Date: Oct 8, 2018

Abstract

An electrochemically activated graphite electrode (EAGE) was obtained by a simple and moderate method of anodic potentiostatic polarization. The composition, microstructure, and electrochemical properties of the EAGE were characterized by high-resolution X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the electrochemical activity and the reversibility for electrode processes of V(II)/V(III) and V(IV)/V(V) couples on the EAGE are significantly improved due to the introduced C[double bond, length as m-dash]O and COOH groups. The rate constant of charge transfer for the anodic oxidation of V(IV) on the EAGE was determined to be 8.17 × 10−4 cm s−1, which is about 20 times larger than the 4.09 × 10−5 cm s−1 rate constant on the pristine graphite electrode.

Graphical abstract: An electrochemically activated graphite electrode with excellent kinetics for electrode processes of V(ii)/V(iii) and V(iv)/V(v) couples in a vanadium redox flow battery

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