Electrochemical Reduction of Oxygen on Heat-Treated Pd Nanoparticle/Multi-Walled Carbon Nanotube Composites in Alkaline Solution

Palladium nanoparticle/multi-walled carbon nanotube (PdNP/MWCNT) composites were prepared using magnetron sputtering of Pd followed by heat treatment at different temperatures. The oxygen reduction experiments were performed to evaluate the PdNP/MWCNT catalyst activity for fuel cell cathodes in 0.1 M KOH solution. Scanning electron microscopy was employed to examine the changes in surface morphology of the PdNP/MWCNT composites upon annealing. Electrochemical behaviour of the prepared PdNP/MWCNT catalysts was investigated using cyclic voltammetry and the rotating disk electrode (RDE) methods. The RDE results revealed that the PdNP/MWCNT composite annealed at 500 °C is the most active catalyst for the four-electron reduction of O2, and specific activity of this material is higher than that of bulk Pd.