PtFeNi Trimetallic Alloy Nanoparticles as Electrocatalysts for Oxygen Reductions

Abstract

The large-scale implementation of proton exchange membrane fuel cells remains constrained by the critical challenge of developing cost-effective and durable cathode catalysts capable of withstanding acidic oxygen reduction reaction conditions. While platinum-based binary/ternary alloy systems demonstrate potential for platinum group metal content reduction while enhancing catalytic performance metrics, significant optimization challenges persist. In this study, we report a “prelithiation–deposition” strategy to synthesize carbon-supported PtFeNi ternary alloy nanoparticles with ultralow platinum content (4.35 wt %). Postsynthesis annealing at 800 °C yielded PtFeNi/C-800 catalysts exhibiting superior mass activity (3.41 A mg_Pt^–1 at 0.9 V vs RHE) and specific activity (5.95 mA cm^–2) compared to both binary counterparts (PtFe/C-800, PtNi/C-800) and nonprelithiated controls. Theoretical calculations show that the lithiation process induces new active sites in the carbon material, which promotes the bonding of carbon to the metal. In addition, the synergistic electron precipitation effect and stress effect brought about by alloying optimized the reaction pathways throughout the lifetime; the introduction of iron and nickel altered the electronic structure of platinum, leading to enhanced electronic interactions between the metal nanoparticles and the carbon carriers, all of which combined to provide the PtFeNi/C-800 catalysts with higher catalytic activity and durability.