Pulse Laser-Deposited CrMnFeCoNi High-Entropy Nanoparticles on Carbon Microporous Layer: Entropy-Stabilized Lattice Oxygen Activation for Enhanced Oxygen Evolution

High-entropy alloys (HEAs) are emerging as promising electrocatalytic materials owing to their multi-element synergistic interaction, high configurational entropy, lattice distortion, tuneable electronic structure and excellent corrosion resistance. This study demonstrates the fabrication of an efficient oxygen evolution reaction (OER) electrode by direct pulse laser deposition (PLD) of the CrMnFeCoNi HEA nanoparticles on the carbon-based microporous layer (MPL) in one-step using the pre-prepared CrMnFeCoNi HEA phase, denoted as PLD-CrMnFeCoNi HEA/MPL. This one-step scalable synthesis approach of precisely controlled deposition of HEA on the highly electrically conductive and porous MPL substrate not only simplify the electrode preparation with no binder requirements but also results into the better active site distribution and good catalyst-substrate interaction. The deposition of face-centered cubic crystalline CrMnFeCoNi HEA, and its compositional and morphological features are confirmed by the XRD, SEM and HRTEM analysis. The surface chemistry and oxidation states of each metal component is analyzed by the XPS. Electrochemical OER activity evaluation of PLD-CrMnFeCoNi HEA/MPL in Ar-saturated 1M KOH exhibit an overpotential of 336 mV to achieve a current density of 10 mA cm ^-2 , significantly lower than that of pure Ni/MPL (423 mV) and the state-of-the-art RuO ₂ /MPL (560 mV) under identical testing conditions. The PLD-CrMnFeCoNi HEA/MPL also demonstrate an enhance reactions kinetics with lower Tafel slope value of 44.6 mV dec ^-1 and good electrochemical stability for 5000 CV cycles. The excellent OER activity of PLD-CrMnFeCoNi HEA/MPL is attributed to the multi-element synergism and corrosion resistant characteristics of CrMnFeCoNi HEA and its effective interaction with electrically conductive MPL.