Preparation of Pt/poly(aniline-co-orthanilic acid) nanocomposites and their applications for electrocatalytic oxidation of methanol

Abstract

Copolyanilines containing various molar feed ratios of aniline (Ani) and orthanilic acid (Oaa) units are chemically synthesized using ammonium persulfate as an oxidant. The structure and morphology of the poly(aniline-co-orthanilic acid)s are characterized using Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The XPS results show that a saturated doping state is achieved when the Ani/Oaa molar feed ratio is less than 20/1. The SEM images reveal that the copolyaniline films are composed of highly porous nanowires when the feed molar ratio of Ani/Oaa is more than 4/1. The poly(aniline-co-orthanilic acid)s are used as Pt catalyst supports. Transmission electron microscopy (TEM) results show that Pt particles disperse more uniformly onto the highly porous nanowires of P(Ani10-co-Oaa1) (feed molar ratio = 10:1) than onto other copolyanilines. The electrocatalytic behaviors of copolyaniline-Pt electrodes toward the oxidation of methanol are studied using cyclic voltammetry. Among the copolyaniline-Pt electrodes studied, the P(Ani10-co-Oaa1)-Pt electrode shows the highest electrocatalytic activity for methanol oxidation.