Double layer capacitance and conductivity studies of long chain quaternary ammonium electrolytes in supercritical carbon dioxide

Abstract

This work investigates the conductivity of tetraalkylammonium tetraarylborates as a function of concentration in supercritical carbon dioxide (sc CO₂) at 70°C and 300 bar and compares the ion dissociation constants with those recently measured in cyclohexane. The double layer capacitance is also reported for the first time in a supercritical fluid and found to fit perfectly to a Helmholz model. These data are used to interpret the voltammetric response of a nickel maleonitrile complex at a platinum microelectrode in sc CO₂ and cyclohexane.