Browsing by Author "Wu, Chun-Lin"

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Self-Assembled BiFeO3-epsilon-Fe2O3 Vertical Heteroepitaxy for Visible Light Photoelectrochemistry
(2016-09-21)
Le Thi Quynh
;
Chien Nguyen Van
;
Bitla, Yugandhar
;
Chen, Jhih-Wei
;
Thi Hien Do
Self-assembled vertical heterostructure with a high interface-to-volume ratio offers tremendous opportunities to realize intriguing properties and advanced modulation of functionalities. Here, a heterostructure composed of two visible-light photocatalysts, BiFeO3 (BFO) and epsilon-Fe2O3 (epsilon-FO), is designed to investigate its photoelectrochemical performance. The structural characterization of the BFO-FO heterostructures confirms the phase separation with BFO nanopillars embedded in the epsilon-FO matrix. The investigation of band structure of the heterojunction suggests the assistance of photoexcited carrier separation, leading to an enhanced photoelectrochemical performance. The insights into the charge separation are further revealed by means of ultrafast dynamics and electrochemical impedance spectroscopies. This work shows a delicate design of the self-assembled vertical heteroepitaxy by taking advantage of the intimate contact between two phases that can lead to a tunable charge interaction, providing a new confi guration for the optimization of photoelectrochemical cell.
Superior photoelectrochemical activity of self-assembled NiWO4-WO3 heteroepitaxy
(2016-05)
Thi Hien Do
;
Chien Nguyen Van
;
Tsai, Kai-An
;
Le Thi Quynh
;
Chen, Jhih-Wei
Self-assembled nanocomposites with a high interface-to-volume ratio offer tremendous opportunities of tailoring functionalities by a proper combination of components. In this study, we report the first fabrication of self-assembled NiWO4-WO3 heteroepitaxy and its excellent performance on photoel-ectrochemical water splitting. The heteroepitaxy is evidenced by a combination of x-ray diffraction and transmission electron microscopy. The energy band diagram of NiWO4-WO3 heterostructure probed by x-ray photoelectron spectroscopy suggests an efficient charge separation at their interface by injecting photo -generated electrons from NiWO4 to WO3 and holes from WO3 to NiWO4. Therefore, a great improvement in the photoelectrochemical activity of self -assembled NiWO4-WO3 heteroepitaxy was achieved (1400 mu A cm(-2) at 0.7 V vs. Ag/AgCl). This work delivers a new category of composite materials for promising photoelectrode in photoelectrochemical cells. (C) 2016 Elsevier Ltd. All rights reserved.