Fabrication of a novel nanohybrid via the introduction of Ni/Mn-LDH into Ni-MOFs/MWCNTs for high-performance electrochemical supercapacitor

Layered double hydroxide (LDH), as an electrode material, consists of positively charged layers and interlayer hydrated anions and is endowed with promising prospects in supercapacitors (SCs) due to its large specific surface area, tunable metal ions, abundant redox active sites, and low cost. Moreover, metal-organic frameworks (MOFs) exhibit adjustable pore sizes, while multi-walled carbon nanotubes (MWCNTs) boast exceptional electrical conductivity. Hence, in this work, flower-like nickel/manganese layered double hydroxide (Ni/Mn-LDH) was introduced into nanohybrid of MWCNTs decorated with nickel metal-organic frameworks (Ni-MOFs/MWCNTs) to fabricate a novel Ni-MOFs/MWCNTs@Ni/Mn-LDH nanohybrid as electrode material for SCs using a two-step solvothermal method. In the composite structure of the novel Ni-MOFs/MWCNTs@Ni/Mn-LDH nanohybrid, the flower-like assembly of Ni/Mn-LDH nanosheets was seamlessly integrated with MWCNTs adorning the Ni-MOFs, creating an interconnected hierarchical porous network. This distinctive structure, coupled with the synergistic effects of its components, facilitated the swift diffusion of electrolyte ions. Furthermore, it enhanced the accessibility to more active sites at the interfaces during the redox process, thereby contributing considerably to an improved electrochemical performance. The specific capacity of the Ni-MOFs/MWCNTs@Ni/Mn-LDH nanohybrid as electrode material obtained at the optimal experimental conditions was 1151.0C g−1 at 1.0 A g−1. The assembled asymmetric supercapacitor (ASC) had an energy density of 25.6 Wh kg−1 at a power density of 845.3 W kg−1. The fabrication strategy of the Ni-MOFs/MWCNTs@Ni/Mn-LDH could be extended to synthesize other nanohybrid.