Electric double-layer capacitors based on highly graphitized nanoporous carbons derived from ZIF-67

Nanoporous carbons (NPCs) have large specific surface areas, good electrical and thermal conductivity, and both chemical and mechanical stability, which facilitate their use in energy storage device applications. In the present study, highly graphitized NPCs are synthesized by one-step direct carbonization of cobalt-containing zeolitic imidazolate framework-67 (ZIF-67). After chemical etching, the deposited Co content can be completely removed to prepare pure NPCs with high specific surface area, large pore volume, and intrinsic electrical conductivity (high content of sp²-bonded carbons). A detailed electrochemical study is performed using cyclic voltammetry and galvanostatic charge-discharge measurements. Our NPC is very promising for efficient electrodes for high-performance supercapacitor applications. A maximum specific capacitance of 238 F-g^-1 is observed at a scan rate of 20 mV-s^-1. This value is very high compared to previous works on carbon-based electric double layer capacitors. Highly graphitized nanoporous carbons (NPCs) are synthesized by one-step direct carbonization of cobalt-containing zeolitic imidazolate framework-67 (ZIF-67). After chemical etching, the deposited Co nanoparticles are completely removed to prepare pure NPCs with high specific surface area, large pore volume, and intrinsic electrical conductivity. The specific energy of the NPC-based supercapacitor reached 19.6 W-h-kg^-1 at a specific power of 700 W-kg^-1 (see figure).