TY - JOUR
T1 - Vacuum Electrochemistry Approach to Investigate Electrical Double-Layer Capacitances of Ionic Liquid for Epitaxial Thin-Film Electrodes of TiO2 and SrO on Niobium-Doped (001)SrTiO3
AU - Takahashi, Chika
AU - Kanai, Mariko
AU - Maruyama, Shingo
AU - Matsumoto, Yuji
N1 - Funding Information:
This work was partially supported by a Giant-in Aid for Scientific Research (No. 20360294) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
Funding Information:
This work was partially supported by a Giant‐in Aid for Scientific Research (No. 20360294) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.
Publisher Copyright:
© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/8/3
Y1 - 2020/8/3
N2 - Niobium-doped (001)SrTiO3 (Nb:STO) single crystal, and epitaxial anatase (001)TiO2 and (001)SrO films, which were subsequently deposited on the Nb:STO by pulsed laser deposition, were electrochemically investigated with ionic liquid (IL) in a vacuum. After being prepared by cleaning and/or depositing the films, the electrode surfaces were characterized by observing the reflection of high-energy electron diffraction, prior to the electrochemical measurements. Electrochemical impedance spectroscopy as well as cyclic voltammetry were then performed, and the electrical double-layer (EDL) capacitance at their interfaces with the IL were successfully evaluated. The EDL capacitance of IL was several μF cm−2 for Nb:STO and gradually increased to over 10 μF cm−2 with an increase of the thickness of the deposited TiO2 films. In contrast, as SrO was being deposited, the EDL capacitance gradually decreased, approaching a constant value of about 1.4 μF cm−2, which was significantly smaller than those values achieved for TiO2 films and single-crystal Nb:STO. For different oxide/IL interfaces, a possible correlation between their measured EDL capacitance and the ionicity of the oxides is discussed.
AB - Niobium-doped (001)SrTiO3 (Nb:STO) single crystal, and epitaxial anatase (001)TiO2 and (001)SrO films, which were subsequently deposited on the Nb:STO by pulsed laser deposition, were electrochemically investigated with ionic liquid (IL) in a vacuum. After being prepared by cleaning and/or depositing the films, the electrode surfaces were characterized by observing the reflection of high-energy electron diffraction, prior to the electrochemical measurements. Electrochemical impedance spectroscopy as well as cyclic voltammetry were then performed, and the electrical double-layer (EDL) capacitance at their interfaces with the IL were successfully evaluated. The EDL capacitance of IL was several μF cm−2 for Nb:STO and gradually increased to over 10 μF cm−2 with an increase of the thickness of the deposited TiO2 films. In contrast, as SrO was being deposited, the EDL capacitance gradually decreased, approaching a constant value of about 1.4 μF cm−2, which was significantly smaller than those values achieved for TiO2 films and single-crystal Nb:STO. For different oxide/IL interfaces, a possible correlation between their measured EDL capacitance and the ionicity of the oxides is discussed.
KW - electrical double layer
KW - ionic liquids
KW - oxide electrodes
KW - pulsed laser deposition
KW - vacuum electrochemistry
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U2 - 10.1002/celc.202000620
DO - 10.1002/celc.202000620
M3 - Article
AN - SCOPUS:85086469988
SN - 2196-0216
VL - 7
SP - 3253
EP - 3259
JO - ChemElectroChem
JF - ChemElectroChem
IS - 15
ER -