Large-area network of polyaniline nanowires supported platinum nanocatalysts for methanol oxidation

Nanocomposites comprised of Pt nanoparticles and electrically conducting polymers were prepared and tested for the electrocatalytic performance towards oxidation of methanol. Films of polyaniline (PANI) synthesized independently by potentiostatic and galvanostatic method, PANI(V) and PANI(I), respectively, were used as the supporting matrix for loading Pt nanoparticles. PANI(V), PANI(I), PANI(V)/Pt, and PANI(I)/Pt films were characterized for structure and morphology using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM image of PANI(I) reveals that the particles are highly porous and interconnected nanowires, whilst PANI(V) particles are granular. The large surface area in the nanofibrillar PANI(I) makes the dispersion of Pt particle with a lesser time for the deposition of Pt particles. The porous network structure of PANI(I) helps in effective dispersion of Pt particles (about 10-20 nm) and facilitates easy access of methanol to the catalytic sites. The electrocatalytic activity of PANI(I)/Pt is much higher (current density (24.7 mA/cm² mg) at 0.68 V) in comparison to PANI(V)/Pt and bulk Pt electrodes (the current density values of 5.5 and 7.5 mA/cm² mg).