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High-performance TiO 2from Baker’s yeast
Wen He a ,?,Jingjie Cui b ,e ,Yuanzheng Yue a ,c ,?,Xudong Zhang a ,?,Xi Xia d ,Hong Liu e ,Suwen Lui a
a
Shandong Key Laboratory of Glass and Ceramic,Department of Materials Science and Engineering,Shandong Institute of Light Industry,Jinan 250353,China b
School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,PR China c
Section of Chemistry,Aalborg University,DK-9000Aalborg,Denmark d
Institute of Applied Chemistry,Xinjiang University,Urumqi 830046,China e
State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,PR China
a r t i c l e i n f o Article history:
Received 1August 2010Accepted 15October 2010
Available online 21October 2010Keywords:
Mesoporous TiO 2Yeast cells
Biomimetic synthesis Catalytic activity Paper wastewater
a b s t r a c t
Based on the biomineralization assembly concept,a biomimetic approach has been developed to synthe-size high-performance mesoporous TiO 2.The key step of this approach is to apply Baker’s yeast cells as biotemplates for deriving the hierarchically ordered mesoporous anatase structure.The mechanism of formation of the yeast–TiO 2is revealed by characterizing its morphology,microstructure,and chemical composition.The yeast–TiO 2exhibits outstanding photocatalytic performance.Under visible-light irradi-ation,the removal ef?ciency of chemical oxygen demand (COD)and color of the paper industry waste-water has reached 80.3%and nearly 100%,respectively.The approach may open new vistas for fabricating advanced mesoporous materials under ambient condition.
ó2010Elsevier Inc.All rights reserved.
1.Introduction
Over the past decade,biology has had a profound in?uence on materials science and engineering [1].Numerous materials with various potential applications have been prepared via biological methods,including gold nanoparticles [2],gallium oxide [3]and conducting polyaniline (PANI)nanoparticles [4].Very recently,our previous study on biologically formed mesoporous amorphous silica,opens a potential avenue to develop highly durable meso-porous membranes at room temperature [5].
Biological systems can produce extraordinary inorganic struc-tures and morphologies [6].Hence,the creation of nanoscale mate-rials for advanced structures has led to a growing interest in the area of biomineralization [7].The process of biomineralization and assembly of the inorganic components into hierarchical,sophisticated structures has led to the development of a variety of different approaches that mimic the recognition and nucleation capabilities found in biomolecules for inorganic material synthesis [1].Compared with other fabrication processes,the advantage of the biomineralization processes is that they besides molecular
control of the structure,size,aggregation,morphology and crystal-lographic orientation of inorganic crystals,yield advanced syn-thetic materials in an environment benign system.
Baker’s yeast Saccharomyces cerevisiae is ubiquitous unicellular eukaryotic microorganism.Currently,studies on yeast cells have generated considerable scienti?c interest [8].In molecular biology research,yeast is a nearly ideal model system for eukaryotic biol-ogy at both cellular and molecular level [9].Hence,yeasts are often used for basic investigations of cellular processes and for the study of gene structure and protein function.An attractive possibility is to use Baker’s yeasts S.cerevisiae in the synthesis of inorganic materials due to its low pH tolerance,high inhibitor concentra-tions,and its ability to grow anaerobically [8].For example,Baker’s yeast S.cerevisiae has successfully been used in the synthesis of nanoparticles [10,11].Recently,by biomimetic mineralization,yeast cells with a magnetic arti?cial mineral shell have been ob-tained,which helps yeast cells to have a longer life and new prop-erties [12].
As the most well-known multifunctional material,titanium oxi-des are widely investigated in various ?elds [12–15].Currently,biocatalytic and biomimetic synthesis of TiO 2is increasing in pop-ularity,e.g.TiO 2was synthesized through a biocatalytic route [16],and the hierarchical pores were controlled using biotemplates including green leaves,bamboo inner membrane,and eggshell membrane [15,17,18].By combining layer-by-layer assembly with biomimetic mineralization to form hierarchical structures prot-amine–titania hybrid microcapsules have recently been produced [19].However,to our best knowledge,biomimetic synthesis of
0021-9797/$-see front matter ó2010Elsevier Inc.All rights reserved.doi:10.1016/j.jcis.2010.10.035
Abbreviations:COD,chemical oxygen demand;Yeast–TiO 2,hierarchically ordered mesoporous anatase TiO 2;CMC,critical micelle concentration;PIW,paper industry wastewater.
?Corresponding authors.Address:Shandong Key Laboratory of Glass and Ceramic,Department of Materials Science and Engineering,Shandong Institute of Light Industry,Jinan 250353,China (Y.Yue),fax:+8653189631518.
E-mail address:hewen1960@https://www.doczj.com/doc/1a15573019.html, (W.He).
mesoporous TiO2by using Baker’s yeast cells as templates and its photocatalytic application for treating paper industry wastewater have not been reported.
It is well-known that TiO2can not absorb and utilize visible light due to a wide band gap(3.2eV),which results in low photo-catalytic activity in practical applications.Therefore,currently,the development of new materials for modifying TiO2is urgently needed to improve its light-harvesting and photocatalytic ef?-ciency,especially within the visible-light range[20].Many studies demonstrate that the modi?cation of TiO2both to extend its spec-tral response to the visible region and to improve its catalytic ef?-ciency can be achieved by controlling structure and doping elements like C,N and Ag.Examples hereof are hierarchical nano-structured TiO2and C-,N-and Ag-doped titania nanomaterials that exhibit better photocatalytic activity and extend its spectral re-sponse to visible region[15,21,12].
In this work,a novel method by combination of low-cost Baker’s yeast cell biotemplates with biomimetic mineralization is utilized to prepare Baker’s yeast cell biotemplated TiO2,hereafter referred to as yeast-TiO2.During the biomimetic mineralization process, yeast–TiO2replicated the ordered hierarchical structures of Baker’s yeast cells.In addition,carbon was self-doped into yeast–TiO2from the Baker’s yeast cells during synthesis.The morphology,structure, and chemical composition of yeast–TiO2were characterized,and the mechanism of their formation was discussed.Moreover,the as-prepared yeast–TiO2is?rst employed as the photocatalyst for treating paper industry wastewater(PIW).This highly regulated and hierarchical mesoporous TiO2exhibited excellent photocata-lytic activity and rapid mass transport ability.The present work realizes the synergy of both structure-and element-introduced improvements of the photocatalytic activity of TiO2based on Ba-ker’s yeast cell biotemplate.Yeast–TiO2is considered to be prom-ising for applications in biosensor,solar cells,and photoelectrical devices.Moreover,we expect that the reported approach can be extended to prepare other advanced mesoporous materials in mild condition.
2.Experimental section
2.1.Synthesis of yeast–TiO2
The yeast cells were cultivated in a30mL of glucose aqueous solution(2–5wt%)at room temperature.After30min of stirring, a uniform bioemulsion was formed.The critical micelle concentra-tion(CMC)of the bioemulsion is0.007g mLà1.A solution of10mL of TiCl4(=99.0%)dissolved in20mL of HCl(36–38wt.%)was drop-wise added to the bioemulsion under stirring.The stirring was maintained for24h.Ammonia solution(25–28%)was then added dropwise to adjust the pH to9–10.The formed white precipitate was collected and carefully washed with distilled water and abso-lute ethanol,and dried at80°C in air for about24h.The dried sam-ples were heat-treated at400°C in air for3h to obtain the?nal products.All reagents were of analytical reagent grade.
2.2.Structure characterization
Atomic force microscopy(IIIa AFM)was used to observe the morphologies of the synthesized materials.The samples for AFM measurements were prepared by adding the ethanol suspension with the dispersed particles dropwise onto a freshly cleaved mica piece.Subsequently,the samples were air-dried.
X-ray photoelectron spectroscopy(XPS)measurements were performed on a Kratos Axis Ultra DLD(delay line detector)spec-trometer equipped with a monochromatic Al K a X-ray source (1486.6eV).All binding energies were referenced to the C1s peak at284.8eV of the surface adventitious carbon.
High-resolution transmission electron microscopy(HRTEM) was carried out on a Philips Tecnai20U-TWIN microscope,working at300kV.A trace amount of sample was dispersed in ethanol solu-tion by sonication,and then deposited on a carbon-coated copper grid,which was used as a TEM specimen.
The N2adsorption–desorption isotherms(NADI)were carried out at77K using a computer controlled sorption analyzer (Micromeritics,Gemini V2.0)operating in the continuous mode. The samples were degassed at200°C for10h prior to the measure-ment.The pore-size distribution was calculated from desorption branch of the isotherm by the Barret–Joyner–Halenda(BJH)model.
2.3.Photocatalytic measurement
The photocatalytic activity of the catalysts was evaluated by the degradation of paper industry wastewater(PIW)under visible-light irradiation.Industry wastewater was obtained by diluting 4mL original PIW in100mL measuring?ask.The reaction solution of0.2g of photocatalyst suspended in the above100mL industry wastewater(pH=12.4)was sonicated in dark for15min to obtain a homogeneous suspension and to ensure the establishment of an adsorption/desorption equilibrium.After sonication10mL H2O2 was added to the uniform reaction solution.Then the reaction solution was stirred continuously and irradiated using a light source with400nm wavelength for5h.A circulating water jacket made of quartz was used to control the temperature of lamp and the reaction tubes.The inner diameter of the reaction tube was 6.56cm and the distance between the light source and the reaction tubes was8cm.All reactions were carried out at room tempera-ture.Chemical oxygen demand(COD)concentrations were mea-sured according to standard methods[22]and expressed as CODcr(potassium dichromate as oxidant).The absorbance of the reaction solution was measured using a SP-721spectrophotome-ter.The color removal ef?ciency could be calculated from the relation D(%)=100(A0àA t)/A0,where D is the color removal ef?-ciency,A0the initial absorbance of reaction solution and A t the absorbance of reaction solution at time t,respectively.
3.Results and discussion
3.1.Biomimetic synthesis of yeast–TiO2
Fig.1a illustrates a biomimetic mineralization approach that has been applied to prepare the TiO2.The Baker’s yeast cells used as templates in the TiO2preparation exhibit an oval shape (Fig.1b).The yeast cell wall consists of phosphomannan,mannan, glucan,dextran and proteins for biocatalysis[23].Like most natu-ral cells,S.cerevisiae cannot induce spontaneous mineralization on its surface,due to the relatively low charge density[12].During the cultivation processes of yeast cells(fermentation),a bioemulsi?er with acidic matrix macromolecules metabolites including extracel-lular proteins and polysaccharides[24–26]was produced on the surface of cells.The critical micelle concentration(CMC)of the bio-emulsion is found to be0.007g mLà1.These biosurfaceactive mac-romolecules contain some hydrophilic anion groups including carboxyl andàOPO2à
3
[8,27].It should be mentioned that the hydrophilic anion groups mainly serve for the following two pur-poses:(1)they provide oriented nucleation sites for target cations [28],and(2)they accumulate more negative charges on the bio-template surface.More recently,our previous study con?rmed that the yeast cell surface has surplus negative charges as a result of cultivation[29].
The mineralization ability of yeast cells can be improved by pro-ducing biosurfaceactive macromolecules with hydrophilic anion groups on the cell surface.The biosurfaceactive macromolecules
110W.He et al./Journal of Colloid and Interface Science354(2011)109–115
are intimately involved in regulating crystal nucleation and growth [27,28].When titanium cations were added into the bioemulsion,positively charged titanium cations were combined with the nega-tively charged –COO àand àOPO 2à
3
groups,and were self-assem-bled to the yeast cells surface by electrostatic interaction.This self-assembly induced the formation of a titania layer on the sur-face of the yeast cell wall.Evidence for Ti 4+adsorption was ob-tained by using polarized optical microscopy (POM).Fig.1c displays the POM image of yeast cells after addition of the Ti 4+ions into the bioemulsion mineralizing for 2h.A ring of light,i.e.,a so-called Bake line,is seen on the surface of yeast cell.The Bake line appeared because the refractive index of the Ti 4+shell is higher than that of yeast cells.This indicates that Ti 4+can be rapidly in-duced mineralization on cell wall by recognition and self-assembly processes [28].Next,when ammonia hydroxide solution was added to the system,the yeast/Ti(OH)4core–shell spheres were formed due to in situ hydrolysis and polycondensation of titanium cations.Finally,after calcination,the yeast/Ti(OH)4core–shell spheres converted to yeast–TiO 2.The yeast–TiO 2displays a typical hollow-structured mineral sphere which retains a yeast cell tem-plated pro?le (Fig.1d).The surface of the sphere is covered by
numerous TiO 2nanoparticles with a size of about 10nm in diam-eter.TiO 2nanoparticles are loosely packed to form the porous sur-face.Fig.1e shows a magni?ed TEM image of the partial area in Fig.1d,which shows the hollow structure in the synthesized sam-ples.In summary,the entire process can be brie?y de?ned to four steps:1.Adsorption;2.Inducing mineralization;3.In situ hydroly-sis and polycondensation;4.Removing template.3.2.Morphology and structure of yeast–TiO 2
Fig.2shows the atomic force microscope (AFM)images of the Baker’s yeast cells and the synthesized yeast–TiO 2.In Fig.2a,Ba-ker’s yeast cells exhibit well-de?ned oval shape.Periodic spiculate clusters,wormhole-like textural pores and ‘‘skeletal”mesh-like structures,which present spatial organization and size hierarchy,appear on the surface of yeast cell wall.The yeast–TiO 2possesses well-de?ned cell shape (Fig.2b),and an ampli?ed image displays a highly ordered hierarchical porous surface morphology (Fig.2c).This is consistent with the small angle X-ray diffraction (SAXRD)result (see Fig.S2in the Supporting information ).These characterization results indicate that the mesoporous TiO 2materi-
Hydrophilic groups on the surface of yeast cell
Ti 4+
Adding into Ti 4+ solution
Electrostatic attraction Induced biomineralization
Ti 4+ deposition on yeast cell wall Protein Phosphomannan
Mannan
Glucan
25 ~ 70 nm
Bake lines
Yeast-TiO 2
(a)
(b)(d)
(c)
(e)
1250×1250 nm 260×260 nm 30×38 nm
(a)
(b)
(c)
W.He et al./Journal of Colloid and Interface Science 354(2011)109–115111
als with highly ordered hierarchical structures are readily achiev-able by precisely replicating surface structures of yeast cells.
The AFM results further suggest that the yeast cells play a key role in the creation of the special morphology and structure.As structure directing agents,microbial yeast cells differ from the other templates such as soft or hard chemical templates due to their special biological functions.Living yeast cells are integration of soft templates(biosurfaceactive macromolecules from microbial biocatalysis)and hard templates(cell bodies),which are produced during the cultivation processes.The structure directing effect of the cell bodies as hard templates enables the formation of a hol-low-structured sphere like cell templated pro?le.As described pre-viously,biosurfaceactive macromolecules induce the oriented nucleation of inorganic crystals by recognition processes at the inorganic–organic interface.The induced nucleation and oriented crystal growth of the biosurfaceactive macromolecules as soft tem-plates enables the formation of an ordered hierarchical porous sur-face morphology,during which TiO2nanoparticles are regularly packed.
To investigate the surface element composition of yeast-TiO2, X-ray photoelectron spectroscopy(XPS)was conducted.As shown in Fig.3a,there are Ti,C,O elements in the XPS spectrum.Fig.3b–d shows the high-resolution XPS spectra of C1s,O1s,and Ti2p region, respectively.It is found that the C1s XPS spectrum is composed of three peaks at284.6,286.4,and288.5eV(Fig.3b).They could be assigned to elemental carbon that was originated from the adhe-sive tape used in the XPS test,C?–C@O and O–C?@O bonds[19,30].
Where the respective carbon species were marked by asterisk, respectively.These data reveal substitution of carbon for titanium in the titania lattice,which creates Ti–O–C bonds.High-resolution XPS spectrum of O1s displays three peaks.The peak at531.2eV is relative to the adsorbed hydrated oxygen on the surface of yeast–TiO2,the peak at529.8eV corresponds to the lattice oxygen of TiO2 crystal,and the peak located at528.3eV may be assigned to Ti–O–C@O?bond,where the respective oxygen specie was marked by asterisk(Fig.3c).The presence of the peak from adsorbed hydrated oxygen(–OH,531.2eV)indicates a relatively low electron density around the Ti element on the surface of yeast–TiO2,and this en-hances the oxygen adsorption ability.In the high-resolution XPS spectrum of Ti2p(Fig.3d),the binding energies of Ti2p3/2and 2p1/2were centered at458.6and465.2eV,respectively,revealing that the titanium elements are in the oxidation state IV.The XPS tests demonstrated that C was self-doped into yeast-TiO2from yeast cells.This is consistent with the energy dispersive X-ray anal-ysis(EDX)and X-ray diffraction(XRD)results(see Figs.S1–S2in the Supporting information).EDX and XRD measurements show that yeast–TiO2consists of87.4wt.%anatase and11.4wt.%amor-phous carbon.The carbon could be inherited from the yeast cells.
Fig.4shows the HRTEM images of yeast–TiO2.The anatase lat-tice fringes of the yeast–TiO2are easily seen,indicating its crystal-line nature.The presence of the anatase phase is also con?rmed by the electron diffraction(ED)pattern(Fig.4a,inset).In contrast,the regions without the lattice fringes are amorphous phase C.Thus, these images display three kinds of nanostructures including C core/TiO2shell nanostructures(Fig.4a),the hierarchical worm-like mesoporous structures(Fig.4b),and a string of carbon nanobeads (Fig.4c)in the nanocomposite particles.The HRTEM images indi-cate that amorphous carbon nanoparticles of approximately at 8nm are formed and evenly in situ compound with the nano crystalline grains of anatase to form the nanocomposites.From
112W.He et al./Journal of Colloid and Interface Science354(2011)109–115
the images,the size of the nanocomposite particles is10–12nm, which is consistent with the size of10nm determined from the WAXRD(see Fig.S2in the Supporting information).As seen from Fig.4,carbon and anatase are believed to interact in a C tetrahe-dron core/TiO6octahedron shell nanostructure.Scheme of C tetra-hedron core/TiO6octahedron shell nanostructure is illustrated in Fig.4A(inset).Fig.4d shows schematic drawing of the in situ com-posite structure of the biotemplate TiO2/C nanocomposites.
To obtain further information on the mesoporous structure of the yeast–TiO2,nitrogen adsorption measurements were per-formed(Fig.5).N2-sorption isotherm of yeast–TiO2is of type IV according to the IUPAC classi?cation showing a one-step capillary condensation and a two-step desorption(Fig.5a).The?rst-step desorption is assigned to the desorption of N2from plugged mes-opores whereas the second desorption step can be attributed to the desorption of N2from open mesopores[31].The two types of mesopores can also be seen from HRTEM(Fig.5a,inset),where both the plugged mesopores and the open mesopores are marked by red and green arrows,respectively.Hence,it is shown that a corresponding wide and bimodal pore-size distribution centered on4.7and11.0nm(Fig.5b).The pore volume ratio between the two structures is7:1,indicating that the open-type structure dom-inates the pore volume.This hierarchical mesoporous structure and bimodal pore distribution may in?uence the adsorption and diffusion of molecules within the mesoporous channels of the yeast–TiO2.Therefore,the yeast–TiO2from Baker’s yeast cell bio-templates may be a promising candidate for processes involving catalysts,encapsulation media,controlled release,adsorption,etc.
The characterizations of yeast–TiO2derived from Baker’s yeast cells demonstrate that anatase TiO2/C nanocomposite with ordered open hierarchical mesopores was created.In our work,both biomi-metic nanostructure and in situ element-composited were realized by a simple single-step procedure.In comparison with commonly applied chemical methods to generate mesoporous TiO2,the advantages of our novel approach primarily include:(i)the tem-plates are low-cost and non-toxic,(ii)ordered hierarchical meso-porous structures are easily controlled.In comparison to other biotemplates,the yeast cells are much cheaper and more easily scaled up for industrial applications.
3.3.Photodegradation for paper industry wastewater(PIW)
As analyse described before,element C is self-doped into yeast–TiO2.Doping carbon is one way to improve the light-harvesting properties of TiO2[32].Moreover,the O1s XPS spectrum indicates that yeast–TiO2possess of an O adsorption property.The adsorbed oxygen allows the H+hydroxylation to form–Ti(OH)–O–Ti–(OH)–, since they not only transform the photogenerated hole h+into?OH free radicals,but also prevents electron–hole recombination,and hence,bene?ts photocatalysis[33].
In this work,using the yeast–TiO2as photocatalyst,photodegra-dation of PIW is characterized by irradiating the samples using vis-ible light.It is found that the yeast–TiO2exhibits outstanding photocatalytic performances under visible-light irradiation (Fig.6).The raw PIW has a pH of12.4and a total COD of 581.9?103mg Là1.Under the same conditions,the photodegrada-
(a)
(A)
(c)
(b)
(d)
C
Ti
O anatase anatase
W.He et al./Journal of Colloid and Interface Science354(2011)109–115113
tion effect of yeast–TiO2is superior to that of commercial photocatalyst P25titania(non-porous nanomaterials)on the PIW,especially at radiation durations below2h(Fig.6a).In fact with the yeast–TiO2as photocatalyst,COD removal ef?ciency reached80.3%within5h(Fig.6a),leaving less than1/5of the ori-ginal value,i.e.,the water quality has been signi?cantly improved. Further,Fig.6b shows the color removal as a function of irradiation time.The most dramatic color removal occurs within the?rst hour
5 nm
O O
O O
h+
h+
h+
h+
h+ Black organic matter adsorbed in mesopores Yeast-TiO2
114W.He et al./Journal of Colloid and Interface Science354(2011)109–115
where the color removal reaches nearly100%.The inset illustrates the color change of the PIW before and after photodegradation using the yeast–TiO2as photocatalyst.The photocatalytic results clearly indicate that the yeast–TiO2possess higher visible-light harvesting and photocatalytic abilities.The carbon doping and or-dered hierarchical mesoporous structure play important roles.
The mechanisms occurring on yeast–TiO2surfaces exposed to light for the photodegradation of PIW are summarized in Fig.6c–d and also presented below stepwise.The yeast–TiO2,in which car-bon substitutes for some of the lattice titanium atoms and form a Ti–O–C structure,absorbs light at428nm and558nm and has a lower energy band-gap than that of normal anatase(2.9and2.2 versus3.2eV,see Fig.S3in the Supporting information).The band gaps of2.9and2.2eV correspond to yeast–TiO2and in situ carbon, respectively(Fig.6c).Absorption of visible light(400nm)by TiO2is followed by electron(eà)–hole(h+)pair generation(Step1).The photogenerated electrons then react with hydrogen peroxide (H2O2)to produce hydroxyl(?OH)radicals(Step2).The photogen-erated holes react with surface OHàgroups to form hydroxyl(?OH) radicals(Step3)[34].In alkaline solution,oxygen in the system can ef?ciently trap electrons to produce peroxide(?OOH)radicals(Step 4).As strong oxidants,the holes,?OH,and?OOH can all serve impor-tant roles in the photocatalytic reaction mechanisms.Furthermore, the electrochemical experiments(see Fig.S4in the Supporting information)showed that both mass transfer and charge transfer are rapid for the yeast–TiO2.Hence,the reactive radicals can en-sure rapid decomposition of the organic compounds in PIW(Step 5).Adsorption and photodegradation of organic matter in the mes-opores of yeast–TiO2are illustrated in Fig.6d.
Charge-carrier generation:
TiO2ee—hTth v!TiO2eeàthtT;e1T
Strong oxidants generation:
H2O2teà!?OHtOHà;e2ThttOHàesurfaceT!?OH;e3TO2tH2Oteà!?OOHtOHà;e4T
PIW decomposition:
?OHeand=or htand?OOHTtPIW!Intermediates
!CO2tH2O:e5T
4.Conclusions
A mesoporous anatase TiO2has been successfully synthesized using Baker’s yeast cells as biotemplates.The yeast cells act both as hard templates(cell bodies)directing the formation of a hol-low-structured spheres and as soft templates(bioactive surface macromolecules from microbial catalysis)causing TiO2nanoparti-cles to constitute an ordered hierarchical mesoporous structure. Results of industrial wastewater treatment clearly indicate that the synthesized TiO2is a highly ef?cient visible-light driven photo-catalyst.The high photo-catalytically ef?ciency arises from the fast mass transport,strong visible light absorption,fast decomposition of H2O2and adsorption of organic matter in the mesopores.The proposed approach actually opens a general,ef?cient way to pre-pare advanced mesoporous materials under ambient conditions.Acknowledgments
We thank Lingmei Kong,Xiangjie Guan,Zhengmao Li,Miao Xu and Xu Yang for their technological support,and Robert C.Capen, Carole A.Capen and M.Jensen for useful discussions.The research was supported by Natural Science Foundations of China(Grant Nos.:50872076/E020803,M2008-06and50830101)and Shan-dong Natural Science Foundation of China(Y2008F39and Y2008F08).
Appendix A.Supplementary material
Supplementary data associated with this article can be found,in the online version,at doi:10.1016/j.jcis.2010.10.035.
References
[1]R.R.Naik,M.O.Stone,Mater.Today8(2005)18–26.
[2]S.S.Shankar,A.Rai,B.Ankamwar,A.Singh,A.Ahmad,M.Sastry,Nat.Mater.3
(2004)482–488.
[3]D.Kisailus,J.H.Choi,J.C.Weaver,W.Yang,D.E.Morse,Adv.Mater.17(2005)
314–318.
[4]A.L.Cholli,M.Thiyagarajan,J.Kumar,V.S.Parmar,Pure Appl.Chem.77(2005)
339–344.
[5]M.Jensen,R.Keding,T.H?che,Y.Z.Yue,J.Am.Chem.Soc.131(2009)2717–
2721.
[6]C.S.Chan,G.D.Stasio,S.A.Welch,M.Girasole,B.H.Frazer,M.V.Nesterova,S.
Fakra,J.F.Ban?eld,Science303(2004)1656–1658.
[7]R.R.Naik,S.J.Stringer,G.Agarwal,S.E.Jones,M.O.Stone,Nat.Mater.1(2002)
169–172.
[8]E.Nevoigt,Mol.Biol.Rev.72(2008)379–412.
[9]D.Botstein,G.R.Fink,Science240(1988)1439–1443.
[10]C.T.Dameron,R.N.Reese,R.K.Mehra,A.R.Kortan,P.J.Carroll,M.L.Steigerwald,
L.E.Brus,D.R.Winge,Nature338(1989)596–597.
[11]S.P.Yan,W.He,C.Y.Sun,X.D.Zhang,H.S.Zhao,Z.M.Li,W.J.Zhou,X.Y.Tian,
X.N.Sun,X.X.Han,Dyes Pigm.80(2009)254–258.
[12]Y.M.Wang,G.J.Du,H.Liu,D.Liu,S.B.Qin,N.Wang,C.G.Hu,X.T.Tao,J.Jiao,
Adv.Funct.Mater.18(2008)1131–1137.
[13]E.Wahlstr?m, E.K.Vestergaard,R.Schaub, A.R?nnau,M.Vestergaard, E.
L?gsgaard,I.Stensgaard,F.Besenbacher,Science303(2004)511–513. [14]Y.Y.Song,F.Schmidt-Stein,S.Bauer,P.Schmuki,J.Am.Chem.Soc.131(2009)
4230–4232.
[15]Y.Li,T.Sasaki,Y.Shimizu,N.Koshizaki,J.Am.Chem.Soc.130(2008)14755–
14762.
[16]J.L.Sumerel,W.J.Yang,D.Kisailus,J.C.Weaver,J.H.Choi,D.E.Morse,Chem.
Mater.15(2003)4804–4809.
[17]J.H.Li,X.Y.Shi,L.J.Wang,F.Liu,J.Colloid Interface Sci.315(2007)230–236.
[18]H.L.Su,Q.Dong,J.Han,D.Zhang,Q.X.Guo,Biomacromolecules9(2008)499–
504.
[19]Y.J.Jiang,D.Yang,L.Zhang,Q.Y.Sun,X.H.Sun,J.Li,Z.Y.Jiang,Adv.Funct.
Mater.19(2009)150–156.
[20]X.F.Li,T.X.Fan,H.Zhou,S.K.Chow,W.Zhang,D.Zhang,Q.X.Guo,H.Ogawa,
Adv.Funct.Mater.19(2009)45–56.
[21]X.B.Chen,C.Burda,J.Am.Chem.Soc.130(2008)5018–5019.
[22]B.C.Wu,L.Fei,Modern Environmental Monitoring Technology,China
Environmental Science Press,Beijing,1999,pp.36–42.
[23]E.Cabib,D.H.Roh,M.Schmidt,L.B.Crotti,A.Varma,J.Biol.Chem.276(2001)
19679–19682.
[24]J.A.T.Barriga,D.G.Cooper,E.S.Idziak,D.R.Cameron,Enzyme Microb.Technol.
25(1999)96–102.
[25]G.Georgiou,S.C.Lin,S.M.M.Harma,Bio/Technology10(1992)60–65.
[26]L.Addadi,J.Moradian,E.Shay,N.G.Maroudas,https://www.doczj.com/doc/1a15573019.html,A84
(1987)2732–2736.
[27]L.Addadi,https://www.doczj.com/doc/1a15573019.html,A82(1985)4110–4114.
[28]S.Mann, D.D.Archibald,J.M.Didymus,T.Douglas, B.R.Heywood, F.C.
Meldrum,N.J.Reeves,Science261(1993)1286–1292.
[29]W.He,W.J.Zhou,Y.J.Wang,X.D.Zhang,H.S.Zhao,Z.M.Li,S.P.Yan,Mater.Sci.
Eng.,C29(2009)1348–1350.
[30]Y.Wu,H.Chen,J.H.Cao,C.Z.Fan,Chin.J.Appl.Chem.24(2007)570–574.
[31]P.Van Der Voort,P.I.Ravikovitch,K.P.De Jong,M.Benjelloun,E.Van Bavel,A.H.
Janssen,A.V.Neimark,B.M.Weckhuysen,E.F.Vansant,Phys.Chem.B106 (2002)5873–5877.
[32]S.U.M.Khan,M.Al-Shahry,W.B.I.Jr.,Science297(2002)2243–2245.
[33]M.R.Hoffmann,S.T.Martin,W.Choi,D.W.Bahneman,Chem.Rev.95(1995)
69–96.
[34]K.M.Parida,N.Sahu,N.R.Biswal,B.Naik,A.C.Pradhan,J.Colloid Interface Sci.
318(2008)231–237.
W.He et al./Journal of Colloid and Interface Science354(2011)109–115115