Highly Active and Stable Bimetallic Ordered Catalysts for Oxygen Reduction Reaction Improvement in Polymer Exchange Membrane Fuel Cells

Demand for replacing the Pt catalyst in proton exchange membrane fuel cells (PEMFCs) has increased because Pt metal is rare and high cost. The most reasonable way is synthesizing Pt-base alloy using transition metals such as Co, Ni, Fe, and Mo. The Pt-based alloy catalysts exhibit excellent catalytic activity by creating a synergistic effect through the interaction between Pt and the transition metals. Here we present the best PtNi alloy composition and maximize the performance of the oxygen reduction reaction (ORR) activity in fuel cells by annealing the alloy under a hydrogen atmosphere. The Pt7Ni3/C catalyst indicated a higher ORR activity than other compositions due to different structural changes, and the annealing catalysts at 700 °C under an H2 atmosphere improved the electrochemical activity and stability. The heat treatment increased the conductivity by reducing oxygen bonding as well as changing the structure into an ordered face-centered tetragonal (FCT) structure with good activity. The result of these studies provides a new way to develop high-performance and low-cost catalyst materials for fuel cells.