Electro-oxidation of formic acid using polyindole-SnO2 nanocomposite

Abstract

We report a chemical oxidative method for polyindole-tinoxide (Pin–SnO₂) synthesis and its electro-catalytic application. Our method consists of chemical polymerization of an indole monomer in the presence of dispersed nano SnO₂ at two different pHs i.e. below and above the isoelectric point of the SnO₂. Nano SnO₂ with crystallite sizes of nearly 5.0 nm are prepared by precipitation technique. For the sake of comparison, pristine polyindole is also synthesized by the same chemical method. These materials are characterized by XRD, FTIR and TEM. Characterization confirms the presence of nano SnO₂ particles in a Pin matrix and the effect of pH on the formation of a uniform nanocomposite and the extent of interaction of fillers and matrix. The electro-catalytic properties of the Pin–SnO₂ nanocomposite are investigated for formic acid oxidation using the voltammetric technique. This shows excellent synergic effect for electro-catalytic activity of the low doped Pin–SnO₂ nanocomposite (Pin–SnO₂ nanocomposite formed at higher pH). This composite is well suited for CO tolerance during the oxidation of formic acid in acidic medium and follows a direct pathway to convert it into CO₂.