Measurement of Counter Electrode Potential during Cyclic Voltammetry and Demonstration on Molten Salt Electrochemical Cells
D. Sri Maha Vishnu *
Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India and Materials Chemistry Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, United Kingdom
N. Sanil
Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India
K. S. Mohandas
Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India
*Author to whom correspondence should be addressed.
Abstract
In conventional cyclic voltammetry (CV) measurements, the potential of the working electrode (WE) is changed at a fixed scan rate w.r.t a reference electrode and the current response to the potential stimuli recorded. The current-potential data are in turn related to the redox behavior of the electro-active species in the electrolyte on the WE. The contribution of the counter electrode (CE) to the electrical signals has been suppressed by design to avoid its influence on the I-V characteristics of the WE. However, simultaneous measurement of the counter electrode potentials during CV measurements can provide useful qualitative information on the electrochemical process/es occurring at the CE and thus help in the comprehensive assessment of the overall electrochemical process/es under question. This has been demonstrated with tungsten and graphite WEs respectively against graphite and molybdenum CEs in CaCl2-x wt.% CaO melts (x = 0 and 1) at 1173 K. The technique has been applied to CV cell with Nb2O5 pellet as the WE against graphite CE in CaCl2 melt and the results prove that preliminary information on the electro-deoxidation of the oxide electrode could be achieved by the novel measurements.
Graphical abstract
Keywords: Cyclic voltammetry, Counter electrode potential, Calcium chloride, Nb2O5, FFC Cambridge process, Electro-deoxidation