Metal-organic-framework-derived hierarchical Co/CoP-decorated nanoporous carbon polyhedra for robust high-energy storage hybrid supercapacitors

Electrode materials exhibiting nanostructural design, high surface area, tunable pore size, and efficient ion diffusion/transportation are essential for achieving improved electrochemical performance. In this study, we successfully prepared cobalt phosphide and cobalt nanoparticles embedded into nitrogen-doped nanoporous carbon (CoP-CoNC/CC) using a simple precipitation method followed by pyrolysis-phosphatization. Subsequently, we employed CoP-CoNC/CC as the electrode for supercapacitor applications. Notably, the resultant CoP-CoNC/CC displayed a high surface area with tunable porosity. Based on the benefits of the CoP in CoNC/CC, improved electrochemical performance was achieved with a specific capacitance of 975 F g^-1 at 1 mA cm^-2 in a 2 M KOH electrolyte. The assembled hybrid supercapacitor using CoP-CoNC/CC (positive electrode) and activated carbon (AC) (negative electrode) exhibited a specific capacitance of 144 F g^-1, a specific energy of 39.2 W h kg^-1 at 1960 W kg^-1 specific power, with better cyclic stability. The higher performance can be attributed to the synergetic effect between CoP, Co metal, and the nitrogen-doped nanoporous carbon in three-dimensional carbon cloth (CC). These excellent properties make CoP-CoNC/CC a promising electrode for developing future energy-storage devices.