Hydrothermal synthesis of porous Co(OH)2 nanoflake array film and its supercapacitor application

Porous α-Co(OH)2 nanoflake array film is prepared by a facile hydrothermal synthesis method. The α-Co(OH)2 nanoflake array film exhibits a highly porous net-like structure composed of interconnected nanoflakes with a thickness of 15 nm. The pseudo-capacitive behaviour of the Co(OH)2 nanoflake array film is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2 M KOH. The α-Co(OH)2 nanoflake array film exhibits high capacitances of 1017 F g − 1 at 2 A g − 1 and 890 F g − 1 at 40 A g − 1 as well as rather good cycling stability for supercapacitor application. The porous architecture is responsible for the enhancement of the electrochemical properties because it provides fast ion and electron transfer, large reaction surface area and good strain accommodation.