Pd–Pt alloy/WO₃–rGO nanocomposite as efficient catalyst for the oxygen reduction reaction in PEM fuel cells

Developing cost-effective and highly durable electrocatalysts to overcome the sluggish kinetics of the oxygen reduction reaction (ORR) is critical for the promotion of proton exchange membrane fuel cells (PEMFCs). In this work, a ternary Pd–Pt alloy/WO₃–rGO nanocomposite catalyst was synthesized by a developed two-step chemical reduction method. This strategy enabled the distribution of Pd–Pt alloy nanoparticles very tightly integrated with finely dispersed WOₓ species on conductive rGO support. Structural characterizations confirmed formation of a Pd–Pt alloy phase and strong electronic interactions between the alloy and WOₓ, which resulted in modified surface electronic properties favorable for ORR. Electrochemical characterization revealed that the Pd–Pt–WO₃/rGO catalyst presented the largest electrochemically active surface area (176.29 m² g⁻¹) and superior ORR performance, achieving a mass activity of 83.96 mA mg⁻¹ and a Tafel slope of 70.91 mV dec⁻¹ at 0.9 V vs RHE. The catalyst exhibited superior durability, retaining 94.4% of its initial ECSA after 5000 accelerated cycles, and showed the lowest charge-transfer resistance (0.88 Ω), suggesting its improved conductivity and interfacial charge transfer. The remarkable performance is attributed to the synergistic effects between Pd–Pt alloying, electronic modulation by WOₓ species, and the high conductivity of rGO. These combined features are important for high power density and long stability operability in real PEMFC applications. This study presents a practical pathway for designing high-performance, low-Pt-content catalysts for efficient and durable PEMFCs.