Capacitive behavior of graphene-ZnO composite film for supercapacitors

Graphene-ZnO composite film was synthesized for its potential application in supercapacitors. Graphene was prepared by a modified Hummers method and hydrazine reduction process, and ZnO was deposited on graphene by ultrasonic spray pyrolysis. The electrochemical characteristics of the film were investigated through electrochemical impedance spectrometry, cyclic voltammetry and chronopotentiometry tests. The results showed that graphene-ZnO composite film exhibited an enhanced capacitive behavior with better reversible charging/discharging ability and higher capacitance values, by comparison to pure graphene or ZnO electrode. (C) 2009 Elsevier B.V. All rights reserved.