Birnessite-type MnO2 nanosheet arrays with interwoven arrangements on vapor grown carbon fibers as hybrid nanocomposites for pseudocapacitors.

Manganese dioxide nanosheet arrays with interconnected arrangements are easily synthesized on vapor grown carbon fibers (MnO2 NSAs@VCFs) by a simple wet-chemical method at low temperature. The conductive nature of the VCFs serves as a scaffold and easily reduces potassium permanganate species for the formation of hierarchical MnO2 NSAs@VCFs. When utilized as an electroactive material for pseudocapacitors, the sophisticated configuration of the nanocomposite provides an effective electrochemical activity and an electron pathway for higher electrochemical performance in 1 M Na2SO4 aqueous solution. The hierarchical MnO2 NSAs@VCFs exhibit a maximum specific capacitance of 115.3 F g-1 at a current density of 0.5 A g-1 with an excellent cycling stability of 85.6% after 2000 cycles at a current density of 5 A g-1. Such facile and cost-effective fabrication of a metal oxide nanocomposite with improved electrochemical performance allows it to be considered as a promising electroactive material for energy storage devices.