title: Photoelectrochemical properties of N/C-codoped TiO2 film electrodes prepared by reactive DC magnetron sputtering.
abstract: This paper aims to characterize the photoelectrochemical properties of the visible-light enabling titanium dioxide (TiO2) film electrodes prepared by codoping nitrogen (N) and a presputtered carbon film (C-film) onto indium tin oxide (ITO) glass substrates using a direct current (DC) magnetron sputtering technique. To improve its photoelectrochemical properties, different amount of C-doping sources, 2 h and 4 h C-film, are chose to prepare the N/C-codoped TiO2 film electrodes. Under visible-light (420 < lambda < 610 nm) illumination, a remarkable photocurrent density of 22 microA/cm2 is obtained for the N/C-TiO2 film electrode prepared with a 4 h C-film (NC(4)-T) at an applied potential of +1.2 V versus SCE. Under ultraviolet (lambda approximately 365 nm) illumination, the NC(4)-T film electrode also exhibits the highest photocurrent density of 0.23 mA/cm2 among all samples tested. A more negative flat band potential of NC(4)-T film electrode is attributed to the synergistic effect of N/C codoping. The XRD spectrum of the NC(4)-T film electrode shows mainly the well-crystallized anatase TiO2 phase and an extremely intense (211) plane. Thus, photoelectrochemical activity of the NC(4)-T film electrode can be ascribed to the well-crystallized columnar crystals with pores at its grain boundary, open surface morphology, which are revealed by SEM and TEM images, and a more negative flat band potential. The visible-light induced activity is mostly enhanced as a result of the synergistic effects of N/C-codoping into the TiO2 crystals. A potential application to photocatalytic splitting of water for hydrogen evolution using solar light is practically possible.
authors.affiliation: Department of Marine Engineering, National Kaohsiung Marine University, Kaohsiung 811, Taiwan.
authors.forename: Kee-Rong
authors.initials: KR
authors.lastname: Wu
authors.forename: Chung-Wei
authors.initials: CW
authors.lastname: Yeh
authors.forename: Chung-Hsuang
authors.initials: CH
authors.lastname: Hung
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Chung
authors.forename: Li-Hsun
authors.initials: LH
authors.lastname: Cheng