PtFeNi tri-metallic alloy nanoparticles as electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells with ultra-low Pt loading

In this paper we demonstrated a three step method to prepare nanoengineered PtFeNi alloy based catalyst with ultra-low Pt loading for proton exchange membrane fuel cells (PEMFCs). This method involves firstly the electro-deposition of FeNi alloy onto porous carbon electrode substrate, secondly, the galvanic displacement process to form PtFeNi alloy, and lastly the excess Fe and Ni surface atoms were selectively dissolved in a chemically-coupled electrochemical process. The core–shell structured PtFeNi alloy composed of a multi-layer Pt-rich shell and a Pt-poor core was finally produced and characterized by various methods. Scanning electron microscopy (SEM) of electrode surface revealed that the carbon blacks are covered with extremely high density of nano-catalysts, while electron dispersive X-ray detector (EDX) confirmed that these catalysts are indeed PtFeNi. The as-prepared PtFeNi ternary alloy electro-catalyst based electrodes were used as the cathodes in fuel cell and presented a good performance and stability with a Pt loading of only 0.05 mgPt cm−2. Further stability tests should be carried out for a much longer time to confirm the stability of the catalyst system.