title: Co3O4-modified TiO2 nanotube arrays via atomic layer deposition for improved visible-light photoelectrochemical performance.
abstract: Composite Co3O4/TiO2 nanotube arrays (NTs) were fabricated via atomic layer deposition (ALD) of Co3O4 thin film onto well-aligned anodized TiO2 NTs. The microscopic morphology, composition, and interfacial plane of the composite structure were characterized by scanning electron microscopy, energy dispersion mapping, X-ray photoelectron spectra, and high-resolution transmission electron microscopy. It was shown that the ultrathin Co3O4 film uniformly coat onto the inner wall of the high aspect ratio (>100:1) TiO2 NTs with film thickness precisely controlled by the number of ALD deposition cycles. The composite structure with ∼4 nm Co3O4 coating revealed optimal photoelectrochemical (PEC) performance in the visible-light range (λ > 420 nm). The photocurrent density reaches as high as 90.4 μA/cm(2), which is ∼14 times that of the pristine TiO2 NTs and 3 times that of the impregnation method. The enhanced PEC performance could be attributed to the finely controlled Co3O4 coating layer that enhances the visible-light absorption, maintains large specific surface area to the electrolyte interface, and facilitates the charge transfer.
authors.affiliation: State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering and ‡State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology , Wuhan 430074, Hubei, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Yang
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Wen
authors.forename: Bin
authors.initials: B
authors.lastname: Shan
authors.forename: Rong
authors.initials: R
authors.lastname: Chen
keywords: atomic layer deposition; cobalt oxide; heterostructure; photoelectrochemical; titanium oxide; visible light