orderwww.13ddd.com

NANOEXPRESSOpenAccessFabricationandphotocatalyticpropertiesofsiliconnanowiresbymetal-assistedchemicaletching:effectofH2O2concentrationYousongLiu1,GuangbinJi1*,JunyiWang1,XuanqiLiang1,ZewenZuo2andYiShi3AbstractInthecurrentstudy,monocrystallinesiliconnanowirearrays(SiNWs)werepreparedthroughametal-assistedchemicaletchingmethodofsiliconwafersinanetchingsolutioncomposedofHFandH2O2.
PhotoelectricpropertiesofthemonocrystallineSiNWsareimprovedgreatlywiththeformationofthenanostructureonthesiliconwafers.
Bycontrollingthehydrogenperoxideconcentrationintheetchingsolution,SiNWswithdifferentmorphologiesandsurfacecharacteristicsareobtained.
Areasonablemechanismoftheetchingprocesswasproposed.
PhotocatalyticexperimentshowsthatSiNWspreparedby20%H2O2etchingsolutionexhibitthebestactivityinthedecompositionofthetargetorganicpollutant,RhodamineB(RhB),underXearclampirradiationforitsappropriateSinanowiredensitywiththeeffectofSicontentandcontactareaofphotocatalystandRhBoptimized.
Keywords:Siliconnanowirearrays,H2O2,PhotocatalyticpropertiesBackgroundPhotocatalysishasattractedmuchinterestduetoitspotentialadvantagesinutilizingsolarenergytodegradeorganicpollutantsanddevelopnewenergy[1-4].
Asatraditionalphotocatalyst,semiconductorTiO2hasenor-mouspotentialinphotocatalysis,butitswidebandgap(3.
2eV)limitstheuseoflightenergy[5,6].
Siliconmaterials,whichexhibitawideopticaladsorp-tionrange,highopticalabsorptionefficiency,andhighelectronmobility,becomeagreatpotentialphotoelectricconversionmaterialforitsimportantapplicationsinthefieldofphotovoltaicsandphotocatalysis[7-10].
Therealizationofthesiliconstructure,especiallytheprepar-ationofnanowirearrays,isverysignificantforthedevel-opmentandproductionofefficientquantumdevices,photoelectricdevices,andelectronicandopticalsensors[11-15].
Variousmethodshavebeendevelopedtopre-pareone-dimensionalsiliconnanostructures,suchaschemicalvapordeposition[16],supercriticalfluid-liquid–solidsynthesis[17],laserablation[18],thermalevaporationdecomposition[19],andotherprocesses.
Inrecentyears,asimplecatalyticetchingtechniquewithmetalparticlesascatalysttopreparelarge-areaalignedmonocrystallinesiliconnanowirearraysonsiliconwafershasbeenreported[20-27].
Thetechniqueisactuallyawetchemicalcorrosion,theprocessofwhichisrelativelysim-ple,lowcost,andcontrollable.
Recentworksontheetch-ingmethodwithdepositionsoftwo-dimensional(2-D)micro/nanoparticlearrays[28-33]or2-Dnanopatternfab-rications[34,35]withhighlyorderedconfigurations,whichareapplicableforenablinghighlydensenanowireforma-tion,havealsobeenreported.
Thecontrolleddepositionsofmicro/nanoparticlesresultinclose-packedhighlyordered2-Darrayswithmonolayerconfiguration,andthesemethodshadbeenimplementedinphotonicdevices[28-33].
Inaddition,theuseofdiblockcopolymerlithog-raphymethodshadenabledthefabricationofhighlyorderedandultrahigh-density2-Dnanopatternarrays[34,35].
However,literaturesabouttheinfluenceofetchingsolutioncompositiononthemorphologiesandpropertiesofSinanowirearraysarerarelyreported.
Inthispaper,weusemonocrystallinesiliconwafersasthematrix,Agasthecatalyst,andhydrofluoricacid(HF)andhydrogenperoxide(H2O2)astheetchingsolu-tiontopreparesiliconnanowirearraysutilizingthewetchemicaletchingmethod.
Thephotoelectricproperties*Correspondence:gbji@nuaa.
edu.
cn1CollegeofMaterialsScienceandTechnology,NanjingUniversityofAeronauticsandAstronautics,Nanjing211100,People'sRepublicofChinaFulllistofauthorinformationisavailableattheendofthearticle2012Liuetal.
;licenseeSpringer.
ThisisanOpenAccessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
Liuetal.
NanoscaleResearchLetters2012,7:663http://www.
nanoscalereslett.
com/content/7/1/663ofthemonocrystallinesiliconnanowirearraysandthesiliconwaferswerealsoinvestigated.
Additionally,inourstudy,wefoundthattheincreaseofH2O2concentrationcaninfluencethemorphologyandsurfacecharacteristicsofthenanowires,whichmayaffecttheirlightabsorptionandphotocatalyticproperties.
MethodsSynthesisofSiNWsInourexperiment,(100)-orientedp-typesiliconwaferswerepurchasedandcutinto2*2cm2smallpiecesusingaglasssword.
Ametalcatalyticetchingmethodwasutilizedtopreparemonocrystallinesiliconnanowirearrays(SiNWs).
Inatypicalprocess,thepiecesoftheselectedsiliconwaferswerewashedbysonicationinacetoneanddeionizedwater.
Then,thesiliconwafersweredippedintoHF/H2Osolution(1:10)toremovethethinoxidationlayeranddriedbyN2blow.
Subsequently,thesiliconwaferswereimmersedinasolutionof0.
14MHFand0.
01MAgNO3for30s.
AfterauniformlayerofAgnanoparticleswascoated,thewaferswerethenimmersedintheetchantsolutioncomposedofHF,H2O2,andH2O(thevolumeratiosare20:10:70,20:20:60,and20:30:50,sotheH2O2concentrationcanberecordedas10%,20%,and30%,respectively)atroomtemperatureinasealedTeflonvessel.
TheSiwaferswereimmersedinasolutionofconcentratednitricacidsolutiontoremovetheexcessAgnanoparticles,rinsedwithdeionizedwater,andthendriedinvacuumat60°C.
CharacterizationofSiNWsThemorphologiesandmicrostructureoftheas-synthesizedSiNWswerecharacterizedbyscanningelectronicmicros-copy(SEM;HITACHI-S4800,Chiyoda-ku,Japan)andtransmissionelectronmicroscopy(TEM;JEOLJEM-2100,Akishima-shi,Japan).
Ultraviolet–visible(UV–vis)absorp-tionspectraoftheSiNWswereobtainedusingaUV–visspectrometer(ShimadzuUV-3600,Kyoto,Japan).
PhotoelectrochemicalmeasurementsThephotoelectrochemicalmeasurementswerecarriedoutinathree-electrodecellina0.
5MNa2SO4electro-lytesolutionwithSinanowirearrays,Ptelectrode,andsaturatedmercuryelectrodeastheworkingelectrode,counterelectrode,andreferenceelectrode,respectively,usingaCHIelectrochemicalanalyzer(CHI660D,CHInstruments,ChenhuaCo.
,Shanghai,China).
A500-Wxenonlampwithalightintensityof400mW/cm2wasusedasthelightsource.
PhotocatalyticdegradationofaqueousRhBoverSiNWsPhotodegradationexperimentswerecarriedoutina100-mLconicalflaskcontaining50-mLRhodamineB(RhB)solutionwithaninitialconcentrationof1ppmunderstirring.
ThepreparedsiliconsubstratewithSinanowirearrayswasputinaquartzdevice,andthere-actionsystemwasilluminatedunderaxenonlamp(lightintensityof400mW/cm2).
Afterevery1h,4mLofthesuspensionwaswithdrawnthroughouttheexperiment.
ThesampleswereanalyzedusingaUV–visspectropho-tometer(ShimadzuUV-3600)afterremovingthecatalystpowdersbycentrifugation.
ResultsanddiscussionStructure,opticalproperties,andphotoelectricpropertiesofSiNWsSEMandTEMofSiNWspreparedwiththeetchingsolutioncontaining10%H2O2(notedas10%SiNWs)InordertostudythemorphologyandstructureoftheSiNWs,SEMandTEMmeasurementswereperformed.
TheSEMimagesofthe10%SiNWsareshowninFigure1.
Fromtop-viewimages(Figure1a,b),itcanbeobviouslyseenthatSiNWswithsomecongregatedbundleswereobtained.
Basedonthecross-sectionalSEMimage(Figure1c),thenanowiresthatareapproximately13to16μminlengthareverticaltothesubstratesurface.
Figure1disthemagnifiedcross-sectionalimageoftheSiNWswhichshowsthatthediameterisabout130to170nmandthewiresareuniformandstraight.
Allthesemorphologycharacterizationsshowthatthroughtheetch-ingreactiononsiliconwafers,theSinanowirestructurehasbeenrealized.
Comparedwiththesiliconbulkmater-ial,thepreparednanowirearrayslayareliablefoundationinthestructurefortheirimprovementinphotoelectricandphotocatalyticperformance.
Figure2istheTEMimageof10%SiNWswhichclearlyshowsthatthenanowiresaregatheredandhaveabunchshape.
TheSinanowirespossessadiameterofabout130to170nmandalengthofabout3μm,whichismuchshorterthanthatoftheSEMresultsandmayhaveresultedfromthesplittingofthesiliconnanowiresbyultrasonicationinthesamplingpreparationprocess.
Thehigh-magnificationillustrationfurtherprovesthatthenanowires'diameteristhesamewiththatoftheSEMtestresults.
Moreover,itcanbeclearlyseenthattheSinanowiredisplaysaninhomogeneouscolor,indi-catingthatthediameterofSinanowiresprearedviathemetalcatalyticetchingmethodisinhomogeneous.
UV–visabsorptionanddiffusereflectionspectraFigure3comparestheUV–visabsorptionanddiffusereflec-tionfromabaresiliconwaferandasampleof10%SiNWs.
Figure3ashowsthatthe10%SiNWsexhibitanexcellentantireflectionpropertyandthereflectionisbelow3%forawiderangeofwavelengths.
Itmaybeascribedtothelight-trappingeffectcausedbytheconstructionoftheSiNWnanostructure,leadingtotheincidentlightbeingreflectedandrefractedinmultiplenanowirearraysandeventuallyLiuetal.
NanoscaleResearchLetters2012,7:663Page2of9http://www.
nanoscalereslett.
com/content/7/1/663beingeffectivelyabsorbed.
Thesiliconwafershowsmorethan30%reflectionforwavelengths200to800nm,andthereflectioncanbeashighas64%inultravioletareas.
AsshowninFigure3b,theabsorptionspectrawereconvertedfromthereflectionspectrabythestandardKubelka-Munkmethod,fromwhichitcanbeseenthattheadsorptionin-tensityofthe10%SiNWsisobviouslystrongerthanthatofthebareSiwaferacrosstheentireUVandvisiblelight.
TheresultsdemonstratethattheopticalpropertiesandthelightabsorptionperformancehavebeenimprovedgreatlyduetotheconstructionoftheSinanowirestructure.
PhotoelectrochemicalresultsFigure4showsthephotoelectrochemicalresultsofthesili-conwaferand10%SiNWs.
Fromthephotoelectrochemicalresultsofthesiliconwaferand10%SiNWs,wecanobvi-ouslydrawtheconclusionthatintheilluminationcondi-tion,thelightcurrentofthe10%SiNWsishigherthanthatofthesiliconwafer(10%SiNWs,0.
35mA;Si,0.
09mA;withanappliedvoltageof0.
5V).
Theimprovedlightcurrentmaybeascribedtotheenhancedadsorptionabilityandphotogeneratedcarrierseparationefficiencyofthe10%SiNWs,takingadvantageoftheformationoftheSinano-wirestructure.
Therefore,itcanbeclearlyinferredthattheconstructionofthenanostructureisaneffectivewaytoim-provethephotoelectricperformanceofsiliconmaterials.
InfluenceofH2O2concentrationonthestructureandphotocatalyticpropertiesofSiNWsAsH2O2isanimportantcomponentintheetchingsolu-tion,ourresultsshowthattheincreaseofH2O2concentra-tioncanaffectthemorphologyandsurfacecharacteristicsFigure2TEMimageof10%SiNWsandthehigh-magnificationimageofaselectedarea(inset).
Figure1SEMimagesofthe10%SiNWs:(a,b)topviewand(c,d)crosssection.
Liuetal.
NanoscaleResearchLetters2012,7:663Page3of9http://www.
nanoscalereslett.
com/content/7/1/663ofthenanowires.
Asdescribedintheabove'Methods'sec-tion,wechangeasingle-variablecondition-theconcentra-tionofH2O2intheetchingprocesstopreparedifferentSiNWsnotedas20%and30%SiNWs.
Characterizationof20%and30%SiNWsFigure5istheSEMimagesoftheSiNWspreparedinanetchingsolutionwithdifferentH2O2concentrations.
ItcanbeobviouslyseenfromFigure5a,bthatasthecon-centrationofH2O2isincreasedfrom10%to20%,the20%SiNWsclearlypresentabetterlinearmorphologywiththenanowirediametersapproximatelyrangingfrom70to180nm.
Moreover,incomparisonwiththe10%SiNWs,whichshowareunionphenomenonandhighnanowiredensity,20%SiNWspossessadiffusionconfigurationandlownanowiredensitywiththenano-wirespaceenlarged.
WhentheconcentrationofH2O2isfurtherincreasedto30%,thepreparedSiNWsdonotshowanexpectedmorphologyofsiliconnanowirearraysbutachaoticporousstructure(Figure5c,d).
WiththeexcessiveconcentrationofH2O2,theprobabilityofhori-zontaletchingincreasesandinfluencestheverticaletch-ingdirection.
Alongwiththeincreaseofthehorizontaletchingspeed,itmayevenovercomeAgparticlegravityandinfluenceofverticaletchingspeedandintensity,lead-ingtoachaoticporousstructureonthesiliconsubstrate.
Themorphologicalfeaturesaboveshowthatanap-propriateimprovementoftheH2O2concentration(20%)canenlargethespaceofthepreparednano-wiresandinfluencetheirdensitywhichmayaffectthelightabsorptionandphotocatalyticproperties.
However,whentheH2O2concentrationistoohigh(30%),achaoticporoussiliconstructure,insteadofnanowirearrays,isformed,causedbythehorizontaletchingspeedovercomingAgparticlegravityandverticaletchingspeedundertheinfluenceofexces-sivelyhighconcentrationofH2O2.
PhotocatalyticactivitiesofSiNWsWithawideopticaladsorptionrangeandhighabsorptionintensity,theSiNWsareexpectedtobepotentialinthephotocatalyticfield.
Aseriesofexperimentsforthephotode-gradationofRhBundertheilluminationofa400-mW/cm2Figure3UV–vis(a)diffusereflectionand(b)absorptionspectraofthesiliconwaferandSiNWs.
Figure4Photoelectrochemicalresultsofsiliconwaferand10%SiNWs.
Liuetal.
NanoscaleResearchLetters2012,7:663Page4of9http://www.
nanoscalereslett.
com/content/7/1/663xenonlampwerecarriedoutinordertoevaluatethephotocatalyticactivityofSiNWs(asshowninFigure6).
AsshowninFigure6a,b,c,thetypicalabsorptionpeakofRhBafterdegradationby10%,20%,and30%SiNWs,respectively,wasdecreasedwiththeextensionoftheir-radiationtime,especiallyinthefirst1hwhichmayhaveresultedfromtheadsorptioneffect.
AsshowninFigure6d,thedegradationrateofRhBreachedtoabout30%,35%,and20%for10%,20%,and30%SiNWs,respectively,after5hofirradiation.
Theresultsclearlydemonstratethatthesiliconnanowirescanfunctionaseffectivephotocatalystswithlightir-radiationandthe20%SiNWsexhibitthehighestphotocatalyticdecompositionefficiency,whilethe30%SiNWswithachaoticporousstructurewastheworst.
Theenhancedcatalyticactivityofthe20%SiNWscouldbeattributedtotheirmorphologycharacterizationwhichpossessesanappropriatenanowiredensitytooptimizetheeffectofSicontentandcontactareaofthephotocatalystandRhB.
FormationmechanismofSiNWarraysInbrief,themetal-assistedchemicaletchingmethodtopreparesiliconnanowiresisaprocessinwhichsiliconisoxidizedintoSiO2usingmetalnanoparticles(suchasAu,Ag,Fe,etc.
)ascatalystsandH2O2asoxidantandthenetchedusingHFsolution.
Metal-assistedchemicaletchingtopreparesiliconnanowirescanbedividedintotwoprocesses(takingAgasanexample):1.
AsshowninFigure7a,whenthesiliconwaferisimmersedintoAgNO3/HFmixturesolution,silverionsinthevicinityofthesiliconsurfacecaptureelectronsfromsiliconanddepositonthesiliconsubstratesurfaceintheformofmetallicsilvernuclei;atthesametime,thesiliconaroundthesilvernucleiisoxidizedtoSiO2.
Theprocessisthesameasthemechanismofthedepositionofcoppernanoparticlesonsiliconsubstratesurface[36],whichisthereplacementreaction,andcanbedividedintotwosynchronousreactionsteps(thecathodereactionandtheanodereaction):a.
Cathodereaction:Ag++e=AgEθ=0.
79Vb.
Anodereaction:Si+2H2O=SiO2+4H++4eEθ=0.
91VSiO2+6HF=SiF62+2H2O+2H+c.
Overallreaction:Si+6HF+4Ag+=4Ag+SiF62+6H+Figure5SEMimagesofSiNWswithdifferentH2O2contents:(a,b)20%and(c,d)30%.
Liuetal.
NanoscaleResearchLetters2012,7:663Page5of9http://www.
nanoscalereslett.
com/content/7/1/663Figure6UV–visabsorptionspectraofRhBsolutionandC-tcurvesofSiNWs.
(a-c)UV–visabsorptionspectraofRhBsolutiondecomposedbySiNWswithdifferentH2O2contentsunderXearclampirradiation:(a)10%,(b)20%,(c)30%.
(d)C-tcurvesofthethreekindsofSiNWs.
Figure7MechanismdiagramofAgdepositionontheSisurfaceinHF/AgNO3solution.
(a)FormationofAgnucleation.
(b)AgparticlegrowthandSisubstrateoxidation.
(c)AgparticlestrappedinthepitsformedbytheetchingofSiO2arounditbyHF.
Liuetal.
NanoscaleResearchLetters2012,7:663Page6of9http://www.
nanoscalereslett.
com/content/7/1/663ThesilvernucleiattachedtotheSisubstratehavehigherelectronicactivitythansiliconatomsandcon-stantlyobtainelectronsfromsiliconatoms,whichmakesthecathodereactiontooccurconstantlyandresultsinthesilvernucleigraduallygrowinguptoformsilvernanoparticles(asshowninFigure7b).
Atthesametime,thesiliconatomaroundthesilvernanoparticlesisoxi-dizedtoSiO2anddissolvedbyHFintheformofSiF62,leadingtotheAgnanoparticlesdownintothewafer(Figure7c).
2.
AsshowninFigure8a,whenthesiliconsubstratedepositedwithsilvernanoparticlesisimmersedinHF-H2O2etchingsolution,SiO2iscontinuouslyformedfromthesiliconcontactedwithsilvernanoparticleswithH2O2asholedonorandoxidantanddissolvedbyHF,leadingtothesinkingofthesilvergrains.
Withthesiliconaroundthesilvernanoparticlesconstantlyoxidizedanddissolved,thesiliconsubstrateisetchedtoformsiliconnanowires(Figure8b):a.
Cathodereaction:H2O2+2H+→2H2O+2h+Eθ=1.
76Vb.
Anodereaction:Si+6HF+nh+→H2SiF6+nH++[n/2]H2c.
Overallreaction:Si+6HF+n/2H2O2→H2SiF6+nH2O+[2n/2]H2Intheprocess,AgNO3playsanimportantroleinformingsilvergrainsasacatalysttopromotetheetchingreaction.
Previousresearch[37]showsthatinmetalaux-iliaryetching,theformationofverticalnanowiresisrela-tivetoetchinglimitationaroundsilvernanoparticles.
Silvernanoparticlesonsiliconsurfacecouldcatalyzetheetchingreactionaroundandbelowthesiliconsubstratetoformpitsandthensinkintothepitsasaresultofgravity,sotheetchingreactionisalongtheverticaldirection.
WiththeincreaseofH2O2concentrationwhichactsasholedonorandoxidantintheetchingprocess,theoxidationspeedofthesiliconaroundtheAgnanoparti-clesincreases,resultingintheincreaseofthehorizontaletchingspeedofthesilicon.
WhentheH2O2concentra-tionreaches20%intheetchingsolution,asshowninFigure8c,moresiliconaroundAgnanoparticleswillbeoxidatedintoSiO2andthendissolvedbyHF,leadingtoanincreasedhorizontaletchingspeed,whichresultsinthe20%SiNWspossessingadiffusionconfigurationandlownanowiredensitywiththenanowiresspaceenlarged(Figure8d).
WhentheconcentrationofH2O2isfurtherincreasedto30%,thehorizontaletchingspeedincreasesinahigherdegreeandovercomestheAgnanoparticlegravitytoshiftitsposition,deviatingfromtheverticaldirection(Figure8e).
Finally,thepreparedSiNWsdonotpresentanexpectedmorphologyofsiliconnanowirearraysbutachaoticporousstructureonthesiliconsub-strate(Figure8f).
ConclusionsSiNWshavebeenpreparedsuccessfullythroughasim-ple,convenient,andcontrollablemetal-assistedchemicaletchingmethod.
Theformationmechanisms,electricalFigure8SchematicdiagramofAgnanoparticle-assistedetchingwiththeincreaseofH2O2concentration:(a,b)10%,(c,d)20%,and(e,f)30%.
Liuetal.
NanoscaleResearchLetters2012,7:663Page7of9http://www.
nanoscalereslett.
com/content/7/1/663properties,andopticalpropertiesaswellasphotocata-lyticperformanceshavealsobeenstudied.
Thephoto-electrochemicalresultsshowthattheformationoftheSinanowirestructuregreatlyimprovedthephotoelectricperformances.
BychangingtheH2O2concentrationintheetchingsolution,weget10%,20%,and30%SiNWswithdifferentmorphologiesofhigh-densitynanowirearrays,low-densitynanowirearrays,andachaoticpor-ousnanostructure,respectively.
Thephotocatalyticre-searchshowsthat20%SiNWsexhibitanenhancedphotocatalyticactivitythan10%and30%SiNWs,whichcouldbeascribedtotheappropriatenanowiredensitywiththeeffectofSicontentandcontactareaofphoto-catalystandRhBoptimized.
CompetinginterestsTheauthorsdeclarethattheyhavenocompetinginterests.
Authors'contributionsYLcarriedoutthepreparationandmaincharacterizationoftheSiNWs,participatedinthesequencealignment,anddraftedthemanuscript.
GJcarriedouttheperformancetestandparticipatedinitsdesignandcoordination.
JWparticipatedinthedataanalysisandEnglishdescriptionmodification.
XLparticipatedintheUV–visspectratestingandanalysis.
ZZparticipatedintheformationmechanismanalysisofSiNWs.
YSparticipatedinthedesignofthestudy.
Allauthorsreadandapprovedthefinalmanuscript.
AcknowledgmentsTheworkisfinanciallysupportedbytheNationalNaturalScienceFoundationofChina(nos.
51172109and61106011),theJiangsuProvinceNaturalScienceFoundation(no.
BK2010497),theFundingofJiangsuInnovationProgramforGraduateEducation(no.
CXLX12_0148),andtheFundamentalResearchFundsfortheCentralUniversities.
Authordetails1CollegeofMaterialsScienceandTechnology,NanjingUniversityofAeronauticsandAstronautics,Nanjing211100,People'sRepublicofChina.
2CollegeofPhysicsandElectronicsInformation,AnhuiNormalUniversity,Wuhu241000,People'sRepublicofChina.
3CollegeofElectronicScienceandEngineering,NanjingUniversity,Nanjing210093,People'sRepublicofChina.
Received:23September2012Accepted:22November2012Published:5December2012References1.
ShaoGS,WangFY,RenTZ,LiuYP,YuanZY:Hierarchicalmesoporousphosphorusandnitrogendopedtitaniamaterials:synthesis,characterizationandvisible-lightphotocatalyticactivity.
ApplCatalB2009,92:61–67.
2.
ShaoGS,LiuL,MaTY,WangFY,RenTZ,YuanZY:Synthesisandcharacterizationofcarbon-modifiedtitaniaphotocatalystswithahierarchicalmeso-/macroporousstructure.
ChemEngJ2010,160:370–377.
3.
PardeshiSK,PatilAB:Solarphotocatalyticdegradationofresorcinolamodelendocrinedisrupterinwaterusingzincoxide.
JHazardMater2009,163:403–407.
4.
PanHB,WangF,HuangJL,ChenNS:BindingcharacteristicsofCoPc/SnO2byin-situprocessandphotocatalyticactivityundervisiblelightirradiation.
ActaPhys-ChimSin2008,24:992–996.
5.
YooKH,KangKS,ChenY,HanKJ,KimJ:TheTiO2nanoparticleeffectontheperformanceofaconductingpolymerSchottkydiode.
Nanotechnology2008,19:505202.
6.
ZhangHJ,ChenGH,BahnemanDW:Photoelectrocatalyticmaterialsforenvironmentalapplications.
JMaterChem2009,19:5089–5121.
7.
KangZH,TsangCHA,WongNB,ZhangZD,LeeST:Siliconquantumdots:ageneralphotocatalystforreduction,decomposition,andselectiveoxidationreactions.
JAmChemSoc2007,129:12090–12091.
8.
KangZH,LiuY,TsangCHA,MaDDD,FanX,WongNB,LeeST:Water-solublesiliconquantumdotswithqavelength-tunablephotoluminescence.
AdvMater2009,21:661–664.
9.
ShaoMW,ChengL,ZhangX,MaDDD,LeeST:ExcellentphotocatalysisofHF-treatedsiliconnanowires.
JAmChemSoc2009,131:17738–17739.
10.
MegoudaN,CofininierY,SzuneritsS,HadjersiT,ElKechaiO,BoukherroubR:PhotocatalyticactivityofsiliconnanowiresunderUVandvisiblelightirradiation.
ChemCommun2011,47:991–993.
11.
ChanCK,PengH,LiuG,McIlwrathK,ZhangXF,HugginsRA,CuiY:High-performancelithiumbatteryanodesusingsiliconnanowires.
NatNanotechnol2008,3:31–35.
12.
KelzenbergMD,BoettcherSW,PetykiewiczJA,Turner-EvansDB,PutnamMC,WarrenEL,SpurgeonJM,BriggsRM,LewisNS,AtwaterHA:EnhancedabsorptionandcarriercollectioninSiwirearraysforphotovoltaicapplications.
NatMater2010,9:239–244.
13.
HochbaumAI,ChenR,DelgadoRD,LiangW,GarnettEC,NajarianM,MajumdarA,YangP:Enhancedthermoelectricperformanceofroughsiliconnanowires.
Nature2008,451:163–167.
14.
HochbaumAI,GargasD,HwangYJ,YangP:Singlecrystallinemesoporoussiliconnanowires.
NanLett2009,9:3550–3554.
15.
FllH,HartzH,Ossei-WusuE,CarstensenJ,RienmenschneiderO:SinanowirearraysasanodesinLiionbatteries.
PhysStatusSolidiRRL2010,4:4–6.
16.
BallJ,ReehalHS:Theinfluenceofsubstrateorientationonthedensityofsiliconnanowiresgrownonmulticrystallineandsinglecrystalsubstratesbyelectroncyclotronresonancechemicalvapourdeposition.
ThinSolidFilms2012,520:2467–2473.
17.
LiuL,ShaoMW,LeeST:Siliconnanowiresforcatalystsandsensors.
JNanoengNanomanuf2012,2:102–111.
18.
MoralesAM,LieberCM:Alaserablationmethodforthesynthesisofcrystallinesemiconductornanowires.
Science1998,279:208–211.
19.
HolmesJD,JohnstonKP,DotyRC,KorgelBA:Controlofthicknessandorientationofsolution-grownsiliconnanowires.
Science2000,287:1471–1473.
20.
KimJ,KimYH,ChoiSH,LeeW:Curvedsiliconnanowireswithribbon-likecrosssectionsbymetal-assistedchemicaletching.
ACSNano2011,5:5242–5248.
21.
QuYQ,LiaoL,LiYJ,ZhangH,HuangY,DuanXF:Electricallyconductiveandopticallyactiveporoussiliconnanowires.
NanoLett2009,9:4539–4543.
22.
QuYQ,ZhouHL,DuanXF:Poroussiliconnanowires.
Nanoscale2011,3:4060–4068.
23.
HuangZ,GeyerN,WernerP,deBoorJ,GseleU:Metal-assistedchemicaletchingofsilicon:areview.
AdvMater2011,23:285–308.
24.
TangJ,ShiJW,ZhouLL,MaZQ:FabricationandopticalpropertiesofsiliconnanowiresarraysbyelectrolessAg-catalyzedetching.
Nano-MicroLett2011,3(2):129–134.
25.
LiX:Metalassistedchemicaletchingforhighaspectrationanostructures:areviewofcharacteristicsandapplicationsinphotovoltaics.
CurrOpininSolidStateMaterSci2012,16:71–81.
26.
ShinJC,ZhangC,LiXL:Sub-100nmSinanowireandnano-sheetarrayformationbyMacEtchusinganon-lithographicInAsnanowiremask.
Nanotechnology2012,23:305305–305310.
27.
ShinJC,ChandaD,ChernW,YuKJ,RogersJA,LiX:Experimentalstudyofdesignparametersinsiliconmicropillararraysolarcellsproducedbysoftlithographyandmetal-assistedchemicaletching.
IEEEJPhotovoltaics2012,2:129–133.
28.
EeYK,ArifRA,TansuN,KumnorkaewP,GilchristJF:EnhancementoflightextractionefficiencyofInGaNquantumwellslightemittingdiodesusingSiO2/polystyrenemicrolensarrays.
ApplPhysLett2007,91:221107.
29.
KumnorkaewP,EeYK,TansuN,GilchristJF:Investigationofthedepositionofmicrospheremonolayersforfabricationofmicrolensarrays.
Langmuir2008,24:12150–12157.
30.
LiXH,SongR,EeYK,KumnorkaewP,GilchristJF,TansuN:LightextractionefficiencyandradiationpatternsofIII-nitridelight-emittingdiodeswithcolloidalmicrolensarrayswithvariousaspectratios.
IEEEPhotonicsJournal2011,3:489–499.
Liuetal.
NanoscaleResearchLetters2012,7:663Page8of9http://www.
nanoscalereslett.
com/content/7/1/66331.
KooWH,YounW,ZhuP,LiXH,TansuN,SoF:Lightextractionoforganiclightemittingdiodesbydefectivehexagonal-close-packedarray.
AdvFunctMater2012,22:3454–3459.
32.
EeYK,BiserJM,CaoWJ,ChanHM,VinciRP,TansuN:MetalorganicvaporphaseepitaxyofIII-nitridelight-emittingdiodesonnanopatternedAGOGsapphiresubstratebyabbreviatedgrowthmode.
IEEEJSelTopQuantumElectron2009,15:1066–1072.
33.
EeYK,KumnorkaewP,ArifRA,TongH,GilchristJF,TansuN:LightextractionefficiencyenhancementofInGaNquantumwellslight-emittingdiodeswithpolydimethylsiloxaneconcavemicrostructures.
OptExpress2009,17:13747–13757.
34.
LiuG,LiuGY,ZhaoHP,ZhangJ,ParkJH,MawstLJ,TansuN:Selectiveareaepitaxyofultra-highdensityInGaNquantumdotsbydiblockcopolymerlithography.
NanoscaleResLett2011,6:342–352.
35.
KuechTF,MawstLJ:NanofabricationofIII–Vsemiconductorsemployingdiblockcopolymerlithography.
JPhysDApplPhys2010,43:183001.
36.
PanZW,DaiZR,XuL,LeeST,WangZL:Temperature-controlledgrowthofsilicon-basednanostructuresbythermalevaporationofSiOpowders.
JPhysChemB2001,105:2507–2514.
37.
YeS,IchiharaT,UosakiK:Spectroscopicstudiesonelectrolessdepositionofcopperonahydrogen-terminatedSi(111)surfaceinfluoridesolutions.
JElectrochemSoc2001,148:C421–426.
doi:10.
1186/1556-276X-7-663Citethisarticleas:Liuetal.
:Fabricationandphotocatalyticpropertiesofsiliconnanowiresbymetal-assistedchemicaletching:effectofH2O2concentration.
NanoscaleResearchLetters20127:663.
Submityourmanuscripttoajournalandbenetfrom:7Convenientonlinesubmission7Rigorouspeerreview7Immediatepublicationonacceptance7Openaccess:articlesfreelyavailableonline7Highvisibilitywithintheeld7RetainingthecopyrighttoyourarticleSubmityournextmanuscriptat7springeropen.
comLiuetal.
NanoscaleResearchLetters2012,7:663Page9of9http://www.
nanoscalereslett.
com/content/7/1/663