A Reactive Template Synthesis of Hierarchical Porous Carbon and Its Application to Supercapacitor Electrodes

Hierarchical porous carbons (HPCs) are highly in demand as electrode materials for efficient supercapacitors. Herein, a modified template carbonization approach in conjunction with chemical activation is described for synthesis of HPCs by direct one-pot pyrolysis of a mixture of glucose (G), reactive template precursor (Zn₂(OH)₂CO₃)(BZC), and K₂CO₃ (PC) in which in situ ZnO produced from decomposition of Zn₂(OH)₂CO₃ acts as template and K₂CO₃ as activator, followed by simple acid-leaching. The resultant undoped carbon [HPC(G-BZC-PC)] is endowed with coral reef-like morphology, 3D porous networks, numerous micro/mesopores, ultrahigh surface area, and goodelectrical conductivity. The specific capacitance delivered by a two-electrode symmetric supercapacitor with the HPC(G-BZC-PC) achieves 241.2 F g⁻¹ at 1 A g⁻¹, which is superior to that of the two control samples prepared without addition of BZC and PC, respectively. Furthermore, the rate capability reaches as high as to 90.5% and 74.6% with current density from 1 to 10 A g⁻¹ and 50 A g⁻¹, respectively, and an excellent cycling stability is observed with more than 98% of retention after 10 000 cycles at 5 A g⁻¹ in 6 m KOH. It is concluded that a cooperative effect deriving from the above-mentioned unique features contributes to the enhanced supercapacitor performance.