タイトル（掲載誌）The Journal of Physical Chemistry C
一般注記A simple electrode reaction provides negative values of the double layer (DL) capacitance because a dipole of electrochemically generated charge coupled with the imaged charge on the electrode is oriented in the direction opposite to that of solvent. Some properties such as dependence of the capacitive values on the dc potentials, the frequency dependence, and localization of the redox charge are herein discussed in order to comprehend the negative capacitance. The redox species used are a ferrocenyl derivative, hexaammineruthenium, and hexachloroiridium, of which heterogeneous reaction rates are so fast that the faradaic currents should be controlled by diffusion or the Warburg impedance. The observed ac current can be represented by a simple sum of the diffusion-controlled current and the DL charging current by solvent and that by the redox species. Subtraction of the observed imaginary part of the admittance from the real one eliminates the diffusion contribution to extract the charging admittance. This admittance takes negative values at dc potentials near the standard redox potential. It is formulated by the dipole of the redox charge paired with the mirror-imaged charge. The negative capacitance has frequency dispersion similar to the conventional DL capacitance. A pseudocapacitor has enhanced cooperatively the charge from the sum of individual DL charge and the redox charge, but this advantage is open to discussion.
著作権情報〓 2018 American Chemical Society
連携機関・データベース国立情報学研究所 : 学術機関リポジトリデータベース（IRDB）（機関リポジトリ）