Synergy of the I-/I3- redox pair in the capacitive properties of nanometric poly(3,4-ethylenedioxythiophene)

The effect of the I-/I3- redox pair electrolyte in the structural, electrochemical and capacitive properties of micrometric and nanometric PEDOT films have been examined. The thickness of the films has been found to play a key role on the capacitive properties, outstanding electrochemical properties being achieved at the nanometric scale. Electrochemical and capacitive properties were extensively investigated using cyclic voltammetry, recurrent galvanostatic pulse, chronopotentiometry and electrochemical impedance spectroscopy techniques. Results evidenced that nanometric PEDOT films exhibit very high electrochemical stabilities and excellent specific capacitances (∼185 F g−1), the latter being preserved in ∼94% after 2000 cycles in a I-/I3- -containing solution. Morphological studies revealed that the electrochemical and capacitive properties of PEDOT films are significantly influenced by their porosity, this property being relatively unaffected by the I-/I3- redox pair. The overall results allowed us to conclude that nanometric PEDOT films in presence of I-/I3- are promising candidates to be employed as supercapacitors.

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► The stability of nanometric PEDOT films in I-/I3--containing solutions is very high.
► The porosity of PEDOT is not affected by the formation of charge-transfer with iodine.
► PEDOT films in presence of I-/I3- are promising supercapacitors.