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

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 mu m), flexible, have a uniform distribution of metallic Ag nanoparticles and exhibit electrical conductivity (similar to 1.5 S cm(-1)). The thick (similar to 200 mu m) PPy-Ag films prepared at the bottom of the beaker exhibit lower conductivity (similar to 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.