A facile one-step approach to hierarchically assembled core–shell-like MnO₂@MnO₂ nanoarchitectures on carbon fibers: An efficient and flexible electrode material to enhance energy storage

Hierarchical core–shell-like MnO₂ nanostructures (NSs) were used to anchor MnO₂ hexagonal nanoplate arrays (HNPAs) on carbon cloth (CC) fibers. The NSs were prepared by a novel one-step electrochemical deposition method. Under an external cathodic voltage of -2.0 V for 30 min, hierarchical core–shell-like MnO₂-NS-decorated MnO₂ HNPAs (MnO₂ NSs@MnO₂ HNPAs) were uniformly grown on CC with reliable adhesion. The phase purity and morphological properties of the samples were characterized by various physicochemical techniques. At a constant external cathodic voltage, growth of MnO₂ NSs@MnO₂ HNPAs on CC was carried for different time periods. When utilized as a flexible, robust, and binder-free electrode for pseudocapacitors, the hierarchical core–shell-like MnO₂ NSs@MnO₂ HNPAs on CC showed clearly enhanced electrochemical properties in 1 M Na₂SO₄ electrolyte solution. The results indicate that the MnO₂ NSs@MnO₂ HNPAs on CC have a maximum specific capacitance of 244.54 F/g at a current density of 0.5 A/g with excellent cycling stability compared to that of bare MnO₂ HNPAs on CC (112.1 F/g at 0.5 A/g current density). We believe that the superior charge storage performance of the pseudocapacitive electrode can be mainly attributed to the hierarchical MnO₂ NSs@MnO₂ HNPAs building blocks that have a large specific surface area, offering additional electroactive sites for efficient electrochemical reactions. The facile and single-step approach to growth of hierarchical pseudocapacitive materials on textile based electrodes opens up the possibility for the fabrication of high-performance flexible energy storage devices.