Figure 1. Example of preferentially shaped carbon-supported or unsupported PtNi/C NPs recently synthesized at LEPMI. (a-c, e-g) STEM/X-EDS elemental maps of some nanostructures investigated in this study, high resolution TEM images with corresponding fast Fourier transform of (d) cube Pt/C and (h) hollow PtNi/C NPs.The (i) structure and the chemistry of these nanocatalysts and (ii) the ionomer content and distribution within the cathode structure will be determined at each step of the membrane-electrodes assembly (MEA) manufacturing to rationalize changes of performance in model and real PEMFC systems. A specific diagnostic toolbox, combining advanced experimental techniques and modelling, will be specifically developed and the output of this toolbox will be used to adapt the ink formulation from which the MEAs are manufactured (catalyst content and chemistry, ionomer content and chemistry, solvent composition, use of additives). Strategies to mitigate issues related to low density of catalytic sites (highly-active ORR nanocatalysts usually feature large crystallite size), incomplete wetting of the catalyst by the ionomer and poor accessibility for oxygen to the catalytic sites will be also developed. Finally, accelerated stress tests (ASTs) will be carried out. After characterisation, the results of these tests will help rationalizing why the degradation mechanisms may be different in simulated and real PEMFC operating conditions. Ultimately, the key findings of the project will be transferred to Heraeus and Symbio for industrial development.
Date of update December 7, 2019