TiO2_nanotubes,_nanochannels_and_mesosponge：_Self-organized_formation_and_applications

Pleasecitethisarticleinpressas:D.Kowalski,etal.,NanoToday(2013),http://dx.doi.org/10.1016/j.nantod.2013.04.010ARTICLEINPRESS+ModelNANTOD-315;No.ofPages30NanoToday(2013)xxx,xxx—xxxAvailableonlineatwww.sciencedirect.comjournalhomepage:www.elsevier.com/locate/nanotodayREVIEWTiO2nanotubes,nanochannelsandmesosponge:Self-organizedformationandapplicationsDamianKowalskia,1,DoohunKimb,2,PatrikSchmukia,c,∗aDepartmentofMaterialsScience,UniversityofErlangen-Nurnberg,Martensstrasse7,D-91058Erlangen,GermanybBatteryResearchCenter,KoreaElectrotechnologyResearchInstitute(KERI),Changwon641-120,SouthKoreacDept.ofChemistry,KingAbdullazizUniversity,Jeddah,Saudi-ArabiaReceived23December2012;receivedinrevisedform26April2013;accepted30April2013KEYWORDSTiO2nanotubes;Nanopores;Non-thickness-limitedoxides;Anodization;Self-organizednanostructures;NanofabricationSummaryAnodizationofvalvemetalsandalloysisapowerfultooltocontrolnanoscalearchitectureformanymetaloxides.Exceptforaluminum,themostexploredsystemisself-organizedoxideformedontitanium,namelyself-organizedTiO2nanotubes,becauseoftheuniquecombinationofgeometrywiththesemiconductivenatureoftitaniathatisapplicableinphotocatalysis,lightharvestingsystems,electrochromicdevices,batteries,matrices,tem-plates,filtrationmembranes,andbio-compatiblematerials.Inthiscontribution,wereviewrecentadvancesintheformationofnanostructuredoxidesintheformofnanotubes,nanoporeswithathrough-holemorphology,mesosponges,nanochannelsandmicroconesgrownonTi,Nb,Ta,Zr,Hf,W,Vandtheiralloys.Wediscussmechanismsoftheirformation,keyfunctionalfeatures,anddescribetheirapplicationsinvariousfieldsofchemistryandelectrochemistry.©2013ElsevierLtd.Allrightsreserved.IntroductionAnodizationofsomemetalsandalloys(suchasTi,Nb,Ta,Zr,Hf,W,Al)leadseithertotheformationofcompactoxidelayers,socalledbarrier-typeanodicoxides,orporousoxidesintheformofnanopores,nanotubes(orderedordisorderedlayers),mainlydependingontheelectrolyteused(Fig.1).Theoxidelayersformedaredielectricsorsemiconductors∗Correspondinga