Preparation and electrochemical characterization of MnOOH nanowire-graphene oxide

► MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 °C, with MnO2-graphene oxide composites which are synthesized by a redox reaction between KMnO4 and graphene oxide. ► MnO2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. ► It is found that the electrochemical resistance of MnOOH nanowire-graphene oxide composites decreases and the capacitance increases to 76 F g−1 when hydrothermal reaction is conducted in ammonia aqueous solution. ► MnOOH nanowire-graphene oxide composites prepared by hydrothermal reaction in 5% ammonia aqueous solution have excellent capacitance retention ratio at scan rate from 5 mV s−1 to 40 mV s−1.