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.