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Applied Surface Science 257 (2011) 8850–8856
Contents lists available at ScienceDirect
Applied Surface Science
journal homepage: www.elsevier .com/ locate /apsusc
The potential use of nanosilver-decorated titanium dioxide nanofibers for toxin
decomposition with antimicrobial and self-cleaning properties
Chutima Srisitthiratkul, Voraluck Pongsorrarith, Narupol Intasanta∗
National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), 130 Thailand Science Park, Phahonyothin Road, Klong Luang,
Pathumthani 12120, Thailand
a r t i c l e i n f o
Article history:
Received 29 December 2010Receivedin revised form 18 April 2011
Accepted 18 April 2011
Available online 12 June 2011
Keywords:
Titanium dioxide
Nanofibers
Electrospinning
Silver
Nanoparticles
Japan Industrial Standard (JIS)
Nitrogen oxide
Volatile organic compound (VOC)
Staphylococcus aureus
Escherichia coli
Wetting
SuperhydrophilicitySelf cleaning
a b s t r a c t
While chemical and biological attacks pose risk to human health, clean air isof scientific, environmental
and physiological concerns. In the present contribution, the potential use of nanosilver-decorated tita-
nium dioxide (TiO2) nanofibers for toxin decomposition with antimicrobial activity and self-cleaning
properties was investigated. Titanium dioxide nanofibers were prepared through sol–gel reaction
followed byan electrospinning process. Following the Japan Industrial Standard (JIS) protocol, decompo-
sitions of nitrogen oxide (NOx) and volatile organic compound (VOC) by the TiO2 nanofibers suggested
that these materials were capable of air treatment. To further enhance their anti-microbial activity, silver
nanoparticles were decorated onto the TiO2 nanofibers’ surfaces via photoreduction of silver ion in the
presence of the nanofibers suspension. Furthermore, tests of photocatalytic activity of the samples were
performed by photodegradingmethyleneblue in water. The nanofibrousmembranesprepared from these
nanofibers showed superhydrophilicity under UV. Finally, the possibility of using these hybrid nanofibers
in environmental and hygienic nanofiltration was proposed, where the self-cleaning characteristics was
expected to be valuable in maintenance processes.
© 2011 Elsevier B.V. All rights reserved.
1. Introduction
Clean air is of scientific, environmental and health concerns
[1,2]. Both chemical [3,4] and biological[5] contaminants pose risks
to both industrial settings and household. Nitrogen oxide (NOx)
[4] and volatile organic compounds (VOCs) [3] are among com-
mon noxious byproducts from transportation and manufacturing.
In addition, bacteria and virus have been the pinpoint of physio-
logical apprehension in recent times [5]. In general, antimicrobial
proteins in the pulmonary systems constitute to our physiolog-
ical defense mechanism [6]. However, recent reports on effectsof airborne chemical and biological pollutions on human health
[4,5] implied that more effective protection systems are still highly
sought after.
Degradation of chemical pollutions [7–9] and biological dis-
infection [10,11] has been proven possible with photocatalysis.
Photocatalysts harvest light as an energy source to excite elec-
∗ Correspondingauthor. Tel.: +66 2564 7100x6580; fax: +66 25646981.
E-mail address: narupol@nanotec.or.th(N. Intasanta).
URL: http://www.nanotec.or.th (N. Intasanta).
trons from valence to conduction bands [12,13]. The generated
electrons and holes make possible reductive and oxidative reac-
tions of organic pollutant into carbon dioxide and water. Titanium
dioxide (TiO2), a metal-oxide semiconductor, has been studied and
widelyused as a photocatalytic material owing to itsrelatively high
photocatalytic activity, chemical stability, non-hazardous nature,
superhydrophilic property and antibacterial activity [13,14]. The
TiO2 photocatalyst which is driven by the clean energy of sunlight
is expected to be applied in many potential applications such as
self-cleaning [15–18], degradation of organic pollutants [19–22],
photoelectrode and electrochromic device [23–26].Due to their high surface area and unique properties, the use of
nanomaterials has gained tremendous attention in both industrial
and academic arena. In photocatalysis, exploitation of nanoma-
terials involves some limitation which depends strongly on their
dimension. Spherical-shaped nanomaterials inherit practical prob-
lemsrelatingto self-agglomeration [27,28]which lead to lowactive
surface area and, thus, low efficiency. In contrast, one-dimensional
materials such as nanofibers show much less agglomeration.
As such, electrospinning is a facile and cost-effective route to
generate fibers with diameters at nanometer length scale [29–32].
As a typical approach, metal alkoxides are used as precursors for
0169-4332/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.apsusc.2011.04.083
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C. Srisitthiratkul et al./ Applied Surface Science 257 (2011) 8850–8856 8851
the syntheses of several semiconductor nanofiber such as tita-
nium dioxide [13,14]. Variation of solution properties and spinning
parameters leads to a wide range of one-dimensional nanostruc-
tures ranging from single to multi-componentnanofibers [33]. As a
consequence, this technique has been exploited for medical, mate-
rial and energy applications [13,14].
In the present contribution, TiO2 nanofibers were prepared
through sol–gel reaction and electrospinning process [29–32]. The
potentialuse of these nanofibersas airnanofilters wasshownin the
decompositions of nitrogen oxide (NOx) and volatile organic com-
pound (VOC) under Japan Industrial Standard (JIS) protocol[34]. To
further enhance their anti-microbial activity, silver nanoparticles
were decorated onto the nanofibers’ surfaces by photoreduction
[35–38]. In so doing, aqueous-base photoreduction of silver ion
in the presence of nanofiber suspension resulted in nanosilver-
decorated TiO2 nanofibers. Furthermore, tests of photocatalytic
activity of the samples were performed by photodegrading methy-
lene blue in water. The nanofibrous membranes prepared from
these nanofibers showed superhydrophilicity under UV. Finally,
the possibility of using these hybrid nanofibers in environmental
and hygienic nanofiltration was proposed, where the self-cleaning
characteristics was expected to be valuable in maintenance pro-
cesses.
2. Experimental
2.1. Chemicals
Titanium (IV) isopropoxide (TiP, 97%, Aldrich), P25 (Degussa,
Germany), hydrochloric acid (HCl, 37%, Carlo Erba), ethanol
(C2H5OH, 99.8%, Carlo Erba), polyvinylpyrrolidone (PVP,
M w ∼ 360,000, Fluka), pluronic (M w ∼ 5800, Aldrich) and silver
nitrate (AgNO3, Aldrich) were used as received.
2.2. Preparation of titanium dioxide nanofibers
Titanium nanofibers were prepared by an electrospinning pro-
cess [29–32,39]. The precursor gel for electrospinning titaniumdioxides nanofibers was prepared using titanium (IV) isopropox-
ide, hydrochloric acid, ethanol, polyvinylpyrrolidone and pluronic.
In the synthetic procedure, 0.5g of pluronic and 0.5g of PVP were
firstly dissolved in 7 g of ethanol under magnetic stirring. In a sep-
arate beaker, a TiO2 sol was prepared by adding 3.56g of TiP into
a mixture of 2g of ethanol and 0.25ml of HCl. Then, this solution
was mixed with the PVP–pluronic solution followed by magnetic
stirring at room temperature for 15min. The resulting precursor
gel was heated at 50◦C for 24 h.
In the electrospinning set up, the precursor gel was loaded into
a 3 ml polypropylene syringe barrel, equipped with a 21-guage,
stainless steel, flat tip needle connected to a high-voltage supply
(Spellman, USA). During the process, the solution was fed at a con-
stant rate of 0.3ml/h by a syringe pump (Vernon Hills, USA). Anelectrical potential of 10kV was then applied between the tip of
the needle and the grounded aluminum foil target which were
15cm apart. The as-spun nanofibers were calcined at 500 ◦C f o r 4 h
under air in order to remove organic contents and form crystalline
titanium dioxide.
2.3. Preparation of nanosilver-decorated titanium dioxide
nanofibers
Deposition of nanosilver onto the surfaces of titanium dioxide
nanofibers was performed by a facile and cost-effective photo-
chemical reaction [35]. The following protocol is given as an
example. Firstly, 60mg of calcined titanium dioxide nanofibers
were dispersed in 60ml deionized water and sonicated for 10min.
Immediately afterward, 0.6 mg of silver nitrate was added and the
solution was magnetically stirred for 10min. Then UV irradiation
at 365nm was applied onto the solution under magnetic stirring
for another 1 h. The resulting dark dispersion was filtered, washed
and dried before further characterization. Different amounts – 2,
5 and 10wt.% – of silver were deposited onto titanium dioxide
nanofibersby varying silvernitratecontentfrom1.2,3.0and 6.0mg,
respectively.
2.4. Preparation of nanofibrous layers for gas-phase
photocatalytic and contact angle measurement
Nanofibrous layers were prepared for gas-phase photocatalytic
and contact angle measurements. In a typical protocol, 200 mg of
titanium dioxide nanofibers were dispersed in 2 ml of deionized
water and sonicated for 5 min. Then, the resulting dispersion was
spreadover a 5 cm×10cm glass slide before drying at 70◦Cfor1 h.
As a reference, P25 layer was prepared with the same method.
3. Characterization and instrumentation
3.1. X-ray diffraction
The crystal structures presented in the titanium dioxide
nanofibers were determined by powder X-ray diffraction or XRD
method. The measurements were carried out with JOEL, JDX-3530,
2 kW instrument at room temperature with CuK as the irradi-
ation source. The patterns were recorded over the angular range
of 15–80◦ (2 ), using scan rate of 0.02◦/min. The average size of
nanosilver decorating on the fibers was calculated from FWHM
using Program MDI Jade 6.5.
3.2. Electron microscopy
The nanofibers’ morphologies were characterized by scanning
electron microscope (SEM, S3400N, Japan) and transmission elec-
tron microscope (TEM, JEOL JEM-2010). The spatial distribution of silver element and nanosilver was determined from SEM under
elemental mapping mode.
3.3. Decomposition of model toxin
The decompositionsof nitrogen oxide(NOx) andvolatileorganic
compound (VOC) followed Japan Industrial Standard (JIS) protocol
[34,40,41]. In a typical protocol,100 mg of activematerials wasson-
icated in 2 ml deionizedwater. The resulting slurrywas coated on a
5 cm×10cm glass substrate. The concentration of active materials
was 2 mg/cm2. The experiment was conducted at AIST, Japan.
3.4. Photoluminescence
Photoluminescence was measured at room temperature with
Perkin Elmer LS-55 Fluorescence Spectrometer using a high energy
pulsed xenon source for excitation.
3.5. Photocatalytic activities
The photocatalytic activities of the samples were performed
against degradation of methylene blue, using 300W high-pressure
Hg lamp UV source. Methylene blue has been used widely as a
standard model contaminant for photocatalysis [42]. Before the
photoreaction, 10 mg of the prepared nanofibers was dispersed in
20ml of 5ppm methylene blue solution for 10min using ultra-
sonicator (Crest, Malaysia). The suspension was kept in the dark
and continuously magnetically stirred for 30min to equilibrate the
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adsorption–desorption processes [42]. Subsequently, the result-
ing suspension was illuminated with UV under magnetic stirring.
The distance between the UV source and the reaction containers
was fixed at 10 cm. After every given interval of UV irradiation,
a 1 ml aliquot of the sample was collected, centrifuged and fil-
tered to remove the photocatalyst. The concentration of methylene
blue was measured with UV-Vis spectrophotometer (Perkin Elmer,
Lambda 650, USA) at 663 nm, the maximum absorption of methy-
lene blue.
3.6. Antibacterial activities
Antibacterial activities of samples were examined by agar diffu-
sion method [43–45], where Staphylococcus aureus (S. aureus, ATCC
6538) and Escherichia coli (E. coli, ATCC 25922) were utilized as
Grampositive and Gramnegative bacterial strains, respectively. An
antimicrobial agent was utilized as a positive control. On each test-
ing plate,three small dishes containing similar samplewere placed
in close proximity. Another dish containing antibacterial agent was
placed towards the upperarea. Lackof inhibitory zonesimpliedthat
therewere no antibacterial activities. Formationof inhibitoryzones
entailed antibacterial activities. Zones of inhibition were averaged
from the three small dishes on the same testing plate.
3.7. Contact angle measurements
Contact angle measurements were performed using Tensiome-
ter with water as a probe liquid (Dataphysics Instruments, TC/TPC
150). A water droplet was placed onto the surface of a nanofibrous
membrane.Staticcontact angleswere thenmeasured.Six measure-
ments were made on different areas and the average values were
reported.
4. Results and discussion
Electrospinning was chosen to fabricate TiO2 nanofibers from
titanium alkoxide precursor containing PVP as a polymer additive.This facile approach gave rise to organic–inorganic nanofibers with
diameter at nanometer length scale. To complete the hydrolysis,
condensation and elimination of all the organic components, calci-
nation was applied. The physical characteristics of the TiO2 fibers
after calcination at 500◦C were unveiled by SEM. Fig. 1a shows an
SEM micrograph of the resulting TiO2 nanofibers. These nanofibers
appeared smooth with diameters of about 200–300nm which
were quantitatively evaluated using their high-magnification SEM
images. Afterthe preparation of nanofibrous layers, whichincluded
grinding the catalyst, the nanofibers became broken with their
average length decreased to about 5m. As shown in Fig. 1b, the
layer was not only fibrous but also highly porous. As evident, the
fiberswere fullydispersed in thelayer. This characteristic wasquite
the opposite from most of spherical-shaped nanomaterials whichtended to agglomerate. Self-agglomeration of photocatalytic nano-
materials might lead to a decrease in accessible active surface and,
thus, their efficiencies.
The potential use of these nanofibers as air nanofilters was
shown in the decompositions of nitrogen oxide (NOx) and volatile
organic compound (VOC) under Japan Industrial Standard (JIS) pro-
tocol. Japanese Industrial Standards (JIS), stipulated the standards
employed for procedures in Japanese industries. The standard-
ization progression has been synchronized by Japanese Industrial
Standards Committee. JIS has been adopted widely in academia and
industries [34,40,41]. From JIS R 1701-3:2008, Toluene, a common
noxious solvent extensively used in industries, wasused as a model
toxin for VOC decomposition measurement. Similarly, JIS R 1701-
1:2010 or ISO 22197-1:2007 exploited NOx to represent harmful
Fig. 1. Physical characteristics of photocatalyst nanofibers. (a) SEM micrograph of
electrospun TiO2 nanofibers. (b)SEM image of TiO2 nanofiber coated substrate.
gaseous byproducts from industrial productions and transporta-
tion. The detailed mechanism of photocatalytic decomposition of
VOC and NOx were described elsewhere [46–48]. Briefly, the pho-
tocatalysis of toluene and NOx mainly resulted in carbon dioxide
and HNO3, respectively.
From Fig. 2a and b, titanium nanofibrous membrane showed
21% and 30% removal for NOx and toluene, respectively. Com-
parison with literature data has been difficult due to variation in
testing sample preparation and model gases used [49,50]. In par-
ticular, photocatalytic reactions have been reported to be strongly
dependent on film thicknesses and amount of active material [48].
However, Maneerat et al. reported that ST-01-coated polyesternonwovens showed 49% removal of toluene under JIS protocol
[49]. It is noted, however, that the fibrous and porous structure
of our sample should lead to large surface area for adsorption and
decomposition of the model toxin. Unlike spherical-shaped TiO2
nanomaterials, the nanofibers did not show any agglomeration
among the primary particles (Fig. 1b). This entailed low produc-
tion cost in practical uses and future industrial production. While
these results implied that the TiO2 nanofibers could be effective in
air pollution abatement, their ability to reduce microbial infection
might push their potential application further.
To further enhance their anti-microbial activity, the TiO2
nanofibers were decorated with silver nanoparticles via pho-
toreduction. In so doing, aqueous-base photoreduction of silver
ion in the presence of the nanofiber suspension resulted in
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C. Srisitthiratkul et al./ Applied Surface Science 257 (2011) 8850–8856 8853
Fig. 2. Decomposition of NOx and toluene under JIS protocol. (a) TiO2 nanofibrous membrane showed 21% efficiency for the decomposition of nitrogen oxide (NOx). (b) A
similar membrane showed 30% removal of toluene.
nanosilver-decorated TiO2 nanofibers. Fig.3a reveals SEMimages of
the resulting hybrid nanofibers. It could be seen that the nanosized
silver particles were randomly distributed along the nanofibers’
surfaces. As shown in Fig. 3b, TEM image showed more clearlythat these nanosized silver particles attached onto the surface of
the nanofibers. The results implied that photoreduction of silver
ions and formation of silver nanoparticles occurred on the sur-
face of the fibers. Since independent silver nanoparticles were not
observed, it could be said that silver nanoparticles appeared only
on the nanofibers’ surfaces. Furthermore, a high magnification TEM
image in Fig. 3c revealed the spherical shape of these silver parti-
cles. By elemental mapping of silver under SEM (Fig. 3d), it could
be seen that the silver particles were homogeneously distributed
all over the coated layer. This was consistent with Fig. 3a.
The presence ofsilveron the TiO2 couldbe further corroborated.
The crystal structures presented in the TiO2 and nanosilver-decorated TiO2 nanofibers were determined by powder X-ray
diffraction or XRD method as shown in Fig. 4. The XRD pattern of
TiO2 nanofibers (Graph 4a) exhibited characteristic reflections at
2 of 25.0◦, 38.5◦, 48.2◦, 55.3◦, 63.6◦ and 75.0◦ corresponding to
(10 1), (00 4), (20 0), (10 5), (21 1)and(2 04) planesof the anatase
phase, respectively. After the photoreduction of silver ions, these
characteristic reflections remained with some additional reflec-
tions present (Graph 4b). These reflections at 38.2◦, 44.4◦ and 64.7◦
Fig. 3. Physical characteristics of nanosilver-decorated TiO2 nanofibers. (a)SEM micrograph of nanosilver-decorated TiO2 nanofibers. (b) TEMimage of nanosilver-decorated
TiO2 nanofibers. (c) High magnificationTEM image of thefibers. (d) Elementalmappingof silver by SEM. The white spotscorresponded to clusters of silverelement.
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Fig. 4. Structural characterizations by XRD. (a) XRDpattern of TiO2 nanofibers. (b)
XRD of TiO2 nanofibers after the photoreduction of silver ions.
represented (11 1), (20 0) and (22 0) planes of the face-centered
phase of silvermetal [35,36,43]. Finally, theaverage size of nanosil-
ver decorating on the fibers was calculated from FWHM to be
32nm. From these results, it could be said that the silver nanopar-ticles had been successfully deposited on the TiO2 nanofibers.
In a subsequently investigation, the antimicrobial activity of
titanium nanofibers was tested after nanosilver deposition using
agar diffusion test as shown in Fig. 5. The antimicrobial activity of
the nanofibers can be summarized in Table 1. From the table, TiO2
nanofibers showed no inhibitory zone, implying that the materi-
als comprised no antimicrobial property without UV. In contrast,
their nanosilver-decorated counterparts showed clear inhibitory
zones which expanded with the increase of nanosilver extent. The
influence of nanosilver on both Gram positive and Gram nega-
tive bacteria suggested that inclusion of nanosilver enhanced the
antimicrobial activity of the nanofibers.
Table 1
Formation of inhibitory zones.
Materials Zone of Inhibition (mm)
Staphylococcus
aureus ATCC6538
Escherichia coli
ATCC 25922
TiO2 Nanofibers 0.0 0.0
P25 0.0 0.0
1% Ag–TiO2 Nanofibers 0.8 0.5
2% Ag–TiO2 Nanofibers 0.8 0.5
5% Ag–TiO2 Nanofibers 1.5 1.0
10% Ag–TiO2 Nanofibers 1.5 1.0
In agreement with the above result, nanosized silver particles
have been shown to be potent antibacterial agents [51,52]. Their
antibacterial property correlated strongly with their sizes. Even
though the nanoparticles could directly interact and damage cell
membranes, the antibacterial activity of nanosilver was usually
explained in terms of the interaction between the cell membranes
and silver ions, which released from the surface. Since particles’
surface area increasedwith the decrease in diameter, smaller silver
particles tended to show more potent antibacterial activity.
Silvernanoparticles mightnot only affectthe antibacterial char-
acteristics, but also influence the photocatalytic performance of TiO2. To further understand the roles of nanosilver-decorated TiO2
nanofibers as photocatalysts, the photodegradation of methylene
blue (MB) was carried out as shown in Fig. 6. As illustrated, C 0and C were the initial concentration of MB and that after a given
period of UV lightirradiation, respectively. For all nanofibroussam-
ples and P25 as a reference, the concentration of MB decreased
with time. While deposition of nanosilver influenced the pho-
tocatalytic performances, 2% and 10% nanosilver-decorated TiO2
nanofibers resulted in the highest and lowest photocatalytic per-
formances, respectively. The reduction of activity in the latter
might come from high surface coverage of nanosilver on the TiO2
nanofibers. In contrast, the 2% nanosilver inclusion left the activity
Fig. 5. Agar diffusion tests. Top and bottom rows represented Gram positive and Gram negative bacteria, respectively. (a) and (b) represented TiO2 nanofibers. (c) and (d)
represented P25. (e) and (f) represented silver-decorated TiO2 nanofibers.
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Fig. 6. Photodegradation of methylene blue (MB). As illustrated, C 0 and C were the
initial concentrations of MB and that after a given period of UV light irradiation,
respectively.
significantly enhanced. Nanostructured silver had been known to
act as an electron trapping site which reduced the electron–holerecombination rates and, thus,improved the photocatalytic perfor-
mance of TiO2 [38,53]. It was assumed herein that nanosilver also
behaved as such and the recombination rate in the 2% nanosilver
sample was reduced.
To strengthen this assumption, the electron–hole recom-
bination rate of each sample was indirectly monitored from
their photoluminescence (PL). The correlation between the
electron–holerecombinationrate and photoluminescence in a pho-
tocatalytic sample couldbe foundelsewhere[54]. Inshort,themore
electron–hole recombination rate, the more photoluminescence.
As illustrated in Fig. 7, PL intensity decreased with the increase
of nanosilver deposition. The results were consistent with the
assumption that nanosilver acted as electron trapping sites where
the interface between nanosilver and TiO2 formed heterojunctions
[53]. Increasing the amount of nanosilver on TiO2 nanofibers’ sur-
face subsequently increased heterojunctions between these two
entities [55]. Hence, the electron–hole recombination on the tita-
nium dioxide nanofibers’ surfaces was reduced, giving rise to a
weaker PL signal in the more heavily nanosilver-decorated sam-
ples. From the MB degradation and PL measurement, it could be
summarized that, in low density, nanosilver helped improve the
performance of the nanofibers. However, in high surface cover-
age, silver might downgrade the efficiency of the photocatalyst.
From these results, it could be said that silver nanoparticles not
Fig. 7. Photoluminescence (PL) intensity as a function of nanosilver extent.
Fig. 8. Static contact angles, s, as a function of UV irradiation time. (Inset) Water
dropletson P25,TiO2 nanofibrous and nanosilver-decorated TiO2 nanofibrouslayers
were shown on thetop, middle andbottom series, respectively.
only imparted the antibacterial characteristics, but also influenced
the photocatalytic performance of TiO2
.
While the antibacterial and photocatalytic activities were cru-
cial for nanofiltration applications, the interfacial properties might
play a significant role during maintenance processes. From the
above rationale, interfacial phenomena on the nanofiber coated
layers were unveiled by contact angle measurements to exam-
ine their wetting characteristics. Static contact angles, s, were
recorded after a given interval of UV irradiation. Shown in Fig. 8,
the static contact angles of both TiO2 and nanosilver-decorated
TiO2 nanofibrous layers decreased as a function of UV irradiation
time. Those of P25 were given as a reference. At 0 h, or without any
UV irradiation, the TiO2 and nanosilver-decoratedTiO2 nanofibrous
layers showed contact angles of 38.7◦ and 27.8◦, respectively. The
latter result implied that nanosilver imparted hydrophilicity onto
the TiO2 nanofibers. After 1 h of UV irradiation, the contact angles
of both layers decreased substantially. Furthermore, after 4h of UV irradiation, both layers showed superhydrophilicity with static
contact angles around and less than 10.0◦. In such condition, it was
observed that water droplets spread rapidly on the surface of the
membranes. It was strongly believed that this result would be use-
ful in maintenance of the membrane when used in nanofiltration
applications.
5. Conclusions
The potential use of nanosilver-decorated TiO2 nanofibers for
toxin decomposition with antimicrobial activity and self-cleaning
properties was investigated. TiO2 nanofibers were prepared viaan electrospinning process. Following Japan Industrial Stan-
dard (JIS) protocol, decompositions of nitrogen oxide (NOx) and
volatile organic compound (VOC) showed 21% and 30% efficiency,
respectively. The samples showed enhanced antimicrobial activ-
ity after nanosilver inclusion. Photodegradation of methylene blue
revealed that addition of 2% nanosilver significantly enhanced
the photocatalytic performances of TiO2 nanofibers. From the
photoluminescence measurements, nanosilver might play a role
in reducing electron hole recombination rate. Additionally, the
nanofibrous membranes prepared from these nanofibers showed
superhydrophilicity under UV. Finally, it is possible to apply these
hybrid nanofibers in environmental and hygienic nanofiltration,
as the self-cleaning characteristic was expected to be valuable in
maintenance processes.
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