Electrochemical capacitive behaviors of ordered mesoporous carbons with controllable pore sizes

Ordered mesoporous carbons (OMCs) with controllable pore sizes in the range of 4-10 nm are prepared by a template procedure using 2D hexagonal MSU-H and 3D cubic KIT-6 as hard templates and boric acid as the pore expanding agent. The electrochemical performances of the as-synthesized OMCs as electrode materials for electrochemical double layer capacitors (EDLCs) are characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GC) and electrochemical impedance spectroscopy (EIS) experiments in 30 wt% KOH electrolyte. The influence of the pore size distributions of OMCs on the electrochemical capacitive performances is discussed. The prepared OMCs exhibit good capacitive behaviors with the specific capacitance values ranging from 143 to 205.3 F g(-1) at a voltage scan rate of 5 mVs(-1) and 81 to 86% retained at a high scan rate of 100 mVs(-1). OMC-M-2 shows the highest specific surface capacitance value of 27.5 mu F cm(-2) at 5 mVs(-1) with a peak pore size of 7.8 nm and a Brunauer-Emmet-Teller (BET) surface area of 729.3 m(2) g(-1). The analysis of two kinds of pore symmetries of OMCs with the same pore size of about 6.5 nm shows that the 3D cubic OMC exhibited superior capacitive performance than the 2D hexagonal OMC. (C) 2012 Elsevier B.V. All rights reserved.