A Comparative Study of the Electrochemical Characteristicsof [Emim~+][BF4~-] and [Bmim~+][BF4~-] Ionic Liquids at the Surfacesof Carbon Nanotube and Glassy Carbon Electrodes

摘要

The electrochemical interfaces of a glassy carbon (GC) electrode and a carbon nanotube (CNT) paper electrode have been studied in l-ethyl-3-methylimidazolium tetrafluor-oborate (EmimBF4) and l-butyl-3-methylimidazolium tetra-fluoroborate (BmimBF4) ionic liquids (ILs) using direct current (DC) cyclic voltammetry (CV) and alternating current (AC) electrochemical impedance spectroscopy (EIS). These four electrode/electrolyte combinations serve as representative models of the relatively unconventional, spatially inhomoge-neous IL-carbon interfaces that are potentially useful for electrochemical energy-storage/conversion devices. The present work explores in detail the double-layer capacitances as wellas other essential electrochemical features of these interfaces. The voltage-dependent double-layer capacitances, and the interfacial charge transfer resistances have been determined within the nonfaradaic windows of these systems, independently, by using CV and EIS. The results of the DC and AC measurements have been compared to demonstrate how the material properties of such complex systems can affect their characterization procedures if they are simply treated as classical ideally polarized interfaces.