Pulsed‐Laser and Mechanical Reduction of Graphene Oxide Combined with NiCoFeMoW High‐Entropy Alloys for Electrocatalytic Oxygen Evolution Reaction

The development of cost-effective and high-performance electrocatalysts for the oxygen evolution reaction is critical for sustainable energy conversion technologies. In this study, graphene oxide is subjected to two distinct reduction techniques: nanosecond pulsed-laser irradiation and high-energy ball-milling. Structural characterization reveals that laser treatment led to partial reduction, while mechanical treatment achieves a higher degree of reduction. The treatments induce morphological transformations, with laser-irradiated samples exhibiting localized "wrinkling" due to thermal effects, whereas high-energy ball-milling induced "folding" resulted from prolonged mechanical stress. The electrocatalytic performance of reduced graphene oxide is further enhanced by incorporating a NiCoFeMoW high-entropy alloy, prepared by mechanical alloying technique. Electrochemical evaluation demonstrated that the heterostructures exhibited superior electrocatalytic activity, achieving an overpotential of 141.8 mV at 10 mA·cm^- ² for the best sample. These findings underscore the potential of reduced graphene oxide-supported high-entropy alloys as a promising alternative to noble-metal-based electrocatalysts, offering a scalable and environment-friendly approach for advancing water-splitting technologies.