Porous glassy carbon formed by rapid pyrolysis of phenol-formaldehyde resins and its performance as electrode material for electrochemical double layer capacitors

摘要

In this article, we report a modified pyrolysis technique featuring an ultra-fast pyrolysis for obtaining a new type of high surface area glassy carbon (GC) from lithographically patterned novolac type phenol-formaldehyde resin, SU8. The fast-pyrolysis chemistry of SU8 is responsible for the formation of bubbles in the carbonizing matrix, which ultimately leads to the observed morphological changes. This porous glassy carbon (PGC) pyrolyzed at a heating rate of 50 degrees C/min has been evaluated as an electrode material for electrochemical double layer capacitors employing electrochemical techniques such as cyclic voltammetry (CV) and chronoamperometry. The electrochemically available surface area of PGC electrodes is found to be similar to 3 times greater compared with flat GC electrodes, and the electrode and specific capacitance improvements are 15 and 5 times, respectively. We describe possible mechanisms that may influence the enhanced capacitor performance of PGC electrodes, and compare their capacitance at five different potential scan rates ranging from 5 to 75 mV/s. In addition, the effect of H2SO4 surface treatment on the electrochemistry of the thus pyrolyzed carbons is investigated. Other possible applications of the thus obtained PGC are also discussed in the concluding remarks. (C) 2014 Elsevier B.V. All rights reserved.