Hydrothermal synthesis of mesoporous metal oxide arrays with enhanced properties for electrochemical energy storage

Mesoporous nanowall NiO arrays are prepared by a facile hydrothermal synthesis method with a following annealing process. The NiO nanowall shows continuous mesopores ranging from 5 to 10 nm and grows vertically on the substrate forming a porous net-like structure with macropores of 20–300 nm. A plausible mechanism is proposed for the growth of mesoporous nanowall NiO arrays. As cathode material of pseudocapacitors, the as-prepared mesoporous nanowall NiO arrays show good pseudocapacitive performances with a high capacitance of 600 F g−1 at 2 A g−1 and impressive high-rate capability with a specific capacitance of 338 F g−1 at 40 A g−1. In addition, the mesoporous nanowall NiO arrays possess good cycling stability. After 6000 cycles at 2 A g−1, a high capacitance of 660 F g−1 is attained, and no obvious degradation is observed. The good electrochemical performance is attributed to its highly porous morphology, which provides large reaction surface and short ion diffusion paths, leading to enhanced electrochemical properties.