Electrical and electrochemical properties of imidazolium and phosphonium-based pNIPAAM ionogels

The electrical and electrochemical properties of two ionogel materials based on the poly(N-isopropylacrylamide) gel with 1-ethyl-3-methylimidazolium ethyl sulfate and trihexyltetradecylphosphonium dicyanamide ionic liquids are investigated. The current-voltage curves show a current rectification for both ionogels and ionic liquids after inducing ion adsorption on gold electrode surface. The polymer matrix of the ionogels mitigates ion adsorption, resulting in lower rectification ratios when comparing with the corresponding ionic liquids. The stability and the electrochemical window (ECW) of the ionogels are calculated from cyclic voltammograms and compared with the ones obtained for the ionic liquids. The widest electrochemical window is achieved by the phosphonium ionic liquid and its ionogel. Finally, the effect of the absorbed atmospheric water and the mutual coefficient diffusion of the redox active species inside the IO is calculated. This work widens the knowledge of the behavior of ionogel materials characterized on gold electrode interfaces. (C) 2020 Elsevier Ltd. All rights reserved.