Electrochemical behavior of [UO2C14]2- in 1-ethyl-3-methylimidazolium based ionic liquids

In order to examine the chemical form of uranyl species in l-ethyl-3-methylimidazolium （EMI） based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2CI4] into a mixture of EMICI and EMIBF4 （50：50 tool%） were measured. As a result, it was confirmed that uranyl...

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Bibliographic Details
Published in:Science China. Chemistry 2012-09, Vol.55 (9), p.1699-1704
Main Authors: Ogura, Toshinari, Sasaki, Kotoe, Takao, Koichiro, Arai, Tsuyoshi, Ikeda, Yasuhisa
Format: Article
Language:English
Subjects:
Absorption spectra
Acetonitrile
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Diffusion coefficient
Diffusion rate
Electrochemical analysis
Electrodes
Ionic liquids
Mixtures
Silver nitrate
乙基
可见吸收光谱
扩散系数
扫描速度
氧化还原电对
甲基咪唑
电化学行为
离子液体
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Summary:In order to examine the chemical form of uranyl species in l-ethyl-3-methylimidazolium （EMI） based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2CI4] into a mixture of EMICI and EMIBF4 （50：50 tool%） were measured. As a result, it was confirmed that uranyl species in the mixture of EMICI and EMIBF4 existed as [UO2C14]2-. Cyclic voltammograms （CVs） of [UO2CI4]2- in the mixture were measured at 25 ~C using a Pt working electrode, a Pt wire counter electrode, and an Ag/Ag＋ reference electrode （0.01 M AgNO3, 0.1 M tetrabutylammonium perchlorate in acetonitrile） in a glove box under an Ar atmosphere. Peaks corresponding to one redox couple were observed around -1.05 V （Epc） and -0.92 V （Epa） vs. ferrocene/ferrocenium ion （Fc/Fc＋）. The potential differences between two peaks （AEp） increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s-1, while the （Epc ＋ Epa）/2 value was constant, -0.989 V vs. Fc/Fc＋ regardless of the scan rate. Furthermore, the diffusion coefficient of [UO2C14]2 and the standard rate constant were es- timated to be 3.7× 10^-8 cm^2 s 1 and （2.7-2,8） × 10^-4 cm s-! at 25 ℃. By using the diffusion coefficient and the standard rate constant, the simulation of CVs was performed based on the reaction, [UO2C14]2- ＋ e- = [UO2C14]3-. The simulated CVs were found to be consistent with the experimental ones. From these results, it is concluded that [UO2C14]2- in the mixture of EMIC1 and EMIBF4 is reduced to [UO2C14]3- quasi-reversibly at -0.989 V vs. Fc/Fc＋.
ISSN:1674-7291
1869-1870
DOI:10.1007/s11426-012-4693-8