MOF derived CoP-decorated nitrogen-doped carbon polyhedrons/reduced graphene oxide composites for high performance supercapacitors

Abstract

ZIF-67 derived CoP-decorated nitrogen-doped porous carbon (CoP-NPC) polyhedra anchored on reduced graphene oxide (RGO) sheets have been successfully prepared through an efficient pyrolysis–phosphidation–assembly strategy. The resulting CoP-NPC/RGO composite as an electrode for supercapacitors shows an enhanced electrochemical performance with high capacitances of 466.6 F g⁻¹ at 1 A g⁻¹ and 252 F g⁻¹ at 20 A g⁻¹, as well as 94.7% of capacitance retention after 10 000 cycles in 1 M H₂SO₄ solution. Moreover, the symmetrical two-electrode device assembled from CoP-NPC/RGO electrodes delivers a high energy density of 12 W h kg⁻¹ at a power density of 500 W kg⁻¹ and excellent long-term cycling stability (93% of the initial capacitance after 10 000 cycles at 10 A g⁻¹). This superior electrochemical performance of CoP-NPC/RGO can be ascribed to its 3D interconnected porous structure and the synergistic effect between CoP and the nitrogen-doped carbon matrix. The unique architecture of the composites can effectively enhance the electrochemical performance by shortening the diffusion distance of electrolyte ions and improving the electrical conductivity and the contact area between active materials and the electrolyte. The excellent electrochemical performances make CoP-NPC/RGO a promising electrode material for high-performance supercapacitors.