▎ 摘　　要

The electrochemical reduction of oxygen on Pd nanoparticle-decorated nitrogen-doped graphene (Pd/NG) catalyst has been investigated in acid and alkaline solutions using the rotating disk electrode (RDE) method. The Pd/NG nanocomposites were prepared by NaBH4 reduction. The surface characterisation of Pd/NG composites was performed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The TEM images showed the uniform distribution of Pd nanoparticles over the N-doped graphene nanosheets. The RDE results indicated that Pd/NG catalysts possess a high electrocatalytic activity towards the oxygen reduction reaction (ORR). The prepared materials catalyse a 4-electron reduction of oxygen. The Tafel behaviour of O-2 reduction on Pd/NG catalysts was similar to that of bare Pd. The Pd/NG composite showed excellent ORR performance in alkaline media and is a promising material to be used as a cathode catalyst for alkaline membrane fuel cells. (C) 2014 Elsevier Ltd. All rights reserved.