Pt-based multi-metallic nanoparticle electrocatalysts show considerable catalytic properties to accelerate the sluggish kinetics of the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). The ORR activity can be tuned by chemical composition, particle size and shape of the Pt-based nanoparticles. However, the durability of the Pt-based multi-metallic electrocatalysts is still a crucial challenge due to the gradual (electro)chemical dissolution of the less noble metal under fuel cell conditions.
In this talk, I will show that the structural parameters (such as nature of the metal, initial atomic ratio, initial particle size, particle shape and morphology) as well as the experimental parameters (such as scan rate, potential range and electrolyte) strongly influence the (electro)chemical resistance of these Pt-based bimetallic nanoparticles. I will present a broad overview about different promising Pt-based electrocatalyst concepts for PEFC application and show the critical parameters to control and to stabilize the less noble metal. Since the ORR is a surface-sensitive reaction, I show how to link the knowledge about the UHV-treated single crystals and the industrial spherical nanoparticles by using shape-controlled nanoparticles. In-situ and ex-situ high-resolution spectroscopic and microscopic techniques such as scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDX) as well as synchrotron-based X-ray absorption spectroscopy (XAS) are used in our research to provide more insights into the atomic processes of Pt-based electrocatalysts under electrochemical ORR conditions.
Our goal is to better understand the electrochemical processes on bimetallic nanoparticles and to provide strategies to improve the activity and long-term durability of Pt-based nanoparticle electrocatalysts for the ORR.