Freestanding Co 3O 4 nanowire array for high performance supercapacitors

Abstract

We report a single-crystalline Co 3O 4 nanowire array grown on a nickel foam prepared by a hydrothermal synthesis method for supercapacitor application. The Co 3O 4 nanowires show sharp tips and have an average diameter of 70 nm, and a length up to 25 μm. Impressively, the as-prepared single-crystalline Co 3O 4 nanowire array exhibits noticeable pseudocapacitive performance with a high capacitance of 754 F g -1 at 2 A g -1 and 610 F g -1 at 40 A g -1 as well as excellent cycling stability. The enhanced supercapacitor performance is due to the unique one-dimensional (1D) architecture, which provides fast diffusion paths for ions and facilitates the electron and ion transfer on the Co 3O 4/electrolyte interfaces. Moreover, the 1D nanowire array can accommodate the volume expansion and restrain the pulverization and deterioration of Co 3O 4 during the repeated cycling process, resulting in enhanced cycling stability. © 2012 The Royal Society of Chemistry.