Highly sensitive nanostructured platinum electrocatalysts for CO oxidation: implications for CO sensing and fuel cell performance

Abstract

Synthesis and electrochemical characterization of tailor-made nanostructured platinum catalysts efficient to oxidize dissolved carbon monoxide has been demonstrated in this work. Chemically modified electrodes using nanostructured (18 ± 0.5 nm size) platinum prepared by the electrodeposition from 0.25 M chloroplatinic acid on glassy carbon (GC) electrode shows interesting CO sensing behavior. Electrochemical oxidation of CO on this modified electrode surface has been investigated by cyclic voltammetry and stripping techniques preceded and followed by morphological and chemical characterization using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Clear evidence for CO adsorption on these Pt nanoparticles is obtained from the combined analysis of energy-dispersive and X-ray photoelectron spectroscopy data, suggesting the nature of improvement in sensitivity due to nanostructured Pt particles. Enhancement in Pt 4f binding energy (ca. 1.5 eV) suggests interesting charge transfer features, which will help to unravel the mechanism of CO sensing by these electrochemical devices. Preliminary experiments using a prototype device show excellent sensitivity (i.e. within 20-25 s in the form of an increase in current from 0.01 to 3.8 μA), and selectivity using and without a filter upon the introduction of 100 parts per million of CO in nitrogen.