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

Abstract 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 SO 3 H group in PANI–PSS may facilitate the electrodeposition of Pt better than the CO 2 H 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.