Electroreduction of oxygen on Vulcan carbon supported Pd nanoparticles and Pd-M nanoalloys in acid and alkaline solutions

The kinetics of O₂ reduction on novel electrocatalyst materials deposited on carbon substrates were studied using the rotating disk electrode (RDE) technique. Palladium nanoparticles and Pd-M (PdCo and PdFe) nanoalloys supported on Vulcan XC-72R were prepared using two different synthetic routes. The catalyst samples were examined by transmission electron microscopy (TEM) and the average size of metal nanoparticles was determined. Electrochemical measurements were performed in 0.5 M H₂SO₄ and in 0.1 M NaOH solutions. The influence of different synthetic conditions on the values of specific activity and other kinetic parameters was investigated. These parameters were determined from the Tafel plots taking into account the real electroactive area for each electrode. Pd nanoparticles and Pd-M nanoalloys exhibit significantly high electrocatalytic activity for the four-electron reduction of oxygen to water.