Electrochemical investigation of free-standing polypyrrole–silver nanocomposite films: a substrate free electrode material for supercapacitors

Abstract

We report a facile route for synthesis of free standing polypyrrole–silver (PPy–Ag) nanocomposite films by photopolymerization of pyrrole using AgNO₃ as photosensitizer in aqueous medium. In this process PPy–Ag films were formed at the air–water interface and at the bottom of the beaker. The films formed at the air–water interface are thin (≤2 μm), flexible, have a uniform distribution of metallic Ag nanoparticles and exhibit electrical conductivity (∼1.5 S cm⁻¹). The thick (∼200 μm) PPy–Ag films prepared at the bottom of the beaker exhibit lower conductivity (∼0.15 S cm⁻¹). Interestingly, the more conductive thin PPy–Ag films exhibit a low specific capacitance of 58 F g⁻¹ as compared to the specific capacitance of 282 F g⁻¹ for the thicker PPy–Ag films at a 1 mV s⁻¹ scan rate in 0.5 M K₂SO₄ electrolyte. The better electrochemical activity and high specific capacitance of the thicker PPy–Ag films is attributed to their porous structure, which provides a larger electrolyte accessible conductive surface for redox reactions. This simple approach for the synthesis of PPy–Ag films along with their promising electrochemical properties allows their possible application as a substrate free electrode material for supercapacitors.