Electrochemical deposition and characterization of polypyrrole in electrolyte based on pyrrolidinium hydrogenosulfate protic ionic liquid

Abstract

In this work, we investigated the electrochemical deposition of polypyrrole (Ppy) in an electrolyte containing the pyrrolidinium hydrogenosulfate [Pyrr][HSO4] protic ionic liquid. Herein, the Ppy films were prepared by sequenced and by continuous galvanostatic deposition methods. Cyclic voltammetry (CV) and electrochemical quartz crystal microbalance techniques were further used to investigate, in each case, the polymer growth, as well as, the involved doping and dedoping processes. Additionally, atomic force microscopy, fourier transform infrared spectroscopy, CV, and electrochemical impedance spectroscopy measurements were conducted to investigate the morphology and electrochemical properties of the formed Ppy films. Similar investigations were also conducted by using the conventional aqueous electrolyte (i.e., aqueous solution containing 1 mol dm−3 of Na2SO4) to assess then the performance of the pyrrolidinium hydrogenosulfate as a medium for the electrochemical deposition of Ppy. Based on this work, we observed that the properties of Ppy, such as the capacitance, morphology, and microstructure are strongly affected by the electrolyte formulation and by the deposition technique used. Best properties of Ppy were obtained by using the sequenced galvanostatic deposition in [Pyrr][HSO4]-based electrolyte.