Synthesis and electrochemical properties of semicrystalline gyroidal mesoporous MnO2

Mesoporous silica KIT-6 has novel three-dimensional gyroidal channel structure, space group of Ia-3d, and ordered tunable pores up to 10 nm. In this paper, such mesostructured silica was employed as hard template to prepare semicrystalline gyroidal mesoporous MnO2. The structure was investigated by XRD, TEM and HRTEM, and found to be of high quality Ia-3d symmetry, in good accordance with the template structure. The material has a BET surface of 118 m(2)center dot g(-1) and pore volume of 0.35 cm(3)center dot 9(-1) after eliminating template. Mesoporous MnO2 has shown good electrochemical property as supercapacitor material in l mol center dot L-1 Na2SO4 and l mol-L-1 LiClO4 solutions, but interesting pseudocapacitance behavior was observed in the case of 6 mol center dot L-1 KOH. It was found that mesoporous MnO2 performed stable reversible electrochemical behavior with capacitance of 220 F center dot g(-1) in a potential range of -0.1-0.55 V vs. Hg/HgO in alkaline solution, demonstrating that it is a promising novel electrode material for the fabrication of electrochemical capacitors.