Fabrication and electrochemical characteristics of nanowire-net structured cobalt hydroxide

Abstract

Cobalt hydroxide (Co(OH)2) nanostructures were prepared on fluorine-doped tin oxide (FTO) substrates via an inexpensive and simple wet-chemical method. At a growth temperature of 60 °C, heterogeneous nucleation caused the nanowire-net structured Co(OH)2 to form a compact bottom layer on the surface of FTO substrate, and homogeneous nucleation resulted in the growth of a porous nanowire-net layer in the solution as the top layer. At 90 °C, vertically well-aligned Co(OH)2 nanosheets were grown from the heterogeneous nucleation on the surface of FTO substrate. Cyclic voltammetry (CV) revealed that the entirely binder-free Co(OH)2 prepared at 60 °C had a high capacitance of 254F/g (38.08 mF/cm2) at a scan rate of 2 mV/s and good rate capability compared to the nanosheet-structured Co(OH)2 prepared at 90 °C. Furthermore, it had excellent long-term electrochemical stability of ∼97% after 1000 cycles at a scan rate of 50 mV/s. These results suggested that the nanowire-net structured Co(OH)2 had significant application potential in the field of energy storage.