Fluorine-corrosion triggering electrochemical reconstruction of NiFe alloy for boosted oxygen evolution reaction

The development of cost-effective oxygen evolution reaction electrocatalysts is rather meaningful and crucial for water electrolysis in alkaline electrolytes. Herein, we report a simple but feasible approach to prepare NiFe binary alloying coating on Fe plate through laser cladding technology, followed by various halogen-anion (F, Cl, Br) corrosion for optimizing the electrochemical reconstruction in oxygen evolution reaction process. Remarkably, the NiFe-F catalyst demonstrated superior OER activities with delivering typical current densities of 10 and 50 mA/cm² at low overpotentials of 293 and 379 mV, respectively, and possessing a small Tafel slope of 55.2 mV/dec, both are rather lower than those of NiFe-Cl and NiFe-Br counterparts. Additionally, the binary alloy coating catalyst after F corrosion is exceptionally stable in alkaline electrolyte, showing no significant activity degradation for continuous oxygen production over 240 h. Multiple morphology/spectroscopy characterizations and insightful density functional theory (DFT) calculations demonstrate that more high-valence Ni³⁺ and Fe³⁺ centers can be introduced into the binary alloy coating electrode after F corrosion, which benefits the formation of highly-active oxyhydroxyl species (NiOOH, FeOOH), thereby contributing to the improved OER performance.