Hexamethylenetetramine-assisted morphological evolution of nanowire-net and nanosheet-structured cobalt hydroxide

Publication date: 1 November 2019Source: Materials Letters, Volume 254Author(s): Kyung Ho Kim, Sena Motoyama, Yoshio Abe, Midori Kawamura, Takayuki KibaAbstractNanowire-net and nanosheet-structured cobalt hydroxide (Co(OH)2) was prepared directly on a fluorine-doped tin oxide (FTO)-coated glass substrate using aqueous solutions of cobalt nitrate hexahydrate (10 mM) and hexamethylenetetramine (HMT, 2–30 mM), synthesized at 60 °C. With increasing HMT amount, the morphology changed from nanowire-net to nanosheet, resulting from the promotion of growth under sufficient OH− ions provided by the HMT. The binder-free Co(OH)2 sample prepared with 30 mM HMT showed a good areal specific capacitance of ∼60 mF/cm2 at a scan rate of 2 mV/s, as well as excellent capacity retention (∼84% over 5000 cycles). The proposed facile method allows the morphological engineering of Co(OH)2 nanostructures with superior electrochemical performance.Graphical abstract
Source: Materials Letters - Category: Materials Science Source Type: research