Visible light driven photoelectrochemistry of self-assembled BiFeO3-ε-Fe2O3 vertical heteroepitaxy
Le Thi Quynh1*, Chien Nguyen Van1, Yugandhar Bitla1, Do Thi Hien3, Jhih- Wei Chen2, Wen-Yen Tseng4, Sheng-Chieh Liao5, Yi-Chun Chen2, Chih-Wei Luo4, Chih-Huang Lai5, Yung-Jung Hsu1, Ying-Hao Chu1
1Materials Science and engineering, National Chiao Tung University, Hsinchu, Taiwan
2Department of Physics, National Cheng Kung University, Tainan, Taiwan
3Institute of Physics, , Academia Sinica, Taipei 105, Taiwan
4Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
5Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Le Quynh,
We report on a novel self-assembled BiFeO3 (BFO) - ε-Fe2O3 (ε-FO) vertical heteroepitaxial photoelectrode for photoelectrochemical water splitting. The self-assembled vertical heterostructure BFO-FO thin films, in which the BFO nanopillars are embedded in the ε-FO matrix, are grown by pulsed laser deposition (PLD) method onto a Nb:STO(111) substrate. In this study, we examine structure, optical and electronic structure properties of BFO-FO heterojunctions with varying BFO and ε-FO mixing ratios. This heterojunction structure offers enhanced photo-conversion efficiency and better photocorrosion stability. It is observed that the designed heterostructure display better PEC performance compared to the individual counterparts due to the high surface area and improved separation of the photogenerated charge at the BFO-FO interface. This study delivers a new approach to engineer functional oxide for water splitting application.

Keywords: Composite materials, Self-assembled vertical, BiFeO3-ε-Fe2O3 heterostructures, Charge relexation