標題: Fully Depleted Ti-Nb-Ta-Zr-O Nanotubes: Interfacial Charge Dynamics and Solar Hydrogen Production
作者: Chiu, Yi-Hsuan
Lai, Ting-Hsuan
Chen, Chun-Yi
Hsieh, Ping-Yen
Ozasa, Kazunari
Niinomi, Mitsuo
Okada, Kiyoshi
Chang, Tso-Fu Mark
Matsushita, Nobuhiro
Sone, Masato
Hsu, Yung-Jung
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: Ti-Nb-Ta-Zr-O;nanotube arrays;solar water splitting;fully depleted;interfacial charge dynamics
公開日期: 11-Jul-2018
摘要: Poor kinetics of hole transportation at the electrode/electrolyte interface is regarded as a primary cause for the mediocre performance of n-type TiO2 photoelectrodes. By adopting nanotubes as the electrode backbone, light absorption and carrier collection can be spatially decoupled, allowing n-type TiO2, with its short hole diffusion length, to maximize the use of the available photoexcited charge carriers during operation in photoelectrochemical (PEC) water splitting. Here, we presented a delicate electrochemical anodization process for the preparation of quaternary Ti-Nb-Ta-Zr-O mixed-oxide (denoted as TNTZO) nanotube arrays and demonstrated their utility in PEC water splitting. The charge transfer dynamics for the electrodes was investigated using time-resolved photoluminescence, electrochemical impedance spectroscopy, and the decay of open-circuit voltage analysis. Data reveal that the superior photoactivity of TNTZO over pristine TiO2 originated from the introduction of Nd, Ta, and Zr elements, which enhanced the amount of accessible charge carriers, modified the electronic structure, and improved the hole injection kinetics for expediting water splitting. By modulating the water content of the electrolyte employed in the anodization process, the wall thickness of the grown TNTZO nanotubes can be reduced to a size smaller than that of the depletion layer thickness, realizing a fully depleted state for charge carriers to further advance the PEC performance. Hydrogen evolution tests demonstrate the practical efficacy of TNTZO for realizing solar hydrogen production. Furthermore, with the composition complexity and fully depleted band structure, the present TNTZO nanotube arrays may offer a feasible and universal platform for the loading of other semiconductors to construct a sophisticated heterostructure photoelectrode paradigm, in which the photoexcited charge carriers can be entirely utilized for efficient solar-to-fuel conversion.
URI: http://dx.doi.org/10.1021/acsami.8b00727
http://hdl.handle.net/11536/145271
ISSN: 1944-8244
DOI: 10.1021/acsami.8b00727
期刊: ACS APPLIED MATERIALS & INTERFACES
Volume: 10
起始頁: 22997
結束頁: 23008
Appears in Collections:Articles