Abstract: Mesoporous manganese dioxides were prepared by a facile redox reaction using potassium permanganate (KMnO4) and polyvinyl pyrrolidone (PVP) as raw material.It is found that phases and microstructures of products are remarkably influenced by the concentration of KMnO4.As the concentration of KMnO4 increases from 0.1 mol·L-1 to 0.3 mol·L-1, the product transforms from crystalline Mn3O4 with a low surface area of 13.6 m2·g-1 to amorphous MnO2 with a relatively high surface area of 60 m2·g-1.Electrochemical tests suggest that the optimal amorphous MnO2 possesses a high specific capacitance of 442 F·g-1 at a current density of 1 A·g-1 in 2 mol·L-1 aqueous KOH electrolyte, along with 72.6;of the initial specific capacitance maintains after 1100 cycles at a current density of 5 A·g-1.

Key words: Mesoporous manganese dioxides were prepared by a facile redox reaction using potassium permanganate (KMnO4) and polyvinyl pyrrolidone (PVP) as raw material.It is found that phases and microstructures of products are remarkably influenced by the concentration of KMnO4.As the concentration of KMnO4 increases from 0.1 mol·L-1 to 0.3 mol·L-1, the product transforms from crystalline Mn3O4 with a low surface area of 13.6 m2·g-1 to amorphous MnO2 with a relatively high surface area of 60 m2·g-1.Electrochemical tests suggest that the optimal amorphous MnO2 possesses a high specific capacitance of 442 F·g-1 at a current density of 1 A·g-1 in 2 mol·L-1 aqueous KOH electrolyte, along with 72.6;of the initial specific capacitance maintains after 1100 cycles at a current density of 5 A·g-1.