Oxygen reduction on Pd nanoparticle/multi-walled carbon nanotube composites

The electrochemical reduction of oxygen was studied on multi-walled carbon nanotube-supported palladium nanoparticle (PdNP/MWCNT) modified glassy carbon (GC) electrodes. The catalyst materials were prepared using two different methods and their electrocatalytic activity towards oxygen reduction was explored in both acid and alkaline media using the rotating disk electrode (RDE) method. Cyclic voltammetry was employed for CO stripping experiments and for the determination of real surface area of carbon nanotube-supported Pd nanoparticles. The surface morphology of PdNP/MWCNT nanocomposites was examined by transmission electron microscopy (TEM). Oxygen electroreduction kinetics were compared with those of bulk palladium electrodes. Enhanced electrocatalytic activity of PdNP/MWCNT modified GC electrodes was observed. The Tafel behaviour of oxygen reduction was similar for PdNP/MWCNT and bulk Pd electrodes. The RDE data analysis showed that the reduction of oxygen on the PdNP/MWCNT electrocatalysts studied followed a four-electron pathway.