Electrochemical investigations in Imidazolium based ionic liquids

Abstract

Room Temperature Ionic Liquids (RTILs) are a new class of solvents receiving increasing attention for their possible use as alternative solvent/electrolyte to conventional electrolytes in electrochemical setups. Due to their wide electrochemical window, appreciable conductivity, ability to dissolve wide range of organic and inorganic substrates, low vapour pressure, high chemical and thermal stability and above all ability to stabilize transient species, RTILs are considered as excellent media for ecofriendly, innovative and sustainable electrochemistry. Besides all the advantageous features RTILs do have, their wide spread use for electrochemical investigations and applications is yet to be realized. Some practical concerns associated with use of RTILs in electrochemical setups and a lack of complete understanding about their role as solvent/electrolytes in electron transfer and the associated reactions are the main reasons that currently hamper their use for electrochemical investigations and applications. In this regard some fundamental aspects related to RTILs, like equilibrium and transport properties of pure RTILs and alteration of these properties through use of cosolvents or variations in experimental parameters, specialities of electrode/RTIL interfaces over that of the electrode/conventional electrolyte solution interfaces, impact of RTIL specific effects on heterogeneous electron transfer and associated chemical reactions need some detailed investigations. Work presented in this thesis is an attempt to have a better understanding about some of these challenges one comes across, while working with RTIL based electrochemical setups. Electrochemistry of model redox systems was explored to test the validity of established theories in RTILs and to realize the potential advantages of RTILs over conventional solvents. Solvent dynamic control over transport, charge transfer processes and ion pair effects are discussed. The advantageous aspects due to solvent specific effects of RTILs over thermodynamic, kinetic and mechanistic aspects of heterogeneous electron transfer and associated reactions are also discussed.