Synthesis of hierarchically porous MnO2/rice husks derived carbon composite as high-performance electrode material for supercapacitors

Hierarchically porous MnO2/rice husks derived carbon (MnO2/RHC) composite with excellent electrochemical properties has been prepared as active material for supercapacitors. In this study, a two-step process was utilized for constructing this composite, involving carbonization-activation of rice husks to obtain RHC and in situ chemical precipitation to incorporate MnO2. Ultimately, MnO2 was uniformly distributed on the surface of RHC and hierarchically porous structure was well retained in the resultant MnO2/RHC composite. Based on cyclic voltammetry and galvanostatic charge-discharge measurements in 0.5 M Na2SO4 solution, MnO2/RHC composite exhibits much higher specific capacitance than that of RHC. The specific capacitance of MnO2/RHC composite reaches 197.6 F g(-1) at the scan rate of 5 mV s(-1) and 210.3 F g(-1) at the current density of 0.5 A g(-1). MnO2/RHC composite also displays favorable cycling stability with 80.2% capacitance retention after 5000 galvanostatic charge-discharge cycles. Therefore, taking advantage of the interconnected hierarchical pores that exist in its microstructure, MnO2/RHC composite is supposed to be a promising electrode material for high-performance supercapacitors. (C) 2016 Elsevier Ltd. All rights reserved.