Surface reconstruction enables outstanding performance of Fe2O3/Ni(OH)2 nanosheet arrays for ultrahigh current density oxygen evolution reaction

Development of high-performance, high-stability and low-cost electrocatalysts toward the oxygen evolution reaction (OER) is pivotal to the water electrolysis at industrial current density. Herein, a novel Fe/Ni-based hierarchical structure was constructed with the assistance of 2D MXene, showing vertically aligned Ni(OH)2 nanosheets decorated with distinct Fe2O3 morphologies. The Fe2O3/Ni(OH)2/NF exhibited a remarkable OER activity and required only overpotentials of 291, 319 and 341 mV respectively at 500, 1000 and 1500 mA cm−2 in alkaline solution and drove the current density of 1300 mA cm−2 about 17 h at the potential of 1.64 V vs RHE. The Fe2O3/Ni(OH)2 precursor underwent in situ surface reconstitution into active FeOOH/NiOOH during alkaline OER. The outstanding performance of Fe2O3/Ni(OH)2/NF was attributable to the synergistic impact between FeOOH and NiOOH for regulating the optimal adsorption of OER intermediates. This work provides an ideal perspective to fabricate resource-rich, low-cost and high-activity FeNi-based electrode for alkaline OER at industrial current density.