Facile synthesis of flower-like α-Co(OH)2 nanostructures for electrochemical water splitting and pseudocapacitor applications

We describe a facile synthetic route to α-Co(OH)2 nanostructures by heating a solution containing CoCl2, ethylene glycol, and oleylamine. Electron microscopy and X-ray diffraction analyses revealed that flower-like nanostructures of α-Co(OH)2 were formed by assembly of thin α-Co(OH)2 nanosheets. These nanostructures exhibited high activity for electrochemical water splitting with a current density comparable to that obtained on the commercial Pt wire electrode. In addition, these flower-like α-Co(OH)2 nanostructures showed specific capacitance as high as 440 F/g at a current density of 1 A/g and excellent stability without any noticeable loss in capacitance after 5000 cycles of the galvanostatic charge–discharge test.

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