A multidimensional micro CuCo2O4/nano NiMoO4 architecture is prepared on Ni foam by the hydrothermal method. The structure consists of urchinlike CuCo2O4 microspheres covered by ultrathin NiMoO4 nanosheets. The synergistic effect depends on the diversity of space and composition. The one-dimensional CuCo2O4 nanoneedles enhance the charge transport and carry the two-dimensional NiMoO4 nanosheets. The nanosheets can expose abundant active sites and act as an armor to alleviate the volume change and maintain the structural integrity during long-term cycling. The three-dimensional skeleton integrates the intrinsic properties and external spatial effect of each component. The corresponding supercapacitor exhibits a high specific capacity of 276 mAh g–1 at 1 A g–1, good rate capability, and excellent cycling stability of 98.3% over 8000 cycles. The concept of integrating the multidimensionality and multicomponent provides a universal approach to develop high-performance materials.

The different morphologies of CuCo2S4 have a significant effect on the electrocatalytic activity. However, the reasons for the activity difference of catalysts with multiple morphologies have raised little concern. Herein, we put forward the concept of “active edge perimeter” to evaluate the relative number of active sites. The morphologies are regulated by arranging NH4F from 0 to 3 mmol to prepare microsheet, tight‐binding microsheet, hybrid microsheet/wire, long microwire and short wire morphologies. The long‐perimeter microsheets can achieve a low Tafel slope (89 mV dec−1) and overpotential (283 mV) to reach a current density of 20 mA cm−2 for the oxygen evolution reaction. For microsheets, the charge‐transfer resistance is well under 50 % of the average values. The electrochemical surface area is above average area, owing to the high double‐layer capacitance. Therefore, for two‐dimensional microsheets, the long active perimeter is the main reason it ensures the high activity required for hierarchical catalysts.

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Uniform CuO microspheres were successfully synthesized through a simply surfactant-free hydrothermal synthesis assisted by a soluble long-alkyl-chain tetraalkylammonium carboxylic copper salt. During the synthetic procedure, a botallackite-type Cu2(OH)3Br intermediate with 3D bamboo-leaf-like structure was obtained by careful time-controlled experiments. Subsequently, the intermediate was converted into CuO spheres via a solid-phase transformation competed with a dissolution–renucleation process. Additionally, ion-adjusted experiments were manipulated to analyze the effects on CuO morphologies of the various of ionic groups involved in the long-alkyl-chain tetraalkylammonium carboxylate. It confirms that the organic copper salt precursor used in this work not only supplies a constant copper source for crystal growth of CuO but also plays an important role in the spherical architecture building as a self-surfactant agent.