Nitrogen-Doped Hierarchical Porous Carbon through One-Step Activation of Bean Curd for High-Performance Supercapacitor Electrode

New nitrogen-doped hierarchical porous carbons (HPCs) with large surface areas were prepared from bean curd through a one-step impregnation activation method at 750 degrees C with CH3COOK as an activating agent. The porous carbons were characterized by a variety of techniques such as N-2-sorption analysis, scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy. The results show that there are numerous macropores with a pore size of approximate to 200 nm observed by SEM and TEM as well as micropores probed by N-2-sorption analysis, indicating a hierarchical porous structure for these carbon materials. The effect of activating agent dosage on the porous structure of carbon was carefully investigated. The Brunauer-Emmett-Teller specific surface area and nitrogen content for the optimized carbon are 2180 m(2)g(-1) and 2.62 at%, respectively. As evidenced by electrochemical measurements, the as-prepared carbon has a good capacitive performance and the specific capacitance is calculated to be 284 Fg(-1) at a current density of 0.1 Ag-1 in KOH electrolyte. More importantly, this carbon could deliver a high capacitance up to 118 Fg(-1) at a very high current density of 30 Ag-1 due to its hierarchical porous structure, which will facilitate the ion transfer under high current density. Our research highlights the potential application of these HPCs as high-performance electrode materials for electric double-layer capacitors.