Beta-manganese dioxide nanoflowers self-assembled by ultrathin nanoplates with enhanced supercapacitive performance

Abstract

Hierarchical porous β-MnO₂ nanoflowers self-assembled by ultrathin (thickness less than 10 nm) nanoplates have been successfully fabricated at room temperature. Because of its high specific surface area (267 m² g⁻¹) and proper pore size distributions (average pore size, ca. 5.9 nm), the obtained 3D nanomaterials achieve enhanced capacitance as high as 296.3 F g⁻¹ at a scanning rate of 2 mV s⁻¹, which is ∼20 times of those of the traditionally prepared nanostructural β-MnO₂ (e.g. 1D hollow β-MnO₂ nanorods with ∼14.9 F g⁻¹). Furthermore, it has an appreciable ability to deliver large energy densities at high rates (67.4% capacitive retention). The comparable property with α-MnO₂ indicates that such low-cost porous β-MnO₂ nanoflowers may also be a very promising candidate material for supercapacitors besides lithium battery material.