Surfactant‐Free Polyol Synthesis of Effective Pd‐Cu Nanomaterials for H ₂ /O ₂ Solid Polymer Electrolyte Fuel Cells

This study presents a facile synthesis of carbon‐supported binarypalladium‐copper (Pd‐Cu/C) nanomaterials designed to achieve competitive catalytic activity while reducing material costs in solid polymer electrolyte (SPE) fuel cells. A surfactant‐free, microwave‐heated polyol process is employed to synthesize Pd/C and Pd‐Cu/C nanomaterials with mean particle size below 4.0 nm. The electrocatalytic activity toward oxygen reduction reaction (ORR) and the corresponding kinetic parameters of Pd‐Cu/C electrodes with varying compositions are systematically interrogated using rotating disk electrode (RDE) measurements. Notably, Tafel analysis reveals a slope of 60 ± 2 mV per decade slope at low current densities indicating that the first electron transfer to molecular oxygen (O ₂ ) is the rate‐determining step. At higher current densities, a slope of 144 ± 8 mV per decade suggests a transition proton‐coupled electron transfer as the dominant mechanism. Furthermore, electrochemical performance of membrane‐electrode‐assemblies (MEAs) reveals a peak power density of ∼ 475 mW cm ⁻² with Pd /C cathode under optimal operating conditions. However, increasing the Cu content in the Pd‐Cu/C catalysts results in a marked decrease in current density, likely due to partial Cu dissolution. These findings highlight the potential of binary Pd‐Cu nanomaterials as promising alternatives to platinum‐based catalysts for Pt‐free SPE fuel cell applications.