mb,

ivera

Received 22 January 2010Accepted 2 May 2010Available online 19 May 2010

Keywords:A. Polymermatrix composites (PMCs)

uoropolymer nanober mats with carboxyl groups were prepared by electrospinning, and then tita-

photocatalytic efciency under natural sunlight, easy agglomerat-ing and losing in the using.

Immobilization of semiconductor particles on the carrier isone of the best effective methods to prevent the agglomeratingand losing of semiconductor particles in using [4]. The semicon-

2

under hydrothermal conditions is a convent way [10].In this paper we demonstrate a novel method to prepare visi-

ble-light photocatalytic activity TiO2ZnS particles loaded by u-oropolymer electrospun ber with carboxyl groups underhydrothermal condition. The photocatalytic activity and stabilitywere investigated through degradation of methylene blue usingTiO2ZnS/uoropolymer ber composites as photocatalyst undervisible-light radiation. The results show the as-prepared compos-ites have good visible-light photocatalytic activity and stabilityfor the potential applicability in environmental remediation.

* Corresponding author. Tel./fax: +86 551 2901455.** Corresponding author. Tel.: +1 270 7452221.

E-mail addresses: xwb105105@sina.com (W. Xu), wei-ping.pan@wku.edu (W.-P.

Composites Science and Technology 70 (2010) 14691475

Contents lists availab

Composites Science

evPan).Growing concerns over the threat of chemical warfare agentsand exposure to toxic industrial chemicals have drawn muchattention to the challenge of developing new harmless treatmentmethods for the toxic organic materials [1]. Photocatalytic degra-dation of harmful organic pollutants in the air and the water usingsemiconductor particles, such as titanium dioxide (TiO2), is one ofthe most widely studied methods [2]. The semiconductor particlesare able to convert abundant solar energy into effective chemicalenergy, and mineralized the organic pollutants completely [3].However, the photocatalytic degradation of toxic organic pollu-tants using semiconductor is still challenged, in terms of the low

bers are also used to prepare photocatalytic materials [5].However, polymers usually have troubles in compounding withinorganic powders, and easy are degraded in the photocatalyticprocess [6]. Fluoropolymers like poly(vinylidene diuoride)(PVDF), which has excellent weather, radiation, chemical andthermal resistance due to stable CF bond in the main chain[7]. The uoropolymers electrospun ber mats with micro-sizedporous structure [8] are able to offer high specic area and goodenrichment ability for organic compounds, are suitable as photo-catalyst carrier [9]. The visible-light photocatalytic activity of sol-itary TiO2 is able to improved greatly by doping it with otherelements, and the synthesis of nanocrystalline TiO capped ZnSB. SynergismD. Scanning/transmission electronmicroscopy (STEM)D. Thermo-gravimetric analysis (TGA)E. Electro-spinning

1. Introduction0266-3538/$ - see front matter 2010 Elsevier Ltd. Adoi:10.1016/j.compscitech.2010.05.001nium and zinc ions were introduced onto the ber surfaces by the coordinating of carboxyl of uoro-polymer in solution. The TiO2ZnS composites with diameters 15 nm to 1 lm were immobilized onthe surface of uoropolymer electrospun ber using hydrothermal synthesis. The Fourier transforminfrared spectroscopy and X-ray photoelectron spectroscopy analysis reveal that some chemical interac-tion exists between TiO2ZnS composites and uoropolymer bers, so the semiconductor compositeswere immobilized tightly on the surface of uoropolymer bers. The ultravioletvisible absorption spec-tra show the TiO2ZnS/uoropolymer ber composites have low band gap and good visible-lightresponse ability. The degradation rate of methylene blue in TiO2ZnS/uoropolymer ber compositessystem was considerably higher than that of TiO2 or TiO2ZnS nanoparticles system under visible-lightirradiation, because the TiO2ZnS/uoropolymer ber composites possess good visible-light responseability, high specic surface areas, and adsorptionmigrationphotodegradation process. The photocat-alytic activity of TiO2ZnS/uoropolymer ber composites changes indistinctively after 10 repeatingphotocatalysis tests.

2010 Elsevier Ltd. All rights reserved.

ductor particles directly depositing onto polymer electrospun -Article history: The preparation and photocatalysis of TiO2ZnS/uoropolymer ber composites were investigated. TheVisible-light photocatalytic activity of seby electrospun ber

Tieshi He a,c, Zhengfa Zhou a, Weibing Xu a,*, Yan Caoa School of Chemical Engineering, Hefei University of Technology, Hefei 230009, Chinab Institute for Combustion Science and Environmental Technology, Western Kentucky Unc Liaoning Key Laboratory of Applied Chemistry, Bohai University, Jinzhou 121000, Chin

a r t i c l e i n f o a b s t r a c t

journal homepage: www.elsll rights reserved.iconductor composites supported

Zhifeng Shi a, Wei-Ping Pan b,**

sity, Bowling Green, 42101, USA

le at ScienceDirect

and Technology

ier .com/ locate/compsci tech

2. Experimental

Triuoroethyl acrylate (TFA) was obtained from Xuejia Fluo-rine-silicon Chemical Co., Ltd, Harbin China. Anatase Degussa P25was purchased from Shanghai Haiyi Scientic & Trading Co., Ltd.Poly(vinylidene diuoride) (PVDF), titanium oxo-sulphate (TiOS-O4), methacrylic acid (MAA), zinc sulfate (ZnSO4), thioacetamide(TAA), methylene blue, urea and other chemicals were purchased stirring. The Degussa P25 and TiO2ZnS powders synthesized

TiO2 crystals, and then both semiconductor crystals decomposing

1470 T. He et al. / Composites Science and Tfrom Shanghai Chemicals Ltd., and used as received.Perkin Elmer Spectrum 100 FTIR spectrometer was used to

widely scan the synthetic products. JSM-6700F scanning electronmicroscopy (SEM) was utilized to study the surface morphologiesof the products. The specic surface area (BET) analyzed by ASAP2020 M + C. ESCALAB 250 X-ray photoelectron spectroscopy (XPS)was used to study the structure of composites. Transmission elec-tron microscope (TEM) image and the selected area electron dif-fraction (SAED) pattern were taken on JEOL 2010. The crystalstructure was detected through the X-ray diffraction (XRD), RigakuD/max-rB. The thermo-gravimetric analysis (TGA), Netzsch TG-209-F3, was applied to estimate the weight loss of composites.Ultravioletvisible (UV/VIS) absorption spectra were obtained ona Shimadzu Solidspec-3700 DUV spectrophotometer at roomtemperature.

The synthesis of MAATFA random copolymers was performedin an automated reactor system. 30 g MAA, 70 g TFA, and 0.5 g 2,2-azobisisobutyronitrile (AIBN) were added into a three-neckedask capacity 250 mL equipped with a condenser, a stirrer and aN2 inlet. After polymerizing at 80 C for 1 h, the reaction mixturewas transferred to a stainless steel plate and placed in an oven at40 C for 12 h. Then the reaction mixture was maintained at100 C for 3 h, so that the remaining monomers can polymerize.

Poly(MAA-co-TFA)/PVDF electrospun ber mats were preparedusing a typical electrospinning process [11]. 10.3 g PVDF and1.7 g poly(MAA-co-TFA) were rst dissolved in 88 g N,N-dimethyl-formamide (DMF). The solution was electrospun at 25 kV positivevoltage, 15 cm working distance (the distance between the needletip and the target), and 1.0 mL h1 ow rate. The collection timewas set to 2.0 h. All manipulations were carried out at roomtemperature. The electrospun ber mats of uoropolymers werecut into strips of dimension 2.0 cm 2.0 cm for the followingexperiments.

The above-mentioned strip of uoropolymer electrospun bermats were immersed into 10.0 mL, 0.08 mol L1 aqueous solutionof titanium oxo-sulphate and 1.0 mL concentrated sulfuric acid ina 50 mL Teon-lined stainless steel autoclave for 6 h in order toform the complex of carboxylic of uoropolymer electrospun bersurface and titanium ion. Then 20.0 mL, 0.08 mol L1 urea and20 mL distilled water were added. Then 0.0 mL, 0.5 mL, 1.0 mL,3.0 mL, 5.0 mL, 0.01 mol L1 ZnSO4 and corresponding 0.02 mol L1

TAA were added. The reactant content of hydrothermal system wasshown in Table 1. The autoclave was sealed at 150 C for 8 h, andthen cooled to room temperature. The TiO2ZnS/uoropolymer -ber composites were washed for three times with distilled waterunder ultrasonic to remove the unreacted precursor and byprod-ucts, and dried in vacuum at 80 C for 12 h.

Table 1Reactants content of hydrothermal system.

Samples ZnSO4 (102

mol)TiOSO4 (102

mol)EDX of Zn(wt.%)

Crystallite size(nm)

TiZn0 0.0 80 0.0 5TiZn1 0.5 80 0.24 15

TiZn2 1.0 80 0.91 100TiZn3 3.0 80 4.73 200TiZn4 5.0 80 13.06 1000and combining, so the TiO2ZnS mixed crystals generated on theuoropolymer ber surface. When the zinc ion content of reactionsystem is low, the TiO2ZnS particle size is less than 100 nm be-cause of heterogeneous nucleation effect, as shown in Fig. 1c andd. With zinc ion content increase, ZnS homogeneous nucleationplays as a dominant role, plus, the nucleation and growth of ZnSparticles accelerates under hydrothermal conditions, which inhib-its instant decomposing and combining of semiconductor particles,thus semiconductor agglomerations sized over 200 nm were ob-tained, as shown in Fig. 1e and f.

3.2. Characterization of TiO2ZnS/uoropolymer ber composites

The XRD patterns and the corresponding characteristic 2h val-ues of the diffraction peaks were shown in Fig. 2. It is conrmedthat semiconductor composites as-prepared samples is identiedas anatase-phase (JCPDS card No. 21-1272), ZnS as cubic-phase(JCPDS card No. 5-566) and the typical PVDF crystal structureaccording to Stengl et al. methods [10] were performed as statedin the previous steps with electromagnetic stirring. Prior to irradi-ation, the photocatalytic reaction system was stirred in a darkcondition for 15 min to establish an adsorptiondesorption equi-librium. The photocatalytic reaction system was sampled at regu-lar intervals, and the semiconductor powders suspensions werecentrifuged before measured. The remaining methylene blue con-centration after adsorptiondesorption equilibrium (C0) and pho-todegradation (C) was detected by UV/VIS at 665 nm, and thedegradation efciency be expressed as (C/C0)%.

3. Results and discussion

3.1. Morphology of TiO2ZnS/uoropolymer ber composites

The poly(MAA-co-TFA)/PVDF electrospun ber mats were madeof random nonwoven mesh of bers, and had an interconnectedopen porous structure, as shown in Fig. 1a. The SEM images ofTiO2ZnS/uoropolymer ber composites prepared by differentproportions for 8 h at 150 C are compared in Fig. 1bf and the cor-responding Zn content of composites is presented in Table 1. Thesize distribution of semiconductor particles was about 5 nm to1 lm, and the size and agglomeration of semiconductor particleswere improved with the increasing zinc ion contents in the reac-tion system, as shown in Table 1. The reasons are able to explainedas follows: the sulde ion was released from TAA at low tempera-ture with high rate [12], but the TiO2 crystal prepared by hydro-thermal hydrolysis of titanium oxo-sulphate with urea needmulti-step reaction [13], therefore the generation and growth ofZnS crystal were faster than that of the TiO2 crystal under the samereaction system. Without zinc added, the TiO2 crystals formationand growth were controlled by carboxyl along the surface of elec-trospun ber, and the about 5 nm TiO2uoropolymer ber com-posites were achieved, as shown in Fig. 1b. With the zinc ionadded, the ZnS crystals generated on the ber surface precededPhotocatalytic degradation of methylene blue solution was per-formed by photochemical reactor (SGY-1, Stonetech Co., Ltd. Nan-jing, China), light source is 350W xenon lamp, and reaction systemtemperature was 23 1 C. The TiO2ZnS/uoropolymer ber com-posites and 300.0 mL 16.0 mg L1 methylene blue were added tothe quartz tube-500 mL. The TiO2ZnS/uoropolymer ber com-posites can be extended well in methylene blue solution without

echnology 70 (2010) 14691475[14]. Three intensity peaks only of TiO2 or ZnS have appeared inthe XRD patterns and all other high angle peaks have submergedin the background due to large line broadening. The crystal

Fig. 1. SEM images of (a) poly(MAA-co-TFA)/PVDF electrospun ber mats, and TiO2ZnS/(d) TiZn2, (e) TiZn3, (f) TiZn4.

30 40 50 60

abcd

Inte

nsity

2 Theata (Deg.)

fe

Fig. 2. XRD patterns of (a) poly(MAA-co-TFA)/PVDF electrospun ber and the TiO2ZnS/uoropolymer ber composites prepared by different reactants. (b) TiZn0, (c)TiZn1, (d) TiZn2, (e) TiZn3, (f) TiZn4.

T. He et al. / Composites Science and Technology 70 (2010) 14691475 1471structure and guration of semiconductor composites were furtherdiscussed using TEM analysis.

The TEM images of TiO2ZnS/uoropolymer ber compositesprepared by reactants TiZn2 demonstrate the slightly agglomeratedTiO2ZnS particles, which are inclusive of nanocrystallites withindistinct polygonal shape of about 100 nm in size, as shown inFig. 2a. The selected area electron diffraction (SAED) patterns of cu-bic ZnS and anatase TiO2 are shown in Fig. 3b and c.

Typical FTIR spectra of poly(MAA-co-TFA)/PVDF electrospun -ber and TiO2ZnS/uoropolymer ber composites prepared byreactants TiZn2 are compared in Fig. 4. It is evident that the poly(-MAA-co-TFA)/PVDF electrospun ber mats have peaks at 3350and 1670 cm1, corresponding to hydroxyl and carbonyl stretch-ing of the carboxyl groups of poly(MAA-co-TFA). The correspond-ing hydroxyl and carbonyl absorption peaks of TiO2ZnS/uoropolymer ber composites have been broadened and slightly

uoropolymer ber composites prepared by different reactants. (b) TiZn0, (c) TiZn1,

pre

1472 T. He et al. / Composites Science and Tshift to the lowwavenumber. This may be due to that the metal ionwas complexation adsorbed by the carboxyl on the surface of u-oropolymer electrospun [15,16], and then the semiconductor nu-clei formed and grew into compound particles on the surface ofuoropolymer ber by hydrothermal precipitation, so the chemicalinteraction exists between uoropolymer ber and semiconductorparticles.

The surface properties of TiO2ZnS/uoropolymer ber com-posites were further investigated by XPS analysis, as shown inFig. 5. The Ti2p3/2 bonding energy is 458.6 and has 0.6 eV shift

Fig. 3. TEM images of (a) TiO2ZnS/uoropolymer ber compositescompared with the typical anatase TiO2 (459.2 eV) [17], which re-sulted from the interaction between semiconductor particles anduoropolymer [18], as shown in Fig. 5a. There are peaks appearedat around 282.3 eV, 286.5 eV, 288.7 eV, in the C1s spectrum and

4000 3000 2000 2000 1500 1000 500

T / %

Wavenumbers / cm-1

3350

a

b1670

Fig. 4. FTIR spectra of (a) poly(MAA-co-TFA)/PVDF electrospun ber, (b) TiO2ZnS/uoropolymer ber composites prepared by reactants TiZn2.531.7 eV, 532.8 eV in the O1s spectrum, shown in Fig. 5b and c,and the peaks were also able to ascribe to the inuence of carboxylcoordinated with nonbonding metal ion of semiconductor [19]. Asa result, the semiconductor particles were able to immobilizetightly on the surface of uoropolymer bers.

UV/Vis spectra show the photosensitive properties of TiO2/ZnSuoropolymer ber composites. The poly(MAA-co-TFA)/PVDF elec-trospun ber mats have no evident absorption above 250 nmwavenumbers (Fig. 6a). This reveals the poly(MAA-co-TFA)/PVDFelectrospun ber mats do not disturb the light absorption of semi-

pared by reactants TiZn2, SAED of the sample (b) ZnS and (c) TiO2.

echnology 70 (2010) 14691475conductor of TiO2/ZnSuoropolymer ber composites during thephotocatalytic process. The UV/Vis absorption spectrum of theTiO2uoropolymer ber composites reects that the absorptionedge is about 382 nm, as shown in Fig. 6b. The UV/Vis absorptionedge of TiO2ZnS/uoropolymer ber composites have obviouslyshift to the long wavelength, as shown in Fig. 6cf. It is due tothe S of ZnS surface change the light absorption character ofTiO2ZnS, reduce the band gap, [20] and result in the improvementof the visible-light response ability of TiO2ZnS/uoropolymer -ber composites. When the reaction system have lower content zincion, the TiO2 crystals were compounded and mixed very well withZnS through heterogeneous nucleation, and the TiO2ZnS particleshave strong compound effect, therefore the respectively absorptionedge is about 473 nm and 450 nm, as shown in Fig. 6c and d. How-ever, with the zinc ion content of reaction system increased, theZnS agglomeration generation, and ZnS crystals were hard todecompose for TiO2 crystals combining, so the TiO2 crystals arenot capped very well with ZnS crystals, therefore the compound ef-fect reduces, the respectively absorption edge is about 402 nm and390 nm, as shown in Fig. 6e and f.

TGA curve of poly(MAA-co-TFA)/PVDF electrospun ber showsseveral thermal decomposition stages, but TiO2ZnS/uoropoly-mer ber composites prepared by TiZn2 does not show thermaldecomposition stage until 450 C, as shown in Fig. 7. This phenom-enon may be due to that the low-molecular weight substances ofpoly(MAA-co-TFA)/PVDF electrospun ber mats dissolved or fusedconnected under long-time hydrothermal condition, and the inter-action between semiconductors particles and uoropolymer bersmay also improve the thermal stability of TiO2ZnS/uoropolymer

600 400 200

S2p

C1s1s

Ti2p

) 1.5

nd T1000 800

Zn2p

0.5

1.0F

Rel

ativ

e In

tens

ity (c

psx106

a

T. He et al. / Composites Science aber composites. Semiconductor particles content of TiO2ZnS/u-oropolymer ber composites was measured though the weight lossafter uoropolymer electrospun ber was fully decomposed at700 C, and the TiO2ZnS content of TiO2ZnS/uoropolymer bercomposites calculated was 24.9%.

The specic surface area of TiO2ZnS of TiO2ZnS/uoropoly-mer ber composites prepared by TiZn2 is considerably higher thanthat of Degussa P25 and poly(MAA-co-TFA)/PVDF electrospun bermats, but is lower than that of TiO2ZnS powders, as shown in Ta-ble 2.

3.3. Photocatalytic degradation of methylene blue

Photocatalysis of TiO2ZnS/uoropolymer ber composites pre-pared by TiZn2, TiO2ZnS powders, Degussa P25, uoropolymer

Binding Ene

Inte

nsity

(cps

)

Binding Energy (eV)

C1sb

292 290 288 286 284 282 280

Fig. 5. XPS spectrum of TiO2ZnS/uoropolymer ber composit

200 400 600 800

0.0

0.4

0.8

1.2

1.6

fe

d

b

c

Wavelength nm

a

Abso

rban

ce

Fig. 6. UV/VIS absorption spectra of (a) poly(MAA-co-TFA)/PVDF electrospun bermats, and the TiO2ZnS/uoropolymer ber composites prepared by differentreactants (b) TiZn0, (c) TiZn1, (d) TiZn2, (e) TiZn3, (f) TiZn4.O1s

echnology 70 (2010) 14691475 1473electrospun ber mats and blank sample were performed for themethylene blue degradation under visible-light irradiation, asshown in Fig. 8. Near-complete degradation of methylene blue oc-curred in 120 min in the presence of TiO2ZnS/uoropolymer bercomposites, as shown in Fig. 8a. A slight change of the methylene

rgy (eV)

534 532 530 528

O1sc

Binding Energy (eV)

Inte

nsity

(cps

)

es prepared by reactants TiZn2 (a) survage, (b) C1s, (c) O1s.

200 400 6000

25

50

75

100

b

Wei

ght (

%)

Temperature ( 0C)

a

Fig. 7. Thermal gravity analytical of (a) poly(MAA-co-TFA)/PVDF electrospun bermats and (b) TiO2ZnS/uoropolymer ber composites prepared by TiZn2.

Table 2Specic surface area.

Sample SBET (m2 g1)

Degussa P25 50.0TiO2ZnS powders 115.1(MAA-co-TFA)/PVDF electrospun ber mats 37.2TiO2ZnS of TiO2ZnS/uoropolymer composites (TiZn2) 96.7

blue concentration was observed for the blank sample, as shown inFig. 8e. The remaining methylene blue is 0.01 wt.% in the presenceof TiO2ZnS/uoropolymer ber composites, and it is 75.6 wt.% inthe presence of Degussa P25 after 110 min visible-light irradiation,as shown in Fig. 8a and c. So the TiO2ZnS/uoropolymer bercomposites exhibited higher photocatalytic efciency than that ofTiO2 powder in the almost same TiO2 concentration (Table 3).The reason is that the specic surface area and visible-light re-

0 40 80 120

0

25

50

75

100edc

ba

Time (min)

C/C

0(%)

-15

Fig. 8. Photocatalytic degradation of methylene blue by (a) TiO2ZnS/uoropoly-mer ber composites prepared by TiZn2, (b) TiO2ZnS powders, (c) Degussa P25, (d)(MAA-co-TFA)/PVDF electrospun ber mats; (e) blank sample.

1474 T. He et al. / Composites Science and Tspond ability of TiO2ZnS/uoropolymer ber composites werehigher than that of Degussa P25 (Table 2). The specic surface areaof TiO2ZnS/uoropolymer ber composites prepared by TiZn2 waslower of than that of TiO2ZnS powder, as shown in Table 2, but theremaining methylene blue is 20.2 wt.% after 110 min visible-lightirradiation in the presence of TiO2ZnS powders. There may beadsorptionmigrationphotodegradation [21] exists in the photo-catalysis reaction: methylene blue was rst adsorbed onto the sur-face of uoropolymer bers because of its hydrophobicity, and

Table 3Photocatalyst concentration in solution.

Sample Photocatalyst (mg L1)

TiO2ZnS/uoropolymer ber composites (TiZn2) 34.2TiO2ZnS powders 34.7Degussa P25 35.1(MAA-co-TFA)/PVDF electrospun ber mats Blank polymermatrix nanocomposites. Compos Sci Technol 2009;69:18806.

[3] Tomonori N, Akira S, Hiroshi O. Optically excited near-surface phonons of TiO

Fig. 9. SEM image of TiO2ZnS/uoropolymer ber composites prepared by TiZn2after 10 times degradation of methylene blue solution under UV irradiation for 2.0 heach.2

(110) observed by fourth-order coherent Raman spectroscopy. J Chem Phys2009;131:0847038.

[4] Li D, Xia YN. Direct fabrication of composite and ceramic hollow nanobers byelectrospinning. Nano Lett 2004;4:9338.

[5] Jin M, Zhang XT, Nishimoto S, Liu ZY, Tryk DA, Emeline AV, et al. Light-stimulated composition conversion in TiO2 -based nanobers. J Phys Chem C2007;111:65865.

[6] Zhao Y, Zhang X, Zhai J, He J, Jiang L, Liu Z, et al. Enhanced photocatalyticactivity of hierarchically micro-/nano-porous TiO2 lms. Appl Catal B2008;83:249.

[7] KKC H, Kalinka G, Tran M. Fluorinated carbon bres and their suitability asreinforcement for uoropolymers. Compos Sci Technol 2007;67:2699706.

[8] Huang Z-M, Zhang YZ, Kotaki M, Ramakrishna S. A review on polymernanobers by electrospinning and their applications in nanocomposites.Compos Sci Technol 2003;63:222353.

[9] Huang J, Wang D, Hou H, You T. Electrospun palladium nanoparticle-loadedcarbon nanobers and their electrocatalytic activities towards hydrogenperoxide and NADH. Adv Funct Mater 2008;18:441.

[10] Stengl V, Bakardjieva S, Murafa N, Houskova V, Lang K. Visible-lightphotocatalytic activity of TiO2/ZnS nanocomposites prepared byhomogeneous hydrolysis. Microporous Mesoporous Mater 2008;110:3708.

[11] Zhou Z, He D, Xu W, Ren F, Qian Y. Preparing ZnS nanoparticles on the surfaceof carboxylic poly(vinyl alcohol) nanobers. Mater Lett 2007;61:45003.then migrated to semiconductor particles surface, nally was pho-tocatalytic degraded by semiconductor particles, so deduce theTiO2ZnS/uoropolymer ber composites possess higher photocat-alytic efciency than that of TiO2ZnS powders for the degradationof methylene blue with the same concentration.

The photocatalytic stability of TiO2ZnS/uoropolymer bercomposites prepared by TiZn2 evaluated by the degradation ofmethylene blue solution under 10 times of repeated visible-lightirradiation for 120 min. The results reveal that the photocatalyticactivity of TiO2ZnS/uoropolymer ber composites changesindistinctively. The SEM image of TiO2ZnS/uoropolymer bercomposites prepared by TiZn2 after 10 times degradation of meth-ylene blue solution shows that the semiconductor particles aretightly immobilized on the surface of uoropolymer nanobersafter the degradation tests. As a conclusion, the TiO2ZnS/uoro-polymer ber composites possess high photocatalytic stability forthe photodegradation of organic pollutants Fig. 9.

4. Conclusion

The TiO2ZnS composites with diameters from 15 nm to 1 lmwere immobilize on the surface of uoropolymer ber under differ-ent reaction system, and the chemical interaction existed betweenTiO2ZnS composites and uoropolymer bers. When themolar ra-tio of zinc ion and titanic ion in reaction systemwas 1:80, the TiO2ZnS/uoropolymer ber composites possess good visible-light pho-tocatalytic activity because of its strong visible-light responseactivity, quite high specic area and synergistic effect. The repeatedphotocatalysis tests show the TiO2ZnS/uoropolymer ber com-posites possess good visible-light photocatalytic stability.

Acknowledgments

This work is supported by the National Natural Science Founda-tion of China (20776034), Doctoral Fund of Ministry of Education ofChina (20070359036).

References

[1] Cao Y, Gao Z, Zhu J, Wang Q, Huang Y, Chiu C, et al. Impacts of halogenadditions on mercury oxidation, in a slipstream selective catalyst reduction(SCR), reactor when burning sub-bituminous coal. Environ Sci Technol2007;42:25661.

[2] Hamming LM, Qiao R, Messersmith PB, Catherine Brinson L. Effects ofdispersion and interfacial modication on the macroscale properties of TiO2

echnology 70 (2010) 14691475[12] Li Zhang LY. Hydrothermal growth of ZnS microspheres and theirtemperature-dependent luminescence properties. Cryst Res Technol2008;43:10225.

[13] Soler-Illia G, Jobbagy M, Candal RJ, Regazzoni AE. Synthesis of metal oxideparticles from aqueous media: The homogeneous alkalinization method. JDispersion Sci Technol 1998;19:20728.

[14] Wu J, Schultz JM, Yeh F, Hsiao BS, Chu B. In Situ simultaneous synchrotronsmall- and wide-angle X-ray scattering measurement of poly(vinylideneuoride) bers under deformation. Macromolecules 2000;33:176577.

[15] Drew C, Wang XY, Bruno FF, Samuelson LA, Kumar J. Electrospun polymernanobers coated with metal oxides by liquid phase deposition. ComposInterfaces 2005;11:71124.

[16] Graziola F, Girardi F, Bauer M, Di Maggio R, Rovezzi M, Bertagnolli H, et al. UV-photopolymerisation of poly(methyl methacrylate)-based inorganicorganichybrid coatings and bulk samples reinforced with methacrylate-modiedzirconium oxocluster. Polymer 2008;49:433243.

[17] Willneff EA, Braun S, Rosenthal D, Bluhm H, Havecker M, Kleimenov E, et al.Dynamic electronic structure of a Au/TiO2 catalyst under reaction conditions. JAm Chem Soc 2006;128:120523.

[18] Woan K, Pyrgiotakis G, Sigmund W. Photocatalytic carbon-nanotube-TiO2composites. Adv Mater 2009;21:22339.

[19] Shanmugasundaram S, Horst K. Daylight photocatalysis by carbon-modiedtitanium dioxide. Angew Chem Int Ed 2003;42:490811.

[20] Tao Q, Zhang Y, Zhang X, Yuan P, He H. Synthesis and characterization oflayered double hydroxides with a high aspect ratio. J Solid State Chem2006;179:70815.

[21] Matos J, Laine J, Herrmann JM. Effect of the type of activated carbons on thephotocatalytic degradation of aqueous organic pollutants by UV-irradiatedtitania. J Catal 2001;200:1020.

T. He et al. / Composites Science and Technology 70 (2010) 14691475 1475

Visible-light photocatalytic activity of semiconductor composites supported by electrospun fiberIntroductionExperimentalResults and discussionMorphology of TiO2ZnS/fluoropolymer fiber compositesCharacterization of TiO2ZnS/fluoropolymer fiber compositesPhotocatalytic degradation of methylene blue

ConclusionAcknowledgmentsReferences