Femtosecond laser-engineered catalytic electrode nanoarchitectures for efficient bubble detachment during hydrogen evolution reaction of water splitting

Development of high-performance non-precious metal catalysts for hydrogen evolution reaction (HER) in water splitting is essential for advancing low-cost and sustainable hydrogen production technologies. However, practical operation is often hindered by sluggish reaction kinetics and gas bubble accumulations, which block active sites and increase mass-transfer resistance. In this study, trapezoidal femtosecond laser patterned nickel substrates were combined with electrodeposited Ni-Fe-S catalysts to construct hierarchical catalytic electrodes with enhanced bubble-release characteristics and electrocatalytic activity. The optimized Ni-Fe-S/fs-Ni-90 electrode achieved current densities of 10, 20 and 50 mA cm −2 at low overpotentials of 104, 124 and 149 mV, respectively, together with a Tafel slope of 65.8 mV dec −1 and stable operation over 70 h. High-speed imaging revealed that the average bubble diameter decreased from 402 µm on flat Ni to 152 µm on the trapezoidal fs-laser-structured electrode. Phase-field simulations further demonstrated that the laser-generated trapezoidal geometry enhanced bubble detachment by increasing the apparent bubble contact angle and strengthening local flow perturbations near the electrode surface. Rather than introducing a fundamentally new bubble-management concept, this work demonstrates how a specific trapezoidal fs-laser-patterned Ni architecture can be integrated with electrodeposited Ni-Fe-S catalysts to simultaneously improve catalyst accessibility, bubble transport, and HER performance.