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 (S@M) was prepared by hydrothermal treating SiO2 nanospheres in KMnO4 solution at 150 degrees C for 48 h. Then SiO2 was covered on the surface repeatedly of S@M to obtained SiO2@MnO2@SiO2(S@M@S), and then SiO2@MnO2@SiO2@MnO2 (S@M@S@M) was formed after refluxing S@M@S in KMnO4 solution at 60 degrees C for 12 h. Finally, the SiO2 existed in both cores and the sandwich layers was etched along with immersing S@M@S@M 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). (C) 2019 Elsevier B.V. All rights reserved.