Implications of layer-by-layer electrodeposition of polypyrrole from a solution of the same composition for ion transport in the polymer electrode

Layer-by-layer electrodeposition of thin polypyrrole films and the charge and mass transport in the resulting multilayer polypyrrole electrodes were studied using electrochemical methods: chronoamperometry, cyclic voltammetry, quartz crystal microbalance, impedance spectroscopy. The polypyrrole/aqueous sodium hexafluoroaluminate and polypyrrole/aqueous sodium chloride systems were investigated. Polypyrrole electrodes of sub-μm total thickness were studied mostly. shown that the multilayer structure of the polypyrrole electrode results in a hindrance of charge and mass transport between the sublayers of polypyrrole prepared from a solution of the same composition. The resistance to ion transport across the polymer|polymer interface causes slower ion diffusion in the multilayer polypyrrole electrode as compared to the single-layer electrode. The redox capacitances of both structures are similar. Current traces of potentiostatic layer-by-layer deposition differ significantly for nucleation and growth of polypyrrole on polypyrrole as compared to polypyrrole on gold.