Facile synthesis of ultralong MnO2 nanowires as high performance supercapacitor electrodes and photocatalysts with enhanced photocatalytic activities

Abstract

A simple hydrothermal route was developed for the synthesis of uniform α-MnO₂ nanowires using a controllable redox reaction in a MnCl₂–KMnO₄ aqueous solution system. Electrochemical properties of the resulting products as an electrode were investigated by cyclic voltammetry, chronopotentiometry and electrochemical impedance tests. The electrode can provide a specific capacitance of 180 F g⁻¹ at a current density of 1.0 A g⁻¹. After 2000 cycles, the specific capacitance was maintained above 78%. Besides, the as-synthesized products were also used as the photocatalyst for the photocatalytic degradation of several dye molecules. The results show almost complete degradation (~99%) of Congo red dye molecules in 30 min. Such ultralong MnO₂ nanowires are expected to have potential applications in wastewater treatment and energy storage.