Department of Chemistry, Institute of Science, Banaras Hindu University Varanasi 221005, India

0.9
cos
d =
IC Maurya, et al.
Fig. 4. FTIR spectra (a) and XRD pattern (b) of TNP and G-TNP.
Fig. 3. UV-Vis absorption spectra (a) and Tauc's plots for band-gap determination (b) of TNP and G-TNP.
( H )
(h =
eg)
twelfth
955
Solar Energy 194 (2019) 952–958
confirm the formation of highly crystalline G-TNP in pure anatase
through UV-Vis absorption spectroscopy.
Fig.
3a characteristics the com
parative light absorption of green synthesized TiO2 NPs
where, d is the average crystallite size, is the wavelength of X-ray, is
3.1. Optical properties
of FTIR spectra. The peaks appeared in the range of 400–700 cmÿ1 are
synthesized conventional employing method contains a broad peak at
spectrum, a broad absorption peak at ~285 nm for TNP and a strong
maximum (FWHM). Average crystallite size of TNP and G-TNP were
photon energy (hÿ) for different samples. The optical band-gap of G TNP and
TNP calculated from Tauc's plot corresponds to 2.9 eV and
band observed at 2900 to 3400 cmÿ1 is assigned to the stretching vi bration
of –OH and weakly bound water molecules
(León et al., 2017).
3.2. Structural and morphological characterization
where, ÿ is a constant, Eg is band-gap of the material, ÿ is the absorption
(Kushwaha et al., 2015).
The peak at 1630 cmÿ1 corresponds to a
method and green synthesis technique is shown in
Fig.
4a. The ap pearance
of sharp peaks for TiO2 nanoparticles using green synthesis
absorption peak at 306 nm were observed. Optical band-gap(s) of the
calculated to be 13 nm and 9 nm respectively.
3.2 eV respectively. This demonstrates that the band-gap energy of G TNP
has been significantly reduced compared to the conventional TNP.
electron microscope at an accelerating voltage of 200 kV. For details of
2ÿ values ~31° (marked as star, '*' in
Fig. 4b)
corresponding to (1 2 1)
70.3 and 75.1 corresponds to (1 0 1), (0 0 4), (2 0 0), (1 0 5), (2 1 1),
Morphology and microstructure of the synthesized nanoparticles
groups present in the synthesized materials.
Fig.
4b shows the FTIR
Fig.
5, TNP particles have highly agglomerated nearly spherical struct tures
having smoother surfaces with average particle size of
be referred.
The average crystallite size of the synthesized TiO2 NPs was esti mated
by the Debye Scherrer's equation:
(2)
(first)
attributed to the O–Ti–O lattice vibration of anatase phase of TiO2
(2 0 4), (1 1 6), (2 1 5) and (3 0 3) crystal planes respectively, which
Optical properties of the synthesized nanoparticles were analyzed
X-ray diffraction (XRD) pattern of TiO2 NPs using conventional
bending vibration of H–O bond
(Perumal and Gnana, 2014).
The broad
phase (JCPDS card no. 21-1272). However, XRD patterns of TNPs as
(G-TNP) and conventional TiO2 nanoparticles (TNP). Print the UV-Vis
the Bragg's diffraction angle, and is the angular full width at half
coefficient (cmÿ1), h is the Planck's constant and ÿ is the photon fre quency.
Fig.
3b shows the Tauc plots, ie variation of (ÿhÿ)
FTIR spectroscopic technique was used to confirm the functional
were used using HR-SEM and HRTEM analysis. As shown in
other instrumentation our earlier publication
(Maurya et al., 2018)
may
face of brookite phase
(Muniandy et al., 2017).
nanoparticles were determined by using the following equation,
1/2
versus

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