Interfacial Synthesis of δ-MnO₂ Nano-sheets with a Large Surface Area and Their Application in Electrochemical Capacitors

Birnessite-type MnO₂ (δ-MnO₂) nano-sheets were successfully synthesized by an interfacial synthesis method in this work. The properties and electrochemical performance of the as-prepared δ-MnO₂ were analyzed and evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption measurement and electrochemical tests. This facile synthesis method enables δ-MnO₂ nano-sheets to show a large specific surface area (257.5 m² g^-1). The electrochemical test results show that the specific capacitance is 272 F g^-1 and the specific capacitance retention is over 96.7% after 1000 cycles at a scan rate of 10 mV s^-1. All results demonstrate that δ-MnO₂ has a great potential application in high-performance electrochemical capacitors, and this interfacial synthesis method will be a very promising method to synthesize highly active MnO₂ materials in a large scale. © 2015.