Electrocatalytic performance of carbon nanotube-supported palladium particles in the oxidation of formic acid and the reduction of oxygen

Abstract

We describe a simple approach for the synthesis of nanosized Pd particles supported on multiwall carbon nanotubes (MWCNTs) and their electrocatalytic performance in the oxidation of formic acid and the reduction of oxygen. The metal precursors are pre-organized on poly(diallyldimethylammonium) chloride-wrapped MWCNTs by electrostatic interaction and chemically reduced to obtain Pd nanoparticles. The MWCNT-supported nanoparticles are characterized by UV–visible spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy and electrochemical measurements. MWCNTs are uniformly decorated with closely packed array of nanoparticles. The nanoparticles on the MWCNTs have spherical and rod-like shapes with size ranging from 5 to 10 nm. XRD and selected area electron diffraction measurements of the nanoparticles show (1 1 1), (2 0 0) and (2 2 0) reflections of the Pd lattice. The electrocatalytic activity of the nanoparticles towards oxidation of formic acid and reduction of oxygen is examined in acidic solution. The MWCNT-supported particles exhibit excellent electrocatalytic activity. The electrocatalytic reduction of oxygen follows the peroxide pathway. Surface morphology and coverage of particles on the nanotubes control the electrocatalytic activity. The large surface area and high catalytic activity of the MWCNT-supported nanoparticles facilitate the electrocatalytic reactions at a favorable potential.