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

The Raman spectroscopy study on carbonate-based electrolyte for lithium metal batteries

International audienc

Artificial nucleation sites and the study of solvation structures in electrolytes for lithium metal batteries

International audienc

Depth-resolved micro-Raman spectroscopy of tri-layer PFSA membrane for PEM fuel cells: how to obtain reliable inner water contents

International audienc

Asymmetric bi-layer PFSA membranes as model systems for the study of water management in the PEMFC

International audienc

In situ analysis of water management in operating fuel cells by confocal Raman spectroscopy

A fuel cell has been specially designed for the study of the water management in situ and operando by confocal micro-Raman spectroscopy. Water concentration profiles across the working Nafion® membrane have been extracted for different operating conditions. The characterisations performed in front of the gas distribution channel show an extreme sensitivity of the membrane water content to the local relative humidity. Electrochemical impedance spectroscopy measurements, carried out in parallel, reveal that these averaged values can be misleading when used to obtain information on the local membrane hydration state. Keywords: Fuel cell, Water management, Nafion, Raman spectroscopy, In situ analysi