Abstract

FeCu nanoalloys with controlled compositions were synthesized via thermal decomposition and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) in acidic medium. Four compositions (Fe1Cu0, Fe0.75Cu0.25, Fe0.5Cu0.5, and Fe0.25Cu0.75) were obtained, characterized structurally, magnetically, and morphologically, and incorporated onto glassy carbon electrodes. Electrochemical results demonstrated a positive correlation between Cu content and HER activity. The Fe0.25Cu0.75 sample exhibited the best performance, with an overpotential of –533 mV and exchange current density of 9.0 × 10⁻3 mA·cm⁻2 at 10 mA·cm⁻2 in 0.5 M H2SO4. Long-term stability tests indicated further enhancement in performance, attributed to the reduction of surface oxide phases. These findings highlight the tunability of FeCu nanoalloys and the potential of copper-rich systems as cost-effective alternatives to noble-metal-based HER electrocatalysts in acidic environments.