N-Doped Graphitized Hierarchical Porous Carbon Aerogel as an Electrode Material for Supercapacitors

Electrode materials are the key factors determining the performance of supercapacitors. An N-doped graphitized hierarchical porous carbon aerogel (NGHC) was prepared through freeze-drying and heat treatment of the zeolitic imidazolate framework-67 (ZIF-67)/sodium carboxymethyl cellulose (CMC)/potassium tris (oxalato) ferrate(III) trihydrate (K₃[Fe(C₂O₄)₃]) composite. In this process, ZIF-67 served as a precursor to generate N-doped porous carbon through thermal activation, and CMC acted as a binder linking carbon particles from ZIF-67 to form a continuous conductive framework. K₃[Fe(C₂O₄)₃] acted as both an activator and a catalyst, helping to develop porosity and graphitization. The resulting NGHC possessed a unique structure: a hierarchical pore structure, a high surface area, good conductivity, and a large number of N heteroatoms. Due to the synergistic effect of these factors, NGHC demonstrated a high specific capacitance of 261 F/g at 1 A/g in a three-electrode system. When employed in a supercapacitor, it delivered a superior energy density output of 18.75 Wh/kg at 1000 W/kg. These results reveal that NGHC is a potential electrode material in a supercapacitor.