Hierarchical α-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures for supercapacitors.
A facile two-step solution-phase method has been developed for the preparation of hierarchical α-MnO2 nanowires@Ni1-x Mnx Oy nanoflakes core-shell nanostructures. Ultralong α-MnO2 nanowires were synthesized by a hydrothermal method in the first step. Subsequently, Ni1-x Mnx Oy nanoflakes were grown on α-MnO2 nanowires to form core-shell nanostructures using chemical bath deposition followed by thermal annealing. Both solution-phase methods can be easily scaled up for mass production. We have evaluated their application in supercapacitors. The ultralong one-dimensional (1D) α-MnO2 nanowires in hierarchical core-shell nanostructures offer a stable and efficient backbone for charge transport; while the two-dimensional (2D) Ni1-x Mnx Oy nanoflakes on α-MnO2 nanowires provide high accessible surface to ions in the electrolyte. These beneficial features enable the electrode with high capacitance and reliable stability. The capacitance of the core-shell α-MnO2 @Ni1-x Mnx Oy nanostructures (x = 0.75) is as high as 657 F g(-1) at a current density of 250 mA g(-1) , and stable charging-discharging cycling over 1000 times at a current density of 2000 mA g(-1) has been realized.
School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore.
Hsin-Yi
HY
Wang
Fang-Xing
FX
Xiao
Le
L
Yu
Bin
B
Liu
Xiong Wen David
XW
Lou
core-shell nanostructures; nanoflakes; nanowires; supercapacitor; α-MnO2