFERRATE NANODOT, NANOROD, AND NANOTUBE ARRAYS
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