Synthesis, studies and fuel cell performance of core-shell electrocatalysts for oxygen reduction reaction based on a PtNix carbon nitride shell and a pyrolyzed polyketone nanoball core

This report describes a new class of core-shell electrocatalysts for oxygen reduction reaction (ORR) processes for application in Proton Exchange Membrane Fuel Cells (PEMFCs). The electrocatalysts are obtained by supporting a shell consisting of PtNix alloy nanoparticles embedded into a carbon nitride matrix (indicated as PtNix-CN) on a core of pyrolyzed polyketone nanoballs, labeled 'STp'. ST(p)s are obtained by the sulfonation and pyrolysis of a precursor consisting of XC-72R carbon nanoparticles wrapped by polyketone (PK) fibers. The ST(p)s are extensively characterized in terms of the chemical composition, thermal stability, degree of graphitization and morphology. The core-shell ORR electrocatalysts are prepared by the pyrolysis of precursors obtained impregnating the STp cores with a zeolitic inorganic-organic polymer electrolyte (Z-IOPE) plastic material. The electrochemical performance of the electrocatalysts in the ORR is tested in situ by single fuel cell tests. The interplay between the chemical composition, the degree of graphitization of both PtNix-CN shell and STpS cores, the morphology of the electrocatalysts and the fuel cell performance is elucidated. The most crucial preparation parameters for the optimization of the various features affecting the fuel cell performance of this promising class of ORR electrocatalysts are identified. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.