A comparative study of poly(acrylic acid) and poly(styrenesulfonic acid) doped into polyaniline as platinum catalyst support for methanol electro-oxidation

Polyaniline (PANI) is doped with poly(acrylic acid) (PAA) and poly(styrenesulfonic acid) (PSS) via a doping-dedoping-redoping process. Fourier transform infrared (FT-IR) spectroscopy results confirm that PANI is doped with PSS (or PAA). X-ray photoelectron spectroscopy (XPS) results indicate that the nitrogen atoms of PANI-PSS are more positively charged than those of PANI-PAA. Scanning electron microscopy (SEM) images reveal that PANI-PSS is composed of highly porous nanowires. Platinum (Pt) can be deposited onto PANI-PAA and PANI-PSS films using the potentiostatic mode to obtain PANI-PAA-Pt and PANI-PSS-Pt composite electrodes, respectively. Auger electron spectroscopy (AES) results indicate that Pt particles disperse more uniformly into the spatial regions of PANI-PSS than those of PANI-PAA. The SO3H group in PANI-PSS may facilitate the electrodeposition of Pt better than the CO2H group in PANI-PAA. Cyclic voltammetry results and chronoamperometric response measurements show that the activity and stability toward methanol oxidation of the PANI-PSS-Pt electrode are better than those of the PANI-PAA-Pt electrode. (C) 2012 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.