Here the powder diffraction patterns of TiO2(B) nanowires and nanotubes are
compared with that of bulk TiO2(B). In both bulk and nanowire samples no
significant evidence of the presence of other TiO2 phases was observed. In the
nanotube pattern, however, traces of the anatase phase were found.
As expected, the peaks of the nanowires are much broader than those in the bulk sample. The peak broadening is due to the reduced dimensions of the nano-structured material, going from 0.1-0.5 μm to 20-50 nm, which results in an X-ray coherence length smaller than 600 Å. The peak broadening effect is much more pronounced for
10 20 30 40 50 60 70 N or m al iz ed in te ns ity (a .u .) 2(degrees)
TiO2(B) calculated pattern TiO2(B) bulk
TiO2(B) nanowires TiO2(B) nanotubes
the nanotube sample, since the tubes have a wall thickness ranging between 25 and 30 Å.
The structure of the TiO2(B) samples was further investigated using Raman
spectroscopy. The Raman spectra are presented in figure 3.3.
Figure 3.3 Raman spectra of bulk TiO2(B) (in black); TiO2(B) nanowires (in green)
and TiO2(B) nanotubes (in red).
The TiO2(B) spectral features are present for all morphologies; however, as expected, 100 200 300 400 500 600 700 800 900 1000 In te ns ity (a .u .) Wavenumber (cm-1) TiO2(B) bulk TiO2(B) nanowires TiO2(B) nanotubes
3.3.2 Morphology
The morphology of
microscopy (TEM) and scanning electron microscopy images of bulk TiO
The image
illustrates the TEM images for the TiO an estimation
diameter in the range of 20 nm to 50 nm and
Morphology
The morphology of the produced TiO
microscopy (TEM) and scanning electron microscopy images of bulk TiO2(B) are reported.
The images clearly show a wire trates the TEM images for the TiO an estimation of the
diameter in the range of 20 nm to 50 nm and
Chapter 3.
the produced TiO
microscopy (TEM) and scanning electron microscopy (B) are reported.
Figure 3.
clearly show a wire trates the TEM images for the TiO
the nanowires dimensions diameter in the range of 20 nm to 50 nm and
Chapter 3. Synthesis and Characterisation of TiO
the produced TiO2(B) was examined using transmission electron
microscopy (TEM) and scanning electron microscopy (B) are reported.
Figure 3.4 TEM images of bulk TiO
clearly show a wire-like morphology for the bulk material. trates the TEM images for the TiO2(B) nanowires.
nanowires dimensions diameter in the range of 20 nm to 50 nm and
Synthesis and Characterisation of TiO
(B) was examined using transmission electron microscopy (TEM) and scanning electron microscopy
TEM images of bulk TiO
like morphology for the bulk material. (B) nanowires.
nanowires dimensions can be made
diameter in the range of 20 nm to 50 nm and a length which can reach up to 10
Synthesis and Characterisation of TiO
(B) was examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In
TEM images of bulk TiO2(B).
like morphology for the bulk material.
From the TEM image analysis can be made. The nano
length which can reach up to 10
Synthesis and Characterisation of TiO2(B) materials
(B) was examined using transmission electron In figure 3.
like morphology for the bulk material. Figure TEM image analysis
nanowires exhibit length which can reach up to 10
(B) materials
(B) was examined using transmission electron igure 3.4 TEM
Figure 3.5 TEM image analysis exhibit a length which can reach up to 10μm.
Scanning electron microscop homogeneity
particulates.
The TEM images reported in f
of the sample. An estimate of the size was obtained by TEM image nanotubes show an outer diameter of
The material
canning electron microscop homogeneity and the
particulates. An image taken at the SEM is
The TEM images reported in f
of the sample. An estimate of the size was obtained by TEM image nanotubes show an outer diameter of
material displayed
Chapter 3.
canning electron microscopy the high quality
An image taken at the SEM is
Figure 3.7 TEM images of TiO
The TEM images reported in figure 3.
of the sample. An estimate of the size was obtained by TEM image nanotubes show an outer diameter of
displayed high homogeneity
Chapter 3. Synthesis and Characterisation of TiO
(SEM) studies
high quality of the sample, consisting mainly of An image taken at the SEM is
TEM images of TiO
igure 3.7 clearly highlight the nanotubular morphology of the sample. An estimate of the size was obtained by TEM image
nanotubes show an outer diameter of 8-12 high homogeneity.
Synthesis and Characterisation of TiO
studies confirmed the high morphological of the sample, consisting mainly of
An image taken at the SEM is reported in
TEM images of TiO2(B) nanotubes
clearly highlight the nanotubular morphology of the sample. An estimate of the size was obtained by TEM image
12 nm and an
Synthesis and Characterisation of TiO
confirmed the high morphological of the sample, consisting mainly of
reported in figure 3.6.
nanotubes.
clearly highlight the nanotubular morphology of the sample. An estimate of the size was obtained by TEM image
an internal diameter
Synthesis and Characterisation of TiO2(B) materials
confirmed the high morphological of the sample, consisting mainly of fibrous
clearly highlight the nanotubular morphology of the sample. An estimate of the size was obtained by TEM image analysis;
internal diameter of
(B) materials
confirmed the high morphological fibrous nano-
clearly highlight the nanotubular morphology analysis; the of 5-8 nm.
3.3.3 Surface area analysis
Surface area measurements were carried out on the TiO2(B) samples and the
nanotube titanate precursor using the Brunauer-Emmett-Teller (BET) method. The obtained surface area values are reported in table 3.2.
Table 3.2 Surface area values for the TiO2(B) samples and the titanate nanotube precursor.
As expected, the nanowires exhibit a larger surface area (~28 m2g-1) compared with the bulk material (~18 m2g-1). The nanotube precursor has a very large surface area
which is almost one order of magnitude larger than the nanowire sample. However, after the annealing and the formation of the TiO2(B) structure, the surface area of the
nanotubes decreases. This is believed to be due to damage sustained by some of the nanotubes which occurs during the calcination stage, leading to the partial collapse of