A new Pt-Rh carbon nitride electrocatalyst for the oxygen reduction reaction in polymer electrolyte membrane fuel cells: Synthesis, characterization and single-cell performance

摘要

In this paper the preparation of a new bimetal electrocatalyst for the oxygen reduction reaction (ORR), which is one of the most important bottlenecks in the operation of polymer electrolyte membrane fuel cells (PEMFCs), is described. This material was synthesized through a pyrolysis process of a zeolitic inorganic-organic polymer electrolyte (Z-IOPE-like) precursor, followed by suitable washing and activation procedures of the product. The electrocatalyst, whose active sites consist of platinum and rhodium, was: (a) extensively characterized from the chemical, structural, morphological and electrochemical points of view and (b) used to prepare a membrane-electrode assembly (MEA) which was tested under operative conditions in a single-cell configuration. It was observed that, with respect to a reference material based on supported platinum, rhodium did not compromise the performance of the electrocatalyst in the ORR. This behaviour was interpreted in the framework of a general model concerning the enhancement of ORR performance in bimetal systems supported on carbon nitrides. Finally, the material shows a slightly better tolerance toward a few common contaminants for the ORR such as methanol and chloride anions, typical of direct methanol fuel cells (DMFCs) and vehicular applications, respectively.