Mesoporous MnO 2 synthesized by using a tri-block copolymer for electrochemical supercapacitor studies

Abstract

Mesoporous MnO 2 is prepared from KMnO 4 by using a tri-block copolymer, namely, poly(ethylene glycol)–block-poly(propylene glycol)–block-poly(ethylene glycol) (PEG–PPG–PEG) as a reducing as well as a structure-directing agent. The as synthesized MnO 2 samples are poorly crystalline with mesoporosity having pore diameter between 8 and 40 nm. BET surface area as high as 273 m 2 g −1 is obtained. By heating, the poorly crystalline MnO 2 turns into a well crystalline form at 400 °C with nanorod morphology. However, the surface area decreases for the heated samples. Samples of MnO 2 prepared by varying the ratio of KMnO 4 and the copolymer, and also the heated samples are subjected to electrochemical characterization for supercapacitor studies. High specific capacitance values on mass basis are obtained for the as prepared mesoporous MnO 2 samples.