Comparative studies on electrochemical activity of graphene nanosheets and carbon nanotubes

This study compares the electrochemical activity of four kinds of carbon materials, i.e. single-walled carbon nanotubes (SWNTs), pristine graphene oxide nanosheets (GONs), chemically reduced GONs, and electrochemically reduced GONs, with potassium ferricyanide (K3Fe(CN)(6)), beta-nicotinamide adenine dinucleotide (NADH) and ascorbic acid (AA) as the redox probes. Cyclic voltammetry (CV) results demonstrate that the electron transfer kinetics of the redox probes employed here at the carbon materials essentially depend on the kind of the materials, of which the redox processes of the probes at SWNTs and electrochemically reduced GONs are faster than those at the pristine and chemically reduced GONs. The different electron transfer kinetics for the redox probes at the carbon materials studied here could be possibly ascribed to the synergetic effects of the surface chemistry (e.g., C/O ratio, presence of quinone-like groups, surface charge, and surface cleanness) and conductivity of the materials. This study could be potentially useful for understanding the structure/property relationship of the carbon materials and, based on this, for screening and synthesizing advanced carbon materials for electrochemical applications. (C) 2009 Elsevier B.V. All rights reserved.