文档库 最新最全的文档下载
当前位置:文档库 › Characterization of mesoporous nanocrystalline TiO2 photocatalysts synthesized via a sol-solvotherma

Characterization of mesoporous nanocrystalline TiO2 photocatalysts synthesized via a sol-solvotherma

Corresponding author.Fax:+852********. E-mail address:jimyu@https://www.wendangku.net/doc/c114097083.html,.hk(J.C.Yu).

synthesis[27],have been proposed to synthesize crystal-line mesoporous TiO2.Here,we report a low-tempera-ture hybrid approach of sol–gel and solvothermal to produce crystalline mesoporous TiO2without the requirement of post thermal treatment.In this ap-proach,a homogenous micelle-stabilized-TiO2sol solu-tion is?rst synthesized by the hydrolysis and co-condensation of a titanium alkoxide in the presence of a surfactant and a stabilizing agent.Subsequent solvothermal treatment of the sol solution removes the surfactant and transfers the amorphous TiO2into crystalline nanoparticles[28–30].Finally,the TiO2 nanocrystals then assemble together into a mesoporous network.

Mordant Yellow10(MY)is non-biodegradable and can accumulate in the aquatic system becoming a major source of contamination[31].Much effort has been made for the self-sensitized degradation of these dye pollutants[32–42].Most of these studies were focused on the mechanism of photosensitized destruction of azo-dyes using commercial TiO2(Degussa P-25)as a model photocatalyst.It is established that the dye self-sensitized oxidation under visible light irradiation is initiated by the injection of electrons from LOMO of light-activated dye to conduction band of TiO2.T he injected electrons at the particle surface are trapped by surface-adsorbed O2,yielding very reactive radials such as O2àd,HOO d,and HO d that lead to their degradation and ultimately to their completely mineralization to CO2.Although TiO2is not directly excited by irradia-tion during this process,the ef?ciency of dye-degrada-tion is still believed to be related to the physicochemical properties of TiO2.These properties,including size, shape and surface area,are strongly dependent on preparation methods.Very recently,we reported several preparation routes of mesoporous nanocrystalline TiO2 powders and thin-?lms[25,27,43–46],which show high activities in gas–solid photocatalytic systems under UV illumination.In the present work,the application of the large-surface-area mesoporous nanocrystaline TiO2has been extended to liquid–solid systems,where visible light was employed to induce the self-sensitized degra-dation of azo dye.Photocatalytic activity tests reveal that such mesoporous nanocrystalline TiO2is a superior photocatalyst to P-25.The effects of acid-base additives (nitric acid,deionized water,and ammonia)on the mesoporous structure and the photocatalytic activity of samples are also described.

2.Experimental

2.1.Synthesis

All reagents were purchased from Aldrich.Titanium tetraisopropoxide(TTIP)was used as a titanium precursor.A surfactant Pluronics triblock copolymer (HO(CH2CH2O)20(CH2CH-(CH3)O)70(CH2CH2O)20H, P123,MW?5800)was used as the structural-directing agent,and a complexing agent acetylacetone(Hacac) was used to control the hydrolysis and condensation reactions of the precursor.In a typical synthesis, titanium tetraisopropoxide was added dropwise to an absolute ethanol solution of P123and Hacac under stirring.A10%nitric acid was then added to the mixture.The molar ratios of the ingredients were: titanium precursor/P123/acac/10%nitric acid/ ethanol?1:0.05:0.5:1.5:43.The?nal solution(pH is about3)was stirred for24h at room temperature.The resulting sol was placed in a100mL Te?on-lined stainless steel autoclave,which was then put in an oven for solvothermal treatment at801C for18h and then 1501C for20h.The white slurry obtained was centrifuged and washed with ethanol and water.Finally the sample was dried in a vacuum oven at1001C under vacuum.This sample was denoted as sample HT-1. Sample HT-2and HT-3were prepared by the same procedure,but the nitric acid was replaced by deionized water and10%ammonia,respectively.The pH values of the resulting solutions were6and9.

2.2.Characterization

The Brunauer–Emmett–Teller(BET)surface area (S BET)and pore size distribution were determined by using a Micromeritics ASAP2010nitrogen adsorption apparatus.All the samples were degassed at1801C prior to BETmeasurements.Wide-angle XRD patterns were obtained on a Bruker D8Advance X-ray diffractometer with Cu-K a radiation at a scanning rate of0.0212y Sà1. The accelerating voltage and the applied current were 40kV and40mA,respectively.The crystallite size was calculated from X-ray line broadening by the Scherer equation:D?0:89l=b cos y;where D is the crystal size in nm,l is the Cu-K a wavelength(0.15406),b is the half-width of the peak in rad,and y is the corresponding diffraction angle.Low-angle XRD patterns were col-lected on the same diffractometer in y2y mode at a scanning rate of0.00212y Sà1.Raman spectra of the powder samples on a glass slide were measured using a Renishaw1000micro-Raman system.Objectives of50 times magni?cation were selected.The excitation source was an Argon ion laser operating at514.5nm with an output power of20mW.Infrared(IR)spectra of the samples mixed with KBr were recorded on a Nicolet Magna560FTIR spectrometer at a resolution of 4cmà1.The concentration of the samples was kept at around0.5%.TEM images were taken on a Philips CM-120electron microscopy instrument.HRTEM images were taken on a high-resolution transmission electron microscopy system(JEOL2010F)at an accelerating voltage of200kV.A suspension in ethanol was

L.Wu et al./Journal of Solid State Chemistry178(2005)321–328 322

sonicated,and a drop was dropped on the support ?lm.The powder particles were then supported on a carbon ?lm coated on a 3mm diameter ?ne-mesh copper grid.X-ray photoelectron spectroscopy (XPS)measurements were done with a PHI Quantum 2000XPS system with a monochromatic Al-K a source and a charge neutralizer;all the binding energies were referenced to the C1s peak at 284.8eV of the surface adventitious carbon.2.3.Photocatalytic activity test

Photocatalytic activities of the samples were measured by the decomposition of MY in an aqueous solution.Air was bubbled into the solution throughout the entire experiment.A 300W tungsten halogen lamp was positioned inside a cylindrical Pyrex vessel and sur-rounded by a circulating water jacket (Pyrex)to cool it.A cutoff ?lter was placed outside the Pyrex jacket to completely remove all wavelengths less than 400nm to secure the irradiation with visible light only.0.1g of photocatalyst was suspended in a 100mL aqueous solution of 1.5?10à4M MY.Prior to irradiation,the suspensions were magnetically stirred in the dark for 1h to ensure the establishment of an adsorption/desorption equilibrium among the photocatalyst,MY and atmo-spheric oxygen.At given irradiation time intervals,4mL of the suspensions were collected,then centrifuged,and ?ltered through a Millipore ?lter (pore size,0.22in)to remove the photocatalyst particles.The degraded MY solutions were analyzed by a Varian Cary 100Scan UV-Visible spectrophotometer and the absorption peak at 355nm was monitored.The structure of MY is shown below:

OH COONa

NaO 3S

N

N

C. I. Mordant Yellow 10 (MY)

3.Results and discussion

3.1.Nitrogen adsorption and XRD analysis

Fig.1shows the N 2-sorption isotherms (inset)of the samples with their corresponding pore size distribution curves calculated from the desorption branch of the N 2-sorption isotherms by the BJH (Barrett–Joyner–Halen-da)method.Clear hysteresis loops at high relative pressure are observed.The sharp decline in the desorption curves is an indication of mesoporosity.The pore-size distribution plot shows that HT-1exhibits a mean pore diameter of 4.4nm with a narrow distribution (FWHM ?2nm).This narrow pore size

distribution is also observed for HT-2,but with a slightly increased pore size (6.7nm,FWHM ?5nm).However,sample HT-3prepared in the ammonia medium has a much larger average pore size of 10.6nm and a broad pore size distribution (FWHM ?10nm).The BET surface area,pore size,and pore volume of the prepared samples are summar-ized in Table 1.The surface areas of HT-1,HT-2and HT-3are 205,185and 116m 2g à1,respectively.These,together with the pore size distributions,indicate that acid-base medium signi?cantly affects the mesoporous structure properties of the samples.The mesoporous TiO 2prepared using the sol-solvothermal method have high surface area and pore volume,which provides more surface active sites and pore-channels for the chemisorp-tion and diffusion of reactants.

The mesoporous structure of the samples is also con?rmed by the low angle XRD patterns.As shown in Fig.2b ,only one broad peak at about 11is observed for HT-1,indicating the existence of worm-like mesoporous structure in the sample.For HT-2and HT-3,the peak becomes broad and weak,and shifts to a higher 2y angle.This means that the mesoporous structure is poorly formed in the media of higher pH.These results are consistent with literature reports that mesoporous TiO 2is better formed in acidic medium [20,46].The wide XRD patterns (Fig.2a )of the three samples give ?ve distinctive TiO 2peaks at 25.31,37.91,48.01,54.61and 62.81,corresponding to anatase (101),(103,004and 112),(200),(105and 211),(204)crystal planes (JCPDS 21-1272),respectively.These results indicate that all samples prepared by the sol-solvothermal method are pure anatase,the most photocatalytically active form of TiO 2.The average crystallite sizes estimated form the FWHM of the (101)peak are 7.0,7.4and 12.3nm for HT-1,HT-2and HT-3,respectively.3.2.Spectroscopy analysis

Raman spectra were recorded to identify the phase composition.A comparison of Raman spectroscopy with X-ray diffraction can be used to estimate the difference between the surface and bulk compositions of TiO 2powders because an exciting energy in the near IR region is less penetrating than X-rays [47].There are three phase structures for titanium dioxide.Anatase is tetragonal (I 41=amd )with four formula units per unit cell and six Raman active modes (A 1g +2B 1g +3E g ).Rutile (tetragonal,P 42=mnm )has two units and four Raman active modes (A 1g +B 1g +B 2g +E g ).Brookite is orthorhombic (Pcab)with eight formula units per unit cell,and it shows 36Raman active modes (9A 1g +9B 1g +9B 2g +9B 3g )[48].

The Raman spectra of the samples are shown in Fig.3a .Five peaks can be observed:a sharp peak at 146cm à1(but 144cm à1for HT-3),three wide mid-

L.Wu et al./Journal of Solid State Chemistry 178(2005)321–328

323

intensity peaks at 396,514,and 638cm à1and a weak peak at 198cm à1.The three bands at 638,198,and 146cm à1are assigned to the E g modes and the band at 396cm à1to the B 1g mode of the TiO 2anatase phase.The band at 514cm à1is a doublet of A 1g and B 1g modes.These observations are similar to those reported in the literature [48,49].From Fig.3b ,it can clearly be seen that the Raman peaks of HT-1and HT-2at 146cm à1are blue shifted by 2cm à1as compared with that of HT-3,which is identical to the Raman band of bulk TiO 2.To examine whether the template was completely removed and to detect the presence of surface species in the prepared samples,FTIR spectra of the samples were recorded in the range of 900–4000cm à1.Fig.4shows that two absorption peaks are present,one at 3420cm à1and the other at 1630cm à1.These correspond to the surface-adsorbed water and oxygen species [50,51].Small characteristic CO 2peaks at 2360and 2337cm à1are also observed.There is no trace of residual organic species,nitrate or ammonia ions,indicating that the

prepared mesoporous TiO 2samples are free of impurity.The three spectra are virtually identical.3.3.TEM and HRTEM images

The TEM and HRTEM images of the three samples are shown in Fig.5.The representative TEM images (Fig.5a,c and e )of HT-1,HT-2,and HT-3reveal that the samples are mesoporous without a long-range order.The mesoporosity is mainly due to the interparticle porosity.These are consistent with the nitrogen adsorp-tion and low-angle XRD results.The average diameters of the particles,estimated from the TEM images of the three samples,are in good agreement with that calculated from XRD patterns using the Scherrer equation.The selected area electron diffraction patterns in the inset of Fig.5a,c and e also con?rm that the three mesoporous TiO 2samples are polycrystalline anatase.Fig.5b,d and f are the corresponding HRTEM images of the three mesoporous TiO 2samples.They show clear

0.00

0.02

0.04

0.06

0.08

0.10

0.12

d V /d D (c m 3g -1n m -1

)

Pore Diameter (nm)

Fig.1.N 2adsorption–desorption isotherms (inset)and BJH pore size distributions;&:sample HT-1,D :sample HT-2,

J :

sample HT-3.

Table 1

Summary of the physicochemical properties of the prepared samples Sample pH S BET (m 2g à1)a Total pore volume b (cm 3g à1)Mean pore size c (nm)Crystal size d (nm)HT-132050.28 4.47.0HT-261850.34 6.77.4HT-3

9

116

0.35

10.6

12.3

a BETsurface area calculated from the linear part of the BETplot.b

Single point total pore volume of pores at P =P 0?0:97:c

Estimated using the BJH desorption branch of the isotherm.d

Calculated by the Scherrer equation.

L.Wu et al./Journal of Solid State Chemistry 178(2005)321–328

324

lattice fringes,which allow for the identi?cation of crystallographic spacing.The fringes of d ?0:34nm match that of the (101)crystallographic plane of anatase.Based on the above results,it is evident that nanocrystalline TiO 2with wormhole mesoporous struc-ture have been successfully prepared by the sol-solvothermal method.Such wormhole structure with three-dimensionally interconnected but aperiodic pore channels would facilitate the accessibility of reactants to the active sites within the mesoarchitecture [52–54].This is an attractive feature for heterogeneous catalysis.3.4.XPS spectroscopy

X-ray photoelectron spectroscopy (XPS)measure-ments were carried out to determine the surface chemical composition and the oxidation states of the elements in the samples.Fig.6a shows the XPS survey spectra of the TiO 2samples.It can be observed that all three samples contain only Ti,O,and C elements.The photoelectron peak for Ti 2p appears clearly at a binding energy 458.7eV,O 1s at 530eV and C 1s at 284.8eV.The peak positions are in agreement with the literature values [55].Fig.6b shows the high-resolution

XPS spectra of Ti 2p :The spin–orbit components (2p 3=2and 2p 1=2)of the Ti 2p peak are well deconvoluted by two curves at approximately 458.7and 464.5eV,

203040506070

(a)

HT-3

HT-2HT-1

2 Theta

12345

HT-1

HT-2

(b)

HT-3

2 Theta

Fig.2.Wide angle (a)and low angle (b)XRD patterns of HT-1,HT-2and

HT-3.

(b)

100200

300

400

500

600

700

800

900

(a)

A 2g

B 1g

B 1g

E g

E g

E g

HT-3

HT-2HT-1Wavenumber (cm -1)

Raman Shift (cm -1)

Fig.3.(a)Micro-Raman spectra of HT-1,HT-2and HT-3;(b)the enlarged patterns over the range of 80–220wavenumbers.

4000350030002500200015001000

HT-3

HT-2

HT-1

Wavenumber (cm -1)

Fig.4.FT-IR spectra of HT-1,HT-2and HT-3.

L.Wu et al./Journal of Solid State Chemistry 178(2005)321–328

325

corresponding to Ti 4+in a tetragonal structure,con-sistent with that of TiO 2powders.Fig.6c shows the high-resolution XPS spectra of O1s of the three samples.The regions of XPS spectra are composed of a narrow peak with a binding energy of ca.530.0eV and a broad peak with a binding energy of ca.531.1eV.The peaks with 530.0and 531.1eV can be respectively attributed to the Ti–O in TiO 2and hydroxyl groups chemisorbed on the surface of the samples [45,56].The contributions of OH groups in O1s on the three samples are about 25%.We may thus conclude that the three samples prepared by the sol-solvothermal method at pH values of 3,6,9possess almost the same amounts of surface hydroxyl groups.

3.5.Photocatalytic activity

Photocatalytic activity tests were conducted by the self-sensitized degradation of azo dye MY in aqueous solution under visible light irradiation.Fig.7a shows the UV-VIS spectra of MY in the present of sample HT-1.MY shows a maximum absorption at 355nm.The absorption peak gradually diminishes upon the visible light irradiation,illustrating the MY degradation.The concentrations of MY with irradiation time for the three samples and P-25are shown in Fig.7b .It is clearly observed that all three samples possess higher photocatalytic activity than P-25.This indicates that the activities of the mesoporous TiO 2samples prepared by the sol-solvothermal route are superior to that of the commercial TiO 2P-25in the dye self-sensitized degradation.HT-1is obviously the most

Fig.5.TEM and HRTEM images:(a)and (b)for HT-1,(c)and (d)for HT-2,(e)and (f)for HT-3.Insets are the corresponding electron diffraction patterns.

900800700600500400300200100

Binding Energy (eV)

O1s

Ti2p

HT-3

HT-2

(a)

Ti2s

C1s HT-1

470

468

466

464462

460458456

454

452

HT-3

Binding Energy (eV)

HT-2

(b)

Ti 2p

HT-1

Ti 2p 1/2

Ti 2p 3/2

534

532

530

528

526

HT-3

Binding Energy (eV)

HT-2

(c)

O 1s

Fig.6.XPS and high-resolution XPS spectra of HT-1,HT-2and HT-3:(a)survey,(b)titanium,(c)oxygen.

L.Wu et al./Journal of Solid State Chemistry 178(2005)321–328

326

active sample,and the order of photocatalytic activities is HT-14HT-24HT-3.

As shown in Fig.8,the mechanism of the dye self-sensitization degradation under visible light radiation is different from that under UV illumination [32–42].T he valence electrons of TiO 2are not excited by visible light as TiO 2has an absorption threshold of 385nm.Upon visible light illumination,the chemisorbed MY dye is excited to speci?c singlet or triplet states (MY ads *).Charge is then injected from the singlet or triplet excited states of the dye into the conduction band of the

mesoporous TiO 2,whereas the dye is converted to its cationic radical (MY ads +d ).The injected electron,

TiO 2(e à

),can reduce surface chemisorbed oxidants,usually O 2,to yield strong oxidizing species (such as O 2àd ,HO 2d ,OH d and so on).These radicals can destroy the organic pollutants by photooxidation (Eqs.(1)–(7)).Even though TiO 2itself is not excited in this process,it still plays an important role in electron-transfer and surface chemisorption:MY ads th n !MY ?ads ;

(1)MY ?ads tTiO 2!MY tads d tTiO 2ee àT;(2)TiO 2ee àcb TtO 2!O à2d ;(3)O à2d tH t!OOH d ;

(4)OOH d tO à2d tH t!O 2tH 2O 2;

(5)H 2O 2tO à2d !OH d tOH àtO 2;(6)

MY tads d teOH d ;O à2d ;and O 2T!!degraded products :

(7)

The three samples prepared in different acidic levels have the same phase structure and surface adsorbed oxygen species,but different surface area and particle size.Therefore,the difference in the activity of the mesoporous TiO 2samples is related to their surface areas and particle sizes.Small particle size not only produces high surface area but also shortens the route on which an electron from the conduction band of the mesoporous TiO 2migrates to its surface.Moreover,a high surface area of the mesoporous TiO 2can provide more active sites and adsorb more reactive species.Since the sample HT-1has the highest surface area and the smallest crystallite size among the three samples,it exhibits the highest photocatalytic activity.

4.Conclusions

Mesoporous nanocrystalline TiO 2photocatalysts have been prepared via a sol-solvothermal route.The characterization results show that mesoporous struc-tures of the prepared samples consist of interparticle porosity and are most effectively formed in the acidic medium.The mesoporous TiO 2samples also exhibit much higher photocatalytic activities than the commer-cial P-25in the self-sensitized degradation of azo dye MY in aqueous solution under visible light irradiation.

2

1

3

45

(b)C /C 0

Irradiation Time (hours)

(a)

A b s o r b a n c e

Wavelength

Fig.7.(a)Temporal absorption spectral patterns of MY during the photodegradation process for HT-1,(b)MY reduction in UV-vis absorption spectra at 355nm as a function of visible-light irradiation time in the prepared samples and P-25.

Mesoporous TiO 2

Fig.8.Electron-transfer processes subsequent to excitation of MY.

L.Wu et al./Journal of Solid State Chemistry 178(2005)321–328

327

Acknowledgments

The work was substantially supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No. 402904).We thank Mr.Tzekin Cheung of the Hong Kong University of Science and Technology for the HRTEM measurements.

References

[1]K.Honda,A.Fujishima,Nature238(1972)37.

[2]M.R.Hoffmann,S.T.Martin,W.Choi, D.W.Bahnemann,

Chem.Rev.95(1995)69.

[3]A.Fujishima,T.N.Rao,D.A.Tryk,J.Photochem.Photobiol.C

1(2000)1.

[4]L.Linsebigler,G.Lu,J.T.Yates Jr.,Chem.Rev.95(1995)735.

[5]A.Fujishima,K.Hashimoto,T.Watanabe,Photocatalysis

Fundamentals and Applications,?rst ed.,BKC,Tokyo,1999. [6]M.Kaneko,I.Okura,Photocatalysis,Science and Technology,

Springer,Berlin,2002.

[7]N.Serpone, E.Pelizzetti,Photocatalysis:Fundamentals and

Applications,Wiley,New York,1989.

[8]D.F.Ollis,H.Al-Ekabi,Photocatalytic Puri?cation and Treat-

ment of Water and Air,Elsevier,Amsterdam,1993.

[9]M.A.Fox,M.T.Dulay,Chem.Rev.93(1993)341.

[10]https://www.wendangku.net/doc/c114097083.html,ls,R.H.Davies,D.Worsley,Chem.Soc.Rev.22(1993)

417.

[11]A.Hagfeldt,M.Gratzel,Chem.Rev.95(1995)49.

[12]Z.Zhang,C.C.Wang,R.Zakaria,J.Y.Ying,J.Phys.Chem.102

(1998)10871.

[13]L.Yeung,S.T.Yau, A.J.Maira,J.M.Coronado,J.Soria,

P.L.Yue,J.Catal.219(2003)107.

[14]C.B.Almquist,P.Biswas,J.Catal.212(2002)145.

[15]D.M.Antonelli,J.Y.Ying,Angew.Chem.Int.Ed.Engl.34

(1995)2014.

[16]P.Yang,D.Zhao,D.I.Margoles,B.F.Chmelka,G.D.Stucky,

Nature396(1998)152.

[17]P.Yang,D.Zhao,D.I.Margoles,B.F.Chmelka,G.D.Stucky,

Chem.Mater.11(1999)2813.

[18]E.L.Crepaldi,G.J.A.A.Soler-Illia, D.Crosso, F.Cagnol,

F.Ribot,C.Sanchez,J.Am.Chem.Soc.125(2003)9770.

[19]H.Fujii,M.Ohtaki,K.Eguchi,J.Am.Chem.Soc.120(1998)

6832.

[20]S.Y.Choi,M.Mamak,N.Coombs,N.Chopra,G.A.Ozin,Adv.

Funct.Mater.14(2004)335.

[21]G.J.A.A.Soler-Illia,C.Sanchez,B.Lebeau,J.Patarin,Chem.

Rev.102(2002)4093.

[22]G.J.A.A.Soler-Illia, A.Louis, C.Sanchez,Chem.Mater.14

(2002)750.

[23]Y.Wang,X.Tang,L.Yin,W.Huang,Y.R.Hacochen,

A.Gedanken,Adv.Mater.12(2000)1183.

[24]H.Luo,C.Wang,Y.Yan,Chem.Mater.15(2003)3841.

[25]L.Z.Zhang,J.C.Yu,https://www.wendangku.net/doc/c114097083.html,mun.(2003)1942.[26]Y.Yue,Z.Gao,https://www.wendangku.net/doc/c114097083.html,mun.(2000)1755.

[27]J.C.Yu,L.Z.Zhang,J.G.Yu,Chem.Mater.14(2002)4647.

[28]M.Andersson,L.Osterlund,S.Ljungstrom, A.Palmqvist,

J.Phys.Chem.B106(2002)10674.

[29]J.C.Yu,L.Wu,J.Lin,P.S.Li,Q.Li,https://www.wendangku.net/doc/c114097083.html,mun.(2003)

1552.

[30]M.M.Wu,G.Lin,D.H.Chen,G.G.Wang,D.He,S.H.Feng,

R.R.Xu,Chem.Mater.14(2002)1974.

[31]J.He,W.Ma,J.He,J.Zhao,J.C.Yu,Appl.Catal.B:

Environmental39(2002)211.

[32]K.Vinodgopal,P.V.Kamat,Environ.Sci.Technol.29(1995)

841.

[33]K.Vinodgopal,P.V.Kamat,J.Phys.Chem.96(1992)5053.

[34]C.Nasr,K.Vinodgopal,L.Fisher,S.Hotchandani,

A.K.Chattopadhyay,P.V.Kamat,J.Phys.Chem.100(1996)

8436.

[35]F.Zhang,J.Zhao,T.Shen,H.Hidaka,E.Pelizzetti,N.Serpone,

Appl.Catal.B:Environmental15(1998)147.

[36]G.Liu,T.Wu,J.Zhao,H.Hidaka,N.Serpone,Environ.Sci.

Technol.33(1999)2081.

[37]T.Wu,G.Liu,J.Zhao,H.Hidaka,N.Serpone,J.Phys.Chem.B

103(1999)4862.

[38]T.Wu,T.Lin,J.Zhao,H.Hidaka,N.Serpone,Environ.Sci.

Technol.33(1999)1379.

[39]J.Bandara,J.Kiwi,New J.Chem.23(1999)717.

[40]L.Lucarelli,V.Nadtochenko,J.Kiwi,Langmuir16(2000)

1102.

[41]J.Bandara,J.A.Mielczarski,J.Kiwi,Langmuir15(1999)

7670.

[42]M.Stylidi, D.I.Kondarides,X.E.Verykios,Appl.Catal.B:

Environmental47(2004)189.

[43]J.G.Yu,J.C.Yu,M.K.P.Leung,W.K.Ho,B.Cheng,X.J.Zhao,

J.C.Zhao,J.Catal.217(2003)69.

[44]J.C.Yu,L.Z.Zhang,J.G.Yu,New J.Chem.26(2002)416.

[45]J.C.Yu,J.G.Yu,J.C.Zhao,Appl.Catal.B36(2002)31.

[46]J.C.Yu,X.C.Wang,X.Z.Fu,Chem.Mater.16(2004)1523.

[47]G.Busca,G.Ramis,J.M.G.Amores,V.S.Escribano,P.Piaggio,

J.Chem.Soc.Faraday Trans.90(1994)3181.

[48]A.Brioude,F.Lequevre,J.Mugnier,J.Dumas,G.Guiraud,

J.C.Plenet,J.Appl.Phys.88(2000)6187.

[49]D.Bersani,P.P.Lottici,X.Z.Ding,Appl.Phys.Lett.72(1998)

73.

[50]L.Wu,J.C.Yu,L.Z.Zhang,X.C.Wang,W.K.Ho,J.Solid State

Chem.177(2004)2584.

[51]Z.Ding,G.Q.Lu,P.F.Green?eld,J.Phys.Chem.B104(2000)

4815.

[52]D.R.Rolison,Science299(2003)1698.

[53]T.R.Pauly,Y.Liu,T.J.Pinnavaia,S.T.L.Billinge,T.P.Rieker,

J.Am.Chem.Soc.121(1999)8835.

[54]R.T.Yang,T.J.Pinnavaia,W.Li,W.Zhang,J.Catal.172(1997)

488.

[55]J.F.Moulder,W.F.Stickle,P.E.Sobol,K.D.Bomben,Hand-

book of X-ray Photoelectron Spectroscopy,Perkin Elmer Corp., Eden Prairie,MN,1992.

[56]J.C.Yu,J.G.Yu,H.Y.Tang,L.Z.Zhang,J.Mater.Chem.12

(2002)81.

L.Wu et al./Journal of Solid State Chemistry178(2005)321–328 328

相关文档
相关文档
最新文档