Photoexcited Hole Transfer to a MnOx Cocatalyst on a SrTiO3 Photoelectrode during Oxygen Evolution Studied by In Situ X-ray Absorption Spectroscopy

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• 作者：Masaaki Yoshida ; Takumi Yomogida ; Takehiro Mineo ; Kiyofumi Nitta ; Kazuo Kato ; Takuya Masuda ; Hiroaki Nitani ; Hitoshi Abe ; Satoru Takakusagi ; Tomoya Uruga ; Kiyotaka Asakura ; Kohei Uosaki ; Hiroshi Kondoh
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 23, 2014
• 年：2014
• 卷：118
• 期：42
• 页码：24302-24309
• 全文大小：562K
• ISSN：1932-7455

文摘

Photoexcited hole transfer to MnO_x cocatalysts on SrTiO₃ photoelectrodes was examined under controlled potential conditions during UV irradiation using in situ Mn K-edge X-ray absorption fine structure (XAFS) spectroscopy. The absorption edges of spectra were found to shift to higher energies during irradiation, indicating that MnO_x cocatalysts were oxidized by the migration of photoexcited holes accompanied by a positive potential shift of the MnO_x cocatalysts. This oxidation process was promoted by the application of a positive applied potential, suggesting that the photoexcited hole transfer was enhanced by upward band bending at the cocatalyst鈥損hotoelectrode interface. Structural changes of the MnO_x cocatalyst were found to depend on the UV photon intensity; thus, the observations of photoexcited electron transfer by XAFS are associated with the photoelectrochemical activity during water splitting.