10.17 : ボルタンメトリー: 概要

In voltammetry, the current flowing through an electrochemical cell is measured as a function of applied potential under conditions of concentration polarization.

The voltammetric cell comprises three electrodes immersed in a dilute solution of the analyte along with a supporting electrolyte.

A potentiostat varies the working electrode's potential relative to the reference electrode. The resulting current is recorded against the working electrode potential as a voltammogram.

Working electrodes in voltammetry have minimal surface areas to enhance polarization.

Generally, mercury working electrodes are preferred for their relatively large negative potential range because of the high overvoltage of hydrogen on mercury.

Additional advantages include amalgam formation and the ability to renew the electrode surface by new drop formation.

In dilute solutions, the current that results when an electroactive species is reduced or oxidized reaches a limiting value directly proportional to the analyte's concentration. By measuring voltage and current at the interface between the electrode and an electroactive analyte, voltammetry reveals information about the reduction or oxidation processes of the analyte.