Capacitive properties of polypyrrole/activated carbon composite

Electrochemical synthesis of polypyrrole (PPy) and polypyrrole / activated carbon (PPy / AC) - composite films, with a thickness between 0.5 and 15 μm were performed in a three electrode cell containing 0.1 mol dm-3 Py, 0.5 mol dm-3 NaClO4 dissolved in ACN, and dispersed particles of AC (30 g dm-3). Electrochemical characterization of PPy and PPy / AC composites was performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The linear dependences of the capacitance (qC), redox capacitance (qred), and limiting capacitance (CL) of PPy and PPy / AC - composite films on their thickness (L), obtained by electrochemical and impedance analysis, indicate a nearly homogeneous distribution of the incorporated AC particles in the composite films (correlation coefficient between 0.991 and 0.998). The significant enhancement of qC, qred, and CL, was observed for composite films (for ∼40 ± 5%) in respect to that of the “pure” PPy. The decreased values of a volume resistivity in the reduced state of the composite film, ρ = 1.3 ⋅ 106 Ω cm (for L = 7.5 μm), for two orders of magnitude, compared to that of PPy - film with the same thickness, ρ ∼ 108 Ω cm, was also noticed.

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