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 MnO 2 . The structure was investigated by XRD, TEM and HRTEM, and found to be of high quality Ia‐ 3 d symmetry, in good accordance with the template structure. The material has a BET surface of 118 m 2 ·g ‐1 and pore volume of 0.35 cm 3 ·g −1 after eliminating template. Mesoporous MnO 2 has shown good electrochemical property as supercapacitor material in 1 mol·L −1 Na 2 SO 4 and 1 mol·L −1 LiClO 4 solutions, but interesting pseudocapacitance behavior was observed in the case of 6 mol·L −1 KOH. It was found that mesoporous MnO 2 performed stable reversible electrochemical behavior with capacitance of 220 F·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.