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.
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.
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