Characterization of Ag doped WO3 synthesized by
electrospinning
Jananan Kamsri1,2, Titipun Thongtem3, Somchai Thongtem1,4
1
Department of Physics and Materials Science, Faculty of Science, Chiang Mai
University, Chiang Mai 50200, Thailand
2
The Graduate School, Chiang Mai University, Chiang Mai 50200, Thailand
Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai
50200, Thailand
4
Materials Science Research Center, Faculty of Science, Chiang Mai University,
Chiang Mai 50200, Thailand
3
Abstract. SEM technique was assisted to selected the best condition of 5 wt% Ag doped WO3
nanofiber which synthesized by electrospinning method and calcined at 550 ๐C for 2 hours then
were investigated the characteristic via X-ray diffraction, Raman spectroscopy,
photoluminescence, UV-visible, FTIR and TEM technique. The results show that is product of
orthorhombic Ag-WO3 nanofiber with 60 nm diameter and 2.53 eV photon energy gap
semiconductor.
Keywords : Ag-WO3; Electrospinning; XRD; FTIR; SEM
Introduction
Nanotechnology is the technology involved in the production and application of the small substances
about one billionth of a meter (10-9 m) which began a major role to humans in present and even more in
the future research. Especially for solving the crisis demand for health, energy and environment while
countries all over the world focus on the development of science and technology increasingly, whereupon
enormously impact on the economy and international competitiveness. [1, 2]
This experiment attempted to synthesize the new composite material nanofiber that is Ag-doped WO3
with mixing precursors and varied electrospinning parameters from former pure WO3 [3], then investigate
characteristics of the products
Experimental procedure
Fabricated process began with 1) ammonium mega tungstate hydrated (H26N6O40W12 • H2O, AMH
99.0%) dissolved in deionized water 3 ml determined as 0.3 mmol concentration, 2) polyvinyl alcohol
(PVA) molecular weight 125,000 g/mol dissolved in deionized water 20 ml varied amount to 0.9, 1.0,
1.1, 1.2, 1.3 g and 3) 5 wt% of Silver nitrate (AgNO3), were mixed together at a temperature of 80 °C
for 30 minutes. After that, all mixtures were fill into syringe which attach the metal needle then were
brought to synthesize by electrospinning method along to 5, 10, 15, 17 kV voltage applied, mean to
attached on the aluminum foil receiver which aligned the distance from the syringe nose up to 15
centimeters (fig 1. (a)) until the white cloud of fibers were being noticed (fig 1.(b)) and the mixtures
was out of stock, variant products was named as B1 – B15 for before-calcined products. Then products
had been detached from receivers to calcined at 550 °C for 2 hours to be named A1 – A15 for aftercalcined products (Table. 1). The best product were chosen by compare on the results of SEM images
(Fig. 2) which 1.2 g PVA mixed and 15 kV energy applied (A9, B9) (fig. 2 (g, h, i, j)) were chosen.
Products from the chosen conditions has been characterized by different methods.
Table 1. The variant parameters of electrospun fibers.
PVA (g)
Voltage
(kV)
0.9
1.0
1.1
1.2
1.3
5
N/A
N/A
N/A
N/A
N/A
10
A1,B1
A2,B2
A3,B3
A4,B4
A5,B5
15
A6,B6
A7,B7
A8,B8
A9,B9
A10,B10
17
A11,B11
A12,B12
A13,B13
A14,B14
A15,B15
Fig. 1 (a) syringe of mixture set up against aluminum foil, (b) white cloud of fibers attached on
aluminum foil
Results and Discussion
consideration of 5wt% Ag doped WO3 (Ag-WO3) fiber’s morphology which occurred. The role of 0.5
kV voltage applied with all PVA added conditons, any fiber seems did not manufactured because of not
enough voltage to pushed out precursor across setup distances, when others 10, 15, 17 voltage were
applied, it had performed white cloud of nanofibers on aluminum foil receivers which could be noticed
by human’s eyes.
SEM results (fig. 2) shows some variant of nanofibers morphology trend which depend on PVAs and
voltage applied participatory, the increment of attached nanofibers on the receiver was depended on
addition of PVA ascending, similar to voltage applied that increase amount of attached nanofiber
belonged to provided power in ascending. However eligible condition is A9 or B9 (fig. 2 (g, h, i, j))
because of undercondition products of B and A (1 - 5, 6 - 8, 11 - 13) had not been produced enough
amount of fibers for detaching and they composed of superthin fibers with a lot of beads before calcined,
And after calcined the fibers were cut off fragmentary. Fig. 2 (a, b, c, d, e, f, k, l)) represent example of
undercondition SEM images of B1, A1, B5, A5, B8, A8, B11, A11 repectively. For overcondition
products, B and A (10, 14, 15) which represent in fig. 2 (m, n, o, p) for example of B15 and A15 was
synthesized over 100 nm diameter fibers and web cross-linked morphology formed affected by high
stickiness precursor which may requires high voltage energy to perform a task. XRD spectra (Fig. 3 (a))
shows spectrum of WO3 correspond to JCPDS No.71-0131 with Orthorhombic crystal system and Pmnb
space group, compare between Ag-WO3, notice that very similar in major peaks, so anyway there are
Fig. 2 SEM images of electospun fibers (a)B1, (b)A1, (c) B5, (d)A5, (e)B8, (f)A8, (g,i)B9,
(h,j)A9, (k)B11, (l)A11, (m,o)B15, (n,p)A15
some difference in minor peaks, thus it couldn’t be assure what type of Ag compound occurred. The
successful of doping Ag-WO3 compound should be showed out in this experiment. FTIR curve (fig. 3
(b)) show indifferent curves between WO3 and Ag-WO3 compare to precursor. All three curves compose
of very broad peak at 3410 cm-1 represent for O – H stretching of Alcohol, minor broad peak at 2941 cm1
for C – H stretching of alkane, minor double peaks at 1715 cm-1 and 1645 cm-1 for C = O stretching
of ketone group and C = C stretching of alkene group respectively[4]. The different is when the precursor
was calcined at 550 Co results to both WO3 composed peaking curve at 2360 cm-1 represent for O = C =
O stretching mode of CO2 which a result of combustion effect[5], by this way two peaks at 819 cm-1 and
768 cm-1 were show W – O – W stretching mode of WO3 [6]. The Raman curve (Fig. 3 (c)) is about 5
wt% Ag doped curve, showing multiple peaks included at 803cm-1, 717 cm-1 correspond to W-O-W
stretching vibration mode, the peak at 272 cm-1 is corresponding to O-W-O bending vibration mode [7],
Fig. 3 Ag-WO3 nanofiber compare to WO3 nanofiber with the same electrospun conditions
(a) XRD spectra, (b) FTIR spectra, (c) Raman spectra, (d) photoluminescence curve,
(e) UV-visible absorption curve and (f, g, h) TEM image for Ag-WO3
furthermore the peaks at 906 cm-1 and 938 cm-1 show result of WO3 curve induced by Ag addition [8].
Wise to Photoluminescence curve (fig. 3 (d)) which shows general excitation spectrum of WO 3 at 314
nm [9] with slightly reduce trend of curve compared between WO3 and Ag- WO3 at 445.5 nm, so it could
be analyzed that was success to fabricate Ag-WO3 compound [10]. UV-visible absorption spectra has
been used to determined optical energy gap (Eg) of WO3 compare to Ag-WO3(fig. 3 (e)), where the plot
of photon energy(hʋ) versus absorption coefficient of photon energy square(αhʋ)2 show the determined
Eg of WO3 nanofiber equal 3.09 eV and the Eg of Ag-WO3 equal 2.53 eV. TEM images (fig. 3 (g), (h))
show nanostructure of fabricated Ag-WO3 nanofibers, composing of coagulated 60 x 60 x 60 nm
nanopolygons formed linearity to be nanofibers which and lattice index has been shown in fig. 3 (f)
Conclusions
The composite material of Ag-WO3 nanofiber was successfully synthesized by electrospinning method
with condition of 5 wt% Ag doped, 15 kV voltage applied, 1.2 PVA added and 15 cm electrospinning
distance. The after calcined morphology is dark yellow substances with about 60 nm diameter fibers
consisted of orthorhombic crystal structure corresponding to JCPDS database no.71-0131 belonged in
Pmnb space group. FTIR curve shows peaks 819 cm-1 and 768 cm-1 for W – O – W stretching mode of
WO3 and the 2360 cm-1 which dissimilar from the precursor. The unique characteristic is confirmed by
Raman curve at peaks 906 cm-1 and 938 cm-1 which show effect of WO3 curve induced by Ag addition,
likely to PL curve which has a slightly reduce trend of curve compare between WO3 and Ag-WO3 at
445.5 nm wavelength, And there is determined photon energy gap from UV-vis. spectrum as 2.53 eV.
Acknowledgment: This work was supported by the Graduated School of Chiang Mai University.
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