The proposed ECs are extensively characterized both before and after A to study the complex interplay between the synthetic parameters, the physicochemical properties, and the electrochemical ORR performance both “ex-situ” and in single PEMFC. In this regard, particular attention is dedicated to clarify the role played by the graphene nanoplatelets included in the H-GR support. Inductively-coupled plasma atomic emission spectroscopy (ICP-AES) and CHNOS microanalyses are adopted to determine the bulk chemical composition of the ECs. The surface composition and oxidation states are probed with X-ray photoelectron spectroscopy (XPS), while the structure of the ECs is investigated through wide-angle X-ray diffraction (WAXD) and vibrational spectroscopies (e.g., confocal micro-Raman). High-resolution transmission electron microscopy (HR-TEM) is used to study the morphology. Cyclic voltammetry with the rotating ring-disk electrode (CV-TF-RRDE) allows the details of the ORR performance and mechanism to be elucidated. Finally, the ECs are used to fabricate membrane-electrode assemblies (MEAs) that are tested in single PEMFC in operating conditions.
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 696656. The authors thank the Strategic Project “From materials for Membrane electrode Assemblies to electric Energy conversion and SToRAge devices” (MAESTRA) of the University of Padova for funding this research.
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