期刊
APPLIED SURFACE SCIENCE
卷 479, 期 -, 页码 137-147出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2019.02.018
关键词
Self-limiting mechanism; Heterostructure; Ferroelectricity; Oxygen evolution; Water splitting; Soft X-ray absorption
类别
资金
- National Natural Science Foundation of China [51627901]
- National Key Research and Development Program of China [2016YFA0401004, 2017YFA0402904]
- Anhui Initiative in Quantum Information Technologies [AHY100000]
- Open Programs for the Key Science & Technology Infrastructures of Chinese Academy of Sciences
Oxygen evolution is the bottleneck step in the photocatalytic water splitting process, which can be settled by intentionally constructing a designed heterojunction and specially tuning the interface structure. Herein Bi6Fe2Ti3O18-BiOBr (BFTO/BOB) heterostructure with intimate 2D/2D interfaces are successfully grown by converting part of ferroelectric BFTO nanosheets to BOB via an ion-exchange chemical reaction. For the first time, it is discovered that the conversion of BFTO to BOB is a self-limiting process, i.e., the reaction auto-stops at a certain ratio of BFTO/BOB even high concentration of reactants (hydrobromic acid) are used. This phenomenon is ascribed to the precipitation-dissolution equilibrium due to the higher solubility product constant of BiOBr. The fine 2D/2D structure of ferroelectric BFTO/BOB with good energy band alignment leads to two times and seven times higher oxygen evolution rates than non-ferroelectric BFTO/BOB and pure BFTO under full-spectrum irradiation, respectively. The promoted separation and transfer of photogenerated electron-hole pairs at the interface is clarified by the soft X-ray absorption spectroscopies, Mott-Schottky curves and photocurrent tests. What's more, the ferroelectric spontaneous polarization at the interface between the ferroelectric BFTO and the BiOBr also shows a synergetic effect for the oxygen evolution enhancement. Our finds may open up new windows to prepare 2D/2D heterostructures with improved photocatalytic activities.
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