Transformation of 2D Co-LDH into 3D hierarchical hollow Co₃O₄ polyhedral arrays with enhanced electrochemical performance for supercapacitors

The designed construction of hierarchical porous materials with a large surface area can be potentially used to improve electrochemical properties in supercapacitors. In this study, a facile approach involving the in situ transformation of two dimensional (2D) ultrathin cobalt layered double hydroxide (Co-LDH) into 3D co-based metal organic frameworks (Co-MOFs) on conductive carbon cloth. Carbonizing and oxidizing strategy are subsequently adopted to convert the Co-MOFs precursor into 3D hollow Co₃O₄ polyhedral arrays. Owing to the 3D hollow architecture of the Co₃O₄ arrays are uniformly distributed on carbon cloth, which can provide more reaction sites, fast electron transport, and high electrochemical activity. The optimized 3D Co₃O₄-60@CC as a binder free electrode delivers high specific capacitance of 806 F g⁻¹ at the current density of 1 A g⁻¹ as well as excellent cycling stability. In addition, the assembled asymmetric device Co₃O₄-60@CC//AC achieves high energy density of 25.3 W h kg⁻¹ at the power density of 752 W kg⁻¹ and still retains 86.5% of the performance after 4000 cycles.