Cactus-like NiCoFe-LDH-Se/NiCo-O-Se nanoarrays with the controllable tuning of active sites and structures for high-performance hybrid supercapacitors

Layered double hydroxides (LDHs) are widely used in supercapacitors due to their high theoretical capacity and environmental friendliness, however, the limited active sites are still the main factor limiting the improvement of their electrochemical performance. Herein, heteroatom doping and structure modulation strategies can improve the reactivity of LDH nano-arrays. Novel cactus-like nanostructures NiCoFe-LDH-Se/NiCo-O-Se with abundant active sites and controllable morphology were synthesized for the first time. The special structure provides multidimensional channels for rapid charge transfer. In addition, in-situ selenization can effectively modulate the electronic structure and expose multiple redox active sites, which ultimately accelerates the reaction kinetic rate and enables NiCoFe0.75-LDH-Se/NiCo-O-Se to exhibit excellent electrochemical performance (394.13 mAh g-1, 1 A g-1). Meanwhile, the assembled device NiCoFe0.75-LDH-Se/NiCo-O-Se//AC (activated carbon) exhibits high energy density (72.3 Wh kg-1 at 800 W kg-1) and stable cycling performance. Thus, this work provides ideas for preparing high-performance 3D nanomaterials.