Template-assisted preparation of MnO2@MnO2 hollow nanospheres and their research of capacitance performance

MnO2@MnO2 hollow nanospheres were prepared by two-step SiO2 template method. Firstly, the core-shell structure SiO2@MnO2 ([email protected]) was prepared by hydrothermal treating SiO2 nanospheres in KMnO4 solution at 150 °C for 48 h. Then SiO2 was covered on the surface repeatedly of [email protected] to obtained SiO2@MnO2@SiO2 ([email protected]@S), and then SiO2@MnO2@SiO2@MnO2 ([email protected]@[email protected]) was formed after refluxing [email protected]@S in KMnO4 solution at 60 °C for 12 h. Finally, the SiO2 existed in both cores and the sandwich layers was etched along with immersing [email protected]@[email protected] in NaOH solution, and the MnO2@MnO2 hollow nanospheres were obtained. The electrochemical properties were measured by cyclic voltammetry (CV) and galvanic charge/discharge (GCD) using a three-electrode system in Na2SO4 electrolyte. The research results showed that the capacitance of MnO2@MnO2 with hollow structure of electrode materials was significantly increased compared with single-shelled MnO2, increasing from 210 F g−1 to 357 F g−1 at the scan rate of 5 mV s−1.