title: Spatial charge separation in asymmetric structure of Au nanoparticle on TiO2 nanotube by light-induced surface potential imaging.
abstract: Both enhancing the excitons' lifetime and ingeniously controlling the spatial charge transfer are the key to the realization of efficiently photocatalytic and artificially photosynthetic devices. Nanostructured metal/metal-oxide interfaces often exhibit improved energy conversion efficiency. Understanding the surface potential changes of nano-objects under light illumination is crucial in photoelectrochemical cells. Under ultraviolet (UV) illumination, here, we directly observed the charge separation phenomena at the Au-nanoparticle/TiO2-nanotube interfaces by using Kelvin probe force microscopy. The surface potential maps of TiO2 nanotubes with and without Au nanoparticles were compared on the effect of different substrates. We observed that in a steady state, approximately 0.3 electron per Au particle of about 4 nm in diameter is effectively charged and consequently screens the surface potential of the underlying TiO2 nanotubes. Our observations should help design improved photoelectrochemical devices for energy conversion applications.
authors.affiliation: Department of Energy Science, ‡Integrated Energy Center for Fostering Global Creative Researchers (BK 21 plus), and §School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 440-746, South Korea.
authors.forename: Hyunjun
authors.initials: H
authors.lastname: Yoo
authors.forename: Changdeuck
authors.initials: C
authors.lastname: Bae
authors.forename: Yunjeong
authors.initials: Y
authors.lastname: Yang
authors.forename: Seonhee
authors.initials: S
authors.lastname: Lee
authors.forename: Myungjun
authors.initials: M
authors.lastname: Kim
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Kim
authors.forename: Yunseok
authors.initials: Y
authors.lastname: Kim
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Shin