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On the Study of PEM Fuel Cells by Transmission Electron Microscopy

The long-term efficiency of proton exchange membrane fuel cells (PEMFC) is largely restricted by the instability of catalyst nanoparticles during fuel cell operation. Due to their large surface area-tovolume ratio, Pt and Pt-alloy nanoparticles have a strong tendency to grow in size over short time scales, which lead to a reduction in their electrochemically-active surface area, and consequently to an undesired catalyst deactivation and reduction in cell performance after several cycles [1]. Yet, it is still unclear what the main degradation mechanism is, particularly whether modified Ostwald ripening or coalescence is predominant for particle growth within the cathode.