title: Enhanced photoelectrochemical water splitting performance of anodic TiO(2) nanotube arrays by surface passivation.
abstract: One-dimensional anodic titanium oxide nanotube (TONT) arrays provide a direct pathway for charge transport, and thus hold great potential as working electrodes for electrochemical energy conversion and storage devices. However, the prominent surface recombination due to the large amount surface defects hinders the performance improvement. In this work, the surface states of TONTs were passivated by conformal coating of high-quality Al2O3 onto the tubular structures using atomic layer deposition (ALD). The modified TONT films were subsequently employed as anodes for photoelectrochemical (PEC) water splitting. The photocurrent (0.5 V vs Ag/AgCl) recorded under air mass 1.5 global illumination presented 0.8 times enhancement on the electrode with passivation coating. The reduction of surface recombination rate is responsible for the substantially improved performance, which is proposed to have originated from a decreased interface defect density in combination with a field-effect passivation induced by a negative fixed charge in the Al2O3 shells. These results not only provide a physical insight into the passivation effect, but also can be utilized as a guideline to design other energy conversion devices.
authors.affiliation: Shanghai Advanced Research Institute , Chinese Academy of Sciences, 99 Haike Road, Zhangjiang Hi-Tech Park, Pudong, Shanghai 201210, China.
authors.forename: Qunfang
authors.initials: Q
authors.lastname: Gui
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xu
authors.forename: Haifeng
authors.initials: H
authors.lastname: Zhang
authors.forename: Chuanwei
authors.initials: C
authors.lastname: Cheng
authors.forename: Xufei
authors.initials: X
authors.lastname: Zhu
authors.forename: Min
authors.initials: M
authors.lastname: Yin
authors.forename: Ye
authors.initials: Y
authors.lastname: Song
authors.forename: Linfeng
authors.initials: L
authors.lastname: Lu
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Chen
authors.forename: Dongdong
authors.initials: D
authors.lastname: Li
keywords: TiO2 nanotubes; atomic layer deposition; charge recombination; photoelectrochemical water splitting; surface passivation