Oxygen reduction reaction at few-layer graphene structures obtained via plasma-assisted electrochemical exfoliation of graphite

Abstract

Few-layer graphene structures with a surface decorated with oxygen functional groups and sulfur-containing groups have been obtained during electrochemical exfoliation of graphite performed in the cathodic and anodic plasma modes. Conductivity of a synthesized carbon material has been estimated and its catalytic activity towards the oxygen reduction reaction has been studied. For the few-layer graphene structures synthesized in the anodic plasma mode, a considerable catalytic effect has been observed, which involved decrease in overpotential of the oxygen reduction and increase in contribution of a four-electron oxygen reduction in the overall process. This effect is shown to be determined by the surface carbonyl groups which are the active centres of the four-electron oxygen reduction at potentials less than −700 mV vs. Ag/AgCl.