Enhanced supercapacitive performances of hierarchical porous nanostructure assembled from ultrathin MnO2 nanoflakes

Abstract

Ultrathin mesoporous nanoflakes of α-MnO2 films were easily prepared by mixing potassium permanganate (KMnO4) with hydrochloric acid in an aqueous solution. The obtained α-MnO2 has a tunnel structure composed of an edge-shared network of [MnO6] octahedra. Scanning electron micrograph observations revealed that the obtained MnO2 materials have 2D frameworks which consisted of highly porous interconnected nanoflakes. TEM image shows that the ultrathin nanoflakes almost have the thickness about 3–5 nm. Nitrogen desorption analyses showed that these ultrathin MnO2 nanoflakes exhibited large surface area up to 102 m2 g−1. The electrochemical performances of the synthesized α-MnO2 ultrathin nanoflakes as supercapacitor electrode materials were studied by cyclic voltammetry cycling in 1 M Na2SO4 solution. The result showed that mesoporous MnO2 with 2D frameworks exhibit a high capacitance of 328 Fg−1 with 84 % stability for 1000 cycles. Thus, the obtained ultrathin α-MnO2 nanoflakes are suitable for its use as supercapacitor electrode materials.