Synthesis of Birnessite-Type MnO_(2) by the In-Situ Electrochemical Oxidation of Mn_(3)O_(4) Film for Supercapacitors

摘要

Here we report an in situ electrochemical oxidation method to synthesize birnessite-type MnO_(2) electrodes for supercapacitors from cathodically deposited Mn_(3)O_(4) thin films. Mn_(3)O_(4) thin films composed of nanowall arrays with a porous structure were prepared by cathodic deposition at various temperatures. Nanoparticles were formed within the nanowalls when the deposition temperature is above 50 deg C, building a nanoparticle/porous hierarchy architecture. Cyclic voltammogram (CV) was used to perform electrochemical oxidation on the Mn_(3)O_(4) thin film. The birnessite-type MnO_(2) phase was successfully achieved after the electrochemical CV cyclings, which is believed to be responsible for the significant increase in the specific capacitance of the supercapacitor.