MnO₂ Density - Dependent Supercapacitive Characteristics of SiO₂/MnO₂ Core-shell Nanostructure

摘要

A simple approach has been developed to fine-tune SiO2 spheres into low-density SiO2 spheres withthe total volume increased by etching in a NaBH4 solution, followed by the preparation of theSiO2/MnO2 and low-density SiO2/MnO2 core-shell nanocomposites. The core-shell nanocompositeswith uniform diameters from 200 to 350nm can be observed on scanning electron microscopy (SEM)and transmission electron microscopy (TEM). With the reaction time increasing, the thickness ofmanganese oxide shells around the silica core thickens, while the electrochemical properties areobserved to present a parabola style. Interestingly, the low-density SiO2/MnO2 core-shell-1 nanocomposites deliver the maximum specific capacitance of 298.3 F g far more than the SiO2/MnO2-1 core-shell nanocomposites (179.8 F g ), and possess desirable electrochemical stability (5000 cyclesretained 86.3%). All of these findings indicate that the low-density SiO2/MnO2 core-shellnanostructures appear to be a promising electrode material for supercapacitors application.