Stepwise Splitting Growth and Pseudocapacitive Properties of Hierarchical Three-Dimensional Co(3)O(4) Nanobooks

Three-dimensional hierarchical Co(3)O(4) nanobooks have been synthesized successfully on a large scale by calcining orthorhombic Co(CO(3))(0.5)(OH)·0.11H(2)O precursors with identical morphologies. Based on the influence of reaction time and urea concentration on the nanostructures of the precursors, a stepwise splitting growth mechanism can be proposed to understand the formation of the 3D nanobooks. The 3D Co(3)O(4) nanobooks exhibit excellent pseudocapacitive performances with specific capacitances of 590, 539, 476, 453, and 421 F/g at current densities of 0.5, 1, 2, 4, and 8 A/g, respectively. The devices can retain ca. 97.4% of the original specific capacitances after undergoing charge–discharge cycle tests 1000 times continuously at 4 A/g.