Preparation, characterization and single-cell performance of a new class of Pd-carbon nitride electrocatalysts for oxygen reduction reaction in PEMFCs

This report describes the preparation of two Pd-based carbon nitride electrocatalysts for the oxygen reduction reaction (ORR) for application in polymer electrolyte membrane fuel cells (PEMFCs). The electrocatalysts consist of multi-metallic active sites supported on a graphite-like carbon nitride (CN) matrix with a N content exceeding 13 wt%. The electrochemical performance is investigated by cyclic voltammetry with the thin-film rotating disk electrode method (CV-TF-RDE) and evaluated in a single membrane electrode assembly (MEA) PEMFC. The correlation of the structural information to functional properties allows to propose a reaction mechanism and to identify the most desirable features to achieve in a CN electrocatalyst in order to obtain desired electrochemical performance in catalysis of ORR. It is established also that the CN support improves the tolerance towards the catalyst corrosion under oxidizing conditions and thus improves the catalyst durability. The stoichiometry and the morphology of Pd-based CN electrocatalysts play a crucial role in the modulation of the tolerance towards common ORR poisons such as chlorine anions and methanol. Finally, the performance of the Pd-based CN electrocatalysts in a single MEA PEMFC proved promising.