Electrocatalytic effect of the edge planes sites at graphite electrode on the vanadium redox couples

Abstract

Compared with the basal-planes of highly oriented pyrolytic graphite (HOPG), the edge-planes of HOPG exhibit a significantly enhanced electrochemical performance, indicating of the better electrocatalytic activity of the edge-planes at graphite electrode toward vanadium redox reactions, especially for the positive reaction. In order to further investigate the electrocatalytic activity of the edge plane sites, glass carbon (GC) modified by graphite powders (GP) with different particle sizes, which possess different content of the edge-planes, are used as electrodes and their physicochemical properties such as the morphology, microstructure, surface composition, and specific surface area, in addition to the corresponding electrochemical characteristics have been characterized systematically. The total electrochemical activity toward vanadium redox reaction increases greatly with the decrease of the particle sizes for GP, which mainly attributes to the increasing surface area and exposed edge plane sites. It is worth note that a large surface area often means abundant edge plane sites, and it is mainly in favor of the enhancement of the current response, while the proportion of the active area such as the edge-planes in total surface area to a large extent determines the electrocatalytic activity.