Small Particles of Chemically-Reduced Graphene with Improved Electrochemical Capacity

Abstract

Chemically reduced graphenes (CRGs) of different sizes were prepared by the reduction of graphene oxide (GO) in different oxidation degrees, with hydrazine hydrate as the reducing agent. Compared with normally oxidized GO (46.9 wt %), the deeply oxidized GO particles have a higher oxygen content (50.4 wt %). The oxygen content of resulting CRG is correspondingly increased from 11.3 wt % of normal-sized CRG to 16.3 wt % of small-sized CRG, with a dramatic increase in specific surface area from 468.2 to 716.3 m2/g. More graphene edges, which were highly decorated by pseudocapacitive-active sites, were exposed in the small-sized CRG. As a result, small-sized CRG has a much higher specific capacitance (192.1 F/g) than that of normal-sized CRG (132.3 F/g), which is attribute to the contribution of both electrochemical double layer capacitance by an increased surface area and pseudocapacitance by extra surface functional groups.