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Operando Soft X‐ray Absorption Spectroscopic Study on a Solid Oxide Fuel Cell Cathode during Electrochemical Oxygen Reduction
Author(s) -
Nakamura Takashi,
Oike Ryo,
Kimura Yuta,
Tamenori Yusuke,
Kawada Tatsuya,
Amezawa Koji
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201700237
Subject(s) - electrochemistry , cathode , oxygen reduction , materials science , absorption (acoustics) , fuel cells , oxygen , oxide , electrochemical cell , reduction (mathematics) , inorganic chemistry , chemistry , electrode , chemical engineering , organic chemistry , metallurgy , composite material , geometry , mathematics , engineering
An operando soft X‐ray absorption spectroscopic technique, which enabled the analysis of the electronic structures of the electrode materials at elevated temperature in a controlled atmosphere and electrochemical polarization, was established and its availability was demonstrated by investigating the electronic structural changes of an La 2 NiO 4+ δ dense‐film electrode during an electrochemical oxygen reduction reaction. Clear O K‐edge and Ni L ‐edge X‐ray absorption spectra could be obtained below 773 K under an atmospheric pressure of 100 ppm O 2 /He, 0.1 % O 2 /He, and 1 % O 2 /He gas mixtures. Considerable spectral changes were observed in the O K‐edge X‐ray absorption spectra upon changing the PO2and application of electrical potential, whereas only small spectral changes were observed in Ni L‐edge X‐ray absorption spectra. A pre‐edge peak of the O K‐edge X‐ray absorption spectra, which reflects the unoccupied partial density of states of Ni 3d–O 2p hybridization, increased or decreased with cathodic or anodic polarization, respectively. The electronic structural changes of the outermost orbital of the electrode material due to electrochemical polarization were successfully confirmed by the operando X‐ray absorption spectroscopic technique developed in this study.