Controllable synthesis of triangle taper-like cobalt hydroxide and cobalt oxide

Triangle taper-like β-Co(OH)2 and mesoporous Co3O4 microcrystals are synthesized by a simple solid-state crystal reconstruction approach. Ostwald ripening and successive dissolve-reconstruction processes were used to explain the formation mechanism. The electrochemical properties of the β-Co(OH)2 and mesoporous Co3O4 electrodes were investigated by cyclic voltammetry measurements. The specific capacitances are 137.6, 124.8, 108.8 and 98.0 F g−1 at scan rates of 5, 10, 20 and 50 mV s−1 for β-Co(OH)2; 91.5, 97.4, 90.7 and 70.9 F g−1 for Co3O4 sample at scan rates of 5, 10, 20 and 50 mV s−1. The magnetic properties also have been investigated at room temperature.