Synthesis of rich N-doped hierarchically porous carbon flowers for electrochemical energy storage

Designed as electrode material for high performance supercapacitor, rich N-doped hierarchically porous carbon flowers (CU) were successfully prepared through a simple urea-carbonization/activation method by using polydopamine as carbon source and flower-like ZnO as template, respectively. The effect of added urea amount during carbonization/activation process on the doped nitrogen content, morphology and microstructures as well as electrochemical properties of CU samples were further investigated. Stemmed from hierarchically flower-like structure, rich nitrogen content of 13 wt% and high specific surface area of 666 m(2) g(-1), the optimal sample CU2 exhibited high reversible capacity and excellent rate performance, delivering a specific capacitance of 187 F g(-1) at current density of 1 A g(-1). Even up to 40 A g(-1), a rate specific capacity of 144 F g(-1) could be obtained. Moreover, by using this N-doped hierarchically porous carbon flower as electrode material, the assembled supercapacitor displayed excellent energy density and power density as well as remarkable cycling stability with 92% of capacitance retention after 10,000 cycles.