Fast synthesis of δ-MnO2 for a high-performance supercapacitor electrode

We report a very simple and fast route for a high capacitive birnessite type manganese dioxide (delta-MnO2) synthesis, fully suitable to be applied as electrode in redox-based electrochemical supercapacitors. The material was obtained from a very efficient chemical reduction of potassium permanganate by nascent hydrogen in low temperature acid media. delta-MnO2 was extensively characterized by several techniques confirming the obtainment through the proposed route. The supercapacitive properties of the novel structure were evaluated showing a specific capacitance of 190 F g(-1) at 0.25 A.g(-1). In addition, to the best of our knowledge, this is the first report regarding the chemical synthesis of delta-MnO2 with no dependence of hazardous reducing agent, high temperature or high pressure commonly used to metal oxides production.