Graphene oxide embedded into TiO2 nanofiber: Effective hybrid photocatalyst for solar conversion

Abstract

One-dimensional TiO2 nanofibers (NFs) in which graphene oxide (GO) sheets were incorporated (GO-TiO2 NFs) were prepared by using a sol-gel method and an electro-spinning technique. Unlike typical graphene/TiO2 composites that have TiO2 nanoparticles loaded on graphene/GO sheets, GO in GO-TiO2 NF is embedded within the matrix of TiO2 NF that consists of closely packed TiO2 nanoparticles. GO-TiO2 NF was characterized by various analytical methods and tested for its photocatalytic and photoelectrochemical activities. The inclusion of GO sheets in TiO2 NF improved the photocatalytic and photoelectrochemical activities: the photocatalytic hydrogen production and photocurrent generation increased by 1.7 and 8.5 times, respectively. GO sheets embedded in TiO2 NFs can improve the interparticle connection and facilitate the charge pair separation by serving as an in-built electron collector and conduit. Therefore, the enhanced photo(electro)chemical activities in the presence of embedded GOs are related to the retarded charge recombination rate and the lower charge transfer resistance. The advantages of GO-TiO2 NF were confirmed by comparing with a different composite of GO/TiO2 NF having GO sheets bound to the external surface of TiO 2 NF (GO(s)-TiO2 NF). The photocatalytic hydrogen production with GO-TiO2 NF was higher than GO(s)-TiO2 NF both in the absence and presence of Pt cocatalyst, which is mainly ascribed to the stronger electronic coupling between GO sheets and TiO2 matrix and the reduced light shielding by GO buried inside of TiO2 NF. Whether GO sheets are present within the NF matrix or on the external surface of NF critically influences the photocatalytic activity. © 2013 Elsevier Inc. All rights reserved.