Oxygen evolution reaction enhancement of copper electrodes in alkaline medium using ultrafast femtosecond laser structuring

In the pursuit of enhancing the oxygen evolution reaction (OER) activity, we employed femtosecond (FS) laser-induced surface nano-structuring to extend the surface area of copper (Cu) electrodes. Compelling surface hierarchical microstructures have been generated on the electrode surface using this approach. By optimizing the laser processing parameters, regular arrays of conical microstructures are fully covered by a thick and porous layer of Cu₂O. Electrochemical measurements reveal that FS laser structuring developed large and structure-tunable surface areas with relative roughness factor between 51 and 61. The enhanced surface area and FS laser-induced Cu₂O layers significantly enhanced the OER activity leading to a reduced overpotential (η₁₀ = 345 mV) that is 70% less than that of pristine Cu at a current density of 10 mA cm⁻². The results demonstrate the effectiveness of femtosecond laser-based surface structuring in enhancing the electrocatalytic OER activity of Cu electrodes in alkaline media.