Laser Scribing Synthesis of Carbon Nanotube-Encapsulated Feni₃ Nanoparticles on Carbon Cloth for Water Electrolysis

Introduction/Objective: Efficient, durable, and low-cost bifunctional electrocatalysts for the hydrogen and oxygen evolution reactions (HER/OER) are essential for sustainable water elec-trolysis. This work aimed to develop a green, scalable, ambient-air synthesis of carbon nanotube-confined NiFe alloy nanoparticles on carbon cloth (FeNi₃@CNT/CC) that delivers high HER/OER activity and stability in alkaline media. Methods: A one-step laser-scribing strategy was used under ambient air to fabricate FeNi₃ nanopar-ticles encapsulated by graphitic carbon nanotubes on carbon cloth, yielding a hierarchical porous architecture. Electrochemical performance for HER and OER in alkaline electrolyte was evaluated by polarization, Tafel analysis, and durability testing at constant current. Results: FeNi₃@CNT/CC exhibited low overpotentials of 155 mV (HER) and 297 mV (OER) at 10 mA cm⁻², with favorable Tafel slopes of 149 and 56 mV dec⁻¹, respectively. The catalyst re-tained >95% of its initial activity after 15 hours of continuous operation, outperforming most re-ported transition metal-based analogues in long-term stability. Discussion: The high activity and durability arose from synergistic bimetallic electronic modulation (Fe–Ni), nanoscale encapsulation by conductive graphitic shells that suppressed dissolution and ag-glomeration, and a hierarchical porous framework that accelerated mass transport and electron con-duction. Beyond performance, the ambient laser process obviated the need for inert-gas protection and markedly reduced energy consumption compared to tube-furnace routes. Conclusion: This study has demonstrated a green, cost-effective, and scalable route to robust car-bon-shelled bifunctional electrocatalysts. The ambient-air laser-scribing strategy has offered a ver-satile platform for synthesizing advanced energy materials with high activity and stability for alka-line water splitting.