Enhancement of photocatalytic efficiency using heterostructured SiO2-Ta2O5 thin films

Abstract

Fabricationofcontrolledlayeredstructuredthinfilmswithtunablephysicalpropertiesisanimportant areaofresearchasthinfilmtechnologyholdspotentialforavarietyofindustrialapplications.Inthe presentwork,wehavedemonstratedtheprocessforfabricationofmultilayerfilmsofsilicaand tantalumoxidebyLangmuir–Blodgettfilmfabricationtechniqueandinvestigatedtheirphotocatalytic degradationefficiencyfororganicdye(RhodamineB)underUVradiation.Thephotocatalytic degradationofRhBinpresenceofSiO2–Ta2O5exhibitedremarkablyenhancedphotocatalyticactivity thanpureTa2O5.Thisisbecauseofthehighseparationefficiencyofphoto-generatedelectron–hole pair duetotheLewisacidityofsilicaandthegreatercontactareabetweenthesetwolayers.TheSiO2Ta2O5systemwasoptimizedforthenumberofself-assembledlayersofsilicaandtantalumoxide,and it hasbeenfoundthat10S–15T–10S–15T–10S–15T(whereSandTrepresentsSiO2andTa2O5 respectively) pattern hasbeenfoundtohavemaximumphotocatalyticdegradationefficiencyof71% (with18%degradationperunitareaofthefilm)whichis3.5foldhigherthanpureTa2O5under identical experimental condition.Also,thephotocatalyticactivityofthesefilmswasalsoprovedtobe sensitive to thesequenceofsilicaandtantalumoxidelayerswhenthefilmareaofallthesampleswas keptconstant(3.75 cm2).Furtheranalysisconfirmsthatthedegradationofdyemoleculeshasbeen largely promotedbythephotogeneratedholes,ratherthanthesuperoxideradicalanions.