Hierarchical TiO2 nanobelts@MnO2 ultrathin nanoflakes core–shell array electrode materials for supercapacitors

Abstract

Hierarchical TiO₂ nanobelts@MnO₂ ultrathin nanoflakes core–shell arrays (TiO₂@MnO₂ NBAs) have been fabricated on a Ti foil substrate by hydrothermal approach and further investigated as the electrode for a supercapacitor. Their electrochemical properties were examined using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in a three-electrode cell. The experimental observations clearly show that the fabricated TiO₂@MnO₂ NBAs electrode possesses superior rate capability and outstanding cycling performance due to its rationally designed nanostructure. A specific capacitance as high as 557.6 F g⁻¹ is obtained at a scan rate of 200 mV s⁻¹ (454.2 F g⁻¹ at a current density of 200 mA g⁻¹) in 1 M Na₂SO₄ aqueous solution. The energy density and power density measured at 2 A g⁻¹ are 7.5 Wh kg⁻¹ and 1 kW kg⁻¹ respectively, demonstrating its good rate capability. In addition, the composite TiO₂@MnO₂ NBAs electrode shows excellent long-term cyclic stability. The fabrication method presented here is facile, cost-effective and scalable, which may open a new pathway for real device applications.